SHOULD the P39 have been able to handle the Zero? Was it training or performance?

[Elmas]

It is all very well and good to talk about installing two stage superchargers on P-39s. p-40s and early P-51s...........except...........





they don't fit.
...

Amateurs talk strategy, professionals talk logistic.

U.S. Army adage.

So in while in Military Aeronautics amateurs talk speed and climb rate, professionals talk about effectiveness to carry out the mission, safety of the handling by an average Pilot, speed of construction, maintenance and repair…

I bet that there are thousandhs of armchair Pilots that strongly believe that this monstruosity

could have been the best fighter of WWII.

If they only had installed a more powerful engine on it…

 

[pbehn]

Amateurs talk strategy, professionals talk logistic.

U.S. Army adage.

So in while in Military Aeronautics amateurs talk speed and climb rate, professionals talk about effectiveness to carry out the mission, safety of the handling by an average Pilot, speed of construction, maintenance and repair…

I bet that there are thousandhs of armchair Pilots that strongly believe that this monstruosity

View attachment 487050

could have been the best fighter of WWII.

If they only had installed a more powerful engine on it…

Not so fast Elmas I have seen the Mx MCLMXXXIV version in "Star Wars" and it turned out to be a world beater

 

[MIflyer]

"could have been the best fighter of WWII.

If they only had installed a more powerful engine on it…"

Yep. The J-33.

 

[Elmas]

Great post Elmas, but knowledge of washout couldn't just be just held in Germany, the Spitfire flew with it in 1936.

Quite true, for this very reason Mitchell was such a great aircraft designer. Let's think that all these things were more or less "military secrets" and their circulation was not widespread.
And not only for this, as Mitchell was one of the first aircraft designers to fully understand the structural possibilities of D-boxes and stressed skin structures. This allowed him to design a wing with a profile with a thickness at the root that some of his Colleagues were afraid to use even at the wing tip... Spitfire wing was a piece of art, not just a piece of engineering.

 

[pbehn]

Quite true, for this very reason Mitchell was such a great aircraft designer. Let's think that all these things were more or less "military secrets" and their circulation was not widespread.
And not only for this, as Mitchell was one of the first aircraft designers to fully understand the structural possibilities of D-boxes and stressed skin structures. This allowed him to design a wing with a profile with a thickness at the root that some of his Colleagues were afraid to use even at the wing tip... Spitfire wing was a piece of art, not just a piece of engineering.

Was it a case of many competing theories all of which had some merit but the best choice is only known after much time has passed? Car and motorcycle suspension went round and round in circles for decades finishing up with systems first used in the 1930s for some uses.

 

[Shortround6]

I would note that the main difference between a good mechanical two stage system and a good turbocharger tow stage system is that in the turbo system the auxiliary supercharger is driven by an exhaust gas powered turbine and not a driveshaft from the engine.
You still need the auxiliary impeller and casing and you still need the intercooler and ducting (or intercooler radiator).
Anybody who thinks you can have a significantly smaller mechanically driven two stage system is either settling for less performance or fooling themselves.

 

[Shortround6]

I bet that there are thousandhs of armchair Pilots that strongly believe that this monstruosity

View attachment 487050

could have been the best fighter of WWII.

If they only had installed a more powerful engine on it…

Well, it was originally planned for that world beating, super sophisticated, paragone among aircraft engines the Continental IV-1410 and was forced to fly with one of those lousy Allisons

 

[Elmas]

Most probably, things like wash-out were, who knows, discovered by chance: if you make a lot of study someting happens, like Penicillin…

Germans, between the Wars, not being allowed to spend money on a numerous army, spent some money making a lot of research both in aerodynamics and structural engineering, in particular of bending and stretching of thin plates, a theoretical research they started well before WWI.

And Mitchell, as is explained in the biografy written by his Son Gordon, a most interesting read, always kept an eye on what was happening in Germany.

 

[JJWilson]

Still not seeing how the P-39N was in action in the SWPA in 1942. Pacific Wrecks has a list of P-39 losses, the earliest of which seems to be August 1943. While it does not list delivery dates, I find it hard to believe it was in action for 8 - 9 months without a loss.

Also, again, one test of a lightly loaded P-39 does not an operational plane make. You still contend that a fully loaded P-39 can out climb a fully loaded P-38 or P-51? We're talking combat ready, fuel and ammo.

And no, the air war WAS NOT over by March '44.

Hello Peter, I totally agree with your comment on the P-39 and it's climbing ability against two very good climbing aircraft. As for P-39N's being used in the SW Pacific, I also don't recollect hearing about N-Variant P-39's being used there in 42.

 

[Shortround6]

One source says the K and L didn't get to the SWP until 1943 which makes getting the N there in 1942 even more suspect.

 

[MIflyer]

"You still need the auxiliary impeller and casing and you still need the intercooler and ducting (or intercooler radiator)."

Yes, and the odd thing is nobody but Stanley Hooker seems to have thought of the idea of a liquid cooled aftercooler, even after he did it and it was in production.

When you consider that Hooker was a theoretical aerodynamicist and "not much of an engineer" to use his boss's phrase, you can really see how much genius was involved. Hooker had been fine tuning RR supercharger designs by reducing the ram intake losses and air entry angle for the impeller. For him to instead go to a liquid cooled aftercooler that would enable the package to fit under the hood of a Spitfire or Mustang meant he had to step outside his narrow specialty.

 

[Hansie Bloeckmann]

Just my opinion, but what the Allison needed was not a two speed supercharger but a (mechanical, not turbo) two stage supercharger.

We've had the two speed argument here before, and I still maintain that low gear's purpose is just to keep the pilot from overboosting the engine at takeoff and low altitude. The P-39 had plenty of performance at low altitude with their single speed unit regulated by the pilot in early models and the automatic boost control after mid '42. The Allison's single speed was in effect "high" gear, and the need for low gear was eliminated by the autoboost control. The whole two speed vs one speed argument is moot in my opinion.

The two STAGE engine was needed to keep up with the two STAGE Merlin 61 and the two stage R-2800s. The two stage engine provided more power at higher altitudes because the first (or auxiliary stage whether it be mechanical or turbo) stage boosted the thin air at high altitude up to sea level thickness and discharged it into the second (internal) stage which boosted it even further to get those fantastic speeds at high altitude. In effect, the first stage fooled the second stage into thinking it had sea level (high density) air at 25000' boosting power tremendously.

Please remember that the two stage engine was pretty much a British/American product. Americans had turbos and mechanical second stages and the British had only mechanical. The Germans, Japanese and Russians didn't have two stage engines in production planes. They had single stage engines, consequentially their critical altitude was around 18000', whereas two stage engines critical altitude was much higher. The two stage engines came into combat in mid 1942 (Spitfire IX), late 1942 (P-38), mid 1943 (P-47). High speeds for these planes was at 25000'-30000'.

Now there WAS a two stage mechanical Allison, the first production model was the V-1710-93 for the P-63. It featured a separate second stage supercharger driven by a jackshaft from the Allison starter dog that drove through a hydraulic clutch that automatically regulated manifold pressure. The -93 developed 1325HP for takeoff and 1180HP at 21500' with 1825HP war emergency. This pushed the P-63 without wing guns to 422mph at 24000'. They bolted a comparable model onto a P-40 and called it the Q and even that old P-40 went 418mph at 24000' and climbed like a rocket. Only 3 of those Q's were built.

More importantly the -93 was in full production in April 1943 and the P-63 didn't fly until October. Why in the world didn't the Army just put one in the P-39? It fit into the experimental P-39E. The contemporary P-39 model was the P-39N at 7650#. Add the 200# auxiliary stage and balance the weight with a larger 4 blade propeller and you have a real hot rod at 8050#. By July 1943 these P-39s would be coming off the production line and would have rivaled the Spitfire IX and P-51B in speed and climb. But the -93 in a P-39 was not to be, probably because the Army didn't want the Russians to have it. They were the main customer for the P-39 at the time.

Could you possibly expand on the comment about the Army not wanting the Russians to have that -93 power plant? Thanks, Hansie

 

[tomo pauk]

...
Now there WAS a two stage mechanical Allison, the first production model was the V-1710-93 for the P-63. It featured a separate second stage supercharger driven by a jackshaft from the Allison starter dog that drove through a hydraulic clutch that automatically regulated manifold pressure. The -93 developed 1325HP for takeoff and 1180HP at 21500' with 1825HP war emergency. This pushed the P-63 without wing guns to 422mph at 24000'. They bolted a comparable model onto a P-40 and called it the Q and even that old P-40 went 418mph at 24000' and climbed like a rocket. Only 3 of those Q's were built.

This is one of better post in this thread. Some nitpicks:
- P-63A, even when using water injection was barely able to beat 400 mph mark; P63C, with a bit better engine might go beyond 420
- 1800++ HP was available under 5000 ft

More importantly the -93 was in full production in April 1943 and the P-63 didn't fly until October. Why in the world didn't the Army just put one in the P-39? It fit into the experimental P-39E. The contemporary P-39 model was the P-39N at 7650#. Add the 200# auxiliary stage and balance the weight with a larger 4 blade propeller and you have a real hot rod at 8050#. By July 1943 these P-39s would be coming off the production line and would have rivaled the Spitfire IX and P-51B in speed and climb. But the -93 in a P-39 was not to be, probably because the Army didn't want the Russians to have it. They were the main customer for the P-39 at the time.

Russians did have P-63s, ergo they got the -93s. A 2-stage V-1710 as-is will be very tricky to install on the P-39, if not impossible.
Ceterum censeo - if there is a real surplus of the 2-stage V-1710s, the P-51 is your platform.

 

[P-39 Expert]

Ah, for a P-39 expert you are making a number of mistakes.
P-39E was originally designed for the infamous Continental O/IV/V-1410 which was considerably longer than the Allison engine. With no airworth examples of the Continental engine available (or likely to be) in 1942 the design was altered to take the two stage Allison. the fuselage was 1.75 feet longer than the standard P-39s. One of them weighed in at 8918lbs (some sources say they were nicknamed the "lead sled") P-39E also had a bigger wing. Relationship of wing to engine/fuselage may also be different
View attachment 487046
Notice where the door is compared to a normal P-39?
Auxiliary supercharger is right about where the oil tank is on a normal P-39.

The P-40Q was hardly a lightweight at 9000lbs when using the V-1710-121 engine, full internal fuel and four guns and ballast to represent 235rpg.
in an early test it using a V-1710-101 engine weighed 8203 lbs with 160 gallons of fuel which leaves us wondering what was left out.

The fuselage was indeed lengthened by 1.75' but that was their solution to the extra 200# from the auxiliary stage supercharger. Adding 200# aft of the CG necessitated moving the wing back a little for balance, then the tail had to be moved back to preserve the distance from the CG to the tail for the same leverage. That is why the front cockpit door edge is before the wing leading edge (same as the P-63) while the normal P-39 front door edge is right about even with the wing leading edge. They moved the wing back.

Now is where I differ from what you have read. The engine compartment for the P-39E and the P-63 was still exactly the same size as the P-39. The distance from the front edge of the engine compartment (right before the exhaust stacks at the cockpit turnover structure) and the back bulkhead (almost to the back edge of the carb inlet scoop, you can see the panel edges) is EXACTLY the same. In a normal P-39 that compartment contained (going aft) the engine, coolant tank, then the bulkhead and after that the oil tank. In the P-39E and the P-63 they moved the coolant tank up right behind the cockpit on the right side and put the auxiliary stage behind the engine where the coolant tank was. That area was exactly the same size on the P-39, P-39E and P-63. So the fuselage was lengthened but it was lengthened aft of the engine compartment, not to make room for the auxiliary stage. Now that's not what you read, but that is what happened.

In my opinion it would have been easier to keep the original P-39 dimensions, add the auxiliary stage where the coolant tank had been, and offset the 200# extra weight aft of the CG by installing a larger (heavier) four blade propeller. Notice the E had a three blade propeller because a four blade propeller was not available at the time. That four blade propeller would have helped tremendously at high altitude. Additional balance adjustments could come (if needed) from moving the radios up from the tailcone to right behind the cockpit (you see this in photos all the time) or adding more armor plate right behind the propeller. But the Army had already decided that the P-63 would be balanced by moving the wing back and lengthening the tail cone so that's the way they did it on the P-63's predecessor, the P-39E.

Would have had a two stage P-39 in mid 1943.

 

[P-39 Expert]

This is one of better post in this thread. Some nitpicks:
- P-63A, even when using water injection was barely able to beat 400 mph mark; P63C, with a bit better engine might go beyond 420
- 1800++ HP was available under 5000 ft



Russians did have P-63s, ergo they got the -93s. A 2-stage V-1710 as-is will be very tricky to install on the P-39, if not impossible.
Ceterum censeo - if there is a real surplus of the 2-stage V-1710s, the P-51 is your platform.

Graphs and tests in wwiiaircraftperformance show a P-63A doing 422mph without wing gun drag. I agree that the -93 would have worked well in a P-51, the -J model was just too late for WWII.

 

[pbehn]

When discussing the success of pilots in P-39s on the eastern front is there any truth at all in the rumours that they were in many cases, late in the war flying P-63s. Since there was an agreement that this wouldn't happen, Soviet records would try to hide it.

Wiki isn't a great resource but says this

By a 1943 agreement, P-63s were disallowed for Soviet use against Germany and were supposed to be concentrated in the Soviet Far East for an eventual attack on Japan.[citation needed] However, there are many unconfirmed reports from both the Soviet and German side that P-63s did indeed see service against the Luftwaffe. Most notably, one of Pokryshkin's pilots reports in his memoirs published in the 1990s that the entire 4th Guards Fighter Aviation Regiment (4 GvIAP) was secretly converted to P-63s in 1944, while officially still flying P-39s. One account states they were in action at Königsberg, in Poland and in the final assault on Berlin. There are German reports of P-63s shot down by both fighters and flak. Hans Rudel, highest decorated pilot of the Luftwaffe, states in his memoirs, "We often encounter American types of aircraft, especially Airacobras, Kingcobras and Bostons." This was in the Courland front towards the end of the war. [15] Nevertheless, all Soviet records show nothing but P-39s used against Germany.[citation needed]

In general, official Soviet histories played down the role of Lend-Lease supplied aircraft in favor of local designs, but it is known that the P-63 was a successful fighter aircraft in Soviet service. A common Western misconception is that the Bell fighters were used as ground attack aircraft.

 

[Milosh]

Deliveries of production P-63As began in October 1943. The USAAF concluded the Kingcobra was inferior to the Mustang, and declined to order larger quantities.

And, the P-63 was well behind what would be coming off the NAA production line > the P-51H.

 

[drgondog]

Graphs and tests in wwiiaircraftperformance show a P-63A doing 422mph without wing gun drag. I agree that the -93 would have worked well in a P-51, the -J model was just too late for WWII.

To quote an unknown Southern sage, circa 1864 "If a frog had a glass ass, it will only hop once"

If you peruse the AAF Flight Test reports and peel to the summary - Operational Suitability, May 1944. The Eglin Test pilots conclude that the P-63A 'cannot be considered in current form to be an operationally suitable aircraft at this time".

Neither the Allison V-1710-119 for the XP-51J, nor the 1710-143/-145 ever attained reliable HP output to specifications for Boost over 61". NAA quickly lost interest in the XP-51F due to the plague of engine related issues not solved by Allison. After the AAF forced NAA to install the -143/-145 to replace the 1650-11 and -21 after the XP-82/P-82B series, the Allisons effectively castrated the P/F-82 E/F/G.

The Net-Net is that the P-63 with a fully functional Allison 'two-stage', enhanced structural aft section, aileron trim tables, changing hor.stab' incidence to eliminate stick reversals in high speed dives, stiffening the elevator rib distribution to prevent elevator ballooning/rupture in high speed dives plus heavy controls and instability at high speeds - it was deemed 'fun to fly with excellent maneuverability'.

That said, at the Patuxent Fighter Conference in October, 1944, it was one of the lowest ranked fighter in the Conference in the category 'Best above 25K', 'Best below 25K' (both <1%), -------> highest rank 'Best Strafer, #8 at 2%, 'Best stability in a dive #7 at 4%,

The kindest remark was 'this is what the P-39 should have been'

 

[Shortround6]

Graphs and tests in wwiiaircraftperformance show a P-63A doing 422mph without wing gun drag. I agree that the -93 would have worked well in a P-51, the -J model was just too late for WWII.

Not only lacking wing gun drag, lacking around 1000lbs of weight compared to a service P-63.
The graphs give no description of the aircraft involved.

I also love the part in an earlier post about the V-1793 being in full production in May of 1943.
May of 1943 saw the engine fully prepared for the model test, which was not actually fully completed until Nov 27th 1943. Yes engines had been built, delivered and were flying in P-63s before Nov 27th but after that date the engines were released for unrestricted use. Except the WER rating test was done in Dec of 1943 so any fantasies of P-63s or Super Allison Mustangs flying around with 1800hp at sea level engines need a reality check. Especially considering that the long development time included modified pistons and piston rings to stand up to the water injection and extra power.

 

[wuzak]

Wrong book. Park wrote two books about his tour in New Guinea. "Nanette" was a fictional account based on all the stories he had heard and participated in. His second book, "Angels Twenty" was a nonfiction (factual) account of his tour from December '42. He says he got his P-39N in December in the nonfiction work. Both books are worth your time, very entertaining and provide a day to day look at the perils of WWII in that area.

But "Nanette" was the nickname of his P-39 in real service, and it looks like it was squadron code N. And I never mentioned a book.