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

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

On Tue, 16 Oct 2007 01:13:56 -0700, Ian
wrote:

How do you think helium balloons work?

You have me there. However, how many do you think are in use? I would
guess somewhere between zero and none. For all practical purposes they
don't exist.

Myself, I like to fly small hydrogen balloons. Dry cleaner bags. You
dissolve aluminum chips in lye to get the hydrogen.

Casady

On 16 Oct, 14:32, (Richard Casady) wrote:
On Tue, 16 Oct 2007 01:13:56 -0700, Ian
wrote:

How do you think helium balloons work?

You have me there. However, how many do you think are in use? I would
guess somewhere between zero and none. For all practical purposes they
don't exist.

Doesn't mean they don't work.

Ian