will it take off?

[RonMar]

Re: Mythbusters/airplane/treadmill

But, that is not possible, right?
Is this another one of those "moot point doesn't matter" discussions?

If not impossible, certainly very impractical. It just dosn't take that much energy to spin up the wheels. Minor fractions of the prop thrust moving the plane forward, and the belt going to the rear. And if you are talking about super accelerations of the conveyor belt, Any rapid acceleration of the plane to the rear caused by inertial drag of accelerating the tires, would also be resisted by the planes greater mass. Kind of like the person ripping the tablecloth out from under the dishes on the table. A quick acceleration overcomes the friction and the mass of the dishes keeps them relatively stable and pretty much in the same position. The same thing can be done with a toy car or plane setting on the table. The tablecloth can be jerked right out from under them.

Do the wheels take energy to accelerate? YES. Did it impede the aircrafts ability to take off? I am sure it did to some degree, but it was by such a small margine as to be extremely difficult, if not impossible to measure accurately... The belt went backward, the plane accelerated forward and took off in what appeared to be normal distance... Myth Busted.

 

[SPYDERLK]

Re: Mythbusters/airplane/treadmill

But, that is not possible, right?
Is this another one of those "moot point doesn't matter" discussions?

It matters because it is theoretically possible and thereby worth an understanding of the physics making it so. The theory has the math to determine whether it could be done within material strength of presently available materials. My guess is that any wheeled plane that has a thrust to weight ratio below 1/2 could be held completely still or even pulled backward under full thrust for a second or so before something in the wheel or the conveyor system failed. The engineering involved in such a demonstration would be prodigious. What a big deal to show doubters the validity of what physics and math describe. And no, the plane probably wouldnt be able to take off due to the damages inherent in the mechanical failure.
larry

 

[MossRoad]

Re: Mythbusters/airplane/treadmill

Thread closed. Please continue this discussion in the original thread, as this one has the potential to become a huge monster post as well. We will try to merge this post into the other one. Wish us luck.

Here's the link to the original thread.

Click here please.

 

[MossRoad]

Looks like it worked. The two threads should now be merged. Please continue this most fascinatiing discussion.

 

[RobJ]

Maybe its just me but sometimes its hard to tell what side people ore on.

BTW, the helo will take off to...same reason the plane takes off. :d

 

[RobS]

Maybe its just me but sometimes its hard to tell what side people ore on.

BTW, the helo will take off to...same reason the plane takes off. :d

I'm going to disagree on the helo. Assuming the turntable rotates at the same speed as the rotor shaft, the helo body will be spinning but the rotor will be stationary. Stationary rotor = no lift.

 

[RobJ]

I'm going to disagree on the helo. Assuming the turntable rotates at the same speed as the rotor shaft, the helo body will be spinning but the rotor will be stationary. Stationary rotor = no lift.

But the rotor will be spinning, turntable spinning at the same speed as the rotor shaft equals spining rotors connected to rotor shaft, like the prop on the plane. The question is if the turntable is spinning at the same speed as the rotor, will it take off. Answer yes, if the turntable is spinning at a speed where the rotor will produce lift to overcome the weight of the helo, yes it will lift.

Like the plane, the key here is the rotor IS spinning and producing a low pressure on top and high pressue air below...equal lift.

So RobS, will the plane fly on the conveyer?

When a helo loses a tail rotor, it still flys while it's spinning, just hard to control and somebody is gonna get motion sickness!!

Do we need a new thread on this one Moss? hehe

 

[RobS]

But the rotor will be spinning, turntable spinning at the same speed as the rotor shaft equals spining rotors connected to rotor shaft, like the prop on the plane. The question is if the turntable is spinning at the same speed as the rotor, will it take off. Answer yes, if the turntable is spinning at a speed where the rotor will produce lift to overcome the weight of the helo, yes it will lift.

Like the plane, the key here is the rotor IS spinning and producing a low pressure on top and high pressue air below...equal lift.

So RobS, will the plane fly on the conveyer?

When a helo loses a tail rotor, it still flys while it's spinning, just hard to control and somebody is gonna get motion sickness!!

Do we need a new thread on this one Moss? hehe

I'll wait for the new thread to continue the helo discussion...

See the early pages of this thread for my opinion on the airplane. I think I weighed in about mid-stream as well though my opinion did not change.

 

[RobJ]

I think I weighed in about mid-stream as well though my opinion did not change.

OK you could have just said Yes, it'll fly. But why would the helo be different. What about the airboat? there's another one to ponder.

I was a convert on the plane...from no to yes after some thought.

Ever seen one of these fly?

 

[ray66v]

If your lucky enough to have good froward speed when you loose a tail rotor in your heli you can keep it from spinning.