Question: Can a conventional powered airplane take off from a conveyor
belt which is moving at the same speed but in an opposite direction?

I was surprised at people's range and passion of answers when I asked
this of my glider club. * People were absolutely sure it wouldn't work
or it would work. *I guess that goes to show that performing this as a
thought experiment is not easy even for pilots.

Please make your own guess before you watch these Youtube videos (in
order) for the final answer.

http://youtube.com/watch?v=KSBFQOfas60* Start
http://youtube.com/watch?v=S377HwOthjo
http://youtube.com/watch?v=0ul_5DtMLhc Finish

What I am really surprise about is that the "test" pilot in this video
of the airplane had the wrong answer before his attempt and was very
surprised afterwards. *Well, maybe not surprised, he was a light sport
pilot after all. *Personally, I knew the correct answer from the get-
go. *Hint: The answer is in the wheels.

- John

Relativity!!

The misunderstanding probably derives from the fact that the question
is inadequate in not specifying whether the plane is to be regarded as
moving as the same speed (but opposite direction) as the conveyor
relative to the belt or relative to the ground/nil wind airmass. The
motor vehicles in the videos are moving oppositely at the same speed
relative to the belt - i.e. stationary relative to the ground/
airmass. The propeller aeroplane is moving oppositely relative to the
ground/airmass and so obviously should have no great difficulty in
taking off - it is, however, at take off, moving at about twice the
speed relative to the belt as the belt is relative to the ground. The
fact that the freewheel/propeller derived thrust characteristics of an
aeroplane allow it to achieve take does not negate the fact that at a
lower power setting it could be set up such that it remained
stationary relative to the ground (like the cars) in which case it
would not take off - and this is what many people would probably
assume was meant by the question.

The question not logically valid as it implies two possible but
different hypotheses.

John Galloway