A what if about the P-51...

[FLYBOYJ]

Now Mr. Allison may have a different idea of a light fighter than I do but the Bell XP-77 was a first class turkey.

Was it? Only 2 were built and one crashed and the concept for a light weight fighter to be built from non strategic materials simply vanished as the war went on. Additionally during its development, the Army and Navy (yes they were interested in the aircraft as well) changed specifications which had the aircraft over weight and behind schedule. Although some say its performance was disappointing, to get 330 mph out of a 550 hp engine is nothing to scoff at.

Had the need been there and more time been available for development and the design specs not changed, the P-77 had some potential. It would not have been a major impact fighter like the P-51 or P-47, but it could have served well if time and money became a factor. Additionally the tricycle landing gear would have been a plus for green pilots.

 

[Clay_Allison]

Light weight fighters were losers.

The idea is atractive on the surface and has been pursued by a number of nations and/or companies but the only times it has been successful is when a breakthrough in engine technology has allowed the "light weight fighter" to use an engine with a much higher power to weight ratio than the conventional "heavy fighter".

If you are using planes of the same technolagy level, say piston engine planes of 1940 then the light fighter has several strikes against it.
1. the higher power engines ussually had better power to weight ratios than medium powered engines, they also had better power to frontal area ratios.
2. the was a certain amount of 'fixed' weight in a fighter. pilots couldn't be scaled down by much, instraments, radios, oxogen equipment etc. this weight is a smaller fraction of the larger fighters weight which means that on a percentage basis it should be able to carry more armament, or more fuel than the light fighter.
3. light fighters have limited growth potential. They are less adaptable to other roles.

Now Mr. Allison may have a different idea of a light fighter than I do but the Bell XP-77 was a first class turkey. The French Caudron series seem to be total failures as combat planes. Lots was promised but little delivered. The Italian Ambrosini series may have had serious issues also.

I don't like the XP-77, XP-57 or any other plan that uses a second rate engine. On the other hand, the Miles M.20 was a fantastic plane that tested very well. the British just didn't need it because they already had a non-strategic-materials fighter (the Hurricane). The VG-33 was another good example that I think was a very good plane. The MB2 looks awful but might have been good with a decent power plant as it tested well. The Finns made a prototype wooden copy of the Bf-109 toward the end of the war.

My definition of a light fighter is any fighter that gets the most horsepower per pound that is possible from non-strategic materials and an adequate armament package.

 

[Shortround6]

Was it? Only 2 were built and one crashed and the concept for a light weight fighter to be built from non strategic materials simply vanished as the war went on. Additionally during its development, the Army and Navy (yes they were interested in the aircraft as well) changed specifications which had the aircraft over weight and behind schedule. Although some say its performance was disappointing, to get 330 mph out of a 550 hp engine is nothing to scoff at.

Had the need been there and more time been available for development and the design specs not changed, the P-77 had some potential. It would not have been a major impact fighter like the P-51 or P-47, but it could have served well if time and money became a factor. Additionally the tricycle landing gear would have been a plus for green pilots.

There is some doubt as to weither the XP-77 did manange the 330mph. Or if it did was it carring guns at the time. Major discrepancies in climb performance figures. The two .50 cal mg armament wasn't very impressive for the time it was concieved let alone built (granted it was concieved with a 20mm cannon but think about it). Some sources say initial performance estimates were based on faulty wind tunnel data.
Full scale testing in NACA wind tunnel couldn't cure engine overheating problems.
Bell's other commitments and the reakization that this thing wasn't going to hit perforemance estimates may have also slowed work.

 

[Colin1]

Sorry, should have been more specific. I mean to say that the Mozzie proves that wood can work in combat aircraft. I made the mistake of thinking everyone had heard my "plywood powerhouse" theory. I've said in other threads that the US should have made a light plywood fighter to lend lease to allies who had a hard tome getting planes.

My bad
you were talking about wood, I thought you were talking about engines - a single-engined aircraft based around the success of a twin-engined aircraft?!?!

 

[Shortround6]

I don't like the XP-77, XP-57 or any other plan that uses a second rate engine. On the other hand, the Miles M.20 was a fantastic plane that tested very well. the British just didn't need it because they already had a non-strategic-materials fighter (the Hurricane). The VG-33 was another good example that I think was a very good plane. The MB2 looks awful but might have been good with a decent power plant as it tested well. The Finns made a prototype wooden copy of the Bf-109 toward the end of the war.

My definition of a light fighter is any fighter that gets the most horsepower per pound that is possible from non-strategic materials and an adequate armament package.

I am having a little trouble with your defintion. It is all well and good as you state it but your examples seem a bit fuzzy if "light" has any reference to weight.
Yes, the Miles M.20 was a fantastic airplane, it was also one ton heavier than a MK I Spitfire when loaded. The Martin Baker was only about 250lb lighter than the Spitfire.
The Hurricane wasn't exactly non-strategic-materials fighter. The vast majority of production were fabric covered from the cockpit back but the wings were aluminum covered and the frame work was a mixture of steel and aluminium.
THe VG-33 while using a smaller wing was actually just about the same weight as a Dewoitine D.520.
How much more than the 109 did the Finnish fighter weigh?
Japanese made a wooden prototype of the Ki 84. it gained 600lbs which was If I remember correctly lighter than the all steel version.

tell me you want a non-aluminium or non-strategic-materials fighter. I just get confused when you call it "light"

 

[Colin1]

The Hurricane wasn't exactly non-strategic-materials fighter. The vast majority of production were fabric covered from the cockpit back but the wings were aluminum covered and the frame work was a mixture of steel and aluminium.

I would agree
canvas fuselage skinning and elevators/ailierons weren't so much non-strategic materials as legacy materials, a carry-over from the biplane era; they didn't realise how quickly fabric was going to run out of steam with the sleek, new monoplane fighters.

 

[FLYBOYJ]

There is some doubt as to weither the XP-77 did manange the 330mph. Or if it did was it carring guns at the time. Major discrepancies in climb performance figures. The two .50 cal mg armament wasn't very impressive for the time it was concieved let alone built (granted it was concieved with a 20mm cannon but think about it). Some sources say initial performance estimates were based on faulty wind tunnel data.

And can you name those sources? This is from Baugher. One of my early flight instructors actually worked on the program and he confirmed just about everything said on that site.


View: https://www.youtube.com/watch?v=vsgahU5LUrI

There were many good attributes in this design, time just over took it.

 

[Clay_Allison]

I am having a little trouble with your defintion. It is all well and good as you state it but your examples seem a bit fuzzy if "light" has any reference to weight.
Yes, the Miles M.20 was a fantastic airplane, it was also one ton heavier than a MK I Spitfire when loaded. The Martin Baker was only about 250lb lighter than the Spitfire.
The Hurricane wasn't exactly non-strategic-materials fighter. The vast majority of production were fabric covered from the cockpit back but the wings were aluminum covered and the frame work was a mixture of steel and aluminium.
THe VG-33 while using a smaller wing was actually just about the same weight as a Dewoitine D.520.
How much more than the 109 did the Finnish fighter weigh?
Japanese made a wooden prototype of the Ki 84. it gained 600lbs which was If I remember correctly lighter than the all steel version.

tell me you want a non-aluminium or non-strategic-materials fighter. I just get confused when you call it "light"

I want a non-aluminum fighter of about the same size category as the Spitfire and Bf-109. I was mixing my point somewhat there mentioning other non-strategic-materials designs that weren't necessarily small.

Let me put it in concrete terms: An Allison-powered fighter under 7000 pounds loaded weight with 4x.50 MGs (I'd prefer 2x 20mm cannon but US built cannons didn't work). Basically, the Arsenal VG-31 with an American armament package would be ideal.

 

[Shortround6]

And can you name those sources? This is from Baugher. One of my early flight instructors actually worked on the program and he confirmed just about everything said on that site.

Bell XP-77.

Well. looking at the source you are providing I would point to the 2 climb figures. Intial rate of climb 3600/min and climb to 9,000ft in 3.7 minutes. I would say there is a discepency between those two numbers.

As for the cooling problm try:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890067686_1989067686.pdf

DO I really need sources to say that 2 syncho-ed .50 cal Brownings (rate of fire around 450rpm each) were not an impressive armament in 1941-42?

Now, I am an American and fairly patriotic but thinking that the Americans can build a useable fighter that weighs 2/3rds of what a ME 109 does yet carries a heavier install gun armament (If you include the 20mm) while using an engine a little over 1/3 as powerful takes a lot more hubris than I can muster.

The XP-77 did not have the intended engine installed on the 2 ships built.

Quite true. the engine it was supposed to have seems to be a bit of a mystery. The Planiol supercharger used several axial "stages" before the centrifugal stage and promised higher efficency than a single stage supercharger and perhaps a higher pressure ratio. It was promised to deliver 500hp at 27,000FT.

The engines that were installed however could deliver 520 hp for take off and were rated for 520hp at 12,000ft so low altitude performance should not have suffered. These engines however were only rated at this power level for ONE minute.

As far as Bell purposely slowing down development on this aircraft, more speculation. During WW2 and the same today, defense contractors are penalized for not meeting deadline dates and usually funding is with held. In bells case the government might have allowed the schedule to slip based on needs elsewhere.

From page 25 of "US Army Air Force FIghters part 1" by William Green and Gordon Swanborough.
"Bell's other commitments, however-which included production of the P-39 and the P-63 and ,eventually, the development of the P-59 jet fighter- limited the effort that could be expended on the XP-77, and this, combined with the lack of the supercharged engine, growth in bare weighht of the prototypes, reduced performance estimates, overrunning costs and increased supplies of aluminium led to interest in XP-77 program waning during 1943."

Bell at some point had also subcontracted the construction of the wings and fuselage to the 'Vidal Research Corperation' who apparently sufferd delays in said construction which pushed back the compleationof the protoypes.

There were many good attributes in this design, time just over took it.

There were many "good attributes" promised by this design, time and reality overtook it.

 

[FLYBOYJ]

Well. looking at the source you are providing I would point to the 2 climb figures. Intial rate of climb 3600/min and climb to 9,000ft in 3.7 minutes. I would say there is a discepency between those two numbers.

As for the cooling problm try:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890067686_1989067686.pdf

GREAT INFO - one thing I didn't see in the report was the placement of baffling around the engine and I suspect this was modified at a later date to the last XP-77 that was flown around after the war.

The shape of the cowl is one part of the equasion to rememdy recip cooling problems. The second is the proper placing of baffling around the engine.

DO I really need sources to say that 2 syncho-ed .50 cal Brownings (rate of fire around 450rpm each) were not an impressive armament in 1941-42?

There I agree, but remember - many times the government is the one that dictates armament requirements. The contractor will either follow through or offer more than when the government asked for.

Now, I am an American and fairly patriotic but thinking that the Americans can build a useable fighter that weighs 2/3rds of what a ME 109 does yet carries a heavier install gun armament (If you include the 20mm) while using an engine a little over 1/3 as powerful takes a lot more hubris than I can muster.

Possibly, but again, you're also mentioned with a government specification and contract that will dictate certain criteria, sometimes that criteria dooms a project before it gets off the ground.

Quite true. the engine it was supposed to have seems to be a bit of a mystery. The Planiol supercharger used several axial "stages" before the centrifugal stage and promised higher efficency than a single stage supercharger and perhaps a higher pressure ratio. It was promised to deliver 500hp at 27,000FT.

The engines that were installed however could deliver 520 hp for take off and were rated for 520hp at 12,000ft so low altitude performance should not have suffered. These engines however were only rated at this power level for ONE minute.

Actually that sounds about right for in lines of the period. The V-770 developed max hp at over 3000 RPM - kind of high for an engine of the period. I believe the engine/ propeller combo along with the way the engine was mounted to the airframe might have contributed to this.

From page 25 of "US Army Air Force FIghters part 1" by William Green and Gordon Swanborough.
"Bell's other commitments, however-which included production of the P-39 and the P-63 and ,eventually, the development of the P-59 jet fighter- limited the effort that could be expended on the XP-77, and this, combined with the lack of the supercharged engine, growth in bare weighht of the prototypes, reduced performance estimates, overrunning costs and increased supplies of aluminium led to interest in XP-77 program waning during 1943."

Bell at some point had also subcontracted the construction of the wings and fuselage to the 'Vidal Research Corperation' who apparently sufferd delays in said construction which pushed back the compleationof the protoypes.

Got the same book - even though a portion of the contract was subcontracted out, Bell would have still been responsible to deliver at the agreed date. Only the US government would have let them off the hook without penalty.

There were many "good attributes" promised by this design, time and reality overtook it.

Agree.

There were two other competitors in this light weight fighter competition as well.

Douglas XP-48 - Wikipedia, the free encyclopedia

Tucker XP-57 - Wikipedia, the free encyclopedia

 

[Shortround6]

Going back to the premis of the light fighter (using low powerd engines) the XP-77 helped show that you couldn't really carry an effective armament with competative performance using the low powered engines.

For more information on Ranger engines see:
http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgMakeModel.nsf/0/E0785E0B6C2E5B3E8525670C00530629/$FILE/TC232.pdf

One book does claim that the 330mph was achived using "military" power but I can't seem to find a Military power rating

At least one account says Bell was asking to be let out of the contract. Aircraft manufacurer could also be penalized if aircraft failed to reach promise performance. Bell may have been looking at losing money either way. Just speculating but maybe they figured that if they were going to lose money anyway why throw good money after bad and pay for more engineering time and development costs if they thought the plane would not meet performance gaurantee no matter what they did? With chances of production contract (to cover cost overruns) getting dimmer why not just pull the plug and take their lumps?

 

[FLYBOYJ]

Going back to the premis of the light fighter (using low powerd engines) the XP-77 helped show that you couldn't really carry an effective armament with competative performance using the low powered engines.

In WW2 yes - that changed years later

At least one account says Bell was asking to be let out of the contract. Aircraft manufacurer could also be penalized if aircraft failed to reach promise performance. Bell may have been looking at losing money either way. Just speculating but maybe they figured that if they were going to lose money anyway why throw good money after bad and pay for more engineering time and development costs if they thought the plane would not meet performance gaurantee no matter what they did? With chances of production contract (to cover cost overruns) getting dimmer why not just pull the plug and take their lumps?

Possibly, but defaulting on a contract may effect a company from future bidding.

 

[Shortround6]

In WW2 yes - that changed years later.

Yes it did. the Folland Gnat being a great example but compare the power to weight ratio of the Folland's Orpheus engine to the power to weight ratio of the Engines used in the admittedly older Sabre jet.

Using engines that have a similar power to weight ratio ( or actually slightly worse in the Rangers case) doesn't offer the designer any wiggle room.

Possibly, but defaulting on a contract may effect a company from future bidding.

True but if you can get the Goverment to agree?
And if you are trying to get the goverment to agree and let you out of the contract how many peaple are going to autharize overtime or 3 shift work on what is percieved as a doomed project?

 

[FLYBOYJ]

True but if you can get the Goverment to agree?

Whole different story

And if you are trying to get the goverment to agree and let you out of the contract how many peaple are going to autharize overtime or 3 shift work on what is percieved as a doomed project?

The "shift work" to fulfill a contract is usually left up to the contractor unless the government requires round the clock production. When shift work is planned by the contractor they usually factor in overtime during the bid. Again if you could get the government to let you off the hook, all bets are off.

BTW - you posted the "Type Certificate Data Sheet" for the Ranger.

http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgMakeModel.nsf/0/E0785E0B6C2E5B3E8525670C00530629/$FILE/TC232.pdf

It does not include the -9 engine

 

[DerAdlerIstGelandet]

Now Mr. Allison may have a different idea of a light fighter than I do but the Bell XP-77 was a first class turkey.

Really? Everything I have read on the aircraft states that it was not really good. It had vibration problems because the engine was mounted directly to the airframe without and absorbers or dampening. It was difficult to fly and visibility was not that great.

They did not just terminate the program for nothing, and the fact that the shortage of aluminum never happened was not the only reason.

 

[Clay_Allison]

Really? Everything I have read on the aircraft states that it was not really good. It had vibration problems because the engine was mounted directly to the airframe without and absorbers or dampening. It was difficult to fly and visibility was not that great.

They did not just terminate the program for nothing, and the fact that the shortage of aluminum was not the only reason.

"First Class Turkey" is a negative description..

 

[Shortround6]

Whole different story

BTW - you posted the "Type Certificate Data Sheet" for the Ranger.

http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgMakeModel.nsf/0/E0785E0B6C2E5B3E8525670C00530629/$FILE/TC232.pdf

It does not include the -9 engine

True but then the -9 may never have compleated certification tests , if it was ever submitted for such tests.
Seeing as how it was a military engine it may not have had a civil equivelent.
I have data for several post war Rangers (other D series) as published in several editions of "aircraft engines of the world" by Paul Wilkinson but none of them seem to show up in the online FAA records either.

I just posted the FAA data as the best "official" data I have come across so far.

 

[DerAdlerIstGelandet]

"First Class Turkey" is a negative description..

Oops I missed the Turkey part. I was only seeing the "First Class" part.

 

[FLYBOYJ]

True but then the -9 may never have compleated certification tests , if it was ever submitted for such tests.

True.

Seeing as how it was a military engine it may not have had a civil equivalent.
I have data for several post war Rangers (other D series) as published in several editions of "aircraft engines of the world" by Paul Wilkinson but none of them seem to show up in the online FAA records either.

And many times the TCDS holder may be different from the manufacturer. For example, did you notice at the bottom of the TCDS for the Ranger there was a note that stated that engines produced after 1950 are not eligable for installation on type aircraft (or something to that effect)? Well some one could go in and acquire the TCDS under a different name and get the engine re-certified. This has been done with a number of warbirds and helicopters.

I just posted the FAA data as the best "official" data I have come across so far.

TCDS are usually pretty spot on for information and other data, such as accessories and other engine components.