Best piston engine(s) for fighters of 1945?

[J.A.W.]

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.

FWIW, one 'fighter aircraft engine' attribute Len Setright ascribed to the Sabre, was 'its ability to blip up & down the rpm meter like a car'.

 

[J.A.W.]

Any math behind this?

tomo, the remark* is supported by the Tempest's Sabre VA being capable of running at its low level normal/climb power setting for an hour,
which allows the pilot to utilize 2000+hp for that period, a quantum of power/time which the V-1650-7 powered Mustang IV can't match.

*Refers to post #34:
"...Tempest cruises effortlessy at 70mph faster than the Mustang IV."
A quote from the 213 Squadron ORB, on replacing their Mustangs with Tempests.

Edit: Noted post # for reference.

 

[Metrallaroja]

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.

I have to go with the R-2800-18W, very powerful yet compact and in combat in 1945 in the F4U-4:

Spoiler: R-2800-18W

 

[J.A.W.]

I have to go with the R-2800-18W, very powerful yet compact and in combat in 1945 in the F4U-4:
View attachment 759317
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Spoiler: R-2800-18W

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Pretty good for an air-cooled radial (once it had received a couple of major makeovers to increase heat-rejection) but those outputs
were a tad 'ephemeral' power-setting endurance-wise. What was the R-2800 able to make in 'normal power' mode, & for how long?

 

[Metrallaroja]

Pretty good for an air-cooled radial (once it had received a couple of major makeovers to increase heat-rejection) but those outputs
were a tad 'ephemeral' power-setting endurance-wise. What was the R-2800 able to make in 'normal power' mode, & for how long?

 

[Metrallaroja]

Water Injection 60'' or even 70'' can be used very safely in intermitent 5 minutes periods until water is out (around 12 minutes of use).
Military 55'' 2100-1880-1700 can be used in intermitent 5-15 minutes periods, unlimited.
Normal 47-49'' 1700-1630-1550 can be used in unlimited periods.

 

[J.A.W.]

Water Injection 60'' or even 70'' can be used very safely in intermitent 5 minutes periods until water is out (around 12 minutes of use).
Military 55'' 2100-1880-1700 can be used in intermitent 5-15 minutes periods, unlimited.
Normal 47-49'' 1700-1630-1550 can be used in unlimited periods.

Ta for that, but note the Napier Sabre VA had a 'normal' power-level of over 2,000hp, also good for as long as the fuel lasts.

 

[tomo pauk]

Water Injection 60'' or even 70'' can be used very safely in intermitent 5 minutes periods until water is out (around 12 minutes of use).
Military 55'' 2100-1880-1700 can be used in intermitent 5-15 minutes periods, unlimited.
Normal 47-49'' 1700-1630-1550 can be used in unlimited periods.

Excellent choice, the -18W.
At 26000 ft, it was making 500 HP more than the vaunted Sabre VII.

 

[Shortround6]

Ta for that, but note the Napier Sabre VA had a 'normal' power-level of over 2,000hp, also good for as long as the fuel lasts.

Where did that come from?

Sabre power figures are all over the map.
They are worse than Merlin figures.
The Sabre VA engine didn't show up in service until about when the war ended, In Tempest VI aircraft.
There was often a considerable time between even flight test and operational/squadron use.

My summer of 1945 engine can beat your summer of 1944 engine, just like trying to use last years FI racer in this season.
A Merlin 66 in high gear only makes 1310hp at best altitude for the British max continuous rating. It also only weighed 1645lbs for a weight to power ratio of 1.25lbs/hp
The Sabre V made 1930hp at about the same altitude (both engines in high gear) but weighed about 2500lbs for weight to power ratio of about 1.29lbs/hp

Not seeing the advantage of the 1946 engine over the 1942 engine???

and if you are using 2000hp to cruise with you are landing pretty darn soon, with anyone's engine.

*Refers to post #34:
"...Tempest cruises effortlessy at 70mph faster than the Mustang IV."
A quote from the 213 Squadron ORB, on replacing their Mustangs with Tempests.

a bit of hyperbole perhaps?
or only applicable to certain conditions?

P-51D flight chart

http://www.wwiiaircraftperformance.org/mustang/p_51_flightopschart_199.jpg

Seems like a clean Mustang (or with bomb racks) could do 350mph at 15,000ft at a fairly economical cruise setting (middle column)
The Tempest could cruise at 420mph?
Or pick another altitude and speed like 5000ft and 340mph, Mustang is pushing it at 2700rpm and 46in but that is the limit of max continuous. Can the Tempest cruise at 410mph at 5000ft?

 

[drgondog]

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?

I suspect that not enough reasons existed to remotely consider replacing B-29 with the B-32.

 

[tomo pauk]

a bit of hyperbole perhaps?
or only applicable to certain conditions?

P-51D flight chart
http://www.wwiiaircraftperformance.org/mustang/p_51_flightopschart_199.jpg
Seems like a clean Mustang (or with bomb racks) could do 350mph at 15,000ft at a fairly economical cruise setting (middle column)
The Tempest could cruise at 420mph?
Or pick another altitude and speed like 5000ft and 340mph, Mustang is pushing it at 2700rpm and 46in but that is the limit of max continuous. Can the Tempest cruise at 410mph at 5000ft?

Seems to me that you have missed the part concerning the valve train on the engine of Tempest II - it is, after all, the common knowledge that sleeve valves are contributing to the aircraft's performance the same way as the balkenkreutze did.

 

[GTX]

Tank Transmissions (and steering gear) can weigh as much as the engines and they take up a fair amount of volume in the armored hull.

For example - this is the M1 Abrams AGT1500 & X1100 transmission:

 

[J.A.W.]

Where did that come from?

Sabre power figures are all over the map.
They are worse than Merlin figures.
The Sabre VA engine didn't show up in service until about when the war ended, In Tempest VI aircraft.
There was often a considerable time between even flight test and operational/squadron use.

My summer of 1945 engine can beat your summer of 1944 engine, just like trying to use last years FI racer in this season.
A Merlin 66 in high gear only makes 1310hp at best altitude for the British max continuous rating. It also only weighed 1645lbs for a weight to power ratio of 1.25lbs/hp
The Sabre V made 1930hp at about the same altitude (both engines in high gear) but weighed about 2500lbs for weight to power ratio of about 1.29lbs/hp

Not seeing the advantage of the 1946 engine over the 1942 engine???

and if you are using 2000hp to cruise with you are landing pretty darn soon, with anyone's engine.


a bit of hyperbole perhaps?
or only applicable to certain conditions?

P-51D flight chart

http://www.wwiiaircraftperformance.org/mustang/p_51_flightopschart_199.jpg

Seems like a clean Mustang (or with bomb racks) could do 350mph at 15,000ft at a fairly economical cruise setting (middle column)
The Tempest could cruise at 420mph?
Or pick another altitude and speed like 5000ft and 340mph, Mustang is pushing it at 2700rpm and 46in but that is the limit of max continuous. Can the Tempest cruise at 410mph at 5000ft?

You can consult your Wilkinson for the Sabre VA power levels, and correlate them with the power/altitude graphs posted recently.

The Sabre VA was ~contemporary as a service engine, with the R-2800-C, but earlier Tempest units, in wartime ops also utilized the
Sabre's 'normal/climb' power setting for 'armed recce' fighter interdiction sweeps, in fact one Wing Commander (Flying) J.B. Wray,
(who did 'bag a brace' of Me 262s) was nicknamed "45 minute Wray" for his method of doing so.

R. Beamont another Tempest Wingco described a fast cruise speed of "365 IAS" at tactical heights*, & J. Sheddan a veteran 486 NZ Sqd
pilot who'd flown numerous op sorties in both Typhoon & Tempest even remarked that sometimes they'd deliberately do a slow cruise
which the Tempest pilots hoped would make the LW controllers think them to be lesser foes to take on, & so "send up some trade".

*8-10,000ft, 'where the light flak was curling under beneath, & below useful height for the heavy stuff, yet still with a good view'.

 

[J.A.W.]

Seems to me that you have missed the part concerning the valve train on the engine of Tempest II - it is, after all, the common knowledge that sleeve valves are contributing to the aircraft's performance the same way as the balkenkreutze did.

Well, certainly in efficiency terms, ex-Spitfire ace & Hawker test pilot Neville Duke flew a delivery flight across to the Middle East in a Hawker
fighter equipped with a Centaurus mill postwar, & on the London-to-Rome 1st leg - duly beat the speed/distance record only just set -
by the DH Vampire turbo-jet!

 

[tomo pauk]

Well, certainly in efficiency terms, ex-Spitfire ace & Hawker test pilot Neville Duke flew a delivery flight across to the Middle East in a Hawker
fighter equipped with a Centaurus mill postwar, & on the London-to-Rome 1st leg - duly beat the speed/distance record only just set -
by the DH Vampire turbo-jet!

People that were flying P-82s didn't gotten them memo that said 'either sleeve valves or nothing' when they were making record-setting flight of 5000+ miles non-stop.

 

[J.A.W.]

People that were flying P-82s didn't gotten them memo that said 'either sleeve valves or nothing' when they were making record-setting flight of 5000+ miles non-stop.

They never had the option, did they? (That P-82 Betty-Jo, must've been loaded with almost as much gas as a late-model P-47!).

Given the Tempest test-flight report written by the USAAF in late 1943 - they'd have liked to have a reverse Lend-Lease option - on it.

http://www.wwiiaircraftperformance.org/tempest/Tempest-V-Eng-47-1658-C.pdf

 

[J.A.W.]

Excellent choice, the -18W.
At 26000 ft, it was making 500 HP more than the vaunted Sabre VII.

Not much use for a fighter-bomber at 26,00ft, is there - unless Tibet needed a rake-over...

 

[J.A.W.]

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.

Here's an informative piece on how Chrysler Corp dealt with Wright engines under the pressure of the top priority B-29 program:

https://www.allpar.com/history/military/b-29.html

Note the comments about how the R-3350 "...often ingested its own valves", but hey - they were poppets, not sleeves...

Edit: fixed typo.

 

[J.A.W.]

Where did that come from?

Sabre power figures are all over the map.
They are worse than Merlin figures.
The Sabre VA engine didn't show up in service until about when the war ended, In Tempest VI aircraft.
There was often a considerable time between even flight test and operational/squadron use.

My summer of 1945 engine can beat your summer of 1944 engine, just like trying to use last years FI racer in this season.
A Merlin 66 in high gear only makes 1310hp at best altitude for the British max continuous rating. It also only weighed 1645lbs for a weight to power ratio of 1.25lbs/hp
The Sabre V made 1930hp at about the same altitude (both engines in high gear) but weighed about 2500lbs for weight to power ratio of about 1.29lbs/hp

Not seeing the advantage of the 1946 engine over the 1942 engine???

and if you are using 2000hp to cruise with you are landing pretty darn soon, with anyone's engine.


a bit of hyperbole perhaps?
or only applicable to certain conditions?

P-51D flight chart

http://www.wwiiaircraftperformance.org/mustang/p_51_flightopschart_199.jpg

Seems like a clean Mustang (or with bomb racks) could do 350mph at 15,000ft at a fairly economical cruise setting (middle column)
The Tempest could cruise at 420mph?
Or pick another altitude and speed like 5000ft and 340mph, Mustang is pushing it at 2700rpm and 46in but that is the limit of max continuous. Can the Tempest cruise at 410mph at 5000ft?

Check the Sabre's 'max climbing' (~'normal) power/height line graphed in the attachment linked below.

Sabre makes over 2,000hp from S-L to 12,000ft & over 1,900hp on up to 19,000ft at 3,700rpm/+10.5lb boost.

Sabre VII is 'wet' variant of Sabre VA, but the ADI wasn't used at those power settings.

Edit 1: guess another issue to work out would be the old IAS or TAS question?

Edit 2: The chart below shows how ^ boosting the Sabre & the speed increase in Tempest,
duly noting that this was early 1944, & max-boost then - became a 'normal' setting by 1945.

http://www.wwiiaircraftperformance.org/150grade/rae-1501-fig2.jpg

 

[Shortround6]

Check the Sabre's 'max climbing' (~'normal) power/height line graphed in the attachment linked below.

Sabre makes over 2,000hp from S-L to 12,000ft & over 1,900hp on up to 19,000ft at 3,700rpm/+10.5lb boost.

Sabre VII is 'wet' variant of Sabre VA, but the ADI wasn't used at those power settings.

Edit: I guess another issue to work out would be the old IAS or TAS question?

I am looking, I have also looked at the Griffon 69 mentioned on the page 4 of attachment. 2375hp.

What it rather interesting is that 2130hp is claimed at 15,500ft while the Sabre engine is about 2450hp at the same altitude on the graph in the article.
At 21,000ft the difference in power is a lot closer. The Griffon engine is over 450lbs lighter and the article claims a specific weight of 0.88lb/hp (low gear, max boost)
The specific weights I gave earlier were for max cruise.

edit. a lot of these engines have specs that bounce all over the place depending on when the specs were quoted. The Article explains rather well the differences between the late model Sabres and the earlier ones, there was a lot more than just screwing around with the boost settings
Even the article on the Griffon engine is about the changes in the power listed from an earlier article.