“... munch, munch, munch...”

That’s the sound of me eating crow.

The plane will fly.

With the light of a new day I looked upon this thread again and immediately saw my error. Somehow I had convinced myself that the magical conveyor belt had been set up to cancel the forward speed of the plane by going in the opposite direction at ANY speed that was deemed necessary. I was envisioning the belt zipping along at incredible speeds, thus my concern with shredded tires and melted wheel bearings. This is incorrect. The scenario clearly states that the conveyor belt would go the SAME speed as the plane in the opposite direction. Oops, that’s quite different. I was wrong, wrong wrong.

Okay, I’ve got to level with you guys. I wasn’t thinking clearly the past couple of days. My girlfriend’s two kids were with their father this weekend, and that gave Anne and I a rare opportunity to spend some “adult time” together. Sorry, but my brain was probably low on oxygen all weekend as most of my blood was being diverted elsewhere!

quote Originally posted by Cliff Pennock: "This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Is clearly states that if the plane moves in one direction at speed X, the belt moves in the opposite direction at speed X. And nothing else. The belt will never move at a speed greater than the plane's speed. What's so difficult to understand about that?

Actually, you're both right depending on the understanding of the question. As you point out... the belt tracks & matches the exact "speed" of the aircraft. But it never defines or qualifies the variable which is the planes speed. Is it matching it's ground speed, or air speed?

If it's understood that the belt matches the ground speed of the plane - it will take off. (this is the most reality-based and common view of the question).

If it's understood that the belt matches (and thus zeros) the airspeed (through acceleration & resistance in the contact patch & related components such as tires/bearings, etc). No actual airspeed would occur - and thus no lift... and no flight. But this is extremely unrealistic (at least when looking at the capabilities of any existing belt).

quote Originally posted by Patrick: Okay, I’ve got to level with you guys. I wasn’t thinking clearly the past couple of days. My girlfriend’s two kids were with their father this weekend, and that gave Anne and I a rare opportunity to spend some “adult time” together. Sorry, but my brain was probably low on oxygen all weekend as most of my blood was being diverted elsewhere!

If you could spend some rare "adult time" with your GF, what the hell were you doing posting here?

quote Originally posted by MinnGreenGT: Actually, you're both right depending on the understanding of the question. As you point out... the belt tracks & matches the exact "speed" of the aircraft. But it never defines or qualifies the variable which is the planes speed. Is it matching it's ground speed, or air speed? If it's understood that the belt matches the ground speed of the plane - it will take off. (this is the most reality-based and common view of the question). If it's understood that the belt matches (and thus zeros) the airspeed (through acceleration & resistance in the contact patch & related components such as tires/bearings, etc). No actual airspeed would occur - and thus no lift... and no flight. But this is extremely unrealistic (at least when looking at the capabilities of any existing belt).

Close, but no cigar. The magic conveyor belt would have to actually cancel out the flow of air over the wings, by blowing air from back to front, effectively cancelling the vaccum created on top of the wings by air flowing from front to back. The conveyor is only trying to counter the forward movement of the plane by manipulating the speed of the TIRES, which is irrelevent to whether the plane would lift off or not. I think the guys who insist that the plane won't take off are hung up on the (false) premise that the tires of the plane provide locomotion for the planes forward motion, which is inaccurate. The plane uses AIR to move itself, which is uneffected by the fictional conveyor.

Someone explain how with no wind you can have airspeed without ground speed on takeoff or ground speed without airspeed.
Not possible.

The conveyor can't possibly effect EITHER of those, since it can't possibly prevent the plane from moving forward. Go back to the roller skate analogy on the treadmill.

[This message has been edited by Taijiguy (edited 12-05-2005).]

Bear in mind that I agree that the plane would takeoff if the belt was matched to the ground speed of the aircraft...

quote Originally posted by Taijiguy: Close, but no cigar. The magic conveyor belt would have to actually cancel out the flow of air over the wings, by blowing air from back to front, effectively cancelling the vaccum created on top of the wings by air flowing from front to back. The conveyor is only trying to counter the forward movement of the plane by manipulating the speed of the TIRES, which is irrelevent to whether the plane would lift off or not. I think the guys who insist that the plane won't take off are hung up on the (false) premise that the tires of the plane provide locomotion for the planes forward motion, which is inaccurate. The plane uses AIR to move itself, which is uneffected by the fictional conveyor.

...if the belt were designed to negatively match the airspeed (keeping it at zero all the time) the belt would have to accelerate (probably exponentially) to increase/maintain the drag created by the contact patch - again, to keep the airspeed at zero (if it were capable of that, then the system would never allow a measurable air speed - therefore no vaccuum would exist).

It's not about the tires being driven - it's actually about the drag created by the tires & rotating assembly (measured by the weight of the aircraft pushing down on the contact patches). If they truly created no drag or resistance, then we'd be able to push any plane (be it an ultra lite, or a loaded 747) and it would roll indefinitely.

Basically what I'm saying, is that it's all about how you define the planes speed (ground vs air) - and how you define the abilites of the belt to negatively match (and possibly negate) that speed. It's unrealistic to say that any belt is capable of this... but that's the point of the question

quote Originally posted by Taijiguy: The conveyor can't possibly effect EITHER of those, since it can't possibly prevent the plane from moving forward. Go back to the roller skate analogy on the treadmill.

Sure it can. Assume the skate is standing still on a treadmill that's not running. Without some form of forward power on the skate, when activated the treadmill will kick the skate off the back... courtsey of gravity & friction/rolling resistance!

[This message has been edited by MinnGreenGT (edited 12-05-2005).]

quote Originally posted by Steve Normington: If you could spend some rare "adult time" with your GF, what the hell were you doing posting here?

I'll be 50 years old this month. My refractory time isn't what it used to be.

Again, airspeed and ground speed are the same on takeoff unless you introduce a wind factor which was not in the original question. so no matter which you use it will be the same.

quote Originally posted by MinnGreenGT: Bear in mind that I agree that the plane would takeoff if the belt was matched to the ground speed of the aircraft... Sure it can. Assume the skate is standing still on a treadmill that's not running. Without some form of forward power on the skate, when activated the treadmill will kick the skate off the back... courtsey of gravity & friction/rolling resistance!

The forward power is provided by the prop cutting through the air, NOT a factor the treadmill is designed to counter. The other factors yo're trying to introduce, such as rolling resistance, are issues the plane is designed to deal with in the first place, so they wouldn't have any effect in this scenario. Hence, since the prop is pushing the plane, the conveyor can't possibly counter the ground/air speed, as the conveyor isn't acting on any part of the plane that is FIXED or in any way reative to the speed or movement of the plane.

[This message has been edited by Taijiguy (edited 12-05-2005).]

If I look at it with the understanding that the plane is doing everything it would normally do as if it were getting ready to take off- engines running, propellers doing what it would normally do, with the exception that the track underneath is keeping the plane stationary while it goes through this process... then I would agree that the plane would take off. If it is a jet engine whose purpose is to push the plane through the air to create the vacuum needed for flight instead of the propellers doing thier job of pulling air over the wings, and the aircraft didn't move, then I would say that the aircraft wouldn't take off. Since that wasn't made very clear in the question, I excuse my self from owing anyone an apology.

quote Originally posted by Taijiguy: ...the conveyor can't possibly counter the ground/air speed, as the conveyor isn't acting on any part of the plane that is FIXED or in any way reative to the speed or movement of the plane.

...except for the (very real & measurable) resistance to the ground - which isn't totally negated in the equation.

I agree, It's minimal, but without totallying ignoring that variable - it does have some (albeit small) effect on the system.

quote Originally posted by MinnGreenGT: ...if the belt were designed to negatively match the airspeed (keeping it at zero all the time) the belt would have to accelerate (probably exponentially) to increase/maintain the drag created by the contact patch - again, to keep the airspeed at zero.

"...keeping it at zero all the time..." That's where I went wrong. That's NOT what it states in the original scenario.

quote This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction).

MinnGreenGT, step back from the keyboard for a sec. I think you’re stuck in the same groove I was earlier with this topic.

I don’t think there’s any difference between airspeed and ground speed in this scenario. So let’s just drop that from the equation.

As the plane starts to move forward, the belt moves at the same speed in the opposite direction. This does NOT prevent the plane from moving forward, it just makes the wheels spin twice as fast. Yes, there is more friction, but not enough to slow the plane’s progress to any significant degree. As the plane picks up forward momentum, the belt also picks up momentum in the opposite direction. Again, the actual air/ground speed of the plane is not adversely affected by the conveyor belt, the plane continues to accelerate forward, and the wheels continue to spin twice as fast as the forward speed of the plane. This simply continues until the plane reaches lift off speed and flies off into the sunset.

[This message has been edited by Patrick (edited 12-05-2005).]

I agree 100% (and stated that in my 1st post) - that the plane will fly, based on the way most of us interpret the question.

I am/was simplying trying to show the infinite possilibity that the other people see when looking at the equation... it is possible for a belt with no properties grounded in reality (maximum speed especially) - to slow and possibly even counteract the forward momentum of the plane. Sure, it might have to make the belt go 1000mph to keep the plane from making forwad progress at 10mph... but that possilibity exists in a limitless equation. And as noted, it does somewhat step outside (although not entirely) of the intention of the question.

From a purely mathmatical & scientific perspective - the question does not contain enough defined variables to make a 100% accurate statement. But taking "reality" as we know it into account... it's a pretty simple question.

How did I miss this thread before. Its a bit late, but I gotta post, it's aircraft related...

The only difference between the conveyer and no-conveyer scenario would be that with the conveyer, the wheels would be spinning at twice the RPM at liftoff than they would without the conveyer. The conveyer cannot cancel the thrust of the engines unless the pilot locks up the brakes.

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My house is almost done, and my 85 GT wants more power! Soon to be - 3800SC!

Check out my Fiero project page!

quote Originally posted by MinnGreenGT: ... it is possible for a belt with no properties grounded in reality (maximum speed especially) - to slow and possibly even counteract the forward momentum of the plane.

100% agreed.

This was a lot more entertaining than the usual political debates.

quote Originally posted by Cliff Pennock: I truly can't believe people still think the plane won't fly. I rest my case - no explanation, calculation or scientific proof will make them think otherwise.

Cliff,
You are now at the same point I was earlier in this thread. I gave up.
Happy Fieroing.

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Ron
Freedom isn't Free, it's always earned.
My imagination is the only limiting factor to my Fiero. Well, there is that money issue.

quote Originally posted by Helo-mech: The conveyer cannot cancel the thrust of the engines unless the pilot locks up the brakes.

See, it's totally broad statements like this, that totally disregard the nature of physics - that make me post repeated on the infinite possibilites The wheels/tires/running gear do create some resistance, and increasing the speed of the ground would generally increaste that resistance (although still small).

It's just something I don't like people completely ignoring from the equation. At least aknowledge gravity & resistance (no matter how small).

Hmmm... must be a byproduct of having the author of your calc-based-physics text... also be your instructor... who also happens to be a top nuclear physicist at the university.

quote Originally posted by Patrick: This was a lot more entertaining than the usual political debates.

Yeah... I actually read this one through - and responded (as opposed to going back to the main menu and double checking that certain types of threads were disabled ).

[This message has been edited by MinnGreenGT (edited 12-05-2005).]

quote Originally posted by MinnGreenGT: The wheels/tires/running gear do create some resistance, and increasing the speed of the ground would generally increase that resistance (although still small). It's just something I don't like people completely ignoring from the equation. At least aknowledge gravity & resistance (no matter how small).

I know what you mean. I was trying to cover that way back at the bottom of page two!

quote Originally posted by Helo-mech: How did I miss this thread before. Its a bit late, but I gotta post, it's aircraft related... The only difference between the conveyer and no-conveyer scenario would be that with the conveyer, the wheels would be spinning at twice the RPM at liftoff than they would without the conveyer. The conveyer cannot cancel the thrust of the engines unless the pilot locks up the brakes.

Helo-Mech,
Don't even bother trying to explain, I guess you have to understand how and why an aircraft flys, some of the non-flyers here obviously don't. Every Pilot and Crew member on the forum has tried to explain it to the non-believers. I try to stay out of discussions I don't understand and learn from those that do. In this case, 12 years of test flying helicopters and several hundred hours of stick time in fixed wings obviously doesn't qualify me. Other experienced aviation persons, John Stricker and others have tried to explain it. Some folks you can't convince. BTW, we really didn't visit the moon either.

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Ron
Freedom isn't Free, it's always earned.
My imagination is the only limiting factor to my Fiero. Well, there is that money issue.

[This message has been edited by blackrams (edited 12-05-2005).]

quote Originally posted by blackrams: Don't even bother trying to explain, I guess you have to understand how and why an aircraft flys, some of the non-flyers here obviously don't. Every Pilot and Crew member on the forum has tried to explain it to the non-believers. I try to stay out of discussions I don't understand and learn from those that do. In this case, 12 years of test flying helicopters and several hundred hours of stick time in fixed wings obviously doesn't qualify me. Other experienced aviation persons, John Stricker and others have tried to explain it. Some folks you can't convince. BTW, we really didn't visit the moon either.

Why so negative? As far as I can tell from having read the entire thread pretty closely... even those who were most adament about the "No-Fly" theory have since been won over by the factual data!

I guess I don't understand your "some folks you can't convince" attitude?

Sorry about that, didn't mean it to sound that way, just my perspective I guess.

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Ron
Freedom isn't Free, it's always earned.
My imagination is the only limiting factor to my Fiero. Well, there is that money issue.

I love lamp

quote Originally posted by Wolfhound: Running on a tread mill is not the same thing. Thats the same as a axle powered plane, an idea that was abandoned early on after people laughed at them and called them puddle jumpers. Now if you put on roller skate and a backpack with a prop and a hang glider. It flys

This conveyer has a control system that tracks the plane speed and [b]tunes the speed of the conveyer to be exactly the same

Right, the airplane is doing 60 and the wheels are doing 120 because the conveyor is doing 60 in the opposite direction. yeah, the airplane will fly because it's moving farward.

Yeah, axle powered planes & subs with screendoors went the way of lead and cast iron balloons.

Bored with the new 'girl' in your life already, Bill, or just your fingers getting sore!!! !!
Nice to see you back, posting in your unique style again!!
Nick

quote Originally posted by fierofetish: Bored with the new 'girl' in your life already, Bill, or just your fingers getting sore!!! !! Nice to see you back, posting in your unique style again!! Nick

neither

quote Originally posted by MinnGreenGT: ...if the belt were designed to negatively match the airspeed (keeping it at zero all the time) the belt would have to accelerate (probably exponentially) to increase/maintain the drag created by the contact patch - again, to keep the airspeed at zero (if it were capable of that, then the system would never allow a measurable air speed - therefore no vaccuum would exist).

I understand where you're going, but I think that you would really have to do some mental gymnastics to make the original question reflect this particular scenario. Even assuming the question was referring to airspeed, it clearly states that the belt was tuned to *match* airspeed, not negate it. In this scenario, if the plane is moving forward at x knots, the belt is moving backward at x knots. Given this understanding, what friction that exists could be easily overcome.

Theoretically, if such a conveyor system were available that could overcome the thrust of the engines simply by turning the wheels on the plane fast enough...it would have to be moving at an unfathamable rate to overcome the thrust of the engines simply by increasing the friction on the wheel bearings. At such a speed, could the constant movement of the belt create enough air movement to create lift on its own?

quote Originally posted by AndyLPhoto: I understand where you're going, but I think that you would really have to do some mental gymnastics to make the original question reflect this particular scenario.

Yup But remember, I'm simply pointing out where others are coming from - and what they are "seeing" in the question.

quote At such a speed, could the constant movement of the belt create enough air movement to create lift on its own?

Honestly... I'm really not sure as to what kind of airflow a belt would create at that scale & speed

[This message has been edited by MinnGreenGT (edited 12-06-2005).]

quote Originally posted by naskie18: A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). The question is: Will the plane take off or not?

if the plane is only moving relative to the conveyor but not what is outside the conveyor.. then is it really moving? because the conveyor has to be moving an equal amount in the opposite direction..

so relative to the land if the plane is traveling 100mph east and the conveyor is traveling 100mph west - it satisfies both criteria -

so i vote yes the plane can take off if it goes fast enough and there is enough air density present

edit to add: an airplane does not use drive wheels - it does not care what the ground speed is - it only moved relative to the air and it uses the air to push itself around.. the conveyor would only make the wheels spin fast as the airplane moved through the air

[This message has been edited by Kohburn (edited 12-06-2005).]

Came up for air. You never used a snorkel??

John Stricker

quote Originally posted by Steve Normington: If you could spend some rare "adult time" with your GF, what the hell were you doing posting here?

quote A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). The question is: Will the plane take off or not?

If the planes engine were turning it's wheels (like a car) and the conveyor were rolling in the opposite direct at exactly the same speed then the planes motion relative to the surrounding air would be zero just like the car on a dyno. No airflow = no lift = it stays on the ground.

If the planes engine generates thrust against the surrounding air (prop or jet it does not matter) then the aircraft will react with an equal and opposite motion and move thru the air. Thus, all things being equal it would fly.

However, The aircraft would have rolling resistance thru its wheels, thus as it moved forward thru the air, the conveyor would react in the oposaite direction and 'drag it back' as it were do to friction. So long as the conveyor could react quickly enough to the aircrafts initial forward motion the aircraft would never gain enough speed through the air to generate enough lift to get of the ground. Thus it would not fly since it could never atain sufficient airspeed to free itself from the conveyor.
however I think it unlikely that such a conveyor could react instantly to the aircraft acceleration, thus the aircraft would alway be slight ahead of the conveyor, eventually allowing it to gain enough airspeed to take off.

It all depends on weather you are considering such things as resistance, inertia and reaction time of mechanical systems or not within the proble,
Basically your question is incomplete.

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Dave E

www.ltlfrari.com

quote Originally posted by FIEROPHREK: I cannot believe this thread has 4 pages The airplane will be able to fly. The propeller creates the force to move the aircraft forward. The conveyor belt cannot stop the aircraft from accelorating forward because it will just spin the aircraft "WHEELS" faster, big whoop. If there is no force physically holding the aircrafts feusalage from accelorating ( the conveyer does not ) it WILL accelorate. When the aircraft reaches it's determined minimum takeoff airspeed ( with flaps or with out) The aircraft will fly . The conveyor belt is doing nothing but spinning the tires, the tires DO NOT drive the aircraft forward the propellor does . The conveyor affects the speed of the tires which it turn has NO effect on the forward motion of the aircraft (unless brakes are applied). In short the aircraft will accelorate like normal and it will fly in normal fashion.

What he said ^ ^ ^ ^ ^ ^ ^ except page 7 . The friction generated by the wheels rolling at a greater speed will not overcome the engines ability to accelorate the aircraft. Just think any modern fighter must attain a very high forward airspeed to fly. Those wheels and bearings are no differant ( except for size ) than a small cessna type aircraft. Yet these big heavy fighters can fly with no problem. The rolling resistance will increase slightly but it will have no significant outcome on the aircrafts forward speed, and as soon as the aircraft breaks the deck the wheels don't mean sh*t.

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HARDCORE SBC CRONIE AND PROUD OF IT ! GOT TQ ?

[This message has been edited by FIEROPHREK (edited 12-06-2005).]

It would be no different than replacing a planes wheels with new ones of half the circumference.
It would still fly.

quote Originally posted by Patrick: “... munch, munch, munch...” Somehow I had convinced myself that the magical conveyor belt had been set up to cancel the forward speed of the plane by going in the opposite direction at ANY speed that was deemed necessary. I was envisioning the belt zipping along at incredible speeds, thus my concern with shredded tires and melted wheel bearings.

You were trying to pull a James Kirk as he did with his starfleet academy test. Changed the rules a bit. Oh, and--

"Too funny for words Patrick."

I believe it would make no difference if your initial supposition had been true--that is that the conveyor could run even faster than the aircraft was moving. One of the 1st things I did to prove to myself I was looking down the right road, was to go turn our variable speed conveyor up as high as it would go and place a toy car on it-as soon as I got to work. Regardless of how much weight I pressed down on the car, it still took less than a fingertip's pressure to push it along against the motion of the conveyor.

quote Originally posted by maryjane: I believe it would make no difference if your initial supposition had been true...

On that we don't yet agree, but I gave my reasons for not thinking straight last weekend.

quote Originally posted by Patrick: On that we don't yet agree, but I gave my reasons for not thinking straight last weekend.

And danged good reasons they were too!!!

Edit to learn to spell.
(To? TOO!

[This message has been edited by maryjane (edited 12-06-2005).]

A plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).
The question is:

Will the plane take off or not?

YES
I read the first couple posts and then a couple on page 7 to see if you were all still actually on the same subject.I'm sure somewhere in all these pages someone has said this already.

Given parameters of the question say
the plane moves in one direction. So it does move. Full circle is that if the plane does not move in the opposite direction then the belt doesn't compensate in reverse. So it is kind of a faulty question to begin with. Not logical.

So regardless of the planes actual speed the belt speed is regulated by the speed of the plane moving in the opposite direction.
The wheels on the plane do no create the energy needed to move the plane in that direction they are merely bearings.
The only way the belt could stop the plane from moving would be to exceed the mechanical limits of the tires turning. If that were to occur then the they would act as brake and skid due to the force of the prop or turbine or jet..
The plane could be on skids and take off of skis it breaks down to friction and the faster the plane moves the less friction there will be. But that is getting into more details than the question itself allows.

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PLAY HARD-DIE FAST
The only difference between saints and sinners is that every saint has a past while every sinner has a future.

Oh, God... not again...

The question states the plane is moving. The conveyor belt can spin in the opposite direction all it wants, but the plane is moving forward, therefore has wind at the wings, therefore can attain lift, therefore can fly.

The conveyor belt moving in the opposite direction only makes the wheels on the plane spin faster.

The propulsion of the plane forward is not made (and wasted) through the wheel-to-conveyor belt connection. Instead, the propulsion of the plane forward is made through the thrust-to-atmosphere connection.

so does anyone still think it would not fly?

quote Originally posted by buddycraigg: so does anyone still think it would not fly?

Probably