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CreateThruster: maxth0 in [N] Issue Tools
issueid=941 04-15-2012 08:57 PM
Addon Developer
CreateThruster: maxth0 in [N]
Orbiter API Reference Manual

The Orbiter API Reference Manual says:
maxth0 max. vacuum thrust rating [N]

but it looks like it is in [kN] instead.
I entered the maxthrust in [N] = 1000 x [kN] and it was a pretty impressive launch
Issue Details
Issue Type Feedback
Project ORBITER: 2010-P1 and newer
Status Closed
Priority 10 - Lowest
Regarding Version 101016
Regarding Version (none)
Users who agree 0
Users who disagree 2
Assigned Users (none)
Tags (none)

04-16-2012 07:59 AM
I am pretty sure, that the unit for maxth0 really is [N]ewton!
If you look at several source files (Atlantis SSMEs, Shuttle-OMS, SRBs, AMSO, etc. pp.) you might agree with that
So I don't think there's anything wrong on the API side.
04-20-2012 05:12 PM
Addon Developer
Sorry, may bad!

I took the figures from Astronautix.com and mixed up the comma separator . with the thousands separator ,
You know, it's the other way round on the old continent ...

Must be the reason, why in aviation language they use the word 'decimal' to indicate this separator.
04-22-2012 06:20 PM
Note that the function seems to use the effective exhaust velocity instead of the ISP (although it is named "ISP" in the API).
12-04-2012 05:15 PM
Orbiter Founder
Originally Posted by whitewatcher
 Note that the function seems to use the effective exhaust velocity instead of the ISP (although it is named "ISP" in the API).
Thread closed due to non-issue of original report.

Regarding Isp: both notations are used, as far as I know. Personally, the habit of specifying Isp in units of seconds doesn't make much sense to me. Fuel-specific impulse is defined as the force per unit propellant mass flow per second, so the dimension is that of a speed, isn't it? The only way to get a dimension of time is if you specify the propellant via its weight at some particular location, e.g. on earth at sea level, but that seems completely arbitrary.

I'm afraid orbiter is written by a physicist, not an engineer, so effective exhaust velocity it is.

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