Black_Jesus
Not everyone has outstanding logic skills.... fact of life.
Chevyaudio
5,000+ posts
:poof:
I dont see how that is possible, because if the belt and the wheels are travleing at the same speed that would cancel out, there fore the plane is sitting still, with no ground or air speed
Chevyaudio
5,000+ posts
:poof:
ok think of it like this, you are on a treadmill on a bike. If you pedal the bike where you and the treadmill are cancelling out, is there wind rushing through your hair...NO, so therefore no airspeed
Black_Jesus
10+ year member
The Unexpected
the wheels dont move the plane, the engines displacing air does, jesus man.... this is like teaching someone who doesnt understand english how to write english literature
Black_Jesus
10+ year member
The Unexpected
ok ok heres something youll understand
get a bike, a treadmill, and a rocket pack
get on the bike, start the treadmill, pedal to keep yourself on the treadmill
turn on the rockets, and get a face full of drywall
then come back here and say it wont fly
I said earlier it depends (there are way too many variables not specified), but maybe I should have said all the above.
However, to prop up those who voted no, consider the following: The problem as stated specifies speed not velocity, hence there need be no forward velocity (read the belt is dragging the plane back at the same rate the plane is attempting forward progress). No movement of the airplane relative to fixed ground - no lift, no flight.
For the "it will fly" crowd, if you assume low friction between belt and aircraft body, i.e., wheels with good bearings, a reasonable assumption, and equate speed with velocity (not scientifically true, but then I'm a physicist and so...); then the aircraft's wheels will be rotating at a rate that is approximately equivalent to that at twice take-off velocity - the plane's speed in one direction, the belt's in the other - but there's still enough forward progress to take off & fly normally.
And finally, for those who somehow fell in-between (or couldn't make up their mind) assume the coefficient of friction between the belt and aircraft body was sufficiently high (the problem doesn't specify wheels with good bearings anywhere that I read) such that the velocity was low, then the plane could lift and fall back down due to stall speed considerations.
BTW, I have a low post count because I mostly lurk - and this is one of two audio forums I visit to learn.
Finally, the argument rages among scientific types, but I think the general consensus is that the air flow over and under the wing with pressure differential causes lift is old thinking. Lift (vertical thrust) IMO has as it's primary source a rotational torque applied to the wings. Why? Look at pics of contrails coming off a wing, or think about how a sailing boat with a rotating cylinder (and no sails) is able to move.
However, to prop up those who voted no, consider the following: The problem as stated specifies speed not velocity, hence there need be no forward velocity (read the belt is dragging the plane back at the same rate the plane is attempting forward progress). No movement of the airplane relative to fixed ground - no lift, no flight.
For the "it will fly" crowd, if you assume low friction between belt and aircraft body, i.e., wheels with good bearings, a reasonable assumption, and equate speed with velocity (not scientifically true, but then I'm a physicist and so...); then the aircraft's wheels will be rotating at a rate that is approximately equivalent to that at twice take-off velocity - the plane's speed in one direction, the belt's in the other - but there's still enough forward progress to take off & fly normally.
And finally, for those who somehow fell in-between (or couldn't make up their mind) assume the coefficient of friction between the belt and aircraft body was sufficiently high (the problem doesn't specify wheels with good bearings anywhere that I read) such that the velocity was low, then the plane could lift and fall back down due to stall speed considerations.
BTW, I have a low post count because I mostly lurk - and this is one of two audio forums I visit to learn.
Finally, the argument rages among scientific types, but I think the general consensus is that the air flow over and under the wing with pressure differential causes lift is old thinking. Lift (vertical thrust) IMO has as it's primary source a rotational torque applied to the wings. Why? Look at pics of contrails coming off a wing, or think about how a sailing boat with a rotating cylinder (and no sails) is able to move.
it WILL fly. For anyone who doesnt understand why it will, read this^^^ link.
the only force the belt puts on the plane is the extra friction from the wheels spinning twice as fast.
Logikalliquid
10+ year member
CarAudio.com Elite
What about jet engines? The thrust is generated behind the wings instead of in front of the wings on a prop driven plane so there would be no air movement over the wings and no lift, correct?
While that's a good comforting feeling, common sense (which should always be noted) dictates that plane who's bearings were bad enough that it would have any notable effect on the foreward thrust of the engine would have never made it to the runway in the first place. Either due to someone saying "Hey! That planes wheels are ****ED UP!" or the simple fact that they would probably be so bad that the plane simply would not have be physically able to taxi out to the runway.
Hey if you don't agree, just ignore me I'm just an HVAC technician...
Please read my first post in this thread.... I explained it assuming that it was a jet.
Logikalliquid
10+ year member
CarAudio.com Elite
Ooops, read that article and forgot about your explanation. Got it.
Chevyaudio
5,000+ posts
:poof:
Is the plane moving just fast enough to keep up with the treadmill?
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