Will it take off?

[oldenough]

Gilbert wrote: Geeeez, 16 pages of debate for this moronic question,... unfreaking believeable.

The most moronic thing of all is the FACT that after sixteen pages there are still people who think the plane wont fly. Here's another FACT... it WILL.!!! FACT.

P.s we are now at seventeen pages[]

[Champagne taste beer budget]

Cool. It just occured to me the Navy's been missing a real opportunity here. These steam catapaults they're using are expensive, dangerous and hard on the planes. *THEY DON'T NEED THEM!!!*

We install a conveyor belt on the flight deck. We put a plane on the belt. We fire up the engines, and start the belt moving backwards. We throttle up the engines and speed up the belt until the belt is going about 500 ft/sec (which ought to be above Vlof for just about any plane I know of), with the plane sitting there furiously burning fuel, stationary on the deck. Then, we *STOP THE BELT!!!* The plane launches forward immediately at 500 ft/sec, safely taking off with a huge safety margin. This is, like, *SO COOL...*

Way to go Klipsch BBS! Making the world safe for technology!

Ray, since you are obviously more experienced and informed about aircraft than I, I have a question for you.

Just how DO these planes apply the force generated by the jet engines to the wheels? Is it a rope and pully system, or gears, or some sort of chain and sprocket set-up?

I know one thing, I sure hope I know I never get stuck somewhere like Antartica depending on a plane to get me out, cause heaven knows, if you need those wheels to apply some force somehow against that slippery ice, the next group of explorers is going to find you frozen as a popsicle.

[sputnik]

......Neither of these components can occur for the conveyor scenario described, because the engines thrust will be negated by the speed of the conveyor.........

.........Geeeez, 16 pages of debate for this moronic question,... unfreaking believeable.

Gilbert,

How does the speed of the conveyor negate the engine's thrust? I can't wait to hear your answer.

16 pages, because people don't analyze the problem correctly and/or don't bother to read previous posts before they jump in and restate obvious points about thrust and lift.

Still waiting for an answer. [sn]

Here is something else to think about. If our "will not take off" friends are right, then reverse thrust couldn't slow a plane down after landing. Someone tell the admiral.

[Fish]

Funny stuff guys.All I want to know is can I be Pilot?,last plane I got on crashed with my cash and I was lucky to get out with my a$$.[:-*]

[oldenough]

Surely someone amongst us can set up a simple experiment, i do have a number of R/c planes but no treadmill. I did think about going to the local Gym, but somehow i dont think they would take kindly to me cranking up a glowplug engine at 15000 rpm. Plus those big old weight lifters would probably laugh there well developed pecs off, wondering why i was trying to prove something so plainly obvious.[]

[sputnik]

Surely someone amongst us can set up a simple experiment, i do have a number of R/c planes but no treadmill. I did think about going to the local Gym, but somehow i dont think they would take kindly to me cranking up a glowplug engine at 15000 rpm. Plus those big old weight lifters would probably laugh there well developed pecs off, wondering why i was trying to prove something so plainly obvious.[]

I beginning to really like this crude video demonstration these kids did.

http://videos.streetfire.net/player.aspx?fileid=35E964D9-38DB-4EFD-BE8D-D6BA1A43A06B

[oldenough]

I guess the "wont fly crowd" would'nd find that demo convincing enough. Even though it is crude you can see that the vehicles progress down the "conveyor" is not impeded. But i think a more realistic approach could be the death of this .

[sheltie dave]

Ray cottoned on to the nexus of the crisis.

The thrust from the jet engines is the motive force to drive the plane forward. Make the plane a computer controlled F-22, and have the same computer slaved to a servo drive on the conveyor, since lots of people are hung up on the wheel thingie.

As the thrust from the jet engines drives the plane forward, the linked servo actuates and accelerates the conveyor in the identical opposite direction. The plane stays at the fifty yard line, as previously noted.

Formulaes of interest are...

Velocity = delta distance/ delta time

Acceleration = Velocity final - velocity initial/time

Force = mass x acceleration

With the plane still at the original position, there is no change in distance, so velocity is zero. This makes acceleration zero. It will also make net force zero.

The thrust of the jet engines in an actual takeoff create some sympathetic venturi flow lift over/under the wings, but the largest portion is generated by the acceleration down the runway, with the resultant air flow and d/p. If this were not true, total wing area needed for liftoff and flight would be miniscule, as the jet engines could do all the work.

Thrust, when charted on graph paper, will show a relative negative sigmoid (s) curve, while lift will show a relative positive sigmoid curve. Add the two together, and at points above the minimum force required to generate sustained flight, you should be able to take off. Remove either component, and you won't get off the ground with a normal jet.

All engineered jet fighters have flight equations generated, which allows for computer simulations, and also now allows some fighters to have computers fly the buggers. My brother's stupid admiral would hand calculate some of these in his wet behind the ears days, but now he lets a computer model do most of the grunt work. He will forward the conveyor belt idea over to the Air Force, however. [] It should save bunches of money.

[oldenough]

Slightly off topic, i happen to be listening to P. McCartney & Wings "Band on the Run". I had forgotten what a good toe tapping album it is.

[oldenough]

Sheltie, out of concern for the Admiral and the security of his job i would suggest that he not show his total lack of knowledge about this to his superiors. Although if he is an Admiral he has very few superiors to worry about. But that does means that us poor cannon fodder have a whole lot to worry over in the event that we have to follow this guy into battle somewhere.

[Ray Garrison]

Cool. It just occured to me the Navy's been missing a real opportunity here. These steam catapaults they're using are expensive, dangerous and hard on the planes. *THEY DON'T NEED THEM!!!*

We install a conveyor belt on the flight deck. We put a plane on the belt. We fire up the engines, and start the belt moving backwards. We throttle up the engines and speed up the belt until the belt is going about 500 ft/sec (which ought to be above Vlof for just about any plane I know of), with the plane sitting there furiously burning fuel, stationary on the deck. Then, we *STOP THE BELT!!!* The plane launches forward immediately at 500 ft/sec, safely taking off with a huge safety margin. This is, like, *SO COOL...*

Way to go Klipsch BBS! Making the world safe for technology!

Ray, since you are obviously more experienced and informed about aircraft than I, I have a question for you.

Just how DO these planes apply the force generated by the jet engines to the wheels? Is it a rope and pully system, or gears, or some sort of chain and sprocket set-up?

I know one thing, I sure hope I know I never get stuck somewhere like Antartica depending on a plane to get me out, cause heaven knows, if you need those wheels to apply some force somehow against that slippery ice, the next group of explorers is going to find you frozen as a popsicle.

joke

noun 1. something said or done to provoke laughter or cause amusement, as a witticism, a short and amusing anecdote.

Of *COURSE* it will fly. I've been saying that for 15 pages. I was just getting so frustrated the last few posts I was attempting a bit of levity. I still really like my roller coaster example of a few pages back. The treadmill example on the previous page was pretty good too.

If there's this much trouble with something as simple as a plane taking off while some surface moves beneath it, image what would happen if we asked a basic relativity question. Here's one. A meter stick if moving at nearly the speed of light parallel to a plane that lies beneath it. The plane is slowly rising towards the meter stick. There is a hole exactly one meter across in the plane. The plane and meter stick are converging such that, at the point when their positions cross, the center of the meter stick is at the center of the hole.

Now, from the meter stick's frame of reference, the hole has been relativistically forshortened, and is less than a meter across. It won't fit through. From the hole's perspective, the meter stick has been relativistically forshortened, and will fit through the hole with no problem.

What happens?

[Ray Garrison]

Just one more try at this. Suppose the plane is flying above the belt with wheels retracted. No matter how fast the belt goes in the other direction, the plane will still fly, right? Okay. Now, lower the gear, but keep flying. When the wheels touch the belt, the plane will continue to move forward, right? Okay. Now, throttle back bit by bit. As our airspeed slows, we will begin to transfer some weight to the wheels, until at some point we can say we're no longer flying, but taxi-ing (?spell?) really, really fast. But we're still moving forward, right? Okay. We could speed up and take off again, right? Okay. Now, repeat this process, each time slowing down a bit more, until we reach the point where we come to a complete stop (zero airspeed) before we start speeding up again. We are now at the starting point poised by the question. We can still take off, right? Hello? What's the frequency, Kenneth?

[sputnik]

Ray cottoned on to the nexus of the crisis.

The thrust from the jet engines is the motive force to drive the plane forward. Make the plane a computer controlled F-22, and have the same computer slaved to a servo drive on the conveyor, since lots of people are hung up on the wheel thingie.

As the thrust from the jet engines drives the plane forward, the linked servo actuates and accelerates the conveyor in the identical opposite direction. The plane stays at the fifty yard line, as previously noted.

Formulaes of interest are...

Velocity = delta distance/ delta time

Acceleration = Velocity final - velocity initial/time

Force = mass x acceleration

With the plane still at the original position, there is no change in distance, so velocity is zero. This makes acceleration zero. It will also make net force zero.

The thrust of the jet engines in an actual takeoff create some sympathetic venturi flow lift over/under the wings, but the largest portion is generated by the acceleration down the runway, with the resultant air flow and d/p. If this were not true, total wing area needed for liftoff and flight would be miniscule, as the jet engines could do all the work.

Thrust, when charted on graph paper, will show a relative negative sigmoid (s) curve, while lift will show a relative positive sigmoid curve. Add the two together, and at points above the minimum force required to generate sustained flight, you should be able to take off. Remove either component, and you won't get off the ground with a normal jet.

All engineered jet fighters have flight equations generated, which allows for computer simulations, and also now allows some fighters to have computers fly the buggers. My brother's stupid admiral would hand calculate some of these in his wet behind the ears days, but now he lets a computer model do most of the grunt work. He will forward the conveyor belt idea over to the Air Force, however. [] It should save bunches of money.

[^o)] Hmmmmm, let me adjust my tie and answer that.

[oldenough]

Hey Sputnik no need to SHOUT...lol...

[sheltie dave]

Heck yes, he'll work on getting the computer models updated as well...

There will be a bunch of bunny hoppin' planes in the next week.

Thrust = drag, if you boilerplate the model.

[Champagne taste beer budget]

Sorry, Ray.

I thought you were the guy I was sharing bat wings with down in the cave a few pages ago, but got all caught up and had to write a reply.

Glad to see you're still on the right, and correct, side. []

[Gilbert]

......Neither of these components can occur for the conveyor scenario described, because the engines thrust will be negated by the speed of the conveyor.........

.........Geeeez, 16 pages of debate for this moronic question,... unfreaking believeable.

Gilbert,

How does the speed of the conveyor negate the engine's thrust? I can't wait to hear your answer.

I gave it my best shot, please read below

16 pages, because people don't analyze the problem correctly and/or don't bother to read previous posts before they jump in and restate obvious points about thrust and lift.

first off, my opinion (mine) was requested for the question that was given. My opinion about what someone else thought was not asked; so I gave it, without any prior thought to what anyone else had to say, because it's irrelevant.

Still waiting for an answer. [sn]

Patience, and I'm sorry if my response was not speedy engouh for you, but I had to run to Lowes to buy some paint, and other niknaks. Then had to drive all the way down to the office to get a couple of books.

Here is something else to think about. If our "will not take off" friends are right, then reverse thrust couldn't slow a plane down after landing. Someone tell the admiral.

No need to think about landing, Landing is something completely different for this scenario. The fact that you introduce this new concept into the equation makes me wonder about your interpretation of the question. We (me and you) may be talking apples and oranges, and as a result, your getting overly excited for no reason. But, anyway, as I understood the question asked of us, it has to do with the planes ability to take off. Sorry if I'm sounding rude, because I'm not trying to be

With that said... sure, I'll play one more round, but please (and I respectfully request this, PLEASE), clear your thoughts about whatever point or hurdles you were previously trying to jump over or prove. Start with a clear mind, or clean sheet of paper, so to speak.

The one and only thing you & I must agree upon is the fundemental fact that forward airspeed is required to produce lift on the wings..... -hopefully, we're in agreement on this fact, and I believe we are.

Now, lets get to the question that was presented to us. Please correct me if I am mistaken, or if we are of differing opinions with respect to the question that was asked.

As I understood the question, there are 2 key pieces of information.....

1st KEY: There is a plane capable of developing an infinite amount of engine thrust.

2nd KEY: And the BIGGIE... This plane sits on top of a conveyor belt that has the magical ability to adjust it's speed in direct proportion to the planes forward engine thrust. As a result of the conveyors magical abilities, the planes does not move forward while at full thrust, its' speed relative to its' surroundings is zero, i.e. as thust increases or decreases, so too does the speed of the conveyor belt. Hence, offsetting (or negating) the movement of the plane relative to it's surroundings.

That is how I understood the question.... Are we in agreement?

If yes, then answer me this... Will the pilot feel the wind pressure if he/she was to stick his/her hand out the window? The answer, NO, because there is no relative motion, and hence no forward airspeed across the wing.

If no, then we're obviously not in agreement with respect to the question presented, and hence one of us (or both of us) obviously mis-intrpreted the question.

Oh, for what it's worth (probably not much) I am a pilot with just over 24yrs (750+ hrs) experience, and I think I have a fairly decent grasp on the theory of relativity. But that doesn't mean I understand coyotees question. So with that said, please don't beat me with a big stick for not interpreting the questions the same way you do.

Cheers, it's Saturday night, and I'm going to have a few beers before the big boxing match this evening.. Manny Pachiao versus Eric Morales... the 3rd and final match. If you like boxing, you gotta watch this one.

[Champagne taste beer budget]

a plane is standing on a movable runway( something like a conveyor).as the plane moves the conveyor moves but in the opposite direction.the conveyor has a system that tracks the speed of the plane and matches it exactly in the opposite direction.

the question is

will the plane take off or not?

(ps its been debated to death on other forums, its always fun to see how people present the theory behind there answer)

2nd KEY: And the BIGGIE... This plane sits on top of a conveyor belt that has the magical ability to adjust it's speed in direct proportion to the planes forward engine thrust. As a result of the conveyors magical abilities, the planes does not move forward while at full thrust, its' speed relative to its' surroundings is zero, i.e. as thust increases or decreases, so too does the speed of the conveyor belt. Hence, offsetting (or negating) the movement of the plane relative to it's surroundings.

That is how I understood the question.... Are we in agreement?

NO! We are NOT in agreement. The original question, shown above, nowhere states that the conveyors speed is in any way related to the the thrust of the engine. Instead it says the conveyor moves to match the speed of the plane. The thrust of the engine is NOT applied to the conveyor, it is applied to the surrounding air, or lack thereof. (Again, think space shuttle docking thrusters.)

Once everyone sees the question as I do, the RIGHT way, we can all go back to arguing about interconnects and subwoofer properties as God intended. []

(I do believe that the only reason there are 29,000 ongoing discussions on this particular question on the net right now is that both sides can be correct, dependant upon their point of view or assumed frame of referance.)

Mine, however, is still the right one. [A]

[sputnik]

Still waiting for an answer. [sn]

Patience, and I'm sorry if my response was not speedy engouh for you, but I had to run to Lowes to buy some paint, and other niknaks. Then had to drive all the way down to the office to get a couple of books.

Here is something else to think about. If our "will not take off" friends are right, then reverse thrust couldn't slow a plane down after landing. Someone tell the admiral.

No need to think about landing, Landing is something completely different for this scenario. The fact that you introduce this new concept into the equation makes me wonder about your interpretation of the question.................

Application of reverse thrust for an aircraft moving down the runway after landing is another way of viewing the same problem. If you're traveling down the runway after landing, you'e on a conveyor belt as far as the plane knows. If you're right, the motion of the runway relative to your plane should somehow impart a force to slow the plane down after you drop the power ["offsetting (or negating) the movement of the plane relative to it's surroundings" - as you put it] the same way you seem to think the conveyor imparts a force on the plane to oppose it's motion under power. There would be no need for additional braking actions after landing. Yes, I know that bearing friction and rolling friction will eventually slow the plane but that's not what we're talking about.

With that said... sure, I'll play one more round, but please (and I respectfully request this, PLEASE), clear your thoughts about whatever point or hurdles you were previously trying to jump over or prove. Start with a clear mind, or clean sheet of paper, so to speak.

The one and only thing you & I must agree upon is the fundemental fact that forward airspeed is required to produce lift on the wings..... -hopefully, we're in agreement on this fact, and I believe we are.

Now, lets get to the question that was presented to us. Please correct me if I am mistaken, or if we are of differing opinions with respect to the question that was asked.

As I understood the question, there are 2 key pieces of information.....

1st KEY: There is a plane capable of developing an infinite amount of engine thrust.

This was not stated in the problem nor is it necessary or relevant.

2nd KEY: And the BIGGIE... This plane sits on top of a conveyor belt that has the magical ability to adjust it's speed in direct proportion to the planes forward engine thrust. As a result of the conveyors magical abilities, the planes does not move forward while at full thrust, its' speed relative to its' surroundings is zero, i.e. as thust increases or decreases, so too does the speed of the conveyor belt. Hence, offsetting (or negating) the movement of the plane relative to it's surroundings.

That is how I understood the question.... Are we in agreement?

Noooo, this was the question that I asked you to answer. Again, how does the conveyor negate the movement of the plane? That is, how does the conveyor impart any substantial horizontal force on the aircraft that opposes the engine thrust?

The action of the conveyor at any speed or variation of speed is irrelevant to the motion of the plane because the wheel bearings isolate the plane from the action of the conveyor. The wheels just spin faster.

[Clarence]

......Neither of these components can occur for the conveyor scenario described, because the engines thrust will be negated by the speed of the conveyor.........

.........Geeeez, 16 pages of debate for this moronic question,... unfreaking believeable.

Gilbert,

How does the speed of the conveyor negate the engine's thrust? I can't wait to hear your answer.

I gave it my best shot, please read below

16 pages, because people don't analyze the problem correctly and/or don't bother to read previous posts before they jump in and restate obvious points about thrust and lift.

first off, my opinion (mine) was requested for the question that was given. My opinion about what someone else thought was not asked; so I gave it, without any prior thought to what anyone else had to say, because it's irrelevant.

Still waiting for an answer. [sn]

Patience, and I'm sorry if my response was not speedy engouh for you, but I had to run to Lowes to buy some paint, and other niknaks. Then had to drive all the way down to the office to get a couple of books.

Here is something else to think about. If our "will not take off" friends are right, then reverse thrust couldn't slow a plane down after landing. Someone tell the admiral.

No need to think about landing, Landing is something completely different for this scenario. The fact that you introduce this new concept into the equation makes me wonder about your interpretation of the question. We (me and you) may be talking apples and oranges, and as a result, your getting overly excited for no reason. But, anyway, as I understood the question asked of us, it has to do with the planes ability to take off. Sorry if I'm sounding rude, because I'm not trying to be

With that said... sure, I'll play one more round, but please (and I respectfully request this, PLEASE), clear your thoughts about whatever point or hurdles you were previously trying to jump over or prove. Start with a clear mind, or clean sheet of paper, so to speak.

The one and only thing you & I must agree upon is the fundemental fact that forward airspeed is required to produce lift on the wings..... -hopefully, we're in agreement on this fact, and I believe we are.

Now, lets get to the question that was presented to us. Please correct me if I am mistaken, or if we are of differing opinions with respect to the question that was asked.

As I understood the question, there are 2 key pieces of information.....

1st KEY: There is a plane capable of developing an infinite amount of engine thrust.

2nd KEY: And the BIGGIE... This plane sits on top of a conveyor belt that has the magical ability to adjust it's speed in direct proportion to the planes forward engine thrust. As a result of the conveyors magical abilities, the planes does not move forward while at full thrust, its' speed relative to its' surroundings is zero, i.e. as thust increases or decreases, so too does the speed of the conveyor belt. Hence, offsetting (or negating) the movement of the plane relative to it's surroundings.

That is how I understood the question.... Are we in agreement?

If yes, then answer me this... Will the pilot feel the wind pressure if he/she was to stick his/her hand out the window? The answer, NO, because there is no relative motion, and hence no forward airspeed across the wing.

If no, then we're obviously not in agreement with respect to the question presented, and hence one of us (or both of us) obviously mis-intrpreted the question.

Oh, for what it's worth (probably not much) I am a pilot with just over 24yrs (750+ hrs) experience, and I think I have a fairly decent grasp on the theory of relativity. But that doesn't mean I understand coyotees question. So with that said, please don't beat me with a big stick for not interpreting the questions the same way you do.

Cheers, it's Saturday night, and I'm going to have a few beers before the big boxing match this evening.. Manny Pachiao versus Eric Morales... the 3rd and final match. If you like boxing, you gotta watch this one.

are you guys really still debating this ridicioulus premise? for shame....