What if

But.....

I know that somebody here built one some time ago in Vietnam era camo - I have a clear memory of it sitting alongside a Wyvern, also in Vietnam colours. I'm thinking 'bout doing one later this year, and ALSO thinking of finishing it in the same scheme, but with black undersurfaces and Air Commando stripes - from the Tamiya A-1 Skyraider.

But as usual, I could be persuaded otherwise.

As depart from my normal 'paints kits differently' mantra, in my minds eye I can see it wearing wingtip tanks, toting LAU-3 pods and festooned with 60's era aerials. So given that I'm seeing it firmly set in the 1960's..... who else would be using the Tigercat (doesn't have to be a CoIn machine) ??. It may be wishful thinking but didn't our own Mr. Helsig  do a couple of profiles in times gone by.

Right enough waffle, over to you lot.... give me some more ideas....

Ian

Quotewho else would be using the Tigercat

How about some of the Bearcat operators - France, Thailand or South Vietnam?  Maybe also Indonesia or the Philippines - keeping in the same general area.

Regards,

Greg

Canada -I know its been done sometime ago.

South America operators.
Brazil
Argentina
Chile
Venezuela
Colombia
Ecuador

Australia
South Vietnam
ROK
ROC
Thailand
Phillipines
Japan

England
FAA
RAF - F7F-2N
West Germany
France
Italy
Greece
Ireland
Norway

I'm thinking RAF too & based on your original idea of Vietnam, an alternative history with Britain involved.  I've thought in the past about an RAF two colour version of SEA camo.  Dark Earth or Olive Green, with Dark Earth, Mid Stone or Light Stone maybe, over LAG?

Howzabout a COIN F7F that borrows the layout of the Lockheed CL760?

Jon

Other than the contribution from Wes' W (aka Tigercat) (http://www.whatifmodelers.com/index.php/topic,4305.0.html) the F7F topic has been minimal.  Jennings' did provide some nice Tigercat WHIF profiles a while back but the the links to the images are no longer supported so the topic that contained them was removed.  Perhaps he can upload them again.  There were several COIN types that he had done in SEA camouflage that were striking.  There was also some discussion within that particular thread about replacing the P&W R-2800 engines on the Tigercat with the Bristol Centarus and some five blade propellers from the Sea Fury.  Jennings' had also obliged with several WHIF Tigercat profiles in Commonwealth markings.  Thanks to those profiles I felt compelled to source a couple of the 1/48th scale Hobby Craft Sea Fury kits to see if I could follow through with a WHIF based on those profiles.

Another possibility would be for a Reno style racer.

Regards,

Greg

Another Brit engine choice would be a late civil-type Hercules 7XX series with rear-swept exhaust, similar in size (52 in diameter versus 52.8 in) and output to the R-2800-22 used in most F7F yet lighter. Add five-blade props and Bristol 170 'Freighter', H-P 'Hermes' or 'Hastings' or similar style cowlings, retaining the grouped ejector exhaust of the F7F, and you're set.

Jon

Quote from: joncarrfarrelly on March 15, 2008, 12:31:48 PM
Another Brit engine choice would be a late civil-type Hercules 7XX series with rear-swept exhaust, similar in size (52 in diameter versus 52.8 in) and output to the R-2800-22 used in most F7F yet lighter. Add five-blade props and Bristol 170 'Freighter', H-P 'Hermes' or 'Hastings' or similar style cowlings, retaining the grouped ejector exhaust of the F7F, and you're set.

Jon

When I did my Mk.31 Freighter I used the Magna Models conversion.  Among the many bits in the conversion you get are a pair of cowlings and in the past I have been able to get selective parts from Magna, albeit it was through Aircraft in Miniature at the time as they were the distributor for Magna until they practically closed down.

Maybe an email to Magna might produce just the cowlings.

Have pulled these off the site previously:

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh4.google.com%2Fphil13%2FR9xlr_coiOI%2FAAAAAAAACm0%2FLDiGeFtLaho%2Fpost-39-1178173913.jpg%3Fimgmax%3D720&hash=32d160d2d7cbbf5b8f954dfb9a721dcc6702f8e0)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh5.google.com%2Fphil13%2FR9xj0PcoiJI%2FAAAAAAAAClw%2FQFvXlzq2Xm0%2FSEA_Tigercat.jpg%3Fimgmax%3D720&hash=357bc747d254e20cf308fbff1943bf0ebb6d06cd)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh4.google.com%2Fphil13%2FR9xj6_coiKI%2FAAAAAAAACl4%2F5EWf2yV4Hzk%2FRN_Tigercat_FB1_Korea.jpg%3Fimgmax%3D720&hash=6a72348b97f60650afc4b889779f6e8f3ffb9e1d)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh5.google.com%2Fphil13%2FR9xlrPcoiLI%2FAAAAAAAACmY%2FTASa8htoi1Q%2FCentaurusTigercat.jpg%3Fimgmax%3D720&hash=2751066dadcf3388bf9f00b30c2942bcdce96e8f)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh5.google.com%2Fphil13%2FR9xlsPcoiPI%2FAAAAAAAACm8%2F6f6of7mHW2Q%2FRCN_Tigercat.jpg%3Fimgmax%3D720&hash=dd95411f16a169f1d3d73c6d8de875b01de9269f)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh6.google.com%2Fphil13%2FR9xlsfcoiQI%2FAAAAAAAACnE%2FNFwJ8x67ceE%2FRAN_Tigercat.jpg%3Fimgmax%3D720&hash=e40603550724eb2e395f4792f8d76bb92be8e20d)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh3.google.com%2Fphil13%2FR9xlrvcoiMI%2FAAAAAAAACmg%2Fsao0voHjL8M%2FBanff_Tigercat.jpg%3Fimgmax%3D720&hash=a7254350af49476caf861ac0ce13053c49a0e6e2)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh3.google.com%2Fphil13%2FR9xlrvcoiNI%2FAAAAAAAACms%2FB34Vd5Qk8bo%2FAtlanticF7F-3.jpg%3Fimgmax%3D720&hash=e9ccd8bd0cf5773ab80b5f1701f70256f44500e6)

Wow, looks like that might have actually worked.

Here are some civvy versions I also grabbed earlier:

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh3.google.com%2Fphil13%2FR9xe9vcoiBI%2FAAAAAAAACkw%2F1IENXk3BuQw%2FFireCat22.jpg.jpg%3Fimgmax%3D720&hash=18a0f9aa83b314ef90e0b67d537092c03ff64065)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh4.google.com%2Fphil13%2FR9xe9_coiCI%2FAAAAAAAACk4%2FEeAuPhKCUHM%2FTigercat28-CD.F.jpg.jpg%3Fimgmax%3D720&hash=8c27fe24290cbcccbdfcaae97047931f9da99133)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh5.google.com%2Fphil13%2FR9xe-PcoiDI%2FAAAAAAAAClA%2F984CWqjO9Zs%2FLeadCat.jpg.jpg%3Fimgmax%3D720&hash=db26400cdf38ab067af37f4fe173d6badac47277)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh6.google.com%2Fphil13%2FR9xe-fcoiEI%2FAAAAAAAAClI%2FXZZl22WaNY0%2FFireCat1.jpg.jpg%3Fimgmax%3D720&hash=fdceef175c1cdd2681cb70f771b9cca1ff5b90fa)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh6.google.com%2Fphil13%2FR9xe-fcoiFI%2FAAAAAAAAClQ%2Fj-Zv8BtSCRw%2FProvinceofNewFoundlandLabradorFirec.jpg.jpg%3Fimgmax%3D720&hash=44b723d413f972b853dded1f1d2ae3fc792b4e73)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh3.google.com%2Fphil13%2FR9xe-vcoiGI%2FAAAAAAAAClY%2FenRP69AdZr0%2FLeadCatI_edited.jpg.jpg%3Fimgmax%3D720&hash=1fcbd2a14229f28715b93d2f13b9916656579997)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh4.google.com%2Fphil13%2FR9xe-_coiHI%2FAAAAAAAAClg%2F8DngjAYOxCA%2FFireCat139.jpg%3Fimgmax%3D720&hash=efc8023707e822313e02acf47dc12643bac76f83)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Flh5.google.com%2Fphil13%2FR9xe_PcoiII%2FAAAAAAAAClo%2Faxhpwmse37c%2FFireCat133.jpg%3Fimgmax%3D720&hash=61b7d484526e38ebc60e67bb289bdd9ad8cd6074)

The tank has been done as a conversion kit in both 72nd and 48th scale.

That's great, Phil, I knew I wasn't going crazy about those profiles. I'm still inclined to build a Vietnam CoIn machine. I mentioned in the lead-in post that I was thinking 'bout using the Tamiya A-1H decals.... well the aircraft in Jennings 'TC' coded profile is wearing those markings almost exactly..... great minds and all that  :rolleyes:

Still set-on the wingtip tanks too, but also now thinking of substituting the props for those in the Tamiya F-51 kit. Four bladed with a spinner would change the appearence quite noticeably. This means I would have to build the F-51's as standard P-51's with cuffed Hamilton props but that's not any sort of hardship is it ?

Thanks for all the help and inspiration so far, chaps..... Keep 'em coming.

Ian

I was thinking just lately that a COIN/FAC F7f Tigercat would be easy to do using the old Monogram kit or any of the newer releases. As a FAC plane it would already have advantages over the O-1/O-2s with the use of the 4X.50 cals and the 4X 20mm guns. The hardpoints on the wings would need little modification if any to use the rocket pods the O-2s used  and they could be supported by either F-8F Bearcats or A-1 Skyraiders.

These pics dont add much to the debate, but what the heck.  I took these last summer (a year ago this week in fact) at the airshow in Oshkosh, Wisconsin.  One of the themes last year was Unlimited class Air Racers, and they had a couple of Mustangs (which were unfortunately involved in a fatal accident the day after we left), a Corsair, a Sea Fury, and this Tigercat, the only one on the race circuit.  Now, there are few sounds I like better than a RR Merlin at full boost, but the noise this thing made going past at a pretty leisurely pace of about 300kts made the hair on the back of my neck stand up.

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi33.photobucket.com%2Falbums%2Fd87%2FAeroplaneDriver%2F353.jpg&hash=ad47182b699d171a5c6cf3d1c41e47b89fe7290c)

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi33.photobucket.com%2Falbums%2Fd87%2FAeroplaneDriver%2F354.jpg&hash=7f045c86ec53fece33db7b926d8cc3971152cc76)

Nice pic Nick! :ph34r:

Don't know how far you're on with this Ian, but a Football War machine in either El Salvador or Honduras colours would look good.  It fits the sixties time frame, & the aerial fit would have been of the era.  There's some great jungle camo schemes that both sides wore (& all individual so you could have a bit of fun with your own scheme), have a look on the ACIG page:

http://www.acig.org/artman/publish/printer_156.shtml (http://www.acig.org/artman/publish/printer_156.shtml)

Another idea: Super TigerCat

I have an old Monogram 1/72 TigerCat. I could increase wingspan and fuselage length somehow and equip it with Wasp Majors.  :wub: :thumbsup:

I would have to presume that if the USAAF/USAF had adopted the Tigercat as the P-65 it would have been built without the wing fold mechanism.  With that in mind I wonder how much more ordnance could have been carried under the wings and how many additional stores pylons could have been mounted to this stronger wing. 

      There was a model of one, supposedly based on a real plan, at some model contest a few years ago. Something 'Doll' was its name, IIRC & the racer was supposed to have been powered by R-3350s.

Quote from: GTX on March 15, 2008, 11:29:07 AM
Another possibility would be for a Reno style racer.

Regards,

Greg

     I may have posted pics of mine in SEA camo, but it wouldn't have been with a Wyvern. I can get another pic, tho.

Quote from: Ian the Hunter-Gatherer on March 14, 2008, 10:45:18 AM
But.....

I know that somebody here built one some time ago in Vietnam era camo - I have a clear memory of it sitting alongside a Wyvern, also in Vietnam colours. I'm thinking 'bout doing one later this year, and ALSO thinking of finishing it in the same scheme, but with black undersurfaces and Air Commando stripes - from the Tamiya A-1 Skyraider.

But as usual, I could be persuaded otherwise.

As depart from my normal 'paints kits differently' mantra, in my minds eye I can see it wearing wingtip tanks, toting LAU-3 pods and festooned with 60's era aerials. So given that I'm seeing it firmly set in the 1960's..... who else would be using the Tigercat (doesn't have to be a CoIn machine) ??. It may be wishful thinking but didn't our own Mr. Helsig  do a couple of profiles in times gone by.

Right enough waffle, over to you lot.... give me some more ideas....

Ian

Quote from: Jeffry Fontaine on December 24, 2008, 04:23:07 AM
I would have to presume that if the USAAF/USAF had adopted the Tigercat as the P-65 it would have been built without the wing fold mechanism.  With that in mind I wonder how much more ordnance could have been carried under the wings and how many additional stores pylons could have been mounted to this stronger wing. 

The Army XP-65 wasn't actually a variation of the USN F7F, both were iterations of Design 51.

The story starts with the Grumman Design 46 of October 1939, a large twin 1,600hp R-2600 powered aircraft (two-stage mechanical superchargers or turbo-superchargers) for the Army. A derivative was offered for export in February 1940 as the Design 49.
The preliminary design work for these two projects worked to Grumman's advantage when they decided to submit a proposal to a 21 December, 1940 RFP for specification SD-112-18. Seeking to satisfy both Army and Navy requirements, Grumman incorporated most features of Designs 46 and 49 into the Design 51 proposal, which was submitted to BuAer 24 March, 1941, and emerged as the winner of the Navy competition on 14 May. By then the Army and Navy and had agreed to seek the development of twin-engined fighters differing only in details, the Army opted for turbo-superchargers, the Navy for mechanical superchargers. The Army version was to be pressurized and armed with two 37mm cannon and four .50 MG, whereas the Navy version was to be unpressurized and armed with four 20mm cannon in place of the two 37mm weapons.
The Army ordered two XP-65 prototypes on 16 June, 1941 and two weeks later the Navy ordered two F7F-1 prototypes. Subsequently, however, both services concluded that a single design would not meet their specific requirements and on 16 January, 1942 the Army dropped out of the program to allow Grumman to optimize the design to meet the Navy requirements. Among the many design changes that were incorporated into the mockup (which passed inspection September 1942) was a change from mid-mounted to shoulder-mounted wings. Detail design and construction of the prototype proceeded slowly, the engines were changed from R-2600 to R-2800 and the official first flight was made on 3 November, 1943 (there had been a 15 second hop the previous day following high-speed taxi runs).
- paraphrased from Grumman Aircraft since 1929, Rene J Francillon, 1989 Putnam/NIP

So basically, in engineering terms, the XP-65 died long before the configuration of the F7F was finalized.

As to Tigercat 'derivatives:
Design 66, Torpedo Bomber (3-view attached)
Design 67, mixed-power with an I-20 turbojet mounted in the aft end of each nacelle, estimated 505mph at 20,000 ft.
Design 80, high-speed executive transport using the wings and powerplant installation of the F7F.

Jon

What if Chance Vought produced an aquivalent to Tigercat, but based on Corsair I ?

EDIT: F4U CORSAIR

vvvvvvvv

       Technically speaking, the "Corsair I" is a biplane scout from the '30s, the OSU, IIRC, so I'm guessing you mean the F4U, which everyone knows as the Corsair. I read in some F4U book a few years ago that Vought's original design for the F6U was a design similar to the F7F, so I can imagine something like an F7F with Vought characteristics, not an inverted gull wing tho, but similar in vein to Vought's proposal for the ASW a/c that was won by the Grumman S2F, where the Vought a/c looks kinda like an S2F.

Quote from: ysi_maniac on September 30, 2009, 05:50:55 AM
What if Chance Vought produced an aquivalent to Tigercat, but based on Corsair I ?

The photos of the Tigercats with the Wyvern in SEA markings was mine; I am sure it is here somewhere in the What If archives.  I am currently switching to a new computer system, and will be several days before I can upload more photos.


I have also thought that the Tigercat would have made a superb aircraft for many roles in the SEA conflict.



Wes W.

Don't forget Israel......

Here is the thread with the Wyvern in SEA cammo.  If the aircraft had a reliable turbo prop engine, it seems as if it could have been a supplement/replacement for the A-1.

http://www.whatifmodelers.com/index.php/topic,5921.0/highlight,wyvern.html



Wes W.

When I can eventually find a 1/72nd scale Tigercat, I want to convert it into a turbo prop modern day COIN aircraft.
Keep the nose guns, put wing tip tanks on, fit a FLIR turret under the nose or rear fuselage. Weaponry can consist of the usual free fall bombs gun/rocket pods, but it could also carry Hellfire and maverick missiles. A maritime patrol aircraft would also be a good option, with the turbo prop engines, and armed with Sea Skua's, Penguins and a pair of heavy rocket pods and a FLIR turret. The nose could be modded to house a radar, and the guns could be housed in a belly pack.
But I have yet to find one :huh:...............bugger :angry:
Chris.

Chris-----PM inbound!

      There are several on eBay..........

Quote from: chrisonord on October 02, 2009, 08:11:06 AM
When I can eventually find a 1/72nd scale Tigercat, I want to convert it into a turbo prop modern day COIN aircraft.
Keep the nose guns, put wing tip tanks on, fit a FLIR turret under the nose or rear fuselage. Weaponry can consist of the usual free fall bombs gun/rocket pods, but it could also carry Hellfire and maverick missiles. A maritime patrol aircraft would also be a good option, with the turbo prop engines, and armed with Sea Skua's, Penguins and a pair of heavy rocket pods and a FLIR turret. The nose could be modded to house a radar, and the guns could be housed in a belly pack.
But I have yet to find one :huh:...............bugger :angry:
Chris.

For a different Tigercat, how about one with Centaurus engines and five-bladed props?  In, say, SEAC markings as operated either from land or from a RN or RAN fleet carrier?

      Here's my "F-65C".

Quote from: Ian the Hunter-Gatherer on March 14, 2008, 10:45:18 AM
But.....

I know that somebody here built one some time ago in Vietnam era camo - I have a clear memory of it sitting alongside a Wyvern, also in Vietnam colours. I'm thinking 'bout doing one later this year, and ALSO thinking of finishing it in the same scheme, but with black undersurfaces and Air Commando stripes - from the Tamiya A-1 Skyraider.

But as usual, I could be persuaded otherwise.

As depart from my normal 'paints kits differently' mantra, in my minds eye I can see it wearing wingtip tanks, toting LAU-3 pods and festooned with 60's era aerials. So given that I'm seeing it firmly set in the 1960's..... who else would be using the Tigercat (doesn't have to be a CoIn machine) ??. It may be wishful thinking but didn't our own Mr. Helsig  do a couple of profiles in times gone by.

Right enough waffle, over to you lot.... give me some more ideas....

Ian

Quote from: chrisonord on October 02, 2009, 08:11:06 AM
When I can eventually find a 1/72nd scale Tigercat, I want to convert it into a turbo prop modern day COIN aircraft.
Keep the nose guns, put wing tip tanks on, fit a FLIR turret under the nose or rear fuselage. Weaponry can consist of the usual free fall bombs gun/rocket pods, but it could also carry Hellfire and maverick missiles. A maritime patrol aircraft would also be a good option, with the turbo prop engines, and armed with Sea Skua's, Penguins and a pair of heavy rocket pods and a FLIR turret. The nose could be modded to house a radar, and the guns could be housed in a belly pack.
But I have yet to find one :huh:...............bugger :angry:
Chris.

For years I have been ordering OOP kits from Dean's Hobby Stop in Michigan.  His prices are great, and there always seems to be Monogram Tigercats in stock.


Wes W.

Quote from: chrisonord on October 02, 2009, 08:11:06 AM
When I can eventually find a 1/72nd scale Tigercat, I want to convert it into a turbo prop modern day COIN aircraft.
Keep the nose guns, put wing tip tanks on, fit a FLIR turret under the nose or rear fuselage. Weaponry can consist of the usual free fall bombs gun/rocket pods, but it could also carry Hellfire and maverick missiles. A maritime patrol aircraft would also be a good option, with the turbo prop engines, and armed with Sea Skua's, Penguins and a pair of heavy rocket pods and a FLIR turret. The nose could be modded to house a radar, and the guns could be housed in a belly pack.
But I have yet to find one :huh:...............bugger :angry:
Chris.

Chris --- check out Kingkit, they have a couple for just under 20 quid each  
http://www.kingkit.co.uk/kingkit/

These guys seem pretty good - either that or its my imagination because they have the 1/72 Concorde and B-1B for just under 30 quid!

Then again, to a no-budget guy like me from the States that still seems like a lot :P

Hey, chrisonord, I looked in my stash, and I have TWO 1/72 Tigercat kits---an UN-built Monogram one, and the Aoshima (actually quite good) one in the same box, along with a conversion kit for the extra window for the radar operator behind the pilot. The Aoshima one has the large propeller spinners. The partially-built kit from Bill Gruner I thought I had is.....gone? Dunno.

I would love to "trade" this/these for an MPM/Special Hobby Brewster Buccaneer or equivalent $$.

PM me, please!

Quote from: famvburg on October 02, 2009, 03:59:38 PM

      Here's my "F-65C".

Love it! But then again, I love the F7F so much that even a conversion as an ice-cream parlor or garbage collector would look nice to me!  ;D

Quote from: kitnut617 on October 03, 2009, 09:44:09 AM

Quote from: chrisonord on October 02, 2009, 08:11:06 AM
When I can eventually find a 1/72nd scale Tigercat, I want to convert it into a turbo prop modern day COIN aircraft.
Keep the nose guns, put wing tip tanks on, fit a FLIR turret under the nose or rear fuselage. Weaponry can consist of the usual free fall bombs gun/rocket pods, but it could also carry Hellfire and maverick missiles. A maritime patrol aircraft would also be a good option, with the turbo prop engines, and armed with Sea Skua's, Penguins and a pair of heavy rocket pods and a FLIR turret. The nose could be modded to house a radar, and the guns could be housed in a belly pack.
But I have yet to find one :huh:...............bugger :angry:
Chris.

Chris --- check out Kingkit, they have a couple for just under 20 quid each  
http://www.kingkit.co.uk/kingkit/
Cheers for the heads upon those Robert, but 20 quid????? half that price is more like what I want to pay for one.
Thanks anyway,
Chris.

Simplest idea, how about inline engines, maybe Allison V-1710's or Packard Merlins?  I've always thought that those fat radials with the slim fuselage make a pretty figure look slightly odd.  Going a step further, you could use the arrangement used on the DH Hornet for an even slimmer look.

Like this?

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fwww.acme-engineering.nl%2Fmodel%2FTigercat-side2.jpg&hash=c4f3ab645eef803467fccb716f1ff3b080c20507)

http://www.whatifmodelers.com/index.php/topic,17847.0.html (http://www.whatifmodelers.com/index.php/topic,17847.0.html)

Not quite what I had in mind, the big Napier Nomad & annular intakes give it a similar look to a radial.  Something a bit smaller & slimmer was the kind of look I was thinking of.  Cool though! :thumbsup:

Are you thinking of Zeke's that was up for a Whiffie last year?

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv634%2Fsae05%2FMooncat_2_final.jpg&hash=04f0c10ec6b887f0239b604fff6846f1e8804403)

http://www.whatifmodelers.com/index.php/topic,23011.45.html

Quote from: philp on February 07, 2011, 01:32:38 PM
Are you thinking of Zeke's that was up for a Whiffie last year?

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv634%2Fsae05%2FMooncat_2_final.jpg&hash=04f0c10ec6b887f0239b604fff6846f1e8804403)

http://www.whatifmodelers.com/index.php/topic,23011.45.html

Gee!!!  :o :o :o

I hadn't seen that one. Surely deserved a Whiffie! Brilliant in every way.

Quote from: Mossie on February 07, 2011, 07:34:02 AM
Simplest idea, how about inline engines, maybe Allison V-1710's or Packard Merlins?  I've always thought that those fat radials with the slim fuselage make a pretty figure look slightly odd.  Going a step further, you could use the arrangement used on the DH Hornet for an even slimmer look.

I think Hornet/Mosquito-style Merlins (or even Grifffons) with leading-edge radiators could look very good indeed. :thumbsup:

Anyone know what happened to Zeke? He disappeared quite suddenly a while back...

That's what I was after! :thumbsup: :thumbsup: :thumbsup:

Thrust line, I'm never quite sure how much importance this should be given.  I think it's less important with multi-engine types, there tend to be more that have swapped radials & inlines than single eninge types?  Visibility is just 'different' to the radial engined machine I guess, pros & cons & all that.

PS, loving that COIN Tigercat!

Here's another thought, cut down the spine a bit, add a long bubble canopy to it like that of the F-15 Reporter for extra slinky-ness. :party:

     What little I'm aware of, thrust lines are quite important. Some things I've read indicate it can have an effect similar to the a/c center of gravity, so it's pretty crucial.

Quote from: Mossie on February 08, 2011, 03:05:55 AM
That's what I was after! :thumbsup: :thumbsup: :thumbsup:

Thrust line, I'm never quite sure how much importance this should be given.  I think it's less important with multi-engine types, there tend to be more that have swapped radials & inlines than single eninge types?  Visibility is just 'different' to the radial engined machine I guess, pros & cons & all that.

PS, loving that COIN Tigercat!

Quote from: Mossie on February 08, 2011, 03:40:39 AM
Here's another thought, cut down the spine a bit, add a long bubble canopy ...

Maybe graft on a Bearcat upper fuselage and cockpit/canopy?

Quote from: apophenia on February 08, 2011, 02:18:31 PM

Quote from: Mossie on February 08, 2011, 03:40:39 AM
Here's another thought, cut down the spine a bit, add a long bubble canopy ...

Maybe graft on a Bearcat upper fuselage and cockpit/canopy?

Raising the cockpit would obviously increase vision.  Unfortunately, it also increases drag.  With the decision to not change the engine nacelles, you've already added considerable drag to an inline engined machine.   Slim those down and then raise the cockpit and you might compensate for the increased drag from the cockpit's new position.  An F8's cockpit would look good, I think but aren't we essentially simply redesigning the Hornet here?  ;)

Quote from: rickshaw on February 08, 2011, 03:53:15 PM
... but aren't we essentially simply redesigning the Hornet here?  ;)

Yup  ;D  I wasn't suggesting raising the cockpit though. Just substituting a bubble canopy.

Quote from: apophenia on February 08, 2011, 08:57:30 PM

Quote from: rickshaw on February 08, 2011, 03:53:15 PM
... but aren't we essentially simply redesigning the Hornet here?  ;)

Yup  ;D  I wasn't suggesting raising the cockpit though. Just substituting a bubble canopy.

An American Hornet?   Perhaps it should be coloured green instead of blue?  ;)

Show us!  :)

Not me.  My idea was simply to slim the Tigercat down & give it mods to take it in line with late/post war developments.  Also just to further pretty up what is already a pretty aircraft.

Quote from: Mossie on February 09, 2011, 06:23:38 AM
Not me.  My idea was simply to slim the Tigercat down & give it mods to take it in line with late/post war developments.  Also just to further pretty up what is already a pretty aircraft.

Never found the Tigercat all that pretty myself.  Personally I prefer the Hornet for the same role.  Now there's a pretty plane!   :wub:

Side-by-side-by-side comparison; de Havilland Hornet. Westland Whirlwind & Grumman F7F Tigercat.

I find both British birds prettier than the American but a Merlin/Griffon powered Tigercat might look better (if the fuselage is made a little less anorexic).

Bah! The Whirlwind looks like a pencil, and the Hornet's tail and nose are ugly! Saw the Tigercat fly and it's such a beautiful machine. Feline in every way. True, it is a little slim, but that would be perfect for a COIN aircraft!

"Eye of the beholder" & all that. :thumbsup:

Yep. Meanwhile, may I suggest... the Westland Wildcat I.  ;D

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Faviadesign.online.fr%2Fimages%2Fwestland-wildcat.jpg&hash=f2b1cf772a555a154c7332b5eb3b0aacdc1f2468)

I would suggest a Welkin tail SG2006 ---  ;)

Quote from: Stargazer2006 on February 09, 2011, 07:17:51 AM
Bah! The Whirlwind looks like a pencil, and the Hornet's tail and nose are ugly! Saw the Tigercat fly and it's such a beautiful machine. Feline in every way. True, it is a little slim, but that would be perfect for a COIN aircraft!

Don't let the Wooksta read this - he'd probably set you on fire! :wacko: I wish I had the chance to see either of the other two fly, but that will never happen.

I much prefer both British machines - the Tigercat is a weird mix, the very thin, boxy fuselage and those big fat round nacelles don't quite gel IMO. Your Wildcat is very nice indeed, though I think it would be much improved with a bubble canopy and a slightly shorter/rounder nose. :thumbsup:

Quote from: kitnut617 on February 09, 2011, 09:35:18 AM
I would suggest a Welkin tail SG2006 ---  ;)

I almost DID use a Welkin tail... before deciding I was going to do something ELSE with the Welkin... Great minds!!

Also the challenge here was to find an aircraft that would combine all three designs suggested above, so I stuck to these...

May I suggest a T-tail Mosssie with a Tigercat nose ?  ;D
(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi703.photobucket.com%2Falbums%2Fww37%2Fjmsfbip%2FTT-Moshark-2.png&hash=689476282dbfc9d6c5f17ec3e00ea4ef979c4fe6)

Um, no? :blink:

That one warps my eyeballs! :o

Was thinking of doing a cut and shut job on a F7F to create a slim, V-1710 engined F6F type fighter for the USAAF. I have a donor ready but have to admit to being a little hesitant. How rare are Monogram F7Fs these days?

Not easy but then again, not difficult to find either.  Revell reboxed them recently, at least within the last ten years.

Ah, thanks for that. The project has stalled but is very much still on my to do list.

I like your idea of doing an F7F Tigercat with wing tip tanks and SEA camo.
Here is my F7F-3 Junglecat I am almost finished with. Still needs antennas and decals. Its a 1/48 scale AMT/ERTL.
(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Ffarm6.static.flickr.com%2F5095%2F5536109291_5a37fdbff9_b.jpg&hash=907d31b0c4ec393dc929e2f1df4983347dedaf0c) (http://www.flickr.com/photos/15380629@N08/5536109291/)

Nice Tigercat  :thumbsup:

Always liked the aircraft. I have one in the stash which will eventually be BPF.

Mmm, just had a thought.  Slim-line nacelles, with mmmm, Griffins?  Interestingly different look, methinks.

Or Merlin 130/131s, a la Hornet. :thumbsup:

I've got one somewhere that'll be a FAA one - cut down fuselage, bubble hood, Centaurus engines (the US were looking at licence building it) and five blade props.

However, it's been sitting there for four years so I doubt it'll get done anytime soon.  At least not for another year...

Tigercat is quite sleek that's why I think she deserves sleeker engines like RR Griffon. Wings have been a little enlarged too.

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi1080.photobucket.com%2Falbums%2Fj340%2Fysi_maniac%2FDrawing%2Ftigercat_griffon.jpg&hash=98d6fc0351eb720d337381b96feb1a78956294be)

Nice Griffon Tigercat  :thumbsup:

The F7F from what I remember was to be built in parallel with a USAAF concept called the P-65 which was to differ in the following

• Pressurized Cockpit
• Turbocharger

Would the turbocharger alter the shape of the nacelle at all or in any significant way?

http://www.whatifmodelers.com/index.php/topic,19302.msg324263.html#msg324263

JCF

That's actually fascinating: I always thought the F7F and P-65's were derivatives of each other. 

I didn't know the design continued to be modified several times over before it would proceed to the F7F

Thanks for the information

I was doing some looking at these pages
http://www.wwiiaircraftperformance.org/f7f/F7F-1_80262.pdf
http://www.wwiiaircraftperformance.org/f7f/F7F-1_Airplane_Characteristics_Performance.pdf

Honestly some of this data makes little to no sense

• In the first document it seems to list the critical altitude as 23,400' or 23,500' at military power and 24,000 at normal power with both engines running
  
• In the second document I'm kind of puzzled that they would list the performance figures based on a cruise of 15,000 feet: Generally the best performance favors a cruising altitude at or slightly above the critical altitude
  
• The climb performance data specified in the second document seems rather difficult to make sense of: While either set of graphed data indicates an unusually high climb-speed, one seems to show climb figures that are more jet-like (faster you go, faster you climb); Are one of these figures a zoom-climb?
  

I wish they'd made a Tigercat with a bubble canopy. Like the one they put on the Bearcat, or smaller. If a second crew member is needed, he could have a small bubble like on Beaufighter or DH Sea Hornet.

Hi, KJ,
The aircraft critical altitude during high speed flight is not same as engine's critical altitude - in most cases it is significantly higher, depending on the true air speed, how good is the ram air intake projected & executed, and whether there is something that might obstruct o rinterfere with the airflow prior entering the supercharger. With that said, the F7F-1 having the critical altitude at 23400 ft when on military power is suspiciously high, I agree.
The altitude where the cruise is performed depends on current doctrine and level of technology, not where this or that engine has the critical altitude.
None of RoC figures in the doc are for zoom climb.

tomo pauk

QuoteWith that said, the F7F-1 having the critical altitude at 23400 ft when on military power is suspiciously high, I agree.

How would one figure out the range at the critical altitude?

QuoteThe altitude where the cruise is performed depends on current doctrine and level of technology, not where this or that engine has the critical altitude.

So it's doctrine based more than engine based?

QuoteNone of RoC figures in the doc are for zoom climb.

Then why does the graph look so weird?

Quote from: KJ_Lesnick on November 23, 2015, 08:19:52 PM
How would one figure out the range at the critical altitude?

By applying the elementary school maths upon the flight manual.

QuoteSo it's doctrine based more than engine based?

It also takes into account whether one can realistically fly at this or that altitude, and whether the flight is above water or enemy held territory.

QuoteThen why does the graph look so weird?

It does not.

Tomo Pauk

QuoteBy applying the elementary school maths upon the flight manual.

I don't know the mathematics formula required actually

QuoteIt also takes into account whether one can realistically fly at this or that altitude, and whether the flight is above water or enemy held territory.

Wouldn't it be easier to fly high -- enemy fighters would often have to struggle to get you

QuoteIt does not.

It looks like there are two different sets of figures that go in different directions.  If the one on the right is climb-performance with speed -- it behaves more like a jet.

Quote from: KJ_Lesnick on November 25, 2015, 08:59:44 PM

Quote

Quote from: KJ_Lesnick on November 23, 2015, 08:19:52 PM
How would one figure out the range at the critical altitude?

By applying the elementary school maths upon the flight manual.

I don't know the mathematics formula required actually

miles per gallon x gallon = miles

Tomo talks of the charts in flight manuals that show fuel burn at different altitudes and engine settings (cruise speeds).

Quote from: KJ_Lesnick on November 25, 2015, 08:59:44 PM
I don't know the mathematics formula required actually

Covered by wuzak.

Quote
Wouldn't it be easier to fly high -- enemy fighters would often have to struggle to get you

Agreed, plus it makes enemy AAA non-factor.
However, the piston-engined aircraft, esp. the ones with non-turbo engines, will give better mileage flying low and slow.

QuoteIt looks like there are two different sets of figures that go in different directions.  If the one on the right is climb-performance with speed -- it behaves more like a jet.

One set of graphs is for the air speed, another set of graphs is for rate of climb.

Great stuff about the reworked F7Fs.
The (obviously) US-produced bird for the USAF - can use 2-stage Packard Merlins (advantage vs. R-2800 is much more power above 20000 ft, less drag, greater mileage), or two-stage V-1710 (less drag & better mileage vs. R-2800, not using and intercooler means easier installation vs. Packard Merlin). Having only one crew member being both advantage and disadvantage vs. P-82.
Another option might be the turbo in the back of nacelle, coupled with a V-12 in front, like seen at XP-67 'Moonbat'. Or maybe a V-1710 in the turbo compound layout, for 3000 HP per engine like in the V-1710-127? Of course, the turbo-compound R-2800 would've also turn the F7F into a rocket.

I've merged these 2 topics

Chris

NARSES2

QuoteI've merged these 2 topics

Thanks: The thread was sort of beginning to morph to a point where it was first about boosting a design like the XA-41 into something longer ranged and faster; and from there to the physics behind piston aircraft (which was clearly in furtherance of the original subject at first) which eventually deviated into it's own subject, and then from there into an idea around the F7F.

tomo pauk & wuzak

For the purpose of moving everything to the right spot, I've ended up chronicling things from the previous thread as a sort of repository of where we left off.  I've color coded the poster listing in red, green, and blue: Red will be for me, green will be for wuzak, and blue will be for tomo pauk


BEGIN CHRONICLE


Poster: KJ_Lesnick
Date: 11/20/2015
Time: 00:53:28 AM

Tomo Pauk

QuoteBoth F7F an F8F used single-stage supercharged engines, without intercoolers.

I beg to differ,
http://www.wwiiaircraftperformance.org/f7f/F7F-1_80262.pdf
Performance charts clearly list low and high blower

QuoteAll of those four USN fighters mentioned used water-alcohol injection, the Hellcat and Corsair starting from early 1944 on.

That's correct, and that allowed more horsepower to be produced


Poster: wuzak
Date: 11/20/2015
Time: 01:20:07

QuoteTomo Pauk

QuoteBoth F7F an F8F used single-stage supercharged engines, without intercoolers.

I beg to differ,
http://www.wwiiaircraftperformance.org/f7f/F7F-1_80262.pdf
Performance charts clearly list low and high blower

Means it is two speed, not two stage.

It allowed more boost to be used and thus more power. But also that would be at a lower altitude.


Poster: KJ_Lesnick
Date: 11/22/2015
Time: 22:44:47

Wuzak & Tomo Pauk
I'm confused about a couple of things
Regarding the F4F

• I've received all sorts of conflicting information on the F4F Wildcat
  
• One website says the F4F was thought to be the first aircraft to use a twin-speed, twin-stage supercharger
  
• "Wings of the Navy" by Captain Eric M. Brown lists the F4F to have a twin-speed, twin-stage supercharger with inter-cooling
  
• Other sources seem to state a twin-stage, single-speed supercharger
  
• The http://wwiiaircraftperformance.org page seems to show performance curves for the F4F that indicate a single-speed supercharger
  

Regarding the F7F

• I'm curious why the F7F would use a single-stage supercharger when the F4F, F6F, and F4U used twin-staged
  
• I'm also curious why they'd do away with inter-cooling
  
• I figure either would jack up the critical altitude well above the amount specified
  

.

Poster: tomo pauk
Date: 11/22/2015
Time: 23:08:30

The engines, whether Cyclones or Twin wasps on the F4F, were always 2-speed supercharged. Most of the people don't separately state that any 2-stage engine have had an intercooler (reasoning it is understood as such), and the 2-stage, 2-speed version of the Twin wasp featured a pair of intercoolers indeed. The F4Fs with single stage Twin wasps were with suffix 'a' - ie. F4F-3a. Sometimes, the gearing on the 2-stage P&W engines is described as 3-speed, since the 1st stage could be de-clutched - only in low altitudes, where it is not needed, hence leaving more engine power to drive the prop.
No ww2 aircraft engine that matter used only 1-speed gearing when was outfitted with a gear-driven 2-stage supercharger; the US engines did use 1-speed for engine-stage impellers, though (and multiple gears for 1st stage) - they did not featured both impellers on same drive shaft as it was common by RR 2-stage engines.

The sigle stage radial engine is very difficult to intercool/aftercool, there is no single intake manifold that leads from compressor to the cylinders. The US 2-stage radials used intercooler to cool down the compressed air that went from 1-st stage to 2-nd stage of the compressor system. RR 2-stage engines cooled down the air/fuel mixture that went through both stages, one after another.
Why no 2-stage engines on the F7F (and F8F)? Probably a matter of 'it's good enough between SL ad 20000 ft'? The 2-stage engine will weight more, will have more drag, and will be bulkier. The USN already have had the F4U to cover high altitudes anyway. The F8F featured, vs. the Hellcat & Corsair, a smaller fuel tankage, smaller weight of armament, smaller fuselage and wings, so the single stage R-2800 was seen as a good fit.


Poster: KJ_Lesnick
Date: 11/24/2015
Time: 05:09:57

tomo pauk

QuoteThe engines, whether Cyclones or Twin wasps on the F4F, were always 2-speed supercharged. Most of the people don't separately state that any 2-stage engine have had an intercooler (reasoning it is understood as such)

So, it should be implied...

QuoteSometimes, the gearing on the 2-stage P&W engines is described as 3-speed, since the 1st stage could be de-clutched - only in low altitudes, where it is not needed, hence leaving more engine power to drive the prop.

Strange though the power-curves: Usually when there is a two-speed set-up, you usually see the brake horsepower staying about the same until you reach the critical altitude (true airspeed of course keeps going up), then you get a drop off in horse-power (and some speed falls off a little) until the next speed clutches on and then it stays there for awhile (true airspeed keeps on going up) and then above the critical it falls off and so on.

QuoteNo ww2 aircraft engine that matter used only 1-speed gearing when was outfitted with a gear-driven 2-stage supercharger

Was this because of the fact that you'd over-boost too easily?

Quotethe US engines did use 1-speed for engine-stage impellers, though (and multiple gears for 1st stage)

I'm not sure I understand you, I will try and make sure we're on the same page

• The US did use 1 speed for 1-stage superchargers in some cases
  
• The US did use 1 speed superchargers with 2 or more speeds in some cases
  

Am I right or wrong?

Quotethey did not featured both impellers on same drive shaft as it was common by RR 2-stage engines.

I was under the impression that the F4U was laid out like this, while I'm not sure here, my impression was as follows

• First stage supercharger is integral to the engine and single-speed and this is what they called "neutral blower".
  
• Second stage supercharger seems to be de-clutched at this point, and then is clutched into low and then high speed
  

I was under the impression that other than that (and possibly the P-63) they were tacked onto the same shaft.

QuoteThe sigle stage radial engine is very difficult to intercool/aftercool

Well technically the word intercooler/aftercooler are all based on their position: To have an intercooler you have to have at least two stages of compression as I understand it, it would be an after-cooler or pre-cooler otherwise.

Quotethere is no single intake manifold that leads from compressor to the cylinders.

You mean several airflow paths which go into each cylinder?

QuoteThe US 2-stage radials used intercooler to cool down the compressed air that went from 1-st stage to 2-nd stage of the compressor system.

Which makes sense: The key word being "inter" cooler, which means in between.

QuoteRR 2-stage engines cooled down the air/fuel mixture that went through both stages, one after another.

As I understand it the engine had an after-cooler that included cooling of the air-passageways between the first and second stage as well: An after-cooler that also doubled as an intercooler too...

QuoteWhy no 2-stage engines on the F7F (and F8F)? Probably a matter of 'it's good enough between SL ad 20000 ft'?

True, but for a WHIF design the F7F might very well have had the potential for a good escort: Consider the following

• The original intention was for Grumman to develop a twin-engined fighter that would be built for the Navy and the Army
  
• The USN version would use traditional supercharging, and an unpressurized cockpit; the USAAF version would be called the XP-65 and utilize a turbocharger and a pressurized cockpit (possibly differences in armament)
  
• The two designs grew so different that eventually the XP-65 was cancelled
  
• It should be noted that the USN's then design and the USAF's XP-65 were substantially different from the later F7F-1
  
• The USN continued to develop the design into the refined F7F-1
  
• While the P-38 was turbocharger-equipped, it was not often operated at the high-altitudes used for bomber escorts: The intercoolers and/or oil-coolers provided reliability issues and were damage-prone; though the P-38J did away with that, new problems popped up that took some time to be fixed
  
• An F7F-1 had a critical altitude of around 23,400 to 24,000 feet would be a little low for bomber escort (which would typically be around 25,500 to 31,500 feet, with a median of 28,500, being that 3,000 to 5,000 feet was favored over the bomber)
  
• The F7F-1 was more maneuverable than the P-38 (sans maneuvering flaps at least, and prior to the -J in terms of roll-rate at speed) and both had excellent climb-performance
  
• The baseline speed, and climb-rate performance of the F7F could be boosted by removing the tail-hook (which isn't needed for land-based operations), the wing-fold (un-needed for land-based operations)
  
• The baseline range performance could be improved without engine modification by doing the following: Removing the 4 x 20mm cannon and laying tankage in that area, and/or laying additional fuel-tankage outboard of the normal fold-line
  
• Engine improvements would drive up critical altitude however: Twin-stage, twin-speed with intercooler would do the job, alternately using a single-stage hydraulically clutched system (similar to the P-63) behind a single-speed integral supercharger with some form of cooling.
  

.

Poster: tomo pauk
Date: 11/24/2015
Time: 02:39:25

The reason people were using multi-speed supercharger drives is that this is a far more flexible thing then to have just one speed drive - it will suck less power down low (hence more power goes to the prop), while at higher altitudes the supercharger system will receive more power in order to improve the engine's power at the desired altitude range.
Overboosting was imited by throttling, in real world.

QuoteI'm not sure I understand you, I will try and make sure we're on the same page

....1# The US did use 1 speed for 1-stage superchargers in some cases
....2# The US did use 1 speed superchargers with 2 or more speeds in some cases

Am I right or wrong?

1# - Yes, vast majority of V-1710s, and all turbocharged and 2-stage engines were employing 1-speed drive for the intergral supercharger/impeller
2# - It is either one speed or two speed (or 3 speed like in Jumo 213E/F, or infinite number of speeds like in DB engines) drive, can't be both. Sometimes the drive for auxiliary supercrager of the 2-stage P&W engine was described as 3-speed: neutral (de-clutched), low gear, high gear.

QuoteI was under the impression that the F4U was laid out like this, while I'm not sure here, my impression was as follows

....1# First stage supercharger is integral to the engine and single-speed and this is what they called "neutral blower".
....2# Second stage supercharger seems to be de-clutched at this point, and then is clutched into low and then high speed

I was under the impression that other than that (and possibly the P-63) they were tacked onto the same shaft.

1# - As above, the term 'neutral' applies here on the auxiliary supercharger (1st stage). The integral supercharger (2nd stage) have had 1-speed drive and was always turning when engine was running.
2# - The auxiliary supercharger is the 1st stage here, and indeed was not clutched in in low altitude.

The auxiliary supercharger on the 2-stage V-1710s didn't share the drive, or the shaft with integral supercharger, but was provided with hydraulic coupling.

QuoteWell technically the word intercooler/aftercooler are all based on their position: To have an intercooler you have to have at least two stages of compression as I understand it, it would be an after-cooler or pre-cooler otherwise.

The term is based on the position of the observer - in the UK, people called the device 'inter-cooler' (as between supercharger and engine), the term 'after-cooler' (as after the supercharger) was mostly used in the USA.

QuoteYou mean several airflow paths which go into each cylinder?

Each cylinder has it's own intake manifold, going directly from supercharger.

QuoteTrue, but for a WHIF design the F7F might very well have had the potential for a good escort:

Agreed


Poster: KJ_Lesnick
Date: 11/24/2015
Time: 19:34:11

Tomo Pauk

QuoteThe reason people were using multi-speed supercharger drives is that this is a far more flexible thing then to have just one speed drive - it will suck less power down low (hence more power goes to the prop), while at higher altitudes the supercharger system will receive more power in order to improve the engine's power at the desired altitude range.

Correct, plus it's performance more closely mirrored a turbocharger.

Quote1# - Yes, vast majority of V-1710s, and all turbocharged and 2-stage engines were employing 1-speed drive for the intergral supercharger/impeller

Okay

Quote2# - It is either one speed or two speed (or 3 speed like in Jumo 213E/F, or infinite number of speeds like in DB engines) drive, can't be both.

Well, what I was trying to get at was all 2-speed superchargers were two-speed, but one stage superchargers could be one speed, two speed, etc.

QuoteSometimes the drive for auxiliary supercrager of the 2-stage P&W engine was described as 3-speed: neutral (de-clutched), low gear, high gear.

Okay, that I understand.

Quote2# - The auxiliary supercharger is the 1st stage here, and indeed was not clutched in in low altitude.

Now that is unexpected and I'd probably have to see it to visually grasp the layout though I grasp the basic idea.

QuoteThe auxiliary supercharger on the 2-stage V-1710s didn't share the drive

Why?

QuoteThe term is based on the position of the observer - in the UK, people called the device 'inter-cooler' (as between supercharger and engine), the term 'after-cooler' (as after the supercharger) was mostly used in the USA.

I thought it was relative to the impellers...

QuoteEach cylinder has it's own intake manifold, going directly from supercharger.

Got it

QuoteAgreed

I think the USAAF had too much of a predilection for turbochargers: I could understand with the B-17, B-24, and P-38, and P-47's: However it wasn't largely necessary for everything.


Poster: tomo pauk
Date: 11/24/2015
Time: 20:33:56

Quote from: KJ_Lesnick on November 24, 2015, 11:34:11 AM
Correct, plus it's performance more closely mirrored a turbocharger.

Generaly it did, if the supercharger was of 2-stage variety.

QuoteWell, what I was trying to get at was all 2-speed superchargers were two-speed, but one stage superchargers could be one speed, two speed, etc.

Yes, all 2-speed superchargers were two-speed  ;) The 2-stage superchargers have had multi-speed drives.

QuoteNow that is unexpected and I'd probably have to see it to visually grasp the layout though I grasp the basic idea.

Schematics of the supercharger system on the Hellcat: http://www.mediafire.com/view/wpz44qeyz01kdbq/stager.jpg# (http://www.mediafire.com/view/wpz44qeyz01kdbq/stager.jpg#)
The stages are numbered as the air (that they are supposed to compress) encounters them. Hence the auxiliary supercharger is the 1st stage, the integral (or main, or engine-stage) is the 2nd stage. Please note that, with auxiliary stage de-clutched (inoperative, 'neutral'), the air flow goes directly to the carburetor and then into the main stage.

Quote(The auxiliary supercharger on the 2-stage V-1710s didn't share the drive)Why?

No need, and it does not offer anything.  

QuoteI think the USAAF had too much of a predilection for turbochargers: I could understand with the B-17, B-24, and P-38, and P-47's: However it wasn't largely necessary for everything.

It was not used on everything - many important aircraft flew well without it, and so did the ones that used turbo :)


Poster: KJ_Lesnick
Date: 11/26/2015
Time: 04:56:38

Tomo Pauk

QuoteGeneraly it did, if the supercharger was of 2-stage variety.

Wait, if it was a supercharger (single speed) with a variable-speed tacked-on: Wouldn't it behave like a turbocharger with a supercharger too?

QuoteSchematics of the supercharger system on the Hellcat: http://www.mediafire.com/view/wpz44qeyz01kdbq/stager.jpg# (http://www.mediafire.com/view/wpz44qeyz01kdbq/stager.jpg#)
The stages are numbered as the air (that they are supposed to compress) encounters them. Hence the auxiliary supercharger is the 1st stage, the integral (or main, or engine-stage) is the 2nd stage.

Okay, I got it

QuotePlease note that, with auxiliary stage de-clutched (inoperative, 'neutral'), the air flow goes directly to the carburetor and then into the main stage.

Okay

QuoteNo need, and it does not offer anything.

Why did the British use them?

QuoteIt was not used on everything - many important aircraft flew well without it, and so did the ones that used turbo :)

Well... the following fighter-planes didn't

• P-36: They did toy with the idea of fitting a turbo in it, but it was unreliable
  
• P-40: It was mostly intended to operate around 15,000 feet and didn't require it
  
• P-39: It was intended to use a turbocharger, but it was removed for a number of reasons to the dismay of many who flew it
  
• P-51: It was developed by NAA internally, but was launched by the British Purchasing Commission and built around RAF specifications; it originally used a V-1710, and later a V-1650-3 or -7
  
• P-61: Though a night-fighter was seen as useful in the US, the aircraft was largely developed to RAF specifications for a turret night-fighter with an endurance of 8-hours; turbochargers were omitted to save weight and volume (it was realized it would add 50 mph and 10,000 feet altitude))
  
• P-63: It was basically built to correct the deficiencies of the P-39, and for obvious reasons they weren't going to use a turbocharger...
  
• P-75: It was basically a prototype and while the V-3420 was designed to carry a turbocharger, it didn't for some reason even when escort requirements were added: No idea of what kind of superchargers were used.
  

Regardless, the P-37 was fitted with one (even though it looked absurd and part of me speculates they built it largely to get a sufficient demand of V-1710's); the P-38's and P-47's had it, and the intention was for the P-39 to use it.

Pretty much all the attack planes didn't use it because they weren't designed for high altitude operation.

The bombers that didn't used them included

• The B-18
  
• The B-25
  
• The B-26
  

The B-18 was built in relatively small numbers and often used for missions at low altitudes such as MPA duty; the B-25 and B-26 were medium altitude planes; regardless, the B-17, B-24, B-29, the proposed XB-28, and B-36 all did; the XB-42 however didn't appear to


END CHRONICLE

I don't think an R-2800 turbo compound was ever available. It may have run on the test bench at or after the end of the war, but I'm not sure on that either.

The V-1710-127 did run in testing but did not fly. The issue with the -127 was that the turbine (an uprated turbine from a C-series turbocharger) coudl not cope with the exhaust gas temperatures at WEP, or possibly even Military power. Thus, if the turbo-compound V-1710 had continued in development it would have got a new, custom designed turbine with air cooled blades. As the Wright turbo-compound had when it appeared several years later.

wuzak

QuoteSimilar, but not the same.

Of course

QuoteThe variable speed drive had less of a range of rpm than the turbo, and the drive losses increased with altitude (as the compressor was spun faster to give a higher pressure ratio).

The graph would show a more gradual drop off in power than an engine with distinct supercharger gear ratios.

The lower range of RPM is of course a disadvantage, and while horsepower is taken off the shaft to drive the device at higher speeds, a variable not mentioned is exhaust thrust.  Though I wouldn't be surprised that turbochargers would still have some useful thrust that would be left over after it goes through the bucket-wheel (I don't know why they didn't just call it a turbine), though I'm not sure how much.  

It does seem to be noteworthy on a supercharger with good exhaust pipes as the exhaust does not go through any turbine and straight out: Provided the critical altitude can be kept high (dependent on the supercharger and ram-compression), you'd have potentially a hotter, faster, and higher pressure exhaust.  Above 350 mph or so, a pound of thrust is about the same as a pound of jet-thrust and at higher altitudes; the air-pressure is quite low so the exhaust would expand more forcefully against it.

QuoteThe way the V-1710 supercharger was set up was such that it was a bolt on.

Was this based on the idea of modularity, to make production simpler?

QuoteI take it what Tomo meant was that the two impellers were not mounted on the same shaft Rolls-Royce style. The reason being that you would end up with both impellers spinning at the same speed, and the variable speed function of the auxiliary supercharger would be lost.

Not if both superchargers were variable speed (I'm not sure how practical that would be admittedly)

QuoteThe reason why Rolls-Royce did it that way was because it was compact, and limited the extra length added to the engine.

How much extra length would a second stage add on the V-1710 out of curiosity?

QuoteReally? Or was this the XP-37, which was adapted from the P-36 to experiment with a V-1710/turbo combination?

There was the XP-37/YP-37, but there was also the Model 75R which was a P-36 with a turbocharger: It had a top-speed of 330 mph at some altitude allegedly, but it was overly complicated.

QuoteNot actually the case.

The turbo in the X/YP-37 was woefully unreliable, and created compromises that limited the practicality of the aircraft.

I'm surprised the XP-37/YP-37 got as far as it did: It's basic shape was almost comical.  I'm surprised somebody didn't realize that the design would be a disaster, who knows, maybe they did

QuoteDon Berlin, therefore, requested that a non-turbo V-1710 be provided, teh P-40 becoming a more practical and usable aircraft.

So the P-40 was built because the turbocharged YP-37 was impractical?

QuoteReally, source for that?

Well, I'm not sure how far along they got in the design, though they started whipping up the design in the summer of 1939 according to Joe Baugher's entry on the NA-73 (http://www.joebaugher.com/usaf_fighters/p51_1.html), and if I recall Paul A. Ludwig's book (P-51 Mustang: Development of the Long-Range Escort Fighter) made a reference of some of the basic fuselage and wing-design concepts already starting to be fleshed out (not sure if it's true admittedly).

QuoteIt may have also been thought that the extra speed was not required.

Unsure, to be honest: The only source of information that remotely mentioned the rationale for using a twin-stage supercharger over a turbocharger was Wikipedia (https://en.wikipedia.org/wiki/Northrop_P-61_Black_Widow).  A speed of around 365 mph would put it above most bombers of the era and if flying standing patrols it wouldn't have to accelerate as much or climb as much (if at all) to reach it's targets.

QuoteThe P-63 was built around the two stage V-1710.

As far as I know, the reason was because the turbocharger didn't work out: If it did, the P-63 would not have probably existed.  Still, while I'm at it, I'm curious when the twin-stage V-1710's were first underway in development and first available for operational use?

QuoteThe V-3420 was designed to have 1 stage supercharge, 1 stage supercharger with turbo or two stage supercharger.

The V-3420 would require two B-series turbochargers, the C-series not being large enough.

Like the B-29's?  How much space would two B-series turbos take up?

QuoteI believe the P-75 had two stage V-3420s.

Makes sense enough

QuoteAs I said above, the USAAC wanted to have a liquid cooled fighter (after seeing the Spitfire and Bf 109 performance)

Oh, that I understand.  Paul A. Ludwig's book on the P-51 seems to suggest that they procured it because it would create a demand for V-1710's, though it's possible they genuinely wanted a turbocharger driven fighter: However, it would not surprise me if they realized the design was impractical but continued to procure it because they figured it would create a demand for V-1710's.

Quotemiles per gallon x gallon = miles

Thanks

QuoteTomo talks of the charts in flight manuals that show fuel burn at different altitudes and engine settings (cruise speeds).

Just to be clear: When you say manual, do you meant the WWII aircraft performance page?  Otherwise, I don't have an F7F manual...

QuoteI don't think an R-2800 turbo compound was ever available. It may have run on the test bench at or after the end of the war, but I'm not sure on that either.

Oh


tomo pauk

QuoteSee what I've told you :)

Firstly: I should have clarified that they had a predilection for turbochargers when high altitude was sought out compared to the RAF, Luftwaffe, and US/Royal Navy.

QuoteGreat stuff about the reworked F7Fs.

Thanks

QuoteThe (obviously) US-produced bird for the USAF - can use 2-stage Packard Merlins (advantage vs. R-2800 is much more power above 20000 ft, less drag, greater mileage)

I'm looking at the power-curve chart for the P-51D-15NA, which was powered by a V-1650-7, and from what I'm seeing

• Altitude: 0';mn\. Setting: WEP;mmmnnn MAP: 67"; Supercharger: Low-Gear; Horsepower: 1630; Max TAS: 375 mph; K-Constant: 0.00003090962963
  
• Altitude: 0';mn\. Setting: Military;mmnn MAP: 61"; Supercharger: Low-Gear; Horsepower: 1500; Max TAS: 363 mph; K-Constant: 0.000031359662781
  
• Altitude: 0';mn\. Setting: Normal-Rated; MAP: 46"; Supercharger: Low-Gear; Horsepower: 1075; Max TAS: 323 mph K-Constant: 0.000031900750267
  
• Altitude: 5000';n Setting: WEP;mmmnnn MAP: 67"; Supercharger: Low-Gear; Horsepower: 1667; Max TAS: 396 mph; K-Constant: 0.000026844173806
  
• Altitude: 5000';n Setting: Military;mmnn MAP: 61"; Supercharger: Low-Gear; Horsepower: 1520; Max TAS: 382 mph; K-Constant: 0.000027268013429
  
• Altitude: 5000';n Setting: Normal-Rated; MAP: 46"; Supercharger: Low-Gear; Horsepower: 1105; Max TAS 342 mph; K-Constant: 0.000027623834274
  
• Altitude: 10000'; Setting: WEP;mmmnnn MAP: 67"; Supercharger: Low-Gear; Horsepower: 1700; Max TAS: 417 mph; K-Constant: 0.000023444488203; Notes: Critical Altitude (low-blower) on Wartime-Emergency Power
  
• Altitude: 10000'; Setting: Military;mmnn MAP: 61"; Supercharger: Low-Gear; Horsepower: 1545; Max TAS: 401 mph; K-Constant: 0.000023960471828
  
• Altitude: 10000'; Setting: Normal-Rated; MAP: 46"; Supercharger: Low-Gear; Horsepower: 1140; Max TAS: 362 mph; K-Constant: 0.000024031403732
  
• Altitude: 13200'; Setting: Military;mmnn MAP: 61"; Supercharger: Low-Gear; Horsepower: 1560; Max TAS: 413 mph; K-Constant: 0.000022144936709; Notes: Critical Altitude (low-blower) on Military-Power
  
• Altitude: 15000'; Setting: WEP;mmmnnn MAP: 57.7"; Supercharger: Low-Gear; Horsepower: 1480; Max TAS: 411 mph; K-Constant: 0.000021317498926
  
• Altitude: 15000'; Setting: Military;mmnn MAP: 57.8"; Supercharger: Low-Gear; Horsepower: 1475; Max TAS: 411 mph; K-Constant: 0.000021245480348; Notes: Interesting that there's more MAP in Military-Power than Wartime Emergency...
  
• Altitude: 15000'; Setting: Normal-Rated; MAP: 46"; Supercharger: Low-Gear; Horsepower: 1170; Max TAS: 382 mph; K-Constant: 0.000020989194547
  
• Altitude: 16200'; Setting: Normal-Rated: MAP: 46"; Supercharger: Low-Gear; Horsepower: 1175; Max TAS: 387 mph; K-Constant: 0.000020272390886; Notes: Critical Altitude (low-blower) on Normal-Rated Power
  
• Altitude: 20000'; Setting: WEP;mmmnnn MAP: 67"; Supercharger: High-Gear; Horsepower: 1410; Max TAS: 421 mph; K-Constant: 0.000018896128131
  
• Altitude: 20000'; Setting: Military;mmnn MAP: 61"; Supercharger: High-Gear; Horsepower: 1280; Max TAS: 410 mph; K-Constant: 0.000018571988218
  
• Altitude: 20000'; Setting: Normal-Rated; MAP: 40.5; Supercharger: Low-Gear; Horsepower: 1025; Max TAS: 384 mph; K-Constant: 0.000017748938666
  
• Altitude: 25000'; Setting: WEP;mmmnnn MAP: 67"; Supercharger: High-gear; Horsepower: 1410; Max TAS: 438 mph; K-Constant: 0.000016780186413
  
• Altitude: 25000'; Setting: Military;mmnn MAP: 61"; Supercharger: High-gear; Horsepower: 1285; Max TAS: 428 mph; K-Constant: 0.000016389730809
  
• Altitude: 25000'; Setting: Normal-Rated; MAP: 46"; Supercharger: High-Gear; Horsepower: 1025; Max TAS: 404 mph; K-Constant: 0.000015544607838
  
• Altitude: 26000'; Setting: WEP;mmmnnn MAP: 67"; Supercharger: High-Gear; Horsepower: 1410; Max TAS: 442 mph; K-Constant: 0.000016328726116; Notes: Critical Altitude (high-blower) on Wartime-Emergency Power; Maximum TAS
  
• Altitude: 28000'; Setting: Military;mmnn MAP: 61"; Supercharger: High-Gear; Horsepower: 1288; Max TAS: 438 mph; K-Constant: 0.000015328283759; Notes: Critical Altitude (high-blower) on Military Power
  
• Altitude: 29400'; Setting: Normal-Rated; MAP: 46"; Supercharger: High-Gear; Horsepower: 1040; Max TAS: 420 mph; K-Constant: 0.000014037360976; Notes: Critical Altitude (high-blower) on Normal-Rated Power
  
• Altitude: 30000'; Setting: Military;mmnn MAP: 54.5"; Supercharger: High-Gear; Horsepower: 1180; Max TAS: 429 mph: K-Constant: 0.000014945489052; Notes: WEP and Military-Power appear to be the same in terms of speed, horsepower, and MAP from this altitude on...
  
• Altitude: 30000'; Setting: Normal-Rated; MAP: 44.7"; Supercharger: High-Gear; Horsepower: 1010; Max TAS: 416 mph; K-Constant: 0.000014029473785
  
• Altitude: 35000'; Setting: Military;mmnn MAP: 43"; Supercharger: High-Gear; Horsepower: 900; Max TAS: 407 mph; K-Constant: 0.000013349324242
  
• Altitude: 35000'; Setting: Normal-Rated: MAP: 35"; Supercharger: High-Gear; Horsepower: 765; Max TAS: 388 mph; K-Constant: 0.000013096832053
  

The tests that confirmed these figures were based upon a weight of 9760 lbs.

Looking at the figures for the F7F-1 show at 20,000 feet, a horsepower of 1600 per engine at military power (compared to 1280 hp figure for the V-1650-7 at the same power setting and altitude; furthermore even at WEP at critical altitude of 26000 in high-gear, yields a horsepower of 1410).  An inline would, admittedly be nice from the standpoint of drag, however the only inlines I can readily think of that produced similar power would be the following

• Napier Sabre (2180 to 2260 hp): I'm not sure if they were produced in the United States and I'm not sure the supercharging details
  
• Rolls-Royce Griffon (1490 hp to 2420 hp): The upper power-levels may or may not have been produced prior to November 3, 1943
  
• Allison V-3420 (2600 to 2800 hp): It was available on time, and wouldn't be bad for an up-rated version, though (could be a good alternate for the P-75 though).
  

The Allison V-3420 does seem like a pretty cool idea, but the R-2800 may very well have delivered acceptable performance if critical altitude could be kept up higher

Quotenot using and intercooler means easier installation

I'm confused here: Last I checked, the F7F had a pair of intakes in each wing.  I'm not sure the exact function of each intake, though an engine air-intake and oil-cooler would be good candidates: The F4U's interestingly used a set of intakes for both the oil-cooler and air-intake (I think...)

QuoteOne set of graphs is for the air speed, another set of graphs is for rate of climb.

You mean this one?

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi64.tinypic.com%2F29bfxns.png&hash=31360dfcc03a62b0aa9ae5e2af6ac672c55c1665)

Yep - the graph states the velocity in mph and rate of climb in fpm.
The intakes on the F7F indeed served as you stated - one is feeding the sir to the engine itself, another one serves the oil cooler. Going with a liquid cooled engine obviously necessitates the cooler for gylcol/water mixture, if the engine is intercooled then another cooler is needed, at least for Anglo-American engines.

QuoteLooking at the figures for the F7F-1 show at 20,000 feet, a horsepower of 1600 per engine at military power (compared to 1280 hp figure for the V-1650-7 at the same power setting and altitude; furthermore even at WEP at critical altitude of 26000 in high-gear, yields a horsepower of 1410).

The engine powers need to be compared without the ram effect. The R-2800-22W have had 1850 HP at 14000 ft, 1600 HP at 16000 ft, that would make maybe 1400 Hp at 20000 ft, and 1100-1200 HP at 25000 ft. Ram effect (most pronounced at high speed) will add some 5000 ft to the listed altitudes in these cases (both P&W and P. Merlin).
The 2-stage Packard Merlin will match that power from 20000 ft and above, that coupled with lower powerplant drag will make such an engined F7F outpacing and outclimbing the historic F7F above 20000 ft, let alone above 25000 ft. The V-1650-7 was available maybe 10 months earlier than the R-2800-22W, that is also a major point of difference historically, another bonus being maybe 20% increase in range/radius. In early 1945, the V-1650-9 will further improve the power figures of the Packard Merlin line of engines, basically beating the -22W (and -34W) already above 15000 ft; same will happen with V-1650-7 when operating on 150 or 145 grade fuel.
The 2-stage V-1710 will also match the power of the -22W by the time the -22W is available (mid-late 1944) above 20000 ft.

As for the alternatives you mentioned - all will work fine in an what-if. Realistically, either Sabre or Griffon (but they are only Made in UK); the V-3420 is too heavy.

QuoteFirstly: I should have clarified that they had a predilection for turbochargers when high altitude was sought out compared to the RAF, Luftwaffe, and US/Royal Navy.

The predilection for turbochargers was shared between the US Army and VVS, the LW and RN were firmly in single stage engines camp (and VVS once the experiments with turbo were sidetracked, hence the AM 34 to 37 series of engines, plus the experiments with turboed Mikulin engines), RAF and USN indeed jumped at the chance to have 2-stage engines once available. All said is for the time between mid-1930s to mid war.

wuzak said:

QuoteI don't think an R-2800 turbo compound was ever available. It may have run on the test bench at or after the end of the war, but I'm not sure on that either.

The V-1710-127 did run in testing but did not fly. The issue with the -127 was that the turbine (an uprated turbine from a C-series turbocharger) coudl not cope with the exhaust gas temperatures at WEP, or possibly even Military power. Thus, if the turbo-compound V-1710 had continued in development it would have got a new, custom designed turbine with air cooled blades. As the Wright turbo-compound had when it appeared several years later.

The turbo-compound R-2800 will work as an what if :)
Turbine on the TC V-1710 was probably too close to the cylinders - several feet? With the turbine in one end of nacelle and engine on another, the temperature peaks should be kept under control, we can recall that same turbine have had no problems on the P-47. Indeed for the close coupled turbine the air cooled blades are necessity.

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi200.photobucket.com%2Falbums%2Faa263%2Fkitnut617%2FMisc%2520Photos%2Fpecher_zpsujo82ei4.gif&hash=0346ab3c184e9edb9cc31a398816cef5d92da322) (http://s200.photobucket.com/user/kitnut617/media/Misc%20Photos/pecher_zpsujo82ei4.gif.html)

The Curtiss Hawk 75R had an auxiliary mechanical supercharger, not a turbo-supercharger.

Apart from obvious, for a what-if, engine change to a V-12, the jet engined F7F will be one sleek machine. The U/C might be retracted next to the jet engine, or alternatively the main legs will retract in the fuselage, in a layout of F-104, or XB-42 or Yak-38. Other option might include the turbo prop.

What was basically an enlarged jet-engined F7F was looked at for the role eventually filled by the Douglas F3D.

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi729.photobucket.com%2Falbums%2Fww291%2Fjoncarrfarrelly%2FBTS%2FDES_75_XF9F_01.jpg&hash=d83ffa1eff97429079c3b62f4d282c041d9774b4)

Many thanks :)

Quote from: kitnut617 on November 28, 2015, 08:59:11 AM
(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi200.photobucket.com%2Falbums%2Faa263%2Fkitnut617%2FMisc%2520Photos%2Fpecher_zpsujo82ei4.gif&hash=0346ab3c184e9edb9cc31a398816cef5d92da322) (http://s200.photobucket.com/user/kitnut617/media/Misc%20Photos/pecher_zpsujo82ei4.gif.html)

Nice  ;)

reeled one in....

tomo pauk

QuoteYep - the graph states the velocity in mph and rate of climb in fpm.

Okay, that makes more sense

QuoteThe intakes on the F7F indeed served as you stated

Honestly jet-engines are so much easier to grasp LOL

QuoteGoing with a liquid cooled engine obviously necessitates the cooler for gylcol/water mixture

Correct

QuoteIf the engine is intercooled then another cooler is needed, at least for Anglo-American engines.

Actually, the F4U used the same intake to feed the oil-cooler and intercooler right?  Would that work in some arrangement here by doing one of the following

• Add a scoop under the engine like the F4U-4
  
• Enlarging the oil-cooler either in width, depth, or some combo of both
  
• Repositioning the intakes
  

I'm not sure which intake was the cooler and which was the intake.

QuoteThe engine powers need to be compared without the ram effect. The R-2800-22W have had 1850 HP at 14000 ft, 1600 HP at 16000 ft, that would make maybe 1400 Hp at 20000 ft, and 1100-1200 HP at 25000 ft. Ram effect (most pronounced at high speed) will add some 5000 ft to the listed altitudes in these cases (both P&W and P. Merlin).

I thought the figures on the speed/horsepower chart were based on ram being present (after all, the P-51's HP keeps going up a bit)

QuoteThe V-1650-7 was available maybe 10 months earlier than the R-2800-22W, that is also a major point of difference historically, another bonus being maybe 20% increase in range/radius.

When was the R-2800-18W and 22W available?

QuoteAs for the alternatives you mentioned - all will work fine in an what-if.

Of course, and I of course explained why they weren't feasible.  I never gave the weight of the V-3420 much thought but I figure the engine was pretty close to the CG

QuoteThe predilection for turbochargers was shared between the US Army and VVS

I didn't know the Russians did much work on turbochargers, was the turbocharger work sidetracked due to Stalin's purges?

Quotethe LW and RN were firmly in single stage engines camp

If I recall some Seafires had twin-stage superchargers...

QuoteRAF and USN indeed jumped at the chance to have 2-stage engines once available. All said is for the time between mid-1930s to mid war.

That looks right...


joncarrfarrelly

QuoteThe Curtiss Hawk 75R had an auxiliary mechanical supercharger, not a turbo-supercharger.

Whoops!

QuoteWhat was basically an enlarged jet-engined F7F was looked at for the role eventually filled by the Douglas F3D.

It seems by that point you'd be better off just procuring a new plane, I don't know what the mach limits of the F7F's wings were...

Quote from: sandiego89 on November 29, 2015, 01:22:25 PM

Quote from: kitnut617 on November 28, 2015, 08:59:11 AM
(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi200.photobucket.com%2Falbums%2Faa263%2Fkitnut617%2FMisc%2520Photos%2Fpecher_zpsujo82ei4.gif&hash=0346ab3c184e9edb9cc31a398816cef5d92da322) (http://s200.photobucket.com/user/kitnut617/media/Misc%20Photos/pecher_zpsujo82ei4.gif.html)

Nice  ;)

reeled one in....

Seems to be using good bait, wonder what it is?  ;)

Quote from: kitnut617 on November 28, 2015, 08:59:11 AM(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2Fi200.photobucket.com%2Falbums%2Faa263%2Fkitnut617%2FMisc%2520Photos%2Fpecher_zpsujo82ei4.gif&hash=0346ab3c184e9edb9cc31a398816cef5d92da322) (http://s200.photobucket.com/user/kitnut617/media/Misc%20Photos/pecher_zpsujo82ei4.gif.html)

Are you accusing one of us of trolling?

Because last I checked we had a decent discussion going over here...

Quote from: KJ_Lesnick on November 29, 2015, 07:21:25 PM

Actually, the F4U used the same intake to feed the oil-cooler and intercooler right?  Would that work in some arrangement here by doing one of the following

• Add a scoop under the engine like the F4U-4
  
• Enlarging the oil-cooler either in width, depth, or some combo of both
  
• Repositioning the intakes
  

I'm not sure which intake was the cooler and which was the intake.

Each intake in the F4U-1 provided the air for 3 'things':
- oil coolers
- intercoolers
- engine itself

The F4U-4 indeed added the under-engine scoop that fed the engine (hence leaving the wing intakes' air just for oil coolers and itercoolers) , the -5U have had 2 'cheek' intakes, one per each of the 'Sidewinder' compressors that provided the compressed air to the engine-stage compressor.

QuoteI thought the figures on the speed/horsepower chart were based on ram being present (after all, the P-51's HP keeps going up a bit)

The reason why the engine power of the P-51D keeps going up is the presence of two stage compressor. BTW, the military power of the P-51D was 1370 HP at 21400 ft, WER was 1500 HP at 19300 ft, no ram - there is no way that either R-2800-22W or -34W will come close in power vs. drag here. On 150 grade fuel, WER was 1800 HP at 12000 ft.

QuoteWhen was the R-2800-18W and 22W available?

The 1st F4U-4 (ie. with -18W, the 2-stage 'C' series R-2800 as it was the single stage -22W) was delivered by December 1944. Don't know yet about the F7F. The 1st P-51D was delivered by January 1944.

QuoteI didn't know the Russians did much work on turbochargers, was the turbocharger work sidetracked due to Stalin's purges?

Purges have had next to no development on that. Soviets probably came to the same conclusions as the USAC once the ww2 started in 1939 - they set for non-turbo engines for the reson they could have those in numbers. Once the air war in the East turned into mostly low altitude campaign, the emphasis onn turbo was even more sidetracked.

QuoteIf I recall some Seafires had twin-stage superchargers...

Not by mid war... :)

Quote from: tomo pauk on November 30, 2015, 02:04:19 AM

QuoteIf I recall some Seafires had twin-stage superchargers...

Not by mid war... :)

Not at all during the war!

tomo pauk

QuoteEach intake in the F4U-1 provided the air for 3 'things':
- oil coolers
- intercoolers
- engine itself

I didn't actually know that, though I suppose it makes sense as I didn't see intakes anywhere else.

As for the F7F: Which intake is the oil-cooler?

QuoteThe F4U-4 indeed added the under-engine scoop that fed the engine (hence leaving the wing intakes' air just for oil coolers and itercoolers)

I assume it meant more air could be used for oil cooling and intercooling?

QuoteThe reason why the engine power of the P-51D keeps going up is the presence of two stage compressor.

Did the RR Merlin bypass one of the stages?

QuoteBTW, the military power of the P-51D was 1370 HP at 21400 ft, WER was 1500 HP at 19300 ft, no ram

I'm not sure what octane was used in the test data that I have, and at some point they boosted to 75"

Quotethere is no way that either R-2800-22W or -34W will come close in power vs. drag here.

I'll give you that, but the power is useful at lower-speeds...

QuoteThe 1st F4U-4 (ie. with -18W, the 2-stage 'C' series R-2800 as it was the single stage -22W) was delivered by December 1944.

I understand the dates, but I'm curious if I understand the rest: The -18W was a twin-stage version of the -22W?

QuotePurges have had next to no development on that. Soviets probably came to the same conclusions as the USAC once the ww2 started in 1939 - they set for non-turbo engines for the reson they could have those in numbers.

So turbos were harder to mass produce?

QuoteNot by mid war... :)

So that came later...

The inboard intake was for the oil cooler. The exit of the air was through a flap at upper wing surface, can be seen here: https://upload.wikimedia.org/wikipedia/commons/2/28/F7F_Tigercat_N747MX_La_Patrona_2014_Reno_Air_Races_Silver_photo_D_Ramey_Logan.jpg (https://upload.wikimedia.org/wikipedia/commons/2/28/F7F_Tigercat_N747MX_La_Patrona_2014_Reno_Air_Races_Silver_photo_D_Ramey_Logan.jpg)

QuoteI assume it meant more air could be used for oil cooling and intercooling?

Indeed.

QuoteDid the RR Merlin bypass one of the stages?

No.

QuoteI'm not sure what octane was used in the test data that I have, and at some point they boosted to 75"

On 130 grade fuel - up to 67 in Hg  for both V-1650-3 and -7 (1500 HP at 19300 ft for the -7). Above that manifold pressure the 150 grade fuel must be used.

QuoteI'll give you that, but the power is useful at lower-speeds...

It's always useful :)

QuoteI understand the dates, but I'm curious if I understand the rest: The -18W was a twin-stage version of the -22W?

Both -18W and -22W, plus -34W and -57 (that was supported by turbo) were the 'members' of the 'C' series R-2800 engines. Don't think that we can talk about the -18W being a version of the -22.
The post-war 'E' series featured, for example, -30W (1-stage) and -32 (but still with water injection, 2-stage but with 3 impellers).

QuoteSo turbos were harder to mass produce?

Harder than what? As for the turbos themselves, it depends what country we're talking about. The USA produced them in tens of thousands - they have had enough of money and industrial capacity to do so. Soviets were not in that position, especially once the Germans invaded. The 3 main types of Soviet engines (Mikulin, Klimov, 14 cyl Shvetsov) were produced in maybe 4-5 factories (Mikulin in just one?), comparing with R-2800, R-2600, V-1710 and V-1650 being produced in 10-12 factories.

tomo pauk

QuoteThe inboard intake was for the oil cooler. The exit of the air was through a flap at upper wing surface, can be seen here: https://upload.wikimedia.org/wikipedia/commons/2/28/F7F_Tigercat_N747MX_La_Patrona_2014_Reno_Air_Races_Silver_photo_D_Ramey_Logan.jpg (https://upload.wikimedia.org/wikipedia/commons/2/28/F7F_Tigercat_N747MX_La_Patrona_2014_Reno_Air_Races_Silver_photo_D_Ramey_Logan.jpg)

Now that's a beautiful picture: Because the oil-cooler goes straight through in the way it does I would assume it would be unsuitable for being used as an intercooler?  Would the outboard intake suffice?

QuoteIndeed.

Makes sense

QuoteNo.

Well if the RPM is tied to a gear ratio it's RPM would be dependent on whatever the engines was correct?

QuoteOn 130 grade fuel - up to 67 in Hg  for both V-1650-3 and -7 (1500 HP at 19300 ft for the -7). Above that manifold pressure the 150 grade fuel must be used.

Understood

QuoteIt's always useful :)

Yup, though at high altitude it makes little difference evidently

QuoteBoth -18W and -22W, plus -34W and -57 (that was supported by turbo) were the 'members' of the 'C' series R-2800 engines.

Okay, so they were all part of the same line

QuoteHarder than what? As for the turbos themselves, it depends what country we're talking about.

So it's a matter of industrial capacity?

Yes - if the industry cannot churn them (or anything) during a major war, then it does not matter what have the engineers come out with.

QuoteBecause the oil-cooler goes straight through in the way it does I would assume it would be unsuitable for being used as an intercooler?  Would the outboard intake suffice?

Hmm - actualy, the oil cooler 'tunnel' might suffice for the needs of intercooler for the V-12 of the era. The air intake will go either under (Merlin) or above engine (V-1710), leaving the outboard intake for the intercooler; obviously, the air need to exit somewhere, too, so that will need to have it. The cooler(s) for the engine can go into the 'beard', under the engine itself.

QuoteWell if the RPM is tied to a gear ratio it's RPM would be dependent on whatever the engines was correct?

Yes.

I can't find a really good picture of it, but teh B-17's intercooler was fed by one of the leading edge ducts, and the air left by pone of the slots on teh wing

http://s568.photobucket.com/user/bgorin/media/B17IntercoolerIPC.png.html

http://www.air-and-space.com/20050510%20Santa%20Maria/DSC_0433%20B-17G%20N93012%20Nine-O-Nine%20left%20wing%20l.jpg

KJ asked about the Mach limit of the F7F. I have some dive limit numbers, should give us the ballpark.
In the manual for the F7F-1, the limit of indicated air speed at 30000 ft was 300 kts (345 mph), thus soundly beating the P-38 redlined at 290 mph at same altitude. 290 mph IAS at 30000 ft works as 440 mph true air speed. Interestingly enough, the wing profile of the F7F was just a tad thinner than of the P-38 - NACA 23015 vs. 23016 (values for the root).
The P-51, one of the best divers due to the laminar flow wing, was redlined at 340 mph IAS (P-51B) at 30000 ft, and 325 mph (P-51D). The P-47N was at 318 mph IAS at 30 kft.

tomo pauk

QuoteHmm - actualy, the oil cooler 'tunnel' might suffice for the needs of intercooler for the V-12 of the era.

Except the R-2800 isn't a V-12... I'm not interested in the V-1650/V-1710 idea as you'd have less power at low altitude (plus keeping the radial is better from the standpoint of damage resistance).

QuoteThe cooler(s) for the engine can go into the 'beard', under the engine itself.

Or in this case like the F4U-4's layout...

QuoteYes.

Then why would the horsepower keep going up?  On at least some charts: Power stays around a certain amount; then falls off.  The only thing I can think of would be

• Failure to factor in a normal increase in HP as speed goes up
  
• Ram compression
  
• The factoring of exhaust into the HP: At 350 mph 1 hp = 1 lbf
  

QuoteKJ asked about the Mach limit of the F7F. I have some dive limit numbers, should give us the ballpark.
In the manual for the F7F-1, the limit of indicated air speed at 30000 ft was 300 kts (345 mph), thus soundly beating the P-38 redlined at 290 mph at same altitude. 290 mph IAS at 30000 ft works as 440 mph true air speed.

Hmmm, I'm not getting the same numbers here

I have a mach/airspeed chart readily available and here's what I got for the chart

........TAS @ Mach 1..........IAS @ Mach 1...........Altitude

• 661.5 kt/761.2 mph...661.5 kt/761.2 mph...0'
  
• 650.0 kt/748.0 mph...650.0 kt/706.0 mph...5000'
  
• 638.3 kt/734.6 mph...566.3 kt/651.7 mph...10000'
  
• 626.5 kt/721.0 mph...520.1 kt/598.6 mph...15000'
  
• 614.3 kt/707.0 mph...475.2 kt/546.9 mph...20000'
  
• 602.0 kt/692.8 mph...431.8 kt/496.8 mph...25000'
  
• 589.4 kt/678.3 mph...389.7 kt/448.4 mph...30000'
  
• 576.5 kt/576.5 mph...350.0 kt/402.8 mph...35000'
  

.
Based on these figures

• 290 mph indicated at 30,000 feet comes out to 438.7 mph true, or Mach 0.65 for the P-38
  
• 318 mph indicated at 30,000 feet comes out to 481 mph true, or Mach 0.71 for the P-47N
  
• 340 mph indicated at 30,000 feet comes out to 514.3 mph true, or Mach 0.76 for the P-51B
  
• 325 mph indicated at 30,000 feet comes out to 491.6 mph true, or Mach 0.72 for the P-51D
  
• 345 mph indicated at 30,000 feet comes out to 521.9 mph true, or Mach 0.77 for the F7F-1
  

Some of these numbers seem suspect as the speed where mach effects start to kick in on the P-38 is generally listed at 0.67-0.68 with the airplane out of control by 0.74; the listed mach number at which the P-47 usually seems to encounter Mach effects are around 0.67 though it seems to retain a degree of maneuverability to 0.72, and I'm uncertain at what speed control is lost.  

I'm not sure when the P-51 started encountering mach effects, though I remember hearing that it the aircraft's maximum safe diving speed was 0.84, though I'd almost swear I heard 0.85 mentioned once; the Spitfire's maximum safe diving speed was Mach 0.85, though speeds ranging from 0.891 to 0.94 were achieved :blink:

QuoteInterestingly enough, the wing profile of the F7F was just a tad thinner than of the P-38 - NACA 23015 vs. 23016 (values for the root).

At the penalty of sounding stupid: Is that the P-38 or F7F figures you're listing?


wuzak

QuoteI can't find a really good picture of it, but teh B-17's intercooler was fed by one of the leading edge ducts, and the air left by pone of the slots on teh wing

http://s568.photobucket.com/user/bgorin/media/B17IntercoolerIPC.png.html

Both have a similar offset, so I suppose one could theoretically use the oil-cooler as an intercooler

I am interested in the V-12 powered F7F, even if just as a mental excesise - a what-if :) Hence finding the more or less a convinient way to install the intercooled Packard Merlin on it. Good deal of the lack of power down low will be cancelled by the lower drag, and the F7F powered by V-1650-9 will probably be faster than the historic F7F at any altitude.

QuoteThen why would the horsepower keep going up?

It will go a bit up with altitude due to the lower back-pressure the exhaust must overcome, up until the the critical altitude for the observed gear the compressor is currentl using, for a current engine power setting. Also the ever cooler air helps. The power with ram is not always listed in engine charts, though some power charts and tables have it (like for the Jumo 210/211 or some US engines). Nobody was calculating the exhaust thrust into the power with intent to add it to the engine power, though some charts do show either thrust as force or as power (like it was the case for the docs about DB 601A/Aa or BMW 801D).

Tomo, I believe the intake below the spinner on teh 2 stage Mosquitoes was for teh intercooler.

http://www.ausairpower.net/APAA/DH-Mosquito-PR-XVI-071017-F-1234S-017-1S.jpg

The exit is on the side of the nacelle, above where the carb intake is.

Yes, in case of Mosquito with 2-stage engine the intercoolers were just under the spinner.

tomo pauk

QuoteI am interested in the V-12 powered F7F, even if just as a mental excesise - a what-if :)

Okay

QuoteIt will go a bit up with altitude due to the lower back-pressure the exhaust must overcome, up until the the critical altitude for the observed gear the compressor is currentl using, for a current engine power setting.

So back-pressure affects superchargers too?

QuoteAlso the ever cooler air helps.

Makes enough sense

QuoteThe power with ram is not always listed in engine charts

Weird...

QuoteNobody was calculating the exhaust thrust into the power with intent to add it to the engine power, though some charts do show either thrust as force or as power (like it was the case for the docs about DB 601A/Aa or BMW 801D).

Frankly, I think it should be counted as thrust, not as HP to be honest.


wuzak

QuoteTomo, I believe the intake below the spinner on teh 2 stage Mosquitoes was for teh intercooler.

http://www.ausairpower.net/APAA/DH-Mosquito-PR-XVI-071017-F-1234S-017-1S.jpg

The exit is on the side of the nacelle, above where the carb intake is.

Understood

The back pressure does not effect effect the superchargers.

Listing the power vs. altitude without ram effect accounted for makes lots of sense, since that altitude depends on plenty of factors. Like the layout of ram air intake ( eg. the well executed in the P-40, Mosquito, P-51 and Bf 109 vs. badly executed in P-39 and Whirlwind; squished air intake on the Fw 190A that sucks the turbulent air vs. the 'full profile' external air intakes in a handful of such outfitted Fw 190As) and real air speed an aircraft powered with such an engine can make (faster P-51 vs. slower P-40). Having a better carb also helps (see tests of Spitfire with injection carb vs. float carb); the ice or stone guard presence or absence also makes difference in altitude power of an engine.

Entirely off topic and unrelated to F7F but the guys to impress are of the kind that trolled Bill Gunston for daily fun. It starts when some guy sort of proved that it was Gunston who coined the phrase the Harrier could carry a box of matches across a football field. Gunston swore vengeance and played as if he took the bait. For 26 years they promised to sell a flying saucer to him and he played it in the stoical British way of doing stuff, expecting to expose them as frauds. Good hunting!

tomo pauk

QuoteThe back pressure does not effect effect the superchargers.

So you're talking about the exhaust having less resistance as it shoots out the stacks?

QuoteListing the power vs. altitude without ram effect accounted for makes lots of sense, since that altitude depends on plenty of factors. Like the layout of ram air intake ( eg. the well executed in the P-40, Mosquito, P-51 and Bf 109 vs. badly executed in P-39 and Whirlwind; squished air intake on the Fw 190A that sucks the turbulent air vs. the 'full profile' external air intakes in a handful of such outfitted Fw 190As) and real air speed an aircraft powered with such an engine can make (faster P-51 vs. slower P-40). Having a better carb also helps (see tests of Spitfire with injection carb vs. float carb); the ice or stone guard presence or absence also makes difference in altitude power of an engine.

So it gives a baseline figure for the engine and also helps gauge what performance you'll get based on speed?

tomo pauk & wuzak

I found something I think everybody here will like: A cutaway!

(https://www.whatifmodellers.com/proxy.php?request=http%3A%2F%2F4.bp.blogspot.com%2F-jKiVwn9yfnY%2FU9pp5OT9I2I%2FAAAAAAABJ2A%2FK1kv4TxYRu0%2Fs1600%2F14-d79dbb2bf2.jpg&hash=5c787a40624834d8181a451bdb193d22380f34fc)

As for the purposes of a land-based escort-fighter/fighter-bomber design: Would the following traits provide sufficient range

• Drop tanks
  
• A twin-stage supercharger with one stage being twin-staged, and the other being variable-speed (i.e. F4U-4)
  
• Doing one of the following: Enlarging the oil-cooler intake to work as an intercooler; adding an F4U-4 style intake under the engine to serve as a carburetor intake, with the previous carburetor intake to provide the intercooling; other
  
• Removing the wing-fold mechanism
  
• Laying fuel-bladders/tanks across parts of the leading-edge where permissable and/or the outboard wing area
  

.

As another interesting note: This is a quote from joncarrfarrelly and suggests another interesting possibility...

QuoteThe Army XP-65 wasn't actually a variation of the USN F7F, both were iterations of Design 51.

The story starts with the Grumman Design 46 of October 1939, a large twin 1,600hp R-2600 powered aircraft (two-stage mechanical superchargers or turbo-superchargers) for the Army. A derivative was offered for export in February 1940 as the Design 49.
The preliminary design work for these two projects worked to Grumman's advantage when they decided to submit a proposal to a 21 December, 1940 RFP for specification SD-112-18. Seeking to satisfy both Army and Navy requirements, Grumman incorporated most features of Designs 46 and 49 into the Design 51 proposal, which was submitted to BuAer 24 March, 1941, and emerged as the winner of the Navy competition on 14 May. By then the Army and Navy and had agreed to seek the development of twin-engined fighters differing only in details, the Army opted for turbo-superchargers, the Navy for mechanical superchargers. The Army version was to be pressurized and armed with two 37mm cannon and four .50 MG, whereas the Navy version was to be unpressurized and armed with four 20mm cannon in place of the two 37mm weapons.

The aircraft originally started out as a USAAC design, which was then developed into a USN & USAAC design, which the USAAC/USAAF dropped out of and the USN then modified further into the F7F-1.

Since SD-112-18 was a USN specification: I assume the USAAC hadn't fully signed off on the program by this point?  From a WHIF-standpoint: What if they did?

I wonder how far back the idea of building one aircraft to satisfy both the Army and the Navy goes back to? Appears to fail even back in 1941.

Quote from: kerick on January 27, 2016, 08:01:12 PM
I wonder how far back the idea of building one aircraft to satisfy both the Army and the Navy goes back to? Appears to fail even back in 1941.

It appears to have worked for the RN FAA and the RAF.  The problem is, neither the USN or USAF want it to work... :banghead: :banghead:

Quote from: KJ_Lesnick on January 27, 2016, 04:22:13 PM...
As for the purposes of a land-based escort-fighter/fighter-bomber design: Would the following traits provide sufficient range

• Drop tanks
  
• A twin-stage supercharger with one stage being twin-staged, and the other being variable-speed (i.e. F4U-4)
  
• Doing one of the following: Enlarging the oil-cooler intake to work as an intercooler; adding an F4U-4 style intake under the engine to serve as a carburetor intake, with the previous carburetor intake to provide the intercooling; other
  
• Removing the wing-fold mechanism
  
• Laying fuel-bladders/tanks across parts of the leading-edge where permissable and/or the outboard wing area
  

...

Drop tanks are no-brainer, they are already supported.
In supercharger, one stage can't be twin-staged. In F4U-4, main, or engine stage was 1-speed (= fixed gearing), the auxiliary stage was 2-speed, that can be declutched, 'behaving' like it is 3-speed. No need to reinvent the wheel, use the 2-stage R-2800 that is currently available. The change from 1-stage R-2800 to 2-stage will make next to no change on range/radius.
Oil cooler won't help with intercooling, those are two separate systems. Perhaps use straight tunnel for the oil cooler instead the 'S' shaped one, so the intercooler can be located nearby the engine in the wing.
Leading edge won't be a good place for extra fuel tanks, it already is occuied with different intakes and cannon ports. Use the space between the spars instead.
Fixed wings are good idea.

Quote from: tomo pauk on January 30, 2016, 05:02:09 PMDrop tanks are no-brainer, they are already supported.

Yup

QuoteIn supercharger, one stage can't be twin-staged.

Yes, but you could replace the single staged arrangement with a twin-staged layout...

QuoteIn F4U-4, main, or engine stage was 1-speed (= fixed gearing), the auxiliary stage was 2-speed, that can be declutched, 'behaving' like it is 3-speed. No need to reinvent the wheel, use the 2-stage R-2800 that is currently available.

I thought the F4U-4 had a hydraulic clutch system on one stage?

QuoteThe change from 1-stage R-2800 to 2-stage will make next to no change on range/radius.

Why?

QuoteOil cooler won't help with intercooling

No!  I was trying to figure out where to supply the air for an intercooler.  I don't care where it comes from so long as it's there.

QuoteLeading edge won't be a good place for extra fuel tanks, it already is occuied with different intakes and cannon ports. Use the space between the spars instead.

Okay

Replacing an existing supercharger system on an engine already installed in an aircraft, if that's your intention, is reinventing the wheel, or a recipe for problems, or both. The R-2800 was available in 1942 in 2-stage supercharged form, so let's use what is available.
The R-2800-18 indeed have had hydrauilcal clutch for auxiliary stage, thing being that speed ratios were pre-set, there was no variation of speed like it was the case with Allison take on the same problem.
R-2800 was still a powerful engine, and a fuel hog. Want more range? Increase fuel tankage. Let's remeber that P-47 was good for 450 miles of combat radius (not range, that was greater of course) with 300 gals internaly plus 300 gals externally; 600 miles with 370 + 300 gals, 1000 miles with 556 + 600 gals. F6F was under 300 miles, it carried 250 gals internally
So unless we have the F7F with at least 700 gals internally (two engines to feed...), plus 600 gals externally, it wont be much of a long range fighter, at least not under USAF conditions, that were demanding much greater cruise speed and altitude than USN conditions. Perhaps it would be a good idea to get rid of .50s and their ammo, cram more fuel there.

tomo pauk

QuoteReplacing an existing supercharger system on an engine already installed in an aircraft, if that's your intention, is reinventing the wheel, or a recipe for problems, or both.

Uh, no -- the idea would have been to have designed the aircraft from the start around the difference.

QuoteThe R-2800 was available in 1942 in 2-stage supercharged form, so let's use what is available.

Actually the F7F-1 used a single-stage, twin-speed supercharger -- which is why I proposed twin-stages.

QuoteThe R-2800-18 indeed have had hydrauilcal clutch for auxiliary stage, thing being that speed ratios were pre-set, there was no variation of speed like it was the case with Allison take on the same problem.

Oh... okay

QuoteSo unless we have the F7F with at least 700 gals internally (two engines to feed...), plus 600 gals externally, it wont be much of a long range fighter, at least not under USAF conditions, that were demanding much greater cruise speed and altitude than USN conditions. Perhaps it would be a good idea to get rid of .50s and their ammo, cram more fuel there.

I had considered the possibility of removing some guns...

Not sure what is the issue - I know that Tigercat used 1-stage supercharged engines, and I agree with proposal to have 2-stage engines if we want the new variant to be great performer also at 25000-30000 ft. Just pointing out that sticking another stage and intercooler on any engine installed is non-starter :)

everybody

I'm curious when the US Army procured the XP-50?


tomo pauk

QuoteNot sure what is the issue

A communications gulf: I explained the issue would have -- for WHIF purposes -- to have had the aircraft fitted with a twin-stage engine from the outset, not modifying an extant engine installed.

QuoteI agree with proposal to have 2-stage engines if we want the new variant to be great performer also at 25000-30000 ft.

Which is basically the goal

Quote from: KJ_Lesnick on February 01, 2016, 12:48:30 PM
everybody

I'm curious when the US Army procured the XP-50?

I found the answer to this very easily on the internet --- try looking yourself for a change --

Quote from: tomo pauk on February 01, 2016, 01:37:38 AM
Not sure what is the issue -

Don't worry, she'll invent one ---

I know this is an old post, but it's still something that interests me: I'm kind of interested that the Grumman 46 started before the USAAF procured the XP-50.  I'm curious if this was enough to throw a monkey-wrench into the idea?

Regardless, I find it fascinating that the hydraulic clutching used by the R-2800 didn't seem to mean the same thing as the V-1710's: I'm surprised they wouldn't jump on the possibility of variable-speed off the bat.

I'm also curious how a turbo would have worked if the turbine was pointed straight aft with the exhaust heading through it like on the P-67 Bat.  It would provide the benefits of a turbo and thrust...

Recce carrier borne USMC Grumman Tigercat.

(https://hosting.photobucket.com/images/j340/ysi_maniac/TigerCat_Avenger.jpg?width=1920&height=1080&fit=bounds) (https://app.photobucket.com/u/ysi_maniac/a/caec78e4-057f-4fe9-82f4-083a43455765/p/42a814eb-4d73-456e-acce-c5d3fe1ef3d4)

Intriguing mix of parts  :thumbsup:

I like the look of it, even though I have doubts concerning the landing gear, esp. the front wheel well and the observer's station. The arrester hook appears quite short, too? Looks like a cool (and massive!) 1945 design, though.  :thumbsup:

(https://live.staticflickr.com/7893/32582035957_7434ab60ca_o.jpg)

(https://live.staticflickr.com/7852/47471774612_3f859b2ef4_o.jpg)

Paired engines and T tail  :thumbsup: :thumbsup:

Secretprojects has a fuzzy pic that seems to have an early F7F or XP-65 mockup:
https://www.secretprojects.co.uk/threads/grumman-f7f-very-early-model-pics.7404/#post-619266

Grumman Parade f7f or xp65 mockup.jpg
 
I like the more bubble shaped canopy.

Quote from: perttime on September 02, 2023, 10:57:27 PMSecretprojects has a fuzzy pic that seems to have an early F7F or XP-65 mockup:
https://www.secretprojects.co.uk/threads/grumman-f7f-very-early-model-pics.7404/#post-619266

Grumman Parade f7f or xp65 mockup.jpg
 
I like the more bubble shaped canopy.

It's possibly before they raised the decking behind the pilot to accommodate a reserve fuel tank.
This proved serendipitous when they decided to make a two-seat nightfighter, the radar operator
position went in where the tank had been installed.

And avoided an Hornet-style pimple...