Re: Jet engine 1st stage

On Mon, 19 Sep 2005 16:25:28 -0400, "Jeff Findley"
<jeff.findley@xxxxxxxxxxxxxx> wrote:
><dbohara@xxxxxxxxxxxxxx> wrote in message
>news:1127135506.835715.74830@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> I am sure this topic has been covered here at some time but I missed
>> it.
>>
>> Would it be feasible to use air breathing jet engines as the 1st stage
>> (or as strap-ons) of a launch system? Of course, that is exactly what
>> White Knight is but what about on a larger scale unmanned? This would
>> mean you do not have to lift the oxidizer for the 1st stage but max
>> altitude is limited. Re-use would be a problem if you drop em in the
>> ocean.
>
>There was quite a detailed discussion of this many years ago. Back then, I
>remember it being called "pogo". If you do a Google Groups search for "pogo
>jet engine first stage", you'll find news articles about this concept.
>
>The above led me to here:
>
>POGO (a.k.a. Jet Engine Launch Assist Concept (JELAC))
>http://www.alt-accel.com/pogo/pogo.htm

Short version:

It might help slightly, but the added drag quickly eats up the
advantage of not carrying oxidizer as speed increases in a vertical
launch. In addition, modern jet engines are not designed to be at
their best under these circumstances. You'd probably be better off
with a big crude 1950's style engine than a modern turbofan. In
addition, jet engines aren't disposable on the scale of minutes of
operation, and it would probably cost too much to make it practical.

Regards,
Jack Tingle
.