Qualities that made for a great aircraft that don't show up in performance stats.

[wuzak]

From real-world events, the people at Curtiss generally pissed off Don Berlin (designer) and weren't paying much, if any, attention to fighter developments that were going on around the world. Witness the P-46 and P-53 (nothing much). The P-60 was a good-handling fighter with very-predictably mediocre speed. There wasn't a "winner" that came from Curtiss-Wright after the P-36 / P-40 series or aircraft, including their last try at it with the XF-87 Blackhawk jet. They had the much-later IBM philosophy of thinking they were the Gold standard and their thinking was "right" and everyone should just know that.

The XP-53 was completed as the XP-60.

The XP-53 was based on a P-40 fuselage with the laminar flow wing and the Continental I-1430 engine.

With the Packard V-1650-1 entering production, the USAAC was keen to combine that engine with the laminar flow wing of teh XP-53. So Curtiss proposed to convert the 2nd XP-53 airframe to the V-1650-1 engine. This would be designated XP-60.

When it was clear the I-1430 wasn't going to be ready for some time, the XP-53 was cancelled.

As Packard was just getting into V-1650-1 production, none were available for the XP-60 to start with, so a Merlin 28 was put in its place instead.The performance was not up to expectations (387mph top speed), so the project did not reach production.

XP-60A and XP-60B were to be V-1710 powered, each with a turbocharger - the A had the GE B series and the B had a Wright turbo.

The XP-60A was built, but had problems with the engine installation (it caught fire in ground running).

The XP-60B was under construction when testing of the XP-60A proved disappointing. The XP-60B was fitted with an R-2800 and single rotation propeller and designated XP-60E. Estimated top speed was about 405mph.

The XP-60C was originally to use the Chrysler IV-2220, but was built with an R-2800 and contra-props.

The XP-60D was the XP-60 fitted with the V-1650-3. I haven't seen any performance numbers for that model.

 

[wuzak]

The US had quite a few "types" that carried their own designations even though the airframe essentially remained the same, just different engines, armament or other modifications.
The P-36 is a classic case of this: YP-37, P-40 and XP-42.
P-38: XP-49.
P-39: XFL, P-400, P-63.
P-40: XP-46, XP-53, XP-60A/B/D and YP-60E.
B-17: XB-38, YB-40 and C-108.
B-24: XB-41.
B-29: XB-39, XB-44 and B-50.

There's more, but you get the idea...

The P-39C was originally designated P-45.

 

[Ivan1GFP]

I have been reading along in this thread for a while and there seems to be a big difference in opinion as to what constitutes a "different" aircraft and what is just considered just a simple model change.
To be honest, I don't know what my own opinion is on some aircraft.

As mentioned in earlier posts:
We have the Spitfire Mk.I as compared to a Spitfire Mk.24.
The Wing is different, the Fuselage is different, the Tail is different, the Engine is different.
There are some obvious similarities in line but without knowing the history of the models in between, it is pretty hard to follow the evolution of one from the other.

The Messerschmitt 109E and earlier as compared to the 109F and subsequent models is another.
Other than basic construction techniques, many features were changed to be different enough in shape and function that if the designation had changed, I doubt anyone would have argued the point.

The Soviet Yakovlev fighters are also a good example of a family of aircraft that all share some common characteristics and shapes, but it is a bit hard to argue that the two seat heavy Yak-7 and the lightweight Yak-3 are really the same aircraft.

Some aircraft such as the Macchi C.202 and C.205 are pretty obviously the same aircraft; Some C.202 were rebuilt to C.205 standard post war (minus the troublesome retractable tail wheel). It was just a matter of swapping out Engine, Oil Coolers, and Armament.

A similar argument can be made for the Lavochkin La-5 to La-7 evolution.

The case of the wing modification of the P-47N from the P-47D/M was also mentioned.
With those two models, the rest of the aircraft was almost entirely the same, but what if we had compared the early P-47B to a P-47N?
There are still similarities, but without all the models in between, would we still come to the same conclusion that they were the same aircraft?

There was also a mention that the F6F Hellcat came from the F4F Wildcat and in that case, one has to determine what "came from" really means..
There is no doubt that the mission and environment are the same and some of the construction techniques are the same, but that seems to be just the way that Grumman built aeroplanes at the time. It would be pretty similar to saying that the P-63 came from the P-39 when the only pieces that they have in common are the doors.

So what is this all leading to?

I believe the P-40 is undoubtedly derived from the P-36 but a bit more than just a simple engine swap.
There is no argument that the prototype P-37 / P-40 were conversions of P-36 airframes.
To understand how I came to this conclusion, it helps to know how the P-40 / P-36 series is put together.
There is obviously the Engine (and Radiators and Oil Coolers) ahead of the Firewall which is the most obvious difference.
The Fuselage behind the Firewall should actually be considered as two distinct pieces.
There is an Upper Fuselage and Lower Fuselage which are joined together at a horizontal seam.
This is the Fuselage Reference Line (FRL).
The P-40 up through the P-40C actually has the same lower fuselage below the FRL as the short tail P-40D and later models.
At least with the earlier long nose P-40 and short nose P-40, they had the same kind of engine.
With the P-36 to P-40, the engine is obviously different, and there are some obvious external differences in the lower fuselage.
What is not so obvious is that the upper fuselage is also a bit different. At least it appears that way from a comparison of drawings I have been able to find, so of the three major fuselage sections, none of them are really the same. Internal arrangements of equipment also appears different.
Therefore as I see it, the P-36 and P-40 are definitely different aircraft with a common ancestry and common construction techniques and a bunch of common pieces such as the wing and tail surfaces.

- Ivan.

 

[XBe02Drvr]

I have been reading along in this thread for a while and there seems to be a big difference in opinion as to what constitutes a "different" aircraft and what is just considered just a simple model change.
To be honest, I don't know what my own opinion is on some aircraft.

To be honest, I don't know either. But I do know this discussion is beginning to sound like medieval theologians coming to blows over how many angels can dance on the head of a pin.
Cheers,
Wes

 

[Schweik]

My understanding is that though they did make an early XP-40 out of the tenth P-36, performance wasn't so great (top speed barely over 300 mph) and they ended up later on sending the design to NACA for a full workup to sort out aerodynamics before they got the speed up to what they were looking for (closer to 350 mph). So it was clearly a bit more than slapping on a new engine.

The other point though is probably more salient - with or without new name designations some aircraft designs clearly did change so much over time (Spit 1 to Spit 24 say) that it's clearly a new model. While conversely sometimes they changed a model name or number for what was still the same plane.

But it's also ultimately subjective and there is no simple way to define precisely when the change happened. I'd base it on operational and tactical capabilities as anything else. But that is just one way to look at it, the subjectivity (and the refusal of some people to acknowledge that you can slice it up different ways) is what makes the debate descend into the quasi theological, as happens so often on forums.

 

[Greyman]

For what it's worth - from the NACA report on the P-40:

Introduction.
The flying qualities of the Curtiss P-40 pursuit airplane have been investigated at the request of the Army Air Corps, Material Division. The tests were conducted at Langley Field, Virginia. Approximately 22 hours of flying time were required to complete the tests, which included measurements of static and dynamic longitudinal stability, dynamic lateral stability, sideslip characteristics, controllability, stalling characteristics, and maneuverability. The P-40 is the third pursuit airplane whose flying qualities have been measured. The former tests were made on the P-36 and the P-36A airplanes. A comparison between the results of the measurements obtained on the P-36A and on the P-40 should prove interesting, inasmuch as these airplanes are practically identical except for their engine installations.

 

[jetcal1]

For what it's worth - from the NACA report on the P-40:

Introduction.
"...........A comparison between the results of the measurements obtained on the P-36A and on the P-40 should prove interesting, inasmuch as these airplanes are practically identical except for their engine installations.

Yet how much is left of the P-36 in the XP-40Q?

 

[Schweik]

For what it's worth - from the NACA report on the P-40:

Introduction.
The flying qualities of the Curtiss P-40 pursuit airplane have been investigated at the request of the Army Air Corps, Material Division. The tests were conducted at Langley Field, Virginia. Approximately 22 hours of flying time were required to complete the tests, which included measurements of static and dynamic longitudinal stability, dynamic lateral stability, sideslip characteristics, controllability, stalling characteristics, and maneuverability. The P-40 is the third pursuit airplane whose flying qualities have been measured. The former tests were made on the P-36 and the P-36A airplanes. A comparison between the results of the measurements obtained on the P-36A and on the P-40 should prove interesting, inasmuch as these airplanes are practically identical except for their engine installations.

Identical before or after they made all the changes to get it 50 mph faster?

 

[Greyman]

The report was on P-40 No.39-160 so I'll assume after.

 

[pbehn]

As mentioned in earlier posts:
We have the Spitfire Mk.I as compared to a Spitfire Mk.24.
The Wing is different, the Fuselage is different, the Tail is different, the Engine is different.
There are some obvious similarities in line but without knowing the history of the models in between, it is pretty hard to follow the evolution of one from the other.

The Messerschmitt 109E and earlier as compared to the 109F and subsequent models is another.
Other than basic construction techniques, many features were changed to be different enough in shape and function that if the designation had changed, I doubt anyone would have argued the point.
.

With the Spitfire and 109 it is quite simple, they all look like Spitfires and 109s despite everything almost being changed, they still look very similar on the ground and in the air.. A Tempest looked like a Typhoon, but the name "Typhoon" had no kudos at all.

 

[Ivan1GFP]

With the Spitfire and 109 it is quite simple, they all look like Spitfires and 109s despite everything almost being changed, they still look very similar on the ground and in the air.. A Tempest looked like a Typhoon, but the name "Typhoon" had no kudos at all.

Hello PBehn,
I suppose they should have called them all Tornado and been done with it?

If you think about it, the P-63 looks about as close to the P-39 and in development, some of the features of the King Cobra were first tested on prototypes based on the Airacobra airframe.

We can go on with this discussion of what is the same and what is different pretty much forever but my point which XBe02Drvr and Schweik seem to recognize is that it all comes down to a matter of opinion and isn't really worth an argument.

Hello XBe02Drvr,
The Angels on the head of a pin reminds me of the discussions on philosophy from back in college. Are we in agreement that if we can get the Angels to just stand instead of dance, we can get more of them on the head of a pin?

- Ivan.

 

[michael rauls]

My understanding is that though they did make an early XP-40 out of the tenth P-36, performance wasn't so great (top speed barely over 300 mph) and they ended up later on sending the design to NACA for a full workup to sort out aerodynamics before they got the speed up to what they were looking for (closer to 350 mph). So it was clearly a bit more than slapping on a new engine.

The other point though is probably more salient - with or without new name designations some aircraft designs clearly did change so much over time (Spit 1 to Spit 24 say) that it's clearly a new model. While conversely sometimes they changed a model name or number for what was still the same plane.

But it's also ultimately subjective and there is no simple way to define precisely when the change happened. I'd base it on operational and tactical capabilities as anything else. But that is just one way to look at it, the subjectivity (and the refusal of some people to acknowledge that you can slice it up different ways) is what makes the debate descend into the quasi theological, as happens so often on forums.

I couldn't agree more. Unless one is talking the extremes( obviously a p51 is a different type than a f6f for example) there is no right or wrong here. Everyone has there own criteria for what constitutes a distinct type.
To me if the fuselage and wings are majority the same even with some modification then it is still the same plane but I certainly respect that others may have different criteria.

 

[XBe02Drvr]

The Angels on the head of a pin reminds me of the discussions on philosophy from back in college. Are we in agreement that if we can get the Angels to just stand instead of dance, we can get more of them on the head off a pin?

AHA! A fellow philosopher wannabe!
Well, to employ an analogy, do you suppose a nucleus of an atom could be induced to support more electrons if they could be coerced into sitting still instead of dancing madly about? I think not!
Cheers,
Wes

 

[XBe02Drvr]

To be honest, I don't know what my own opinion is on some aircra

But it's also ultimately subjective and there is no simple way to define precisely

To be honest, I don't know either.

I couldn't agree more. Unless one is talking the extremes( obviously a p51 is a different type than a f6f for example) there is no right or wrong here. Everyone has there own criteria for what constitutes a distinct type.

I LOVE IT! The negative wave amplitude seems to be decaying, and we seem to be drifting into congruent orbits.
Cheers,
Wes

 

[GrauGeist]

OK, so...

Should the Germans have created a new designation for the Bf109 after the Emil?
And should the Americans have redesignated the P-51 after it got the got the Merlin?
Then there was the A6M: should the IJN have created a new designation for every change made?
That would have been quite a few new types to keep rack of, since there were 10 variations from the A6M1 Type 0.

Or should we quit being rivet counters and go with the historical flow in airframe identification conventions that the Governments had in place?

None of this has a thing to do with the thread topic, either...if anyone can remember what it was.

 

[CORSNING]

.....................................................................

 

[swampyankee]

OK, so...

Should the Germans have created a new designation for the Bf109 after the Emil?
And should the Americans have redesignated the P-51 after it got the got the Merlin?
Then there was the A6M: should the IJN have created a new designation for every change made?
That would have been quite a few new types to keep rack of, since there were 10 variations from the A6M1 Type 0.

Or should we quit being rivet counters and go with the historical flow in airframe identification conventions that the Governments had in place?

None of this has a thing to do with the thread topic, either...if anyone can remember what it was.

Biology faces the same sort of issue: where's the boundary between species? Taxonomy considers dogs, wolves, and coyotes to be distinct species, but they can all interbreed with no problems. Similarly, domestic cattle and bison can interbreed, but are both considered distinct species.

The cutoff is arbitrary. In the US case, at least, it's made as much by budget hacking as by any form of consistent reasoning. Two good jet-age examples could be the USN's F9F Panther/Cougar and the USAF's F84 swept-wing vs straight-wing variants and, possibly, the F-80/T-33.

 

[Elmas]

This is a Ford Fiesta

and this is a Ford Fiesta

 

[CORSNING]

Elmas, you read my mind. I was thinking a little more dramatically though.

This is a corvette,

and this is a Corvette.

 

[CORSNING]

If you pull the old " we are talking about only five years", then it looks
more like this.

Early

Late