Debate!

[RitterKreuz]

if everything was mathematically scaled down correctly - YES - the theory could be proven or dis-proven by use of RC aircraft.

Ask yourself this

if the conveyor belt was turning at 1 knot could the airplane takeoff ?

Yes IAS would still have to be around 150kts while WHEEL SPEED would be around 151kts

if the conveyor belt was turning at 10 knots could the airplane takeoff?

yes IAS would still have to be around 150 knots while WHEEL speed would be around 160 knots

if the conveyor beld was turning at 100 knots could the airplane takeoff?

Yes IAS would still have to be around 150 knots while WHEEL speed would have to be around 250 knots

see the pattern here.

I can lift off an aircraft with ZERO WHEEL SPEED assuming the wind is strong enough so WHEEL SPEED is completely irrelevant to the discussion... in real life wheel speed would only be an issue when it comes to required length of the treadmill and wheel speed limitations... i dont care if the treadmill is going 1,000 knots... assuming that wheel endurance was not an issue the airplane would eventually lift off and when it did lift off it would only be going around 150 knots through the air - given the tread mill would have to be many many miles long!

taking off on a treadmill would have about the same takeoff performance effect on an aircraft taking off in a strong tailwind - it would still achieve lift and fly off but the distance required will be greater.

http://www.straightdope.com/columns/060203.html

[Chris_F]

if everything was mathematically scaled down correctly - YES - the theory could be proven or dis-proven by use of RC aircraft.

Ask yourself this

if the conveyor belt was turning at 1 knot could the airplane takeoff ?

Yes IAS would still have to be around 150kts while WHEEL SPEED would be around 151kts

if the conveyor belt was turning at 10 knots could the airplane takeoff?

yes IAS would still have to be around 150 knots while WHEEL speed would be around 160 knots

if the conveyor beld was turning at 100 knots could the airplane takeoff?

Yes IAS would still have to be around 150 knots while WHEEL speed would have to be around 250 knots

see the pattern here.

You are assuming that the airplane is able to gain airspeed at all.  One could also make the assumption that the friction in the wheel/tire system is great enough that, at some wheelspeed, it is able to entirely counteract thrust and the airplane never gains any airspeed at all.  Like I said, the ability to answer the question lies entirely in what assumptions are made about the system.

Obviously in a real aircaft there is friction in the wheel/tire combo but it is small.  It may be hard to visualize enough friction to entirely counteract the huge thrust from a 747, so imagine upping that friction a bit, perhaps by applying the brakes.  Now do the mental experiement.  Is there a conveyor speed at which the 747 can't gain airspeed now?  Well, the non-brake applied friction has this same effect, albeit for extremely high wheel speeds.

Here's a crazy one in the opposite vein: remember the super-lube used on the big block above?  The one that made things frictionless?  Apply that to the tires and wheel bearings of a 747 on a normal runway.  The airplane takes off... what is the wheel speed?

Zero.