Launching off a planet requires thrust, not ISP (was Resources ainherent)

--- In spacesettlers@yahoogroups.com, Al Globus wrote:
> On Mar 21, 2012, at 3:35 AM, hitssquad wrote:
> > --- In spacesettlers@yahoogroups.com, sraj wrote:
> > > All rocket systems must use only Oxygen and Hydrogen.
> > Hydrogen is a poor fuel to launch with. It gives little thrust, because of its low density.
> Hydrogen/Oxygen rockets have the best ISP

Exactly. Launching off a planet requires thrust, not ISP. Besides, that's vacuum ISP. The first stage isn't in a vacuum, hurting ISP, and also making it difficult to pump low-mass fuels into the combustion chamber.

> You can do a little better with Hydrogen/Flourine or Ozone

You can do massively better with kerosene, which is why the first stage of the Saturn V ran on kerosene. See:
http://www.dunnspace.com/leo_on_the_cheap.htm

Have you read that yet?

Also see all the yarchive discussions on this, and the columns by Arthur Schnitt on this:
http://www.dunnspace.com/home.html