Aircraft engines. Swapping and upgrading.

[Mossie]

150hp is a good difference but not huge, it may well have been made up in development.  The Peregrine & Merlin shared some feature as they were developed around the same time, as I mentioned, it was intended to have a family of engines, they both would have existed even if the Merlin had been entirely dropped, which I think would have been unlikely.

Rolls Royce & the Air Ministry initially favoured the Peregrine due to it's light weight & more streamlined profile, the Merlin was intended to 'fill the gap' between the Peregrine & Vulture.  The Rolls Royce staff would have little idea initially just how far the Merlin could have been pushed. If the Peregrine had been reliable, it may well have taken precedence, due to it's higher power to weight ratio & streamlining.  On the surface, with all the information at the time, it seemed the better option before it was realised the Pergrine was unrealiable.

[elmayerle]

I don't know about the Peregrine, I don't think it had the development potential, RR would build a few engines and then see which one was easier to develop.  The Merlin in it's first redentation, put out 980+ hp, and by the end of WW.II had been developed to put out 2040 hp, that's in 6 or 7 years.  Really remarkable considering that the bore and stroke stayed the same all through it's development.

Actually, from what I've been able to find from reading, the Peregrine was the ultimate development of the Kestrel and, for the most part, the basic engine had been pushed as far as that displacement could go.

Relative to the Merlin, I've seen it documented that in 1938, the Allison V1710 actually had more power, but Allison had far fewer people to work on improving their engines than RR did.  It does make you wonder what a V1710 would've done with two-stage supercharging like the Merlin's.

[RLBH]

To my mind, the Peregrine MIGHT have been pushed to 1,230 horsepower or so, if the same level of technology as the Merlin 61 was utilised. Would probably help the Whirlwind, but I don't see it being used for much else.

Of course, the Avro Manchester and Hawker Tornado both flew with the Vulture. Tornado and Typhoon, of course, were essentially the same aircraft, and the Manchester turned into the Lancaster. My favourite Vulture aircraft is the Blackburn B.20, though...

[Archibald]

As I posted in the Whirlwind thread, dimensionally the Peregrine and Merlin are actually very close, displacement and weight are the big difference:

Peregrine:
Length 73.6"; width 27.1"; height 41.0"; weight 1,140 lbs.
Displacement 1,296 cu in.

Merlin (single-speed supercharger):
Length 69"; width 29.8"; height 41.2"; weight 1,375 lbs.
Displacement 1,637 cu in.

Merlin (two-speed supercharger):
Length 71"; width 29.8"; height 43.0"; weight 1,450 lbs.
Displacement 1,637 cu in.


Cheers, Jon

As a frenchman my thinking are in kilograms, not Ibs    

1 Ib = 0.45 kg
10 Ib = 4.5 kg
200 Ib = 90 kg

So exchanging Peregrine for Merlin (single-speed supercharger) would have added roughly 200 kg (of engine) to the Whirlwind. But you also have to add some kilograms of structural mods (how many ? 200 to 400 kg ?)

This would add roughly a ton (2100 Ib) to the Wirlwind... is this very much ?    Would it waste the aircraft ?

[jcf]

As I posted in the Whirlwind thread, dimensionally the Peregrine and Merlin are actually very close, displacement and weight are the big difference:

Peregrine:
Length 73.6"; width 27.1"; height 41.0"; weight 1,140 lbs.
Displacement 1,296 cu in.

Merlin (single-speed supercharger):
Length 69"; width 29.8"; height 41.2"; weight 1,375 lbs.
Displacement 1,637 cu in.

Merlin (two-speed supercharger):
Length 71"; width 29.8"; height 43.0"; weight 1,450 lbs.
Displacement 1,637 cu in.


Cheers, Jon

As a frenchman my thinking are in kilograms, not Ibs    

1 Ib = 0.45 kg
10 Ib = 4.5 kg
200 Ib = 90 kg

So exchanging Peregrine for Merlin (single-speed supercharger) would have added roughly 200 kg (of engine) to the Whirlwind. But you also have to add some kilograms of structural mods (how many ? 200 to 400 kg ?)

This would add roughly a ton (2100 Ib) to the Wirlwind... is this very much ?    Would it waste the aircraft ?

Hi Archie,
switching to the Merlin would not add as much weight as you have posited.
The center wing section was built integrally with the forward fuselage and the arrangement of spars and extrusions made a for a strong structure. The engine mounts bolted to the forward spar so any strengthening would likely have been local. The increased weight would have changed the CG of the aircraft, the best solution would be a lengthening of the rear fuselage.

Petter was working on a Whirlwind II, so a 'Whiff' Whirlie II redesigned for Merlins would not be out of the question.

As to the supposed streamlining advantages of the only marginally smaller Peregrine, the DH Hornet had sleeker nacelles than the Whirlwind yet used a dimensionally larger engine.

Cheers, Jon

[kitnut617]

According to the book 'Westland Aircraft', the rear fuselage of a Whirlwind from the trailing edge of the wing backwards, was made using magnesium (at the time a non-strategic material), especially all the skin.  Change this to aluminum and as Jon says increase the lenght a bit and you can cover whatever the weight increase forward.  

I've always thought that this aircraft was under utilitized, even for those times it could have been used to strafe airfields that were close to the shore and add a couple of drop tanks even further afield, forcing these airfields location further away and decreasing what the Luftwaffe could do.

Robert

Edit:  One square foot of 11ga aluminum = 1.279 lbs
        One square foot of 11ga magnesium = .838 lbs

[Archibald]

As I posted in the Whirlwind thread, dimensionally the Peregrine and Merlin are actually very close, displacement and weight are the big difference:

Peregrine:
Length 73.6"; width 27.1"; height 41.0"; weight 1,140 lbs.
Displacement 1,296 cu in.

Merlin (single-speed supercharger):
Length 69"; width 29.8"; height 41.2"; weight 1,375 lbs.
Displacement 1,637 cu in.

Merlin (two-speed supercharger):
Length 71"; width 29.8"; height 43.0"; weight 1,450 lbs.
Displacement 1,637 cu in.


Cheers, Jon

As a frenchman my thinking are in kilograms, not Ibs    

1 Ib = 0.45 kg
10 Ib = 4.5 kg
200 Ib = 90 kg

So exchanging Peregrine for Merlin (single-speed supercharger) would have added roughly 200 kg (of engine) to the Whirlwind. But you also have to add some kilograms of structural mods (how many ? 200 to 400 kg ?)

This would add roughly a ton (2100 Ib) to the Wirlwind... is this very much ?    Would it waste the aircraft ?

Hi Archie,
switching to the Merlin would not add as much weight as you have posited.
The center wing section was built integrally with the forward fuselage and the arrangement of spars and extrusions made a for a strong structure. The engine mounts bolted to the forward spar so any strengthening would likely have been local. The increased weight would have changed the CG of the aircraft, the best solution would be a lengthening of the rear fuselage.

Petter was working on a Whirlwind II, so a 'Whiff' Whirlie II redesigned for Merlins would not be out of the question.

As to the supposed streamlining advantages of the only marginally smaller Peregrine, the DH Hornet had sleeker nacelles than the Whirlwind yet used a dimensionally larger engine.

Cheers, Jon

Ok, that's quite a good news    

Is there any mention of this Whirlwind II in Tony Buttler "british secret projects 1935-1950" ?    

[Mossie]

the rear fuselage of a Whirlwind from the trailing edge of the wing backwards, was made using magnesium (at the time a non-strategic material), especially all the skin.

I didn't know this, thanks for the info Robert.  I know magnesium is harder to ignite in ingot or sheet form, but I still wouldn't like have a fire in the Whirlwind. I guess that's part of the reason it was only used aft of the wing, maybe structural strength too.

Okay, so we've talked about the Peregrine, what about the Vulture?  Maybe not a huge amount of development in that either, but it still might provide a lot of power from an in-line early in the war had it been reliable.  Faster bombers, or more likely, heavier bomb loads earlier?

[NARSES2]

the rear fuselage of a Whirlwind from the trailing edge of the wing backwards, was made using magnesium (at the time a non-strategic material), especially all the skin.

I didn't know this, thanks for the info Robert.  I know magnesium is harder to ignite in ingot or sheet form, but I still wouldn't like have a fire in the Whirlwind.

The XP-56 Black Bullet was built from welded Magnesium and had to be constructed in "sand-boxes" because the thing caught fire so often that they simply threw sand over it  

I knew the Whirlwind used Magnesium Alloy but some of those are a lot less combustable then Magnesium in it's pure/nearly pure forms.

Reminds me of some of the tales I@ve heard of people trying to use Lithium Alloys in aircraft.

Chris

[kitnut617]

I knew the Whirlwind used Magnesium Alloy but some of those are a lot less combustable then Magnesium in it's pure/nearly pure forms.
Chris

Yeah, I meant Magnesium Alloy.

[NARSES2]

Thought you did, just wanted to check I hadn't miss-read something

[Mossie]

Apparently the Vulture was fine - or at least less problematical - in the Tornado.  It was when it was used for heavy loads in the Manchester (and likely the Blackburn B20 too) that it as causing the problems.

I'd forgotten about the Tornado & hadn't really thought about the Vulture's use in a fighter (single engined at least).  So assuming that the Vulture problems were ironed out at least for lighter aircraft, we could have some pretty grunty fighters before the Griffon & Sabre came along.

So what could we put it on?  Mossies maybe or are they too heavy?  Having a mind block right now, can't think of anything else other than the Hawker family!  Would definately look a little different on a fighter with those four exhausts.

[kitnut617]

So what could we put it on?  Mossies maybe or are they too heavy?  Having a mind block right now, can't think of anything else other than the Hawker family!  Would definately look a little different on a fighter with those four exhausts.

I would say Fulmar, Firefly, Tempest, any of the bigger fighters,  maybe the Mossie and Beaufighter, a Brigand maybe! Barracuda, Spearfish, how about a re-engined Avenger

[jcf]

So I guess we're positing a timeline where the Allies are as blinded by technical 'possibilities' as the Germans, and instead of rationalized production of incrementally improved and available technology, go wandering down the garden path trying to perfect flawed or gee whiz designs?

'Twould make for a long war and create an even greater war debt.

Cheers, Jon

[Mossie]

So what could we put it on?  Mossies maybe or are they too heavy?  Having a mind block right now, can't think of anything else other than the Hawker family!  Would definately look a little different on a fighter with those four exhausts.

I would say Fulmar, Firefly, Tempest, any of the bigger fighters,  maybe the Mossie and Beaufighter, a Brigand maybe! Barracuda, Spearfish, how about a re-engined Avenger

Barracuda! Do you think that would make the beast even uglier???  Surely not?!?!?

So I guess we're positing a timeline where the Allies are as blinded by technical 'possibilities' as the Germans, and instead of rationalized production of incrementally improved and available technology, go wandering down the garden path trying to perfect flawed or gee whiz designs?

'Twould make for a long war and create an even greater war debt.

So are you saying Jon, had the Pergrine & Vulture been developed more sucessfully, they would never have been used operationaly in any aircraft other than happened in this timeline?  British wartime procurement didn't always seem to be led by pure logic.  The Griffon & Sabre had their own difficulities, it's not inconcievable that they may have been cancelled too, types were delayed because of it.  Who's to say had the Vulture been available & ready, those would have been continued with?  Saying the development of two engines by one company would lead to a longer war is taking a big stretch!