Stealth, no one assumes the plane can somehow fly if it can't roll forward on the runway. That is not the argument here. The argument is that it can roll forward on a conveyor runway system.

Is that much understood?

The plane must be able to move forward in order to generate lift, we get that. The idea that the plane is "sitting still" on a conveyor runway is what is being discussed here.

The plane will not "sit still" even on a conveyor runway.

I'll use the "little red wagon" once again, it shows the difference between "freewheel" and "drivewheel" the best way I know to demonstrate it.

Imagine a long conveyor, like those in an airport. Now right beside this long conveyor, is a sidewalk. You have a little red wagon. You place the wagon on the conveyor. You stand on the sidewalk beside the conveyor.

You start pulling the wagon along, you walking on the sidewalk, the wagon rolling along right behind you , off to your right, on the conveyor.

The conveyor is off at this point, but but it can be turned on to roll either way, and the speed of the conveyor can be modulated.

So, the conveyor is off, you are walking along at 3 mph, walking on the sidewalk, pulling the wagon along right behind you , except it is just off your right, rolling along on the conveyor.

At this point, the speed of the wagon is 3 mph. (Because you are the force that is propelling the wagon along, and you are walking 3 mph)

Now, someone turns on the conveyor, and sets the speed to 10 mph. Your walking speed is still 3 mph. What do you think the mph of the wagon is? Granted, the wheels are doing the equivalent of 10 mph, but isn't the wagon still just going 3 mph? (because the wheels are freewheeling)

Now, some one actually reverses the direction of the conveyor. Now it is going 20 mph in the other direction. But you are still walking along the sidewalk, pulling the little red wagon, at 3 mph. What speed is the wagon moving? Granted, the wheels are now spinning the other way at the equivalent of 20 mph. But what is the wagon doing? Isn't it still going forward at 3 mph?

This is just to demonstrate that since the wheels are freewheeling, and not the source of propulsion, it doesn't matter to the source of propulsion what the wheels are doing at what speed or even which direction they are rolling.

In the case of the airplane, the prop pushing air backwards is the source of propulsion, and it doesn't care what the wheels are doing.

Lets look at two things here: The speed of the wagon as it relates to the conveyor and the speed of the wagon as it relates to the sidewalk.

There were three differnet states...the wagon rolling along the fixed conveyor, the wagon rolling along the 10 mph forward rolling conveyor, and the wagon rolling along the 20 mph backwards rolling conveyor.

In each case, although the speed of the wagon may have changed in relation to the conveyor, it's real speed, the speed as it relates to the sidewalk, never changed. Because the force that makes the wagon move, the guy pulling it along who is walking on the sidewalk,(or the propellor or jet engine pushing air back) is not at all affected by the interaction of the wheels to the conveyor....does that make sense to you?

 

I watched it. That is way flawed. You cannot use that to bolster your argument. The conveyor isn't actually moving the same speed in the opposite direction as the plane is moving forward.

BTW< I'm talking jet engine, not prop engine, big differences in propulsion.

 

it doesnt matter if it Is flawed the speed of the belt is IRRELAVANT!!!!!!!! it could be moving 2000 mph in the oposite direction of a plane moving 100 mph forward, the plane is still moving forward, the ground speed of the plane would be 100 miles and hour in relation to the earth and 100mph indicated airspeed but the wheels would be spining at 2100mph

and jets and props while different still use the same form of propulsion to produce trust, they both accelerate air in one direction, ones just more powerful

 

Yes, I understand, the plane would be doing the same thing in the three senarios, but it wouldn't be creating lift since it wouldn't actually be moving forward. The OP's senario is that te conveyor matches the ground speed of the object aircraft as it tries to move forward. End result: The plane doesn't fly. No lift.

I walk on my treadmill I am walking forward but not actually going anywhere, gaining zero ground, no matter how fast I or the treadmill is moving.

 

Slap on some roller skates and an airboat prop to your back.

See what happens then

 

That plane on MB is not indicative of a life sized plane. You all know that.

 

Hell no. I don't really care about this that much! It is rather amusing to watch us all argue about nothing.

 

you dont go anyware because YOUR FORWARD THRUST IS DIRECTLY COUPLED TO THE GROUND YOU ARE WALKING ON. an airplanes forward thrust IS NOT, instead an airplanes FORWARD THRUST IS INDIRECTLY COUPLED TO THE Ground instead it is coupled to the AIR SURROUNDING IT

 

Either way, you're going to get forward thrust. It may take a lil more thrust to take off due to the friction caused by the spinning wheels, but you will move forward.

 

It depends upon how you are measuring the speed of the plane. If measuring it in relation to air or ground speed, of course it is going to fly. If measuring it in relation to a spot on the conveyor, it will never fly as it has a 0 ground and air speed. The question itself is so open ended that all answers are correct.

 

LOL.. It's the same people that believe the bible stuff that DON'T think the plane is taking off.

Even if you took the wheels off and dragged the spindles on the ground, the thrust created by the propeller will be more than the reverse direction of the conveyor belt.

 

I was trying to think of an example to help him understand and~

Put the airplane on pontoons. It is now in a river and you are on an ajacent bank. The river then starts flowing at 40 mph,the airplane is now drifting down river and it will take 40 mph thrust just to stay even with you on the bank. 0 airspeed


stealth you're tough and also right

 

But that isn't the question. Reread the question in post one.

 

Isn't this the same as if the plane was on wheels and on the conveyor?

 

Yes it takes off.