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That I'm aware of, but that doesn't seem to apply with aircraft design as the structures are mostly hollow. I was curious if there were any rules of thumb.For a solid object the weight goes up with the cube of the increase.
That I'm aware of, but that doesn't seem to apply with aircraft design as the structures are mostly hollow. I was curious if there were any rules of thumb.
For a solid object the weight goes up with the cube of the increase.
Double the length (or caliber of a shell) and the weight goes up 8 times.
Of course for hollow objects this becomes less accurate real quick.
Also aircraft, for the most part, don't scale up in perfect proportion. Adding 20% to a fuselage length rarely means adding 20% to it's width and/or 20% it's depth/height.
That I'm aware of, but that doesn't seem to apply with aircraft design as the structures are mostly hollow. I was curious if there were any rules of thumb.
Well, technically the B-52A was 420000 if I recall. This seems only valid if I was to make comparisons between aircraft of similar structural strengths.The North American B-45 was:
75 ft long, 89 foot span, 91,000 lbs max weight
The Boeing B-52 was:
159 feet long (about twice), 185 foot span (about twice), 488,000 max gross (about 5.3 times, not quite cube or it would be 8 times). But, it is close to cube.
I'll start looking through statisticsYou might try a few yourself. Interesting question.
I believe lift increases with the square of wing area, so if the scale is 2 the lift increases by 4.
I believe lift increases with the square of wing area, so if the scale is 2 the lift increases by 4. But weight increases by 8.
I would have figured that the Vulcan was rated for 3.5g normal and the F4D was probably rated for 6.0-6.5 or so normal. Wouldn't everything only scale right if the aircraft had similar strength?We might have a good look at it using the F4D Skyray and the Vulcan bomber, though. Hard to say without doing it and not my premise.
I'm not sure if this has any validity or not as it relates to aircraft weight or what you said about wing-loading.A more generic look will tend to show that wing loading does tend to increase with size, which tends to be compensated for by increasingly complex high-lift devices. One doesn't put triple-slotted Fowlers and leading edge flaps on something the size of a Foxjet, but would on a 747.
Now that's interesting, especially with Reynolds numbers I'd have figured lift figures would be better when smaller...Builder 2010 said:The one thing that doesn't scale well when you go smaller, i.e., making a scale flying model, is the speed at which is flies. Air molecules are a fixed size so the amount of them passing over and under the airfoil doesn't scale.
That's interesting, I'd have figured that if the bird's weight went up to the cube of size, that the wing area would go up to the square root and it'd be actually worse. With scaling not necessarily working in that order, the issue is how much the bird's body scales up versus how big the wings get.To get lift in a small model wing, especially if it is heavily loaded, requires faster air flow across the surface. This is specifically why small birds have to flap their wings so much faster than large birds.
According toThe B-17 cruised at 187 mph.
Now that is interesting, though I vaguely remember something about stalling being easier to trigger at low Reynolds numbers (which is strange, I'd figure more turbulent flow...)In scale RC model meets some of the judges are wanting the planes to fly at scale speeds too. So for the 1:16 B-17 I built the scale speed would be a bit under 12mph. Instead the model flew at about 80mph. At 12mph the wing has literally no lift at all. When model design aircraft are tested in wind tunnels, the air velocity is increased to simulate the Reynolds number of the air over the actual wing.
There is, and it is a man with 10 hand thumbs and another 10 foot thumbs knows all the rules.Clearly there isn't.