Airplane Flight Question - Page 4 - United Bimmer Community

**Red_Rocket** · 11-29-2005, 09:53 AM

according to the theory of relativity, the plane is going 0 m/s

and plus if there is no air flowing over the wings, they will not lift, no matter how hard the engines are pulling

simple physics, this is a no brainer

**celsdogg** · 11-29-2005, 11:29 AM

Quote:

Originally Posted by Dudesky

The definitive answer is no, the plane will not take off. It has nothing to do with wheels, skis, conveyor belts, engines, whatever. The fact that both the plane and the atmosphere are standing still is why it won't take off.

Lift is generated by way of the Bernoulli principle: as others here have stated, faster moving air = lower pressure, and slower moving air = higher pressure. The curve on the top of the wings causes air to move over it faster than below it, allowing the denser air below to support the wings in flight. Either the air has to move through the wings, or the wings have to move through the air. This applies to anything- birds, gliders, jets, helicopters, boomerangs, whatever.

That said, if the engines could move enough air through the plane, then it would rise in place. The problem is, engines are designed to create thrust to propel the plane forward, NOT to move air over and through the wings. The air they move in front of the aircraft goes right to the intake of the engines and out the back. And whatever ambient air it does move through is not enough to overcome the weight of the aircraft. The physical forward motion of the plane through the atmosphere, or the atmosphere moving across the wings is what gives it lift, not the engines, and movement via theory or postulation does not work. It has nothing whatsoever to do with the plane's speed or what it's sitting on- it can lift off at 0mph, so long as enough air is passing through its wings, and you certainly don't need a conveyor belt for that to happen. Just because the ground is moving doesn't mean the atmosphere is moving along with it.

Think of it this way: take the engines out of the equation . . if you kept a glider in place and revved up that conveyor to 11 million mph, the damn thing would still never take off.

If the theory was even plausible, why don't we have conveyor belts on aircraft carriers? If it were possible, that would save so much precious deck space over the steam catapult systems! If you still don't agree, then produce proof by concrete example of how your theory works. It's nothing more than a silly riddle

i read this whole thread to see if someone would finally bring up the bernoulli principal. . . by name. . .

nick_318is · 11-29-2005, 11:40 AM

Allright I'm going with the its not going to take off crowd, it needs airspeed across the wings to take off, and assuming there is no wind how the fuck is it going to get off the ground. Here is just a simple example, I Bike (with a trainer, stationary so i can spin on my own bike) and have run on a treadmill. When doing either of these things you should get real sweaty real fast because there isn't any wind going past you to cool you, where as if your actually out moving through space you will create apparent air flow (even if its a day without any wind) and feel wind and it keeps you from getting as sweaty. And from what i remember of Highschool physics you need airspeed to create lift on the airfoil. This is just my thoughts, if someone can prove that there will be air moving across the wings sufficent enough to create enough lift for the plane to take off then i will consider changing my mind.

**voca** · 11-29-2005, 11:54 AM

ok, I thought about it and I'm recanting what I said earlier.

everyone who says it won't take off, is also saying that it won't move. but I'm telling you it will move. if the planes engines propell it to 70mph and the conveyer goes the same speed in the opposite direction, the conveyer is just going to spin the wheels of the plane at 140mph, but the plane will still move 70mph relative to the ground because it's being propelled from the air not the ground.

so, try to visualize the situation. the plane will gain speed and will take off.

good question. I'm going to send this to my dad. he loves airplanes and physics.

**01Mike330i** · 11-29-2005, 12:32 PM

1. I can't believe I just read this entire thread.
2. I now know more about lift, and thrust than I did before starting to read this thread..
3. We all really need to get out more.
a. I too believe that the plane will not fly as it's stationary on the conveyor, and there is no lift on the wings.

And finally...

4. No matter how you put it...I still hate to fly.

**komodo** · 11-29-2005, 01:04 PM

Quote:

Originally Posted by voca

ok, I thought about it and I'm recanting what I said earlier.

everyone who says it won't take off, is also saying that it won't move. but I'm telling you it will move. if the planes engines propell it to 70mph and the conveyer goes the same speed in the opposite direction, the conveyer is just going to spin the wheels of the plane at 140mph, but the plane will still move 70mph relative to the ground because it's being propelled from the air not the ground.

so, try to visualize the situation. the plane will gain speed and will take off.

That's what I'm saying.

Everyone saying it won't take off is also assuming the plane isn't moving (and thus no wind for the airfold), however I think the plane IS moving. The wheels are spinning freely, but the engines are exerting thrust in the air, pushing the plane forward from the wings. The wheels are going to spin freely, so in response to the engines pushing the plane forward, they'll be spinning twice as fast, but not exerting force in the opposing direction to stop the aircraft. Therefore it will take off like normal, with MAYBE 1 or 2 miles per hour less speed (so it might take a few more seconds before it takes off), from the friction alone, but the difference of friction on freely spinning wheels (which are DESIGNED NOT to cause drag on the object they're on, which is why they roll....).

**bitcore** · 11-29-2005, 01:23 PM

Jesus christ you guys are crazy. The question is poorly wored and dosn't explain everything fully.

Trick question. If the plane is moving (fast enough for regular takeoff), then the mentioning of the conveyor is bullshit meant to confuse you, and it will take the fuck off.

It dosn't, however, explain what it's moving in relation to... the conveyor or the air. If it's moving in relation to the conveyor, then it's real world velocity is 0.

**komodo** · 11-29-2005, 01:29 PM

^^ It's not a trick question, people are trying to figure out IF the plane WOULD move.

**bitcore** · 11-29-2005, 01:29 PM

It says it's moving. No need to divulge into sicence of lift\propulsion, etc...

**donald1476** · 11-29-2005, 01:34 PM

Quote:

Originally Posted by donald1476

Oh and here's more proof http://www.avweb.com/news/columns/191034-1.html

Umm... It has been done. Check link.

**Dudesky** · 11-29-2005, 05:20 PM

^^^Okay, now I get it. I stand corrected. I can't imagine the engines creating that much air movement, but that article can't be disputed.

**delmarco** · 11-29-2005, 11:36 PM

wow....
just wow!

how many UB members does it take to figure out if a plane that is standing still is moving?

riddle me that!

witeshark · 11-29-2005, 11:54 PM

If the turbo fans are running at speed enough to cause lift grade airflow over the wings/lift surfaces - they will soon over heat!

**donald1476** · 11-30-2005, 12:25 AM

Quote:

Originally Posted by delmarco

wow....
just wow!

how many UB members does it take to figure out if a plane that is standing still is moving?

riddle me that!

How many delmarcos does it take to make the dumbest comments. .999...!

**exjarhead328** · 11-30-2005, 08:24 AM

One variable that hasn't been discussed is when cocktail service starts.