On Mon, 15 Oct 2007 08:01:24 -0700, Ian
wrote:

On 15 Oct, 14:19, (Richard Casady) wrote:
On Sun, 14 Oct 2007 23:31:30 -0700, Ian
wrote:

What force do you think does work against gravity to allow aeroplanes
to ascend?

Thrust from the engine, of course.

Nope. How many aircraft do you think are capable of vertical takeoff?

Handwaving. The only possible source for the increase in the
gravitational potential energy is the engines. Wings impart no energy
that is not their function. There is drag that goes with lift, and
engines have to impart energy to overcome it. I have had a commercial
pilots license for more than forty years, if you want more handwaving.

A Boeing 747-400 has a take off weight of 875,000 lbf and a total
thrust of 4 x 63,300 = 253,200 lbf.

My own aircraft has a take off mass of 370kg and no thrust whatsoever,
and yet I can get it to go up.

Not in still air. You can get it to sink into a mass of rising air.
Or do you have a balloon. Those burners suck fuel like an engine, the
chief concern is having a source of energy same as with an engine.

Casady