What happened to the Curtiss P36/Mohawk?

[yulzari]

How did the Armée de l'Air's favourite fighter of 1940 become the poorly rated P40 of later years?

 

[davebender]

30 liters. R1830 engine. 567kg dry weight. 1.22 meter diameter.
38.67 liters. Gnome-Rhône 14N engine. 620kg dry weight. 1.29 meter diameter.

The larger displacement Gnome-Rhône 14N engine might fit the P-36 airframe without too much engineering effort. Perhaps that upgrade would have taken place if France hadn't been defeated during 1940. That should keep the P-36 competitive with contemporary fighter aircraft.

 

[FLYBOYJ]

How did the Armée de l'Air's favourite fighter of 1940 become the poorly rated P40 of later years?

Poorly rated? By who? The P-40 was probably one of the most under rated fighters of WW2 along with the P-36 and Hurricane.

 

[Shortround6]

30 liters. R1830 engine. 567kg dry weight. 1.22 meter diameter.
38.67 liters. Gnome-Rhône 14N engine. 620kg dry weight. 1.29 meter diameter.

The larger displacement Gnome-Rhône 14N engine might fit the P-36 airframe without too much engineering effort. Perhaps that upgrade would have taken place if France hadn't been defeated during 1940. That should keep the P-36 competitive with contemporary fighter aircraft.

Not a chance on god's green earth of this one working out.
Pull a 1200 HP engine in order to replace with an 1100hp engine in order to keep the plane competitive???

 

[davebender]

I think the R1830 engine was maxed out at 1,200hp. The larger displacement French engine should be capable of more hp with additional development.

 

[Shortround6]

You are right, that further development was called the 14R series and the engine gained a longer crankshaft and crankcase in order to fit a center bearing on the crankshaft between the cylinder rows. The 14N had one bearing at the front and one at the rear and it's power output was limited because of crankshaft flex.
Of course the larger crankcase, crankshaft and improved cylinder finning did add several hundred pounds to the engine making your intital comparison somewhat misleading.

 

[oldcrowcv63]

Poorly rated? By who? The P-40 was probably one of the most under rated fighters of WW2 along with the P-36 and Hurricane.

Seems to me, the P-40 had just one really poor mark: The -E based upon its poor record in early, 1941-42, combat. Other marks were not perhaps as performance-handicapped and even the -E began to redeem itself somewhat, with better tactics, by about April-May, 1942. While the P-40 may not have been as associated with such major naval victories as the F4F-4, it was probably as good, if not better. As underperforming as was the F4F-4, I don't know that anyone rates it as poor (except maybe the pilots who first flew it ) It got the job done while it fought and that was until war's end I believe.

AFAIK, whatever other attributes it possessed, the P-36 had one fatal failing wrt to its continued purchase by the primary customer. In the eyes of its major USAAC user, its speed was too low, especially compared to contemporaty fighters. It was slower than the Hurricane, Spitfire, Bf-109, and although unknown at the time, the A6M. Most important, it was slower than the P-40 which followed the liquid-cooled engine path pioneered by European developers

 

[FLYBOYJ]

Seems to me, the P-40 had just one really poor mark: The -E based upon its poor record in early, 1941-42, combat.

Are we talking PTO or MTO or both? The aircraft did suffer high losses but many of those losses boiled down to tactics and pilot skill.

 

[oldcrowcv63]

Are we talking PTO or MTO or both? The aircraft did suffer high losses but many of those losses boiled down to tactics and pilot skill.

I think the -40E Kittyhawk was mainly committed to the PTO.... It would make sense to me if P-40F Warhawks with the Merlin (which were, I believe, roughly contemporary to the -40E ( production of the E begun in August 41 and F in January 42), were sent to the Med and equipped the RAF. -40Es were also exported and I suspect the RAF got some. Before August 41, I suppose essentially P-40A-C formed many of the marks appearing in RAF colors. But don't know details except that whatever mark appeared in the Eastern desert, I believed it suffered some at the hands of Luftwaffe Bf-109s.

 

[FLYBOYJ]

I believe you may be correct. JoeB may have some data on losses in the Med, in the PTO losses are well indicated in "Bloody Shambles" and they aren't as bad as many have been made to believe over the years.

 

[davebender]

larger crankcase, crankshaft and improved cylinder finning did add several hundred pounds to the engine

Wikipedia data.
2,076kg. P-36A empty weight.
2,880kg. P-40E empty weight.

Add 300 lbs to the P-36 and it will still be 1,000 lbs lighter then a P-40. So why not give it a try?

 

[oldcrowcv63]

I believe you may be correct. JoeB may have some data on losses in the Med, in the PTO losses are well indicated in "Bloody Shambles" and they aren't as bad as many have been made to believe over the years.

Got volume 1 of BS but waiting until birthday or xmas for 2 3. I've alerted my kids that the two books are on my wish list. I think Bartsch covers P-40E ops in the PI and Java well also.

Wikipedia data.
2,076kg. P-36A empty weight.
2,880kg. P-40E empty weight.

Add 300 lbs to the P-36 and it will still be 1,000 lbs lighter then a P-40. So why not give it a try?

I think there may have been an aerodynamic problem with the design of the P-36 that limited its max speed. The XP-42 was built as a streamlined upgrade to the P-36 and at about 340 mph, was slower than any mark of the P-40. The lighter P-36 had certain performance advantages over the early P-40 but I suspect it may have had more limited growth potential. It's difficult to tell for sure and seems like it could have been a path to a significant leap in performance based on the developmental progression experienced by Republic's P-35 to P-43 to P-47.

 

[davebender]

Curtiss XP-42
According to the above site the XP-42 had a max speed of 344 mph after they got the cowling/propellor/spinner combination right. That speed was achieved with 1,050 hp.

What max speed do you think it would achieve with 300 more hp?

 

[oldcrowcv63]

Curtiss XP-42
According to the above site the XP-42 had a max speed of 344 mph after they got the cowling/propellor/spinner combination right. That speed was achieved with 1,050 hp.

What max speed do you think it would achieve with 300 more hp?

I knew you or someone else would ask something like that. My answer? probably faster than 344 mph. Consider the FM-1/F4F-4 and FM-2. The additional 150 horsepower and ~ 450 lbs weight reduction of the FM-2 had relatively little effect on its maximum speed, so maybe it wouldn't have had much effect.

 

[davebender]

Even 344mph is faster then many 1942 fighter aircraft. Add 10 mph to the max speed while retaining P-36 maneuverability and I think you would have a pretty good low cost fighter aircraft.

 

[oldcrowcv63]

Even 344mph is faster then many 1942 fighter aircraft. Add 10 mph to the max speed while retaining P-36 maneuverability and I think you would have a pretty good low cost fighter aircraft.

Certainly as fast as many fighters that had been flying and fighting for the previous 3 or so years, but you are on the cusp of a generation of fighters capable of 400+ mph. The P-43, while probably not as manueverale as the P-36, was sort of in that position and evidently considered unprofitable to develop. Evidently the P-36 gave credible service for the French, Finns and Dutch (I think), so it was probably an ok fighter, but worth putting in additional development? I don't know. I know there were some serious political issues at CW that demoted them from top fighter manufacturer for the USAAF. I can't define what they were, just relate that's what I was told in 1969 when working there.

 

[Shortround6]

Wikipedia data.
2,076kg. P-36A empty weight.
2,880kg. P-40E empty weight.

Add 300 lbs to the P-36 and it will still be 1,000 lbs lighter then a P-40. So why not give it a try?

The 1946 edition of "Aircraft engines of the world" gives the Dry weight of the 14R-24 as 819kg so it is about 440lbs heavier than the 14N. it does offer 1600hp for take-off on 100/130 fuel but you would need a bigger propeller to the best advantage of the extra power.

P-36A had one .50 cal gun and one .30 cal gun which are not included in the empty weight, although mounts and ammo boxes/chutes may be. Also no armor or self sealing tanks.
For a 1941/42 fighter take the P-40E weight. take out about 1700-1800lbs for the Allison and radiators, put back in 1700-1800lbs for the Gnome-Rhone engine (depending on exact version) and then subtract what ever guns you want to take-out of the P-40E (one .50 from each wing?) and there you go. Don't forget to add in the extra drag of the radial engine though?

Doesn't sound worth it does it?

 

[davebender]

What choice does the USA have during 1940? The P-38 was problem plagued and wasn't originally designed for mass production. All you've got are the P-36, P-39 and P-40.

For France the situation is different. They already have several hundred P-36 aircraft on hand or on order from the USA and they've got the 38.67 liter Gnome-Rhône 14N engine. So if France isn't defeated during 1940 they may as well attempt to upgrade existing P-36 aircraft with a more powerful engine.

 

[Shortround6]

OK guys, The is no magic about the P-36 and P-40. the First P-40 was the tenth P-36 pulled off the production line and fitted with the Allison so 90 something percent of ALL changes occurred from the forward spar forward. There was a bigger change going from the P-40C to the P-40D than there was from the P-36 to the early P-40s through the "C" model.

a re-engined P-36A would be a cheap fighter in 1941/42 because of several factors,

No expensive armor plate
No expensive bullet proof glass
No expensive self sealing tanks
only a few expensive guns

Of course this means that while cheap it won't be very effective and it will be rather costly in the higher losses of expensive to train pilots.

 

[davebender]

No expensive armor plate
No expensive bullet proof glass
No expensive self sealing tanks

Was this typical for French fighter aircraft or only for the H75?