Tuesday, June 9, 2009

Errata - Saturn Fuel Rockets are Liquid Fueled

Update: A different reader wrote in with more information on the Saturn Rocket in the Apollo program.
On page five of your book Absinth and Flamethrowers, you state that solid rocket motors
were used in the Saturn V rocket during the Apollo missions. This is incorrect.

The first stage of the Saturn V (the S-IC) had five F-1 rocket engines. The propellents in these
were liquid oxygen and kerosene. These were the largest liquid rocket engines ever built.

The second stage (the S-II) had five J-2 engines. The propellents in these engines were liquid
oxygen and liquid hydrogen.

The third stage (the S-IVB) had one J-2 engine, also propelled by liquid oxygen and liquid hydrogen.

The propellents in the Apollo Service Module were hypergolics, not needing an oxidizer for ignition.
For this nitrogen tetroxide and unsymmetrical dimethylhydrazine were used.

The lunar modular also used hypergolics -- nitrogen tetroxide and Aerozine 50 (a half and half
mixture of unsymmetrical dimethylhydrazine and hydrazine). These were used in both the descent stage
and the ascent stage.

The only place solid propellents were used in the Apollo system were in the launch escape system.
The escape tower sat atop the command module. There were three solid rocket motors attached to the
tower. In the event of a booster malfunction, the solid rocket motors would be used to pull the
command module free of the Saturn V. Thankfully, this was never necessary.

The use of solid rocket motors in manned spaceflight is the source of some controversy since they
cannot be throttled and once activated they cannot be turned off. The worst case scenario played out
in the case of the Challenger disaster when an O-ring failure in a solid rocket booster led to the
explosion. Reportedly, von Braun was opposed to the use of solid rocket boosters in the shuttle
system for just this sort of reason. However, solid rockets are cheaper than liquid rockets, and due
to budget cuts NASA incorporated the solid rockets into the shuttle system.

But solid rocket motors did not boost the Saturn V to the moon.
A reader wrote in an Amazon review that in Absinthe and Flamethrowers, I referred to the engines of the Saturn V rocket as being solid fuel, when in fact, they are liquid fuel. Evidently, this freaked out the reader so much that he one-star rated the book on Amazon, based on this single error.

Sheesh, that seems pretty harsh.