alejandro_
Airman 1st Class
- 281
- Jul 4, 2005
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We (the museum) fly a Mitsubishi A6M5 Model 52 Zero and we have some original design documents and the original designer helped with the restoration back in 1977 or so. It is stressed to a 6 g limit, but has a 100% safety factor, so the ultimate fail point is supposed to be at or above 12 g.
To get 1,500 HP modern fighter performance from the Zero with 1,180 hp in its most powerful variant, the Zero sacrificed armor and self-sealing tanks. As a result, it would burn much more readily and the pilot has but little protection.
Comparing dissimilar planes really confuses things as what you are trying to compare is structural weight and not empty weight.
SR - I rarely disagree with your posts. That said I will offer some thoughts based on only a sample of the two airframe companies I have worked for plus one as a contractor - in the airframe structures group. The primary disagreement is that All structural weight plus mission requirements for fuel, bombs, ammo, munchkins go into Mission Gross Weight - for analysis.
More comments below
Structural weight would include the wing, the fuselage (but NOT cowl) and tail surfaces, both horizontal and vertical.
Engine, prop, landing gear and even control runs and cockpit fixtures don't do anything for strength.
Landing gear does nothing for aircraft strength and engine weights can vary considerable.
In the F6F comparison the R-2800 engine weighs 2480lbs while the Sakae engine in the Zero weighs about 1300lbs. Propellers are somewhat in proportion. F6F needs larger heavier landing gear just to hold up the engine and prop while taxiing
Not to mention the extra almost 100 sq ft of wing on the F6F.
Thick wings could weigh less than thin wings of the same size because the thick wing section resisted bending better.
Even if you can find two fighters of similar wing area and using similar weight engines it can be difficult to estimate structural weight.
The Curtiss Hawk gained about 250lbs in the wing alone from the P-36 to the later P-40s. Now the later P-40s may have been more resistant to combat damage than the P-36 but the wing had to be beefed up to handle the the 8 "G" service load (12 "G" ultimate) as the plane gained around 2000lbs of gross weight. A P-36 wing would be a bit suspect on a P-40 as 8 "G"s at 6000lbs is equal to 6 "G"s at 8000lbs and while 8 "G" is rarely seen by service fighters 6 "G"s is all too close to the normal flight envelop.
DD how is yield measured on aircraft materials? For steels in oil industry it is normally a total extension under load (o.5%) for alloys and high temperature steels it is normally 0.2% or 0.3% "offset".
In many debates the issue of aircraft strength appears. In WW2 there were some aircraft that had a reputation for strength P-40, P-47, Yaks while others were seen as nimble (Ki-43, A6M). I would like to know a few opinions on what is the best criterion to determine aircraft strength, focusing on the airframe and how resistant it is to damage. Most people seem to use empty weight of the aircraft. I wonder if other parameters could be included, like G limits or construction features.