A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Technology
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Have I got my figures correct?



 
 
Thread Tools Display Modes
  #1  
Old November 19th 10, 01:29 PM posted to sci.space.tech
Damon Hill[_4_]
external usenet poster
 
Posts: 566
Default Have I got my figures correct?

Christopher wrote in
:

Could one of you please check my figures in the below work I have been
doing. As I have a feeling my calculations are maybe way short on
reflection, as I have used web based conversion utilities, as I never
did physics at schoool as physics was never on the schools syllabus.


Several thoughts: don't use nuclear thermal except for the final stage;
the high Isp is not particularly useful for climbing out of the bottom
of a gravity well. High thrust is; use kero/LOX as it's FAR more
cost-effective.

A 1.5 million lb/thrust NTR means something on the order of a terawatt
nuclear reactor. Think about this in practical terms. If you are only
going to low orbit, there's no need for NTR at all. Attempting to
design a three-stage NTR for low orbit is absurd in too many ways
to summarize here.

"Fuel" in a nuclear thermal rocket is the uranium/plutonium which
provides the heat to expand a "reaction mass", typically liquid
hydrogen. Ammonia could be used if higher thrust is desired; it has a
slightly higher mass and much better density, is only a mild cryogen,
and should decompose into nitrogen and hydrogen to yield a better Isp.
Methane seems practically useless in a NTR and only marginally useful
in a chemical rocket.

Simplicity is a high virtue in rocketry; the more parts the higher
the cost and failure rate. Your design philosophy is hopelessly and
unnecessarily complex, and reflects a very poor understanding of
rocket engineering.

Get thee hence to "Rocket Propulsion Elements" by Bruce Sutton or
similar books (check on Amazon for used copies) and start learning.

--Damon

  #2  
Old November 22nd 10, 06:22 PM posted to sci.space.tech
Christopher[_5_]
external usenet poster
 
Posts: 8
Default Have I got my figures correct?

On Nov 19, 12:29 pm, Damon Hill wrote:
Christopher wrote innews:ec783d1a-5c21-48a

:

Could one of you please check my figures in the below work I have been
doing. As I have a feeling my calculations are maybe way short on
reflection, as I have used web based conversion utilities, as I never
did physics at schoool as physics was never on the schools syllabus.


Several thoughts: don't use nuclear thermal except for the final stage;
the high Isp is not particularly useful for climbing out of the bottom
of a gravity well. High thrust is; use kero/LOX as it's FAR more
cost-effective.

A 1.5 million lb/thrust NTR means something on the order of a terawatt
nuclear reactor. Think about this in practical terms. If you are on

ly
going to low orbit, there's no need for NTR at all. Attempting to
design a three-stage NTR for low orbit is absurd in too many ways
to summarize here.

"Fuel" in a nuclear thermal rocket is the uranium/plutonium which
provides the heat to expand a "reaction mass", typically liquid
hydrogen. Ammonia could be used if higher thrust is desired; it has a
slightly higher mass and much better density, is only a mild cryogen,
and should decompose into nitrogen and hydrogen to yield a better Isp.
Methane seems practically useless in a NTR and only marginally useful
in a chemical rocket.

Simplicity is a high virtue in rocketry; the more parts the higher
the cost and failure rate. Your design philosophy is hopelessly and
unnecessarily complex, and reflects a very poor understanding of
rocket engineering.

Get thee hence to "Rocket Propulsion Elements" by Bruce Sutton or
similar books (check on Amazon for used copies) and start learning.

--Damon


Thank you for the clarifiacations and the warning signs. Appreciated.

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
S-IVB staging figures Jud McCranie[_2_] History 2 July 17th 09 08:50 PM
NASA facts and figures needed Jim Oberg History 2 October 26th 05 04:56 AM
Cowing's budget figures? Jim Gergen Policy 2 January 16th 04 05:45 AM
"Liars Figure, but Figures Don't Lie" John Maxson Space Shuttle 6 September 23rd 03 01:12 PM
Is a Correct Image Finder Really Correct? Alan French Amateur Astronomy 0 August 1st 03 04:10 AM


All times are GMT +1. The time now is 06:11 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.