Harrier and Sea Harrier

[PR19_Kit]

I don't see why the gearbox to split the dual fan drive wouldn't work. After all the F-135 in the F-35B not only has a socking great gearbox to switch the lift fan drive through 90 deg. but a clutch as WELL!

[Old Wombat]

So, will the manual versions be synchro-mesh or crunch-box?





Coat! ... Hat! ... Whoosh!

[sandiego89]

So, will the manual versions be synchro-mesh or crunch-box?





Coat! ... Hat! ... Whoosh!

Perhaps use the clutch on my Acura- if it could survive teaching my teenage daughter how to drive a manual (increasingly rare in the USA) it could surely withstand the mere 18,000 lbs of force on the F-35B lift fan 

[rickshaw]

I assume these lift fans would be in tandem, rather than side-by-side?   Would still make for some interesting plumbing.  Also the use of two gear boxes to drive them would increase likelihood of a failure.  However, it has potential.  I'd still prefer one, large fan.  It would require a broad flat fuselage but that could lead to advantages in the form of either internal weapons bays (for stealth) or forward lift, from a suitably shaped fuselage, thereby reducing the wing area and therefore drag.

I've been looking at commercial turbofan sizes and the IAE V2500 is clearly the winner here, with up to 35k lbs thrust in it's most powerful version, with a 1.6m fan diameter, which is larger than the 1.2 of Pegasus but not exorbitantly so.

Nope, you've misunderstood me: they're not "lift fans", they're turbofan fans with vectoring nozzles behind them. Put it this way: what you'd really like is an oval fan, thats wider than it is high, but that's technically impossible, so the next best thing is a pair of smaller circular fans side-by-side.

I get it Weaver and like the idea, and have thought about that also- what Weaver is proposing is the first stage compressor- the fan you see looking at the front of a jet engine, actually being two first stage compressors coming off a singe engine core.  So two smaller first stage compressors, merging into a single core.  The majority of the cold bypass air would then go to both sides of the core where it could be thrust vectored, with some air from each compressor going to the common core- feeding the hot section with air.  Compressor aft of the hot section drives a shaft that goes back forward to spin the compressor(s). Would need a differential coming of the shaft to split the power to the two compressors. 

Hot section could also be diverted- and have an afterburner/reheat for convetional mode.  
This allows for a smaller front section, and a layout compatiable with an intake on each side of the fuselage (Yak-141 style)

A very crude keyboard mockup, when viewed from above.  The double row XX represents a port and starboard first stage compressors.  

                 _________________________________
                         XX     [                                         [    ]
 Right intake       XX     [  downward                        [  second nozzle for
                         XX     [  nozzle/flap                       [  top half of cold air
                       <XX>   [                                        [    ]
                         XX     [                                         [   ]
 ______             XX---------------------------------------------------------
            \___      XX            X    X                                                X     Hot nozzle/
 Cockpit        \ -------------- X –-X--common shaft-- Hot section     X     Afterburner>>>>    tail
              ___/    XX            X    X                                                X
 ______/            XX---------------------------------------------------------
                         XX     [                                         [    ]
 Left t intake    <XX>   [  downward                        [  second nozzle for
                         XX     [  nozzle/flap                       [  top half of cold air
                         XX     [                                        [    ]
                         XX     [                                         [   ]
             ___________________________________  

An interesting idea.  What happens though if one fan seizes because of a gear box problem?  How do you handle the asymetrical loads or do you just accept, as the Russians did that if that happens you're just going to lose the aircraft and have the pilot automatically punch out as soon as it departs from controlled flight parameters?   I can also see problems with that hot core being used at the rear.  It's going to make vertical take off/landing difficult, rather as the P1154 found.   It is though, I admit a better idea than plenum chamber burning.

[PR19_Kit]

It'll be the same if the clutch or gearbox fails during vertical or short TO/L ops with the F-35B. The only command you need to remember is 'EJECT!' as the aircraft will surely pitch tail over nose VERY quickly, while at the same time descending like a brick....

[rickshaw]

It'll be the same if the clutch or gearbox fails during vertical or short TO/L ops with the F-35B. The only command you need to remember is 'EJECT!' as the aircraft will surely pitch tail over nose VERY quickly, while at the same time descending like a brick....

Depends I suspect where you are in the flight envelope.  With the F-35, there is a chance you could always swivel the rear duct backwards and build up air speed to get lift from the wings and execute a conventional landing?  With this proposed system you'd have to deal with asymmetrical side as well as fore-aft loads?

[McColm]

India was the only country that bought the Sea Harrier. Where they ever offered the Sea Harrier II?

[Weaver]

If I remember correctly, India were offered the SHAR FA.2, but they thought the Blue Vixen was too expensive, possibly because it had to be a modified version to take out the AMRAAM compatibility at the Americans' insistance . They eventually went with an Israeli radar upgrade that used the original nose profile.

[dy031101]

I once read an article on CVV.  A comparison chart pointed out that the modernised Midway class, while capable of catapulting and recovering F-14s, cannot support them because their hangars do not have the clearance (17.5') required to perform services on the Tomcats (landing gear drop-check and ejection seat removal are invoked as examples; CVV has 24' to accommodate such jobs).

I wonder what would be the hangar clearance required to service Harrier II.  Does anyone know?  Thanks in advance.

[Thorvic]

I once read an article on CVV.  A comparison chart pointed out that the modernised Midway class, while capable of catapulting and recovering F-14s, cannot support them because their hangars do not have the clearance (17.5') required to perform services on the Tomcats (landing gear drop-check and ejection seat removal are invoked as examples; CVV has 24' to accommodate such jobs).

I wonder what would be the hangar clearance required to service Harrier II.  Does anyone know?  Thanks in advance.

Harrier II would be OK, the Indian Navy used Sea Harriers on the Majestic Class Carrier Vikrant

[dy031101]

Harrier II would be OK, the Indian Navy used Sea Harriers on the Majestic Class Carrier Vikrant

What would be the minimum that can support the Harriers though?

I came across this (see Hornet class Strategic Sea Control Ship) and saw that the author divided the ship's airwing stowage into helicopters (Seakings or Seahawks) in the superstructure and Harriers below deck.

So here is what I'm wondering- how compact can a hangar get while servicing the Harriers is still doable, or am I looking at one of the helicopter hangars being used to service the Harriers as well?

[sandiego89]

Harrier II would be OK, the Indian Navy used Sea Harriers on the Majestic Class Carrier Vikrant

What would be the minimum that can support the Harriers though?

I came across this (see Hornet class Strategic Sea Control Ship) and saw that the author divided the ship's airwing stowage into helicopters (Seakings or Seahawks) in the superstructure and Harriers below deck.

So here is what I'm wondering- how compact can a hangar get while servicing the Harriers is still doable, or am I looking at one of the helicopter hangars being used to service the Harriers as well?

I can't get your link to work on my work computer, but it may depend on how you define minimum.  The Harrier/Sea Harrier could operate from a small ship like a cruiser or destroyer with a helo pad, and helo hanger, but really would provide zero practical utility.  This is due to VTOL requirement due to a helo sized flight pad- giving very little weight allowance for payload (fuel/weapons).

A Sea Control Ship is about the smallest size practical for a meanifull Harrier/Sea Harrier capable ship.  This is basically what the first Spanish carrier and the related Thai carriers turned out to be.  The hangers (and elevators) are large enough to carry around a half dozen harriers. You need enough hanger space to store and work on the aircraft.  I do not sea anything much smaller than that really being practical. You want at least @ 300 feet of deck run and a ski jump to allow takeoff with a usefull playload.  That drives ship size. 

Sea harriers had nose fold, harriers did not, neither had wing fold, so that gives you minimum span and length requirments for elevators and hangars.  A practical hanger size requirment would allow for an engine change at sea. Not an easy task for (sea)harrier, as it requires wing removal and engine removal from above.  This drives hanger ceiling height, at least for  a part of the hanger to likely around 20 feet minimum.     

[Weaver]

The Vikrant would have had a 17'6" height hanger IIRC.

The other limitation on Sea Harrier ops is the cost-effectiveness one that derives from the indivisibility of some of the support equipment. Some pieces of gear (expensive test rigs, for example) are issued on a one or two per squadron basis, but if those twelve aircraft are dispersed across 6 small ships, then each ship has to have ALL the gear, because if an aircraft goes u/s, it would be very difficult to move it to another ship for repair.

According to D.K. Brown in Rebuilding the Royal Navy, the studies they did established that the minimum cost-effective number of Sea Harriers on a ship was six, whatever it's handling arrangements.

[Captain Canada]

But this is whif world so any number would be fine. Same as hangar heights. If you were modding a ship to be a Harrier carrier then I'm sure you could modify decks as well, or have an area of specific height to work on them. Besides, they are nowhere near as large as an F-14.

I'm also thinking that the way they remove the wing to access the engine would ease maintenance. Not sure how long it takes to do so, but maybe a new generation of Harrier could address the removal.

[dy031101]

I can't get your link to work on my work computer, but it may depend on how you define minimum.

I know words alone won't help much, but the Shipbucket illustration specifies a what-if ship along the line of Strike Cruiser Mk.II:

Displacement at standard load was 19,810 tons, dimensions 202.7/24.1/7.8m Flight Deck 178.7/16.2m, four General Electric LM2500 gas turbines delivering 86,000hp to two shafts for a maximum speed of 30kts, range was 10500 miles. The armament comprised a single 5in, one 32-cell VLS for RIM-66C Standard SM-2MR SAM, two quadruple Harpoon and three Phalanx Mk 15. The air group comprised six AV-8 and six Seaking or nine Seahawk Three hangars in the superstructure could house six aircraft, the rest being carried in an aft below decks hangar. A full carrier radar fit was carried; SPY-1A 3-D, SPS-49, SPN-67, four SPG-62, one SPG-9, SQS-53, and SQR-19 (TACTAS) passive towed sonar.

In a follow up post it is said that there are three helicopter hangars (which I assumed to maybe have a higher clearance because of the Seakings) in the superstructure whereas the six Harriers are stored below deck.