Hiya Tony,
You are right..in building sofware we have that all the time!.."But that is not what I meant!" the customer says.. "But that is what you said!" we say.. ;-)
Sorry, that was my point....blow up and crash or lift off and fly!
edit:
I think it's only reasonable to assume these two scenarios as the rest just make a mockery of language and comunication....there have to be some things that are granted!
edit:
I think it's only reasonable to assume these two scenarios as the rest just make a mockery of language and comunication....there have to be some things that are granted!
Yes..I think you were right on the money!!! Trying to find the answers without first asking some questions about the question is not good..and most of us did just that!
Again it all comes down to the devil being in the details (and the assumptions). I, like many others, assumed that it was the surface speed of the wheel that was supposed to exactly oppose the surface speed of the belt according to the original question.
So did I, but we made different conclusions I think? Even if that is true...the plane will take off. Because it does not counteract the thrust of the motors.
Bas Horneman said:
ahhh I can go to sleep now, I'm not going insane 😉 Thanks Bas.
and yeah I know what you mean about users saying "that's not what I meant" !!!
edit: actually maxro got my drift before too so I'm doubly happy, even if I started out with some very dodgy not based in reality asertions in my very first post 😉 jeezzz what was I thinking 🙄
Tony.
As some of the rest of you are going to bed, I am getting up after having thought this question for the good part of the last two hours.
My conclusion from a few pages ago is ever so slightly flawed.
I said the plane would take off, the wheel and belt speed will be the same as the takeoff speed. I now change it to:
The plane will take off.
The wheel and belt speed are exactly 2X the planes air speed.
This is what pinkmouse said about 15 or 20 pages ago. To paraphrase: "Plane takes off, wheels spin twice as fast, what the big deal?"
pinkmouse if you are still in that boat, save a seat for me. To those who still think the plane will remain stationary, I wonder the the mental block is in understanding the how and the why behind the plane moving?
EDIT: I realize that last sentence is hardly fair as I took the same position about the plane remaining stationary at first also.
My conclusion from a few pages ago is ever so slightly flawed.
I said the plane would take off, the wheel and belt speed will be the same as the takeoff speed. I now change it to:
The plane will take off.
The wheel and belt speed are exactly 2X the planes air speed.
This is what pinkmouse said about 15 or 20 pages ago. To paraphrase: "Plane takes off, wheels spin twice as fast, what the big deal?"
pinkmouse if you are still in that boat, save a seat for me. To those who still think the plane will remain stationary, I wonder the the mental block is in understanding the how and the why behind the plane moving?
EDIT: I realize that last sentence is hardly fair as I took the same position about the plane remaining stationary at first also.
Here's his post.
About as simple as it gets.
http://www.diyaudio.com/forums/showthread.php?postid=775380#post775380
About as simple as it gets.
http://www.diyaudio.com/forums/showthread.php?postid=775380#post775380
Yeh, I know what you mean but it's more than 2x if you relate it to the rotational speed.
The conveyor would have to do one revolution for every revolution of the wheels so the speed would start at damn fast and becuse there would be an oposing reaction from the plane wheels it would increase rapidly to infinity....BANG!
The conveyor would have to do one revolution for every revolution of the wheels so the speed would start at damn fast and becuse there would be an oposing reaction from the plane wheels it would increase rapidly to infinity....BANG!
You can only really see how the question was originally intended and that is the surface speed of the tyre is matched by the surface speed of the conveyor...in this case there is no problem...I dont think??????
EDIT:
The only way that it can cause acceleration of the wheel speed is to disregard the word 'mached' and that would be against the rules. It has been said previously that this scenario is impossible and you have to agree, how do you match the speed without acting upon the wheel....pretty difficult...
EDIT:
The only way that it can cause acceleration of the wheel speed is to disregard the word 'mached' and that would be against the rules. It has been said previously that this scenario is impossible and you have to agree, how do you match the speed without acting upon the wheel....pretty difficult...
Bas Horneman said:
Add the speed of the plane through the air necessary for takeoff to the equal and opposite speed of the reactionary belt.
Belt and wheel speed = 2X the air speed.
I'm almost sorry for posting the question...
Almost 😀
Another way to look at it would be...
At what speed would a conveyer belt need to move in the same direction of a freely turning wheel in order to match the speed of the tyre in order to keep the wheel from rotating about the axel when the wheel is pushed at 10 MPH by the axel.
Easy peasy. 10 MPH - the axel is still doing 10 MPH relative to a fixed point on the ground but the wheel doesn't turn at all.
Now reverse the belt, the wheel is still being pushed along by the axel at 10 MPH but the tyre is now turning at 20 MPH because of the 10 MPH from the pushing and the 10 MPH of the belt - the belt is matching the speed of the wheel but in the opposite direction.
The only additional force on the axel is from the frictional inefficiency of the bearings.
If the plane was kept on the ground by the conveyor I.E. it remained stationary relative to a fixed point on the ground, it would be impossible to pull someone on rollerskates at 3 mph along a travellator doing 3 MPH in the opposite direction.
That's my interpretation anyway FWIW. 🙂
Or....
Is it possible for a conveyor belt to prevent a freely turning wheel attached to an axel from being pushed along by the axel even if the conveyer belt is free to run at any speed within reason?
Almost 😀
Another way to look at it would be...
At what speed would a conveyer belt need to move in the same direction of a freely turning wheel in order to match the speed of the tyre in order to keep the wheel from rotating about the axel when the wheel is pushed at 10 MPH by the axel.
Easy peasy. 10 MPH - the axel is still doing 10 MPH relative to a fixed point on the ground but the wheel doesn't turn at all.
Now reverse the belt, the wheel is still being pushed along by the axel at 10 MPH but the tyre is now turning at 20 MPH because of the 10 MPH from the pushing and the 10 MPH of the belt - the belt is matching the speed of the wheel but in the opposite direction.
The only additional force on the axel is from the frictional inefficiency of the bearings.
If the plane was kept on the ground by the conveyor I.E. it remained stationary relative to a fixed point on the ground, it would be impossible to pull someone on rollerskates at 3 mph along a travellator doing 3 MPH in the opposite direction.
That's my interpretation anyway FWIW. 🙂
Or....
Is it possible for a conveyor belt to prevent a freely turning wheel attached to an axel from being pushed along by the axel even if the conveyer belt is free to run at any speed within reason?
Yeah I know 🙂
The wheels would just spin faster and faster as the velocity of the axels (or plane attached to them) increased.
The above is just for illustration not as a complete explanation of the model.
(BTW - please don't ban me 😀)
The wheels would just spin faster and faster as the velocity of the axels (or plane attached to them) increased.
The above is just for illustration not as a complete explanation of the model.
(BTW - please don't ban me 😀)
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