Poison filled Hollow Points?

[Circuits]

Yes, that is all true, except if the props are running for all it's worth, the plane WILL be moving forward, regardless of what the treadmill is doing, because the wheels are free spinning. Do you agree?

Flight has nothing to do with speed, but with airflow over the airfoil (wing, usually).

If a plane has a 90-knot stall speed, then facing it into a 90-knot wind will give it all the lift it needs to take off, even if it's sitting still at 0 groundspeed, with the engine off. Shortly after such a takeoff, though, drag would have the plane moving increasintly backwards, reducing its true airspeed, and depriving it of enough airflow to sustain flight.

The powerplant of an aircraft exists to counteract drag, and achieve/maintain an appropriate airspeed for lift and positive control.

Scale model tests of a treadmill scenario are grossly misrepresentative, because a model plane can easily have enough thrust to weight to fly without wings, and even without that much thrust, the propwash itself provides some airflow over the wings in a prop-forward engine configuration.

No matter how fast the treadmill is "going", if the airfoil is motionless, with no headwind, the only airflow over the wings is feed air for a pusher prop, or propwash for a tractor prop, and the plane ain't taking off unless that feed or wash air provides enough lift all by itself.

[rondog]

Flight has nothing to do with speed, but with airflow over the airfoil (wing, usually).

If a plane has a 90-knot stall speed, then facing it into a 90-knot wind will give it all the lift it needs to take off, even if it's sitting still at 0 groundspeed, with the engine off. Shortly after such a takeoff, though, drag would have the plane moving increasintly backwards, reducing its true airspeed, and depriving it of enough airflow to sustain flight.

The powerplant of an aircraft exists to counteract drag, and achieve/maintain an appropriate airspeed for lift and positive control.

Scale model tests of a treadmill scenario are grossly misrepresentative, because a model plane can easily have enough thrust to weight to fly without wings, and even without that much thrust, the propwash itself provides some airflow over the wings in a prop-forward engine configuration.

No matter how fast the treadmill is "going", if the airfoil is motionless, with no headwind, the only airflow over the wings is feed air for a pusher prop, or propwash for a tractor prop, and the plane ain't taking off unless that feed or wash air provides enough lift all by itself.

That's how I see it too.

Scale model tests of a treadmill scenario are grossly misrepresentative, because a model plane can easily have enough thrust to weight to fly without wings

LOL! Ever seen the videos of "flying lawnmowers"?

[rhineoshott]

Flight has nothing to do with speed, but with airflow over the airfoil (wing, usually).

If a plane has a 90-knot stall speed, then facing it into a 90-knot wind will give it all the lift it needs to take off, even if it's sitting still at 0 groundspeed, with the engine off. Shortly after such a takeoff, though, drag would have the plane moving increasintly backwards, reducing its true airspeed, and depriving it of enough airflow to sustain flight.

You can actually fly backwards (groundspeed) in a small plane if you have enough headwind.

[Irving]

Okay, let me try from a different angle.

The wheels on an airplane are free spinning. All they do is spin to reduce friction to allow the airplane to take off. The only time the wheels have any effect on the movement of the airplane is when the brakes are applied right?

When an airplane takes off, it achieves the proper speed by either being pushed by a jet, or pulled by a prop. The wheels in no way directly contribute to any forward motion of the airplane right?

If a free spinning wheel can not accelerate the plane, then they also can not decelerate the plane, so it won't matter how fast the treadmill is spinning; because all forward propulsion is provided by the props/jets, which are not effected by the treadmill at all.

It's really a trick question, because people picture how a standard passenger car would react with a treadmill, not an airplane.

To test this theory, one wouldn't even need to spend the money for a model airplane. They could just take a Co2 rocket car and launch it on a running tread mill. Just build a rig that would allow the car to be held at the bottom of the treadmill, and turn the tread mill on full speed. With the treadmill going full speed and the car not moving at all, you'd think that the treadmill would have an advantage, but it wouldn't. Once you punch that Co2 canister, that little balsawood car is going to fly right off the end of your treadmill and through your wall, because the force on the car is provided by the Co2 and not the wheels.

[Irving]

Someone please explain to me how the treadmill has an effect on the forward motion of the airplane when the wheels are free spinning.

[sniper7]

wow how did it get to this.

okay, just so you all know, I am an airline pilot. I do this stuff every week (not off a treadmill mind you).

You must forget about wheels as you think of them on a vehicle. A car transfers it power through its tires to the ground. an airplane transfers it power through a propeller to push air. The wheels are simply there to reduce friction, give a piece of material that is easily changed out and provide a small amount of impact absorption on the "bad landing days"

With that in mind, think about the axle, it is in the center of the wheel, the wheel rotates around that axle, and your friction from the ground is now not direct against the axle but the friction is rotated at an angle.

In the problem with the treadmill, friction is negligent. even if it was not negligent, the airplane would still fly. as long as the tires were rated to the correct speed. ours are good to 164 knots ground speed. (about 188 mph)

the engine, whether turbine or piston produces thrust or power. A jet engine will push an airplane using thrust. basically the engine sucks in air, compresses it, burns it with fuel and pushes it out the back at a high speed pushing the airplane forward. wheels have nothing to do with this other than to make it easier for the plane to move forward.

The final answer to the question is THE AIRPLANE WILL FLY. what will happen on the sidelines will be the tires will be moving at twice their normal speed (call it 150MPH normally), so they would be rotating at 300 MPH. in real life they would separate more than likely with catastrophic results.

Airplanes require speed over the wings in order to fly. lets call it 120 mph to lift off the ground. that either requires a very strong wind blowing over the wings while the plane is stationary, or it requires forward movement of the wing through the air. either way lift is created.

well, as mixed up as all the info is, hopefully you understand that the tires have very little to do with the airplane actually flying other than to reduce friction.

[Irving]

Oh, looks like Mythbusters actually did do this. The plane took off without a problem. I didn't know they did this already until I looked it up.

http://www.youtube.com/watch?v=YORCk...eature=related

The comments are funny because people still don't understand that there is no connection between the belt and the prop. I'll start another physics question in its own thread.

[sniper7]

Not if the treadmill is running at the same speed. That's how I understand the myth, the treadmill is going the same speed as the forward motion of the plane, so the plane is essentially standing still, even though it's at takeoff power and the wheels are spinning.

In other words, if you were standing next to the plane while this was going on, and the plane isn't moving forward in relation to your position, it's not going to lift off.

not true

[sniper7]

Flight has nothing to do with speed, but with airflow over the airfoil (wing, usually).

If a plane has a 90-knot stall speed, then facing it into a 90-knot wind will give it all the lift it needs to take off, even if it's sitting still at 0 groundspeed, with the engine off. Shortly after such a takeoff, though, drag would have the plane moving increasintly backwards, reducing its true airspeed, and depriving it of enough airflow to sustain flight.

The powerplant of an aircraft exists to counteract drag, and achieve/maintain an appropriate airspeed for lift and positive control.

Scale model tests of a treadmill scenario are grossly misrepresentative, because a model plane can easily have enough thrust to weight to fly without wings, and even without that much thrust, the propwash itself provides some airflow over the wings in a prop-forward engine configuration.

No matter how fast the treadmill is "going", if the airfoil is motionless, with no headwind, the only airflow over the wings is feed air for a pusher prop, or propwash for a tractor prop, and the plane ain't taking off unless that feed or wash air provides enough lift all by itself.

mostly correct, but the force of the treadmill on the tires is pretty much negligible compared to the thrust of an engine pushing air. no matter what the wheels are doing the airplane can roll because there are no gears. free spinning tires (with brake assemblies) rotating around an axle. the plane will fly.

[Irving]

High five Sniper.