WW2 without V-1710: options for the Allies?

[drgondog]

Greg - the published CD0 Is actually .0176 - my .016 was a typo dropping the "7". Having said that, here are additional references with a cross section of values for both wind tunnel and Flight Test.
1. GALCIT wind Tunnel at Cal Tech - "Wind Tunnel Test of 1/4 scale NA-73 Pursuit Airplane with and without running propeller", Guggenheim Aeronautics Library, Report # 286 September 20, 1940. An example data is at RN=1.6M, CDw=.0046 @ M= 0.14
2. Anon, "Wind Tunnel Data for XP-51B Airplane (NAA-101), North American Aviation Report -5549, October 9, 1943. At RN=1.68 @M= 0.14M, CDw=.0053 (Full scale XP-51B w/ wings clipped at GALCIT Wind Tunnel))
3. Nissan, J.M, Gadeburg, B.L., and Hamilton, W.T. "Correlation of Drag Characteristics of a Typical Pursuit Airplane Obtained from Wind Tunnel and Flight Tests" NACA Report 916, 1948 RN=15.37M, CDw=.0053 @ 0.5M

Remember Flat Plate Drag value is such only at a specific q value - ditto CDw... both expressions of the same Total Drag value at the same speed and altitude for a given surface area. The CDo is calculated after determining the CL at that speed and GW to derive the CDi, then CDo

 

[GregP]

Thanks Bill. Appreciate it.

 

[gjs238]

Drgondog, let's say that you and I will not usually agree except only once in awhile in passing and go from there.

I don't feel in the slightest overwhelmed. I still don't see, 70 years after the fact, many Merlins used in US fighters of WWII other than the P-51, unless you're hiding them somehwere in an unpublished book. So my thoughts on it are based on what what really happened and people who were there when it went down, not some contrived what-if.

Out of the 50,000+ fighters we built other than the P-51 and the derivative P/F-82, only about 2,200 Merlin-engined P-40's were powered by Merlins plus a handful of others, and that is enough to be obvious to most who take the time to look at it. I don't need any sources for it in this case either. Leave the P-51 out and find all the Merlin-engined fighters produced for US service. They are rather conspicuous by their low numbers.

It has already happened. The results are out there for all to see. I would certainly have left this alone going forward if not for the wording.

Oh, one more thing.

I see you said the drag coefficient for the P-51 was .016.

I am interested and I wonder where you found that. When I check NACA report NA-46-130, dated 2/6/46, NACA reports ACR5D04, L5A30, ACR dated 10/40, ACR 3130, Air Corps Technical report 4677, and Boeing in-house drag data I see they mostly agree on a Cdo of 0.0176.

I want to be accurate in my data files and am NOT arguing with you. I just wonder where you found 0.016, no other agenda. Maybe that value was for a specific model? If so, I have a new "lowest Cdo" candidate for the file.

I have Cdo for a few WWII fighters in a file and, to date, the lowest is the P-51D at 0.0176 and the highest is the Brewster Buffalo F2A at 0.030 (with the Bf 109E-3 next at 0.0290). Interestingly I have the Fw 190A-3 and the Spitfire IX both at the same value of 0.0220. The lowest radial-powered entry I have to date is for the P-47 at 0.0213.

The highest single-engine flat-plate drag area I have is for the F4U Corsair at 8.38 square feet and the lowest is for the P-51D at 4.10 square feet.

How many Merlin-engined P-51's were produced?
If the P-51 did not exist, how would all those Merlins have been employed?

 

[Shortround6]

There were probably multiple agreements and modifications to the agreements and licences.

The First contract, signed in Sept 1940 was for the already mentioned ( several times) 9000 engines with 1/3 going to the US although the US may have, in the end, not taken the full the 3000 V-1650-1 engines. Packard built over 26,750 single stage Merlins and in fact delivered over 400 in Oct of 1944 so obviously additional contracts had been placed.
Packard built almost 18,600 TWO stage Merlins by the end of 1944 so again, extra contracts/agreements and licences were involved. A number of these engines did got to the British in addition to the single stage engines but the two stage engine use in Mustangs had squat to do with the original contract and Merlin use.

Engine production was often planned one to two years before actual engine delivery. Even repeat contracts called for deliveries many months in future (impart because the repeat contracts were being placed well before the existing contracts were completed.) US produced TWO stage Merlins could and did go into Spitfires, Mosquitos and Lancasters and perhaps others. If projected airframe production looked like it would not need full Packard production then Packard production would have been slowed down. Allison produced about 800 fewer engines in 1944 than it did in 1943. In part because both P-39 and P-40 Production were winding down ( and P-63 production didn't fully replace P-39 production).

The US did build a truly astonishing amount of engines during WW II but even so there was a lot or resource management going on, there was only so much steel suitable for Crankshafts or valve springs, only so much material for bearings, only so much of other materials and while the US seldom ran short it meant that factories did not have an inexhaustible supply and could build as many engines as they wanted and wait for buyers. Even structural steel I beams for Plant expansion were controlled and allocated.

Somewhat back on track, when the original agreement was signed, the production Allison was the long nosed "C" version offering 1040hp for take-off and at 15,000ft, newer versions were in the works but with only a few hundred production engines delivered and those downrated until reworked betting your future on the Allison would have been very risky. However, Allison pulled it off and not only vastly increased production (1941 saw over 5 times the production of 1940) but the development AND production of new improved models before Packard could even really get into the swing of things.

 

[GregP]

My entire point was the USA didn't USE the Merlin for anything much ... a couple of thousand P-40's out of 135,000 warplanes outside of the P-51.

So, my premise that the US wasn't going to use the Merlin if the Allison was a flop seems proven to me. We didn't use them even when we NEEDED them and they were available for the use. It is NOT that the Merlin wouldn't have been a good thing ... it is all about the attitudes at the time. The British were SURE the American Merlins would be horrible, but were pleasantly surprised that they weren't. Was this a result of good British design or American assembly line know-how?

My contention is that it was a product of both. We came together at almost the precisely right time and had the precisely right results to cement a good national partnership that lasts to this day. Did it start out that way?

No.

Glad it went to the positive side of things. We probably SHOULD have used more Merlins ... but that's the way it went.

 

[GregP]

Hey gjs230,

13,708 Merlin-powered P-51's counting the two conversions from P-51A to P-51B. It was a British contract at first and was available for experimentation with engines. You didn't see Merlins in P-38's, P-39's, P-61's, P-63's, and bombers, or many otehr aircraft intended for the USA. You saw them in a few (very few) P-40's and a couple of Curtiss (made the P-40) prototypes plus maybe a few one-off prototypes.

Otherwise we stuck to American engines like the British did with British engines. The only American-designed engines they had OTHER than the in P-51's were installed in American-supplied aircraft that were sold to the British (they paid us back in full finally in 2006 - not a problem). The Germans flew only German engines except for the Gnome-Rhone radial (due to excellent stocks of them). The Japanese flew only Janapese engines, though some were Japanese versions of German engines. They didn't actually HAVE many actual German engines and had to use plans. Some were designed after receiving foreign engines, but almost all were of Japanese manufacture and Japanese modification to designs, together with foreign props, some of which were license-built Hamilton-Standard props. They paid for the license pre-war and were legally entitled to make them. Most mass-produced Japanese engines were of Japanese design and Japanese made ... very few foreign engines or designs taken in their entirety. Their aircraft were ALSO of Japanese design, but were sometimes modifications to foreign designs with weaknesses designed out.

Almost all nations did that to an extent. If someone saw a design item that was good, they USED it in general.

The Italians used German engine designs. The USA made Merlins and used some. The Germans used French radials. The Russians used Hispano-Suizas redesigned to Russian standards plus some radials that were copies of US radials together with the props and spiners. The British mostly stuck to British designs and the French mostly stuck to French designs until they fell though they DID use some US radials. After that, they made German designs under force of arms, not by choice. The Spanish made Spanish designs until they needed more than they had, and then turned to German designs until the Germans lost the war, at which time the Spanish installed a British engine into a German-designed airframe to make the Hispano Ha.1112 fighters. The Czechs made the Avias that were Jumo-powered Bf 109's.

So we mostly all helped ourselves to designs that would aid us in the war.

 

[tomo pauk]

Hi, Greg, the Soviets did used Hispano engine, but most of their Klimovs were wholesale redesigns of it. they added 2-speed supercharger starting with M-105, reinforcing the engine itself so it was better able to withstand greater boost and RPMs.
Radial engines were again redesigns of the French and US stuff, The most prominent of them, the M-82, shared with Wright Cyclone nothing but bore IIRC.
The Mikulin family of engines was drawing the genes from BMW in-lines of the interwar period, again heavily redesigned many times in the 1940s.

 

[wuzak]

13,708 Merlin-powered P-51's counting the two conversions from P-51A to P-51B. It was a British contract at first and was available for experimentation with engines. You didn't see Merlins in P-38's, P-39's, P-61's, P-63's, and bombers, or many otehr aircraft intended for the USA. You saw them in a few (very few) P-40's and a couple of Curtiss (made the P-40) prototypes plus maybe a few one-off prototypes.

I'm not sure the NAA conversion of the P-51 to Merlin power was to a British contract. Certainly by that stage there were P-51s (or A-36s) being built for the USAAF.

For that list: the P-61 was too big and heavy an aircraft for the Merlin. And it was designed around a radial.

P-39 and P-63 were designed around in-line engines, and would not have worked vey well with radials. I know there were one or two aircraft with mid mounted radials, but they tended to be rather fat.

The Merlin was considered for the P-38 at several stages: the Merlin XX when Packard production was being started, the Merlin 60-series mid war, and the Merlin 100-series late in the war. Had the P-38 flown before the V-1710 failed, I should imagine that Merlins would be very much in the frame. R-1820s and R-1830s would not have been a very good substitute, and R-2800 power would have been a new aircraft, basically.

There were other aircraft designed around in-lines - XP-49, XP-52, XP-53, XP-54, XP-55, XP-56 (ended up with a radial), XP-58, XP-59 and XP-60. These were to be powered by the V-1710, Merlin or various experimental engines - IV-1430, H-2230, V-3420. Some of those may have been candidates for US Merlin production, had the Allison not been available.

 

[Shortround6]

There is a problem with the train of logic of " they didn't, therefore they wouldn't have."

The US ordered all kinds of stuff they later canceled. OR they ordered stuff and then amended the contracts to different models, let alone change delivery dates. And sometimes companies really came through and built things well ahead of delivery dates.

Allison in late 1942 was building over 1300 engines EACH month, Packard was building about 800 Per month (2/3s to British?) and the Allisons being built in late 1942 were a far cry from the Allisons being built in the summer/fall of 1940. The late 1942 Allisons including the 1325hp for take-off -73s, and comparable models for the P-38 and P-39. With "over boosting", wither official or unofficial, these engines could reach power levels at low altitude comparable to the low altitude cropped impeller Merlins. The Allison with 1150hp at 15,000ft was just around the corner as were the 1425hp turbo Allisons.
What happened was production levels reached a point where the Merlin wasn't really needed as a "'back up" (for perspective P W in 1938 built about 8,000 engines total, of 4 basic models , the 9 cylinder Wasp Junior, the 9 cylinder Wasp, the 14 cylinder twin wasp junior and and 14 cylinder twin wasp plus limited production (samples) of a few other engines). Allison had not only competed a very large new factory (before 1942) but in 1942 was subcontracting parts out to General Motors divisions. Cadillac made the vast majority of crankshafts, connecting rods and camshafts for Allison among other things.
And the "new, improved" Allisons meant that the aircraft using them could come closer to the performance of the same plane using a Merlin XX. Balance that with the needs of the British for Merlins and it is easy to see why the e US did not make more use of Merlin Historically.
Please note that the original contract agreement was signed about 7 months before lend-lease was signed.

If Allison had been bought by Brewster in 1940 or there had been a major flaw in the design of the Allison that was not discovered until 1940 or some other thing happened then who knows???

 

[swampyankee]

Hi, Greg, the Soviets did used Hispano engine, but most of their Klimovs were wholesale redesigns of it. they added 2-speed supercharger starting with M-105, reinforcing the engine itself so it was better able to withstand greater boost and RPMs.
Radial engines were again redesigns of the French and US stuff, The most prominent of them, the M-82, shared with Wright Cyclone nothing but bore IIRC.
The Mikulin family of engines was drawing the genes from BMW in-lines of the interwar period, again heavily redesigned many times in the 1940s.

BMW started manufacturing radials under a Pratt&Whitney license; Bramo (later absorbed by BMW) under a Bristol license.

 

[Shortround6]

The Soviets first built Hispanos (M-100s) on a contract dated June 14th 1934, negotiations had started in Aug 1933. This helps explain several things including the inability of the Hispano engine to progress much beyond 1200hp without MAJOR revision. It is simply the oldest major V-12 Used in WW II.

 

[drgondog]

My number for total Mustangs - all types including those produced by Aussies is 15700 and ~14100 for Merlin including P-51H plus XP-51G/F but I could have screwed up the math. The two XP-51J were Allison 1710-119 powered.

Wuzak - you are correct. The first XP-51B were drawn from P-51A line and were a US contract NA-91. The subsequent contract charge number for the two XP51B (XP-78 ) were NA-101. I have to check more thoroughly but I believe 2300 P-51A's were removed from earlier contract starting in June 1942 to initiate the design and tooling requirements for the Merlin P-51

 

[CobberKane]

You guys are a million miles past me in dates numbers and all that jazz. From a general point of view, it's always seemed to me that the Allison engines were hard done by from existing in the shadow of the mighty Merlin. From what I have been told from better informed individuals contributing to this forum, the Allisons lack of high altitude performance was a function of supercharger technology rather than any intrinsic inferiority in the design of the engine, and I believe if was more easily mass produced and easier to maintain in front line conditions also. Open to correction on those points, though.
Re the Merlin, I believe Packard spent a lot of time and know-how on applying mass production techniques to this engine. I've read that Merlins were designed to be built by craftsmen whereas Allisons were meant to be built by high school graduates. True? Either way, I suspect the Yanks were in a position to teach the Poms a thing or two about production line assembly circa 1943.
On the other hand, once the war is won who wants a 'made in America' Rolls Royce? I think it was tried once and no-one bought them!

 

[wuzak]

Re the Merlin, I believe Packard spent a lot of time and know-how on applying mass production techniques to this engine. I've read that Merlins were designed to be built by craftsmen whereas Allisons were meant to be built by high school graduates. True? Either way, I suspect the Yanks were in a position to teach the Poms a thing or two about production line assembly circa 1943.

Ford UK was building Merlins before Packard were. And they were using production lines, not craftsmen.

 

[Milosh]

Greg, what engine would the Americans us if the V-1710 was not available?

 

[vinnye]

Further info from Wiki about Ford Merlins ;
Early in 1940 Ford of Britain was approached by Herbert Austin, who was in charge of the shadow factory plan, about the possibility of converting an abandoned factory in Trafford Park into an aircraft engine production unit. Construction of the new factory was started in May 1940 on a 118-acre (48 ha) site. During this time Ford engineers went on a fact finding mission to Derby, where their chief engineer commented to Sir Stanley Hooker that the manufacturing tolerances used by Rolls-Royce were far too wide for them. As a consequence over a year was taken up re-drafting 20,000 drawings to Ford tolerance levels.[68]

Ford's factory, which was completed in May 1941, was built in two distinct sections to limit potential bomb damage.[nb 11] At first, the factory had difficulty in attracting suitable labour, such that large numbers of women, youths and untrained men had to be taken on. Despite this the first Merlin engine came off the production line one month after the factory's completion, and the production rate was 200 Merlins per week by 1943.[28][69][nb 12] Ford's investment in machinery and the redesign resulted in the 10,000 man-hours needed to produce a Merlin dropping to 2,727 man-hours three years later, while unit cost fell from £6,540 in June 1941 to £1,180 by the war's end. In his autobiography Not much of an Engineer, Sir Stanley Hooker states: "... once the great Ford factory at Manchester started production, Merlins came out like shelling peas. The percentage of engines rejected by the Air Ministry was zero. Not one engine of the 30,400 produced was rejected ...".[70] Some 17,316 people worked at the Trafford Park plant, including 7,260 women and two resident doctors and nurses.[69] Merlin production started to run down in August 1945, and finally ceased on 23 March 1946.[71]

 

[Shortround6]

Just to be clear this was "Ford of England" and NOT "Henry of Dearborn".

Ford in America signed a deal to build P W R-2800s just about the time that Packard signed the deal for the Merlins. Ford in America went on to build 57,637 R-2800s but did NO design or development of the engine as an engine. They did do some valuable work in figuring out new and more efficient ways to make some of the parts.

How much interchange there was between Ford of England and Packard I don't know. What we DO know is that there was a pretty good degree of interchangeability between the finished engines no matter which factory they were from. In North Africa the British gave the US around 600 British engines to be broken down and used for spare parts for the P-40Fs the US was using in that Theater. The US having for some reason, decided on only 20% spare engines instead of closer to 50% which was closer to the normal allowance of the time. There are some differences between the engines but if the majority of the parts were NOT interchangeable this would have been a pretty useless move.

 

[GregP]

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.

 

[tyrodtom]

What V8 did the Chrysler XV-2220 put together to make the V-16 ?

 

[Shortround6]

Greg, what engine would the Americans us if the V-1710 was not available?

Greg, may have his own list or choices;

It is rather dependent on WHEN the Allison goes missing.

But basically the Allison was used in FIVE production aircraft during WW II. The P-38, P-39, P-40 and P-51 and P-63. The First three date from 1938, the P-51 from 1940 and the P-63 from May of 1941.

The P-39 was designed around the remote gearbox Allison ( and the Allison was designed, in part, to accommodate remote gearboxes/propeller drives) so it is the hardest to find a substitute engine for.
The P-40 is the easiest as it is nothing more than a re-engined P-36 and can be fitted with several substitute engines to a greater or lesser degree of success. Mostly lesser as the radials at this point in history have much more drag.
The P-38 may fall in between. In it's designed role of high altitude interceptor the drag of the radials may not have been as much of a handicap. But the Cyclone is the worst from a drag standpoint and had some serious problems as a fighter engine in the early part of the war. Problems are both the drag of the radials and the fact that the R-1820 and R-1830 both trailed the Allison by several hundred horsepower for most of the duration of the war.

Leaving out the radials and any of "them thar furin ingines" that leaves pretty much the two Army Hyper engines to take up the slack. I don't believe either the Liquid cooled P W or Wright engines ever even flew in a test mule, besides the timing is all wrong for the first 3 fighters. The two Hyper engines were planned to be turbo-charged so their performance without the turbos may be a little suspect. The Army may also have been a little optimistic in how much bending and flipping you can do to an engine. It can be done but not only requires new crankcases (and possibly crankshafts) but requires new oil and coolant pick up points and such. Easier than starting over but requiring a lot of time and effort for each different version/arrangement. This was part of the advantage of the Allison, it used one basic block/power section at a time and the nose (prop) gears OR front cover for extension shaft engines fit on the same block. The production lines could be switched from P-39 engines to P-38/40 engines overnight and the factory often ran the two types of engine for several weeks at a time in alternating batches depending on need.
The different Hyper engines (upright, flat, or inverted) might need different production lines or more time for change over.
I am not sure when the Army decided the Lycoming O-1230 was too small and doubled it up to make the H-2470 but it may be out of the running even if you did bend it into a 60 degree V engine. It weighed 1325-1342lbs depending on source (without turbo) and was rated at 1200hp for take-off and at 25,000ft with the turbo ( but might not have ever been tested at that altitude?) and was longer than the Allison.
The Army seemed to favor the Continental I-1430 more. They certainly planned to use it in a lot more prototypes. Including the Bell P-39E, the Curtiss XP-53, The Lockheed XP-49 (re-engined P-38?) and the MacDonald XP-57. Development slipped by several years and "airworthy" examples only became available in Nov 1942 (?), if you could call the examples the XP-49 got "airworthy". Even in late 1943 they were troublesome and rarely, if ever, gave the full "specified" power, so even if development was sped up by several years you still have a questionable engine. And in it's upright remote gear box form it was about 20 in longer than the P-39s Allison which makes a direct substitution a little difficult.

P-51 with no viable US V-12 in 1940-41?

P-63 probably wouldn't get off paper without the Allison (or shouldn't considering the sad sagas of the XP-49 and XP-67)