Plane on a Conveyor Belt

[chumdawg]

Actually the wheels don't have anything to do with it. Planes don't get their thrust or forward movement from their wheels as it comes from the prop/jet engine. That is the whole point.

Of course it has to do with the wheels, because the wheels give the plane something to push off against. If not for the wheels pushing off against the runway, then all the plane has to push off against is air--which is exactly how rockets work. Commercial aircraft are not designed to push off against just air for takeoff.

[TourSpoon]

Of course it has to do with the wheels, because the wheels give the plane something to push off against. If not for the wheels pushing off against the runway, then all the plane has to push off against is air--which is exactly how rockets work. Commercial aircraft are not designed to push off against just air for takeoff.

The wheels support the weight of the plane as the thrust of the engines (very similar to rocket engines) push against the air propelling the plane forward. The air flows over the wings creating lift which allows the craft to take off. The wheels have a supporting role only.

[chumdawg]

The wheels support the weight of the plane as the thrust of the engines (very similar to rocket engines) push against the air propelling the plane forward. The air flows over the wings creating lift which allows the craft to take off. The wheels have a supporting role only.

If we suspended you in mid-air, you could run your legs back and forth all day long but you wouldn't go anywhere. The wheels--and your feet, in this example--play a very important role.

You ever see a car spin its wheels on ice? That engine can rev as high as you like, and as long as those wheels don't get traction the car isn't going anywhere.

[iacas]

Of course it has to do with the wheels, because the wheels give the plane something to push off against. If not for the wheels pushing off against the runway, then all the plane has to push off against is air--which is exactly how rockets work. Commercial aircraft are not designed to push off against just air for takeoff.

Actually, that's exactly how they work. The propellers (or jet engine) pushes or pulls the plane through the air.

Airspeed is all that matters in a plane taking off or not. That's why it's easier to take off into the wind - you need less runway because your airspeed is higher. Since you start off with an airspeed of, say, 20 MPH instead of 0... you take off sooner. [QUOTE=chumdawg;116937]If we suspended you in mid-air, you could run your legs back and forth all day long but you wouldn't go anywhere. The wheels--and your feet, in this example--play a very important role.[/quote\ No, they don't. Except to support the plane and allow fairly frictionless resistance (so the plane doesn't scratch up the tarmac is it rolls around...).

You ever see a car spin its wheels on ice? That engine can rev as high as you like, and as long as those wheels don't get traction the car isn't going anywhere.

Cars don't have propellers or jet engines attached to them, do they?

BTW, a plane will take off on a purely frictionless surface, too. Even with the wheels "braked" and not spinning. You're wrong.

[chumdawg]

You are being intellectually dishonest to ignore the role that traction against the runway plays in building airspeed for the plane. You cite the 20mph headwind as aiding the plane in taking off, yet you seem to believe that the plane going 20mph forward does not offer an equal advantage. It seems you would like to have your cake and eat it too.

Question for you... If the conveyor belt were moving backward at 700mph, and the plane's max airspeed were 700mph, could the plane take off?

[iacas]

You are being intellectually dishonest to ignore the role that traction against the runway plays in building airspeed for the plane.

No I'm not. That's the purpose of wheels - to reduce friction to almost negligible limits. Once static friction is overcome, rolling friction is basically non-existent.

You cite the 20mph headwind as aiding the plane in taking off, yet you seem to believe that the plane going 20mph forward does not offer an equal advantage. It seems you would like to have your cake and eat it too.

It seems as though you do not understand physics.

Question for you... If the conveyor belt were moving backward at 700mph, and the plane's max airspeed were 700mph, could the plane take off?

Assuming the plane's tires, bearings, etc. could withstand spinning that fast (they don't overheat or blow out), yep, the plane would take off. To an observer standing a few hundred feet away on the ground, takeoff would look pretty normal.

The plane's max airspeed doesn't really matter. "Matching the speed" is a red herring. If the plane needs to 100 MPH to take off and the conveyor belt moves 1500 MPH backwards, the plane will still take off (above caveats about the bearings, tires, etc. included again). It would also appear to be a normal takeoff.

[JaY_B]

Is this not widely accepted by now the plane does take off. Accept it, plane + conveyor belt = lift off

[DirtCheap]

The plane takes off.

If you can't accept the reasons why, just pretend that its a miracle of science.

[Wisco-Kid]

Yes the plane takes off

[srjorion]

If we suspended you in mid-air, you could run your legs back and forth all day long but you wouldn't go anywhere.

If we suspended you in mid-air, and strapped a jet engine on your back, do you think you would move? Oh yeah, you would, and it would be the ride of your life!

The wheels--and your feet, in this example--play a very important role.

Car engines provide the power to turn the wheels which move the car. Airplane wheels are like wheels on a toy car: they spin freely. The jet engines "push" the airplane. The wheels just let the plane roll along the ground while taxiing, taking off, and landing. The only friction they provide is when breaking to stop while taxiing and during landing.

Guys, I'm a pilot with thousands of hours flying military and commercial airplanes. I also have a degree in engineering. Trust me when I say that the plan WILL fly. My reasons and counters to the "No" arguments are littered throughout this post.

[chumdawg]

Guys, I'm a pilot with thousands of hours flying military and commercial airplanes. I also have a degree in engineering. Trust me when I say that the plan WILL fly. My reasons and counters to the "No" arguments are littered throughout this post.

Would your plane take off if instead of wheels it had pegs supporting it off the ground? C'mon, you're a pilot. Would you approve of that setup?

[TourSpoon]

Would your plane take off if instead of wheels it had pegs supporting it off the ground? C'mon, you're a pilot. Would you approve of that setup?

Strap some skis on the plane, ice down the runway (so the skis don't disintegrate on the tarmac), throw a couple of snakes on board with Samuel L. and the sucker still takes off.

[iacas]

Would your plane take off if instead of wheels it had pegs supporting it off the ground? C'mon, you're a pilot. Would you approve of that setup?

Uhm, pegs aren't as frictionless as wheels. Here's another equally pointless variation: "what if you welded the plane to the runway?"

You're wrong. If you can't accept it, at least have the intelligence to give up.

[DirtCheap]

Okay...

Tie a roller skate to a string..

Put the skate on a treadmill and start it so that your holding the string is the only thing keeping the skate on the treadmill..

With me so far??

Now turn the treadmill up as FAST as it will go and see if you can still pull the skate off the treadmill by pulling on the string.

Same idea...
The plane gets its thrust from its propeller (in this case the string) and not its wheels. The propeller overcomes the treadmill (with the greatest of ease) because the plane does not depend on its wheels for thrust.

[JeffG]

Haha wow, I haven't been on this forum since last season and I come back to find a topic on one of my loves of life, flight!

I've been on several forums with this question asked, there have been hundreds pages on this very particular topic. There have been engineers, master's of physics, etc. all proclaim "of course not, it won't take off" verbally bashing all the lesser intellectuals around them, only to a few pages later go "oops...I get it now...it will fly."

So, if you are still in the "no it will not fly" crowd, make your points and questions as nice and non-arrogant as possible b/c a little while later it will "click" and you'll come drudging back to say, "Whoops, yeah I get it now."

To whoever, brought up about the car on ice to refute, you actually brought up a great example to oppose your own view of it. A car on a lake of ice, spins its wheels...goes nowhere right. Because the wheels are forced forward by the engine and just spin..no forward motion. Strap a propellor or a jet rocket (same principle...force by air) onto the hood of that car...and magically it moves forward. Why, b/c the force is applied to the AIR and not the ground.

Another example, say you are flying along and do a low pass over a runway. You extend your gear and touch down but don't let off the throttle. Do you all of the sudden slow to a stop b/c the "runway" is stationary? Nope, your wheels keep on spinning freely. Now start that runway on a big conveyer belt going backwards...slam to a stop? No, going the same airspeed, your wheels are just spinning backwards very quickly. K, that example might not work for the non-pilots.

The post below me has a good example, the force is exerted from another place besides the contact between the wheels and the ground its on.

its okay, we won't laugh if you say you are wrong...well..maybe a little.

[DirtCheap]

its okay, we won't laugh if you say you are wrong...well..maybe a little.

I heard this question about a year ago and my first reaction was "no way."

It's a common reaction. You're right.. Everyone eventually comes around.

[immts007]

aaa hahahahahhaha

LOL

This thread is goodtimes. Please don't ever shut it down

[srjorion]

Would your plane take off if instead of wheels it had pegs supporting it off the ground? C'mon, you're a pilot. Would you approve of that setup?

Nope, it would not take off and I wouldn't approve of that setup. However, that has nothing to do with this question. The plane is on a conveyer belt, not stuck in the ground with pegs. Two totally different situations.

....throw a couple of snakes on board with Samuel L. and the sucker still takes off.

Not with me at the controls! I'd be off that plane in a hurry!