V-1710 supercharger development potential

[Balljoint]

I wonder if sending such proposals to individual aircraft manufactuers might have been another option for securing funding ... or at least swaing the Army for its need. Then again, I'm not sure how that sort of action would mesh with military bureaucracy at the time, or if it could have caused friction between Allison and the Army.

Were Pratt and Whitney's 2-stage supercharger developments funded in-house or NAVY supported? I seem to recall the auxiliary superchargers used on the R-1830 and R-2800 were somewhat similar in configruation to the sort eventually employed on the V-1710 (hydraulically clutched and running independently from the integral single-speed supercharger stage, including lacking any sort of intercooling -until late model R-2800s- though water injection was offered fairly early on for the 2-stage 2800s).

Bell and Curtiss lobbied against boosted engines for the P-39 and P-40. They didn't have room to accommodate them.

Wright engines at least got critical turbocharger development from NACA. Charged with a similar project for the Allison they pleaded an unworkable engine design.

Perhaps recognition of the need for a high-altitude, long-range escort came too late and was too critical to take a chance on the Allison with the Merlin in hand (pretty much).

 

[Shortround6]

A lot depends on timing.

the "high-altitude, long-range escort" simple wasn't a realistic option in 1938-39 and part of 1940. The existing engine and fuel combinations wouldn't work.

US fuel at the time was 100/100 or actually ranged from 100/98 to 100/103-4 depending on batch. British Fuel was 100/115-120 in 1940. The US speced a 100/125 fuel and a number of engines were rated/tested on it but the time 1942 came along the US and British had standardized on a 100/130 specification ( the first of several different 100/130 fuel specifications).
The TWO stage Merlin's stuffed in the first Merlin Mustangs were capable of using about 30% higher cylinder pressures than any American engine in 1939 regardless of supercharger type just due to the difference in fuel. This allowed for a 20-25% higher power output for an equivalent power plant weight.

please see some of the documents posted in: http://www.ww2aircraft.net/forum/aviation/structure-weight-data-drag-analysis-42716.html

A Mustang ,clean, used 36.4% of it's all up weight for it's powerplant (this does not include the fuel and oil tanks)

A Tomahawk used 29.1% of it's 7650lb weight for it's powerplant, another 2.0% for it's fuel tanks. (this sounds like unprotected tanks) 16.4% went for crew, fuel an oil.

By the time you get to 1943 and find out that unescorted bomber "idea" was a really bad idea it is too late to design an escort fighter from scratch ( or you get things like the Fisher P-75). The Merlin Mustang was being worked on and ordered well before the disastrous raids that convinced teh American High Command that they needed escorts.

 

[tomo pauk]

This might shed some light re. USN financing P&W to get a workable 2-stage engine to work:

 

[tomo pauk]

Bell and Curtiss lobbied against boosted engines for the P-39 and P-40. They didn't have room to accommodate them.

The XP-39E, a redesign of the P-39, flew 1st time in April 1942 with a two stage V-1710. The two stage V-1710 was installed in several XP-40Q aircraft, resulting in a good aircraft when Allies have had great aircraft already.

Wright engines at least got critical turbocharger development from NACA. Charged with a similar project for the Allison they pleaded an unworkable engine design.

Not sure towards where is pointed the last sentence. The turboed V-1710 worked okay, despite some issues, even passed the tests for 2000 HP on 150 grade fuel. The work on turbo V-1710 was stalled after early 1944, so it never got to 3200 rpm and water injection.

Perhaps recognition of the need for a high-altitude, long-range escort came too late and was too critical to take a chance on the Allison with the Merlin in hand (pretty much).

There is no doubt that it was easier to retrofit the 2-stage engine in an existing airframe than to do than to install a turbo it's accesories. BTW, the P-38 did the hi-alt LR escort, despite not being ideal in that, main shortcoming probably being low numbers available in 1943.

 

[GregP]

We may be fogetting that the Allison production runs were wholy owned by the US government. If the order is for 2500 V-1710-89/91, then that is what you must deliver by contract, not improved engines. This was not a production by a private company for public consumption or competitive sale ... it was production by item number for a government contract. Any improvements would be at company expense, and their profit was always rather marginal as a result of close government oversight.

When they delivered the very sad Lightnings to the British, the fact that both engines turned the same way and the turbochargers were left out was by contract, too. Allison had nothing to do with the deletion of the turbos. It was a feature of the contract with Lockheed.

Allison was fairly trapped since there were no potential customers for the V-1710 OTHER than the US Government, except by government permission. The engine was not available for private sales since there was a war on and the government dictated the sale of their own engine design.

Rolls Royce developed the Merlin on Private funds and accepted government contracts, but Rolls Royce owned the design. As a result, if they developed improved engines, they were free to offer them to the government or whomever else they wanted to. I'll grant that if they had sold some out-of-country during the war, the British governement would had the right of refusal, but such refusal would be if the customer was a hostile foreign power or the sales would impact British deliveries, not a result of the UK owning the engine design.

In the case of the V-1710, it was developed at government request, on a government contract, as an airship engine, and the design was thus wholy government owned. Anything designed at government request on government funds is owned by the government. Any private sales would go through the US Government for solicitation as well as for approval.

Had allison been a larger company, they might have done the development themselves and would not have been in the same situation. A company like Ford, had enough money to do developments on it's own and suibmit them for government consideration. Small companies were mostly not able to be really inventive on their own, and depended on development money for the interested party. If the party happened to be a non-government entity, then the design was owned by the entity paying for the design and development. Grumman might have helped fund things that went into its aircraft, and they might have technically needed government permission to sell Wildcats to, say, the British, but the design was owned by Grumman. So all the "government permission" really was amounted to saying the government did not consider the British to be a hostile foreign power to be denied permission for a sale.

It was not quite the same thing for Allison as all Allison owned was the factory and production equipment, along with some patents on aircraft bearing design and valve design. The US Government in fact MADE Allison share their bearing patents with Rolls Royce for use on the Merlin. Allison bearings lasted MUCH longer than Roll Royce bearings did ... and there was a war on in which Eruope was at stake. Allison did not share their bearing design willingly, but they were in a bind. Refusal would amount to plant closure since they were told future Allison V-1710 production was in the balance.

You will note that Rolls Royce did not share their 2-stage supercharger design with Allison, despite there being a war on. Personally, I think that would have been a fair trade, bearings for superchargers, but Allsion was not in a position to demand terms and the 2-stage supercharger was developed after the bearing design information exchange. Allison was not forced to share valve design data and didn't.

 

[tomo pauk]

...
It was not quite the same thing for Allison as all Allison owned was the factory and production equipment, along with some patents on aircraft bearing design and valve design. The US Government in fact MADE Allison share their bearing patents with Rolls Royce for use on the Merlin. Allison bearings lasted MUCH longer than Roll Royce bearings did ... and there was a war on in which Eruope was at stake. Allison did not share their bearing design willingly, but they were in a bind. Refusal would amount to plant closure since they were told future Allison V-1710 production was in the balance.

Re. bolded part - Rolls Royce acquired from Allison a license for steel backed sleeve bearings, much before the ww2 broke out, ie. they paid the money, not that Allison gave them for free. See pg. 19 of Vee's for victory. US Army can be accused for this or that mistake, but not for making Allison give out their patented thing.

You will note that Rolls Royce did not share their 2-stage supercharger design with Allison, despite there being a war on. Personally, I think that would have been a fair trade, bearings for superchargers, but Allsion was not in a position to demand terms and the 2-stage supercharger was developed after the bearing design information exchange. Allison was not forced to share valve design data and didn't.

Was the request to RR ever forwarded, if it was ever actually made? When? That 'conspiration theory' takes for granted that it was so easy to slap the Merlin's supercharger in the V-1710 and go your merry way. The theory also neglects that the V-1710 was tested with Merlin's 2-stage supercharger.
Why the US Army, or whomever, did not say: Hey, Pratt Whitney, either you will share the 2-stage supercharger design with Allison, or will be facing consequences?

 

[Shortround6]

The XP-39E, a redesign of the P-39, flew 1st time in April 1942 with a two stage V-1710. The two stage V-1710 was installed in several XP-40Q aircraft, resulting in a good aircraft when Allies have had great aircraft already.

The XP-39E was more of a prototype for the XP-63 than related to the rest of the P-39 family. It had 1ft 10in more wing span, 23 sq ft more wing area and a fuselage 1.75 ft longer. it also picked up around 1200-1300lbs of weight empty so something else was going on besides adding the 2nd stage on the supercharger.
Sometimes engine swaps are easy, and sometimes they are very hard.

 

[GregP]

Tomo, Allison acq`uired the bearing design by US Government insistence. Of course they for paid. But tyhey would never have given the license if not for government insistence.

And that's why I said the trade of supercharger for bearings never happened ... precisely because the bearing license was mandaded well before the 2-stage supercharger was operational ... so it wasn't "on the table," so to speak, at the time. You don't seriously think a US company would license a technology that was making their bearings the only game in town ... unless they HAD to, do you?

If you do, you don't understand US business.

 

[Shortround6]

P W also had some bearing technology during WW II. A lead silver alloy on steel backings, they gave the technology away to other US companies. But then P W also only charged a dollar an engine for licence fees and sometimes didn't even collect that.

 

[wuzak]

Tomo, Allison acq`uired the bearing design by US Government insistence. Of course they for paid. But tyhey would never have given the license if not for government insistence.

And that's why I said the trade of supercharger for bearings never happened ... precisely because the bearing license was mandaded well before the 2-stage supercharger was operational ... so it wasn't "on the table," so to speak, at the time. You don't seriously think a US company would license a technology that was making their bearings the only game in town ... unless they HAD to, do you?

If you do, you don't understand US business.

IIRC Rolls-Royce attempted to build the shell type bearings that Allison used, but couldn't get the materials to bond correctly. They then got the licence from Allison. This was in the late 1920s/early 1930s. Probably about the time the Rolls-Royce R was extruding bearings, requiring a change to a master and slave rod arrangement (1931). I have little doubt that the Merlin used shell type bearings from the beginning.

Licencing their product would have made sense for Allison. It meant they didn't have to expand their facilities to make the extra bearings. For each bearing Rolls-Royce made Allison got paid - with no expenditure of their own.

Other US companies licensed products too. Wright licensed products to Russia and Germany, maybe Japan too. So it wasn't unheard of.

 

[wuzak]

You will note that Rolls Royce did not share their 2-stage supercharger design with Allison, despite there being a war on. Personally, I think that would have been a fair trade, bearings for superchargers, but Allsion was not in a position to demand terms and the 2-stage supercharger was developed after the bearing design information exchange. Allison was not forced to share valve design data and didn't.

They also didn't share it with Napiers or Bristol.

I'm sure that Hooker was published on the design of superchargers at the time, so that info was out there.

I also doubt that Allison requested the 2 stage technology. Though, as Tomo noted, Allison did test a two stage supercharger from a Merlin on the V-1710, though it was late in the war.

 

[wuzak]

Sorry to go off topic for a minute but does anyone know why these engines weren't dohc? Was it cost or that the increase in power didn't significantly make up for the extra weight or, being bulkier, the loss in aerodynamics?

It was for compactness.

The Allison V-1710 in cross section

The cam on the Allison was underneath the rockers.

On the Merlin the cam was above, but the central location reduced the frontal area by a small amount.
http://upload.wikimedia.org/wikipedia/commons/1/1e/MerlinHead.JPG

 

[wuzak]

So the turbo was deleted from the P-39 and was never offered to Don Berlin for the P-40.

The turbo was deleted from the P-39 because it was unreliable and the installation appalling.

Don Berlin designed the XP-37 and YP-37, which were turbo V-1710 powered versions of the P-36. The reliability of the turbos was, again, poor and the installation didn't make for a practical combat aircraft (rearward cockpit location).

The P-40 was designed specifically to not use a turbo. It may have even been Don Berlin himself who begged for the turbo to be dropped an an altitude rated (rather than sea level rated) V-1710 to be developed.

Then they withheld the turbos from all the fighters but the P-38. It had some issues at the start, but they were worked out within about 6 months here in the U.S.A. ... it took about another three months to work them out in Europe because we didn't know how much different European fuel was from US fuel. When we found out, they could then replicate the problem on the test stand and they figured it out.

The "European fuel" furphy again?

There were turbocharger issues long before the "fuel issues". This was not directly related to the engine, but was due to issues with the turbos themselves. At high altitudes teh wastegate controls would freeze, causing the turbo to overspeed and explode. This required GE to redesign the wastegate controls as well. This issue was certainly around in 1942, and probably persisted into 1943.

The "fuel issue" was in late 1943, Allison searching for a solution before the engines came into contact with "European fuel".

 

[GregP]

The installation may HAVE been heavy, problematic, and appaling, but it was deleted because the War Marriel baords disapproved all turbochargers for US fighters except for the P-38 and P-47. They were saved for the heavy bombers because it was anticipated that Europe would require bombing from high altitude, and turbocharger production was low relative to aircraft and engine production. The P-63 used a 2-stage Allison with the Aux-stage blower.

Don Berlin WANTED a turbocharger for the P-40, but it was denied, and he designed the P-40 without one,

There are STILL rumors he was allowed to build ONE turbocharged P-40, and I have heard his son say it, but I have no proof of its existence, so it remains a rumor.

As for the doible overhead cam, ther is no need at all for one if you are already operating 4 valves per cylinder from a single overhead cam. The guys using DOHC couldn't figure out a way to use SOHC, or they WOULD have. SOHC is cheaper and more reliable. I can't say which has the better potential, but SOHC works VERY well in the V-1710.

 

[wuzak]

The installation may HAVE been heavy, problematic, and appaling, but it was deleted because the War Marriel baords disapproved all turbochargers for US fighters except for the P-38 and P-47. They were saved for the heavy bombers because it was anticipated that Europe would require bombing from high altitude, and turbocharger production was low relative to aircraft and engine production. The P-63 used a 2-stage Allison with the Aux-stage blower.

The P-39 lost its turbo after aerodynamic tests by NACA.

The P-63 was a larger aircraft and came several years later.

Don Berlin NEVER WANTED a turbocharger for the P-40, but it was denied, and he designed the P-40 without one,

There, fixed that for you.

I can't be certain, as I am away from my references, but it was either Don Berlin or the War Material board that asked for a P-36 with V-1710 and no turbo.

Don Berlin had experience with turbos with the XP-37 and YP-37. That experience wasn't at all good. So why would he want one for the P-40?

In any case, no matter who started the process, the P-40 was specified to be a P-36 airframe with altitude rated V-1710 without turbo.

There are STILL rumors he was allowed to build ONE turbocharged P-40, and I have heard his son say it, but I have no proof of its existence, so it remains a rumor.

Mainly we hear these rumours from you Greg.

Curtiss built the P-60A with a V-1710 and turbo. It was deemed a fire hazard, so they had to do the installation again. Not sure that a P-40 with turbo years earlier would have been any good anyway.

As for the double overhead cam, there is no need at all for one if you are already operating 4 valves per cylinder from a single overhead cam. The guys using DOHC couldn't figure out a way to use SOHC, or they WOULD have. SOHC is cheaper and more reliable. I can't say which has the better potential, but SOHC works VERY well in the V-1710.

I don't know if SOHC is more reliable, but it certainly was more compact, at least in the case of the V-1710.

 

[kool kitty89]

Don Berlin WANTED a turbocharger for the P-40, but it was denied, and he designed the P-40 without one,

There are STILL rumors he was allowed to build ONE turbocharged P-40, and I have heard his son say it, but I have no proof of its existence, so it remains a rumor.

With all the trouble the XP-37 had, I wonder how a turbocharged P-40 could have fared better. (maybe more mature turbocharger development paralleling the progress made on the P-38? ... or an earlier adoption of a liquid intercooler?)

 

[GregP]

Well Wayne,

I'll have to say we disagree on several points.

I said he wanted a turbo because of a presentation given by his son at one of our monthly events. You can take it up with him ... I couldn't care less myself, but I WILL put the info out there for someone interested enough to pursue. I'm not.

Same presentation fuels the rumor about the one turbo P-40 he was supposedly allowed to build. As I plainly stated, I have no proof it was ever built. If so, I would like to see the test data and some pictures ... at LEAST one.

EVERYONE in here knows the P-39 wind tunnel test was bad. We beat it to death some time back. That was not why it was deleted from production ... it was deleted by virtue of being denied to the program by the War Materiel Board. Had the units been available, the installation could have been made to work, even if it was heavy and not optimum for the airframe. The point would have been to get to higher altitude with fighter performance remaining, not to be optimum.

EVERYONE in here knows the P-63 was a later, bigger plane. Your point is what? I didn't say it was concurrent. I also didn't tell you who won the Miss America pageant that year. How is the fact that is was a larger aircraft and later relevant to the fact that it used a 2-stage Allison? I don't see it ... but I'm sure you'll tell me.

I think they should have bought some P-63s for combat, but history has already recorded what happened. The Soviets loved them.

 

[wuzak]

Regarding the P-40 and turbo:

Don Berlin, Chief Designerat Curtiss for the P-36 and P-37 aircraft, was frustrated by the continuing problems with the turbosupercharged Curtiss XP-37 [Models 75I ND 80i] and the lack of potential for the P-36. Given the urgency of the upcoming 1938 Pursuit Competition , he obtained from Allison an estimate for cost and performance of an "altitude" rated V-1710 for use in a P-36 derivative.

Vees for Victory, p.93.

It seems that Allison had other enquiries for "altitude" rated V-1710s,

Regarding the P-63, you were talking about the turbocharger being taken away from the P-39 and then you dropped in a reference to the P-63, which I thought was irrelevent to the point you were trying to make.

 

[GregP]

The turbo was supposed to give the P-39 good altitude performance, but was deleted by hook or by crook or the War materiel Board or whomever. The very similar but larger and later P-63 dispensed with the turbo and got good high altitude pserormance from the 2-stage Allison.

I thought that was relevant ... maybe not.

But the basic design as developed in the best P-63s would have given any other WWII psiton fighter a good run for the money. Perhaps not a jet ... but, then again, none of pistons could either, despite shooting them down in decent quantities. Most of the jet kills were ambush, landing pattern, or some jet malfunction rather than "catching" the jet when he was aware and up to speed an in combat mode.

 

[kool kitty89]

The turbo was supposed to give the P-39 good altitude eprformance, but was deleted by hook or by crook or the War materiel Board or whomever. The very similar but larger and later P-63 dispensed with the turbo and got good high altitude pserormance from the 2-stage Allison.

I thought that was relevant ... maybe not.

The P-63 seems more like a case of just being a more advanced airframe overall. It doesn't seem that unrealistic that the engines used in the P-63 series could have been fitted to variants of the P-39 itself. (though maybe some complications due to added length or change in CoG)

But the P-63 design progressed well and just made more sense as a more all-around capable design ... opposed to say Spitfire or Me-109 development forcing more and more powerful/advanced engines into developments of the same basic airframe. (and the P-39 was probably the closest thing the US ever had to a Spitfire/Me-109 class fighter ... albeit the P-63 also succeeded where the Me-209/309 and Spiteful failed in terms of timely development of a genuinely superior aircraft)

But the basic design as developed in the best P-63s would have given any other WWII psiton fighter a good run for the money. Perhaps not a jet ... but, then again, none of pistons could either, despite shooting them down in decent quantities. Most of the jet kills were ambush, landing pattern, or some jet malfunction rather than "catching" the jet when he was aware and up to speed an in combat mode.

Good enough to be a reasonable substitute for the Mustang had NA not developed that machine on their own, especially if the merlin engined P-63 project had gone though. (Mustang production started sooner and the USAAF didn't put in massive orders for the P-63, so it's hard to say how well they'd have coped with ramping up production compared to what NA managed historically)

US pilots might have continued to complain about the 37 mm cannon, but it doesn't seem unreasonable that 20 mm alternative mountings could have been substituted, or even just another .50 cal.