Plane on Conveyor Belt

[madmike2]

Looks like you can run that "experiment" in a variety of ways to get any answer you want..... The implecation is that the plane will take off on the treadmill but that must be a pretty long tread mill as the plane still needs a long ways to accelerate to a certain airspeed. If the treadmill doesn't keep it stationary then the treadmill needs to be as long as the runway to say the airplane would "take off on the treadmill"...otherwise it would run off the end of it getting up to the sufficient air speed.

I was in the "Can't Take Off" camp until someone explained it to me.

The airplane is not dependent on "wheel speed" to take off. If the aircraft needs to travel (using round, theoretical numbers) 100' to achieve a 50 mph takeoff speed, then any thrust produced needs to move that aircraft the 100' to achieve the 50 mph.

The WHEEL speed might be 100 mph to account for (notice, not OVERCOME) the runway/treadmill reverse direction, but the aircraft isn't dependent upon wheel-speed to achieve takeoff.

Using your example, if one could build a constant-moving treadmill of gigantic proportions, and run it against the direction of the aircraft, the thrust of the engines would still accelerate the plane's airframe (though the wheels would be spinning at an ever greater speed) until the plane reached the needed takeoff velocity/distance.

Unlike a car, bus, truck or train that are dependent on wheels being driven to achieve distance/motion (or a boat in a flowing river). THEN, one could move the treadmill in the opposite direction at the indicated speed and the vehicle would remain stationary.

It seems that Mythbusters proved that point. This is not the same as an experiment where the plane was being drug backwards at 300 mph and then had to overcome that inertia, but rather an experiment to see if matching the ground speed with the needed airspeed would prevent the aircraft from achieving lift velocity. Nope! The airplane still moved ahead with the wheels spinning madly.

_____________________________________________________________________

And...enough with the name calling and pseudo bitch-slapping. Its sophomoric at best and at least insulting and unnecessary. So you were right...you've likely been wrong somewhere and/or sometime. These are friends and riding pals, not targets. If they can't get their mind wrapped around a concept that YOU haven't been able to explain to the satisfaction of their inquisitive nature, whose fault is that?

 

[Scab]

Sheesh.

First, I want a list of all people that think the plane cannot take off.

Second, I want to know where you went to school.

Third, I send my kids to a different one.



A famous line from a movie comes to mind:

"Run, Forrest, Run!"

 

[odot]

The "myth" should be changed to "Can a conveyor belt keep an airplane stationary?". That is the "real question". And the answer is no.

FUZZY GERBILSSSSSSSS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[madmike2]

Second, I want to know where you went to school.

Eye wint tuh a liddle kuntry skool in Santa Rosa, CA. We'uns had 'bout 30 kiyids en wun teecher. Thet en t'was Furst alla thuh weigh tun Sickst grayd en thuh saym rume. We din't noe nuthin' from noe hairplayns en sientifical stuff, we wuz allays werkin' onta grammer, reedin' en rithymetick. We'uns gots purdy gude, tew. Mosta us kud kount tuh twenny with leevin ar shews onta ar feets.

 

[Capt. Bob]

Sheesh.
First, I want a list of all people that think the plane cannot take off.

You'll find that on the forum where the member is gathering data on breaking in his bike. :blink:

 

[wfooshee]

I saw something like this to explain it on another forum:

Say you have one of those lightweight gliders that's launched by a truck and tow line. Put the glider (but not the truck) on the conveyor. Drive the truck. The conveyor will not, can not impede the forward progress of the aircraft. The truck will pull it to launch speed.

You may say, "Well, yeah, the truck isn't affected by the conveyor! It's completely separate!"

DING DING DING DING DING DING DING DING DING DING DING DING DING ! ! ! ! ! ! ! ! ! ! ! ! !

Now give it a rest!

 

[Rogue]

I can't believe all the people who don't get this! I 'm not going to read all the stupidity to see if this has been said,

With an airplane

[SIZE=36pt]GROUND SPEED DOES NOT MATTER! IT IS AIR SPEED![/SIZE]

The conveyor speed has no relation to the aircraft speed! You could run the conveyor at Mach1 and it wouldn't affect the aircraft speed!

 

[odot]

What aboot the sonic boom, though? Wouldn't that lift it in the air for a split sec?

 

[twowheelnut]

No, odot, but a good refried bean and beer fart would certainly cause lift.

 

[sonicspeed]

No, odot, but a good refried bean and beer fart would certainly cause lift.

somebody call for me to be part of an experiment?????

 

[jestal]

I can't believe all the people who don't get this! I 'm not going to read all the stupidity to see if this has been said,
With an airplane

[SIZE=36pt]GROUND SPEED DOES NOT MATTER! IT IS AIR SPEED![/SIZE]

The conveyor speed has no relation to the aircraft speed! You could run the conveyor at Mach1 and it wouldn't affect the aircraft speed!

Absolutely. And to get that air speed a "real" airplane has to travel a fair distance as it takes time to accelerate and time accelerating equals distance. So...yes....if the treadmill is long enough the airplane will certainly take off.

That is why I say the whole question is a matter of semantics and both answers are correct in a fashion. When the question says "treadmill" I don't think most people assume an infinitely long treadmill that is as long as a normal runway. Park an airplane on a reasonable treadmill, power up and start the tread mill and the plane will not take off on the treadmill. It will roll along on the treadmill, roll off the end of the treadmill and then leave the ground 5000 feet down the runway. Did it take off "on the treadmill"??? I guess it depends on how long you might think a reasonable treadmill is. That's what makes it a trick question to me. There is no treadmill long enough for what I consider to be a real airplane to take off on.

Now if you spilled oil on the treadmill the whole thing changes completely.......

 

[Scab]

No, odot, but a good refried bean and beer fart would certainly cause lift.

somebody call for me to be part of an experiment?????

Stick a cork in it for just a second. We're setting up the treadmill.

I can't believe all the people who don't get this! I 'm not going to read all the stupidity to see if this has been said,
With an airplane

[SIZE=36pt]GROUND SPEED DOES NOT MATTER! IT IS AIR SPEED![/SIZE]

The conveyor speed has no relation to the aircraft speed! You could run the conveyor at Mach1 and it wouldn't affect the aircraft speed!

Now if you spilled oil on the treadmill the whole thing changes completely.......

Would that be dino, or synthetic?

 

[sonicspeed]

No, odot, but a good refried bean and beer fart would certainly cause lift.

somebody call for me to be part of an experiment?????

Stick a cork in it for just a second. We're setting up the treadmill.

ummmm sticking a cork in it is the last thing you want to do........a cork can be considered a deadly weapon when shot out at high speed

 

[Scab]

Yeah, it's all fun and games till someone gets an eye put out!

 

[GunMD]

And...enough with the name calling and pseudo bitch-slapping. Its sophomoric at best and at least insulting and unnecessary.

 


I don't even know you anymore.

 




 

 

[Fred W]

AAaaaaiiiiigghhh!!! :crazy:

Stop the conveyor. I wanna get off.

 

[juniorfjr]

I give, what does odot do with the gerbil?

 

[madmike2]

And...enough with the name calling and pseudo bitch-slapping. Its sophomoric at best and at least insulting and unnecessary.

I don't even know you anymore.

B-b-b--but Scott, I was just trying to live up to (down to???) one of your signature lines:

"Tact is for people who aren't witty enough to be sarcastic"

 

[Scab]

if one could build a constant-moving treadmill of gigantic proportions, and run it against the direction of the aircraft, the thrust of the engines would still accelerate the plane's airframe (though the wheels would be spinning at an ever greater speed) until the plane reached the needed takeoff velocity/distance.

Hey, that's the Earth.

 

[Rondo777]

I can't believe all the people who don't get this! I 'm not going to read all the stupidity to see if this has been said,
With an airplane

[SIZE=36pt]GROUND SPEED DOES NOT MATTER! IT IS AIR SPEED![/SIZE]

The conveyor speed has no relation to the aircraft speed! You could run the conveyor at Mach1 and it wouldn't affect the aircraft speed!

I agree, I cant believe all the people who dont get this too, your one of them

In order to have airspeed the plane has to be moving forward. Do you honestly think that if the plane was just parked on a tread mill and the tread mill was turned on that the plane would just stay stationary? Of course not, it would just move backwards at the same speed as the tread mill. Now fire up the plane, and give it some throttle, it will continue to move backwards along the tread mill until at some point you've put in enough power to just stand still. Now you have a ground speed(realative to the treadmill) but you have zero airspeed. Of course if you add more power to the plane at this point it will start to move forward and gain airspeed but then what happens if you increase the tread mill speed some more? The thing is that you can increase your ground speed realative to the treadmill till your going Mach1 but your airspeed will still be zero and you arnt flying. There is no magic point that the plane which is still on the ground becomes disassociated with the ground. They should have looked at the rpms required to achieve the 25mph air speed needed for takeoff from the runway and kept that a constant for the tread mill take off. The plane would have stood still on the treadmill. All they did was apply enough thrust to the plane to more then compensate for the speed Jamie was pulling the tarp at. I fly RC and actuall have a GWS plane very similar to the one they used on the show. I'm to the point that I'm going to video my plane, on a tread mill, staying stationary. The last thing that I thought was really srewed up was why they didnt just let Grant fly the model plane on the belt. That plane, at full throttle flys almost 50mph, they said that it can fly at 11mph so thats what they set the tread mill speed at. They never said that they limited the throttle on the modle to only 11mph. So if numbnuts Jamie gunned the throttle on the plane then it would def do just what it did and shoot right off the end of the tread mill.