XP-39 II - The Groundhog Day Thread (3 Viewers)

[XBe02Drvr]

Hello P-39 Expert,

For the umpteenth time:
If this is really your response after all the information and explanations and evidence presented to you, either you are incapable of understanding weight and balance of aircraft or cannot comprehend how this information fits together.
You can wish whatever you want, but there were many intelligent and skilled people on the scene when YOU were not and I would trust their conclusions over yours. You clearly do not qualify as a P-39 "Expert".

- Ivan.

Send him to UPT. Hopefully that would knock some sense into him before he washes out. I would even go back on active duty if I could be his instructor in Primary. Oh, the fun we would have!

 

[PAT303]

If this is really your response after all the information and explanations and evidence presented to you, either you are incapable of understanding weight and balance of aircraft or cannot comprehend how this information fits together.

Didn't someone say this about 15 pages back, post 576, that handsome fella, from Australia I think

 

[Stig1207]

The Russians beat the Luftwaffe with the P-39, after they lightened it a little.

The 8th wasn't mighty, it was a myth. They never met a Luftwaffe aircraft over Germany; LW wrecks were strewn all over the steppes.

Did you by any chance follow the link I provided somewhere about post #700? It could give you a bit of an insight into what sought of overclaiming that was going on and how that is going to effect the P-39s combat record. The Soviets did better with the P-39 than the Americans, but not 20-fold better.

The Lutwaffe certainly didn't seem to notice that they were beaten by the P-39 on the EF.

 

[Reluctant Poster]

According to whom? After all, despite carrying the much heavier 37mm cannon and the weight of the long driveshaft, the P-39 was lighter than the P-40 models with the same engine versions. This was reflected in the P-39s higher speed, higher rate of climb and superior ceiling to equivalent P-40 models. Indeed, it's fair to suggest the Allied war effort would have been better off it Curtiss had been told to build P-39s instead of P-40s.
The Airacuda suffered due to a bad concept, but was still faster and heavier-armed than equivalent attack aircraft such as the A-18 Curtiss Shrike
The XP-77 was as unlikely as many other similar lightweight fighter designs made in France, but it still managed to reach 330mph on a 500hp engine, which was quite an engineering achievement.
The XP-59 was vastly constrained by both the restrictions of the requirement and the restrictions on information about the new jet engines given to Bell by the USAAC. They weren't given any design information on the engines other than rough external dimensions! At the same time, they were told they had to make the aircraft big enough to carry two engines, lots of fuel and be very safe for pilots unused to the new jets. The result was designed more as a trainer than a fighter. BTW, the only other operational fighter to get the same J-31 engine was the Ryan Fireball, which was actually slower than the XP-59. Bell's development of a better fighter design, the XP-59B, was transferred to Lockheed and was developed into the P-80 Shooting Star, which was far superior to contemporary prop fighters.
And how many successful fighter designs did Bell's much bigger competitor Curtiss make after the P-40? Yup, zero.

The Airacuda wasn't an attack aircraft it was supposed to be a bomber destroyer, comparisons to the A-18 are moot.

Did the XP-77 actually achieve 330 mph? The testing program was very short lived. One look at the The XP-77 with the pilot sitting so far aft makes you wonder how effective it could have been. Deflection shooting would be out of the question

The P-59A was not designed as a trainer. It was supposed to be a fighter. Due to it poor performance orders were cut back and it was relegated to the training role.
The J-31 you disparage is basically the Welland used in the Meteor MkI (Both based on the Whittle WB.2/23) which despite being heavier than the P-39A was much faster. As to the Me 262 there is no comparison.
From ch11-2
Although having about the same total thrust as the Me 262, along with a thrust-to-weight ratio over 30 percent greater than that of the German aircraft, the P-59A was slower by about 130 miles per hour. Analysis shows that the 65-percent-greater wing area and consequent greater drag area of the P-59A was responsible for much but not all of the difference in performance of the two aircraft. Perhaps the thick airfoil sections of the P-59A or some other sources of added drag contributed to its poor performance, or perhaps the engines did not perform as anticipated. An obvious question concerns the choice of so large a wing area for the aircraft. In comparison with the 60-poundper-square-foot wing loading of the Me 262, the corresponding value for the Airacomet was 28 pounds per square foot. The use of sophisticated leading-edge and trailing-edge high-lift devices on the Me 262 gave acceptable takeoff, landing, and maneuver characteristics with a small wing area and high wing loading on this aircraft. Only small, simple, inboard trailing-edge flaps were used on the P-59A, and the resultant low maximum lift coefficient no doubt played a large part in dictating the choice of a low wing loading and associated large wing area.
In any event, the poor performance of the P-59A precluded its adoption as a production fighter for the U.S. Armed Forces. The P-59 is included here only because of its historic interest as the first jet aircraft developed in the United States.

As I stated in another post Curtiss, in my opinion, was a basket case long before the end of WWII. Saying Bell was better than Curtiss is, as my uncle used to say, like beating a one legged man in an ass kicking contest. I believe he meant donkeys.

 

[Ivan1GFP]

Didn't someone say this about 15 pages back, post 576, that handsome fella, from Australia I think

Hello PAT303,

You were probably correct, but I try to give folks the benefit of the doubt.
I just don't expect to find religious fanatics when it comes to WW2 aircraft and there is a pretty good chance that is what is happening here.

The discussion wasn't a total waste. Think of all the entertainment we have gotten in the last 15 pages.

- Ivan.

 

[Reluctant Poster]

I think this point has been made before. The P-39 had a very high accident rate in the training programs in the US.

 

[fubar57]

But of course, almost all the P-39's weren't lost from uncontrollable tumbling. We know that for a fact

 

[Reluctant Poster]

I think this point has been made before. The P-39 had a very high accident rate in the training programs in the US.
View attachment 599408

I should also note that you were more likely to die in a P-39 accident that in any other fighter except for the P-38. Doing the math the fatality rate per 100,000 flying hours was 46.7 for the P-39, with the "runner up" P-38 at 33.4. The P 40 was 17.1, the P-47 was 16.8 and the P-51 was 16.7.

 

[Peter Gunn]

For god sakes, stop scaring me!!!

BOOOOOOOO!!!

BOOOOO I SAYS!!!

 

[FLYBOYJ]

P-39D was a dog at 7650lbs. Could be made competitive by losing the nose armor and the .30s. Move the radio up from the tail cone for balance. For the umpteenth time.

And for the umpteenth time, we showed you what will happen if you remove nose armor and any weight forward of the CG. Unless you calculate exactly where you think you can put this radio, you're delusional!

 

[DerAdlerIstGelandet]

BOOOOOOOO!!!

View attachment 599417

BOOOOO I SAYS!!!

 

[glennasher]

Am I reading that chart right? Almost 10% of the total P-39 production was lost in accidents? That percentage says quite a bit, right there...........

Hello PAT303,

You were probably correct, but I try to give folks the benefit of the doubt.
I just don't expect to find religious fanatics when it comes to WW2 aircraft and there is a pretty good chance that is what is happening here.

The discussion wasn't a total waste. Think of all the entertainment we have gotten in the last 15 pages.

- Ivan.

That percentage of "wastage" in training alone should have cancelled the whole program, except maybe in the eyes of those who can't absorb information contrary to their dogmatic beliefs, maybe.

 

[GrauGeist]

From post #541 in this thread:

A quick glance at Joe Baugher's site shows that six P-39s out of the production batch 41-6722/41-7115 (P-39D-BE) crashed due to spin.
There's many more out of the batch that indicate wrecking with no specifics - those could be crossed with the USAAF MACR reports for details.

While I was glancing through that batch of S/Ns looking for spin incidents, I did see a considerable amount of accidents (many fatal) due to training incidents.
And that was just in the 41-6722 through 41-7115 production.

 

[fubar57]

 

[XBe02Drvr]

Is this horse dead yet? Can we avast kicking now?

 

[GregP]

You can't just look at airplane accidents ... I think you have to add in sorties or hours so you can compare apples to apples.

Table 214 lists the accident rates (per hundred thousand flying hours). The highest accident rate was the A-36 at 274, followed by the P-39 at 245. The P-38 was at 139, the P-40 at 188. The P-47 was at 127 and the P-51 was at 105.

So, aside from the A-36, the P-39 had the highest accident rate. We can excuse the A-36 because it was a light bomber and dive bombing is inherently more dangerous than not dive bombing, especially in training. But the P-39 was THE most dangerous fighter (in U.S. service anyway) that was not a dive bomber, too, to fly.

 

[GrauGeist]

Is this horse dead yet? Can we avast kicking now?

Like this, perhaps?

(image source: Fubar57's gallery of nessecary and practical illustrations)

 

[GregP]

So, where exactly is Fubar 57's gallery? Looks like a great source!

 

[jmcalli2]

The Airacuda wasn't an attack aircraft it was supposed to be a bomber destroyer, comparisons to the A-18 are moot.

Did the XP-77 actually achieve 330 mph? The testing program was very short lived. One look at the The XP-77 with the pilot sitting so far aft makes you wonder how effective it could have been. Deflection shooting would be out of the question

The P-59A was not designed as a trainer. It was supposed to be a fighter. Due to it poor performance orders were cut back and it was relegated to the training role.
The J-31 you disparage is basically the Welland used in the Meteor MkI (Both based on the Whittle WB.2/23) which despite being heavier than the P-39A was much faster. As to the Me 262 there is no comparison.
From ch11-2
Although having about the same total thrust as the Me 262, along with a thrust-to-weight ratio over 30 percent greater than that of the German aircraft, the P-59A was slower by about 130 miles per hour. Analysis shows that the 65-percent-greater wing area and consequent greater drag area of the P-59A was responsible for much but not all of the difference in performance of the two aircraft. Perhaps the thick airfoil sections of the P-59A or some other sources of added drag contributed to its poor performance, or perhaps the engines did not perform as anticipated. An obvious question concerns the choice of so large a wing area for the aircraft. In comparison with the 60-poundper-square-foot wing loading of the Me 262, the corresponding value for the Airacomet was 28 pounds per square foot. The use of sophisticated leading-edge and trailing-edge high-lift devices on the Me 262 gave acceptable takeoff, landing, and maneuver characteristics with a small wing area and high wing loading on this aircraft. Only small, simple, inboard trailing-edge flaps were used on the P-59A, and the resultant low maximum lift coefficient no doubt played a large part in dictating the choice of a low wing loading and associated large wing area.
In any event, the poor performance of the P-59A precluded its adoption as a production fighter for the U.S. Armed Forces. The P-59 is included here only because of its historic interest as the first jet aircraft developed in the United States.

As I stated in another post Curtiss, in my opinion, was a basket case long before the end of WWII. Saying Bell was better than Curtiss is, as my uncle used to say, like beating a one legged man in an ass kicking contest. I believe he meant donkeys.

Just a thought on the P-59A; could the huge wing be a 'safety' feature, anticipating engine failures, designed to allow the plane to glide back to base?
P-39 wing loading was much higher than 28 lbs/sqft.

 

[GregP]

At 11,040 lbs, the P-51B's wing loading ws 28.6 lbs.sq in. and 11,040 was takeoff weight for the aircraft. Oh, and they did a lot of gliding because they ran out of fuel semi-often, according to the pilots who flew them. At the Planes of Fame, we've had 3 or 4 guys who flew OUR tail number come and give a talk. Many P-59 pilots ran out of fuel and glided to the nearest airport and called for jet fuel from the nearest bar, which usually had a telephone. Jet fuel wasn't very widely available , even in 1949.

According to the book "Flame Powered" as well as former Bell employees, the huge wings were because they didn't give Larry Bell much information except a big block of wood and told him the engines would not be any bigger than the block of wood. So, Bell designed an engine bay around it, and even had to add engine mounts later when the exact location of them was passed along. They put the big wing on because they didn't have any information and erred on the "more area" side.

Also, they didn't tell Bell how much air the engines used, so the intakes are WAY oversize, and create a lot of drag when air goes in, circulates around in the intake, and leaks back out the front because there isn't enough air used to take it all. I can tell you from personal experience that the build quality is pretty good. But, Bell Aircraft simply didn't have much information about the engines and built what is basically a test bed for the engines.

The follow-on Bell XP-83 flew in Feb 1945 and did 522 mph (840 km/h) at 15,660 ft (4,773 m).

The top speed of the Me 262 A-1 was 560 mph, so the XP83 wasn't far off when Bell had more information. The Me 262 had a service ceiling of 37,000 feet and XP-83's service ceiling was 45,000 feet. The XP-83's rate of climb was 5,650 fpm versus 3,900 fpm for the Me 262. The XP-83's range was 1,730 miles versus 650 miles for the Me 262.

So, again, when Bell had more information, they didn't exactly do badly. The XP-83 beat the Me 262 in all specs except top speed, and the top speeds were very close.