lets hammer this out for once..

FlyingMonkey

Bought Another Trailer
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Of course part of the problem here is the definition of "better".

Wind has been brought up as a/the factor. But, things like what type of airframe, what is your flying goals, what is the pilot's skill level, none of these have been addressed.

What flight characteristics determine "better"?
 

earthsciteach

Moderator
Moderator
What if two swallows carried the coconut?

I've just skimmed through this, so may have missed many valid points and perhaps this one was already stated. I don't think the point is whether planes of equal size but differing weights will perform differently in wind. I believe that idea comes from a comparison of apples and oranges, to a certain degree. A larger, lightly wing loaded airplane will seem more controllable than a small, lightly wing loaded airplane. If nothing else, it has to do with inertia. A small plane will respond more quickly to control input than a larger plane. I describe it as feeling "twitchy."

A larger plane will not respond to the control as rapidly, so overcontrolling it is not as much of an issue. The inertia of the larger plane dampens its reactions to the control surfaces.

I think a lot of the thought behind the lighter/heavier debate comes from a comparison of, say, flying a Hobbyzone Champ in wind compared to a Bixler. Of course, the Champ is going to be horrible and get blown all over the place. It simply doesn't have the power to fight the wind. A Bixler is a blast to fly in the wind. It does get tossed around, but can easily overcome a 25-30 mph wind. At least, my Surfer with its upgraded motor can.

But, if I had to weigh in on the debate at hand, give me the lighter plane with enough power to fly against the wind. A heavier aircraft of equal size and power is probably going to have horrible wing loading.
 
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xuzme720

Dedicated foam bender
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I think weight (or gyro stabilization) can help in gusty conditions. Smooth wind shouldn't be a factor until it gets up closer to your cruising speed, say around 2/3's or so.

Ballasting is really only applicable for sailplane type flying where power is wind driven.

I think the primary factor that has been missed is gusts and not so much wind-speed
 

xuzme720

Dedicated foam bender
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Yessir! I guess rather than gust I should have used turbulence...Heavier only works better in dealing with turbulence.

That looks better! and it's short!
 

RoyBro

Senior Member
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OK, this is a very interesting subject, and I've read through all the posts (for the most part). I love physics, and I love teaching. So I can't help but give it a go here.

First we need to take the subjectivity out of the question. That is, the word "better". Now let's examine two hypothetical air frames. They are both made out of the same material and are identical in every way, except that air frame B is half again the weight of air frame A. So, if air frame A is 20 grams, air frame B is 30 grams. Now for the motors. They are weightless and the variable property is power. Now you see why these planes have to be hypothetical. ;)

So with zero wind, will plane B require more or less power to take off than plane A? What about to stay aloft once airborne?
I think we can agree that plane B will require more power to fly than plane A. Also once in the air, it will not be able to perform exactly like plane A because of momentum. Momentum is Mass x velocity. So if we provided plane B with just enough power to match plan A's speed, plane B would always have more momentum.

Scenario 1: Both planes are flying in a parallel formation and come in for a landing. All other variables are the same, touch down, throttle cut, etc. The only forces acting on the planes at landing are gravity and friction, which are equal and constant for both. Which plane will come to a stop first? Which plane will roll farther? Plane A will stop first and plane B will roll farther because it takes more force to influence an object that has more momentum. That's basic physics.

Scenario 2: Again,both planes are flying in a parallel formation, and both are suddenly hit by a 5 MPH gust of wind exactly perpendicular to their flight path. Because it takes more force to influence an object with more momentum, which plane will be more influenced by the sudden gust of wind? Of course plane A will be influenced more by the gust of wind because it has less momentum than plane B. That's physics.

Plane A and plane B will perform differently given the same set of circumstances. Now keep in mind that these are hypothetical planes. In the real world a plane made from heavier material would probably have a different airfoil as well as a more powerful motor, which probably adds more weight. And because it requires more force to influence how it flies, it will probably have larger control surfaces, etc., ad infinitum.

The whole question about one plane being better or worse, is based on the pilot's expectation of the performance. Some, like earthsciteach will prefer a lighter plane with enough power. I don't think I could handle that same plane in windy conditions as well as earthsciteach could, so I would prefer a plane that is less susceptible to the effects of the wind. The plane that would be "better" for me to fly may be a heavier plane, not because it performs better, but because of my skill level.

So how's that for a very verbose, politically correct, diplomatic non-answer? :D

RB
 
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OutcastZeroOne

Fly, yes... Land, no
I had a feeling I would set off a bit of a powder keg. Not as bad as Mac vs Micro$oft or PS vs X-box, but right below it.

The reason I was saying to make 2 planes and fly them together was to make sure they both where in the same conditions. Where I live conditions can change quickly. It can be calm for hours then a massive bit of wind, lower winds, and nothing again. Being on the coast dose that.

I get the more mass means more dampening. Still would be interesting to see it done though.
 

pgerts

Old age member
Mentor
.... So how's that for a very verbose, politically correct, diplomatic non-answer? :D RB
Why not try to make 2 planes like an old F3A model with a Power source of approx 1 kW (1,5 hp), one with a weight of 2,5 kg (5 lbs) - the light version and the other with a weight of 3,5 kg (7 lbs).
Both are realistic weights of the same plane and the top speed is about the same as the wind resistance is the big issue, not the weight of the plane.

That is a lot more realistic than calculating on your ultra Micro planes with a weight of 20 or 30 grams not suitable for winds.
Go up to something fully glased close to 50 grams and a speed near 70 mph like this and you wont feel a gust of 5 mph.
100720-08.JPG
 
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Craftydan

Hostage Taker of Quads
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The reason I was saying to make 2 planes and fly them together was to make sure they both where in the same conditions. Where I live conditions can change quickly. It can be calm for hours then a massive bit of wind, lower winds, and nothing again. Being on the coast dose that.

Naw, don't make 2 planes, build a bomb bay at CG, and "drop" some weight mid flight ;)
 

MrClean

Well-known member
Well basically we pointed that out with sailplanes and slope soarers and then was poo poo'hd for making a non ideal reference.

Personally, I like the way I said it best. But then I am the balm of humanity. The sticky white glue stick of mankind's craft paper. If I was in a small jar with a brush in it, people would eat me in 2nd grade.
 

RoyBro

Senior Member
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MrClean, you are absolutely right (about making the same points). But sometimes people just need a very generic context. Even in my example, as soon as we left "Hypothetical World", things started getting too complicated to track all the variables.

But I'm not sure about glue stick thingy. ;)
 

Craftydan

Hostage Taker of Quads
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But then I am the balm of humanity. The sticky white glue stick of mankind's craft paper. If I was in a small jar with a brush in it, people would eat me in 2nd grade.

But would you be foam safe? ;)
 

MrClean

Well-known member
Absolutely.

Reminds me of the new Willy Wonka movie.

"Everything in this room is edible. Even I am edible but that is called cannibalism and is in fact frowned upon in many places."