Strange Rocksim results

The Rocketry Forum

Help Support The Rocketry Forum:

les

Well-Known Member
TRF Supporter
Joined
Jan 20, 2009
Messages
2,960
Reaction score
601
I've been working on a design and doing a few tweaks.

I reran some existing simulations.

Using the same motor I get a max alt of either 10182 or 10274 - no problem - expect some minor differences
Max velocity of 1113 or 1114 - again no problem
Time to apogee - 23.36 vs 23.48 - still good

But max acceleration? 370 vs 1541 ft/sec/sec

Say what? Over 4X the accel but every other number "matches"??? What is going on????

File attached....

View attachment ultimate_Darkstar_LRBb.rkt
 

dhbarr

Amateur Professional
Joined
Jan 30, 2016
Messages
7,513
Reaction score
1,947
Acceleration jumps like this in OR as well, you can see it by making very short tubefins for instance.

I haven't taken the time to file a bug report ( shame on me ), but it's fairly reproducible.
 

UhClem

Well-Known Member
Joined
Feb 6, 2009
Messages
1,885
Reaction score
318
Rocksim does not limit itself to just the motor burn time when checking for maximum acceleration. Check your deployment settings.
 

markkoelsch

Well-Known Member
Joined
Mar 18, 2009
Messages
4,364
Reaction score
151
Rocksim does not limit itself to just the motor burn time when checking for maximum acceleration. Check your deployment settings.
You beat me to it. Likely a deployment event
 

les

Well-Known Member
TRF Supporter
Joined
Jan 20, 2009
Messages
2,960
Reaction score
601
OK - found it was the main deployment after coming down on drogue.

The puzzling thing is I've made no changes in the drogue. So why did one simulation have one accel value and a different one have a much larger accel value when the main deployed?
 

markkoelsch

Well-Known Member
Joined
Mar 18, 2009
Messages
4,364
Reaction score
151
Is it setup for drogue deployment at apogee and main at altitude, or was the drogue set to use motor delay?
 
Top