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Re: Planes take off , off trailer [Re: hooziewhatsit] #2795118
07/10/20 12:19 PM
07/10/20 12:19 PM
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Crook County, ILL
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In this case the plane isn't much different than a glider. A glider gets towed either by a powered aircraft or a winch/catapult type mechanism on the ground, and when the airflow over the wings is fast enough to create adequate lift, the glider flies. Or maybe better to compare to a plane getting catapulted off an aircraft carrier, where the catapult accelerates the plane to a speed where the wings develops lift, and then the thrust of the engines takes over to keep the plane flying at a speed required to maintain the lift.
If you put an airplane with the engine not running on a platform and accelerated the platform fast enough, the plane would start to fly after developing lift, and the plane would glide back down to the ground, or stall and crash into the ground depending on circumstances and how fast the pilot could react on the controls etc.
I thought the old plane on a treadmill theory had got beaten to death years ago, even Mythbusters did an episode on that. catfight

Re: Planes take off , off trailer [Re: bigdad] #2795151
07/10/20 01:39 PM
07/10/20 01:39 PM
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Rio Linda, CA
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Taking off from a moving vehicle is fairly easy, some STOL aircraft can get airborne in a stiff wind..... landing OTOH...............

https://www.youtube.com/watch?v=a8Fx_ir6McI


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Re: Planes take off , off trailer [Re: John_Kunkel] #2795201
07/10/20 03:44 PM
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Re: Planes take off , off trailer [Re: Andrewh] #2795253
07/10/20 06:46 PM
07/10/20 06:46 PM
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Sorry, but no Hoosie. The treadmill is causing you to go backwards. Therefore, you have airflow coming from behind you if you are losing ground. You are moving forward against the belt, yes, but not the relative wind. You will not takeoff, you will not fly, and you will not collect 200 bux (you will not pass go!) LOL

The only way you can takeoff on a treadmill is if you have a very loooooooooooooooooong treadmill and you are actually moving forward on it. AND the problem with this is that the engine will have to spin even faster to offset the original speed of the treadmill. Now if the treadmill is running in reverse, you will need less power, just like the truck pulling that float plane!

Re: Planes take off , off trailer [Re: roadrunninMark] #2795256
07/10/20 07:06 PM
07/10/20 07:06 PM
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St. Charles, MO
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Wow. I can't believe we are having this conversation again! grin

I think some car guys have trouble grasping the concept because they are so used to thinking about wheels pushing against the pavement.

In a plane the engine is pushing against the air, not the ground. So a conveyor belt has no effect other than to make the landing gear wheels spin a little faster. No effect.


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Re: Planes take off , off trailer [Re: roadrunninMark] #2795257
07/10/20 07:11 PM
07/10/20 07:11 PM
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Oregon
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Nope.

Stand on the ground, holding a wheelbarrow, and put the front wheel on a treadmill. Speed up the treadmill, and observe how the wheel spins at the same speed as the treadmill, but the wheelbarrow stays in one place.

Then see that if you push the wheelbarrow forward (on the moving treadmill), it moves forward regardless of how fast the treadmill is going. Heck, make the treadmill go in reverse, and observe how you can still push the wheelbarrow forward and back.

The original question is flawed in assuming the treadmill can hold the plane back. It can't.

HOWEVER, if the wheels of the plane were driven by the engine to be the same speed as the treadmill, then yes, it would never have any forward motion or airspeed, and never take off. But I've never seen a plane with powered wheels.


If you ever find yourself in a fair fight, your tactics suck.
Re: Planes take off , off trailer [Re: wingman] #2795259
07/10/20 07:12 PM
07/10/20 07:12 PM
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Oregon
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Originally Posted by wingman
Wow. I can't believe we are having this conversation again! grin

I think some car guys have trouble grasping the concept because they are so used to thinking about wheels pushing against the pavement.

In a plane the engine is pushing against the air, not the ground. So a conveyor belt has no effect other than to make the landing gear wheels spin a little faster. No effect.


up


If you ever find yourself in a fair fight, your tactics suck.
Re: Planes take off , off trailer [Re: hooziewhatsit] #2795283
07/10/20 08:23 PM
07/10/20 08:23 PM
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Here is a nice stol competition, who needs a treadmill, or heck even a runway for that matter?! https://www.youtube.com/watch?v=hPakbghLe38

Re: Planes take off , off trailer [Re: hudsonhornet7x] #2795296
07/10/20 09:09 PM
07/10/20 09:09 PM
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Tucson, AZ
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This thread was fun the first time... grin

Re: Planes take off , off trailer [Re: Ramrod39] #2795299
07/10/20 09:20 PM
07/10/20 09:20 PM
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Hoosie, your example is flawed. If someone stands on the ground holding the handles of the wheelbarrow, of course the wheel will speed up or slow down with the speed of the treadmill, but it is only the wheel. The person is acting as an anchor. Again, the body of the wheelbarrow is not moving forward or reverse. Also, how does this even relate to an airplane if it was on the treadmill? Is there a wheel (tail or nose wheel, doesn't matter which) that will not be on the treadmill? If this is the case, again, the wheels will spin but the airplane will have no forward momentum, as the person. Therefore, no airflow over the wings of the relative wind (only the wind blown by the propeller, which is no where near enough airflow).

Re: Planes take off , off trailer [Re: roadrunninMark] #2795329
07/10/20 11:17 PM
07/10/20 11:17 PM
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actually your example is flawed.
the airplane does not depend on the wheel speed for its speed.
the issue is the drag on the wheels is not enough to slow the plane down against the engine.

IF the plane wheels brakes were on, then it would slow the plane down against the engine.
but freewheeling doesn't prevent the plane from moving faster than the treadmill can pull it backwards by the wheels.

Re: Planes take off , off trailer [Re: Andrewh] #2795339
07/11/20 12:54 AM
07/11/20 12:54 AM
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Oregon
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Andrew is correct.

Instead of hanging on to the wheelbarrow, put an engine with a propeller in it. And assume it balances on one wheel. It's an analogy, deal with it laugh2

The propeller will provide the forward motion, just like when you push it by hand.


If you ever find yourself in a fair fight, your tactics suck.
Re: Planes take off , off trailer [Re: hooziewhatsit] #2795437
07/11/20 12:14 PM
07/11/20 12:14 PM
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I know the aircraft doesn't depend on wheel speed to be able to takeoff,and I said that earlier, it depends upon the relative wind moving, mainly under the wing surface. I was referencing Hoosie's statement of one holding the end of the wheelbarrow with the treadmill rotating the wheel.

Now in his new example, he is putting a propeller and engine on the wheelbarrow. On one wheel, 3 wheels, doesn't matter how many wheels, the propeller now pulling wheelbarrow/airplane forward, yes the engine, if strong enough, can counteract the treadmill as it attempts to move the wheelbarrow/airplane backwards. If WB/AP is in a static position, (treadmill moving it back at same speed engine pulling it forward) it will NOT take off. IF the engine is pulling it forward, at a speed it would normally lift off at (in this case: Takeoff speed = normal rotation speed (at a given weight) + speed to overcome the treadmill's belt speed, then yes it is possible.

So if you have a treadmill that is EXTREMELY long, and the aircraft is actually making forward progress and is able to overcome the treadmill speed AND reach normal takeoff speed, then yes it is possible. If it cannot read that speed, then no, it isn't going to takeoff.

Re: Planes take off , off trailer [Re: roadrunninMark] #2795448
07/11/20 12:52 PM
07/11/20 12:52 PM
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Tulsa OK
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So those of you who think a plan can't take off on a treadmill.......can a plane fly over a treadmill or will it fall from the sky? Could we pull aircraft from the sky with giant treadmills on the ground?

Planes aren't wheel driven, that is why they can take off on treadmills, a plane on a treadmill will still go forward with the thrust from the propeller, the wheels might be turning at a higher rate of speed than normal but it will take off just fine.


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Re: Planes take off , off trailer [Re: Bad340fish] #2795694
07/12/20 07:06 AM
07/12/20 07:06 AM
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I am surprised no one has brought up catapults on aircraft carriers.

New electro catapult problems on USS Gerald Ford.

Truck and trailer mounted catapults for Drones.

Rocket assisted bomber take offs.

Re: Planes take off , off trailer [Re: 360view] #2795818
07/12/20 01:47 PM
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My point with the wheelbarrow is to try and show how what the treadmill does has no effect on whether the plane can move forward or not, when acted on by the propeller.

Yea, a plane on a treadmill without the engine running will move backwards, but only until the engine starts. Then it will move forward like it was on solid ground.


If you ever find yourself in a fair fight, your tactics suck.
Re: Planes take off , off trailer [Re: 360view] #2795903
07/12/20 05:56 PM
07/12/20 05:56 PM
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N.E. OHIO, USA
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Originally Posted by 360view
I am surprised no one has brought up catapults on aircraft carriers.

New electro catapult problems on USS Gerald Ford.

Truck and trailer mounted catapults for Drones.

Rocket assisted bomber take offs.


You know that if the aircraft carrier could go fast enough to create enough wind speed to create lift on a plane sitting on a treadmill on the deck it would lift it and if you started the engine it could fly away. Brings up the fact that a vertical take-off Harrier jet could easily take off on a moving treadmill as could any plane with more forward thrust than a moving tread mill. FORWARD or upward THRUST and wind speed greater than wheel spin it will fly. Carry on catfight laugh2

Re: Planes take off , off trailer [Re: bigdad] #2797667
07/16/20 10:50 PM
07/16/20 10:50 PM
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catfight

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