Conslaw
Senior Airman
I indeed misspoke. I meant to say February 1943.
Opportunities Missed
- Thread starter Akuma
- Start date
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Approximate weights for single stage two speed models
R-1820-G200 1320lbs.
R-1830-S3C4G 1500lbs.
R-2000-2SDG 1570lbs.
R-2180-A 1750lbs
R-2600-A 1950lbs.
R-2600-B 1980lbs.
R-2800-A 2270lbs.
R-2800-B 2300lbs.
V-1650-1 1525lbs +300lbs
V-1710-F4R 1350lbs + 300lbs (single speed)
Now the big boys need somewhat stronger engine mounts, larger propellers and oil coolers. These well increase the weight difference some. Perhaps 200-400lbs. To keep US stringent structural requirements will require a good deal of strengthening of the airframe. Considering how much heavy the physically smaller Fw 190 is I'd imagine it's going to be a fair bit heavier than the P-36/P-40 and a little more than the Fw 190.
I think the idea has some merit but the Seversky P-35 airframe was better suited to large radials and actually had marginally better aerodynamics. This is exactly what happened with the R-2800 powered P-44. Still it would be a better idea to start from scratch.
I don't see the AAF rationale for a R-2600 P-36 though. They got exactly what the needed in the P-40. A fighter with significantly better performance than the P-36 that can be built in numbers quickly. Even before the P-40 entered production the plan was to replace It with the '410pmh' P-46. This was changed to have the 350mph P-40D segue to the '430mph' P-53 to keep production flowing as smoothly as possible.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The P-35 was nearly identical to the P-36 in size and empty weight, both being fitted with the R-1830 series engine.
The only difference is the P-36 could fly higher and faster, and most important, had superior handling.
Admiral Beez
Major
Caproni Vizzola F.5.
At 10,000ft on1050hp at 2700rpm
P-35A 306mph
P-36A 313mph
P-36C 311mph
At 10,000ft on 900hp at 2500
AP-2 307mph
At 10,000ft on 920hp at 2500
P-36A 300mph
P-36C 298mph
The P-35A and P-36C had the same armament in the same configuration. but the P-35A had that awful semi-retractable landing gear and was barely slower. The AP-2 had flush retracting gear and a lowered canopy and it lacked armament. It's unlikely that the addition of a pair of machine guns and a more suitable canopy would not retain some speed advantage over the P-36.
The P-35's only major handling problem I am aware of was its strong tendency to ground loop. This was do in part to its amphibious floatplane origins (wing set up for a shallow landing angle) and its short fuselage gave it a fairly high AOA on a three point landing. The turbulence and excessive drag with the landing gear down didn't help the situation.
FLYBOYJ
"THE GREAT GAZOO"
Hate to rain on your parade but this is not a good comparison. First, where do you get these numbers from? Wikipedia? Flight Manuals? Company brochures? Why only pick 10,000'? How about sea level performance and compare both at their service ceilings? Wing loadings? Rate of climb?
Now in your defense I know there isn't a lot of detailed flight test data for these aircraft, especially the P-35. Here's the AAC flight test report for the P-36 made October 1940:
P-36 Flight Tests
www.wwiiaircraftperformance.org
Here's some good info from Joe Baugher's site. I always found his data quite reliable.
Seversky P-35
www.joebaugher.com
Seversky P-35A
www.joebaugher.com
Shortround6
Major General
Some of them may be from here
No idea where the Seversky figures are from.
I would note that even the manual figures don't quite line up. The engine in the P-36A made peak power (1050hp) at 2550 rpm at 6,500ft. Getting 1050hp out of it at 10,000ft at 2700rpm may call for a good amount of RAM ? Some of the pre war engines didn't have military power. Using the take-off power settings for max speed was done but sometimes the manual figures don't show that. Engine was rated at 1200hp for take off at 2700rpm.
I would note that wwiiaircraftperformance has four tests of a P-36A doing propeller tests (different blade designs) and at 10,000ft using 2550rpm it was good anywhere from 995hp to 1045hp although the speed only varied by 3mph. (low 290s)
special ed
2nd Lieutenant
- 5,661
- May 13, 2018
The landing/groundloop tendency continued with the P-43 judging from the experiences of the Louisiana National Guard with their brief time using them.
FLYBOYJ
"THE GREAT GAZOO"
Yep - that was posted
During this period Seversky was a mess. Despite showing some promising designs for the period, de Serversky made some very poor business decisions and it would not surprise me that some of the numbers advertised for the P-35 and subsequent civilian models were padded.
Yep
And again, previously posted
Shortround6
Major General
slow fingers.And again, previously posted
FLYBOYJ
"THE GREAT GAZOO"
Another thing to look at is the P-36 flight manual was publish in February, 1940. The Wright Patterson flight tests were conduced in October 1940. This almost makes me believe that the original flight manual data was put together by Curtiss.
FLYBOYJ
"THE GREAT GAZOO"
Shortround6
Major General
On the P & W engines 2500rpm is an odd number. They were usually rated at 2550rpm for max continuous except for the older ones.
Trying to track down the R-1830s used in the Seversky aircraft is a bit tricky. P & W was offering several different supercharger drive ratios and one of the Seversky prototypes had an early P & W two stage (not 2 speed but two stage) supercharger, this was a different aircraft than the prototype with the Turbo.
This is not helped by the USAF engine records not matching up to the P & W records. The USAF engine records do have a number of typo's.
If the AP-2 was using a 2 stage supercharger then things get a bit strange.
Trying to track down the R-1830s used in the Seversky aircraft is a bit tricky. P & W was offering several different supercharger drive ratios and one of the Seversky prototypes had an early P & W two stage (not 2 speed but two stage) supercharger, this was a different aircraft than the prototype with the Turbo.
This is not helped by the USAF engine records not matching up to the P & W records. The USAF engine records do have a number of typo's.
If the AP-2 was using a 2 stage supercharger then things get a bit strange.
FLYBOYJ
"THE GREAT GAZOO"
And going back to post 65, all P-36 numbers were shown at 2500, P-35 numbers numbers at 2700 RPM, IMO not a valid comparison
Shortround6
Major General
Many of the P&W engines had torque meters which is more accurate means of getting HP figures than Just rpm and boost and referring to table from a test stand. Not 100% infallible though.
What is interesting is that the AP-2 is supposed to be faster with less power, regardless of the RPM.
What is also interesting is that the P-43 was supposed to good for 325mph at 10,000ft using 1200hp.
A bit different in aerodynamics but does help fill things out a bit.
What is interesting is that the AP-2 is supposed to be faster with less power, regardless of the RPM.
What is also interesting is that the P-43 was supposed to good for 325mph at 10,000ft using 1200hp.
A bit different in aerodynamics but does help fill things out a bit.
FLYBOYJ
"THE GREAT GAZOO"
I've been trying to find a P-35 flight manual, I thought we had one on here.. It will be interesting to see what the AAC performance numbers were
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The P-35A, as delivered to the Air Corps, was fitted with the R-1830-45 and the P-43A was fitted with the R-1830-49.
The AP-2 had the R-1830-9 engine and a flush landing gear configuration.
And to be honest, I don't think I've ever seen performance figures for the P-35A at sea level.
The AP-2 had the R-1830-9 engine and a flush landing gear configuration.
And to be honest, I don't think I've ever seen performance figures for the P-35A at sea level.
FLYBOYJ
"THE GREAT GAZOO"
And now that you mention it, me neither.
Shortround6
Major General
The P-35 used an R-1830-9 engine which was an early one. Engine was rated at 2450rpm and 950hp for take off and max continuous of 810hp at 2450rpm at sea level and 850hp at 2450rpm at 8,000ft max continuous.
The engines they put in the early P-36s got new cylinder heads, barrels, better connecting rods, and new rear section with a bigger supercharger impeller which allowed for a lower gear ratio. There were a very few engines rated at 2600rpm in between but the Engines in the early P-36s mark the transition to the 2700rpm engines. R-1830-13.
Most P-36s got R-1830-17s with a few more improvements (better bearings for one). One P-36B got an R1830-23 engine with an 8:1 supercharger gear instead of the 7.15:1 but it was changed back after test.
The P-35A was later in timing being impressed/commandeered/embargoed Swedish aircraft with commercial engines that got the R1830-45 designation. These engines seem to be rated at 1050hp at 2700rpm for take-off despite data sheets saying they were rated on 100 octane fuel. At any rate, 900hp at 12,000ft, rpm is in dispute, P&W says 2700rpm, Air Force says 2550rpm.
The engines they put in the early P-36s got new cylinder heads, barrels, better connecting rods, and new rear section with a bigger supercharger impeller which allowed for a lower gear ratio. There were a very few engines rated at 2600rpm in between but the Engines in the early P-36s mark the transition to the 2700rpm engines. R-1830-13.
Most P-36s got R-1830-17s with a few more improvements (better bearings for one). One P-36B got an R1830-23 engine with an 8:1 supercharger gear instead of the 7.15:1 but it was changed back after test.
The P-35A was later in timing being impressed/commandeered/embargoed Swedish aircraft with commercial engines that got the R1830-45 designation. These engines seem to be rated at 1050hp at 2700rpm for take-off despite data sheets saying they were rated on 100 octane fuel. At any rate, 900hp at 12,000ft, rpm is in dispute, P&W says 2700rpm, Air Force says 2550rpm.
I have found plenty of errors in Baugher's work . Don't get me wrong I think his site is a damn fine site but he is not anything close to an original researcher. His work relies solely on second/third hand sources and god only knows where the data actually comes from. After all most books up through 90s were written for the casual reader and not the technical minded.
My source for P-35A data and AP-2 is Bodie's Book. I thought he listed altitude for the P-35A but I can't find it. It's possable that it was achieved on 1000hp/2800rpm at ~12,000ft Double checking the AP-2 figures are: 307mhp at 10,00ft 900hp @ 2500rmp and 34.6"Hg.
My P-36A and P-36C data comes straight from TO 01-25BC-1 dated 05/25/1940. I chose 10,000 because the was a benchmark used and the only altitude I have comparable data.
Based off of engine data from the AEHS's reference page.
From Model Designations of U.S.A.F. Aircraft Engines
R-1830-45
Military power 1050 at 9,000ft or 1000hp at 11,500ft
Rated power 900hp at 12,000ft