Plane on a conveyor belt

[Bengal]

I just talked to a pilot friend of mine as well, don't know why I didn't think of that earlier...

Lift is achieved when the air flow over the wings is greater than the weight of the plane, makes sense right?

What it comes down to in this expierement is how they pull it off. If they can keep the plane still, it won't create lift, it won't fly. Everyone can agree on that...

But that is the stickler, CAN THEY KEEP THE PLANE STILL? That's what we are arguing. We should rephrase the question that way. If you think they can keep the plane still, it won't fly, no one will argue the oposite of that. If they can't, it will fly...

So that is the arguement. Can they keep the plane still. In theory they should be able to. But that's only in theory...

I go with what I posted above. I bet there is no difinitive answer in tonights program. Somthing will fail with the test. You'll hear one of them say, "If we had only tried this, this would have been the outcome". Or "If we had used this kind of conveyor belt and not a 3000 foot tarp, this would have happened causing this to happen". I fear we may never have a concrete answer...

[Cygnus X1]

then put your money where your mouth is! let's do an internet handshake for $20. loser paypals $20 to the winner.

I have too many vices. Gambling is one I avoid like the plague.

It mgiht just come down down to minutae, such as, "well, it lifted a
quarter of an inch, therefore it flew"...so, no. I admit, I'm chicken.

Won't fly.

[pjg]

You can drive a plane on the ground 300+ MPH and never leave the ground. If you never leave the ground, you never have a recordable Air speed. Air speed is the speed something travels through the air, with no part of the object touching the ground. A plane going 60 MPH on the ground has 0 air speed.

Chances are at 300 MPH you couldn't keep it ON the ground unless you are pushing the yoke so hard you are about to snap the nose wheel off (negating the usually built in positive wing angle of incidence). Of course there are variables, wing design, weight, etc. But your average plane will lift off with 300MPH of airspeed thanks to Mr Bernoulli. BTW, a low pressure above the wing created by the camber of the wing sucks the plane into the air, not a high pressure below the wing as a previous poster stated.

Airspeed is the speed of the air over the wing. It doesn't matter if you are on the ground or in the air. I have sat with the brakes on and the nose pointed into the wind and the plane has indicated an airspeed. There have been times when the wind was strong enough you could feel the plane getting light on the struts. Also, during the take-off roll V1 is called out as an airspeed, even though the plane is still on the ground.

Ground speed really means nothing to an airplane. Some planes can't measure it. Others, like the ones I work on, either compute it using an INS or GPS or an AHRS system. This is purely for estimating the time to destination.

For any of you sticklers out there, some planes can display groundspeed through the antiskid transducers, but I haven't seen a flight crew procedure yet that uses that info.

As far as this debate is concerned, if the question is: If you set a plane to take off power and the conveyor will match the airplane wheels spinning speed in the opposite direction, then yes I believe it will fly. And probably will take off in about the same distance.

If the question is: If you set a conveyor belt to an airplanes takeoff speed and set the plane on the conveyor belt with just enough thrust set to keep it in place, then no, it obviously won't fly.

It's all about the airspeed.

[StukaJU87]

ok. who is betting on this one. I want in. It will not fly.

I think it will. Chris just bet me the wheels off his Mustang against my can of sardines. I can't lose.:ROTF:

[SeventhSon]

ok. who is betting on this one. I want in. It will not fly.

ok, i'm in. the bet is for $20. the bet is whether both the toy plane and the real plane take off and fly.

i say, yes, both planes take off and fly.

loser pays winner $20 by paypal.

you in?

[RobRR]

I think we should get a neutral party, send all the money to them for safe keeping, then once we find out that the planewill or will not take off, the winnings go to them.

[Bengal]

I think we should get a neutral party, send all the money to them for safe keeping, then once we find out that the planewill or will not take off, the winnings go to them.

OK, you've got 8 hours...

I guess it's a push if the show proves nothing, right? If the test itself is flawed or the tarp doesn't work like a real belt would. We'll see...

[texasfury]

........

[guitarsjb]

I think we should get a neutral party, send all the money to them for safe keeping, then once we find out that the planewill or will not take off, the winnings go to them.

If I read this right..If I'm said neutral party, you guys send me your money, and when we find out the answer tonight, I get to keep the money?? I'm in :ROTF:

[texasfury]

........

[RobRR]

[Bengal]

This problem cannot be answered definitively until these two variables are set:

1) Will the belt stay at a constant speed, or will it speed up to match the jet's forward motion?

2) How long is the belt?

Until these two variables are set, all your arguing is about nothing.

I'm guessing you didn't watch the video in the first post...

[dg]

After watching the video again, I'm not betting, because it looks like their plan is to make sure the plane doesn't move forward, even if that means controlling the throttle of the plane to make sure it sits in place.

In the model plane test, the conveyor belt is not much longer than the plane, and it looks like they are just going to run it at a constant speed and try to keep the plane in place. Of course the plane won't take off if that's what they do. In the word problem, it is the responsibility of the conveyor belt to try to match the plane and keep it in place. If it can't, tough shit. That's the whole point. The plane's job is to try to take off, not stay in place on the belt. If they don't peg the throttle, they are not trying to take off, and their test is bogus.

In the second part, you hear the pilot say, "If I match my speed to the conveyor belt, and no air passes over the wings, I'll just sit there like a brick." Duh, everybody on both sides of the argument agrees on this point. The pilot's job is to try to take off, not match his speed to the conveyor. If the pilot tries to match the conveyor rather than trying to take off, then again I say their test is bogus.

Hopefully, I'm wrong and they are going to try to take off rather than match the planes to the conveyors, but watching that video makes it look like they are all about trying to keep those planes still.

[fuel0707]

As an aeronautical engineer and as a professional pilot, I'm looking forward to this episode of "Mythbusters". I've got the DVR all set to record it.

[Ralph E.]

dg, isn't that the whole point of the argument? That the conveyor belt goes the same speed (in reverse) as the airplane? That's how I took it, in which case the plane won't take off IMO.

Am I not understanding the myth here?