Would be freakin cool if this actually ended up on mythbusters It's posted on their forum so we'll see what happens. btw I emailed this to my gym partner who works at JPL.. his response: wheels? falk wheels, we'll strap a rocket on there and launch the plane, wheels, and whole conveyor belt into orbit But yes his consensus was that it would easily achieve flight given the power of any reasonably sized plane.
BMW.Williams - you know the problem! Yes, I agree with your answer, but you understand why I didn't pose the whole question here. One guy on another forum I'm registered with got so heated up about this he stormed off and never came back, after spending literally *ages* concocting the most way out theories imaginable, whilst some very patient folk kept trying to explain to him that it was actually very simple... mxblue: I agree getting posted on mythbusters would be cool, except it would a bit of fame that you wouldn't want to admit to nice young ladies at parties. [Sadly, my only other bit was getting pictured in a hifi mag in the UK after reviewing some kit, which I don't tend to volunteer, either!!] I should have spent my youth playing guitar and now be a rock star but no! I had to be 'good' and do all my Physics exams in school and then a degree, didn't I??? Like the comments from your JPL buddy!! Maybe he should chime in here! G'night! Rich.
man it's funny you's still don't get that the plane cannot move forward WHATSOEVER if the original rules are adhered to. if it can, then the rules are broken and the answer is invalid. simple!
notice that for those who say the plane will fly the answer is very simple, however those who say the plane won't fly the answer is very complex. that there should point out that sometimes the answer is as simple as the nose on your face
Actually, I called one of my engineer friends, who's currently getting his masters in rocket science (aero) at a well known Institute in Massachusetts. I described the question to him, and after 10 seconds of thinking, his response was, "Absolutely not."
Actually, the word is "salon." I've PM'ed the troublemaker, I mean, thread's starter an email addy - hopefully, the recipient (*wiggles eyebrows*) will, in turn, answer the question at some point in time. IMHO: absent any measurable static or dynamic air pressure, it won't fly.
Exactly, which is why an 11yr old gets it but others refuse to let it go... Ohh Ohh if you adhere to the rules it's impossible.... yeah well i'm failing to see which "rule" we broke, but w/e. And hey I would have no problem telling people my post got on mythbusters, hell I wouldn't mind being ON the show, that red head broad is HOT The ladies don't much care if your into dorky smart guy stuff, all they see is more $$$ in the future, lol. I invited Paul (jpl friend) to come over here, so we'll see if he makes it. Kid has a pretty nice M3 so i'm sure he makes his way to the forums.
mxblue23, Great idea. One of my favorite shows. Whatever the results, it would be fun to watch with this thread of background and discussion (that most viewers would not have).
The rule I think that you're breaking is that the conveyor isn't moving at the same speed as the plane, when the "rule" says that its moving at the same speed of the wheel. This mystical conveyor belt isn't like a self-powered treadmill or a free spinning dyno, where the reaction of the plane's forces causes it to turn. The way that the question is worded states that it is designed to magically equal the wheel speed, at any given time.
oh brother, I'm still waiting to hear a reasonable explination of how a conveyor belt under an airplane will in any way effect it's ability to fly. Wheels still roll, plane still moves down the runway just fine... I'm about to go build a 50ft conveyor belt and have a model plane haul azz off the end of it Untill someone can actually post a legit description of how doubling the wheel speed will somehow prevent a plane from flying, i'm over this. And thats exactly what it boils down to. all you are doing is changing the wheel speed of the plane. If you guys with masters can't figure that out, then god help us all.
here are some basic physics of it: Comparison: Linear vs. Angular Kinetics Linear Angular Inertia : mass (m) moment of inertia (I) Cause of motion : force (F = ma) torque (T = Ia) Momentum : M = mv H = Iw
try again here Comparison: Linear vs. Angular Kinetics linear kinetics Inertia: mass (m) Cause of motion : force (F = ma) Momentum :M = mv Angular Kinetics Angular Inertia : moment of inertia (I) Cause of motion : torque (T = Ia) Momentum : H = Iw
Which changes the conveyor belt speed in an equal amount. I'm still pondering teak's response. That's the only one so far that actually has me reconsidering my position.
Yes I completely understand that. And being that the wheels on the plane are free spinning, it makes no difference what so ever. When you finally understand that the wheels have ZERO effect on the propulsion of the plane it's much simpler. In all reality it doesn't matter if the conveyor belt is traveling 4x the speed of the plane in the opposite direction, The engines on the plane will still drive it just the same. It may slow it down a miniscule amount from the rotational friction of the tires spinning so fast but thats it. I really don't see how it's so difficult to understand? It's an airplane, it operates directly in correlation to wind speed, assuming the wheels are free to spin they don't effect it in any way. Planes land with tires that are not spinning when they are traveling hundreads of mph, if the runway was traveling at doube that speed in the opposite direction it wouldn't magically suck the plane to the ground would it? Or launch it to the moon now would it? Man some smart people are really dumb at times, or just so caught up in over analyzing things they miss the most basic stuff. here's a real brain teaser for ya. How do you get an elephant inside a refrigerator? Will post the answer shortly.
SO? the conveyor belt is practically IRREVELANT. It's just there to mess with your head. Wheels on a plane are relatively free spinning, and even with the immense weight there isn't THAT much friction. Look, if one of those little trucks can push a 747 around, which is basically just overcoming the rolling friction, not fighting aerodynamics etc. What makes you think that by even tripling that force, that it would prevent the aircraft from taking off? If he throttles that jet up it will drag that little truck down the runway and fly to hawaii with it swinging below.
Ding ding ding! That's the whole point! The wheels are free to spin, but the conveyor cancels out their forward motion.
And you thought we had a lot of input... http://community.discovery.com/groupee/forums/a/tpc/f/9701967776/m/7451937218/p/1
The plane takes off. Ground speed doesn't matter, it is all about the air speed. Sure the plane isn't moving relative to the ground, but the air is. It's too early for me to set up the partial differential equation (and I don't do them on Sunday mornings as a rule), but all you have to remember is the no slip at the wall condition (i.e. v(x=0) = 0). You will get a velocity gradient in the air. Move the treadmill fast enough and you'll get a nice defined flow (it will be very complex, but it will be stable). Guess what, you're going to have a pressure differential on the wing because of the flow and the plane will take off when the buoyant force on the wing is greater than the force of gravity. I did well in fluid dynamics... EN Ph.D. Chemical Engineering
Ahhh but the wheels are NOT propelling the plane now are they? for the one billionth time Its NOT a wheel driven vehicle. you can spin the wheels in any direction you want and it will have zero effect on the travel of the aircraft.
But the plane isn't moving, relative to the ground, until sufficient lift is generated, right? I could accept that. I did terribly in fluid dynamics, yet somehow I still analyze drainage basins and open channel flows.
The position of the plane on the treadmill is kept the same only when the plane is keeping a constant velocity, which the treadmill matches. Once it starts to accelerate (when thrust is applied), it will move forward along the treadmill. The plane will move foward because of the thrust pushing more air out the back. The wheels will spin faster because the plane is moving foward and the treadmill speeds up to match the wheels speed at the same time. The treadmill doesn't keep the plane stationary because the wheels are connected to NOTHING. Edit: To further try to simplfy this, a plane does not need ground to accelerate. All it needs is air.
