Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: GENRLX on May 08, 2004, 10:12:45 AM
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Yes, it was a prototype. It did fly,however too late to be of any service. It flew on the day b4 Hiroshima for one flight, killing the pilot I belive.
Max speed: 466mph@28,545ft.
ceiling: 39,370ft
Engine: 18 cyl. air-cooled radial @ 2,130hp
weight: 10,854 lbs
armament: 4x30mm and 264lbs bombs
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I have read that an aerodynamic study of the Shinden indicated that it would be even more unstable than the Curtiss XP-55. Likewise, the projected speed of 466 mph was deemed pie-in-the-sky wishful thinking. If the Curtiss XP-55 example is any indicator, speed would be no better that contemporary Japanese fighters. Curtiss projected 507 mph on 2,200 hp. However, that engine (P&W X-1800) proved a bear to develop and the Allison installed in the interim proved no faster than 378 mph. Eventually, the X-1800 program was canceled and the XP-55 proved to be unneccesary (not to mention a long way from viable).
I figure that the Shinden was a full year from being properly sorted, assuming such development was not thwarted by the war. I am also convinced that it would never come close to projected performance either (based upon previous examples of Japanese fighters developed during war time). That it was rushed into production only illustrates the utter desperation of the Japanese in 1945.
My regards,
Widewing
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what I don't understand is which benefits did the "inverted" "tail-first" configuration had over the "standard" one...
All I can think about that configuration are drawbacks...
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INCREDIBLE MANUEVERABILITY, even at high speed and E.
Also more unstable, but if you want to fly stable aircraft, stick to a Cessna.
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Any reason why it's so much more maneouverable?. I can find just one reason why such a plane could be better in that department than a "normal" plane (very different CoG placement than in a standard configuration, which also could cause that unstability, am I right?)....
And the pusher propeller was a definite disadvantage. A prop turning into a turbulent flow, such as the one present behind a fuselage, loses a lot of efficiency and should cause severe vibration. Thus, you are wasting a lot of engine power for nothing, and your plane might be quite unconfortable to fly...to say the least.
Unless someone gives me some in-sight on the properties of this configuration and the other possible advantages it held, I stay quite sceptical about it.
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Originally posted by RRAM
Any reason why it's so much more maneouverable?. I can find just one reason why such a plane could be better in that department than a "normal" plane (very different CoG placement than in a standard configuration, which also could cause that unstability, am I right?)....
And the pusher propeller was a definite disadvantage. A prop turning into a turbulent flow, such as the one present behind a fuselage, loses a lot of efficiency and should cause severe vibration. Thus, you are wasting a lot of engine power for nothing, and your plane might be quite unconfortable to fly...to say the least.
Unless someone gives me some in-sight on the properties of this configuration and the other possible advantages it held, I stay quite sceptical about it.
Read about the test flight of the DO-335 from Capt Brown.
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Originally posted by WHATTHEHELL
Read about the test flight of the DO-335 from Capt Brown.
the Do-335 had two engines, one pusher, other puller. The after propeller was known to have a quite low efficiency. However, you can afford losing some of the efficiency of the after engine if the configuration allows for a good deal of efficiency in other departments.
The Do-335 did allow for that efficiency, was a two-engined aircraft with much less roll inertia that any other twin engined plane, and allowed for a two-engine configuration with much less drag than the others (to the point that the reduction of drag more than compensated for the loss of eficiency of the aft propeller). Not to mention the engines rotation pretty much gave the plane no torque effects at all.
The vibration problems required some tweaking but after 2 years of testing of prototypes they were quite solved. The Shinden never had that development time.
In short:there were a lot of benefits from the configuration, one of them making good the loss of eficciency of the after propeller. It was a SOUND configuration.
The shinden was an one-engined plane, which wasted a lot of engine power, had vibration problems that could be solved with enough development time (time the model never had because it was rushed into production before time), and in short, had more drawbacks than benefits.
While the Do-335 pusher-puller configuration was a sound one, the Shinden one wasn't. At least from my point of view and from what I know at this point... I repeat that there may be something I don't know about this configuration that makes it worthy. That's why I asked about those possible benefits in the first place ;).
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Please add this plane.
And with it add the F8F, F7F, Do 335, Go 229, P-80 and a whole bunch of others. Then change the name from Aces High to Final Fantasy MCMXLVI.
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Canard configuration produces a more maneuverable aircraft because of the orientation of the CG, also the tail moment is much shorter. These do make the aircraft more unstable but instability is a desired quality in a fighter plane, to a point.
As far as the pusher prop theory, I couldn't say, but I'm sure that problem, if real, would've been solved in the early stages of developement. Perhaps thru the utilization of counter-rotating props.
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Originally posted by GENRLX
As far as the pusher prop theory, I couldn't say, but I'm sure that problem, if real, would've been solved in the early stages of developement. Perhaps thru the utilization of counter-rotating props.
how do contra-rotating propellers, spinning in the middle of a turbulent stream of air, solve the vibration and efficiency problems associated with a single pusher propeller?. Because from my limited knowledge, if anything,they would worsen them...instead of having ONE propeller turning there, you get TWO...
doesn't sound too well for me.
BTW, both problems (efficiency loss and vibration) are well known and real. You can see a good example if you look at single-propelled merchant ships. They have just one central propeller spinning in the middle of the turbulence caused by the hull. The propeller losses a lot of efficiency because of that, and the vibrations are quite severe...and audible (guess why do those ship sound like "THUD-THUD-THUD-THUD"?. Well, you've just found the reason :))
BTW thanks for the info on why did the canard configuration help the maneuvering...as I firstly thought it was directly related with the CoG change.
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How were the problems associated with a pusher-prop design overcome in today's canard type aircraft? I'm sure it's not an insurmountable obstacle.
The configuration also allows for the armament to be placed in the nose of the aircraft keeping the weight along the axis of the fuselage thus increasing its' roll rate and stability in a roll.
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Originally posted by GENRLX
How were the problems associated with a pusher-prop design overcome in today's canard type aircraft? I'm sure it's not an insurmountable obstacle.
today's aircraft are mostly jets...those have no propellers ;).
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Was the B-36 with its multiple pusher props in-efficent?
A canard is very hard to stall(as when landing), from what I have read.
Are not the E-Z a/c, pusher canards?
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The canard also has trouble in placing conventional flaps systems - as the main wings are more often than not located behind the center of gravity.
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Originally posted by MiloMorai
Was the B-36 with its multiple pusher props in-efficent?
It's not exactly the same to set a pusher prop behind a wing...
than behind a FUSELAGE ;). Guess where's the air flow more turbulent...
in any case the B-36 pusher prop configuration was because another compromise. Pusher propellers allowed for much more aerodynamic placement of the engines on the wing. I don't know for sure, but I guess that the reduction in drag more than compensated for the reduction because the lower propeller efficiency, which would be there (even in a lower level than in a propeller behind a fuselage).
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Originally posted by Mathman
Please add this plane.
And with it add the F8F, F7F, Do 335, Go 229, P-80 and a whole bunch of others. Then change the name from Aces High to Final Fantasy MCMXLVI.
You sir, are a frikking genius. I'd play.
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Pusher prop is in a turbulent stream from the fuselage which causes some propeller efficiency loss.
In a tractor configuration the fuselage is in the propwash which results in some drag increase over a fuselage in the clean laminar flow afforded by the pusher configuration.
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The Italians had the pusher canard, the SAI(Ambrosini)SS4. On its second flight it crashed(Mar 8 1939).
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If you're talking commercial and military yes, today most aircraft are jets. If you could grasp the context of the subject, you would have realized that canard aircraft today are primarily found in GA or EAA. This is the area of developement where canard properties are explored.
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Originally posted by RRAM
the Do-335 had two engines, one pusher, other puller. The after propeller was known to have a quite low efficiency.
The Do 335 actually was, according to British test pilot Eric Brown, "measurably faster" on the rear engine alone than on the front engine alone. Dornier planned developments of the Do 335 with the rear engine only, in some cases with the addition of jet engines.
The pusher configuration turned out to be the more efficient one, despite the disadvantage of disturbed flow entering the propeller disc. Hence the willingness of the USAAC to experiment with it in the R-40C competition (which produced the XP-54, XP-55, and XP-56), all pushers, and the later XB-42 bomber. Hence also the German preference for pushers in what was intended to be their last generation of propeller fighters. However, technically pushers tend to be hard, requiring very stiff aft fuselages, long extension shafts, or rigid tail booms, and problems such as ensuring sufficient cooling on the ground and a safe way for the pilot to leave the cockpit in an emergency are serious. The R-40C program was plagued by engine troubles and the Germans did not have any more luck. Often the additional weight of the configuration defeats the aerodynamic advantages.
The canard configuration was also the more efficient one. On a conventional stable aircraft, with the c.g. in front of the center of lift, the tailplane gives a download, which has to be counteracted by additional lift from the wing, all at the cost of extra drag. (Which is why unstable or marginally designs are popular now, even for airliners.) The canard surface has the advantage that it can balance the aircraft whilst generating lift. The potential disadvantages are instability -- if the angle of incidence increases, the AoA of the canard also increases, so to the nose raises even more -- and a tendency to stall much easier than a tailplane, because the canard has a positive angle of incidence. The stall characteristics of the XP-55 were quite bad.
Manoeuverability probably doesn't enter much into it, with WWII aerodynamics. Modern canarded fighters use vortices from the canards to 'energize' the flow over the wings, but this was beyond the aerodynamics of 1945. Having a better lift/drag ratio would have been useful, though.