#1
|
|||
|
|||
Problems with stability in RockSim
Hi Folks!
I just downloaded the RockSim file for the Apogee 1/70 Saturn V. When I tried to run a simulation using one of the engines already listed in the simulations tab, the rocket went unstable right off the launch rod. Has anyone else tried to run a simulation of this beast and had the same thing happen to them? I'm sure it is some parameter I haven't set up correctly. Thanks! Roy
__________________
Roy Tuinila CMASS Member NAR #90252 NARTREK Bronze L1 w/Mega Der Red Max on an H87-IM-7 |
#2
|
||||
|
||||
First thing I would check is your wind speed settings. Next maybe rod length.
__________________
Bernard J. Herman Ohio RLS Starport Sagitta Rockets email bherman@sagittarockets.com NAR # 97971 SR What's your idea on the best way to change Washington D.C.? Let us know at the Cantina Sagitta Cantina We're looking for a few good Catos, please tell us about any you may have had. Survey of Anecdotal Malfunctioning Engines or S.A.M.E. |
#3
|
|||
|
|||
Quote:
+1 If you're set up for smaller rockets (Alpha, Big Bertha) your rod may be too thin or too short for an SV. (edit) My better 2/3 laughed hysterically. I'm leaving it.
__________________
Clear skies and fair winds, Mike NAR 31689 |
#4
|
|||
|
|||
Thanks, I've tried setting the wind setting to "no wind" and the launch rod to 72 inches with no effect on the simulation. I even tried Mass Override and set the cg to 8 inches from the nose instead of the original 28.000 inches. Still no joy.
__________________
Roy Tuinila CMASS Member NAR #90252 NARTREK Bronze L1 w/Mega Der Red Max on an H87-IM-7 |
#5
|
|||
|
|||
Quote:
Is this a simulation that had been run before you opened RockSim? If so, what were the results of that sim? Compare the details of that sim with yours. Look for differences. The Apogee .rkt file shows a problem with H120-6 and G80-4 motors. Look at the details on those, also.
__________________
Clear skies and fair winds, Mike NAR 31689 |
#6
|
|||
|
|||
Yes, when I opened the simulations tab I saw the G80-4 engine listed. When I tried to run a simulation with that engine, the rocket went unstable.
__________________
Roy Tuinila CMASS Member NAR #90252 NARTREK Bronze L1 w/Mega Der Red Max on an H87-IM-7 |
#7
|
||||
|
||||
I don't use RockSim, but I imported the RS file into OpenRocket and stuck in a G80-4; the flight profile looked fine. But OR doesn't support pods, which are used in the RS model for the conical pieces around the base, so those were omitted. I'd guess these don't have a huge effect on stability but you might try deleting them in RS and seeing what difference it makes.
__________________
Rich Holmes Camillus, NY Secretary / newsletter editor Syracuse Rocket Club http://richsrockets.wordpress.com |
#8
|
|||
|
|||
The three motors listed in the supplied sims are not in the database. The rod length in sims 0 and 1 is 1.22mm. Trying to run a sim with other motors (in the database) gives all zeros in the data columns, as if the igniter misfired. Time to call/e-mail Apogee.
__________________
Clear skies and fair winds, Mike NAR 31689 |
#9
|
|||
|
|||
I emailed Apogee and they sent me an updated RockSim file that is stable! If your file has the escape tower on the Command Module it won't work.
Thanks everybody!
__________________
Roy Tuinila CMASS Member NAR #90252 NARTREK Bronze L1 w/Mega Der Red Max on an H87-IM-7 |
#10
|
||||
|
||||
Put clear fins with no net spin ala Centuri. Use longer burning motors of 1.5-2.5 seconds. Short delay and huge chute(s).
Jerry |
Thread Tools | Search this Thread |
Display Modes | |
|
|