How about a float plane? No wheels, just pontoons.
Can it get airborne on a river by taking off while headed upstream, or does it have to go downstream only in order to take off?
Originally posted by mwmiller How about a float plane? No wheels, just pontoons.
Can it get airborne on a river by taking off while headed upstream, or does it have to go downstream only in order to take off?
And how about a float plane on a LAKE? No water running up or downstream, just a bunch (or bushels) a water sittin' there doing nuthin.
Originally posted by lemon lime And how about a float plane on a LAKE? No water running up or downstream, just a bunch (or bushels) a water sittin' there doing nuthin.
So there you have it.
The conveyor belt doesn't really have an effect and is irrelevant.
The surface of the water for a sea or float plane is also irrelevant.
The plane will become airborne in any case when the wings are moved through the air fast enough to create the necessary amount of lift.
Also think of a glider. It is towed until there is enough lift on its wings to get it into the air.
Originally posted by mwmiller So there you have it.
The conveyor belt doesn't really have an effect and is irrelevant.
The surface of the water for a sea or float plane is also irrelevant.
The plane will become airborne in any case when the wings are moved through the air fast enough to create the necessary amount of lift.
Also think of a glider. It is towed until there is enough lift on its wings to get it into the air.
Right, air flow over/under the wing creates lift. The shape of a planes wing causes air to move faster across the top of the wing, so there is less air pressure above the wing than below. So you can look at this in one of two ways... the wing is being pulled up from above, or being pushed up from below.
But the air (wind) has to be moving across the wing for this to happen. If a conveyor belt is preventing forward motion of the plane then what is causing 'calm' air to move across the wing? Obviously the propeller (or jet) is causing air to move and flow past the wing, so even if the plane remains stationary lift can be accomplished.
Originally posted by mwmiller So there you have it.
The conveyor belt doesn't really have an effect and is irrelevant.
The surface of the water for a sea or float plane is also irrelevant.
The plane will become airborne in any case when the wings are moved through the air fast enough to create the necessary amount of lift.
Also think of a glider. It is towed until there is enough lift on its wings to get it into the air.j
... when the wings are moved through the air...
Yes, but if the wings are stationary (conveyor belt prevents forward motion) the wings are not moving through the air... the air is moving, not the wings.
Originally posted by Shallow Blue Yes - and the Mythbusters proved not only that it should, but that it does.
The reason, by the way, is that a plane taking off is not driven by its wheels - those are in free spin. No matter how fast the conveyor belt goes, all that happens is that the wheels spin faster and the rest of the plane barely feels the effect. The effect of the propellor or jet exhaust, meanwhile, does propel the plane forward until it takes off.
The effect of the propellor or jet exhaust, meanwhile, does propel the plane forward until it takes off.
'Forward' in relation to what? If the plane remains in a fixed position in relation to the ground then the plane can only be moving forward in relation to the already moving air. There is actually no myth being busted here because the myth itself is flawed, as well as the explanation busting the 'myth'... the explanation contradicts itself by assuming forward motion from a fixed position that does not change. A fixed position does not move around while remaining in a fixed position... and by 'fixed position' I mean it can't move forward or backward, it can only move up or down.
The conveyor belt is not preventing the plane from doing anything.
The plane will be moved forward by the engine whether it is on a conveyor belt or on solid ground.
If the plane moves forward at 5 mph, the belt moves in the opposite direction at 5mph, as described in the OP.
The wheels would then roll at 10 mph, but the plane would still move forward at 5 mph.
The propeller wash does not create lift on the wing surface. The plane being moved through the air does that.
The plane is moving through the air but is not being driven by the free-wheeling wheels.
The wheels provide only a low-friction contact point to the surface on which the plane sits or rolls.
Originally posted by mwmiller The conveyor belt is not preventing the plane from doing anything.
The plane will be moved forward by the engine whether it is on a conveyor belt or on solid ground.
If the plane moves forward at 5 mph, the belt moves in the opposite direction at 5mph, as described in the OP.
The wheels would then roll at 10 mph, but the plane would still move forward a ...[text shortened]... heels provide only a low-friction contact point to the surface on which the plane sits or rolls.
If the conveyor belt isn't preventing the plane from doing anything then what is it doing, and what is the point (what is being proven) having the plane on a conveyor if has no effect on what the plane is doing? The wheels are free spinning and can't keep the plane anchored in one place, so of course the plane can move forward. And you don't need to tell me the wheels aren't motorised, I understand the purpose of having wheels on a plane when it's on the ground. Good grief, I hope no one tries explaining why wheels aren't needed when the plane is in the air... because everyone knows the plane can't remain airborne without its wheels.
Originally posted by mwmiller The conveyor belt is not preventing the plane from doing anything.
The plane will be moved forward by the engine whether it is on a conveyor belt or on solid ground.
If the plane moves forward at 5 mph, the belt moves in the opposite direction at 5mph, as described in the OP.
The wheels would then roll at 10 mph, but the plane would still move forward a ...[text shortened]... heels provide only a low-friction contact point to the surface on which the plane sits or rolls.
Okay, I get it now. I thought the claim was that the plane could experience lift even if it stayed in the same place... but that wasn't the point or reason for the experiment.
This one has been around for quite a while and was posted here several years ago. It generated a lively and interesting discussion that stayed hot and active for a long time. I don't remember now who originally posted it but I thought it would be interesting to see how it held up after all this time.
One of the participants was a pilot and maybe he was the one who posted the original question back then. Apparently the question was presented to a group of pilots and it even created some heated arguments within that group. (OK, I went back and looked it up. It was started in 2004 by flyunity, who is a pilot. Here's the link.)
Originally posted by mwmiller This one has been around for quite a while and was posted here several years ago. It generated a lively and interesting discussion that stayed hot and active for a long time. I don't remember now who originally posted it but I thought it would be interesting to see how it held up after all this time.
One of the participants was a pilot and maybe he was ...[text shortened]... puzzles/will-the-airplane-fly.54537
In addition there were also other threads on the topic.
Because we were talking about an airplane and not for example a jet powered wagon (with free spinning wheels) I allowed myself to think the problem had something to do with it being an airplane. Wings and lift had nothing to do with it.
There's a game we've been playing at the club I belong to with questions designed to fool us into giving wrong answers... this airplane scenario reminds me of that game. I'm not a pilot, but I am somewhat surprised a pilot would have any trouble with this.
Airplane on conveyor belt runway question.
26 Nov '15 00:33
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