Westland Whirlwind revisited

[Wild_Bill_Kelso]

And...AGAIN, it would be a LOT of effort. I keep telling you that it would be a lot of effort and you keep coming back and questioning whether it would be. Trust me...it would be a LOT of effort. You can't make a large change to something like the wing without there being a lot of knock-on consequences for other aspects of the design. IT IS A MAJOR CHANGE THAT WOULD DRIVE REDESIGN OF ALMOST ALL THE REST OF THE AIRFRAME.

The same can be said, I think, for putting a 70' wing on a 'similar airframe' plus two merlins, but they seem to have done that fairly quickly.

Aside from the Spitfire 21, off the top of my head, they increased the wing size of the B-26 rather quickly. F4F went from non-folding to folding wings pretty quickly. A6M was made with shorter wings for the A6M3 in time to participate on the war. The British version of the Corsair had smaller wings.

Wings were redesigned for the Ju 88 had it's wing span increased between the A-1 and A-4 and A-5 versions, and both the Ju 88 and the Pe 2 to strengthen them for dive bombing (in both cases rather hastily), and the Ju 88C also had enlarged wings.

And the Spitfire had wings which could be modified for high (extended) or low (cropped) altitude configurations

Aside from internal strengthening for dive bombing (which seems pretty substantial), in most cases this was just either lengthening or shortening the wings. So I know that is not as involved in terms of knock on effects and so forth as actually changing the shape of the wing. The first (pretty famous) example which comes to mind where a wing shape is substantially changed is the Tempest (originally Typhoon Mk II, interestingly enough), as distinct from it's 'cousin' the Typhoon. The Tempest had a fairly long development but the new wing seems to have been designed rather quickly. According to the Wiki, engineers were assigned to look into the NACA laminar flow wing in March 1940, they got a specification in March 1941 and the prototype flew in November 1941.

Subsequent delays were down to the various engines, not the wing so much as far as I can tell.

 

[buffnut453]

The same can be said, I think, for putting a 70' wing on a 'similar airframe' plus two merlins, but they seem to have done that fairly quickly.

Aside from the Spitfire 21, off the top of my head, they increased the wing size of the B-26 rather quickly. F4F went from non-folding to folding wings pretty quickly. A6M was made with shorter wings for the A6M3 in time to participate on the war. The British version of the Corsair had smaller wings.

Wings were redesigned for the Ju 88 had it's wing span increased between the A-1 and A-4 and A-5 versions, and both the Ju 88 and the Pe 2 to strengthen them for dive bombing (in both cases rather hastily), and the Ju 88C also had enlarged wings.

And the Spitfire had wings which could be modified for high (extended) or low (cropped) altitude configurations

Aside from internal strengthening for dive bombing (which seems pretty substantial), in most cases this was just either lengthening or shortening the wings. So I know that is not as involved in terms of knock on effects and so forth as actually changing the shape of the wing. The first (pretty famous) example which comes to mind where a wing shape is substantially changed is the Tempest (originally Typhoon Mk II, interestingly enough), as distinct from it's 'cousin' the Typhoon. The Tempest had a fairly long development but the new wing seems to have been designed rather quickly. According to the Wiki, engineers were assigned to look into the NACA laminar flow wing in March 1940, they got a specification in March 1941 and the prototype flew in November 1941.

Subsequent delays were down to the various engines, not the wing so much as far as I can tell.

I think part of the problem is you're using imprecise terminology to explain your points. In post #795 you used the term "not wide enough" then mentioned aspect ratio and showed a different airframe that had wings of apparently greater chord.

As you've noted, changing the wingspan doesn't have a big impact on other design factors providing the extended wing is sufficiently strong. It will add weight and change control response but it's not a major change, which is why it could be accomplished relatively easily.

Changing the chord of the wing has a BIG impact on other design factors. Here are a few examples:

• Let's take the existing wing and just increase the chord. Whoops...you've just changed the aerofoil section, which alters the amount of lift generated, and moves the centre of pressure...which likely means relocating the wing on the fuselage with a redesign of the fuselage centre section. The longer chord means the engines are relatively further forward which will change the CofG...which will require some balancing mechanism, probably to include extending the fuselage and installing larger tail surfaces.
• Let's keep the same aerofoil section but with a longer chord. Whoops...now the wing is thicker at the root so the existing mount into the fuselage won't work and needs to be modified, requiring an entire redesign of the fuselage centre section. The larger wing chord will still move the engines further forward so you still have all the other CofG and fuselage/tail changes.

For all its many variants, the Spitfire fuselage remained pretty similar throughout its life. Yes, it got larger tail feathers and there were some structural changes. However, the fuselage and the wing position/mount remained remarkably similar throughout most of the long design life of the type.

You keep bringing up the Tempest as the "Typhoon MkII" but the Tempest went through a host of redesign efforts, some of which were tied to different engines but some were changes for the same engine (e.g. moving the radiators from the nose to the wing root and back again). The Tempest wing was larger than that of the Typhoon...but the Tempest fuselage was also a foot longer than the Typhoon, which rather proves my point about knock-on consequences of wing redesign. There's no such thing as a free lunch. Despite the first prototype Tempest being rather similar to the Typhoon (at least in the fuselage and tail), later redesigns changed a lot more of the structure and shape.

 

[warbird51]

Some purely FICTIONAL versions drawn up years ago:

View attachment 711086
View attachment 711087

And some alternate users (and developments):

View attachment 711088

I love what you have done with the drawings!!! I am planning on building a 74" wingspan rc model and it gives me some ideas on a paint scheme!!!

If Westland would have enlarged the Whirlwind about 20% or so (like the P-39/P-63), then Merlin's would have worked. Keep the span the same, but enlarge the wing cord. So the roll rate would not be adversely affected. Of course, just keep Rolls Royce developing the Peregrine and fix the coolant/prop/ fuel issues and you would have a very improved aircraft.

 

[Shortround6]

Wings were redesigned for the Ju 88 had it's wing span increased between the A-1 and A-4 and A-5 versions, and both the Ju 88 and the Pe 2 to strengthen them for dive bombing (in both cases rather hastily), and the Ju 88C also had enlarged wings.

The longer wings on the JU-88 were developed for the A-4 but due to delays with the engines they started making the A-5s with the bigger wings and the engines from the A-1s.
The early Ju-88Cs had the short wings and the later Ju-88cs got the same longer wings (outer panels) as the A-4/5 got.
Not sure if there was any reinforcement of the innner wings but if not, all of the changes were outboard from the joint that started the Ailerons.

Note the Break in both the leading edge and the trailing edge and on the Ju-88s they just extended the wing tips using the same angles and extended the ailerons.
You can play a few games with exact center of lift but most of the change is pretty close to the center of wing as it was.

The Martin B-26 was similar, the leading edge stayed the same. The Trailing edge from about the engine nacelle outboard was changed and about an extra 3 feet was added to each side and the cord was increased a bit as the wing got further out.

Note the short span in the center of the drawing. No kink at all in the wing trailing edge, also the different ailerons and also note that they changed the flaps (added them outboard of the engine nacelles) to handle the higher speeds, increased weight. More changes than the Ju-88 had.

You can usually make a few parts thicker without changing to much else.
When you start changing airfoils or cords or number of spars things get complicated real quick. You are not adding a hinge point and local reinforcing, you are tossing most of the wing (all of it?) and the tooling and starting over. F4F with a folding wing flew about the same as the non folder ( a little heavier) and stall the same and you could make a large percentage of the wing parts using the same tooling.
Hawker Tempest didn't fly the same as a Typhoon (different stall for one thing) and you needed mostly new tooling to build the wing.

 

[special ed]

Some purely FICTIONAL versions drawn up years ago:

View attachment 711086
View attachment 711087

And some alternate users (and developments):

View attachment 711088

Actually, the one on floats seems very possible, especially with the high stabiliser.

 

[Glider]

And...AGAIN, it would be a LOT of effort. I keep telling you that it would be a lot of effort and you keep coming back and questioning whether it would be. Trust me...it would be a LOT of effort. You can't make a large change to something like the wing without there being a lot of knock-on consequences for other aspects of the design. IT IS A MAJOR CHANGE THAT WOULD DRIVE REDESIGN OF ALMOST ALL THE REST OF THE AIRFRAME.

If I can add one comment that supports this. We were taught when being trained as an artificer that weight grows incredibly.

As a rule of thumb, if you add a pound in empty weight to an aircraft and want to keep exactly the same performance in every way, it actually added 10 pounds to the weight.

 

[buffnut453]

If I can add one comment that supports this. We were taught when being trained as an artificer that weight grows incredibly.

As a rule of thumb, if you add a pound in empty weight to an aircraft and want to keep exactly the same performance in every way, it actually added 10 pounds to the weight.

Yep...the main spar in an aircraft's wing is not unlike the keel of a ship because it must bear all the weight of the aircraft and its cargo. Obviously, the main spar provides strength for the wings but it's also the mounting point for engines, guns, bombs, undercarriage, main fuel tanks etc. Change the position of the main spar and the entire aircraft structure will have to be modified.

The following photo and cutaway of the Whirlwind show how all the heavy items are tied into the main spar in some fashion:

Now compare with a photo of the Welkin. The first big change is that the Whirlwind has a low-mounted wing while the Welkin has a mid-set wing. Note how the general main spar position runs through the cockpit of the Welkin. Why? Because the Welkin had a heavy, pressurized cockpit that had to be adequately supported. In the Welkin, the cannon no longer protrude forward of the main spar, as is the case with the Whirlwind. Instead, they're carried in a bay beneath the fuselage...which is connected to the main spar.

As I've said multiple times, there's no free lunch with aircraft design. Changing one variable will result in many knock-on consequences. An airframe with growth potential is better able to absorb those consequences without major redesign. Aircraft without growth potential become obsolete faster and must be replaced by entirely new designs.

 

[Wild_Bill_Kelso]

View attachment 711105
The longer wings on the JU-88 were developed for the A-4 but due to delays with the engines they started making the A-5s with the bigger wings and the engines from the A-1s.
The early Ju-88Cs had the short wings and the later Ju-88cs got the same longer wings (outer panels) as the A-4/5 got.
Not sure if there was any reinforcement of the innner wings but if not, all of the changes were outboard from the joint that started the Ailerons.

View attachment 711106
Note the Break in both the leading edge and the trailing edge and on the Ju-88s they just extended the wing tips using the same angles and extended the ailerons.
You can play a few games with exact center of lift but most of the change is pretty close to the center of wing as it was.

The Martin B-26 was similar, the leading edge stayed the same. The Trailing edge from about the engine nacelle outboard was changed and about an extra 3 feet was added to each side and the cord was increased a bit as the wing got further out.
View attachment 711107
Note the short span in the center of the drawing. No kink at all in the wing trailing edge, also the different ailerons and also note that they changed the flaps (added them outboard of the engine nacelles) to handle the higher speeds, increased weight. More changes than the Ju-88 had.

You can usually make a few parts thicker without changing to much else.
When you start changing airfoils or cords or number of spars things get complicated real quick. You are not adding a hinge point and local reinforcing, you are tossing most of the wing (all of it?) and the tooling and starting over. F4F with a folding wing flew about the same as the non folder ( a little heavier) and stall the same and you could make a large percentage of the wing parts using the same tooling.
Hawker Tempest didn't fly the same as a Typhoon (different stall for one thing) and you needed mostly new tooling to build the wing.

What about when they strengthened wings for dive bombing? that sounds like it would be pretty involved

 

[buffnut453]

What about when they strengthened wings for dive bombing? that sounds like it would be pretty involved

Not necessarily. You can add a lot of strength to the wing by using slightly thicker-gauge sheeting for the wing surface. Internal strengthening might take the form of reinforcement plates applied at points of weakness and/or additional cross-bracing to provide greater rigidity. None of those things are hard and, since they're close to the CofG and CofP, they don't have many knock-on consequences (except to the overall airframe weight, of course).

 

[MiTasol]

Rule one is KISS

I would recommend we go back to Petters proposed solution as that is by far the simplest. Fit Merlins with short four blade props and move assorted heavy components like batteries and radios rearward.

Add to that better radiators with pilot control of the radiator shutters, delete the outboard slats and fit more fuel outboard and some behind the cockpit.

End result is a basically prove airframe with lots more power and probably a significant improvement in climb and altitude and less improvement in speed

 

[wuzak]

Rule one is KISS

I would recommend we go back to Petters proposed solution as that is by far the simplest. Fit Merlins with short four blade props and move assorted heavy components like batteries and radios rearward.

Add to that better radiators with pilot control of the radiator shutters, delete the outboard slats and fit more fuel outboard and some behind the cockpit.

End result is a basically prove airframe with lots more power and probably a significant improvement in climb and altitude and less improvement in speed

If you use the power egg that was used on the Beaufighter and Lancaster you could add fuel to the inner wings as well.

 

[Shortround6]

If you use the power egg that was used on the Beaufighter and Lancaster you could add fuel to the inner wings as well.

Except now you have hundreds of pounds more weight (per engine) well in front of the center of gravity.

You might as well swap the Peregrine engines for Hercules engines, or buy American and stick Wright R-2600s on it

 

[buffnut453]

The Merlin is 15.1 ins longer than the Peregrine, and 3.7 ins wider...and 500 lb heavier. I struggle with the concept of moving enough weight aft to compensate for an additional 1000 lb or more ahead of the CofG. Petter was a brilliant engineer but it would be interesting to see how mature the Merlin Whirlwind concept was in reality.

Is suspect the real death-knell was economic. The Whirlwind consumed a lot more aluminium than a Spitfire (according to Wiki, three times more) and, of course, used up twice the number of engines without any promise of significant performance benefit over the Spit in terms of firepower or range.

 

[wuzak]

Except now you have hundreds of pounds more weight (per engine) well in front of the center of gravity.

You might as well swap the Peregrine engines for Hercules engines, or buy American and stick Wright R-2600s on it

But you have to redo the structure and weight balance to fit the Merlins anyway, so the extra weight will be compensated for in that process.

 

[don4331]

The same can be said, I think, for putting a 70' wing on a 'similar airframe' plus two merlins, but they seem to have done that fairly quickly.

Aside from the Spitfire 21, off the top of my head, they increased the wing size of the B-26 rather quickly. F4F went from non-folding to folding wings pretty quickly. A6M was made with shorter wings for the A6M3 in time to participate on the war. The British version of the Corsair had smaller wings.

Wings were redesigned for the Ju 88 had it's wing span increased between the A-1 and A-4 and A-5 versions, and both the Ju 88 and the Pe 2 to strengthen them for dive bombing (in both cases rather hastily), and the Ju 88C also had enlarged wings.

And the Spitfire had wings which could be modified for high (extended) or low (cropped) altitude configurations

Aside from internal strengthening for dive bombing (which seems pretty substantial), in most cases this was just either lengthening or shortening the wings. So I know that is not as involved in terms of knock on effects and so forth as actually changing the shape of the wing. The first (pretty famous) example which comes to mind where a wing shape is substantially changed is the Tempest (originally Typhoon Mk II, interestingly enough), as distinct from it's 'cousin' the Typhoon. The Tempest had a fairly long development but the new wing seems to have been designed rather quickly. According to the Wiki, engineers were assigned to look into the NACA laminar flow wing in March 1940, they got a specification in March 1941 and the prototype flew in November 1941.

Subsequent delays were down to the various engines, not the wing so much as far as I can tell.

You missed a couple dates for Tempest: Laminar flow investigation - March '40, Specification March '41, Contract Nov '41, 1st flight Sept '42, 1st production Jun '43, Introduction to service Jan '44. Almost 48 months from investigation to in service.

Dates for Welkin are almost same: Requirement F.4/40 March '40, Approval to Design Jan '41,1st flight Nov '42, 1st production approximately Oct '43, Introduction to service May '44. 52 months from requirement to in service.

One of the items Petters said he learned from Whirlwind was the delay from 1st flight of prototype to in service - 18 months.

None of us are saying that Westland could build a Merlin powered twin, just the amount of change => time of delay, would it still be front line.

You need to keep Whirlwind (Mk.II)/Peregrine(Mk.III) production in tact for that length of time (Jan 42 to June '43) it takes for Whirlkin to come on line. But will it be better than Typhoon/Tempest?

Aside: 8" circular radiator has frontal area of ~50 in^2; x3 = 150 in^2; rectangular radiator of 8 x 24 has 192 in^2, almost exactly the 25% increase needed for Merlin (and rectangular radiators are more efficient?)

 

[MiTasol]

Except now you have hundreds of pounds more weight (per engine) well in front of the center of gravity.

You might as well swap the Peregrine engines for Hercules engines, or buy American and stick Wright R-2600s on it

I would suggest R-1830s as the weight increase is not great and would produce a much smaller moment arm on the cg and they had them in the Beauforts and assorted other aircraft so the maintenance experience was there

 

[don4331]

The Merlin is 15.1 ins longer than the Peregrine, and 3.7 ins wider...and 500 lb heavier. I struggle with the concept of moving enough weight aft to compensate for an additional 1000 lb or more ahead of the CofG. Petter was a brilliant engineer but it would be interesting to see how mature the Merlin Whirlwind concept was in reality.

Is suspect the real death-knell was economic. The Whirlwind consumed a lot more aluminium than a Spitfire (according to Wiki, three times more) and, of course, used up twice the number of engines without any promise of significant performance benefit over the Spit in terms of firepower or range.

Wasn't Petter just planning to implement Merlin XX? For which have had lengths more/less equal at 73.6" for Peregine Mk.1 vs 71" for Merlin Mk XX, height of 41" for both and 27.1 vs 29.8, so 2.7" width, (2 stage Merlins are 15" longer, but he not planning Merlin 60 series at this point). Bare engine weight 1,140 vs. 1,450 lbs = 300lbs * 2 is still a lot.

Why do we keep comparing Whirlwind to Spitfire - the cannon armed fighter is the Typhoon and 2 Peregrines probably comes off better than a single Napier Sabre. RR could have driven nail in Napier's coffin by promoting Whirlwind over Typhoon - but that might not be popular with Hawkers...

 

[Shortround6]

I would note that Westland was in a bit of trouble as a company.

The Lysander was designed to be what the RAF and Army said they wanted. It turned out NOT to be what was needed. But in the rush to build up British forces in 1939/40 it often took priority over the Whirlwind.
RR decided the Peregrine had little or no future. No real fault of Westland. Jumo had given up on the 210 back in 1938 and P & W gave up on the R-1535 on the late 30s or by 1940. They completed contracts but R & D went to the R-1830 and R-2800 (P & W killed the R-2180 at about the same time).
For some reason a few people had it in for Westland, some rather exaggerated claims for maintenance times were being passed around.
And the comparison to the Spitfire turns out not be quite factual with hindsight. They thought at the time they could put 4 Hispano guns in the Spitfire so the Whirlwind didn't offer anything. Turns out it took several years for 4 cannon Spitfires to show up, aside from a small batch and they needed/wanted Griffon engines to do it.

But going back to the offer for Westland to make Merlin powered Whirlwinds, Lysander production was being cut way back, The Whirlwind was canceled unless they got a miracle. The were working on the Welkin with no guarantee that they would lead to production, contract for the two prototypes was placed Jan 1941. Westland was being reduced to satellite factory for Supermarine/Vickers. They did get a contract for the Welkin but not in numbers and the last fixed wing aircraft that Westland built was the Wyvern a pretty aircraft but not a success.

Petter had worked on a twin jet engine aircraft in 1944 but went on a several week absence (6 weeks?) and effort switched to the Wyvern in his absence. The resulting aftermath lead to Petter resigning and taking a lot the initial bomber calculations with him and he wound up at English Electric.

What was Westland (Petter) promising to keep from becoming a Supermarine assembly shop.

 

[wuzak]

RR decided the Peregrine had little or no future.

Rolls-Royce had to prioritise.

They cut their engine development programs from 5 or 6 down to 2 - the Merlin and Griffon.

And even work on the Griffon was reduced during the BoB.

the last fixed wing aircraft that Westland built was the Wyvern a pretty aircraft but not a success.

Do you really think the Wyvern was pretty?

 

[don4331]

Wasn't it Air Ministry that initially cancelled the Peregrine? Only to request RR resume for Whirlwind to be long range PR aircraft (early PR Mosquito. Then the DH propellers rob it of altitude performance.

Add outer wing and fuselage fuel tanks (interconnected with existing tanks) with Rotol propellers and Whirlwind is long range PR airplane when RAF wants every Hurricane & Spitfire for Fighter Command. Gives us critical role that keeps Whirlwind and Peregrine rolling.

RR's problem was every engine: Peregrine, Merlin, Griffon and Vulture needed a complete redesign to handle power that was being developed with 100 octane.
Griffon I was easiest to start over as no production tooling existed yet. Merlin was critical all over the place. Loss of the Vulture really hurts RR later in war/immediate post war - yes they develop Eagle, but a little late.

I think Wyvern is pretty airplane too. Pretty lucky too seeing RR canceled planned engines both piston and turbine.