Best piston engine(s) for fighters of 1945?

[Shortround6]

They could have derated it to suit whichever application it was used for. Mass production of a single good engine model covers a lot of sins in terms of that engine not being perfectly optimal for some applications.

De-rated only works to a limited extent.
You can limit power by restricting rpm.
But the torque is the same until you get close to the RPM limit.

The British built over 17,000 tanks that could have used a 450hp V-12.
The Valentine is too small.
The 1700 Covenanters with their bespoke flat 12s were a total waste.
The 5300 Crusaders could certainly have used a better power pack.
The 500 Cavaliers
????Centaurs
Now throw in flat 12 used in 5600 Churchills and there was a pretty good quantity of engines that could be replaced even before you get to the Crowell,
Which had to have the final drives changed to slow the tank down to save the crew, suspension and tracks so sticking a 450-500hp engine in them wouldn't have hurt them much either.

15-17,000 engines of one type would be a pretty good run instead of 4 different ones. Save the Merlin's until you get to the Comet.

Sticking a 27 liter engine in a 30 ton tank when the Germans only had a 23 liter in Tigers and Panthers does seem to be a bit much.
Granted the British used few gears in the transmission.

 

[GregP]

R-3350 simply was not ready for WWII. Most B-29s did not return with all 4 engines running after a raid on Japan.

The post-war R-3350 got to BE reliable, but it was reliable because a flight engineer was on the throttle instead of a pilot. If you change rpm very gradually and mostly run it at one rpm, if could be VERY reliable. If you throttle-jockey it around on the ground, it will do a very good job of self destructing by way of bearing bits in the oil. Moral of the story is the R-3350 needed careful operating procedures to be reliable.

I'd stay with the R-2800. No bad issues after it got sorted out originally.

 

[pb43]

An interesting post made here by @Snowygrouch inspired me for this thread.
So between the piston engines of 1945, what ones do you think were the best? Or the best (ie. a singular), for that matter? We're probably looking at the best combination of power at all altitudes vs. the weight and size/drag penalty, with reliability as required for a service engine?
Only the engines that were actually flying back in 1945.

Rolls-Royce Eagle, without a doubt!

 

[marathag]

Was it the engine or cowling/mount?

Knew an USAF Lt Colonel who flew the B-32 and later the B-29 after the War with SAC.

part of the development team on the B-32 at Fort Worth, after he finished his B-24 missions over France and Germany

He said the B-32 had a fraction of the problem with burning up engines as the B-29 had. He suspected the cowling design, but admitted he never got a straight answer on that. He liked how the B-32 flew vs the B-29. Quite a change from the B-24, that he said was an awful plane to fly.

Too bad he's been gone for 25 years now. So much information, lost.

 

[GregP]

I've also heard very good stories about the B-32, but never gave them much thought because it was a low production count at 118 and only lasted in service from Jan - Aug 1945. It could not have had much of an impact and I just never followed up the nice things I heard about it.

It was about as fast as a B-29 and cruised about as fast, too.

You'd THINK that if it had a much lower engine failure rate using the same engine as the B-29, someone would have noticed and pointed it out to the USAAF, who SHOULD have been VERY interested in that fact. On the other hand, maybe they WERE interested but knew jets were just around the corner, and the B-36 was already in work.

Makes you wonder, doesn't it?

 

[tomo pauk]

Rolls-Royce Eagle, without a doubt!

Care to add some reasons for the choice, plus why it would've been better choice than some other powerful engines from 1945?

 

[z42]

De-rated only works to a limited extent.
You can limit power by restricting rpm.
But the torque is the same until you get close to the RPM limit.

You can also limit power by installing a smaller carb, or by limiting the max throttle valve opening. Or by a restrictor plate. All of which would also have limited torque, and not only max rpm. Early versions of the Meteor made 550 hp, a further 100 hp derating doesn't sound too drastic.

The British built over 17,000 tanks that could have used a 450hp V-12.
The Valentine is too small.
The 1700 Covenanters with their bespoke flat 12s were a total waste.
The 5300 Crusaders could certainly have used a better power pack.
The 500 Cavaliers
????Centaurs
Now throw in flat 12 used in 5600 Churchills and there was a pretty good quantity of engines that could be replaced even before you get to the Crowell,
Which had to have the final drives changed to slow the tank down to save the crew, suspension and tracks so sticking a 450-500hp engine in them wouldn't have hurt them much either.

15-17,000 engines of one type would be a pretty good run instead of 4 different ones. Save the Merlin's until you get to the Comet.

Sticking a 27 liter engine in a 30 ton tank when the Germans only had a 23 liter in Tigers and Panthers does seem to be a bit much.
Granted the British used few gears in the transmission.

I supposed you're angling for the Kestrel, as you mentioned in another thread. I don't think that would have been a bad choice, per se. IMHO the crucial advantage of a Kestrel based design would have been that they could have started the project much earlier, and thus the UK could have had a decent tank engine already when they started the buildout in preparation for the war.

The initial Kestrel introduced in 1927 produced 450 hp, and was naturally aspirated (like the later Meteor would also be). But I don't think there was much headroom in the design in terms of being able to produce more power using the pool petrol of the time, which was roughly 68 octane (probably RON, not sure how auto octane was measured in the UK back then?). Though in practice that 450 hp would have been sufficient for pretty much everything they fielded during the war.

But it's interesting to think of what would have happened if they had decided upon a 450 hp Kestrel based engine as "THE" standard tank engine in, say, the early 1930'ies. How would that have affected their tank designs that they ended up using in France, North Africa, and Italy in the early to mid war years?

However, when they historically decided they needed something better than the WWI era Liberty-based tank engines they had been used in their cruiser tanks up until then, I think the Merlin was the right choice. This allowed them to utilize Merlin parts that failed aero level quality inspection, or parts from crashed or damaged aircraft that they wouldn't dare to use in aircraft anymore, as well as to an extent take advantages of the economy of scale in Merlin manufacturing (tooling etc.). Also, some Meteors were made using parts from earlier marks of the Merlin engine that had become superfluous as the aircraft users had moved on to newer generation parts. As well has having plenty of headroom in the design, which then allowed them to imagine the concept of a heavy cruiser tank which evolved into the universal tank or MBT, although that was a postwar development.

As for the German experience with their Maybach HL 210/230, that wasn't exactly a happy one, with reliability problems, fires, blown gaskets and whatnot. Whether that was due to critical material shortages, their industry being bombed to bits, or just trying to push the design too hard given the technology of the day, I'm not sure.

 

[tomo pauk]

The British built over 17,000 tanks that could have used a 450hp V-12.

You can also limit power by installing a smaller carb, or by limiting the max throttle valve opening. Or by a restrictor plate. Early versions of the Meteor made 550 hp, a further 100 hp derating doesn't sound too drastic.

Perhaps the tank engines are worthy of their own thread?

 

[Geoffrey Sinclair]

Given their mechanical fragility armies prefer to move tanks by rail or transporter as much as possible, the 19th century decision by Britain's rail system on the spacing between tracks limited load width more than continental rail systems, that had a part to play in British tank designs.

You find WWII history in some interesting places. Journal of the American Statistical Association, V 41 no. 234, June 1946, pages 190 to 203. "Actuarial Analysis of the operating life of B-29 aircraft engines", by O L Altman and C G Goor. Lots of obvious and not so obvious points.

1) R-3350's were in critical supply in 1944 and the first half of 1945. Supply problems were easing around the end of the war.
2) Air transportation was used to send R-3350's to the US for overhaul, at best 2 R-3350's would fit in a cargo plane.
3) Overhauled engines had around 10% lower "life" before the next overhaul.
4) The -23 was the carburettor and the -57 the fuel injected versions. The -23 was modified to improve reliability.
5) The statisticians noted the standard USAAF methodology for forecasting engine life was only suitable for a reasonably static population. Not where there was a steady arrival of more strength using new aircraft.

In terms of engine life, operations in India were the worst, since each combat sortie required three reasonably rapid climbs, India to China, China to Japan, China to India. Next came training in the US, finally the best were the units in the Marianas.

Expected life prior to first overhaul, early operations from India, 163 hours, -23 engines. Using modified -23 engines this had risen to 280 hours by February/March 1945 for aircraft operating from India and 304 hours from the Marianas.

The figures for B-29s used in training were 221 hours and 310 hours versus the 163 and 280 hours figures above.

Operating from India a comparison between the modified and unmodified -23 engines showed 80% of the unmodified and 95.3% of the modified engines survived to over 100 hours, 33.9 of the unmodified and 81.5% of the modified engines survived to over 200 hours, 0.2% of the unmodified and 47.3% of the modified engines survived to over 300 hours.

In the Marianas, as of 20 November 1944 the average hours on each -23 engine removed was 91, by 20 January 1945 it was 151, as of 30 April it was 234. These figures include removals for engine model changes, modifications, accidents and battle damage. They are also under estimates of the normal engine lifetime because so many of the engines were new. The figures include new and overhauled engines, so it is either the number of hours since the engine was built for new engines or since overhaul for the overhauled engines.

Engine hours before removal as of 31 May was 259 hours, and 31 July 272 hours. These figures are for engines removed because of mechanical problems only.

Even in July the steady number of new B-29s arriving drove down the average engine hours per removed engine.

A study as of 31 July 1945 noted in the Marianas the -23 engines 96.8% of new and 92.5% of overhauled logged more than 100 hours before replacement, 87.5% and 75.7% respectively logged over 200 hours, 62.7% and 43.4% logged over 300 hours, 19% and 8% logged over 400 hours, none logged over 500 hours.

As noted above the training schools in the US went through R-3350 engines quicker than the combat units in the Marianas, for example 57.9% (new) and 36.4% (overhauled) logged over 300 hours, but once this mark was passed the engines in the US held up more, so 24.6% and 10.4% logged over 400 hours, and 1.2% and 0.2% managed over 500 hours.

The fuel injected -57 engine had a higher time between overhauls, so in the above study 31.2% used in training logged over 400 hours, and 4.9% logged over 500 hours.

 

[EwenS]

I've also heard very good stories about the B-32, but never gave them much thought because it was a low production count at 118 and only lasted in service from Jan - Aug 1945. It could not have had much of an impact and I just never followed up the nice things I heard about it.

It was about as fast as a B-29 and cruised about as fast, too.

You'd THINK that if it had a much lower engine failure rate using the same engine as the B-29, someone would have noticed and pointed it out to the USAAF, who SHOULD have been VERY interested in that fact. On the other hand, maybe they WERE interested but knew jets were just around the corner, and the B-36 was already in work.

Makes you wonder, doesn't it?

Problem was how few B-32 made it into combat to allow a proper assessment after its troubled development programme.

3 aircraft joined the 312th BG(Light) in May 1945 for service trials with about 10 two plane missions flown by the end of June. Another 6 were received by July to allow conversion of a whole Bomb Squadron with the rest of the Group due to convert by Oct (which never happened). Another 9 may have been received in Aug.

Their last mission on 28th Aug saw 2 aircraft readied. 1 was destroyed, losing an engine on take off, while the second lost 2 engines on the way home with crew members lost on bail out. And not the first reported engine failures.

The Bomber That Almost Wasn't

WWII's Convair B-32 Dominator never got the chance to live up to its name.

www.historynet.com

 

[z42]

Perhaps the tank engines are worthy of their own thread?

"Hey guys, get a room! Ooh, I feel so dirty now.."

Uh, now where was I? Oh yes, good idea. I started a thread about tank engines at Best tank engines of WWII

 

[marathag]

On the other hand, maybe they WERE interested but knew jets were just around the corner, and the B-36 was already in work.

He said that he knew the US would win the war, when he saw the prototype B-36 mockup and early deliveries of the Wasp Major at Convair Fort Worth.

 

[J.A.W.]

Back on fighter aircraft, the final iteration of the Hawker Typhoon/Tempest/Fury line was unwanted by the RAF as a fighter,
due to the advent of the turbo-jet, yet the new turbines were excessively fuel hungry, especially at low altitude,
so the piston engine powered planes still had a role as fighter-bombers. See the link below for a contemporary report.

http://www.wwiiaircraftperformance.org/Fury/Sea_Fury_Flight.pdf

The Hawker Fury prototypes flew with all three 2,000hp+ big British mills (Bristol Centaurus/Napier Sabre/Rolls-Royce Griffon),
& just as per the Tempest, was fastest with Sabre power up front.

In the event, the RAF rejected the Sabre-Fury - largely due to the area of radiator presented as a target for ground fire,
whereas fitted to the Tempest Mk VI with uprated Sabre - it could utilize the armour as already produced for the Typhoon
- to protect the more compact chin radiator.

The Tempest Mk VI was issued to RAF units to replace their Mustang Mk IVs (P-51D/K) due to Lend-Lease stipulations,
& the pilots reported the change positively, as quoted below from the 213 Squadron ORB account (page 5, Jan 27th 1947)

"...F/Lt Johnson flew the Tempest for the first time. He was heard to remark afterwards:
'It's a lot of aeroplane - and it certainly makes Cyprus small' As the Tempest cruises effortlessly
at 70mph more than the Mustang IV, the last remark was quite true."

Oddly enough, since the R/R Griffon was intended for Royal Navy FAA service, and was aboard carriers already,
in Firefly & Seafire, it too was rejected as the mill for the Sea Fury, with the Big Bristol getting that gig.

 

[tomo pauk]

The Hawker Fury prototypes flew with all three 2,000hp+ big British mills (Bristol Centaurus/Napier Sabre/Rolls-Royce Griffon),
& just as per the Tempest, was fastest with Sabre power up front.

Any insight of speed achieved for the Griffon-powered Fury?

In the event, the RAF rejected the Sabre-Fury - largely due to the area of radiator presented as a target for ground fire,
whereas fitted to the Tempest Mk VI with uprated Sabre - it could utilize the armour as already produced for the Typhoon
- to protect the more compact chin radiator.

Funny thing, the RAF love/hate relatioship with radiator set-ups.
They green-lit the Tempest I (despite the large area radiators), then said 'no; use the beard radiator instead', so we get to Tempest V. However, they had no problems allowing the Spiteful/Seafang with the large area radiators, nor with the Hornet, again green-lit the Tempest Fury with the large area radiators, then saying 'no', but this time without allowing that beard radiator is installed.

Again, funny thing.

"...F/Lt Johnson flew the Tempest for the first time. He was heard to remark afterwards:
'It's a lot of aeroplane - and it certainly makes Cyprus small' As the Tempest cruises effortlessly
at 70mph more than the Mustang IV, the last remark was quite true."

Any math behind this?

Oddly enough, since the R/R Griffon was intended for Royal Navy FAA service, and was aboard carriers already,
in Firefly & Seafire, it too was rejected as the mill for the Sea Fury, with the Big Bristol getting that gig.

After VE day, RN's "pie" was shrinking big time. Giving all of it to just one engine company was probably not seen prudent.

 

[J.A.W.]

Any insight of speed achieved for the Griffon-powered Fury?



Funny thing, the RAF love/hate relatioship with radiator set-ups.
They green-lit the Tempest I (despite the large area radiators), then said 'no; use the beard radiator instead', so we get to Tempest V. However, they had no problems allowing the Spiteful/Seafang with the large area radiators, nor with the Hornet, again green-lit the Tempest Fury with the large area radiators, then saying 'no', but this time without allowing that beard radiator is installed.

Again, funny thing.



Any math behind this?


After VE day, RN's "pie" was shrinking big time. Giving all of it to just one engine company was probably not seen prudent.

"Disappointing" was the term applied to the performance of the Griffon in the Fury, (I've never seen any official figures - where are those
Hawker factory flight tests now? I'd like to see what the 2nd Sabre-Fury VP 207 achieved with its Sabre on +20lb boost).

IIRC, 'cropped' tips were tried on the contra-prop Griffon-Fury, to check if tip-speed was the issue, but to no avail.

The Supermarine Spiteful/Seafang were both rejected, partly due to inferior low-speed handling characteristics, and the ready
availability of late mark Spitfire/Seafire with fairly good high-speed/altitude performance (& jets now had that role, per RAF),
plus the Hawker machines had proven to be the more effective fighter-bombers during 2nd TAF wartime service.

Yeah, the politico-economic standing of manufacturing is always lurking in the background, ever wondered how a Firefly
would've performed with an FAA-spec Sabre (as flown in 20+ Firebrands) but fitted with a contra-prop?

 

[tomo pauk]

The Supermarine Spiteful/Seafang were both rejected, partly due to inferior low-speed handling characteristics, and the ready
availability of late mark Spitfire/Seafire with fairly good high-speed/altitude performance (& jets now had that role, per RAF),
plus the Hawker machines had proven to be the more effective fighter-bombers during 2nd TAF wartime service.

Neither Spiteful nor Seafang was rejected due to having the 'large area radiators', my point.

 

[J.A.W.]

Neither Spiteful nor Seafang was rejected due to having the 'large area radiators', my point.

It may've still been on the list, but down it someway - below the most cogent reasons - for rejection.

 

[tomo pauk]

It may've still been on the list, but down it someway - below the most cogent reasons - for rejection.

In other words - it can't be proved, just speculation?

 

[J.A.W.]

In other words - it can't be proved, just speculation?

Likely not as 'loose' as "speculation", more of a fair probability - if unverified through official sources - albeit the
well-known Air Ministry 'bugbear' was 'wing leading edge radiators' which technically - the Spiteful didn't have...

 

[gumbyk]

Moral of the story is the R-3350 needed careful operating procedures to be reliable.

And to put that into perspective, more modern radials require comparatively careful operation, when compared to something like a Lycoming or Continental.
Three seconds to full throttle, ensuring that the prop isn't driving the engine, etc.