Aircraft and conveyor belt (again)

[megawatt]

What's the point trying to keep this going when there's no substance to it any more ... Lock it mods ... DO IT NOW

 

[tim west]

No mods dont listen theres at least another 5 pages worth of important discussion in order to get a definitive answer to this perplexing problem

 

[bernardgreen]

PLEASE nice MODS. please don't end this thread and leave the discussion in mid air. ( or is it mid conveyor )

 

[Softus]

What do we want? IT LOCKED!

When do we want it? NOW!

 

[tim west]

At this point i'm going to do a joe and say that as no one has questioned my previous reply that i must have been correct in my assumptions and everyone else was therefore wrong.

Unless of course you know better and want to reply?(he won't)

 

[Nige F]

he will

 

[tim west]

 

[tim west]

I wonder if the thread will reach its goal if we add the fact that the pilot is an off duty NHS doctor?

 

[tim west]

It was supposed to be in humour but i suppose in that context it could have been construed as offensive, apologies mod.

 

[megawatt]

Whatever it was ... Naughty naughty

 

[blondini]

As a member of the yes it will take off club, I thought it was an interesting video.
But it did not, and could not perform the experiment as described in the original question.

What was very salient however, were the pilots words "we took off as normal". IE. their was no drag backwards, and no extra power was needed to take off.

Which proves that the wheel speed was irrelevant, Newtons third law of motion moves the plane forward, irrespective of what the wheels are doing.

So I believe you can now choose from 2 scenarios.

1) In a real life experiment, its just whether you think the wheels could survive the speeds generated.

2) In a purely theoretical argument, let the wheels do an infinite speed , the plane will still take off.

And johnD ,where I think your argument fails, about the impossibility of the question, is that you are considering a plane doing 1 mph and trying to hold station at 1 mph, and yes the wheel speed would build up very quickly.
Whereas in reality we are considering a rapidly accelerating plane where the conveyor will be playing catchup. The conveyor will have 15 to 20 seconds to impart as much speed as it can.

As a member of the no, maybe it won't take off club, I also thought it was an interesting video I agree it did not and could not perform the experiment as described in the original question. (Very well put by the way).

I even agree with Megawatt in his assesment of the pilot, though probably not for the same reasons.

I agree that the guys in the video said it made no difference, but if there had been just a very small difference, would they have noticed, did they try to measure it? No matter. There was evidently no appreciable difference, and as far as their experiment went that was acceptable.

Although it is a hypothetical question, I prefer to consider it as a real life experiment and I don't think the tyres would survive. Disregarding other forces,acting on the tread, the magnitude of centrifugal force pulling at it increases as a the square of the speed. I am not making this up. I found some figures on a Goodyear site. For a 30" diameter tyre, the tread is subject to 500Gs, at 200mph it would be 2000Gs, and at 400mph it would be 8000Gs.

In a purely theoretical argument where you have indestructible tyres etc, Would you also disregard friction and rolling resistance? I'm genuinely interested in what happens if you don't.

 

[tim west]

I used joes favourite word that starts with i and ends in t

 

[tim west]

Taking it from a purely theoretical stance then there should be no lag in the belt catching up, it should be instantaneous otherwise all other "real world" obstacles would also come into play.

 

[megawatt]

This thread is making my teeth itch now.

 

[tim west]

you've only got to scratch em for four more pages