OpenRocket Simulation Software NARCON – Mar 13, 2010. Kerry Quinn NAR# 88941 FoxValleyRocketeers Woodstock, IL. OpenRocket. Why Run Simulations Anyway ? What is OpenRocket How does it compare to… Interesting O.R. mini-studies Could I model a ______ with OpenRocket?
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You will be smarter than
the average bear
Step 1: Excitement
Step 2: Excitement, tempered by knowledge
Wylie: more of a build-it &
Step 3: Understanding, punctuated by
aspirin and less frequent flying
Step 4: Mastery, with safer flights & shorter
walks to recovery (lighter wallet)
* Ref: Essence Model Rocketry Site (EMRR) www.rocketreviews.com
OpenRocket 0.9.5 is a rocket design and 6 DOF flight simulator, very similar to Rocksim …
“Development of an Open Source Model Rocket Simulation Software”
Hybrid Rocket Launch for a science program on the Finnish Broadcasting Company – February 2010
If you know:
You can predict:
altitude, accel & velocity
at launch rod tip
wRASP: you ‘pick’ the Cd (combo of finish and “dragginess”)
O.R.: you ‘pick’ the surface finish, O.R. calculates the geometry drag
* Analyses based on measured mass and CG.
* Both simulations are similar, both over-predicted altitude
1. “DESIGN TREE”
4. “DESIGN PARAMS”
2. “MODEL VIEW”
3. “QUICK SIM”
2. Large library of materials and
Surface finishes built-in
3. Fins can be a “set” or treated
Individually. Any shape possible.
Drag, Stability and Mass by component
Dual Deploy Chute
Weathercock & Drift
You can predict trajectory as function of CG/CP and wind interactions….
Side view of launch
Orientation vs. Time
Maybe they should have used OpenRocket…
Roll Rate (70 rpm)
Fin canting generates spin and can be used to increase stability.
But how much to use? One fin? All fins? What will it do to altitude? Etc…
Simulation lets you quickly test options
Within 0.6 seconds in 10mph wind, rocket goes from 90 degrees “up” to horizontal... and beyond (!)
200 feet up and down in 2.03 seconds !!!*
Barrowman eqns require minimum 3, equal spaced fins…. But no such restriction in OpenRocket…
* This flight profile is NOT recommended
Paint your rocket & Airfoil the fins for best altitude
Launch Rod Angle
For a shorter walk, lower altitude: aim into the wind …
Note: a 1 DOF simulator, like wRASP, won’t tell you ANY of this….
wind2 FNC . . .don’t try this at home…
+90 zenith = towards sky
-90 zenith = towards ground
If there is no restoring force, the rocket cartwheels ….
… If I am uncertain about the safety or stability of an untested rocket, I will check the stability before flight and will fly it only after warning spectators and clearing them away to a safe distance.
Unstable Flight 1
Unstable Flights 2
Leading Edge Rocketry
Semroc Hydra 7
Mark Bundick, retrieving the Hydra from the Woodstock swamp…
(thanks again Mark)
The author, launching his Hydra VII
O.R. warning about “stepped geometry”, predicted an altitude of 296 ft on D12-7
O.R. doesn’t recognize tube fins – so CP and stability are incorrect – you can “build it”, but NOT “fly it” in OpenRocket!
T-65 X-wing fighter
The project is OpenSource with around 200 downloads so far. Author is soliciting help via the GNU system. Another grad student is developing a “listener” drop in code segment for his thesis, the listener gets data from and feeds changes back to the analysis as it progresses – his project is for an active guidance control system.
* Special thanks to Dean Thorne for help in testing and in suggesting features.
1. Create Model in OR
3. View/print resulting
*.htm file using
2.Run the OR model
file thru ORutil
(6 DOF simulation is now available to everyone)