R2800 Engines for the B-17s/B-24s ?

Tham · Jul 19, 2007

I've always wondered why the Pratt Whitney R2800 was
not used in B-24s and B-17s during the war, rather than the
badly underpowered Wright R1820 ?

The turbocharged, water-methanol injected 2,800 hp R2800-57
engine would easily have taken both bombers to 300 mph and
a operational height of 30,000 feet (equivalent to B-29 performance),
rather than 180 mph and 20,000 feet with the R1820.

This would obviously have made interception by German fighters
much more difficult (equivalent to Japanese difficulty in intercepting
B-29s), cut losses drastically and saved immeasurable lives.

What is ironical is even the little Lockheed Hudson were given
R2800s to replace their R1830s and become the mediocre PV-1
Ventura, which was hardly used anyway.

FLYBOYJ · Jul 19, 2007

Tham said:
I've always wondered why the Pratt Whitney R2800 was
not used in B-24s and B-17s during the war, rather than the
badly underpowered Wright R1820 ?

The turbocharged, water-methanol injected 2,800 hp R2800-57
engine would easily have taken both bombers to 300 mph and
a operational height of 30,000 feet (equivalent to B-29 performance),
rather than 180 mph and 20,000 feet with the R1820.

This would obviously have made interception by German fighters
much more difficult (equivalent to Japanese difficulty in intercepting
B-29s), cut losses drastically and saved immeasurable lives.

What is ironical is even the little Lockheed Hudson were given
R2800s to replace their R1830s and become the mediocre PV-1
Ventura, which was hardly used anyway.

1. The B-17 was not underpowered
2. The R-2800 wasn't around when the B-17 was being designed
3. Although more powerful, you don't always gain extra performance by adding more powerful engines. Fuel consumption, weight and possibly range might be affected. In addition the extra power would result in airframe modifications. there is a possibility of the airframe still having problems as that engine wasn't originally designed to fit the B-17 airframe.
4. For the little performance that might of been gained, it was not worth stopping the B-17 production lines and diverting engineers away from other more critical projects.
5. The B-29

syscom3 · Jul 19, 2007

I dont think the early R2800's were known for fuel economy.

Any gain made by using the early model R2800's was going to be offset by reduced payload and range.

Graeme · Jul 19, 2007

Tham said:
What is ironical is even the little Lockheed Hudson were given
R2800s to replace their R1830s and become the mediocre PV-1
Ventura, which was hardly used anyway.

The Ventura provided good service for the RAAF. They participated in the Eindhoven raid against the Philips factory in December 1942. The RAAF received 75 Venturas, supplied under Lend-Lease, the last two being sold off not until the 17th February 1953. I saw one at an air show (belonging to RAAF Point Cook)
years ago and remember the broadcaster mentioning that 'low down' the Ventura was faster than the A6M.

Tham · Jul 20, 2007

FLYBOYJ said:
Although more powerful, you don't always gain extra performance
by adding more powerful engines. Fuel consumption, weight and
possibly range might be affected. In addition the extra power would
result in airframe modifications. there is a possibility of the airframe
still having problems as that engine wasn't originally designed to fit
the B-17 airframe.

Thank you for the information, FlyboyJ.

Yes, I realize only the R1820/1830 was available when the
B-17 and B-24 were designed. However, I think conversion
to the R2800, or at least the R2600, would not have been too
difficult, given the large size of both bomber's wings and the
relative soundness of their fuselages. The Hudson's airframe
didn't appear to need a radical redesign to become the Ventura,
apart from a longer fuselage, althought it ended up with a
higher wing loading.

Then again, production constraints during the war would have
been a major factor against it.

The R2800 was one fuel guzzler and apparently used up
some 100 gallons per hour in P-47s. Operating radius in
the bombers would have decreased, but I think with the
huge fuel tanks in their wings, plus improved power/weight
ratio, there would still be sufficient reserves to reach deep
into Germany.

The Ventura was some 70 mph faster than the Hudson,
and climbed almost twice as fast. The R2800-31 version
used in the Ventura did not appear to be turbocharged.
I think turbocharging it would have taken the B-17 and
B-24 to an operating ceiling of at least 30,000 feet.

Graeme said:
I saw one at an air show (belonging to RAAF Point Cook)
years ago and remember the broadcaster mentioning that
'low down' the Ventura was faster than the A6M.

Yes, I had underrated the Ventura and it indeed looks like
one quite hot aircraft.

Koster 1/48 PV-1 Ventura by Terry Miesle

FLYBOYJ · Jul 20, 2007

Tham said:
Thank you for the information, FlyboyJ.

Yes, I realize only the R1820/1830 was available when the
B-17 and B-24 were designed. However, I think conversion
to the R2800, or at least the R2600, would not have been too
difficult, given the large size of both bomber's wings and the
relative soundness of their fuselages. The Hudson's airframe
didn't appear to need a radical redesign to become the Ventura,
apart from a longer fuselage, althought it ended up with a
higher wing loading.

Sometimes engine conversions don't work when they seem real easy. I work with DHC-6 Twin Otters. We went to an increased horsepower PT6 engine and now we're tearing up engine mounts. We're still investigating why but these are some of the things you encounter with a seemingly easy engine upgrade...

johnbr · Jul 21, 2007

Why not 4 Rolls Royce Crecy.

FLYBOYJ · Jul 21, 2007

johnbr said:
Why not 4 Rolls Royce Crecy.

They did 4 allisons and even 5 engines on a B-17.

or how about a single engine B-17?

evangilder · Jul 21, 2007

That single engined B-17 looks like a giant fighter!

Graeme · Jul 21, 2007

Got a story to tell with the single engined B-17? Have never seen it before.

This must be the Japanese copy!?
The Gasuden Koken

Maharg · Aug 3, 2007

Amazing I had never seen a single engine B-17 before. like Graeme said is there any more info on this prototype?

Graeme · Aug 3, 2007

Maharg said:
Amazing I had never seen a single engine B-17 before. like Graeme said is there any more info on this prototype?

This is all I could find Maharg. From this site, utilising the registration number on the wing.

You just landed at AeroFiles!

JB-17G 1945 = Civil and USAF test-bed for an added 6000hp P&W XT34 "Turbo-Wasp," Wright XT-35, Wright R-3350, and Allison T-56 POP: 3 [N5111N, 44-85747, x]. While results were encouraging?the Turbo-Wasp alone produced more power than the combined four wing engines and more economically?the armistice and dawn of the jet age curbed the project.

This image is also titled JB-17G, number 44-85813, with a Wright XT35 Typhoon turboprop-originally known as EB-17G.

SoD Stitch · Aug 3, 2007

Tham said:
Then again, production constraints during the war would have been a major factor against it.

My (limited) understanding of the WWII round-engine situation indicates that all P&W R-2800 production was reserved for the huge numbers of Hellcats, P-47's, and Corsairs ; there was no "excess" production of Double Wasps available for B-17/B-24 production. That would have meant at least doubling, if not tripling, R-2800 production (each fighter only needed one engine, the bombers needed four each). I'm not saying the US couldn't have done it if they didn't want to, but it wouldn't have been very cost-effective to have Wright stop producing an engine they're already tooled-up to produce, and start producing a totally different design.

syscom3 · Aug 3, 2007

SoD Stitch said:
My (limited) understanding of the WWII round-engine situation indicates that all P&W R-2800 production was reserved for the huge numbers of Wildcats, P-47's, Corsairs and, eventually, B-29's being produced; there was no "excess" production of Double Wasps available for B-17/B-24 production. That would have meant at least doubling, if not tripling, R-2800 production (each fighter only needed one engine, the bombers needed four each). I'm not saying the US couldn't have done it if they didn't want to, but it wouldn't have been very cost-effective to have Wright stop producing an engine they're already tooled-up to produce, and start producing a totally different design.

Hellcats got the -2800, not Wildcats.

B29's and B32's got the Wright R3350, and never were considered for -2800's.

If the AAF decided to mount 2800's on the B17 and B24, then existing factories could be converted to expand production.

FLYBOYJ · Aug 3, 2007

syscom3 said:
If the AAF decided to mount 2800's on the B17 and B24, then existing factories could be converted to expand production.

The factory wasn't the problem, the redesign of the current airframe was the issue as earlier pointed out. Disruption of engineering efforts for engine upgrades on B-17s and B-24s would of been a waste of time, especially when the B-29 and B-32 were coming down the pipe...

syscom3 · Aug 3, 2007

FLYBOYJ said:
The factory wasn't the problem, the redesign of the current airframe was the issue as earlier pointed out. Disruption of engineering efforts for engine upgrades on B-17s and B-24s would of been a waste of time, especially when the B-29 and B-32 were coming down the pipe...

I know, I was just commenting that the R2800 engine program could have easily been expanded, in the unlikely event, the B17's and B24's were modified for this engine.

HoHun · Aug 3, 2007

Hi Syscom,

>B29's and B32's got the Wright R3350, and never were considered for -2800's.

Hm, do you know the reason for that? It seems that the R-3350 delivered 2200 HP take-off power in the B-29, which the R-2800 could have matched - and the R-3350 proved to be a rather troublesome engine in early B-29 development while the R-2800 apparently was a mature design at the same time. (At least, that's my impression.)

Regards,

Henning (HoHun)

FLYBOYJ · Aug 3, 2007

HoHun said:
Hi Syscom,

>B29's and B32's got the Wright R3350, and never were considered for -2800's.

Hm, do you know the reason for that? It seems that the R-3350 delivered 2200 HP take-off power in the B-29, which the R-2800 could have matched - and the R-3350 proved to be a rather troublesome engine in early B-29 development while the R-2800 apparently was a mature design at the same time. (At least, that's my impression.)

Regards,

Henning (HoHun)

The R2800 for the most part was considered a "fighter engine." Although it could of easily been used, it was decided to go with the 3350 which had the power to weight ratio suited for a multi engine aircraft. Additionally the USAAF did have a call in what engine was going to be used in their bomber. After WW2 a number of commercial aircraft used the 3350 because of this.

SoD Stitch · Aug 3, 2007

FLYBOYJ said:
The R2800 for the most part was considered a "fighter engine." Although it could of easily been used, it was decided to go with the 3350 which had the power to weight ratio suited for a multi engine aircraft. Additionally the USAAF did have a call in what engine was going to be used in their bomber. After WW2 a number of commercial aircraft used the 3350 because of this.

Am I right in saying the DC-4 and DC-5 used the 3350 (as a specific example)?

FLYBOYJ · Aug 3, 2007

Yep - Turbo Compounds....

R2800 Engines for the B-17s/B-24s ?

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