Lightening the P-40

[Clay_Allison]

"I'm obsessed with the concept that the US should have had a true contemporary to the Bf 109 and the Spitfire and I wonder ...."

Clay - stop being obsessed. The USA in the '30's and pre-war '40's was NOT England or Germany. For starters - only in the US did you have such an open disagreement between the USAAF and USN over aircraft engines - radial vs inline. The RN used navalized Spits and Hurricanes with inlines - would the USN have done the same? Never Same with the Germans .. if they had ever got an aircraft carrier in operation - it would have carried Stukas and Me-109's.

If the USN and USAAF had set the same general requirements for fighter aircraft - perhaps you would have had a slightly different outcome. Personally - both the P-40 and P-39 were solid performers that had serious shortcomings. Same with the Wildcat. The only fighter in service on December 7-41 was the P-38 - and it had the hot fighter performance you're seeking but that came with limitations of other sorts.

It is a testament to the wealth of the US - even in the late Depression - that the military had as many options to produce competitive designs. Look at the Seversky Lancer for example - and what it evolved into, the Jug.

Personally Clay, I think most problems with the P-40 rest with the manufacturer - Curtiss Aircraft. They never got it together in wartime the way Bell, Douglas, North American, Grumman, Republic and Boeing did - the Directors were more influenced by short-term profit and loss figures. Consider the planes they built besides the P-40. The Helldiver was seriously flawed as was the C-46 Commando. Plus a few twin-engine trainers and catapult-launched naval observation aircraft.

Curtiss was complacent - not hungry - and the P-40 shows it.

My opinion

MM

You have a really good point with Curtiss. I think the only thing that might have put us on a legitimate even footing with Germany and England in fighters is if North American's P-51 design had been submitted to the U.S. Army instead of the British and made a high priority.

 

[Shortround6]

To get a true contemporary to the Bf 109 and the Spitfire you would have had to give up range.

Many accounts only speak of the top performance numbers in a requirement. Top speed, altitude and climb performance. Hidden in many requirements was also a minimum speed of sorts. Landing speed or landing distance. Carrier aircraft would have take off distances with a certain head wind (no catapults). Add in a minimum range or endurance requirement and you get rather different aircraft.

Carrying an extra 300-400lbs of fuel and tank while keeping the same take off or landing performance means a bigger wing. Bigger wing means more weight which means more fuel to get the minimum range which means.....

Bf 109 started with 2 rifle caliber MGs. Even the E-model was only carrying 2 x 12.6kg (MG 17s) + 2 x 28kg (MG-FF)= 81kg worth of guns. with about 60kg worth of 7.9 ammo and 44 kg worth of 20mm ammo and drums gives a weapon load of 185 kg not including mounts, ammo bins and chutes etc.

Spitfire carried about 80kg of guns and 84kg of ammo (350rpg) for 164 without Mounts, etc.

The US was blessed with, or cursed with, the .50 cal Browning. Two weigh 58kg (29kg each, more than the German MG-FF) and ammo weighs 11.36 kg per hundred so 200RPG gets you 45.46kg for a total of 111.56kg of guns and ammo but no mounts,etc.

Sounds good until you realize that two synchronized .50 Brownings are not exactly world class armament. The synchronization gear drops the rate of fire to about 450rpm per gun or 15 rounds per second for both guns. So you need to add guns (weight) to get in the same league as the British-Germans.

As for:
"..the only thing that might have put us on a legitimate even footing with Germany and England in fighters is if North American's P-51 design had been submitted to the U.S. Army instead of the British and made a high priority."


You do know that the the first British squadron didn't recieve Mustangs until Feb of 1942 and didn't undertake an operational sortie until May 5th 1942? only 17 1/2 months after the prototype first flew. Even if you knock 25% off of that time (4 1/2 months) that leaves you with NO P-51s for Hawaii, the Philippines or other theaters in the first month or two of the war. What the "high priority" does to other production programs might be a negative impact. You still have the engine problem. Poor performance over 15,000ft.

Parts of what hurt American aircraft performance in the 1941-42 period was a refusal of the Authorities to sanction war emergency ratings for the engines that were available (although many units did it on their own). Development of the engines was held back in the 1938-1940 period becasuse the American 100 octane fuel had NO rich mixture rating. It was different gasoline than the British 100 octane and would not allow the rich mixture overboost the British used. The Authorites refusal to use War emegency ratings was in part a legacy of the 1937- 1940 research with American fuel.

Too many things have to change for the Americans to have come up with the fighter you seem to want. And the Americans were trying, it's just that some of the attempts didn't pan out. See P-43 for early turbo-charged fighter. See the original XP-47 with Allison engine.
America wold have had to switch to high aromatic gasoline much earlier than it did to get the rich mixture benifit. Of course the high aromatic gasolines tended to eat some gaskets, hoses and self sealing fuel tank liners on American planes.
Why did Rolls- Royce go for the mechanical two stage supercharger? because they thought they couldn't get a turbo to work in time to make the war. Note also that no other British manufacturer even made a production 2 stage supercharger of any kind during the war.

 

[Clay_Allison]

It is bizarre that America came up with at least 5 planes that were good enough to win the war if any two (or one in some cases) had been the total focus of the Army and Navy's fighter development from the beginning through the end.

The good news about that is they were all good enough by the end that they were all highly effective from mid-44 on.

The Lightning, Thunderbolt, Hellcat, Mustang, and Corsair were good enough to be the only army fighter if we had focused all of our attention on it though the first two could never have been a carrier fighter IMO.

I just wish we hadn't wasted so much time being behind the curve and blissfully ignorant of it during the 1930s.

 

[Shortround6]

It is not so bizarre. America had by far the largest industrial base. I am not saying the American designers were smarter but we had more engineers, more draftsmen, more tool makers (both men and companies) so that we could explore more than one option at a time. It was a time of rapid progess. Aircraft and aircraft engines in the thiries were advancing almost as fast as computers were in the last 10 years.

From the late 20s until the start of the war in 1939 the American CAA issued just over 700 type cetificates for civil aircraft. Granted some of them were for alternate engine installations and some were for "fliver" aircraft but no other nation came close to that number of designs. Engine power pratically tripled (production engines, not race)

And it was done in what would now be considered a scientific vacumm. There were only 12 large (over 5ft) wind tunnels in operation in the US before WW II and only 2 of them were over 20 ft. One was described as a high speed tunnel and it wa 8 ft across and didn't start operating until 1936. By the end of WW II the US had over 40 wind tunnels in operation. In the mid-late 1930s the ONLY way to GUARANTEE success was to pursue several options at the same time.

I am not so sure we were all that far behind the curve. If the P-36 (or it's export variants) weren't quite up to the 109's standard they were at least as good as anything else the French had in numbers. Probably as good as anything the Italians had at the time. And a 4 gun or 6 gun P-36 vrs an early Oscar would be an interesting match-up given equel pilots. The P-36 was only about a year newer than the KI-27 Nate. The Russian I-16 was a bit older.
The US was the only contry to pursue turbo-charging with any success. While it wasn't quite ready for 1941-42 it wasn't because the Army was "blissfully ignorant of it during the 1930s." about 100 turbo equiped aircraft were purchased by the Army in the years before 1939 and before the P-43 in an effort to get ahead of the curve.

 

[Clay_Allison]

While it wasn't quite ready for 1941-42 it wasn't because the Army was "blissfully ignorant of it during the 1930s." about 100 turbo equiped aircraft were purchased by the Army in the years before 1939 and before the P-43 in an effort to get ahead of the curve.

Their sheer ignorance in the matter of refusing to encourage two-stage supercharger development made US fighters suck at high altitude until 1944. It's all well and good to explore multiple options, why didn't we explore multiple options for engine aspiration. It's hard to argue that the army wasn't pretty stupid about the air corps. Self defending bombers and only low altitude fighters ( except the P-38 ) was pretty oblivious to reality.

It says a lot that they progressed from running Billy Mitchell out of the Military for thinking that air power was important to naming a plane after him later.

 

[Shortround6]

Uh, Turbo- superchargers, at least as used by the US from the late thirties on were used in a two-stage supercharger system.

The P-47 "sucked" at at high altitude until 1944

Army orders 13 YP-43s with Turbos at the same time they order the first production P-40s. Goes on to order another 259 P-43s . Granted it is to finance the expansion of the Republic plant for upcoming P-47 production as much as anthing eles but it does provide experience for mechanics and pilots with turboed aircraft. A lot of the experience is bad.

"It's hard to argue that the army wasn't pretty stupid about the air corps. Self defending bombers and only low altitude fighters ( except the P-38 ) was pretty oblivious to reality. "

It is actually pretty easy to argue the army wasn't stupid. Lacking in crystal balls to see the future maybe but not stupid.

Self defending bombers;

Certainly not the only country to think that. Germans after combat experience in Spain and Poland thought only three 7.9mm mg were needed to defend a bomber
British put power turrrets on bombers for daylight operations. Only switched to night bombing when they found that multipule turrets with multipule guns per turret didn't provide enough defense.
Even using "experience" from the Spainish civil war one could argue that the self defending bomber was possiable. Many fighters in the Spanish civil war were armed with only two rifle caliber machine guns. having a bomber with a power turret with even two RCMGs should make things fairly even.
French put 20mm guns on a power mounting in some bombers.
Americans experimented with a 37mm in a power turret in the B-19. Please see B-19 for an idea of how long things could take when trying to stretch the technology of the time or how far into the future planners were trying to see.

Then there is the range problem. In the mid 1930s (or 40s or 50s) you could build a bomber that had much longer range than a fighter. you then had several choices;
1. Limit the range of your bombers to the range of your fighters. Great for bomb load, not so hot if you are the United States and all your potential enemies are thousands of miles away.
2. Build special "escort" fighters like the Bell Airacuda, the Bf 110 and a varity of Fench aircraft. We all know how that option turned out.
3. carry fighters with you under the bombers, tried by the Russians and again by the US using jets in the 50s.
3. Equip your bombers with enough guns to defend themselves.
4. Develop more powerful engines so your fighters can carry both enough guns to be effective and enough gas to accompany the bombers.

3 and 4 kind of go together but in opposite ways. as more powerful engines are developed the interceptors armament increases to a point were no bomber can carry enough guns pointing in any one direction to equal what the fighter can carry. Of course with more powerful engines you can design an even longer ranged bomber.

By the way the Navy used nothing but mechanical drive 2 stage superchargers in their first line fighters.

With rather limited funds for most of the 1930s were should the Army have put it's money?

Remember that in some years more money for airplanes might have ment less money for tanks.

 

[michaelmaltby]

Clay this thread has turned into a discussion about why the US didn't have the "right" planes in 1940-41.

I put it to you that there is nothing unique about this - the US quickly changed it's strategies once it discovered the realities of jet-to-jet conflict in Korea - with the evolution of jets like the Panther, Sabre and Thunderjet. At the outset of VietNam the focus of most top line US aircraft was nuclear - bomb tossing but again, tactics and aircraft evolved very quickly with the Republic Thunderchiefs quickly becoming the conventional tactical bombers with payloads far in excess of WW2 standards.

Mid-air refueling is probably one of the great game changers in the evolution of airwar.

So I return to a point made earlier in this thread - the US military was fortunate to have the luxury of developing/funding parallel projects. Every country did/does that to a greater or lesser degree - and politics play a big part in who wins, not just the best design (Brewster, Seversky, both not too popular with the establishment - likewise there are examples in Germany and the UK).

You - who from time to time pine for a cheap, non-strategic materials fighter for the Australians, India, etc. - should appreciate the ironic difference in unit costs between P-39, P-40 Lend Lease fighters supplied to the Soviets compared to the costs of P-47's and P-38's supplied to US forces --- and I'm not saying the Lend Lease planes were cheap or inferior in quality. Unit costs for cutting edge P-51 and Hellcats were consistently driven down as the engineers got to work on them. [Same for B-25's and A-20 Havocs (Bostons) vs B-26 Marauders.]

So - with regards to aircraft production, productivity and competing designs, it helped that America (and Canadian) factories weren't being bombed - don't you think?

MM

 

[Clay_Allison]

With rather limited funds for most of the 1930s were should the Army have put it's money?

In retrospect? Development of a two-stage centrifugal supercharger for the Allison V-1710. If we had gotten that we'd have had:

The P-40 with good performance up to 25k.
The P-39 as an adequate all-around plane.
Reliable P-38s in the ETO.
The Mustang A without the need for conversion to the Merlin.

 

[Shortround6]

In retrospect? Development of a two-stage centrifugal supercharger for the Allison V-1710. If we had gotten that we'd have had:

The P-40 with good performance up to 25k.
The P-39 as an adequate all-around plane.
Reliable P-38s in the ETO.
The Mustang A without the need for conversion to the Merlin.

We also might NOT have had B-17s and B-24s with turbochargers.
P-40Q which demonstrated 422mph with the 2 stage superhcarger only carried four .50cal MGs. while six guns or four 20mm cannon were talked about for armament the "Q" already weighed over 300lbs more than a six gun "E" did empty and grossed 9000lbs. Adding the heavier armament would have ment a loss of performance. Clipping a foot from each wingtip might have helped speed a wee bit but probably didn't do much for landing speeds or turn rate. The "Q" was strechd to feet to fit the Allison 2 stage supercharger and still no intercooler.
The P-39 is questionable. you need an intercooler to make the the 2 stage supercharger work (or a lot of ADI) which is what caused a lot of trouble with the P-39 in the first place. While the P-63 did have room for the bigger supercharger (it was 2 feet longer than the P-39) it still didn't have room for an intercooler and made do with water injection.
P-38 performace might have suffered at altitudes over 25,000ft.
Might not have had the P-47 or if we did a rather different one.

The two stage mechanical supercharger does extend the operational abilities of aircraft to a considerable extent. It does not extend them to the extent a turbocharger does. The American Turbocharger installations were designed to allow sea level power (take-off) to 27,000ft. later models coud carry sea level power to 30,000ft or a bit above. Now this does not include the jet thrust from the exhaust but that is of the most help at full speed.

As an example the Merlin engine in a P51D Mustang was rated at WER of 1695 at 10,300ft. That is in low gear. It is rated at 1390hp at 24,000ft WER in high gear.
The Turbo-supercharged Allison in the P-38J had a WER of 1600hp at 26,500ft.
Maximum continous power was 1150hp at 17,000ft and 980hp at 29,000ft for the Merlin and 1150hp at 32,000ft for the Allison.

Going back to jet thrust. The jet thrust is the product of the mass of the exhaust gases times their exit velocity from the exhaust stacks. the nozzle size has to be set up for one set of operating conditions so a less than full throttle setting might give slightly lower velocity. Less than full throttle will definatly give less mass. Using the P-38 engine because that it what I have numbers for even though it didn't use jet exhaust. at WER of 1600hp it burned 180gallons an hour. at Military power of 1425 it burend 167 gal/h but at max continous of 1100-1150 hp it burned 113 gallons an hour and at max cruise of 795hp it burned 63 gal/h. About half the propellor HP but 1/3 the fuel per minute going to jet exhaust.the air mass doesn't fall of that bad because the egine geoes from rich mixture to lean mixture but I think we can see that jet exhaust is of less use in cruise conditions.

The Army wasn't totally ignoring the 2 stage mechanical supercharger. They did order the XP-41, a cleaned up P-35 with basicly the same engine as the Wildcat, 2 speed, stage R-1830 and there was a P-36 airframe floating around with the same engine but that may not have been Army funded.

Now if you had funded both supercharger types what do you suggest the Army give up.
The M-1 rifle?
Delay tank development so the Sherman shows up later?
hold off on 105 howitzer production?

To get a little more serious give up on the hyper engine program a lot earlier?

 

[Clay_Allison]

We also might NOT have had B-17s and B-24s with turbochargers.

There is no reason for Allison's concentration on Superchargers to affect P&W's work on turbochargers. Pratt and Whitney managed to develop both superchargers and turbochargers that worked perfectly with the R-2800.

If the Army had not actively discouraged development of the two-stage superchargers, Allison could have done the same. It's a shame that the V-1710 didn't have any Navy customers since Navy engines had superchargers developed for them. As much as you claim we gave ourselves options, the Army put all of its eggs in one basket, the P-38.

In any case, the Lancaster somehow flew without Turbochargers, it managed to make due with Supercharged Merlins unless I am mistaken.

The M-1 rifle?

What did that cost us? John C. Garand's Salary and the very simple tooling setup to create a rifle with 6 moving parts? Be sane.

To get a little more serious give up on the hyper engine program a lot earlier?

Hell yes. That thing never produced anything. Neither did the Ranger V-770. There were tons of pretty crazy projects floating around that apparently got Military money.

I'd also be willing to scrap the P-39 as being a weird design only a Russian could love. Bell could build Mustangs under license as soon as the P-51A was available. The Russians didn't like our P-40s quite as well, but they could probably get used to it. They liked it better than the Hurricane anyway.

 

[Shortround6]

There is no reason for Allison's concentration on Superchargers to affect P&W's work on turbochargers. Pratt and Whitney managed to develop both superchargers and turbochargers that worked perfectly with the R-2800 .

Uh, P&W didn't develop any turbochargers. they adopted General Electric turbochargers. in fact the Wright engines on the B-17 used the same basic model (in some cases the exact model) of turbosupercharger that the P-W engines on the B-24 used. Same basic model used on the P-38. and in dual installations on bothe the B-29 and B-32 with Wright engines.

If the Army had not actively discouraged development of the two-stage superchargers, Allison could have done the same. It's a shame that the V-1710 didn't have any Navy customers since Navy engines had superchargers developed for them. As much as you claim we gave ourselves options, the Army put all of its eggs in one basket, the P-38.

Got any evidence the Army " actively discouraged development of the two-stage superchargers"?

Allison designed their engine on purpose to be a basic building block engine. Different gear cases (including the P-39 extension shaft) and turbo and non-turbo engines could all e built on the same production line and in fact at times one version could be turned into another in the field with suitable spare parts. even teh Doubel Allison, the V 3220 used standard Allison blocks.

As far as the army putting all it's eggs in basket goes, just how far behind the P-38 was the P-47?

In any case, the Lancaster somehow flew without Turbochargers, it managed to make due with Supercharged Merlins unless I am mistaken.

Yes it did. it just didn't fly the same mission profiles did it? a little somthing like the service ceailing being something on the order of 23,500ft?

What did that cost us? John C. Garand's Salary and the very simple tooling setup to create a rifle with 6 moving parts? Be sane .

want to tell us what the 6 moving parts are?
and you have to pay for the rifles to be produced.

Hell yes. That thing never produced anything. Neither did the Ranger V-770. There were tons of pretty crazy projects floating around that apparently got Military money.

Uh, just what military money funded the Ranger V-770? Fairchild had been working on that thing since the early thirties as a commercial engine.

Bell could build Mustangs under license as soon as the P-51A was available.

Not without building P-39s first. Bell had built exactly 13 airplanes not counting P-39s by the time the Mustang first flew. Bell had contracts for almost 1000 P-39s of vairous types by the Mustang's first flight and it was these contracts that allowed for plant expansion and the number of workers needed for mass production.

But in your world all contracts can be canceled and production shifted (and new jigs and fixtures all built) to a new type of aircraft in just a couple of weeks, right?

Contracts can be cancelled but it only makes sense to do so when you can cancel the long lead time supplies and parts in an orderly fashion so as to use up a fair amount of the premade parts. Other wise you hae a buch of partialy completed aircraft and awhole lot of very expensive scrap.

 

[Clay_Allison]

Uh, P&W didn't develop any turbochargers. they adopted General Electric turbochargers. in fact the Wright engines on the B-17 used the same basic model (in some cases the exact model) of turbosupercharger that the P-W engines on the B-24 used. Same basic model used on the P-38. and in dual installations on bothe the B-29 and B-32 with Wright engines.



Got any evidence the Army " actively discouraged development of the two-stage superchargers"?

Allison designed their engine on purpose to be a basic building block engine. Different gear cases (including the P-39 extension shaft) and turbo and non-turbo engines could all e built on the same production line and in fact at times one version could be turned into another in the field with suitable spare parts. even teh Doubel Allison, the V 3220 used standard Allison blocks.

As far as the army putting all it's eggs in basket goes, just how far behind the P-38 was the P-47?



Yes it did. it just didn't fly the same mission profiles did it? a little somthing like the service ceailing being something on the order of 23,500ft?



want to tell us what the 6 moving parts are?
and you have to pay for the rifles to be produced.




Uh, just what military money funded the Ranger V-770? Fairchild had been working on that thing since the early thirties as a commercial engine.



Not without building P-39s first. Bell had built exactly 13 airplanes not counting P-39s by the time the Mustang first flew. Bell had contracts for almost 1000 P-39s of vairous types by the Mustang's first flight and it was these contracts that allowed for plant expansion and the number of workers needed for mass production.

But in your world all contracts can be canceled and production shifted (and new jigs and fixtures all built) to a new type of aircraft in just a couple of weeks, right?

Contracts can be cancelled but it only makes sense to do so when you can cancel the long lead time supplies and parts in an orderly fashion so as to use up a fair amount of the premade parts. Other wise you hae a buch of partialy completed aircraft and awhole lot of very expensive scrap.

You want desperately to believe that it was utterly IMPOSSIBLE to have a two-stage supercharger for the Allison when P&W had no problem making one for the F4F-3 that was in service by pearl harbor.

I don't see why it would be such a big deal if the army had had the foresight to want it. In your world it would cost so much that there would be no way for us to afford to buy GUNS! You are being silly.

I picked some random things we spent too much money on, the P-75 Eagle is another one that comes to mind. You picked the Hyper-Engine, that was a whole engine and that should be enough money right there. I'm talking about an accessory that was actually developed by another company for another engine in EXACTLY the time frame I'm talking about.

 

[Shortround6]

You want desperately to believe that it was utterly IMPOSSIBLE to have a two-stage supercharger for the Allison when P&W had no problem making one for the F4F-3 that was in service by pearl harbor.

I don't see why it would be such a big deal if the army had had the foresight to want it. In your world it would cost so much that there would be no way for us to afford to buy GUNS! You are being silly.

I picked some random things we spent too much money on, the P-75 Eagle is another one that comes to mind. You picked the Hyper-Engine, that was a whole engine and that should be enough money right there. I'm talking about an accessory that was actually developed by another company for another engine in EXACTLY the time frame I'm talking about.

Actually the the P&W engine did have problems in operation if not in manufacture.
I am also not sure how my attempting to correct your aparent misunderstandings of what engines actually used what parts or superchargers translates into "want desperately to believe that it was utterly IMPOSSIBLE to have a two-stage supercharger for the Allison".

It was possiable, you just have to pay for the weight and bulk and understand the limitations which apperently you don't or you never would have compared the Lancaster to the B-17 the way you did.

For anybody else reading this I am not knocking the Lancaster or claiming that the B-17 was better. Mearly saying that they flew different mission profiles and that the Lancaster could not fly at the altitudes the B-17 did.

As to the guns I am simply pointing out that before the war started the Army had some rather strict budget problems. They got easier as the war got closer and got real easy after the war stared in Europe but development and factory construction take time. Every dollar you spend on one item in 1936-37-38 is a dollar you can't spend on something else. I don't think that is silly. I also don't think it is silly to point out decisions that had to be made at the time using knowledge of the time.
I do think it is silly to call peaple stupid for not making decisions that you would agree with based on knowledge gained after the fact.

It is also silly to keep picking things that had no bearing on the decisions we are talking about.

How does canceling the P-75 , the requirement for which wasn't even issued until Feb of 1942 and a contract not isued until oct of 1942 free up any money for research and development in 1938-39-40?

You still haven't provided any evidence that the army "actively discouraged development of the two-stage superchargers"?

or told us what the six moving parts of an M-1 are.

 

[michaelmaltby]

"'... I'd also be willing to scrap the P-39 as being a weird design only a Russian could love. Bell could build Mustangs under license as soon as the P-51A was available..." and you'd be an idiot

The P-39 was one of the great design/function creations of the entire war. The fact that it 'didn't work out' in a big way for the US (or RAF) in no way detracts from it's effectiveness for the Soviets. 15 minutes behind the front. Heavily armed. Takes punishment well. Crash lands very well. Engine good for 35 combat hours. What's not to like in design-conscious Russia.... [Modernism, they called it]

Aircraft design is pushed by the same rules as evolution. The P-39 was designed around the Olds 37 cannon. All other design considerations were influenced by the decision to mount that gun internally, on the centre line. (maybe not the doors and the tricycle ...)

What was learned deploying the P-39 was just as useful as the P-51 or P-47. Look at the L-39 airframe with/without slats -- it's the most advanced swept wing design the US deigned (1946) until the German "influence" kicked in..with a jet-like airframe.

I know the Mustang is a great performer, Clay - and good value too - but the P-39-P63 evolutionary line was very valuable and set the stage for mid-engine mounted turbo-props [dead end - but needed to be explored], and cannon-centric platforms like the Thunderbolt II.

Diversity, diversity ... if you can afford it - go for it

MM

 

[Clay_Allison]

Let me get back to the important parts and leave your silliness about leaving the soldiers without rifles alone. (Yes, that was very silly.) If you actually want to know what the moving parts are, there's a disassembly video on Youtube. I may have even miscounted in my head, my point wass that it was a simple rifle suited to mass production, thanks to a very slick design by Mr Garand.

I don't know exactly how many 1936 dollars it would take to get some research guys from Allison playing with superchargers and trying to get two stages together with an inter-cooler between them. I do know it's not enough money to deprive the army of guns and tanks for the love of all gods.

As to actively discouraging it, I read an article that stated that the Army refused a proposal to make a two-stage supercharged Allison at about the time it became clear that the Turbo would not be able to be included on the P-39 P-40. I didn't save that but I have this:

The production Allison turned out to be the sturdy and reliable powerplant that its designers had striven for. The only thing that stood between the Allison and real greatness was its inability to deliver its power at sufficiently high altitudes. This was not the fault of its builders. It resulted from an early Army decision to rely on turbo-supercharging to obtain adequate power at combat heights.

You came up with a great idea in strangling the hyper-engine in its grave. That thing underwent any number of changes without a single reliable power plant being delivered to my knowledge in a useful time frame. All it ever spawned were failed one-off aircraft designs, again, so far as I know.

I don't see that development being very hard considering:

The engine design benefited from the General Motors philosophy to build-in production and installation versatility. The engine was constructed around a basic power section from which different installation requirements could be met by fitting the appropriate Accessories Section at the rear and a tailored reduction gear for power output at the front. This approach allowed easy changes of the supercharger(s) and supercharger drive-gear ratio. That gave different critical altitude ratings ranging from 8,000 to 26,000 feet (2,400 to 7,900 m). It allowed a variety of propeller drives and also remote placement of the reduction gear.

I've introduced like 17 different ideas solely for the purpose of how the US could have had high altitude fighter capability from January 1942 until the P-47 became truly available in quantity, putting that problem to rest. Lightening the load, superchargers, differentiated fighters (P-39 as the high altitude interceptor, P-40 as the Fighter-Bomber).

All I get are near hysterical responses like "If the Army paid Allison to work on designing an engine part that already existed, the Army wouldn't have guns!!!!1!1!"

Can you imagine that this might be frustrating? Does everyone just believe that just because something didn't happen then it couldn't have possibly been done any differently? Do we live in the best of all possible worlds?

I've spent entire days at work thinking about this, and I'm not married to any particular idea. I just think that problems exist to be solved and I like to work on them until I have an agreeable solution, even to problems that once existed but no longer do.

Either tell me that it was against some magical law of nature for the US to be able to operate competitively at 25000 feet, or tell me there would be a better way to do it.

 

[Shortround6]

I would suggest that you read some books on engines and quit relying on Wikipedia.

AS to the M-1 rifle yes it was a slick design and it aslo happened that Mr. Garand was not only a great gun designer but a great production engineer and designed new tools, jigs and fixtures to make the M-1.

I also own one.

1. Allison had a development staff of 25 engineers at the time they were working on the Airacuda.
2. Continental had gotten 1/2 million from the army from start of the hyper program and the army insisted on several very questionable design features.
3. the army and navy had given Allsion about 1 million dollars and General Motors had sunk 900,000 dollar into the project.
4. the army had been insisting on fuel injection until about 1936 when Allison told them they simply could not do it. they didn't have the resources to develop the fuel injection and develop the engine at the same time.
5. Up until 1940 Alison had made 67 V-1710 engines and 48 of them were in 1939. This was not a large company even if it did have GM behind it.
6. For most of the 1930s General Electric had supplied ALL US aircraft engine makers with the superchargers used on thier engines. If not the actual superchargers then they supplied the designs. It was only in the late thirties that manufacturers became dis-satisfied with the performance of the GE mechanical superchargers and began designing their own. This means that there is a distinct lack of supercharger design experience in the US. This may be not be a bad thing considering #7
7. One of Stanley Hookers claims to fame is that he realized very shortly after to going to work for R-R that a number of the formulas tha peaple were using to design superchargers had errors in them. So if your bright young guys at P-W or Allison were using these text book formulas they were going to get pretty much the same poor results that everybody else was getting.
8. About 70% of all wildcats produced DID NOT use a 2 stage supercharger and this was after it had already been used on the first 30%. Both air cooled radials of almost identical size and running at the same rpm. This should have been the easiest conversion ever yet it was not done. why?

Nice quote on the Allison. but what you don't seem to grasp was that this design set-up ment that the second stage would have to be spaced out from the engine and add more length than the the Merlin set up. Not impossiable to fit in, just more difficult like a minor 1-2 foot extension of the fueslage.

Many of your "17 Ideas" would have been rejected by the peaple in charge at the time. In fact they were rejected by the peaple in charge at the time.
1.Take out armour to lighten the load.
They just got done putting the armour in. They Knew exactly how much performance the armour cost them because they had (at least in the P-40) examples with and without armour. British and Amrerican authorities considered planes without armour, bullet proof wind screens and self sealing tanks as trainers. It seems like your idea is that if we lighten the plane enough we we will get better perfomance and the better performacne will save pilots lives. Didn't the Japanese try that? and we know how that worked out.
2. P-39 as high altitude interceptor. Fine idea except it just wouldn't work. P-39 as built with turbo failed miserably to get near it's predicted performance. Plane just did not have enough internal volume to fit an adequate intercooler. No intercooler= no high altitude performance. There are photos of two later atempts to fit mock up intercoolers to P-39s. One really ugly "saddle" unit behind the cockpit and an underslung pod that looks like a jet engine booster pod. Both increased drag to such an extent ( cut speed by over 30mph) tha no further atempts were made.
3. Superchargers? it is interesting to note that as far as I can tell 3 companies succeeded in making PRODUCTION mechanical drive (non-turbo) two stage superchargers during the WW II era. Rolls-Royce, Pratt Whitney and Allison. Any others? If it is so simple why didn't other companies do it, especially when they had examples to look at, either from allies, other companies in the same country or captured examples.
There is little detail about the early P&W unit. It is mentioned that it had surging problems at high altitude and it seems that it's second critical altitude was about 19,000ft, which while better than the 12,00-15,000 ft of of the single stage superchargers of the time doesn't seem to offer sparkling performance at 25,000ft.
R-R got very lucky with their two stage unit. 1st they had Hooker who manganged to transform their single stage supercharger (P&W may have been trying to use two early type compressors but I am speculating), 2nd their first test rig used a Vulture supercharger feeding into the Merlin supercharger. By good luck this turned out to be a very close match and only minor modifications were needed to match airflows. This may have saved weeks if not months. Allison got into the game late and didn't get a workable setup until 1943 or so and then was handicapped by installation problems, P-63 inspite of being bigger than P-39 still didn't have room for an intercooler.

"All I get are near hysterical responses like "If the Army paid Allison to work on designing an engine part that already existed, the Army wouldn't have guns!!!!1!1!"

A. This engine part didn't exist as working hardware untill 1938 or so. It made it's first flight feb of 1939.
B. without the US actually being in the war how do you get P&W to turnover their intellectual property (patents and engineering data) to allison. P&W might just be trying to sell 2 stage R-1830s to the Army themselves. Not much luck there. See the XP-41 and no it did not use a turbo charger. For specs of the engine see: http://www.enginehistory.org/ModDesig/I40.tif
and look up R-1830-19
C. Do you have any idea of what army budgets were like in the 30s?
D. you seem to want to have your cake and eat it too. I am trying to point out that in the years leading up to WW II the Army (or navy) was limited as to the number of avenues they could pursue. in the late 30s things got a lot easier but it was only in the 1939-1940 that money really started flowing and in fact a lot of plant expansion and plant construction was actually financed by the British and French. Of the 1155 engines delivered in 1940, 705 of them were for foreign orders and of the 6437 engines delivered in 1941, 3645 were for foregn orders. Most of this was before lend lease and were cash sales.
E. during the 1930s the Army only paid for engines or developments that passed acceptence tests or requirements. NO money was paid out before hand and if an engine broke or needed modification to pass the test it was at the manufacturers expense.
F. I cerrtainly don't think my asking you to chose between the M-1 and your supercharger is anymore "hysterical" than your attemt to claim you could come up with R&D funds in 1938-1941 by canceling a proect that doesn't even start until late 1942. By the way, the army would have had guns, just that they would have been bolt action Springfields and Enfields.

"Either tell me that it was against some magical law of nature for the US to be able to operate competitively at 25000 feet, or tell me there would be a better way to do it. "

No magic law. Just bad timing on the part of the US or wrong intial requirements. Larger fuel capacities of US planes ment larger aircraft for same power. The American .50 while a good gun was not the most weight efficient. US planes may have been bult to a slightly higher strength requirement than the British meaning a heavier structure. put them all together and the American planes were heavier for their HP than the English and German planes. No magic bullet to sove problem as each change brings it own problems.
The Bf 109 also used less boost to make it's rated power so an early type supercharger could actually maintain the needed boost a little higher than a British or American engine. If the DB engine was rated at 1.3 atmosphers it was running about 39-40in of pressure. If its super charger could only give a pressure ratio of 2.8 it could mantain the 39-40 in of pressure to a greater hight than an engine that needed 42-45 in of pressure to make rated power.
Please note that this may not have been a concious choice of the engine designer. It just may have worked out that way, larger, slower revving engine needed less boost to make it's power but if built to the same weight as the smaller engine it might not be strong enough to take a lot more boost later on.

 

[michaelmaltby]

Great post, Shortround6, very informative.

MM

 

[michaelmaltby]

"... Donaldson R. Berlin, the P-40's designer, has said that P-40s experimentally equipped with turbo-superchargers outperformed Spitfires and Messerschmitts and that if it had been given the engine it was designed for, the P-40 would have been the greatest fighter of its era. This may be to some extent the bias of a proud parent, but there is no doubt that the deletion of the turbo-supercharger ruined the P-39..."

You'd have liked Donaldson R. Berlin, Clay

MM

 

[Marshall_Stack]

It's a shame that the V-1710 didn't have any Navy customers since Navy engines had superchargers developed for them.

The V-1710 was developed by the Navy for its airships, so it was a customer, just not for its fighters.


Great discussion everybody!

 

[Colin1]

You'd have liked Donaldson R. Berlin, Clay

You'd have liked Donovan Berlin even more