WW2 without V-1710: options for the Allies?

Guess that settles it

On topic: without V-1710, the Army might want a fighter with non-turbo R-2800, as a fall back if P-47B encounters delays?

Not unless you can introduce the Non-turbo R-2800 well over one year earlier than than it did show up.

17 R-2800 single stage engines built in 1940.
1149 6402 Allison's built in 1940.

1723 R-2800 single stage engines built in 1941.
6402 Allison's built in 1941.

10,679 (?) R-2800 single stage engines built in 1942.
14,904 Allison's built in 1942.

Of the existing engines only the R-1830 and R-1820 are available early enough to have any hope of being farmed out to other companies in time to make up even a part of the numbers needed in 1940, 41 and 42. And the decision has to be made in late 1938 or early 1939. Only about 200 Wright R-2600s had been built by Dec of 1939 and it may well require new airframes ( not the P-36/P-40 airframe) or heavily modified ones.

Thanks.
All in all - not an easy task to replace the often unloved engine.

It might have been loved a bit more if the Americans had given up on their love affair with SIX .50 cal guns.

The Americans overloaded their 1150-1500hp fighters.

Doesn't settle it for me.

I still have the designer's son's speech stating one was made to make me curious. That won't change.

But I won't make the claim as fact until I know it to be true.

Shortround6 said:

It might have been loved a bit more if the Americans had given up on their love affair with SIX .50 cal guns.

The Americans overloaded their 1150-1500hp fighters.

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Or devoted more effort to developing a better supercharger for it. I've seen conflicting (second and third hand) reports that the superchargers on the Allison engines had efficiencies up to 10% lower than comparable units from Rolls Royce. Structurally, the Allison engine was sound (probably sounder than the Merlin). Without the Allison, the P-36 could have received a lot more development effort: the R-1830 (D=48 in; weight=1250 lb; 1,050 hp) could have been replaced by the two-stage engine installed in the Wildcat. If the R-1830 engine could be brought up to the same power/piston area as the R-1820, its output would be about 25% greater than the Wright engine. Alternatively, the R-1830 could be replaced by the R-2180 Twin Hornet.

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swampyankee said:

Alternatively, the R-1830 could be replaced by the R-2180 Twin Hornet.

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The R-2180 was half a R-4360, so came after the R-4360, which came after the R-2800.

Prior to that, you could use the R-2000, which is a stretched version of the R-1830.

wuzak said:

The R-2180 was half a R-4360, so came after the R-4360, which came after the R-2800.

Prior to that, you could use the R-2000, which is a stretched version of the R-1830.

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There were two distinct R-2180s: a pre-war Twin Hornet, and a post-war Twin Wasp E. The later was not quite half an R-4360 (there were some differences in the exhaust and intake arrangements). I did specify the Twin Hornet, which was the pre-war engine.

swampyankee said:

There were two distinct R-2180s: a pre-war Twin Hornet, and a post-war Twin Wasp E. The later was not quite half an R-4360 (there were some differences in the exhaust and intake arrangements). I did specify the Twin Hornet, which was the pre-war engine.

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Sorry, didn't realise.

The R-2180 was bigger in all respects than the R-1830 - bigger diameter to go along with the extra weight, capacity and power.

Wonder why they stopped it? Maybe because they started the R-2800?

I don't believe the twin Hornet had a lot to recommend it. If it had, they would surely have built more than 30 of them.

The Twin Wasp was the reliable R-1830.

The problem with the R-2180 is that it wasn't big enough. It used cylinders the exact same size as the R-2800 which means you had the frontal area of an R-2800 ( or perhaps a bit more depending on published figures) but only 78% of the power. If the 54in diameter is correct then it had 26% more frontal area but only 19% more displacement than an R-1830. Granted cowling smooth things over a bit but the power per sq ft of frontal area doesn't look good for a 14 cylinder radial.
OK for a slow bomber or transport engine but not so good for a fighter. None of the ones built had a a two speed supercharger although a two stage supercharger was planed for one version it was not built.

The R-2000 historically came after the R-2800. The first one being completed in June of 1941 (over 2 years after the first R-2800) and 8 more in Dec of 1941 at which time P W had completed 1469 R-2800s including 6 of the two stage engines.
Now maybe you can "what if" the R-2000 into 1939 but then it would be comparable to the 1939 R-1830 with 1350hp for take off and 1100hp at 13200ft Military power at best even with a two speed supercharger.

The R-2180 Twin Hornet didn't seem much heavier than the R-2000. I don't think diameter was too much of an issue, as there were versions of the Hawk with R-1820s, which were quite a lot larger in diameter than the R-1830.

The Cyclone powered Hawks were usually a bit slower than the twin Wasp Hawks. Something like 5-15mph depending on exactly which engines were fitted as even with the same take-off rating they had different power at different altitudes.

An R-2180 powered plane would be faster than a R-1830 powered one but some of the extra power goes into the extra drag so you don't get the full increase in power for performance. Both cowling design and exhaust thrust/systems were constantly evolving at this time and just a few years can make a big difference in drag/performance using the same basic components.
read some of the articles in Flight magazine or some other period literature. They may have been wrong considering the knowledge we have now but engine and airframe designers then were almost obsessed with frontal area in regards to streamlining/drag.

AFAIK swedes made the the best fighter with R1820/R1830 that could compete with anything in 1939-42.

There are 3 things that complicate this chart/proposal.

The Swedish fighter was built to a lower load limit than US fighters and possibly British fighters. 6.5 "G"s service load I beleve instead of the American standard of "8" Gs.

The Swedish fighter had two armament set ups, one was two .50s and two .30s and the other was .four 50s, what was the performance difference between the two? ( climb more than speed)

The -86 engine in the charts weighs several hundred more pounds than the original engine and requires space/drag for inter-coolers. the -86 engine being the one used in later F4F Wildcats.
Is this chart from company data or an estimate based on the published power figures vs the drag of the original engine installation?

I've always liked the J-22 and think is an often-overlooked fighter in discussion of the war.

I've seen the analysis of the J-22 as it was but have not seen the proposed P&W R-1830 equipped version's projected numbers. Impressive for what would be a relatively low-powered fighter. Needed better guns, though.

I see in one of the aerto magazines that they are getting one flight-ready in Sweden. That will be nice to see. The landing gear looks complicated, but I've not seen anything written about it being so in real life. Perhaps it was relatively simple and only LOOKS complicated.

P-66 being a better platform for the two stage Twin Wasp, since the fuselage HMGs and their ammo could be deleted, thus providing space for engine accesories?

GregP said:

Hi Milosh,

If the ALlisons hnad not "made it." then effort would have been spent to develop amternate engine into useful production engines. I would not presume to say any particular engine would make it over the rest, but there are several candidates around.

1) Chrysler hasd the XV-2220 V-16. It was two V-8's coupled back to back, made 2,500 HP and flew in the XP-47H.

2) Continental had the IV-1430 V-12 of 1,500 HP.

3) Continental had teh V-1790 V-12. Early power was just over 700 HP and they didn;t proceed further with it.

4) Lycoming had the O-1230 flat-12 of 1,000 HP. Not sure if this could have been made into a 1,500 +HP class engine.

5) Lycoming also had the XH-2470 of 2,300 HP. This was two O-1230 engine mounted sude by side vertically driving a single gearbox.

Or they could have developed an entirely new engine to a specification.

In any case, we would have developed an American engine for our planes before adopting the Merlin unless wartime expediency had required we use Merlins. That could have been the case if the allisons had failed.

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Great thread! Sorry I'm a bit late to the party.

Short answer has already been stated many times. The US AC industry would have switched to available radials. R1820, R1830 and R2600. IMHO the 2600 would have been a very capable fighter engine, if developed in that direction.

Now for the list above - All the experimental inline engines in development in 1940.

Good list, but it is missing the only one that actually made it into production.

The FORD V1650 DOHC V-12. Someone mentioned it early on, but that was the end of discussion.

"Made it into production" Missing 4 cylinders, as a V8 tank engine. The FORD GAA.

Now I know the duty cycle of a tank engine is not the same as an AC engine. In many cases it can be worse. The GAA proved itself as an extremely rugged, reliable engine. Such that the Army chose the GAA powered M4A3 to standardize on after the war.

Back to the V-12. Ford had this engine tested, production cores completed tooling ordered by mid-late 1940.

The Ford V1650 is NOT a Merlin copy. The confusion between the V1650 and the Merlin arose because they both featured the same bore and stroke (5.4" x 6.0"), and because later in the war Ford of Britain did produce 400 Merlins per week at a factory in Urmston, England.

The Rolls Royce Merlin was a SOHC with rocker followers, whereas the Ford V-1650/GAA is a true DOHC engine with the cam lobes directly acting on mechanical buckets.

It featured Direct fuel injection as well as two stage supercharging. Yes, it used a turbocharger to achieve this. However, it was a very compact package, designed in, as a package from the start.

The Merlin's (and Alison's) spark plugs were located on exhaust side of the head just below the exhaust ports, whereas the FORD V-1650 had its plugs centrally located in the pent-roof combustion chamber, as per modern practice. (Much better for detonation control).

Finally, the Ford V-1650 featured a modern, one-piece block casting, while the Merlin (and Allison) featured a split block casting.

Initially targeted at 1500 HP, this design could have been developed to 1600-1800hp, while achieving a better BSFC figure than the Merlin or the Alison.

Best of all, it was ready for aero certification and production.

That particular engine also doesn't even make a note in the history books of engines considered for aero use.

There HAS to be a reason, but I won't speculate about it since I don't know. Since it didn't make it into aero use, maybe you know the rpm range? At what rpm was the rated power and did it alreasy have a reduction gear case in it or would thaht have needed to be designed and added?

Just curious.