riddle

RidinRails

they were in a dsm and it burst into flames and blew up andthey both died.

Afsil80

XJHEAD wrote:
It will take off

No it won't.

Don't start with me on this one, either. Ask Faber.

EDIT: I'll make it quick and painless.

Unless there is sufficient windspeed to lift the aircraft off the ground, it will not leave the pavement. Wheel speed has nothing to do with it. As an aircraft mechanic, they teach you that the landing gear is there for the sole purpose of supporting the aircraft as it is on the ground, and during take off and landing.

However.

An airplane can run it's engines at full throttle and go nowhere. Every plane I have witnessed take off at Grand Forks AFB, RAF Mildenhall and Al Udeid AB will always power their engines to the max, and apply full brakes. When the brakes release, the plane moves forward with a pretty decent amount of force. Riding on a civilian passenger jet won't show that because of the seat cushions. Riding in a KC-135 will show you that, because you sit on the side of the jet, and it throws you back like a subway train would, but with more force.

If the wheels are spinning, and the fuselage is not moving, no lift will take place. There has to be airspeed working against the leading edge of the wing for the bernouilli effect to work. If it's sitting on a conveyor belt, it will not move. Period.

? This user is from outside of this forum

AFSil80 wrote:
No it won't.

Don't start with me on this one, either. Ask Faber.

EDIT: I'll make it quick and painless.

Unless there is sufficient windspeed to lift the aircraft off the ground, it will not leave the pavement. Wheel speed has nothing to do with it. As an aircraft mechanic, they teach you that the landing gear is there for the sole purpose of supporting the aircraft as it is on the ground, and during take off and landing.

However.

An airplane can run it's engines at full throttle and go nowhere. Every plane I have witnessed take off at Grand Forks AFB, RAF Mildenhall and Al Udeid AB will always power their engines to the max, and apply full brakes. When the brakes release, the plane moves forward with a pretty decent amount of force. Riding on a civilian passenger jet won't show that because of the seat cushions. Riding in a KC-135 will show you that, because you sit on the side of the jet, and it throws you back like a subway train would, but with more force.

If the wheels are spinning, and the fuselage is not moving, no lift will take place. There has to be airspeed working against the leading edge of the wing for the bernouilli effect to work. If it's sitting on a conveyor belt, it will not move. Period.

What people fail to see is that it says the conveyor belt moves backwards at the same speed as the plane moves forward....basically the wheels spin twice as fast because of this and so long as the wheel bearings don't overheat and seize up before the plane generates enough airflow over the wings to achieve lift, the plane will fly. PERIOD.

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http://fargostreet.com/forums/showthread.php?t=5245&highlight=plane+conveyor+belt

Think about it this way if you are driving a motorcycle with a side car on it at 50MPH and the conveyor is ONLY on the side car you can still drive the motorcycle at 50MPH, however the sidecars wheel(s) will be traveling 100MPH. Same principal applies here. The planes motors providing thrust would be the motorcycle in above analogy and the planes wheels would be the side car. It is very possible for the plane to take off.

3_Series

The one thing I don't get is what the wheels have to do with anything, so they are moving 100mph, how is that moving any air over/under the wings?

Edit: Or in other words, how is the airplane moving forward relative to its static spot on the ground? How do the wheels moving at some speed have anything to do with lift?

I see it as like a treadmill. If you are running at 7mph, and the tread is going backwards at 7mph, you are in fact staying in the same spot relative to the ground, no matter how fast your feet are going.

XJHEAD

Engine thrust is propelling the craft not the wheels

Afsil80

XJHEAD wrote:
Engine thrust is propelling the craft not the wheels

Lift has nothing to do with how much thrust. Different aicraft require different amounts of thrust per weight.

It's all about the windspeed hitting the leading edge.

So again, if the wheels are freerolling and the conveyor belt is doing the same, the plane won't move. The wheels keep the airplane supported until it builds up enough airspeed for the bernoulli effect to take place.

If it can't hit that speed, and it won't while it sits on a belt that can keep up, there will be no forward motion.

Afsil80

nissankingcab wrote:
I see it as like a treadmill. If you are running at 7mph, and the tread is going backwards at 7mph, you are in fact staying in the same spot relative to the ground, no matter how fast your feet are going.

Exactly!

There is no wind flowing against you as if you were running on a track! Therefore, lift cannot occur!

Afsil80

XJHEAD wrote:
Engine thrust is propelling the craft not the wheels

I never said it was.

However, the wheels are relative to the aircraft's speed. It's an odd situation, because they are directly involved because of their purpose in takeoff, but at the same time, they aren't the determining factor in flight since they have nothing to do with the aircraft's airflow, which causes flight.

Afsil80

Oh, and I am off work now for the weekend. I have no plans since I am on standby.

If it takes me creating MS paint masterpieces to illustrate what is in my head, so be it. You have to think out of the box on this, and a little knowledge of aircraft helps. Faber presented this problem to me last night, and he'll tell you, I went on for the better part of an hour or so, debating with myself and reading the shit on MNSportCompacts. When I woke up, I stood firm in my beliefs that it cannot get off the ground.

PSiedTSi

AFSil80 wrote:
Exactly!

There is no wind flowing against you as if you were running on a track! Therefore, lift cannot occur!

Yes, but Peter, the wheels do not create any thrust of any kind. Think of it like this: Before the landing gear retracts, the wheels are spinning by the wind movement, although not as fast as say the treadmill will make them spin, they are still moving in the same fashion and will theoretically increase with wind speed but the plane will be unbothered. If the plane starts moving, which it will, it will take off. Yes, it won't take off without moving forward, but I don't think thats what people are trying to prove. If they are, then thats a totally different story and yes you are right. I think you might be trying to prove the wrong thing. If a runway was a HUGE treadmill, it will take off. The wheels will not provide enough resistance to keep it from moving.

Afsil80

I honestly don't know EXACTLY what I'm trying to prove, but regardless, my final argument is this:

No windspeed, no lift.

But for the sake of boredom, I will go as long as I must.

24valvenotak

a harrier doesnt need to be moving forward at all to take off, its all about thrust. with enough of it, it will move forward because hey, three pieces of rubber are no match for 90000lbs of thrust

RidinRails

exactly what mitch said, what conveyor belt can move as fast as a jet?

Afsil80

Think about a glider.

How does it move?

It has no mechanism to provide thrust.

Afsil80

97slowgsx wrote:
exactly what mitch said, what conveyor belt can move as fast as a jet?

Don't think of it like that.

Think objectively, that there IS a conveyor belt that can keep up.

? This user is from outside of this forum

god damnit.....

Yes, wheelspeed has NOTHING to do with the aircraft taking off, it is its FORWARD MOVEMENT (or rather the air rushing over the wings) that causes it to lift off. On an aircraft speed is not measured at the wheels either, it is measured as air speed (the speed the plane is moving through the air) so if a plane is moving forward through the air (with wheels still rolling on ground) at 25mph and the conveyor belt turning in the OPPOSITE DIRECTION at 25 mph it DOES NOT stop the plane dead in its tracks BECAUSE the wheels do not generate the forward movement, nor do they negate any forward movement if a force is being applied to them opposite of the movement of the aircraft, it will just cause them to spin approximately twice as fast as normal. It is because the wheels have no affect on a planes forward movement that the airplane can in fact lift off when the plane is moving forward at the appropriate speed. NOWHERE in the riddle does it say that the airplane remains stationary in relation to the ground, it states that as the plane travels forward, the conveyor belt spins backwards at the same rate, but the backwards travel of the conveyor belt has little/no affect on the planes ability to move forward since it is pushed forward by its jets/propellor/whatever and does not get its forward drive by applying power to the wheels. Again, the airplane does NOT remain stationary, it is in fact moving forward and therefore is able to take off.

XJHEAD

AFSil80 wrote:
Lift has nothing to do with how much thrust. .
Yes, you are correct there. The engines are pushing the A/C forward the tires are not making it go forward.

AFSil80 wrote:
It's all about the windspeed hitting the leading edge..
I think you better do a little more research on lift.

AFSil80 wrote:
So again, if the wheels are freerolling and the conveyor belt is doing the same, the plane won't move. ..

Let me ask you this, how will the conveyor even start to rotate if the plane has not even moved forward, explain that one to me??

AFSil80 wrote:
The wheels keep the airplane supported until it builds up enough airspeed for the bernoulli effect to take place...

I agree that is one reason, the other is that it would create alot of havoc during landing w/out them...

AFSil80 wrote:
If it can't hit that speed, and it won't while it sits on a belt that can keep up, there will be no forward motion.

It will hit that speed..

Let us look at this way, say you put a bicycle on a treadmill, and you push it forward and the treadmill begans to speed up at the same rate as the tires, not at the rate you are pushing it. With this concept are you stating that you will not be able to push the bike off the treadmill pushing forward????

AFSil80 wrote:
You have to think out of the box on this, and a little knowledge of aircraft helps..

I think 5 years in the Marine Corps working on the flight line troubleshooting F-18 fighter jets maybe makes me a little bit qualified here. Not just watching them take off and land like you and listening to other people who have no clue as to what the fuck they are talking about...

Enough said,, probally not let's hear it...

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Colin

the plane will take off, the converyor belt will simply make the wheels spin faster realative to the speed of the forward motion of the jet and the reverse motion of the conveyour belt.

because the thrust of the jet engine is pushing the plane forward, and the wheel axels are free spinning, once the applied friction of the wheels to their axels is negated by equal force from the thrust, the plane will make forward motion until it reaches speed to make lift, then if will fly.

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