Griffon vs Merlin rotation.

[megan]

The Griffon was developed at the request of the Fleet Air Arm.

War time aircraft that used the engine were various marks of the Naval Firefly and various marks of Spitfire, Seafire, Spiteful, Seafang, and sole MB.5. The Griffon Spitfire was the result of needing an aircraft to combat the appearance of the FW 190. Highest rated engine was the 101/121/130 version with two stage three speed supercharger installed in the Spiteful and Seafang, 2420 HP, 101 was single prop, the others contrarotating.

Rolls Royce had a project called the FTB (Flying Test Bed) which was built up primarily of P-51 components with the Griffon mounted behind the pilot as with the P-39. Mock up only built as the war ended and jets were seen as the way forward..

[nonsense]

https://en.wikipedia.org/wiki/Rolls-...d_developments

[blue up]

IIRC it was built up from one Mustang that got the tail chewed off and another that was dropped whilst being offloaded from a ship in Liverpool Docks. Eric Clutton wrote about it.

[Winemaker]

RE post #57 with the gear drive drawings, reversing the direction of rotation with the same camshafts would imply that the cam ramps were symmetrical on lift and return. Is this the case?

[nonsense]

Originally Posted by Winemaker

RE post #57 with the gear drive drawings, reversing the direction of rotation with the same camshafts would imply that the cam ramps were symmetrical on lift and return. Is this the case?

The gearing between crankshaft and camshafts reverses, not to reverse the direction of rotation of the camshafts, but to preserve the direction of rotation of the camshafts while reversing the crankshaft rotation. The camshafts turn the same direction regardless of the direction the prop turns.

[DaveReidUK]

Originally Posted by megan

Rolls Royce had a project called the FTB (Flying Test Bed) which was built up primarily of P-51 components with the Griffon mounted behind the pilot as with the P-39. Mock up only built as the war ended and jets were seen as the way forward..

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[megan]

The mockup was built up from components of AL960, AM148, and AM245. The first flight prototype was planned to have the tail surfaces of the Tempest. Remedial effort effort for the destabilisation effects of the additional power?

[stilton]

I just saw a documentary about the P38 confirming the three aircraft delivered to the RAF lacked superchargers and the contra rotating props of the American aircraft


Consequently their performance suffered greatly and they were rejected

[sycamore]

stilton ,the P-38 had counter-rotating props,not contra-rotating,which applies to props from one engine,ie Griffon.

[Winemaker]

Re the FTB P-51; wouldn't moving the engine back like that cause major c.g. problems? That's a huge hunk of iron to move back eight feet or so.

[pettinger93]

From memory, Eric 'Winkle' Brown has said in one of his books that the later marks of Mosquito DID have the two props rotating in opposite directions from each other, but that this was achieved by different gearing, rather than different engine rotations. This, he said, made the Mosquito one of his favourite wartime aircraft.

[DaveReidUK]

Originally Posted by pettinger93

From memory, Eric 'Winkle' Brown has said in one of his books that the later marks of Mosquito DID have the two props rotating in opposite directions from each other, but that this was achieved by different gearing, rather than different engine rotations. This, he said, made the Mosquito one of his favourite wartime aircraft.

I think there's confusion by him (or possibly you) between the Mosquito, which didn't have C/R props in any marks and the Hornet/Sea Hornet, which did.

[pettinger93]

Originally Posted by DaveReidUK

I think there's confusion by him (or possibly you) between the Mosquito, which didn't have C/R props in any marks and the Hornet/Sea Hornet, which did.

By 'C/R' do you mean 2 contra rotating props ? As far as I understood it, Eric Brown meant the single prop on one side went clockwise, and the other went counter-clockwise, thus eliminating swing. It was not a matter of maximising the power through the prop, just enhancing the behaviour of the aircraft. Am trying to find the book in which he said this, but it may takes some time. But of course, my memory may be faulty.

[pettinger93]

DaveReid: further : a quick search of wikipedia shows that Mosquito marks 32 and 34 PR models were powered by a Merlin 113 on one side and a 114 on the other. By searching for 'merlin 113 / 114' found a photo on another site that showed a photo of a mosquito with props with opposite pitch. But this is all very pedantic!

[pettinger93]

Unless Mr Brown was referring to the Hornet by mistake? (or my memory is failing even more than I thought) But I will shut up now.

[DaveReidUK]

Originally Posted by pettinger93

DaveReid: further : a quick search of wikipedia shows that Mosquito marks 32 and 34 PR models were powered by a Merlin 113 on one side and a 114 on the other.

That's correct. But AFAIK, the difference between the Merlin 113 and 114 wasn't the prop rotation, but the fact that the 114 (of which nearly twice as many were produced, compared to the 113: 1200 vs 650) had an additional supercharger for cabin pressurisation.

By searching for 'merlin 113 / 114' found a photo on another site that showed a photo of a mosquito with props with opposite pitch. But this is all very pedantic!

I'd be very interested to see that. There's a pretty conclusive photo and a lot of technical detail on the PR.34 here: This Day in Aviation: De Havilland DH.98 Mosquito PR.34