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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.
...
Not so fast Elmas I have seen the Mx MCLMXXXIV version in "Star Wars" and it turned out to be a world beaterAmateurs 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…
Great post Elmas, but knowledge of washout couldn't just be just held in Germany, the Spitfire flew with it in 1936.
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.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.
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 AllisonsI 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…
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.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.
Could you possibly expand on the comment about the Army not wanting the Russians to have that -93 power plant? Thanks, HansieJust 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.
...
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.
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.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.
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.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.
Not only lacking wing gun drag, lacking around 1000lbs of weight compared to a service P-63.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.
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.