Author Topic: Can this airplane lift off? (Read 31267 times)

SEBNN · « **Reply #200 on:** April 05, 2009, 02:18:29 PM »

This question got 14 pages?

I'm a bit nervous to let some of you work on anything mechanical.

I'll put it this way:

If I hang a propeller on the back of my bike and allow it to spin freely with the wind while I ride, will the propeller make me fly?

Now discuss amongst yourselves. I'll be back at page 28 to check your answers.

DammitDan · « **Reply #201 on:** April 05, 2009, 02:58:57 PM »

No. I mean yes.

Markcb750 · « **Reply #202 on:** April 05, 2009, 03:00:13 PM »

Quote from: SEBNN on April 05, 2009, 02:18:29 PM

This question got 14 pages?

I'm a bit nervous to let some of you work on anything mechanical.

I'll put it this way:

If I hang a propeller on the back of my bike and allow it to spin freely with the wind while I ride, will the propeller make me fly?

Now discuss amongst yourselves. I'll be back at page 28 to check your answers.

Seriously

SEBNN · « **Reply #203 on:** April 05, 2009, 03:13:38 PM »

Quote from: shacolaid on April 03, 2009, 06:45:40 PM

Mea culpa everyone,

I admit I am wrong and yes it took two days and 13 pages to realize it. I called a pilot friend of mine and explained the question and very quickly he said yes the plane would take off. Sorry but I trust him more than most of you.

But as we were talking he said that if the plane landed on a conveyor belt going in the opposite direction of the wheels, the plane would stay in one place.

How's that for a new question!

Your friend is only half an idiot. Again, wheels spin free unless brakes are applied. If you step on the brakes you'll go backwards. If you don't step on the brakes, the plane drifts to a stop due to the forces of drag and friction until its forward motion relative to the ground is = to 0, and then it will begin moving backwards with the conveyor belt.

Please tell me your pilot friend relies on the auto landing system or was calling you from the pilot's lounge/bar at the airport.

sangyo soichiro · « **Reply #204 on:** April 05, 2009, 03:32:35 PM »

(Remember me...? I'm the guy that started this mess.)

There are two problems guys. One's easy, one's not so easy. I haven't made any claim as to what the answer is, but now that the easy version has been addressed, how about the other one?
Here

Duke McDukiedook · « **Reply #205 on:** April 05, 2009, 03:37:22 PM »

Quote from: SEBNN on April 05, 2009, 03:13:38 PM

Quote from: shacolaid on April 03, 2009, 06:45:40 PM
Mea culpa everyone,

I admit I am wrong and yes it took two days and 13 pages to realize it. I called a pilot friend of mine and explained the question and very quickly he said yes the plane would take off. Sorry but I trust him more than most of you.

But as we were talking he said that if the plane landed on a conveyor belt going in the opposite direction of the wheels, the plane would stay in one place.

How's that for a new question!

Your friend is only half an idiot. Again, wheels spin free unless brakes are applied. If you step on the brakes you'll go backwards. If you don't step on the brakes, the plane drifts to a stop due to the forces of drag and friction until its forward motion relative to the ground is = to 0, and then it will begin moving backwards with the conveyor belt.

Please tell me your pilot friend relies on the auto landing system or was calling you from the pilot's lounge/bar at the airport.

Aaaaaannnd.... let the personal attacks begin NOW.

masonryman · « **Reply #206 on:** April 05, 2009, 03:43:43 PM »

I still say flight is not so much about motion but pressure. If the propeller and the air foil and the flaps can create enough pressure under the wings to over come the weight of the plane in will lift off. A plane can fly stationary in to the wind, I have seen it.

Mark

Gordon · « **Reply #207 on:** April 05, 2009, 03:59:36 PM »

Quote from: masonryman on April 05, 2009, 03:43:43 PM

I still say flight is not so much about motion but pressure. If the propeller and the air foil and the flaps can create enough pressure under the wings to over come the weight of the plane in will lift off. A plane can fly stationary in to the wind, I have seen it.

Mark

Of course it can, but it's not flying because of the wind created by its own propeller.

In order for a plane's wings to create lift, it does need forward motion, but not motion in relation to the ground. It needs forward motion in relation to the medium that it gets its lift from, the atmosphere. All perceived motion is just movement in relation to other objects.

It may look, to a bystander on the ground, that an airplane flying into a strong headwind is stationary, but that's only in relation to the ground below it. In fact it's moving forward in relation to the air that it's flying through.

Markcb750 · « **Reply #208 on:** April 05, 2009, 04:04:57 PM »

If fact...There is no lift, there is only Drag.

Gordon · « **Reply #209 on:** April 05, 2009, 04:06:35 PM »

Quote from: Markcb750 on April 05, 2009, 04:04:57 PM

If fact...There is no lift, there is only Drag.

also, there is no spoon.....

seaweb11 · « **Reply #210 on:** April 05, 2009, 04:19:31 PM »

Here's my analogy question.

If you sat on your bike pulled on the front brake and did burn out would there be any wind in your face?

BlindJoe · « **Reply #211 on:** April 05, 2009, 04:25:06 PM »

Is there a fan in front of you?

seaweb11 · « **Reply #212 on:** April 05, 2009, 04:53:54 PM »

Nope, just a smile on my face as l look to the right and see a plane on a treadmill sitting full speed going no where beside me

Markcb750 · « **Reply #213 on:** April 05, 2009, 05:00:59 PM »

WOW!

No wonder they can sell us a "lite" cigarettes.

Gordon · « **Reply #214 on:** April 05, 2009, 05:05:10 PM »

Quote from: seaweb11 on April 05, 2009, 04:53:54 PM

Nope, just a smile on my face as l look to the right and see a plane on a treadmill sitting full speed going no where beside me

Did you also notice the rope tied to the tail of the plane that's keeping it from moving forward?

SEBNN · « **Reply #215 on:** April 05, 2009, 05:07:06 PM »

Quote from: seaweb11 on April 05, 2009, 04:53:54 PM

Nope, just a smile on my face as l look to the right and see a plane on a treadmill sitting full speed going no where beside me

I'd say something, but then I'll just get in trouble. All I can say is just keep on

and keep your seat in the upright condition during takeoff and landing.

SEBNN · « **Reply #216 on:** April 05, 2009, 05:16:59 PM »

To clarify, is the second question the same as the first except that now we need to consider the moment of inertia of the wheel/bearings/tire/etc?

If so, unless you have some very large tires on a very small plane, its still getting airborne. The tires are still only going to spin 2 times as fast as the planes relative speed to the round.

masonryman · « **Reply #217 on:** April 05, 2009, 06:21:50 PM »

Is it not the props job to move atmosphere, If not how does a helicopter fly/hover

SEBNN · « **Reply #218 on:** April 05, 2009, 07:04:24 PM »

Quote from: masonryman on April 05, 2009, 06:21:50 PM

Is it not the props job to move atmosphere, If not how does a helicopter fly/hover

Helicopters are so ugly the earth repulses them. Not technically flying, but it works for rotor-heads I guess.

333 · « **Reply #219 on:** April 05, 2009, 07:08:25 PM »

It's hard to tell whether some of you are really thinking this plane won't fly, or if you're just pulling our legs. I could go all the way, and just state how stoopid you might be,but...

First, the original question says nothing about anything being different except the runway. One MUST assume that it's a regular plane, with regular ball bearing wheels, and that no brakes are being applied during take off. There are no trick questions like "what weighs more, a pound of feathers, or a pound of iron".

Then, there's a video. Proving that take off is possible. Yes, there is a tarp instead of a conveyor belt, but the tarp actually has more drag in it's endeavor to move in the opposite direction, assuming a conveyor belt is on some sort of rollers.

I appreciate that some have used humor. ( I know there is no spoon). I, too, am scared that some of you work on your own bikes. Not counting the converts, about 1/4 of you guys just don't get it. You seem to be fixated on an idea that the wheels create the speed and motion used for flight. Or maybe the aircraft carrier thing in reverse. As someone pointed out, a carrier points into the wind for take off, so if you are thinking the conveyor belt is moving the surrounding air, I can see your point. And yes, the conveyor belt does have some drag affect on the air, but no where near enough to have a measurable affect on the wings.

And it is a props job to move atmosphere. It moves air to create thrust. If it doesn't move atmosphere(air) how does a helocopter work?

I think copters are cool, Sebnn. Remember the TV show, Airwolf?

Gordon · « **Reply #220 on:** April 05, 2009, 09:38:38 PM »

What's up with this tangent about propellers moving air? Of course propellers move air. Who said they don't?

masonryman · « **Reply #221 on:** April 06, 2009, 02:26:27 AM »

gordon

"Of course it can, but it's not flying because of the wind created by its own propeller. "

toycollector10 · « **Reply #222 on:** April 06, 2009, 02:56:26 AM »

The principle of flight is that when propeller thrust (or jet thrust) exceeds drag (form drag and induced drag) and when lift (generated by the wings) exceeds the weight of the aircraft, said aircraft will take to the air.

I learned that stuff as part of "Principles of Flight" as part of my Pilot Licence training years ago.

So the answer to the initial post is a big, fat, NO!

Retro Rocket · « **Reply #223 on:** April 06, 2009, 03:05:53 AM »

I cannot believe so many still don't get it. The conveyor makes no difference at all, the plane is still going to be drawn forward by the thrust produced by the propeller, the conveyor has no effect on this at all. Go back and look at the Mythbusters video, even the pilot thought the answer was NO.

Quote

The principle of flight is that when propeller thrust (or jet thrust) exceeds drag (form drag and induced drag) and when lift (generated by the wings) exceeds the weight of the aircraft, said aircraft will take to the air.

How can you say that and then say No?

Mick

Inigo Montoya · « **Reply #224 on:** April 06, 2009, 06:25:22 AM »

Some just have to see it in person to get it. Not everyone visualizes the same way. Most of us know the plane will take off. Some have to see it, as no airport in the world is going to go through the expense of building a runway conveyor belt, that wont happen!

News:

Poll

Can this airplane lift off?

Author Topic: Can this airplane lift off? (Read 31267 times)

Markcb750

masonryman

Markcb750

Markcb750

masonryman

masonryman