On 16 Oct, 00:11, (Richard Casady) wrote:
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.

The question was not "where does the energy come from?". The question
was "what force ... does work against gravity ...?" and (save for a
trivially small downwards component) that ain't thrust.

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.

A glider can climb in still air. Not for very long, normally, but it
can certainly climb. No thrust.

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.

How do you think helium balloons work?

Ian