will it take off?

[SPYDERLK]

Larry,

I do understand everything that you wrote and with the Mossroad link. My premis to overcome the "Magic" is to minimize and trivialize its only strength - instant and endless acceleration. The only way that it can transfer energy to the airplane is through friction (the contact between tires and belt). The reason that the links theory fails is TIME. The reason I chose the plane that I did was to emphasize the fact that it would take very little time to create lift and therefore reduce friction and belt induced drag. I chose a design that can accelerate regardless of the state of the wheels. Rotating, stopped (brakes on), or even rotating in reverse has no bearing on the outcome.

I agree that given enough time that the MCB would prevent the airplane from taking off. Given enough friction or as you say "traction" then the MCB wins. My idea is to reduce friction or traction and to overpower any negative effects of that friction. My airplane has Teflon wheels. It can out accerate its own wheels. It will accelerate fast enough, and lift will occur fast enough that its own wheels will not be able no maintain the friction to spin up without slipping. Add additional rearward acceleration (MCB) and the wheels just slip faster. Then its just a force drag equation. The plane will fly. If you're still not convinced... I just picked up a few gallons of synthetic oil for my truck and tractor. I could use a little tubing and route a continuous drip on my Teflon wheels. Yee Haw! Come on Mr. ME -three tractor man... Git 'er done.

Oh, and happy Thanksgiving.

Ok - acceleration wont be instant because nothing is, including airplane thrust. Regardless of how quickly it starts it doesnt hit - it shoves. Even an impact is not truly instant. You are right about this idea failing with time in real life. The question is how much time. Im quite positive that even a super plane can be held still for an infinite number of instants -- even longer if there is weight on the wheels during takeoff. Teflon is quite dense. Just machine gearteeth onto the periphery and mate it with a cogged conveyor. Im guessing it would remain still thru several half lifes of ozone. And thats a long time in ozone years.
Larry

 

[NorthwestBlue]

Ok - acceleration wont be instant because nothing is, including airplane thrust. Regardless of how quickly it starts it doesnt hit - it shoves. Even an impact is not truly instant. You are right about this idea failing with time in real life. The question is how much time. Im quite positive that even a super plane can be held still for an infinite number of instants -- even longer if there is weight on the wheels during takeoff. Teflon is quite dense. Just machine gearteeth onto the periphery and mate it with a cogged conveyor. Im guessing it would remain still thru several half lifes of ozone. And thats a long time in ozone years.
Larry

Oh I see, you are adjusting the parameters so that it can't possibly take off. I was attempting to show that even if you interpret the original question incorrectly an airplane (albeit modified to account for a challenging situation) will take off from this conveyor belt. All planes are built for specific tasks. There is no do all plane. Engineers design planes to operate in the specific environments encountered to accomplish specific tasks. Changing the environments just makes it a little harder.

Acceleration is instantaneous (you can't have motion without it). The magnitude of acceleration and resulting velocity takes time.

 

[patrick_g]

If you make folks think that they are thinking they will like you but if you actually do make them think they won't!

(Don't recall the cite for the paraphrase/plaigerphrase)

This thread has been a real kick even though my humor went unappreciated (and mostly unrecognized) and even drew some comments that were "ungracious."

Reading this has been nearly as much fun as dealing with folks with yet another take on a perpetual motion machine.

Pat

 

[Egon]

At least "The Fence" was not made of Razor wire Pat!!

 

[CharlieTR]

Hope I'm not repeating someone else, have been away and not read entire thread.

Seems to me that most practical way to duplicate the conveyor belt is to prop a plane up off the ground so wheels not touching the grnd.
Can it fly? Most of the ones I know would not.
Can a plane be build that will, yes I think so.

Take an Radio Control hobby plane,for example.
Hand launch it, most of them you must throw forward at least a little.
Some you can just let go.

Someone mentioned tire pressure and take-off distance, that seems to prove that wheels on the ground matter a good deal.
And that plane on the MCB still aint movin, so no flyin.

 

[joerocker]

Charlie,

You're missing a point. Being on the conveyor is NOT the "exact same" as holding it in the air and letting go. You need to support it's weight until it achieves enough AIRSPEED to create lift over the wings.

A better way to think of it would be to suspend it on a string and THEN try to take off...of course it would.

The point many of us are trying to make is that the speed of the ground hs no bearing on whether the plane takes off. The tires can be turning a million RPM and it won't matter. What IS important is airspeed and that is achieved irrespective on ANYTHING the ground is doing.

Quit thinking of a car on a dyno sitting there in a stationary position while the rear wheels spin wildly. Think instead of an aircraft engine in a test stand creating thousands of pounds of THRUST trying to rip itself out and go flying.

 

[turnkey4099]

Charlie,

You're missing a point. Being on the conveyor is NOT the "exact same" as holding it in the air and letting go. You need to support it's weight until it achieves enough AIRSPEED to create lift over the wings.

A better way to think of it would be to suspend it on a string and THEN try to take off...of course it would.

The point many of us are trying to make is that the speed of the ground hs no bearing on whether the plane takes off. The tires can be turning a million RPM and it won't matter. What IS important is airspeed and that is achieved irrespective on ANYTHING the ground is doing.

Quit thinking of a car on a dyno sitting there in a stationary position while the rear wheels spin wildly. Think instead of an aircraft engine in a test stand creating thousands of pounds of THRUST trying to rip itself out and go flying.

YIes, that is the whole problem. They are ignoring the major amount of thrust the engine is imparting to the airframe (not to the belt). To remain stationary with respect to the ground:

a.the engine cannot be running.

or

b. Something has to magically do away with some major wind being blasted back by the prop or jet.

Harry K

 

[MossRoad]

YIes, that is the whole problem. They are ignoring the major amount of thrust the engine is imparting to the airframe (not to the belt). To remain stationary with respect to the ground:

a.the engine cannot be running.

or

b. Something has to magically do away with some major wind being blasted back by the prop or jet.

Harry K

A. The engine can be running. I've stood next to plenty of planes that were running, brakes off, not going anywhere.

B. It is called wind, just like a blow dryer. Your hand doesn't take off.

Think of the conveyor as sucking it to the ground.

 

[turnkey4099]

A. The engine can be running. I've stood next to plenty of planes that were running, brakes off, not going anywhere.

B. It is called wind, just like a blow dryer. Your hand doesn't take off.

Think of the conveyor as sucking it to the ground.

Okay, now picture the engine running _at take-off power_. What is happening to that energy? All of it is being applied to the airframe, non to the belt. What is keeping the plane from being pulled through the stationary air?

Harry K

 

[joerocker]

MossRoad,

You're KIDDING right? I SURE hope so!

Stand behind a jet when it's sitting at the end of the runway and applies full throttle and you'll end up being blown quite a distance. Maybe killed. I've seen it flip trucks passing too close behind a jet engine.

You were kidding right?

Give the blow drier enough power and it will flail around wildly "trying" to take off, your hand won't fly unless it's powerful enough to lift your entire body. Which is EXACTLY what an airplane/jet engine IS. It's powerful enough to move the plane fast enough to eventually take of.

You were KIDDING right?

A helicopter is nothing more than a plane that takes off straight up. Would a "magic conveyor belt" stop a helicopter? It's NOT the ground or anything on the ground that affects takeoff.

I KNOW you were kidding...