the new aircraft carriers...can't they be fitted with with conveyor belts instead of catapults
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plane on a conveyerbelt
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Posted 1 year ago #
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well the speedo was linked to the wheels in the delorean... so that would suggest maybe wheel speed/revs was enough?
ahhh but then in like BTTF 3 it flies...
shame.
Posted 1 year ago # -
well the speedo was linked to the wheels in the delorean... so that would suggest maybe wheel speed/revs was enough?
Are you sure?
ahhh but then in like BTTF 3 it flies...
shame
Doesn't it fly at the end of the first film - though admittedly this is when it has returned to the present from the future (that is to say once it had the hovering wheels upgrade)
Posted 1 year ago # -
Why so? (once you take the initial inertia out of the equation).
Tarp Direction: <----
Forces acting <---- are pulling the plane by the base of its wheels. Wheels can spin freely.
Forces resisting this, acting only on the plane, are inertia (as you said) plus I would suppose some slight drag from wind resistance, increasing with speed.
Forces <--- are obviously far greater than forces -->, but forces -> are only acting on the plane, so it has less total force acting in <- than the tarp and is free to spin its wheels.
Still don't see how this helps your argument.
Posted 1 year ago # -
yeh im sure its wheel speed based. speedo drive goes the centre of the hub.
shame tho, the flying has wrecked it.
Posted 1 year ago # -
Baby Robin on a conveyor belt?
Tried that one. It just falls out of the sky when it reaches the end of the conveyor belt......
Posted 1 year ago # -
speedo drive goes the centre of the hub.
Oh is the scene where they repair the speedo only in the directors cut?
shame tho, the flying has wrecked it.
That bloody Doc Emmett Brown; being all good at inventing stuff
Posted 1 year ago # -
So if the conveyor belt is moving at 25mph in this case, what speed would the plane be moving backward in your estimation with the engine turned off?
Next question. Are you agreed that the plane would have to apply some thrust to prevent it from going backwards in relation to a fixed point on the ground whilst on the conveyor belt (but not necessarily to actually move forwards in relation to a fixed point on the ground)?
Posted 1 year ago # -
So if the conveyor belt is moving at 25mph in this case, what speed would the plane be moving backward in your estimation with the engine turned off?
I dunno - lets say 24mph for arguments sake?
Are you agreed that the plane would have to apply some thrust to prevent it from going backwards in relation to a fixed point on the ground whilst on the conveyor belt
Yep.
Posted 1 year ago # -
Posted 1 year ago # -
For the aircraft the fly it needs to achieve (in this case) 25mph of forward airspeed over the wings. This could be achieved by tethering it to the ground at a fixed point in relation to the ground and blowing (either through wind or a big **** off turbine) air over the wings or on a still day moving the wings forward in relation to a fixed point on the ground at 25mph. Agreed?
If the aircraft is to apply EXACTLY THE SAME AMOUNT OF THRUST it required to JUST make this speed on a normal runway, how when impeded by the drag you acknowledged above will it reach the same 25mph?
Posted 1 year ago # -
well...it just needs a little more thrust to overcome the small amount of extra rolling resistance.
Posted 1 year ago # -
well...it just needs a little more thrust to overcome the small amount of extra rolling resistance.
And that is where the experiment was compromised. Obviously if the plane tanked it with huge amount of thrust it could easily take off, especially if you use an aircraft with such a low take off speed so the margins for error are so small. The true test is that the aircraft can take off without using any more thrust than the bare minimum required in normal conditions.
Posted 1 year ago # -
This is brilliant, when this thread is done can we ask it again?
Posted 1 year ago # -
If the aircraft is to apply EXACTLY THE SAME AMOUNT OF THRUST it required to JUST make this speed on a normal runway, how when impeded by the drag you acknowledged above will it reach the same 25mph?
Who said anything about "EXACTLY THE SAME AMOUNT OF THRUST"?
The question is simply "can it take off?"
It will need exactly the same thrust PLUS a tiny bit more to overcome the extra rolling resistance / wheelbearing drag (or it will require a slightly longer runway)
Posted 1 year ago # -
Who said anything about "EXACTLY THE SAME AMOUNT OF THRUST"?
The question is simply "can it take off?"
It will need exactly the same thrust PLUS a tiny bit more to overcome the extra rolling resistance / wheelbearing drag.
Sorry, but you entirely missed the point of the conundrum. Of course an aircraft can take off from a rolling runway if it uses more thrust - only a proper thicky could not work that out- think aircraft carier. It's if it required extra thrust which is the crux of the issue.
Posted 1 year ago # -
Of course an aircraft can take off from a rolling runway if it uses more thrust
Posted 1 year ago # -
If you thought that was the actual question you must have thought the rest of the world was proper stupid
Posted 1 year ago # -
Sorry, but you entirely missed the point of the conundrum
No, you have. Thrust is nothing to do with the argument. People imagine that the plane simply will not move - hence comments about "why don't we just replace runways with small conveyor belts". They picture a plane gaining 'speed' (ie groundspeed) on the conveyor, then magically taking off. Of course this won't happen, but the plane will just accelerate and take off as normal. People don't get it because they're idiots.
Posted 1 year ago # -
Now I know you're just trolling, convert.
Mythbusters state the myth as:
"An airplane cannot take off from a runway which is moving backwards (like a treadmill) at a speed equal to its normal ground speed during takeoff."
In one of those earlier threads I stated it as:
"If you put a plane on a very powerful, very long, very wide treadmill and fired up the engines, then would the treadmill operator be able to prevent the plane taking off by running the treadmill in the opposite direction?"
http://www.airplaneonatreadmill.com/ states it as:
"A plane is standing on a large treadmill or conveyor belt. 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). Can the plane take off?"
No mention of "EXACTLY THE SAME AMOUNT OF THRUST" in any of that.
Posted 1 year ago # -
"If you put a plane on a very powerful, very long, very wide treadmill and fired up the engines, then would the treadmill operator be able to prevent the plane taking off by running the treadmill in the opposite direction?"
Yes.
Posted 1 year ago # -
Posted 1 year ago # -
scuzz - Member
"If you put a plane on a very powerful, very long, very wide treadmill and fired up the engines, then would the treadmill operator be able to prevent the plane taking off by running the treadmill in the opposite direction?"
Yes.Umm no.
Posted 1 year ago # -
"If you put a plane on a very powerful, very long, very wide treadmill and fired up the engines, then would the treadmill operator be able to prevent the plane taking off by running the treadmill in the opposite direction?"
Yes.dear god
Posted 1 year ago # -
My theory: these threads are entirely populated by people who understand the question perfectly, but half of them are pretending they don't to wind up the other half.
Posted 1 year ago # -
Wheels are attached to planes. If you park a plane by putting the brakes on, and then throttle the engine up, the plane will not move.
The rolling resistance of a wheel varies with the square of the wheels' rotational velocity (consult any introductory dynamics text). As this velocity can be anything (the treadmill is very powerful), there will be a velocity with a rolling resistance which is greater than the thrust of the engines, just like the maximum friction from the tyre is greater than the thrust of the engines for the parked case.
Yes, everything will explode, and the rolling resistance coefficient is tiny (around 0.01), but since you asked...
Posted 1 year ago # -
Areoplanes take off because they have wings, right?
Just checking.
Posted 1 year ago # -
Oh Scuzz, please.....
I really don't know what to say.
Posted 1 year ago # -
ha ha ha
Posted 1 year ago # -
Wheels are attached to planes. If you park a plane by putting the brakes on, and then throttle the engine up, the plane will not move.
The rolling resistance of a wheel varies with the square of the wheels' rotational velocity (consult any introductory dynamics text). As this velocity can be anything (the treadmill is very powerful), there will be a velocity with a rolling resistance which is greater than the thrust of the engines, just like the maximum friction from the tyre is greater than the thrust of the engines for the parked case.
Yes, everything will explode, and the rolling resistance coefficient is tiny (around 0.01), but since you asked...
I don't know whether to laugh or cry
Posted 1 year ago # -
dont cry al. the dynamic coefficient of friction will tear the skin right off your face. it's in literally the most basic textbooks mate.
Posted 1 year ago # -
scuzz: yeah okay
I suspect that's why the other versions simply say the treadmill speed matches that of the plane.If we're allowing the treadmill to be driven close to light speed without anything exploding/melting then it might generate enough force from rolling resistance to hold back a plane at maximum thrust - though the treadmill would probably be displacing enough air backwards at that point that it would actually generate lift and of course a sonic boom at ground level might well launch the plane into the air anyway
Posted 1 year ago # -
What if we put superglue on the treadmill track?
Posted 1 year ago # -
miketually - Member
My theory: these threads are entirely populated by people who understand the question perfectly, but half of them are pretending they don't to wind up the other half.*applauds* \o/
Posted 1 year ago # -
the dynamic coefficient of friction will tear the skin right off your face. it's in literally the most basic textbooks mate.
Yes but what about the affect that wind resistance will have on those tear rolling down my face? will that be enough to stop the skin tearing action?
Posted 1 year ago #
Topic Closed
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