So...about that plane on the treadmill...

wrote in message
ups.com...

Rip wrote:
Yes, the airplane will take off. The thrust of the engine is against the
AIR. NOT the treadmill.

The thrust of the engine is not against the air. It generates
thrust as a Newtonian reaction to the prop moving air back, not
"pushing on other air." A rocket in space has nothing to push against,
yet it generates the same thrust as it did in the atmosphere.

1) Will an airplane on an essentially frictionless surface (say, wet
ice) take off?

Of course, as forward motion creates airflow over the wings.
There is no forward motion on the treadmill.

2) Will a sea plane take off upriver in a current equal to it's take-off
speed (this one is a cheat, since it involves drag not involved in the
original situation, but should be a good "fire starter" for further
discussion).

Yes, it would, but it's waterspeed at takeoff airspeed would
be double the usual takeoff speed. However, this would require
considerable power to overcome the extra drag of the floats on the
water, being a lot more than wheels on pavement.

I have a hard time believing that so many people can't see that it's
airflow over wings, not wheel speed or prop blast, that lifts
airplanes. What do they think wings are for, anyway?

Why don't we discuss something truly valid, like the downwind
turn feared by some (especially a few RC modelers) that they think will
reduce airspeed and cause a stall?

Dan

And, after we've resolved that one, we can move on to the turn to the final
turn for a left crosswind landing from a tight left pattern or a right
crosswind landing from a tight right pattern.

Peter