A little late to the OR party... Building an Apogee Zephyr, and I have the rkt file provided by Apogee... I'm assuming I need to weigh my rocket once its all done and painted and edit the weight of it in OR to get fairly accurate data? I see tons of tutorials for building rockets, not so many for how to take an existing rocket file and alter it to reflect the rocket you build.
Using OpenRocket for an existing rocket...
- Thread starter danielhv
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Yes, exactly. Double check the weight as built vs the sim. And set the finish quality, be honest, as constructed it's rougher than you think.
Also, for each sim run, set the atmospherics as would be at the actual launch pad. That's the latitude and longitude, altitude, barometric pressure, temperature, and humidity. That will get your sim to within a few percent of actual.
If you have flown the model, use actual atmospherics, and flown altitude to diddle the Cd so the sim matches the real result.
Also, for each sim run, set the atmospherics as would be at the actual launch pad. That's the latitude and longitude, altitude, barometric pressure, temperature, and humidity. That will get your sim to within a few percent of actual.
If you have flown the model, use actual atmospherics, and flown altitude to diddle the Cd so the sim matches the real result.
For best results weigh components and enter actual values. Quick & dirty by overriding final weight and CG on sustainer.
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If the rocket is complete, weigh it. Assuming the rocket is actually heavier than the Apogee sim, then locate the Center of Gravity (where it balances). Add a Mass Object with the weight to match the difference, and position it to get the CG to match
Weigh the rocket WITHOUT the motor. Balance the rocket on your finger without the motor and measure the distance from the nose tip to that point.
Right-click the Sustainer(at the top of the component tree list) and select edit OVERRIDE THE MASS FOR ALL SUBCOMPONENTS with the measured mass.
Override the center of gravity for all subcomponents.
CG AND MASS will automatically update for the motor selected. If you have the actual motor, you can check by balancing the assembled rocket with the motor on your calibrated finger.
You can set your location atmospheric conditions if you want. If you're only going 1000-2000 ft up, it won't make any significant difference. If it's a competition launch or altitude record or high launch, it's worth doing.
Norm
Right-click the Sustainer(at the top of the component tree list) and select edit OVERRIDE THE MASS FOR ALL SUBCOMPONENTS with the measured mass.
Override the center of gravity for all subcomponents.
CG AND MASS will automatically update for the motor selected. If you have the actual motor, you can check by balancing the assembled rocket with the motor on your calibrated finger.
You can set your location atmospheric conditions if you want. If you're only going 1000-2000 ft up, it won't make any significant difference. If it's a competition launch or altitude record or high launch, it's worth doing.
Norm
@danielhv --
@RocketScientistAustralia's advice for setting Dry Mass and CG without a motor is very simple and seems to work very well for me too.
But before I ever get to the point of overriding the Dry Mass and CG, I've had some .rkt files from the internet import with errors on OpenRocket for Linux.
The way I handle RockSim.rkt in OpenRocket is this:
Open the original .rkt and then save as an OpenRocket.ork file and exit OR.
Then rerun OpenRocket on the newly converted .ork file.
OR seems to work better if I start up with an OpenRocket.ork file in subsequent sessions.
Like @cls, I set my launch site conditions 'because I can' and all of my finishes are 'Unfinished' because they usually are
As always, YMMV ...
-- kjh
EDIT: p.s. I've also weighed components as @Joekeyo recommended but I usually end up with final Dry Mass and CG overrides as above ...
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