Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: fdiron on February 08, 2002, 02:47:49 AM
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The P39, with its engine behind the pilot, had a very streamlined shape. This also allowed the P39 to have a 37mm cannon mounted in the nose. Why didnt other U.S. fighters have their engines placed behind the pilot? It seems this would have many advantages such as lower drag and better aiming for weapons. It could also possibly protect the engine for hostile fire. If the engine was mounted over the center of gravity I dont see any negative effects of this arrangement.
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Well the P39 was reported to have a very poor stability just because of the problems that were introduced with placing the engine in the back.
Combined with underpowered engine and very unreliable 37mm cannon it made the airacobra a deathtrap for many pilots.
Finns fought succesfully against P39's in brewsters (you know, the ones that were put to training use by U.S. navy after first encounter with a6m and 13 out of 16 lost..)
I've read that the pilots respected the awesome firepower but didn't consider the plane much of a threat because it could be outmanouvered easily.
Strangely the same was said about hurricane and spitfire - the top finnish ace described them as 'clumsy, stiff and horribly slow below 3km altitudes.'
and
'hurricane is the easyest to kill in a turnfight, try to fool him into turning so he is easy to kill. Just a short spray in the front of the plane usually sets it to fire from the first hit.'
That doesn't sound at all like the spits and hurri we have here (except the slow part..) I wonder what kind of beast the brewster was.. :)
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Actually I suspect the issue is more pilot related than anything else hehe.
Did the commies have any good pilots btw?
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Of course they had a few aces also but mostly the pilot quality was low. Judging from what I read anyway..
Uncle Stalin was kind enough to execute most of the talent of the military before the war so there were many newbies both in leadership and crew.
They had nice numbers though, about 10:1 I think. Sometimes the bombers came in near thousand figures while we had maybe 20 fighters to protect :)
That ofcourse lead to amazing stories, like one that happened over my home city. A finnish pilot made the worldrecord of shooting down 6 enemies in about 30 seconds (bombers.)
He then had to rtb because he had spent all his ammo.
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And that was with a Fokker D.XXI if I recall right?
// fats
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That might have been, I don't recall any more details of that.
I do recall of the pilot saying he used crude caliber mg's so it might have been fokker.
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Rolls Royce planned to make a experimental Mustang version with a RR Griffon mounted like in the P-39. The project reached mock up stage. Estimated performance was something like near 800km/h at high altitude.
IIRC Sarvanto's case was 6 DB-3s in 4 minutes with the D.XXI. There might have been other similar cases later.
gripen
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http://www.elknet.pl/acestory/sarvan/sarvan.htm
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Why didnt other U.S. fighters have their engines placed behind the pilot?
Putting the engine behind the pilot is not a good thing by itself.
- It moves the CG of the aircraft towards the rear which reduces stability. The only way to restore stabiity is to put a bunch of weight in the nose.
- The aft engine location increases weight and cost and complexity. A drive shaft system is required, which in the case of the P-39 was quite heavy, took a lot of time and money to develop, added one more critical system that could fail and would require time and money for maintenance.
So if a rear engine sucks, why did they put the engine in the rear on the P-39? Because the plane was designed around the huge 37 mm cannon. It was too big to fit in the wings and the only way to fit it into the nose of such a small fighter was by moving the engine somewhere else.
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Originally posted by funkedup
So if a rear engine sucks, why did they put the engine in the rear on the P-39? Because the plane was designed around the huge 37 mm cannon. It was too big to fit in the wings and the only way to fit it into the nose of such a small fighter was by moving the engine somewhere else.
Not exactly:
"The Bell P-39 Airacobra had its origin in June 1936 when the Buffalo, New York-based Bell Aircraft Corporation's design team, headed by Robert J. Woods and Harland M. Poyer, began the design of a single- seat fighter. The Bell corporation was responding to a 1936 Army Air Corps request for a new single-seat fighter design, one which would be equal to the new European fighters just then beginning to undergo flight test.
Woods and Poyer conceived the idea of mounting the engine in mid-fuselage, driving the propeller via a ten-foot extension shaft. Such an arrangement was not exactly new, having been tried earlier by the experimental Westland F.7/30 biplane and by the Dutch Koolhoven F.K.55 monoplane. Among the potential advantages offered by such an arrangement was the possibility of superior maneuverability, since the weight of the plane would be more nearly concentrated at the center of gravity. In addition, it would facilitate the installation of a heavy nose armament, since the armament could be mounted near the centerline, minimizing the effects of recoil forces. It would also offer good visibility for the pilot, and would permit the installation of a tricycle undercarriage.
Bell's original proposal was to place the pilot behind the engine, forcing the cockpit very far to the rear and making the proposed aircraft look a lot like the Curtiss XP-37. A mockup with this configuration was built with this configuration and was given the company designation Bell Model 3. However, the problem of visibility over the engine eventually forced Bell engineers to move the pilot ahead of the engine, and a revised mockup, given the company designation Bell Model 4, was used as the basis of a formal submission to the USAAC on May 18, 1937. The Bell submission promised a top speed of 400 mph at 20,000 feet and a gross weight of only 5500 pounds."
- from Joe Baugher's P-39 article
Full article at http://home.att.net/~jbaugher1/p39.html
-Smut
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P39 versus 109G2 story and more at http://www.elknet.pl/acestory/juuti/juuti2.htm
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It excelled in the low-altitude strike role and the 37-mm nose cannon made the Airacobra an excellent tank buster. When operating at low altitudes, the Airacobra was often able to hold its own against German fighters.
Some Soviet pilots felt that the P-39 outclassed even the Messerschmitt Bf 109 and Focke Wulf FW 190 at altitudes below 10,000 feet. Several Soviet Airacobra aces are known. Lieutenant Colonel of the Guards Alexander I. Pokryshin, a Soviet ace with 59 kills to his credit, scored 48 of these in a P-39. He was awarded the Distinguished Flying Cross by President Roosevelt. There are eight other P-39 pilots with at least 20 kills. The four after Pokryshin were Captain G. A. Rechkalov with 44 kills, Captain N. G. Guliav with 36 kills, and the Klinka brothers Major G. P. Klinka with (text lost)
http://home.att.net/~jbaugher1/p39_19.html
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I bet the P39 would have been a good fighter had it had a merlin engine and a supercharger.
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You guys give the merlin toooooo much credit compared to the allison...the problem with the allison was the US Army...
I you look at time lines the allison has many firsts...
A few wing commanders cited the 1942 P-51A's allison with remarkable ability to come home on ruined bearings whilst the merlins were too sensitive and prone to seizing more often..the allison could be coaxed beyond its safe limits and be forgiving...
I the boys had Shaw's book they would have cleaned up against the zeros in 1942....
I'd love to have the P-39 with the turbo in 1942....so about 375 to 380 at 20000ft..low altitude performance would suffer though....
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I read in some book, I have forgotten the title, that the Allison engines never did catch up with the Merlin engines for high altitude performance.
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We have to assume that the traditional front-engine layout was best for single-engined fighters, simply because nothing else tried worked as well.
However, for certain specific purposes, other layouts might have worked better. The P-39/63 was an interesting attempt, but I would have like to have seen a twin-tailboom pusher. Various examples of this were tried, but I think only the Swedish SAAB 21 made it into significant service, and that wasn't a particularly wonderful design.
The advantages of such a design ( unlike the SAAB, I am assuming a forward cockpit with gun actions/ammo storage behind the cockpit, and the gun barrels running underneath or to one side - think DH Vampire with a piston engine) include:
1) Excellent forward/downward visibility (particularly useful in ground attack or carrier planes)
2) Concentration of heavy armament in the nose without the penalties of synchronisation.
3) The possibility of mounting one heavy cannon in the nose for anti-tank purposes (possibly with the barrel running through the cockpit - all sorts of Freudian advantages here:) )
4) It would need a tricycle undercarriage, greatly improving forward visibility on take-off and landing (particularly useful in naval aircraft, or in close-support planes which need to use small forward airstrips - both of which also call for a tough, long-stroke undercarriage).
5) Variable weights (ammo and fuel) could be concentrated over the wing so the handling wouldn't be affected as they were used up (a problem for the P-39 with its forward ammo supply).
6) The engine (preferably an air-cooled radial) would provide a lot of added protection for the pilot from the most dangerous zone of attack - the rear.
Disadvantages?
1) Not too comfortable to bale out of (an ejector seat, or an explosive charge to blow off the prop, would be required).
2) Not too comfortable to crash into anything in a bad landing - the engine might end up in your lap, having passed through the rest of you....
3) Handling might not have been as good as a conventional fighter, although I don't think enough designs with this layout were tested to reach any definitive conclusions.
So, you could have ended up with a plane in two versions; a carrier-borne fighter-bomber, and an armoured ground attack/anti-tank fighter-bomber. It might have been a useful addition....
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/
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ahhh Tony this is what you want
http://www.aeroflight.co.uk/profile/d335hist.htm
:)
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I've heard that the Do335 is the fastest piston engine production aircraft in the world. Now I think the world record for the fastest prop aircraft is held by a highly modified Tempest.
The U.S. used some mid and rear fuselauge mounted engine aircraft in the Vietnam War. These were not high performance planes though.
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Originally posted by RightF00T
ahhh Tony this is what you want
http://www.aeroflight.co.uk/profile/d335hist.htm
:)
No, definitely not - the Do 335 was a horrible plane! It had all of the disadvantages of a front-engined in terms of visibility and gun mounting, plus the disadvantages of a rear-engined plane! It had to be made very big because the fuel had to packed into the fuselage as well as two engines, a pilot and most of the armament.
If I wanted a heavy fighter, I would have chosen the DH Hornet - beauty versus the beast. The drag disadvantage of a conventional twin layout obviously wasn't that great as it could still manage around 470 mph...
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/
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Hi Tony,
>If I wanted a heavy fighter, I would have chosen the DH Hornet - beauty versus the beast. The drag disadvantage of a conventional twin layout obviously wasn't that great as it could still manage around 470 mph...
Twin-engined fighters were known for a poor search view due to the engine nacelles blocking much of the view. With the pilot being located far behind the propeller disks, the Hornet certainly was affected by this.
The Hornet achieved its speed on 4120 HP, by the way, while the Do 335 only required 3500 HP for the same speed. With later, more powerful engines of the DB603 series, the Dornier would have been even faster.
Here's what Eric Brown of the RAE had to say about the Do 335 (from "Wings of the Luftwaffe"):
"The combination of features embodied by the Do 335 Pfeil rendered it unique at the time of its birth and it was destined to remain so, but had the Dornier warplane not appeared at the tailend of the piston-engined fighter era it is more than likely that its configuration would have been plagiarised."
Regards,
Henning (HoHun)
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Originally posted by HoHun
Hi Tony,
Here's what Eric Brown of the RAE had to say about the Do 335 (from "Wings of the Luftwaffe"):
"The combination of features embodied by the Do 335 Pfeil rendered it unique at the time of its birth and it was destined to remain so, but had the Dornier warplane not appeared at the tailend of the piston-engined fighter era it is more than likely that its configuration would have been plagiarised."
I have my doubts about that; I think that the layout was just too inconvenient. If more power was wanted, then other nations usually just fitted a bigger single engine. I don't know of any plans for a Do 335 look-alike.
I think a better twin-engine solution was the one used by the Douglas Mixmaster bomber, with two engines in the rear fuselage driving pusher props. This left the nose clear for a good view, armament etc.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/
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Hi Tony,
>If more power was wanted, then other nations usually just fitted a bigger single engine.
How many 3500 HP engines were there in 1944? :-)
>I think a better twin-engine solution was the one used by the Douglas Mixmaster bomber, with two engines in the rear fuselage driving pusher props.
Dornier documents indicate that they were thinking along the same lines - project P. 252 outlined an aircraft of just that layout. However, while the Do 335 was ready (and displayed top-notch perfomance) in 1945, P. 252 would have required quite a bit more development time.
Regards,
Henning (HoHun)
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Originally posted by HoHun
Hi Tony,
>If more power was wanted, then other nations usually just fitted a bigger single engine.
How many 3500 HP engines were there in 1944? :-)
Not quite that simple, Henning, as you well know! The penalties associated with two engines (even for the Do 335, you still have the extra weight plus the aft prop losing efficiency through working in air disturbed by the front prop) means that you could design a single-engine fighter with the same overall performance as the Do 335 on a lot less power.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/
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Hi Tony,
The Do 335's high speed shows it was ahead of all other propeller-driven fighters at the contemporary level of engine technology. Its performance was only matched by later designs with advanced engines that resulted from additional development time. It was an exceptional design that could have competed with every other piston-engined fighter on an equal level of technology.
However, the era of the piston-engined fighter had just ended with the advent of the jet fighter.
Regards,
Henning (HoHun)
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There were contemporary fighters at the same stage of development in other countries that had the similar speed performance plus equal or better climb, maneuverability, range, and load carrying capacity. Gimme an F7F or P-47N or F4U-4 or P-51H any ole day of the week. :)
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Wouldnt mounting 2 englines in the fuselauge eliminate the drag penalities that an aircraft with engines on the wings had?
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Originally posted by fdiron
Wouldnt mounting 2 englines in the fuselauge eliminate the drag penalities that an aircraft with engines on the wings had?
That was the whole idea, and it worked to that extent. There were penalties associated with this solution, however, as indicated in earlier posts.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine
guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/
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Hi Funked,
>There were contemporary fighters at the same stage of development in other countries that had the similar speed performance plus equal or better climb, maneuverability, range, and load carrying capacity.
The corner parameters of the Dornier Do 335 were about 600 km/h at sea level, 760 km/h at 6 - 7 km altitude, and roll-out of the first series aircraft in November 1944.
I don't think any of the other high-performance fighters matched this combination.
Regards,
Henning (HoHun)
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P-47N-1 were coming off the line in September 1944, P-47M were delivered in December. M and N were just as fast as the 335, although I think the 335 could climb better than the fuel-heavy N.
P-51H was capable of almost 490 mph, and was produced starting in January 1945. It could easily outclimb and outmaneuver the 335 as well.
F4U-4 and F7F were ~20 mph slower than Do 335 but superior in all other aspects, starting mass production in April and September 1944 respectively.
I agree that these aircraft all had better engines than the DB 603, but they were definitely contemporary designs. I think the most impressive thing about the 335 is that it was able to fly so fast with what was basically a dog of an engine. Compare it to the Me 410 and it's a hell of a machine.
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Originally posted by fdiron
The P39, with its engine behind the pilot, had a very streamlined shape. This also allowed the P39 to have a 37mm cannon mounted in the nose. Why didnt other U.S. fighters have their engines placed behind the pilot? It seems this would have many advantages such as lower drag and better aiming for weapons. It could also possibly protect the engine for hostile fire. If the engine was mounted over the center of gravity I dont see any negative effects of this arrangement.
Why dont you try and bail out of an aircraft with the props behind you....hmmmm....seems like just a slight problem:eek:
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Saab J21 (http://www.hotel.wineasy.se/ipms/stuff_eng_detail_j21.htm)
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I have read that the Do 335 suffered from propeller interface, I can understand what this means, but how did it affect this a/c. did it cause sever buffeting? adverse yaw? directional stability? mechanical failure? or was it just annoying like me?
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Hi Funked,
>I agree that these aircraft all had better engines than the DB 603, but they were definitely contemporary designs.
I think the key is speed over altitude. I don't have all the numbers, but my impression is that they all reached their top speed at higher altitudes than the Do 335, meaning that the latter was faster through much of the altitude band. The early DB603 engines admittedly had poor altitude performance, so I see your point about "better engines", too, but I think at medium altitude it was quite competetive.
>I think the most impressive thing about the 335 is that it was able to fly so fast with what was basically a dog of an engine.
Which by itself was a proof of the concept :-) To put your statement more positively, the DB603 had a lot of untapped development potential, and accordingly, the Do 335's speed would have risen further. Dornier also planned to install the more powerful Jumo 213 series engines into the aircraft, and if the Do 335 had had a higher priority, this certainly could have happened. (As it was, the promise of jet aircraft kept the Do 335 on low priority, and the Jumo 213 was reserved for aircraft already in mass production.)
In any case, though it doesn't fit the "historically significant", "mass produced" or "saw combat" criteria, I'd love to see the Do 335 modeled in Aces High just to see how it would match up. You're of course right that it was not a top performer in other respects, but speed is a great strength by itself. It certainly wouldn't be an arena dominator, but I think it would prove to be a very capable fighter nevertheless.
Its achilles heel - and here I'd agree with Tony - probably would be its poor view to the rear.
Regards,
Henning (HoHun)