160 replies to this topic

[Robin.]

flamineagle, on Dec 4 2005, 05:33 PM, said:

motorman, on Nov 29 2005, 08:51 PM, said:

Beats the crap out of me, but I want the department of defense contract  so I can go out and buy a pilatus pc-12   (a real one).Here is another one if a 747 is full of
doves and the doves are let out of their  cages  does the planes weigth go down?
If a man walks down the asile of a 747 then walks back and hits another person going in the opposite direction is that a 1000 mph collision?
just food for thought
motorman

that last one was pretty good, but it wouldnt be an 1000mph hour collision because presuming he is walking towards the front of the aircraft, the person he bangs into would be going backwards 100mph

It wouldn't be a 1000mph collision. The people are both going at 500mph forward, the man is walking down the aisle at say 1mph, so he's going forward at 499mph, and the other is going up the aisle at 1mph, so he's going at 501mph which equals a 2mph collision

[Flying_Scotsman]

I thought we established that the aircraft would takeoff around about page 2  

[KVNY]

Dr...Watson, on Dec 7 2005, 12:10 PM, said:

I thought we established that the aircraft would takeoff around about page 2  

  

[Satan]

Since  this topic started, that airplane would have took-off and completed 40 long-hauls till now....  

Edited by powerbuddy, 07 December 2005 - 07:29 PM.

[b7e7jon]

Would the friction of the wheels against the canveyor belt slow the A/C down and make it take more space(10 meters or so I guess)? I know it could take off.

[kenair744]

Think of the 747 in a vacuum container...
No air/ nothing...

Is that what you are all talking about?

[Heathrow Tower]

Not another conveyor belt theory. The fact is this: the plane will take off normally because the wheels free-whell.

[Pattyboy10]

Heathrow Tower, on Mar 25 2007, 11:15 AM, said:

Not another conveyor belt theory. The fact is this: the plane will take off normally because the wheels free-whell.

wauw, someone brought the topic back haha

Well he is right though, It WILL take off. don't get mad, I always thought it wouldnt, but the wheels will keep spinning, and the airplane will get forwared, its the thrust if the engines that push the plane, so the wheels have no infuelnce.

[Captainmk]

Did you really have to bump this thread from two years back!

[Pattyboy10]

captainmk, on Mar 25 2007, 02:21 PM, said:

Did you really have to bump this thread from two years back!

haha lol, its always a fun topic!

[spitfir3]

This topic isnt fun

it wouldnt fly, end of.  <--- there ive spoken, now sthu!

[dolbinau]

It's not that fun because everyone agrees it will takeoff now .

A more detailed account of why:

http://www.straightd...mns/060203.html

[89-LX]

In theory, the plane WILL take off. In reality, it will NOT take off.

Pattyboy: The tire DO have an influence on the aircraft. They reduce ground friction, but there is still parasite drag and friction there.

[toast]

Before i say anything...Why are we so complexed about it? Is it really gonna matter in the future? never the less, now?
We could sit here and argue about it, and get no where with life...it is kinda pointless...although extremely fun.

I started out in disagreeing with the plane flying, but after reading replies on this topic, it has changed my view.

I know it's been explained over and over...and over again, but i thought of way to view it also.

Imagine a rope tied to the nose of the plane (whose engine(s) is(are) off), the other side of the rope is tied on to a stake somewhere ahead of the plane.
Now the conveyor belt starts to move, the plane (because it is tied to the ground) will not move, but the wheels will.

Now, as said before, the wheels do not propel the Aircraft, the Thrust from the engine(s) do. So cutting the rope will eventually force the plane off the belt (if there is no engine(s) still).

Now with the rope retied to the plane, and the belt moving again, Imagine starting the engine and throttling up.
The plane will start to move forward from the thrust of the engine(s). Therefore, creating slack in the rope, indicating that the aircraft has indeed moved forward.***

Now for takeoff the aircraft must attain the required lift, which means it must attain a certain AIRspeed on the aircraft.
So the plane will have to provide a lot of thrust.


*** = A small idea popped into my head that if the belt was sped up to match the wheels supposed speed at that amount of thrust, then maybe it wouldn't take off....but I'm not sure about that.

I know a lot of that has been said before...but that's just the way i saw it.
------------
Now about the Man on board a plane who hits another traveling in the opposite direction.

If the aircraft is traveling 250 knots. Every object inside and on that aircraft 250 knots with it.

If a man was to stand out of his seat and walk to the aft of the aircraft,
he would be moving at a very slightly slower speed than the aircraft.

If the man moved to the front of the aircraft,
he would be moving at a very slightly faster speed than the aircraft.

You would add/subtract the amount of speed, by the speed of the walk.

So if Man1 stands up in the front of the aircraft and moves to the aft,
and a Man2 in the aft stands up and moves to the front,
if they were to collide with each other,
Man1 would be going say, 248 Knots
Man2 would be going say, 252 knots

They would collide at those speeds with each other,
therefore, it would be a 500 knot collision.

*The speed difference between the plane and the men walking in the plane is exaggerated for imagery.*

The second one is possibly wrong, correct me if it is.

Thanks,

-T

[Vlad]

toast, on Mar 25 2007, 08:19 PM, said:

Now about the Man on board a plane who hits another traveling in the opposite direction.

If the aircraft is traveling 250 knots. Every object inside and on that aircraft 250 knots with it.

If a man was to stand out of his seat and walk to the aft of the aircraft,
he would be moving at a very slightly slower speed than the aircraft.

If the man moved to the front of the aircraft,
he would be moving at a very slightly faster speed than the aircraft.

You would add/subtract the amount of speed, by the speed of the walk.

So if Man1 stands up in the front of the aircraft and moves to the aft,
and a Man2 in the aft stands up and moves to the front,
if they were to collide with each other,
Man1 would be going say, 248 Knots
Man2 would be going say, 252 knots

They would collide at those speeds with each other,
therefore, it would be a 500 knot collision.

*The speed difference between the plane and the men walking in the plane is exaggerated for imagery.*

The second one is possibly wrong, correct me if it is.

Thanks,

-T

Wow, you need to learn about Vectors, and fast!

The speed of the collision would be 252-248=4 Knots...

[rabbitweasel]

I can't believe someone brought this topic back up. There's a youtube video that was posted once, but I can't find it proving the aircraft will take off. Friction will eventually win over if it was moving fast enough but the only thing that would result from having a conveyer belt moving in the opposite direction is the wheels traveling a distance twice the velocity of the aircraft. The straightdope does a good job of explaining it.

[reyven]

just get Myth Busters to put this theory to rest

[kenair744]

What if the plane is in a vacuum????

Corsair1138, on Nov 29 2005, 02:08 PM, said:

On a day with absolutely calm wind, a plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. The conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

Can the airplane ever take off?

One question- Engines ON or OFF????

Someone put in a request to Mythbusters and see if they CAN do this experiement???

[KVNY]

kenair744, on Mar 25 2007, 07:55 PM, said:

What if the plane is in a vacuum????

Corsair1138, on Nov 29 2005, 02:08 PM, said:

On a day with absolutely calm wind, a plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. The conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

Can the airplane ever take off?

One question- Engines ON or OFF????

Someone put in a request to Mythbusters and see if they CAN do this experiement???

a vaccum? where did that come from?  If theres no air the engine cant run... no oxygen, no combustion.  And if you got the plane up to t/o speed it wouldn't t/o either cause there no air for the wings to create lift...  Not to mention the pilot would be dead   .. unless he's wearing a pressure suit or somthing...  

Edited by KVNY, 26 March 2007 - 12:15 AM.

[Fokker_F27]

Yes, it can! Some aircraft, like the Piper J3 Cub can generate enough wind with their engine to take off in barely their length, if the parking break is set. And of course, the Boeing V-22 Tiltrotor can take off without a rwy easily.

Edited by Fokker_F27, 26 March 2007 - 04:52 AM.