Elvis
Chief Master Sergeant
They could, if there was room, but there isn't any.
It would require so much of a redesign, you might as well design a whole new plane.
It would require so much of a redesign, you might as well design a whole new plane.
P-40 with Griffon engine
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Shortround6
Major General
The US was far from awash in 2 stage Allisons in any part of 1943. Production of the V-1710-93 was pretty much a trickle while they sorted out several problems related to using WEP settings. The few P-63s that got the engines were flown under restrictions until the engine passed it's type test in late 1943. First production P-63s using the engine /are built in Oct 1943, the engine passed it's type test after that.
wuzak
Captain
It certainly could be made,
but....
And, of course, not many were made.
ThomasP
Senior Master Sergeant
Hey Zipper730,
As far as I know, the V-1710 never operated at a high enough power during WWII to require a contra-rotating prop. I don't think it was operationally cleared for over ~1600 HP(?) until the G series after the war. Possibly someone else has better info?
As far as I know, the V-1710 never operated at a high enough power during WWII to require a contra-rotating prop. I don't think it was operationally cleared for over ~1600 HP(?) until the G series after the war. Possibly someone else has better info?
ThomasP
Senior Master Sergeant
Or did I misunderstand and you were talking about the Griffon?
P-39 Expert
Non-Expert
Yes feasible. Was room, P-39 engine compartment exactly the same size as P-63. The P-63 moved the water tank from behind the engine to the front behind the pilot. Then the auxiliary stage goes in where the water tank was. A/S supercharger was a little heavier than the water tank it replaced, but a four blade propeller would have been needed to absorb the extra horsepower at altitude and balance the slight extra weight aft of the engine. Would have been available from April '43 for use by the AAF. Bell was making 400 P-39s per month at this point in the war.
Probable reason this plane didn't get produced is the Soviets would have wanted it and it would have been a little too good for a potential enemy to have.
Allison made nearly 5000 -93/-117/-109 engines between April '43 and the end of the war in August '45. The "engine" was the same as any contemporary P-38 engine except for the remote reduction gear common to all "E" series engines and the carb being mounted on the auxiliary stage (-93) instead of the engine stage (P-38 engines) where it should have been all along. Only difference was the second stage for the P-38 engines was a turbo and the P-63 engines was mechanical. So the "engine" was in full production. The auxiliary stage mechanical supercharger was just a normal impeller inside a normal diffuser driven by a shaft. It had a hydraulic coupling that helped with automatically controlling the speed and power but this was the only novel feature. Same engine, new auxiliary stage. All that "extended development" (for WEP) was for water injection and pistons/rings that would be used on all Allisons and could have been tested on any contemporary Allison engine. The main reason for the extended development was the P-63 airframe wasn't ready yet. They had engines in April but no P-63 to put it into until October. Bell only completed 28 P-63 airframes the rest of 1943.
The P-51D used a V-1650-7. That said the Griffon would have been V-2240.
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wuzak
Captain
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GregP
Major
I see people saying there isn't room for a 2-stage engine in the P-40. Let's think about that for a minute.
The P-40 started out as a P-36 with a radial engine that was closely-mounted to the wing. To make the P-40, they added a new engine mount that moved the engine farther from the wing. To make room for a 2-stage engine simply requires another engine mount. There's PLENTY of room.
The mitigating factor would be CG. Adding a 2-stage engine might mean moving the wings forward from where they were mounted ... OR adding a tail extension. Moving the wings is a major design headache, but there was at least one other fighter that added a tail extension for balance. Think of the Fw 190. The D and later models added a tail extension to balance the engine. No reason at all the P-40 could not have taken advantage of that twice. They HAD a long-tail version. The P-40F had a 20-inch tail extension, leaving the horizontal tail where it was and moving the fin and rudder back by 20 inches. There's really no reason they could not have installed a 2-stage engine other than they just didn't.
It doesn't take a genius to make up a new engine mount and cowling and add a small tail extension. I've done it with an RC plane (Sweet Stick) that started out with a standard .40 engine and I added a .60 and a tuned pipe. It needed a tail extension to fly right. Flew just fine, though it was a bit less agile than with the as-designed .40 engine, but that was a matter of wing loading rather than anything else. It rolled exactly the same, but need more space to turn. Sounds like a P-40 versus the P-36, doesn't it? Most of the old P-36 pilots preferred the P-36 to the P-40, if you look into it.
I think there was room to improve the P-40 but it seems like there was little apparent effort to do it other than the P-40Q which was a bit late to save the airplane family and didn't quite go far enough in any case. Close, but no cigar.
The P-40 started out as a P-36 with a radial engine that was closely-mounted to the wing. To make the P-40, they added a new engine mount that moved the engine farther from the wing. To make room for a 2-stage engine simply requires another engine mount. There's PLENTY of room.
The mitigating factor would be CG. Adding a 2-stage engine might mean moving the wings forward from where they were mounted ... OR adding a tail extension. Moving the wings is a major design headache, but there was at least one other fighter that added a tail extension for balance. Think of the Fw 190. The D and later models added a tail extension to balance the engine. No reason at all the P-40 could not have taken advantage of that twice. They HAD a long-tail version. The P-40F had a 20-inch tail extension, leaving the horizontal tail where it was and moving the fin and rudder back by 20 inches. There's really no reason they could not have installed a 2-stage engine other than they just didn't.
It doesn't take a genius to make up a new engine mount and cowling and add a small tail extension. I've done it with an RC plane (Sweet Stick) that started out with a standard .40 engine and I added a .60 and a tuned pipe. It needed a tail extension to fly right. Flew just fine, though it was a bit less agile than with the as-designed .40 engine, but that was a matter of wing loading rather than anything else. It rolled exactly the same, but need more space to turn. Sounds like a P-40 versus the P-36, doesn't it? Most of the old P-36 pilots preferred the P-36 to the P-40, if you look into it.
I think there was room to improve the P-40 but it seems like there was little apparent effort to do it other than the P-40Q which was a bit late to save the airplane family and didn't quite go far enough in any case. Close, but no cigar.
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GregP
Major
Hi Elvis,
I understand you might disagree with the above post, but what exactly do you dislike about it? Just curious, not trying to change your opinion.
I understand you might disagree with the above post, but what exactly do you dislike about it? Just curious, not trying to change your opinion.
Elvis
Chief Master Sergeant
From what I understand, the two-stage/two-speed supercharger adds a bit of length to the engine. I just don't see enough room, even if you move the oil tank, so then you're extending the nose of the airplane. More weight and leverage against the structure holding the engine, so more bracing (both in the engine compartment and the rest of the airplane).
Adds weight and throws off the balance of the airplane.
I also read a lot of "attitude" in your post. As if you were discounting everything that had been stated prior, because none of us know what we're talking about.
Likely not your intent and I often bow to your knowledge, I just feel you could've stated your case without quite so much "smartassery".
Elvis
Adds weight and throws off the balance of the airplane.
I also read a lot of "attitude" in your post. As if you were discounting everything that had been stated prior, because none of us know what we're talking about.
Likely not your intent and I often bow to your knowledge, I just feel you could've stated your case without quite so much "smartassery".
Elvis
Shortround6
Major General
These may be a case of both sides being right.
There wasn't room for the two stage supercharger in a "normal" P-40.
There was room in the XP-40Q but that was because they extended the nose and the rear fuselage to counter act the destabilizing effect of the longer nose and perhaps as counterweight to the heavier engine and 4 bladed propeller.
There wasn't room for the two stage supercharger in a "normal" P-40.
There was room in the XP-40Q but that was because they extended the nose and the rear fuselage to counter act the destabilizing effect of the longer nose and perhaps as counterweight to the heavier engine and 4 bladed propeller.
GregP
Major
Well, I didn't intend and "smartassery" and, reading it again, I don't really see any. Of course, I know my own intent ... in the eye of the beholder, I suppose.
My point was simple. You can add two Allisons up front if you want to with the right engine mount and structure bracing. Here's one where the Soviets did just that.
https://plane-encyclopedia.com/wp-content/uploads/2019/05/S-2M-103-1.jpeg
Note there are TWO V-12 inline engines in front of the cockpit with concentric contra-props. Of course, the wing leading edges aren't in line with the instrument panel either, so it was very likely designed for two inlines to start with. I still don't think a P-40 with the 2-stage Allison would have quite been up to being a "better" airplane than what we flew in the real life, but I could be wrong. Methinks that might be a "what if" that would be hard to settled because any objections could always be addressed in a re-design. Still, it's pretty hard to come up with a P-40 upgrade that would promise to outperform a P-51D in all respects. Perhaps possible, but not an easy task, to be sure.
My point was simple. You can add two Allisons up front if you want to with the right engine mount and structure bracing. Here's one where the Soviets did just that.
https://plane-encyclopedia.com/wp-content/uploads/2019/05/S-2M-103-1.jpeg
Note there are TWO V-12 inline engines in front of the cockpit with concentric contra-props. Of course, the wing leading edges aren't in line with the instrument panel either, so it was very likely designed for two inlines to start with. I still don't think a P-40 with the 2-stage Allison would have quite been up to being a "better" airplane than what we flew in the real life, but I could be wrong. Methinks that might be a "what if" that would be hard to settled because any objections could always be addressed in a re-design. Still, it's pretty hard to come up with a P-40 upgrade that would promise to outperform a P-51D in all respects. Perhaps possible, but not an easy task, to be sure.
Shortround6
Major General
It was designed from the start as a twin engine, two seat light bomber. It was exactly 10ft longer than a long fuselage P-40,
When first tested max weight was 12,460 lb/and it carried an 880lb bomb load in an internal bay under the pilot.
Contra rotating prop is nice apart from the cost
1 No P-factor
2 No Torque Reaction
3 No Rotating Air
4 No gyroscopic precession.
5 No need to produce counter rotating versions for twin engine aircraft.
Many nasty and dangerous habits we see in aircraft such as ground looping, dropping a wing near the stall or inverting, twin engine aircraft that roll on engine failure.
There is a cost in complexity and maybe a little in weight but its a good idea. I suspect the real reason we didn't see more is that the contra propeller probably shift the CoG forward and required ballast or centre of gravity changes that had not been designed in to original aircraft.
swampyankee
Chief Master Sergeant
- 3,962
- Jun 25, 2013
wuzak
Captain
Rolls-Royce and Rotol tested contra-props on Merlin and Griffon Spitfires during the war.
Possibly the main impediment to their adoption during the war was suspect reliability.
Also, Rolls-Royce converted a Vulture for testing de Havilland and Rotol contra-props on a Hawker Tornado. Testing found it less stable than the standard version.
GregP
Major
It seems there were a number of twin V-12 aircraft around. Among them were the Arsenal VB-10:
Post-war, but not by much. Definitely developed during wwII. The Bolkhovitinov S (Sparka) is below. I don't even want to think about changing the rear engine!
It was first flown in 1940, so definitely WWII timeframe. The Latacoere Late 299A is below:
It never flew but did wind up on it's nose in test. See below. That's not even counting the Macchi-Castoldi M.C. 72 because it wasn't a military warplane:
so, the single-place, double inline wasn't exactly an unknown entity. These aircraft convince me that there was a distinct possibility for shoehorning in a 2-stage engine into the P-40 fuselage and stretching the tail to accommodate the result. Again, I'm not sure it would be worth the development effort, but the above aircraft show what can be crammed into a small space if the desire is there.
The Latecoere 299A was a bit nose-heavy, as stated above, and wound up on its nose in test, as you can see below when the Germans tested it. Sadly, it burned down in the hangar before it flew, leaving noithing to fly. Note the size of the men next to the aircraft. It is NOT a small airplane! This was a prototype and likely would have wound up as a seaplane had it been flown and adopted since Latecoere was basically a seaplane company.
Post-war, but not by much. Definitely developed during wwII. The Bolkhovitinov S (Sparka) is below. I don't even want to think about changing the rear engine!
It was first flown in 1940, so definitely WWII timeframe. The Latacoere Late 299A is below:
It never flew but did wind up on it's nose in test. See below. That's not even counting the Macchi-Castoldi M.C. 72 because it wasn't a military warplane:
so, the single-place, double inline wasn't exactly an unknown entity. These aircraft convince me that there was a distinct possibility for shoehorning in a 2-stage engine into the P-40 fuselage and stretching the tail to accommodate the result. Again, I'm not sure it would be worth the development effort, but the above aircraft show what can be crammed into a small space if the desire is there.
The Latecoere 299A was a bit nose-heavy, as stated above, and wound up on its nose in test, as you can see below when the Germans tested it. Sadly, it burned down in the hangar before it flew, leaving noithing to fly. Note the size of the men next to the aircraft. It is NOT a small airplane! This was a prototype and likely would have wound up as a seaplane had it been flown and adopted since Latecoere was basically a seaplane company.
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