Westland Whirlwind revisited
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Shortround6
Major General
The Peregrine has a frontal area of 5 sq ft vs the Perseus frontal area of 14.7 sq ft.
One source claims the Peregrine was 27.1 in wide. Granted the V -12 cowling cannot follow the shape of the engine as closely as the cowling of a radial.
The Whirlwind put the radiators inside the wing meaning there was no increase in frontal area of the aircraft itself. There is the drag of the air going through the duct and the radiator cores. But then you have the drag of the cooling air going through the radial cowling.
Unless you can come up with a cowling that is the equal or better than the one used on the FW 190 you are pretty much stuck with a rather high drag cowling.
9 cylinder radials being worst engines in the power to frontal area sweepstakes. This was part of the rational for the Taurus. a 25.4 liter engine of 46.2in diameter/11.7 sq ft frontal area vrs the 24.9 liter Perseus.
The other part/s of the rational was the higher rpm and that smaller cylinders are easier to cool. the last was not proved by the Taurus. The chronic cooling problems seem to be solved, in part, by using the engine at low altitudes in thick/dense air that gave better cooling.
The Perseus was supposed to be about 0.2 in smaller in diameter than a P & W R-2800 so yes, I will call it a large engine in size/frontal area.
Shortround6
Major General
Perseus engine on a Botha.
My apologies if this was mentioned earlier, but didn't Westland essentially upgrade the Whirlwind to become the Welkin? Other than the design for very high altitude combat you have the redesign for RR Merlin's, the guns are reconfigured for more ammo and service, and you have more fuel. It's unfortunate that the need disappeared before it could contribute to the war.
Shortround6
Major General
Upgrade,
develop from
adaptation
simple words for plane that added 25ft of wing span, 210 sq ft of wing area, over 9 ft of length and and weighed empty (no guns/equipment) what the Whirlwind did loaded with a pair of bombs under the wings. When loaded it was 74% heavier.
I would guess that there was darn little left of the Whirlwind except for the general shape and even that took a a rather hard squint.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
However, Allison powered aircraft were in their element at lower altitudes.
The Allison P-51 had other problems, apparently an issue with the Ailerons
Actually, I think this is a really good point. The Welkin was a far more radical redesign than I was suggesting, with a 70' long, completely redesigned wing and a pressurized cockpit (requiring an extra supercharger) but it does give some idea what could be done. And it did for example put the gun pod in the center which had the added benefit of hiding the muzzle flash better.
It kind of makes me rethink the possibility of using a Merlin or an Allison actually. Though I still have faith in the Peregrin.
Welkin was a major project which took a while to sort out, but something about halfway as ambitious, or maybe a quarter, (as I think an incrementally improved Whirlwind would be) clearly was feasible. Probably a Whirlwind variant with two stage or at least two speed merlin's was feasible too.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Interesting...
Was it the NA-73/NA-83 (Mustang I) or NA-91 (Mustang Ia)?
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The NA-91 (Mustang Mk.Ia/A-36) didn't seem to have that issue in USAAF service...
True, eventually, but Westlands originally told the Air Ministry that they would include many Whirlwind parts in what was to become the Welkin. Petter would promise just about anything in pursuit of a contract.
The company wrote that "We shall probably be able to use the Whirlwind outer wings, slots, ailerons, rear fuselage and tail unit with a number of the detail parts particularly those in the wing spar boom."
I've seen a drawing of an intermediate proposal that looks more like the Whirlwind than the Welkin, but I can't find it, despite knowing it is on this computer!
The best twin fighter the British might have developed was the Supermarine Type 313, which was the original Air Ministry favourite to F.37/35 and it too had its cannon armament mounted in the nose. It was cancelled for good reasons. It was designed around the Goshawk B, but given the close and longstanding relationship between Rolls-Royce and Supermarine, something Westlands did not have, I would be very surprised if it could not eventually have used the Merlin. That is a realistic 'what if'.
Yes they did. We had a long discussion about this in another thread. All of the Allison engine mustang variants had a comparatively poor air-to-air combat record despiite a substantial speed advantage over all the other Allied types. IIRC there was only one US pilot who made Ace flying the Allison engined Mustang despite their extensive use in both the MTO and CBI.
Somebody posted an article which explained the issue, was the aileron's were either too tight or too small I can't remember which. It affected the roll rate. This was fixed in the P-51B.
I'll try to find the article later today and link it.
Greetings Shortround6,
I suggested we consider the Welkin as an example of what the evolution of the Whirlwind with better engines would begin to look like. The 45k service ceiling requirement really governed a number of design developments like the wing length. Other design changes like the fuselage length are probably a combination of counterbalancing the weight of the engines and better control at altitude. For comparison I built up this quick study comparing the size of the Whirlwind, Hornet, and Welkin. I then overlaid the Welkin and Hornet nacelles on the Whirlwind using the spar line for reference. It gives as idea of the impact the Merlin or similar sized engine would have had on the design. At the very least, reengineering the Whirlwind with Merlins would require a longer body for counterbalance and a larger wing. Dimensionally, it would begin to look a lot like the Hornet or a short wing Welkin.
Note: all images have been properly scaled for accurate reference.
Admiral Beez
Major
This is why....
The nitpicker or contrarian does nothing but troll discussion forums for their perceived " gotcha moment", where they can tell us why something couldn't, wouldn't or shouldn't have occurred. It's a sad existence I imagine, sitting in a dark basement scouring the web for nits to pick.
Shortround6
Major General
Thank you for the scaled artwork.
They really put into perspective the differences between the aircraft and the problems with trying to modify the Whirlwind to equal many other twin engine aircraft, it really was a small airplane for a twin.
The three words/sets,
Upgrade,
develop from
adaptation
were each from a different account of the Welkin and in my opinion, seriously undervalue the amount of work needed to go from the Whirlwind to the Welkin and make it seem a bit too direct. Words/phrases like that are often used in accounts of aircraft (F6F was a development of the F4F?) when reality may have been a lot harsher. Most companies did keep sort of a family resemblance but that does not mean one aircraft was really developed from an early one except in a very general sense, like "we have used a vertical fin and rudder of this general shape on several aircraft and had no real problems, lets just scale it up or down to suit the new airframe and see how it works, now on to the next item"
The Welkin was certainly a major departure from the Whirlwind, and I would agree it was basically a new design, but it was also a much bigger change than the kind of incremental improvement we had previously discussed here. The Welkin was designed to operate at 45,000 ft, almost the top limit of a propeller powered aircraft in the WW2 era (or even now) and It had a pressurized cockpit with an entire extra supercharger just for that purpose! Almost the diametric opposite from the environment the Whirlwind was designed to fight in.
Something closer to the D.H. Hornet, but perhaps without such a radical redesign of the wing, seems a lot more feasible to me.
Something closer to the D.H. Hornet, but perhaps without such a radical redesign of the wing, seems a lot more feasible to me.
