Re: What's wrong with this picture?

From: Pat Flannery (flanner_at_daktel.com)
Date: 08/30/04 

Date: Mon, 30 Aug 2004 16:42:19 -0500

Henry Spencer wrote:

>In article <10j69mqt6ebar11@corp.supernews.com>,
>Pat Flannery <flanner@daktel.com> wrote:
>
>
>>On the other hand, this ship seems to be _way_ overpowered for something
>>designed to land in 1/6th G: http://www.skiesare.demon.co.uk/l3.jpg
>>
>>
>
>Bear in mind, that's a *big* vehicle and those are undoubtedly quite
>low-pressure engines.
>
Yeah, but even given that, the thing looks like it could land and
liftoff from Earth rather than just the Moon!
Assuming those are the von Braun standard ferry rocket motors on its
back end, it's generating :
55,000 lbs. thrust x 30 motors = 1,650,000 lbs. thrust.(
http://vesuvius.jsc.nasa.gov/er/seh/lunarlan.html ) (Miller gives the
thrust as 940,000 lbs in "The Dream Machines".)
Considering that according to this:
http://www.skiesare.demon.co.uk/cb.html the ship's weight is supposed to
be a total of
8,740,000 lbs on leaving the space station for the moon, then the motor
thrust makes sense, but it has jettisoned its TLI propellant tanks by
the time it arrives at the Moon, and is getting steadily lighter as it
descends due to propellant usage:
http://www.skiesare.demon.co.uk/l1.jpg. shows that a good third or more
of its mass would have been in the jettisoned tanks and their contents,
plus whatever was used during the braking maneuver as it approached the
Moon's surface http://www.skiesare.demon.co.uk/l2.jpg
...and it still looks way overpowered at this point, even given the fact
that the LM had amore efficient hypergolic motor on it.

Pat

Relevant Pages

  • Re: Whats wrong with this picture?
    ... liftoff from Earth rather than just the Moon! ... but it has jettisoned its TLI propellant tanks by ... of its mass would have been in the jettisoned tanks and their contents, ... that the LM had amore efficient hypergolic motor on it. ...
    (sci.space.history)
  • Re: Whats wrong with this picture?
    ... liftoff from Earth rather than just the Moon! ... but it has jettisoned its TLI propellant tanks by ... of its mass would have been in the jettisoned tanks and their contents, ... that the LM had amore efficient hypergolic motor on it. ...
    (sci.space.policy)