could the Allison engine have done what the Rolls Royce Merlin did? (1 Viewer)

[wuzak]

5) I didn't say Merlins were hand-crafted with files in the post above. I also never said Merlins were badly built. They weren't.

When you make the statement:

There was a high degree of commonality of parts throughout the series and individual parts were produced to high degree of standardization and reliability.

It implies that other engines were not, and that the Allison was somehow special.

None of the major engines could have been produced in the numbers they were if they didn't have "a high degree of commonality of parts throughout the series and individual parts were produced to high degree of standardization and reliability."

 

[wuzak]

Not sure what your problem with me is, but it is obvious you don't want to hear anything good about an Allison engine. Too bad, They ARE good engines and run just fine.

Here is Bob Deford's experience with it. He built a Marcel Jurca kit (steel tube fuselage and wood wings). It flies very nicely. He flies over and visits Chino occasionally from Arizona.

I don't have a problem with you.

They may be good engines, but in WW2 they were largely an also ran. Relegated to aircraft that would, for the most part, be considered second tier.

 

[Shortround6]

1) GE developed the turbocharger at the request of the USAAC/USN, using government money.

I am not sure about that, GE was testing turbo superchargers at the end of WW I, not sure if they had a gov contract or not. The Gov sure ordered a number of turbo units from GE during the 20s and 30s.

The Merlin was privately developed during the Schneider cup races.

only in the most indirect manner, the races were over with England winning the cup before the Merlin ever got off paper,

You know the first Merlin (PV-12) used technology directly from the Rolls Royce Type R engine.

It may have but since the Merlin used a different bore and stroke, different cylinder spacing and a few other things it might also be fair to say it was a scaled up Kestrel, how much it really owes to either engine is subject to question as the first few PV-12/Merlins tended to bounce back and forth on construction features.

You say the XP-39 was a turd. Many in here have said that. But I have yet to see ONE shred of proof from a flight test that backs it up.

Trouble is no one can find ONE shred of proof from a flight test that proves it wasn't a turd in it's original form. No one can find the flight test (or the name of the pilot) for when it went 390mph, no one can find the documentation that it actually climbed to 20,000ft in 5 minutes.
We do know that arrangements were being made to ship it to Langley within 4 weeks of first flight.
We do know that early ground running, taxi tests and early flights were plagued with over heating.
We do know that due to a suspected drive shaft problem, for which Allison designed and built a new drive shaft, that the XP-39 was not cleared to use more than 2600rpm during the time before it was sent to Langley making any high performance flights highly unlikely.
We do know that General Arnold was making at least 6 recommendations for modifications to improve performance before the XP-39 ever got to Langley. Some were never implemented, like the suggestion to change to manually operated flaps. Another recommendation was a significant reduction in fuel capacity. Indications that the XP-39 was overweight? Which documentation does show.

this is for the XP-39 with turbo, no one is saying the later P-39s were anywhere near as bad. But the cry that Langley and the NACA ruined the Airacobra doesn't hold up. Larry Bell and his engineers had done that already, Langley and the NACA saved Bell's ass and allowed him to build a fighter that did contribute to the allied war effort.

 

[Shortround6]

I don't know what type tests in the US the Merlin passed. I suspect the Merlin did not have to complete that test because it was a Rolls-Royce design that passed UK type tests.

One of the first Packard Merlin failed to pass it's type test. The US type test was 150 hours, the British test was 100 hours, there were a few other differences. The Merlin failed betten 100 hours and 150 hours. some where there are details. While the Allison had passed a type test back in 1936/37? it was a rather different engine than the C series engine used in the Tomahawks (which actually failed multiple times before getting sorted out. Part of the problem was the test stand failed to dampen any vibration like an actual aircraft frame would), Every version had to pass either a type test or a model test, you can't make a major change (like stick the P-39 extension shaft on the front) without doing another test. Any change in engine power rating needs another test. Change crankshaft? another test, the government is not going to take Allisons word (or any other companies word) that the new crankshaft is better than the old one.
It took months to get the -93 Allison used in the P-63 through it's test.

 

[Reluctant Poster]

Who is manufacturing all these Allison's? The Allison wasn't produced in serious quantaties until 1941
Deliveries of V-1710
1939 0
1940 1149
1041 6409

As far as Allied engines go the Merlin was pretty much the only game in town for the first part of the war. If the Battle of Britain was fought with American equipment it would have been P-35s and 36s. And even P-26 s.

 

[tomo pauk]

Who is manufacturing all these Allison's? The Allison wasn't produced in serious quantaties until 1941
Deliveries of V-1710
1939 0
1940 1149
1041 6409

Allison did the manufacturing of V-1710s, with some GM-owned parts' supplies (Cadillac, for example).

As far as Allied engines go the Merlin was pretty much the only game in town for the first part of the war. If the Battle of Britain was fought with American equipment it would have been P-35s and 36s. And even P-26 s.

American 'early war' and British 'early war' were not the same thing.

 

[Reluctant Poster]

Allison did the manufacturing of V-1710s, with some GM-owned parts' supplies (Cadillac, for example).



American 'early war' and British 'early war' were not the same thing.

"Could the Allison have done what the Merlin did?" was the question. The answer is no. It could not have fought the Battle of Britain.

 

[tomo pauk]

"Could the Allison have done what the Merlin did?" was the question. The answer is no. It could not have fought the Battle of Britain.

Why resort to pulling things out of context? Here is what OP was asking, I've bolded actual questions:

Okay, here's one for the technophiles (definitely not including me). The Allison engine in it's various guises has always seemed to play second fiddle to it's famous contemporary in the land of hope and glory, the Merlin. Was there any intrinsic design feature that precluded Allison engines from powering single engine fighters over Germany at 25000 feet, of was it all just a case of the American engine being hobbled by the thinking of the time - that high altitude fighters weren't required?
To get full marks, please include an objective comparison of the beers of both countries.

Nowhere in the OP is required that V-1710 takes part in the BoB, the actual questions are about why the V-1710 was lacking the power at high altitudes etc, unlike what Merlin did.

 

[Shortround6]

And the answer is that there was nothing wrong with engine, it was the supercharger setups that were lacking. A Merlin III would have nearly useless over Germany at 25000ft in late 1943/44.

 

[Reluctant Poster]

Why resort to pulling things out of context? Here is what OP was asking, I've bolded actual questions:



Nowhere in the OP is required that V-1710 takes part in the BoB, the actual questions are about why the V-1710 was lacking the power at high altitudes etc, unlike what Merlin did.

Point taken. I should have read the original question.

 

[Reluctant Poster]

And the answer is that there was nothing wrong with engine, it was the supercharger setups that were lacking. A Merlin III would have nearly useless over Germany at 25000ft in late 1943/44.

There were more issues than the poor supercharging.
In late 1943 early 1944 the V 1710 had severe oil consumption problems at altitudes over 20,000 feet. Freeman mentions this in his books and Whitney discuses it in Vee for Victory. The problem was severe enough that the MTO command was recommending substituting V1710-55/56 for -89/91 In their F-5Bs. Whitney states that it was solved later in the year.
Improved supercharging still does not solve the excessive pressure losses and fuel distribution problems caused by the very poor intake manifold design. The "Madame Queen" intake Venturi is literally a second carburetor required to suck up the fuel that collected in the intake and reintroduce it into the airstream. This is a further cost in pressure loss. No other engine required this fix.
As pointed out by Jerry Wells in his article in the Torque Meter the single block Merlins were significantly different from the later engines. He went so far as to dub the earlier engines as Super Kestrels. He also points out the the V-1710, like the early Merlins, is not a true monoblock engine, in that the cylinder liners are not divorced from the crankcase but are subjected to the distortions from the crankcase. He believes this is a limitation on the power that could be produced by the Allison. Note that the trapped flange method of retaining the cylinder liner became the standard for high performance wet sleeve engines after WWII, with the best example being the most successful racing engine of all time the Cosworth DFV.

 

[swampyankee]

Some of the V-1710 problems were installation-related, such as many of the problems in the P-38 (this was due to the rather inane assignment of the turbocharger system to the airframe maker, not the engine maker. The same assignment of responsibility caused problems with the AGT1500 installation in the M1 Abrams 30 years later. One would think they would have learned).

 

[Shortround6]

Why was the engine have severe oil consumption? major flaw in the engine or something weird going on with the crankcase breathers?
I seem to remember something about cutting the ends of the breather tubes at a different angle solving the problem?
A certain altitude and speed combination almost acting like syphon and sucking oil laden air out of the crankcase?

The "Madame Queen" intake Venturi is literally a second carburetor required to suck up the fuel that collected in the intake and reintroduce it into the airstream. This is a further cost in pressure loss. No other engine required this fix.

There were only two allied V-12s operating at high altitudes that might require such a "fix" as the Madame Queen intake manifold. The radials used much shorter intake pipes and were either individual or paired? so such a device was not needed, Russian engines used a carburetor for every pair of cylinders so again, no long intake manifold to cause problems. Yes the Allison had a problem but you are rather over stating the case.
Problem also showed up when the Allies introduced a new fuel specification. It did two things. It allowed the use of 4.3 cc of lead per gallon instead of the previous 4.0 cc of lead (which had been changed from 3.0ccs of lead) all for 100/130 fuel. It also allowed the increased use of heavier aromatic compounds to blend the fuel than the previous specifications. This allowed for greatly increased output of 100/130 fuel from the same tonnage of crude. It also reduced the volatility of the fuel ( how well it evaporated and stayed evaporated in cool air).
Again, engines with long intake passages are going to be the most affected. Since only two stage engines used intercoolers all single stage engines had pretty hot intake mixtures and rarely ran into problems. Which leaves the Merlin and the Allison, it turns out the Merlin was not immune from this problem. In post war use on transports they ran into a cold mixture problem which was solved by reversing the coolant flow (valves were added to control this) so they actually heated the air in the "intercooler" when cruising at low power settings.
Again this problem was somewhat (but not entirely) supercharger set up dependent. The Turbo Allison being about the only V-12 where the pilot could "select" how much boost was being provided by the turbo and how much was being provided by the engine supercharger. He didn't do this directly (or even knowingly) but by selecting different RPM and throttle settings for the needed power at cruise quite different use was made of the turbo and intercooler system resulting it in a wide variation of possible intake mixture temperatures. A lot of bad "advice" was given to pilots on how to the fly the P-38 which added to the problem, advice that was was in direct contradiction to how Lockheed and Allison were saying the plane should be flown yet Allison gets the blame?
Unfortunately this system also required skilled/knowledge set up and maintenance. It seems the turbo controls were often miss rigged, causing higher than normal speeds and higher pressure/velocity at the carb leading to lean conditions. There was a hydraulic turbo control on the earlier planes with an electric control on the later ones. The early one was rather easy to adjust. the later one took a refit kit.

Again, all of this was "stuff" on the outside of the basic engine. It did greatly affect the reliability of the engine but was not an inherent defect in the basic engine or it's design.
Properly sorted out Allisons were quite capable of running at high power levels for considerable periods of time.

 

[fastmongrel]

One would think they would have learned).

Nope never going to happen

 

[Shortround6]

Some of the V-1710 problems were installation-related, such as many of the problems in the P-38 (this was due to the rather inane assignment of the turbocharger system to the airframe maker, not the engine maker. The same assignment of responsibility caused problems with the AGT1500 installation in the M1 Abrams 30 years later. One would think they would have learned).

I am not even sure how much was Lockheed's fault. Government comes along and says, "here's your engine, here's your turbos and btw here's your turbo regulator, now you fit them together and make them work".
There were at least two and possibly 3 different turbo regulator setups. 1st on sensed the back pressure in the exhaust duct near the turbine on the turbo and tried to keep that at a certain value. This design philosophy was the Army's, not Lockheed's. This was supposed to by extension (and wishful thinking) maintain a constant pressure (sea level) at the intake to the carburetor. Unfortunately it caused a number of problems, like excessive back pressure, rough running and slow (sometimes non existent) control over the intake pressure. I am not sure if the electric control was the first one to measure the intake pressure and control the exhaust wastegate accordingly or if there was an intermediate step.
The government was supplying the engines, turbos and turbo regulators for the P-43 and P-47, the B-17, the B-24 and the B-29 and other experimentals.

 

[gjs238]

... Langley and the NACA saved Bell's ass and allowed him to build a fighter that did contribute to the allied war effort.

Wonder if Bell's resources could have been better used manufacturing [fill in the blank] under license.

 

[tomo pauk]

Wonder if Bell's resources could have been better used manufacturing P-40 under license.

There you go.

 

[swampyankee]

I am not even sure how much was Lockheed's fault. Government comes along and says, "here's your engine, here's your turbos and btw here's your turbo regulator, now you fit them together and make them work".
There were at least two and possibly 3 different turbo regulator setups. 1st on sensed the back pressure in the exhaust duct near the turbine on the turbo and tried to keep that at a certain value. This design philosophy was the Army's, not Lockheed's. This was supposed to by extension (and wishful thinking) maintain a constant pressure (sea level) at the intake to the carburetor. Unfortunately it caused a number of problems, like excessive back pressure, rough running and slow (sometimes non existent) control over the intake pressure. I am not sure if the electric control was the first one to measure the intake pressure and control the exhaust wastegate accordingly or if there was an intermediate step.
The government was supplying the engines, turbos and turbo regulators for the P-43 and P-47, the B-17, the B-24 and the B-29 and other experimentals.

It's certainly a complex question to answer. My experience with military project managers (I worked in the defense industry during the Carter, Reagan, and GHW Bush administrations) was that they wildly varied in competence. Interestingly, high-profile, highly classified programs tended to be worst (find a Sikorsky engineer who worked on the X-wing program. Get [almost certainly] him a little tipsy and ask about how the program was run....). UTTAS -- the program that led to the H-60 series -- was generally considered to be the best run. The others were somewhere between. Interestingly, from when I was at Sikorsky (I was not involved, except very peripherally, with the X-wing. Thank God), the USMC was considered to have the best project offices, although I don't know how they were defining "best."

 

[Koopernic]

Some posted info is not consistent with my experience.

The early impellers were 8.25 inch, later they went to 9.5 inch, and in the G-6 and later engines they were 10.25 inch impellers. The impellers were NOT too small. The US government required Allison to use the turbosuperchagers (called turbochargers today) as the high-altitude boost system. As such, the normal supercharger impeller was supposed to handle things up to about 15,000 feet, which it did even in the 8.25 inch form.

When the War Materiel Board deleted the turbochargers from the P-39 engines to save them for the bombers (due to small US reserves of Tungsten), the high-altitude boost system required by the US government was lost and the P-39 had to make due with only the small supercharger that was supposed to have a separate high-altitude boost system. They left the turbos in the P-38 and, after the fuel and intake manifold issues were corrected, it performed just fine up to service ceiling except for a very poor cockpit heater, which left the pilots quite cold. It's tough to get hot air all the way from the engine boom to the cockpit when the OAT is well below zero degrees! Electric heaters later cured that issue. If they had turbocharged the P-40, it would have performed MUCH differently. All they had to do was add a foot or two to the fuselage and it would have fit in just fine, according to several former engineers from Curtiss who have given talks at the Planes of Fame.

I make no claims, I am just repeating what I heard here. Don't ask me for the plans ...

Allison asked the government at least twice if not three times if they should develop a 2-stage supercharger for the V-1710 and the answer was no. When you are a small engine company and your primary customer declines to pay for a development, it doesn't get developed. Pure and simple. If the government had allowed the development to proceed, it could have been in service relatively quickly.

I do not claim the Allison-developed 2-stage integral supercharger would have been as good as those of Sir Stanley Hooker, but when you aren't funded to at least try, you don't get it at all. Some boost beats the crap out of NO boost. Also, it is true that if you don't occasionally ask the impossible from your people, you damned for sure won't get it. If the USAAF wanted a 2-stage supercharger, they should have funded it and simply didn't.

The angle between the accessory case and the intake is not acute and the interface is rather smooth. I should know since I worked helping overhaul them for Joe Yancey for almost 2 years and have been inside E, F, and G engines many times for both disassembly and buildup including the accessory case interface. The E and F are exactly the same except for the nose case. The E is for remote installations and connects to a driveshaft and the F has a propeller on the shaft. The G is a different animal with different parts and has a prop on the shaft, too. The displacement is the same. The crankshaft is the same 12-counterweight crank, but the G-series rods are much stronger, the intake is different, the nosecase is different, and the supercharger and accessory case are different with a bigger carburetor.

There is NOTHING inherently wrong in the Allison design and a 2-stage supercharger would have helped a lot. But someone had to pay for development if it was to be done, and the US government elected not to be that party. Allison couldn't afford it on their own. So the government got what they asked for. Plain and simple.

The rotating main engine parts of all Allisons, including the 6-counterweight crankshafts, were all designed for 4,000 rpm but the nose case wasn't. The approved rpm was 3,000 for almost all Allisons until the 12-counterweight crankshafts came out, at which time the approved rpm was raised to 3,200. The pilot had a "blip switch" and each blip would increase or decrease by 200 rpm. If you were in a dogfight and needed extra power, blip-blip and it was there. The crew chief might not like it, but you could DO it.

The approved MAP might have been 57 inches depending on model, but we have talked with a LOT of WWII pilots who said they sometimes used 3,400 rpm and 70 – 75 inches when they needed it. One was retired General Davey Allison (no relation) who demonstrated the P-40 to Claire Chenault. He said that he regularly used 70 inches in demos and never had an issue doing so. He was renowned for "getting the most from a P-40." Of course, he didn't have to work on his engines … and his crew chiefs might have hated his guts and probably did … I don't know for sure.

Joe has engines out there with 1,300+ hours on them and are still running fine with normal maintenance after 15+ years. I don't know of any Merlins doing the same and don't really expect it either since that is a long time for a high-strung WWII V-12.

I think the Merlin is a great engine. The Allison is somewhat maligned for no good reason. It did what it was designed and specified to do. The fact that the government didn't want to fund a 2-stage supercharger was a mistake. Allison did the next best thing and designed an auxiliary-stage supercharger that could be connected to the standard Allison (with a modified accessory case) to make a defacto 2-stage, although the aux stage was hydraulically driven and thus did not have a dogtooth altitude performance chart ... it was smooth. It was MUCH cheaper to design that than an entire new accessory case. The modified acdessory case had a hole drilled in it for the shaft to connect and a seal to be oil tight.

They SHOULD have been funded to develop a 2-satge integral unit ... but weren't. Ah well. Today nobody uses the Allison OR the Merlin high-altitude capabilities since that would be IFR. All warbird pilots want to play figher pilot, so they stay VFR on days of severe clear and dogfight when they get the chance at low altitudes where the difference between the Allison and the Merin is almost nothing. Both camps are usually happy with their engines today ... until they have to pay for an overhaul. Then the Allison guys are happier since the cost is about half of that for a Merlin.

What was the US Government thinking in not funding a 2 stage supercharger for the V-1710? It would have been relatively risk free.

 

[swampyankee]

What was the US Government thinking in not funding a 2 stage supercharger for the V-1710? It would have been relatively risk free.

Its experts in the USAAC didn't ask them to. Somewhere in the War Department, where the civilian leadership is in direct contact with the military leadership, somebody made a decision that turbocharging was the way to go and that efforts to develop two-stage, mechanically driven superchargers were pointless. Whether this decision was made by people in uniforms, civil servants in the War Department, turbo enthusiasts in patronage positions in the Executive Branch (who seemed exclusive to the War Department, so I don't think this is any sort of top-down push from the White House), or heavily lobbied (and possibly bribed) members of the House and Senate (again, it doesn't seem to have existed in the Navy Department, so I don't think it's a push from the legislature) can only be determined by somebody spending a lot of time in archives.