Engine choices for P-51 mustang ?

[SaparotRob]

That’s a pretty cool airplane.

 

[wuzak]

One of the differences between a V-1710 or V-1650 and a radial like the R-2800, are the main bearings.

In the inline engines, the crank is "floating" between the bearings by means of hydraulic pressure. Once damage has occurred to the engine, resulting in loss of oil pressure, the crankshaft starts grinding on the bearings and engine seizure is soon to follow.
In the radial, the main bearings were roller bearings that relied on a "wash" to keep them lubricated, so a loss of oil pressure did not result in the same failure as the above-mentioned.
Add to this, that the radial was not dependant on liquid coolant to operate, so damage that resulted in loss of it's oil would not cause immediate failure.

The R-2800 didn't have roller main bearings or big end bearings.

 

[EwenS]

Indeed, for the Westland Wyvern.

I think it is a bit of a stretch to say they were developed for the Wyvern. The Wyvern was seen as one potential use for them but its Spec was originally written around a piston engine.

The initial Spec N.11/44 dated Jan 1945 for the Wyvern specified the use of the Rolls Royce 24 cylinder Eagle engine (the 1944 Eagle with H cylinder layout, not the WW1 engine of the same name). The design was to be such that the wings and if possible the tailplane, fin and rudder could be fitted to a different fuselage to take a turboprop.

The prototype Wyvern TF.1 flew in Dec 1946 with the Eagle engine followed by 5 other prototypes and an order in June 1946 for 20 pre-production aircraft of which 7 were completed. The last of the latter, VR137 which never flew, is now preserved at the Fleet Air Arm Museum at Yeovilton as the sole remaining Wyvern.

When Rolls Royce decided not to continue developing the Eagle the Spec was rewritten as N.12/45 issued to Westland in Jan 1946 to be powered by a Rolls Royce Clyde turboprop. The first Clyde powered prototype Wyvern TF.2 flew in Jan 1949 and was followed by 2 more powered by the Armstrong Siddeley Python turboprop. It was the latter engine that powered the remaining Wyverns after RR decided to concentrate on developing the Avon jet engine and dropped the Clyde (although it formed the starting point for the later Dart).

As originally specified the role envisaged in both N.11/44 and N.12/45 was as a gun armed aircraft for air combat with a secondary land and sea attack function. It took so long to develop that it finally entered front line service in the strike role in Feb 1953.

 

[swampyankee]

The Brits were working on a turbo prop engine during WW2.

You mean the Gloster Trent-Meteor? Gloster Trent-Meteor - experimental aircraft

 

[PAT303]

The R-2800 didn't have roller main bearings or big end bearings.

Part of the start up procedure of the R2800 is to turn the engine over to drain the oil from the bottom cylinders and pre oil the main bearings so they aren't scuffed.

 

[FLYBOYJ]

Part of the start up procedure of the R2800 is to turn the engine over to drain the oil from the bottom cylinders and pre oil the main bearings so they aren't scuffed.

IIRC the sparkplugs are removed from the bottom cylinders and then the prop is pulled through by hand several revolutions, especially if the aircraft was sitting for awhile.

 

[PAT303]

IIRC the sparkplugs are removed from the bottom cylinders and then the prop is pulled through by hand several revolutions, especially if the aircraft was sitting for awhile.

Is this true of all radials?.

 

[FLYBOYJ]

Is this true of all radials?.

All? IDK, Most? I would say yes...

 

[wuzak]

One of the differences between a V-1710 or V-1650 and a radial like the R-2800, are the main bearings.

In the inline engines, the crank is "floating" between the bearings by means of hydraulic pressure. Once damage has occurred to the engine, resulting in loss of oil pressure, the crankshaft starts grinding on the bearings and engine seizure is soon to follow.
In the radial, the main bearings were roller bearings that relied on a "wash" to keep them lubricated, so a loss of oil pressure did not result in the same failure as the above-mentioned.
Add to this, that the radial was not dependant on liquid coolant to operate, so damage that resulted in loss of it's oil would not cause immediate failure.

This is not to say that it would run indefinitely in the event of critical damage, but it would far outlast an inline that suffered comparable damage.

Also, meant to mention that the Daimler Benz inverted V-12s had roller big end bearings (mains too?) for a while.

 

[Mike Williams]

Sadly (or not... I`m not sure sometimes) I missed proceedings by three quarters of a century. But I was told by the son of one Battle of Britain pilot (would have to go look up the squadron, but Lionel Goddard was the pilots name), that many in his squadron (which did unusually well) had a load of engine mechanics who had been motorcycle racing people in peacetime. He claims that they did lots of little bits on their pilots Merlins, like cutting the valve seats into three angles instead of one, and so on.

However, this is not something I`m in any position to prove.

I was reminded of this topic when reading about Evan Mackie from when he served with 243 Squadron in North Africa.

"At about this time (mid April 1943) Mackie managed to wangle for himself a set of 12 special stub exhausts for his Spitfire VC, of the type then fitted only to Mark IXs."
"They gave the aircraft a few more miles per hour..."
"Mackie was known to be very proud of his special exhausts" p.77

"I was firing and I was well within range and I was really scoring hits - and the next thing another Spitfire from above came down and knocked my propeller blades forward.'
"I had just enough power to carry out a wheels up landing in, would you believe, a field of wheat in Tunisia."

"The next morning I borrowed a spanner and took off my special little stub exhausts, which at the time were just coming into use. I got the first set and nobody else had them. So I took them off, put them in a sack and arrived home by army truck the next day." p.80

"Mackie was given a new Spitfire VC on his return and the machine was fitted with the stub exhausts". p.81

Spitfire Leader, The Story of Wing Cdr Evan "Rosie" Mackie, Avery & Shores, Grub Street, London 1999