USN adopts V-12 engines: pros cons?
- Thread starter tomo pauk
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Shortround6
Major General
A big stumbling block to the just add money and get faster results is there was nobody in the US to spend the money on. There was no vast group of un-employed supercharger engineers. There wasn't even a small group of un-employed supercharger engineers.
You had a very small group of already employed supercharger engineers in 4 companies. GE, P&W, Wright and Allison. Until 1935 or so GE WERE the supercharger experts in the US, they supplied designs and even parts (like impellers or even complete superchargers) to P&W and Wright and Curtiss and Packard. Their superchargers just weren't very good. With 80 octane or under fuel nobody really knew it. AS the fuel got better and more boost could be used the problems started to show up. P&W was teh first to break away and started work in 1935 or so. It took them until 1938/39 to come up with the two stage supercharger in prototype form. They were still having trouble with it in 1941/42. Wright was the next to break with GE with either the supercharger on the "G" or "G-100" version of the Cyclone 9 (R-1820) or the R-2600 depending on which book you read. Allison never really bought superchargers or parts from GE but since they built parts (including impellers) for GE under sub-contract to sell to P&W and Wright they were aware of GE design practice.
The next problem was that, as Hooker discovered in England, some of the formulas used to design superchargers and found in all text books on the subject at the time had some fundamental errors. These would have been discovered with enough experiment results not matching the theory but it still takes time.
The next problem, that can be solved with money, is that to truly develop better superchargers you need to be able to blow-up engines and superchargers on test stands by pushing them to their limits which brings up the last problem. For any given grade of fuel there is a definite limit to how much boost can be used in a given engine. With the US "stuck" on 100 octane fuel with 2% or less aromatics in 1939/40 there is a limit to how much boost can be used and it is well within the capabilities of a single stage supercharger. The whole idea of the US army turbo-charger program was to "trick" the engine into believing it was at sea level when it was at 25,000ft. the turbo and inter-cooler were to supply sea level air pressure at 100 degrees Fahrenheit to the inlet of the carburetor while not exceeding sea level back pressure at the exhaust ports (the last was not quite achieved). The turbo was supposed to provide altitude performance, not boost Military power or combat power directly.
You had a very small group of already employed supercharger engineers in 4 companies. GE, P&W, Wright and Allison. Until 1935 or so GE WERE the supercharger experts in the US, they supplied designs and even parts (like impellers or even complete superchargers) to P&W and Wright and Curtiss and Packard. Their superchargers just weren't very good. With 80 octane or under fuel nobody really knew it. AS the fuel got better and more boost could be used the problems started to show up. P&W was teh first to break away and started work in 1935 or so. It took them until 1938/39 to come up with the two stage supercharger in prototype form. They were still having trouble with it in 1941/42. Wright was the next to break with GE with either the supercharger on the "G" or "G-100" version of the Cyclone 9 (R-1820) or the R-2600 depending on which book you read. Allison never really bought superchargers or parts from GE but since they built parts (including impellers) for GE under sub-contract to sell to P&W and Wright they were aware of GE design practice.
The next problem was that, as Hooker discovered in England, some of the formulas used to design superchargers and found in all text books on the subject at the time had some fundamental errors. These would have been discovered with enough experiment results not matching the theory but it still takes time.
The next problem, that can be solved with money, is that to truly develop better superchargers you need to be able to blow-up engines and superchargers on test stands by pushing them to their limits which brings up the last problem. For any given grade of fuel there is a definite limit to how much boost can be used in a given engine. With the US "stuck" on 100 octane fuel with 2% or less aromatics in 1939/40 there is a limit to how much boost can be used and it is well within the capabilities of a single stage supercharger. The whole idea of the US army turbo-charger program was to "trick" the engine into believing it was at sea level when it was at 25,000ft. the turbo and inter-cooler were to supply sea level air pressure at 100 degrees Fahrenheit to the inlet of the carburetor while not exceeding sea level back pressure at the exhaust ports (the last was not quite achieved). The turbo was supposed to provide altitude performance, not boost Military power or combat power directly.
Shortround6
Major General
Nice try but lets look at the FACTS again. the 109 started with 250-300liters for the small Jumo engine and went to 400 liters (unprotected) when it got the DB engine. Protection came soon. The P-40 started with 378 liters "normal" and 598 liters in "overload" condition but still internal fuel, unprotected. The P-40 lost fuel capacity with the introduction of protected tanks. BTW the P-40 inherited the tank system and capacities from the P-36 so I do think it is safe to say that the P-40 was intended to have longer endurance than the 109.
I see we are back to the "morphing" 109 again. Gunboats when fire power is an issue and non-gunboats when performance is the issue? the Gunboats were developed and used how far into the design process? And some how the gunboats don't suffer ANY of the problems of normal wing gun position? If the gunboats were so great why weren't they used more?
DO you have a weight break down for the P-40 and the 109 for comparison? I really love this part of the post " airframes themselves were always are very, very light, a couple of hundreds of kilograms, or a ton at worst" GEE WHIZ, a couple of hundred Kilograms (even 300 kg is 660lbs) or a ton (2000lbs short ton) seems to be quite a difference to me. The wing on a P-40 (early) was just over 1000lbs, up over 100lbs from the P-36 wing. Landing gear was around 600lbs. Fuselage was over 400lbs. Well, there is the ton and we haven't even added the tail and no, it was not figured as part of the fuselage.
Actually it stands up rather well to the facts. you cannot take guns and fuel out of an existing airframe and expect to get dramatic results because you are stuck with the size of the exiting airframe. IF, as you say, one uses "good engineering practice" and designs a smaller airframe to begin with tailored to the smaller payload, THEN you can get much more dramatic results.
The "propose built aircraft guns" for the 109 do not show up until almost the half way point in it's career. The MG 17 was a good gun but not that much lighter or more effective than the .30 cal Browning or other peoples rifle caliber machine guns. The first German engine mounted cannon, the Lb/MG 204, was heavy, slow firing, large and feed from either 20 or 100 round drums. It saw more use as a turret gun on sea planes than between the cylinder banks of engines. The next try is the MG/FF, a license built gun adopted as an interim weapon after the MG 204 fails and the MG 151 is ready? despite numerous prototypes it doesn't see much service use between the cylinder banks until the 109F-1 and there weren't many of them. So aside from a few Jumo 109s with a MG 17 through the prop hub the engine mounted gun doesn't show up until almost 5 years after the 109s first flight. It is quickly replaced by the MG 151/15 which is a good thing because a single MG/FF is hardly first class armament in the Spring of 1941. even with a pair of MG 17s above it.
You are talking about the "installation efficiency" of the DB 601/605 but you have shown no facts or figures to actually prove it was any more efficient as an installation than the Allied V-12s.
I would agree that the P-40's airframe was sub-optimal, it was a stand in fighter that was held onto to long. But that does nothing to prove that the DB engine installations were better or worse than the allied engine installations.
I see, it was absolutely NO TROUBLE for the DB engineers to come up with the 601N, 601E, 605A and the rest of the 605s from 1939/40 to 1944? The Allison needed a bit of beefing up and some changes in manufacturing techniques to go from 1150hp to around 1500hp WER ( altitude performance didn't improve) for very little weight gain. -33 engine in the P-40C went 1325lbs, -39 engine in the E went about 1310lbs and the -81 engine in the Ns went about 1350-1355lbs. How much weight did the DB 601 series gain going from the 601A to the 605A? over 100KG? we can forget the Big supercharger models. Changing from 2400rpm to 2800rpm increased the forces acting on the crankshaft by 36% but that was no trouble?
- Thread starter
- #44
If I may return to this part:
The resulting plane can use thin wing (akin to Spitfire's?), but not the laminar-flow one, since the later is not that well suited for low speeds. It can also use Fowler flaps, and/or LE slats, in order to increase lift coefficient of the wing.
I do agree that more fuel means more flexibility for the fighters. Going to, say, 170-180 gals, should not cost too much in speed, but it will in RoC, especially with initial C series of the V-1710s in 1940 to late 1941. OTOH, it should provide a more efficient CAP, with more loiter time.
BTW:
The invitation still stands
The resulting plane can use thin wing (akin to Spitfire's?), but not the laminar-flow one, since the later is not that well suited for low speeds. It can also use Fowler flaps, and/or LE slats, in order to increase lift coefficient of the wing.
I do agree that more fuel means more flexibility for the fighters. Going to, say, 170-180 gals, should not cost too much in speed, but it will in RoC, especially with initial C series of the V-1710s in 1940 to late 1941. OTOH, it should provide a more efficient CAP, with more loiter time.
BTW:
The invitation still stands
davebender
1st Lieutenant
Then start looking at foreign V12 engine designs.
Shortround6
Major General
The only one with any advantages in 1939/40 is the Merlin and that was in the works.
MikeGazdik
Senior Airman
As far as the exchange between Shortround6 and Tomo Pauk, here is where I go with this thinking. And please keep in mind I love the P-40 and love the Allison.
Swap engines. Put the Daimler Benz in the P-40 and the Allison in the Messerschmitt. I think you suddenly have a Curtiss that is a far better aircraft because it can operate at alititude and has the capacity to carry a little more fuel to feed the beast. The Messerschmitt becomes a dud. A low altitude airplane only, that would never carry the war against the British and Allies like it traditionally did, despite the shortcomings of the airframe. It would have quickly been phased out for a better design.
The engine is crucial for the fighter. That being said we all know the biggest problem with the Allison was the supercharger.
I agree, IF the U.S. Navy had decided to use the Allison, a better supercharger would have been eventually used.
Swap engines. Put the Daimler Benz in the P-40 and the Allison in the Messerschmitt. I think you suddenly have a Curtiss that is a far better aircraft because it can operate at alititude and has the capacity to carry a little more fuel to feed the beast. The Messerschmitt becomes a dud. A low altitude airplane only, that would never carry the war against the British and Allies like it traditionally did, despite the shortcomings of the airframe. It would have quickly been phased out for a better design.
The engine is crucial for the fighter. That being said we all know the biggest problem with the Allison was the supercharger.
I agree, IF the U.S. Navy had decided to use the Allison, a better supercharger would have been eventually used.
Shortround6
Major General
The problem is timing, Stick an Allison -33 in a 109E and you would be hard pressed to tell the difference. The Germans hadn't gotten the engine mounted gun to work worth a D**M for the E model so there is no loss there and the DB 601 engines before the N model didn't have enough difference in either power or altitude performance to get exited about. Once the DB 601N shows up the the Germans pull into the lead.
Allison started work on the two stage supercharger in 1938, or at least proposed the idea. Massive plant expansions and trying to build engines for the P-39 (remote gear box), P-40 (normal engine?) and the turbo models for the P-38 ( and fiddling with the V-3420) tended to slow things down. perhaps with more demand they might have done something but they did take several wrong turns as it was.
Allison started work on the two stage supercharger in 1938, or at least proposed the idea. Massive plant expansions and trying to build engines for the P-39 (remote gear box), P-40 (normal engine?) and the turbo models for the P-38 ( and fiddling with the V-3420) tended to slow things down. perhaps with more demand they might have done something but they did take several wrong turns as it was.
Shortround6
Major General
And did they fly into combat or fly ashore to land base where they fueled and armed?
Flying Army planes off carriers was done a number of times in ferry operations but the Army planes were not fully fueled and in some cases carried no ammo to lighten them up for take-off.
Shortround6
Major General
Fletcher was not an aviator and while he could "ask' for a plane to be tested the positive results of such a test are far from certain. P-40F manual calls for a take off distance of 1000ft at 8500lbs (NO center line store) with a 20mph (17kt) head wind. With a 40mph (35kt) head distance dropped to 550ft. This can be improved by removing guns, ammo and fuel but then what do you have? A four gun fighter with 1/2 the ammo of an F4F-3 and very limited endurance.
The only "comparable type" might be the Mustang.
The only "comparable type" might be the Mustang.
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It actually seems to be Nimitz and not Fletcher making the request. The other "comparable" type in North American production was the CCR built Hawker Hurricane...
mike siggins
Airman
i remeber reading the navy didnt like inline engines more parts raaidtors anti freze waterpumps hosees to go bad not enough space on board carrier
Shortround6
Major General
If the Liquid cooled engine powered aircraft had offered enough of an advantage over the aircooled fighters they may have gone for it. The Navy was spending some money on liquid cooled prototype engines before the the war. But if the available liquid cooled engines/aircraft show little advantage over what they have why add more difficulties?
The Navy needed aircraft with short take-off distances and low stalling speeds. A Hurricane II using 35 degrees of flap needs about 700ft for take-off in zero wind which is much better than a P-40 but it's performance is much closer to the Wildcats to begin with and I don't believe the Sea Hurricane ever got a folding wing?
The Navy needed aircraft with short take-off distances and low stalling speeds. A Hurricane II using 35 degrees of flap needs about 700ft for take-off in zero wind which is much better than a P-40 but it's performance is much closer to the Wildcats to begin with and I don't believe the Sea Hurricane ever got a folding wing?
No, but the USN seemed willing to accept a fixed wing (P40F) if they could get superior performance. The Hurricane II had a considerably better P/W ratio than the F4F-4 with the same wing area and it should have better TO performance than either the P-40 or F4F-4.
Yes, the Secret Years states that the Hurricane IIc had a TO distance of 235 yds at 7400lb versus 320 yds at 7800lb for the Martlet. BWOC, the Fulmar II had a 300 yd TO. (all aircraft with no wind)
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bobbysocks
Chief Master Sergeant
what about the B-25s? yes, they were lightened of armament but still a good bomb and fuel load. that is still one heavy ac for a carrier op. if you can get a 25 airborne off a carrier shouldnt you be able to get a 51 off?? i dont know if the airframe would handle a carrier landing ( hook ) though.
Shortround6
Major General
The Hurricane may have been using 35 degrees of flap, Not cheating since it could do it when ever it wanted. Not sure why the Martlet needed 320yds since a number of sources say 650-710 feet depending on F4F model.
The P-40 seems to have had a minimum flying speed 10-20mph higher than F4F depending on models of each and weight.
Special operations are one thing, day-in-day-out flying is another. A higher loss rate of planes and pilots putting up daily CAPs is not something the Navy could afford. Carriers were often down 2-4 fighter planes from full strength (or leaving harbor strength) just due to accidents in maintaining routine patrols when they did engage the enemy.
Aside from the speed the P-40 seems to have offered very little for carrier operations. Worse view from cockpit ( although no worse than a Spitfire?), No more ammo but not enough less to matter. Less fuel/endurance and to the Navy endurance was more important than actual range. Many planes spent 30 minutes or more stooging about waiting for their turn to land. Higher landing/take-off speeds.
It seems likely that the Hurricane should have an advantage in TO run, if both aircraft are measured by the same method.
