Meadville Space Center

Project Apollo - NASSP => Programming => Topic started by: movieman on April 22, 2008, 01:36:42 PM



Title: Saturn LVDC and TVC issues
Post by: movieman on April 22, 2008, 01:36:42 PM
Would probably also be good to add some kind of more realistic drive rates to the Saturn nozzles so they don't swing around so fast (or so far) during the launch.


Title: Saturn LVDC and TVC issues
Post by: kneecaps on April 22, 2008, 01:48:23 PM
Would probably also be good to add some kind of more realistic drive rates to the Saturn nozzles so they don't swing around so fast (or so far) during the launch.


Excuse my lack of current knowledge on the project, how are the Saturn nozzles currently driven? Is it a canned routine or is approximation of the LVDC doing the driving?


Title: Saturn LVDC and TVC issues
Post by: lassombra on April 22, 2008, 02:29:08 PM
Right now, they just pass the desired value to Orbiter.

What we need to do is damp those values.


Title: Saturn LVDC and TVC issues
Post by: kneecaps on April 22, 2008, 04:06:14 PM
Right now, they just pass the desired value to Orbiter.

What we need to do is damp those values.

Right, so what generates the values in the first place? This is the key, because if the response to the gimbal commands is expected/assumed to be instant it could destroy the launch guidance. The question is it currently open or closed loop. If it's closed loop then that's a better start, if it's flying totally open loop then more will have to be done. I talking about the Saturn here (as the AGC  TVC DAP is clearly closed loop!)



Title: Saturn LVDC and TVC issues
Post by: dseagrav on April 22, 2008, 04:32:10 PM
Saturn gimbal commands are generated by an analog computer attached to the LVDA called the FCC.


Title: Saturn LVDC and TVC issues
Post by: movieman on April 22, 2008, 06:07:47 PM
Saturn gimbal commands are generated by an analog computer attached to the LVDA called the FCC.

Is that actually implemented yet?


Title: Saturn LVDC and TVC issues
Post by: dseagrav on April 22, 2008, 06:26:01 PM
Is that actually implemented yet?

I had most of an implementation in the LVDC++ (I don't think it did travel rate limiting) but I don't think the normal autopilot does it.
VS seems to be crashing my computer for some reason so I can't open it and check.


Title: Re: Saturn LVDC and TVC issues
Post by: Tschachim on April 23, 2008, 04:30:41 AM
I split and put the Saturn stuff in a new topic, I hope this is fine for everybody.

Cheers
Tschachim


Title: Re: Saturn LVDC and TVC issues
Post by: Swatch on May 02, 2008, 02:01:09 PM
does anyone have the gimbleing rates?


Title: Re: Saturn LVDC and TVC issues
Post by: kneecaps on May 02, 2008, 04:56:38 PM
does anyone have the gimbleing rates?

I've read 5 degrees per second on the S-I. I'll try and locate the other stages. Remember the centre engine isn't gimballed!!

EDIT: Come across 9.6 degrees per second for S-II..again centre engine not gimballed.

Can't find anything at the moment on the S-IVb



Title: Re: Saturn LVDC and TVC issues
Post by: Swatch on May 02, 2008, 06:21:15 PM
S-IVB is extremely likely to either be the same as the S-II outer engines  -OR- its fixed because of the existence of the APUs on the side of the stage.


Title: Re: Saturn LVDC and TVC issues
Post by: kneecaps on May 03, 2008, 05:00:52 AM
S-IVB is extremely likely to either be the same as the S-II outer engines  -OR- its fixed because of the existence of the APUs on the side of the stage.

I'm pretty sure it's gimballed! I just don't have any info on the dive rates.

Apparently the S-II engines were limited to 7 degrees of travel in either direction...

And the S-I engines were limited to 5.1 degrees in either direction.


Title: Re: Saturn LVDC and TVC issues
Post by: kneecaps on May 03, 2008, 07:04:54 AM
The AS-503 saturn V report says the maximum S-IC gimbal angle was 2.06 degrees during the flight...so nominal deflection wasn't even half of maximum.