Orbiter-Forum  

Go Back   Orbiter-Forum > Far Side of the Moon > Backyard Rocketry
Register Blogs Orbinauts List Social Groups FAQ Projects Mark Forums Read

Backyard Rocketry Model, Amatuer, Experimental, and High Power Rocketry. Vehicle and Motor/Engine Design, Physics and Math, Fabrication, Flights, Testing and Evaluation. Share your rocket projects here!

Reply
 
Thread Tools
Old 03-28-2019, 11:49 AM   #1
SpaceCrazy5
Orbinaut
Default Specific gas constant; how?

I've been researching a lot about rocketry, specifically rocket engines. I decided to give designing one a go, but I'm slightly stuck; how am I supposed to calculate the Specific Gas Constant of the combustion chamber gas?

It's mostly confusion to do with the molecular mass, and how that relates in terms of the oxidizer/fuel ratio, and other factors.

Sorry if I've posted this in the wrong place, I'm just confused!
SpaceCrazy5 is offline   Reply With Quote
Old 03-28-2019, 11:20 PM   #2
Thunder Chicken
Fine Threads since 2008
 
Thunder Chicken's Avatar
Default

Well, first thing to know is that the combustion gases are not ideal gases, so use of a gas constant and constant specific heats is a gross simplification. It can be used as a crude and simple approximation, but I wouldn't expect anything more from it.
Thunder Chicken is offline   Reply With Quote
Thanked by:
Old 03-29-2019, 01:58 AM   #3
Linguofreak
Orbinaut
Default

Quote:
Originally Posted by SpaceCrazy5 View Post
 I've been researching a lot about rocketry, specifically rocket engines. I decided to give designing one a go, but I'm slightly stuck; how am I supposed to calculate the Specific Gas Constant of the combustion chamber gas?

It's mostly confusion to do with the molecular mass, and how that relates in terms of the oxidizer/fuel ratio, and other factors.

Sorry if I've posted this in the wrong place, I'm just confused!
There may be a few people on the forum who can help, but in general this is a fairly deep subject. In general, the specific gas constant depends mostly on the structure of the molecule: all monatomic gasses tend to have about the same specific gas constant, all diatonic gasses share (more or less) a different gas constant, and so forth. The problem in a combustion chamber is that the chemical composition of the gas changes rapidly as the fuel burns.
Linguofreak is offline   Reply With Quote
Reply

  Orbiter-Forum > Far Side of the Moon > Backyard Rocketry


Thread Tools

Posting Rules
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
Forum Jump


All times are GMT. The time now is 06:21 PM.

Quick Links Need Help?


About Us | Rules & Guidelines | TOS Policy | Privacy Policy

Orbiter-Forum is hosted at Orbithangar.com
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Copyright 2007 - 2017, Orbiter-Forum.com. All rights reserved.