Improve the YP-37

[tomo pauk]

Hi Tomo, the exhaust pipes on the P-47 do NOT go down the side of the cockpit. We happen to have one and they go down the lower third of the belly under the cockpit ... and are stainless steel. They take up part of the "lower one-third of the belly." If you doubt that, come visit and see it in person. I know where they are by virue of having secured the Dzus fasteners when required.

Indeed the exhaust pipes don't go each side of cockpit of the P-47, the exhaust pipes from my sqetch do.

Don Berlin was allowed to make one turbo P-40. It performed very well at 30,000+ feet, if you can believe the reports that have been dissiminated. I don't have one of the reports but have heard a synopsis from our P-40 pilots and they say it was a good bird that was never built.

If a bird was never built, then it did not perform well at any altitude.

I have little reason to doubt it simply because the turbo P-38's were good at altitude ... so why not another turbo Allison? Probably used the same systems but I don't really know and it didn't make production, so it is an historical footnote of no consequence.

Yep, a single engined fighter with turbo V-1710 would've come in handy back in ww2.

But I am assured it DID exist and fl quite well. There certainly was no production turbo P-40 ... but I think there was a prototype that was not proceeded with. That is from heresay around the museum from people who werre there at the time ... but I can't say for sure. I wasn't there at the time. Never saw a pic of it to date.

As wuzak said, that might be the XP-60A, the max speed claimed was 420 mph.

I think the XP-37 drawing above is quite obviously mislabeled. The part labeled "supercharger " is NOT supercharger. It is a turbocharger. The supercharger was integral within the Allison V-1710 and is located between the carburetor and the intake manifold, right behind the crankshaft-accessory case joint. The carb feeds directly into the supercharger impeller. ALL Allison V-1710's were supercharged except maybe the ones used for tanks, which didn't need supercharging because they didn't need 1,000+ HP to be effective; 750 HP was just fine. The Allisons used in PT boats were all supercharged. We have one if anyone wants a FAST boat, and all the parts are on it, ready for overhaul including the flywheel. You should find your own Vee-Drive. If we have to find it, we can, but you'll do better (it will be cheaper) if you find your own.

The marine V-1710 would indeed be a rarity. Even the marine V-3420s were rare.

 

[gjs238]

I think the XP-37 drawing above is quite obviously mislabeled. The part labeled "supercharger " is NOT supercharger. It is a turbocharger.

We run across that relatively often on this board. It seems back in the day it was common to refer to both as superchargers or blowers - some were engine driven, some exhaust driven.

 

[T Bolt]

We run across that relatively often on this board. It seems back in the day it was common to refer to both as superchargers or blowers - some were engine driven, some exhaust driven.

Agree, a turbocharger is a supercharger, it's just powered by the exhaust as apposed to a mechanical linkage to the engine.

My Dad worked on one of the YP-37s back about '42 or '43 when he was a gunnery instructor in New Mexico. They had one they used for training men to synchronize the guns to the prop. He said he was told at the time that it wasn't produced in part because there were issues with the pilots starting to black out when the plane went into tight maneuvers due to the cockpit being so far aft.

 

[GregP]

That really sounds strange to me, but I won't discount it since I don't know for sure. It seems to me that the entire aircraft experiences the same g-force, but I never studied it from the perspective of maybe thinking the after fuselage sees greater rate of change of the onset of g-load. Could be ...

If that's the case, the old Gee Bees were surely the worst racing plane ever. Yet when Delmar Benjamin was flying his around, it seemed to fly just fine even through aerobatics.

Interesting premise.

 

[T Bolt]

It might not be true, that's just what my dad was told back then. It might be something interesting for a discussion. I spent some time this afternoon searching the web but could find nothing on it. When my dad first told me this I was back in grade school and it made sense to me as I associated it with the effect you feel in the last car of a roller coaster where you seem to get whipped around a lot more, so I never really questioned it.

 

[GregP]

If you think about it, a forward-placed canopy should experience the same rate-of-change-of-g, only earlier. The center of lift wil be the pivot popint. The rearward canopy might be expected to have a slightly greater rate of change of g if it is more rearward than the forward canopy is forward. But the delta between them SHOULD be small since the distance is fairly small. Might have to actually do some calculation shere to get a feeling for it, but the premnise could be valid.

I would think that if the P-37 pilot was blacking out in the rear canopy, he'd be quite close to doing the same in a centrally-placed or forward-placed canopy, so maybe he pulled too hard. The only forward-placed canopy in WWII was the two-seat trainer version of the P-39 as far as I know, and it wasn't noted for anything in particular except being UGLY.

 

[tyrodtom]

The Mig 3 and IAR-80 also have cockpits far to the rear, just not as extreme as the P-37.

 

[Rick65]

As with all Curtis's post P-40 efforts it seems a lot like trying to polish a turd.

 

[wuzak]

As with all Curtis's post P-40 efforts it seems a lot like trying to polish a turd.

The X/YP-37 were pre P-40 projects.

 

[Matt308]

C'mon gents. Physics says that unless there is a moment arm wherein significant pitch or yaw is encountered on a consistent basis independent of the airplane path, there will be no consequential c-of-g affects that might induce blackout.

Now. I might be open to nasea affects directly related to pitch/yaw changes [see modern yaw damper technology]. I think that might be an interesting thread for discussion wherein a highly maneauvering fighter with a cockpit located abnormally forward or aft of c-of-g might be of significance.

Look forward to that discussion.

 

[Shortround6]

But trying to fix it is still like trying to make ART out of camel droppings.

Perhaps it could be done but by the time the "parts" are available (later model turbo, later model turbo controls, better inter-cooler, later model Allison (P-38G/H type?) working .50 cal wing guns, etc) it is too late. It is 1943 and P-47s are showing up like 4th generation bunnies.

You also have a plane that is heavier and has higher drag (given the same armament) than a 'normal' P-40 so it isn't as good at low altitude, and you have P38s, P-47s and Spitfires already flying high altitude with the Mustang in the works.

 

[Shortround6]

C'mon gents. Physics says that unless there is a moment arm wherein significant pitch or yaw is encountered on a consistent basis independent of the airplane path, there will be no consequential c-of-g affects that might induce blackout.

Now. I might be open to nasea affects directly related to pitch/yaw changes [see modern yaw damper technology]. I think that might be an interesting thread for discussion wherein a highly maneauvering fighter with a cockpit located abnormally forward or aft of c-of-g might be of significance.

Look forward to that discussion.

P-30s were supposed to have trouble with the rear gunner blacking out, how much of that is the nasea or effects of riding backward and/or being taken a bit more by "surprise" as the pilot does something unexpected I don't know. I haven't heard much about Defiant gunners blacking out at high rates or most dive bomber gunners. At least in much higher numbers than the pilots.

DO we really want to squash ALL the hanger tall tales????

 

[GregP]

Today we know that GLOC is caused not by g-force but by the rate of change of g-force. Essentially the derivative of the g curve.

I never looked at the difference in rate of change of g-force at distances away from the CG, but I find it hard to buy that it could be farther away than about 7 - 8 feet in the case of the XP-37, and that doesn't seem like enough of an arm to make much of a difference in the slope of the g curve ... but, as I said, I never looked into it before.

I'm unlikely to look into it just now, but maybe down the pike it could surface as being of interest.

 

[tomo pauk]

Be it as it was, the P-43 seem like vastly better platform for the turbo V-1710? The max fuel was 218 gals internally, no SS tanks?

 

[GregP]

I've always liked the P-43 and most of Seversky / Kartvelli stuff. Might be a decent candidate for a turbo V-1710, as you suggest.

Probably the ultimate evolution of the design was the Reggianne Re.2005 ... definitely has Kartvelli-ish lines and the vertical tail could have come off a Kartvelli airplane ... and it has a V-12 in it. So that might be about what it would look like except the V-12 would be upright instead of inverted, so the nose would look like a Fiat G-59, possibly.

 

[gumbyk]

Today we know that GLOC is caused not by g-force but by the rate of change of g-force. Essentially the derivative of the g curve.

Have you got a reference?

Thats contradictory to everything I've read on the subject. It is a combination of rate and ultimate G-force. For a very short period of time, you can sustain extremely high forces, but it drops as time goes on:

 

[GregP]

Don't need reference. Spent time in the US Air Force and am a private pilot who has flown aerobatics.

Yes, you can sustain a lot og g for a short time, but not if the rate of change of g is too high. Spike the rate and balck out. Simple as that, and PLENTY of refernces to it are available if you look.

But ... how about:

Department of Transport and Communications, Bureau of Air Safety Investigation: THE POSSIBILITY OF G-INDUCED LOSS OF CONSCIOUSNESS (G-LOC) DURING AEROBATICS IN A LIGHT AIRCRAFT
The assistance of Wing Commander Graeme Peel (Staff officer, Aviation Medicine)
Royal Australian Air Force in preparing this report is gratefully acknowledged.
Research Report 872-1017
February 1988

"Military research has demonstrated that sudden loss of consciousness may occur if a Gz onset rate of approximately 1G per second is sustained for more than 3 to 5 seconds. It is known that G-LOC occurs in normal people and is the normal outcome if the right circumstances prevail. The real frequency with which G-LOC occurs in aviation has only been recognised relatively recently, particularly in the case of instantaneous G-LOC."

Naturally, the particular person's g-limits also come into play, but the primary cause is excessive rate of change of g-force if the ultimate g-force is less than the sustained g tolerance. Your chart is of sustained g-tolerance level, not instantaneous g-loc.

The same phenomena hold ture in Military aircraft when the stick is yanked too hard at high speed. Think combat break when someone yells, "break right!" over the radio.