Redesigning the Defiant.

[stona]

Thanks for that. Douglas' minute was regarding the Blenheim as a nightfighter,dated 28th August 1940,and was part of the back stabbing campaign he was conducting against Dowding at the Air Ministry.
His 15 mph estimate ties in with the stuff you posted for the Blenheim I. You don't happen to know if that test was carried out prior to Douglas' memo? If those were the results to which he was referring Douglas,typically,didn't mention the 250 hours of surface preparation,nor the clipped wings or fairing.
Cheers
Steve

 

[Shortround6]

The book doesn't give the dates for this but does say that the plane was assigned to and worked on by Cotton's No.2 Camouflage Flight before it it (the flight) became fully operational. two Blenheims were assigned but only one was modified. The same plane "pioneered" the use of the "SKY" color ( duck-egg blue) and this effort predates Cotten getting his first Spitfire for the unit.
Mention is made of Dowding inspecting the 'high-speed' Blenheim and asking for eight more to be modified due to the inadequate performance of the MK IF fighters. It is unknown if any work was ever done on this request. It was during this inspection that Cotton requested his first two Spitfires so it may have been in 1939??

 

[stona]

That definitely predates April 1940. Up until that time the colour used by Cotton was called "Camotint". A letter to Bristol of 20th April 1940 concludes:

"As regards colour the pale blue-green colour which has been called Camotint is now defined as Standard Sky,and this description should be given in your schedule."

I'm confident that Douglas was using data from these tests in 1939/40 and misrepresenting it somewhat in his efforts to discredit Dowding.

Cheers

Steve

 

[nuuumannn]

The turretless redesign smacks of the sort of desperation shown by aircraft manufacturers on both sides to get something ordered and prevent a loss of contract.

Well, not quite the case as by the time it was working on the P.94, BP had received the contract to build the Defiant Mk II and the Roc, so not such a 'desperate measure' as you describe, Steve. The P.94 was designed as a stop-gap using as many Defiant sub assemblies, so wasn't a 'Defiant-without-a-turret'. Alec Brew in 'The Defiant File' states that flight tests carried out by K8310 without a turret led to the projected performance; presumably the test figures are in an archive somewhere and would make interesting reading and hopefully answer our predictions. BP also proposed a more basic conversion of the Defiant with four .303s in the wings. There's no doubt that that wouldn't have been so quick.

There was also a project to fit a low drag wing to the Defiant;

"The wing would have a thickness of 18% at the root and 9% at the tip and the area would be reduced from 250 sq ft to 232 sq ft by fitting a smaller centre section, though the outer wings would be slightly larger in area. The Defiant with the low drag wing was estimated to have a Drag-co-efficient of 0.0202 as against 0.0273 for the normal Defiant and an estimate of 0.024 for BP's P.94."

Although the low drag wing Daffy was proposed in 1941 and an aircraft had its wings modified and turret removed whilst testing at Farnborough, looks like the P.94 might have had a modified wing planform over the standard Defiant wing at any rate, so its projected figures might not have been as optimistic as we believe (although I'm cautiously willing to go down to 345 mph from 350! The Hurricane IIb could do 340 mph with 12 x .303s and the Hurri IIa, 342 mph with 8 x MGs). Having never having been built, we'll probably never know just how much less the prformance of the P.94 was than its projected figures. Now, where are those flight test figures...

 

[tomo pauk]

I'm not sure that a wing of 18% thickness at the root could be called a low drag wing. The Typhoon was "19.5% at the root tapering to 12% at the tip", Tempest was down to "14.5% at the root, tapering to 10% at the tip". Spitfire went further, "13% at the root, reducing to 9.4% at the tip". All quotes from Wikipedia, I'll welcome the corrections.

The drag coefficient for Spitfire V was ~0,0215, expecting from a plane with 18% 'thick' wing to better that by some 10% is not very realistic.

Although the low drag wing Daffy was proposed in 1941 and an aircraft had its wings modified and turret removed whilst testing at Farnborough, looks like the P.94 might have had a modified wing planform over the standard Defiant wing at any rate,...

If I'm reading this right, there was a Defiant with different/modified wings?

 

[nuuumannn]

If I'm reading this right, there was a Defiant with different/modified wings?

No, it was never completed; the aircraft in question had its wings removed, but no further work was done.

Although you provide figures, which I'm assuming are right since I don't know any better, (although they are from Wiki!) it is worth mentioning that the Spitfire had an unusually thin wing for the time; what we might think are not 'low drag', in 1940/41 they might do so compared to other contemporary aircraft, so the term 'low drag wing' is, of course relative.

The drag coefficient for Spitfire V was ~0,215, expecting from a plane with 18% 'thick' wing to better that by some 10% is not very realistic.

You might well be right.

 

[Kevin J]

With it's wider undercarriage track, space for large extra tank near the centre of gravity, a cockpit slightly further forward than the Spitfire/Hurricane and a substantial centre section to mount wing fold joints the Defiant has been a perennial favourite in forums to be the FAA fighter it needed.

Not only did Boulton Paul install 8 x .303 in K8310 but did the design work for 4 x 20mm.

The production of the Defiant was far easier than a Spitfire and would have made shadow factories quicker to set up and disperse production and you would not have to build Fulmars or Sea Gladiators nor use shipping for Martlets.

However, remember that in OTL the Defiant was only coming fully on stream in mid 1940 and making them construct Blackburn's Roc's was no help.

The advantage that the Sea Hurricane had above all other fighters was that it was a field mod. You changed the radio and attached a tail hook and if required added catapult spools. Spare aircraft could be stored below decks dismantled. If it had previously had a tropical/dust filter, you could simply replace it with the standard one. It was available globally. Top speed of the Hurricane IIC was 291 mph at sea level and 342 mph at 22000 feet compared with 280 / 345 mph for the Seafire IIC. I doubt if a fully loaded Sea Defiant II with full armament would exceed 335 mph in flight. As an interim, immediately available FAA fighter, the Sea Hurricane was equal in performance to both the A6M2/3 and Wildcat in all regards except for range. I'd chose the Sea Hurricane over the Sea Defiant in the short term and the Seafire in the long term.