1. OpenRocket Simulation Software NARCON – Mar 13, 2010 Kerry Quinn NAR# 88941 FoxValleyRocketeers Woodstock, IL

2. OpenRocket Why Run Simulations Anyway ? What is OpenRocket How does it compare to… Interesting O.R. mini-studies Could I model a ______ with OpenRocket? Live Demonstration

3. Motor / Wind / Altitude Interactions Stability Questions Educational – Math/Physics When It’s too cold to fly real rockets It’s fun Advanced Flights (dual deploy, air-start etc.) Contest Flying / Optimization Kit Mods / Scratch Building Why Run Rocket Simulations ? You will be smarter than the average bear All Rocketeers Some Rocketeers

4. The “Big 5” Rocketry Questions… 1)Altitude 2)Stability (speed at tip of launch rod?) 3)Duration of flight / how far will I have to walk? 4)Motor & Ejection delay to use 5)Speed & altitude(s) at chute(s) deploy Note: 6) Can I afford to get into HPR ? 7) Will anyone beat Chad at nationals?

5. Evolution of a Rocketeer… * Ref: Essence Model Rocketry Site (EMRR) www.rocketreviews.com * Wylie: more of a build-it & fly-it guy… Step 1: ExcitementStep 2: Excitement, tempered by knowledge Step 3: Understanding, punctuated by aspirin and less frequent flying Step 4: Mastery, with safer flights & shorter walks to recovery (lighter wallet)

6. What is OpenRocket ? OpenRocket 0.9.5 is a rocket design and 6 DOF flight simulator, very similar to Rocksim … Written by Sampo Niskanen as part of his Master’s Dissertation in 2009 at the Helsinki University of Technology: “Development of an Open Source Model Rocket Simulation Software” Includes detailed theory manual and sourcecode (java) Website: http://openrocket.sourceforge.net/

7. Sampo Niskanen Sampo Sampo’s Brother Antti Hybrid Rocket Launch for a science program on the Finnish Broadcasting Company – February 2010

8. So is it “like Rocksim” ??? VCPwRASPSpaceCADRocksimOpenRocket PriceFree $ 55$ 120Free Compute CP & CGYesNot autoYes Compute CdlimitedYes Predict AltitudeYes Predict Descent speed & duration Yes Effect of WindYes StagingYes ClusteringYes Effects of Surface finishNoYes Fin CantNoYes Dual DeployNoYes Print TemplatesYes No Generic Fin ShapeNoYes Viewing AnglesYesAnySide, end Shaded ViewsYes No Flight AnimationsNoYesNo Effect of AtmosphereYes Standard Part Names?YesNo Dynamic StabilityNoYes Tube FinsNoYesNo External PodsNoYes Visual, no aero Non Axisym ThrustNo? Export DataYes Kerry Conclusions: Much more capable than VCP & wRASP No capabilities exceeding Rocksim Biggest short comings relative to Rocksim:  No standard part naming (doesn’t know “BT-50” for example)  No aerodynamic calcs for “exterior pods”  No tube fins  No Printing (see later in this talk)

9. wRASP – a tried and true friend…. wRASP: If you know: diameter Cd mass engine You can predict: altitude, accel & velocity at launch rod tip

10. When looking to something new, compare it to what you “know” already… wRASP: you ‘pick’ the Cd (combo of finish and “dragginess”) O.R.: you ‘pick’ the surface finish, O.R. calculates the geometry drag

11. Comparison: Rocksim & OpenRocket (& altimeter) B4-4 engineC6-3 engineFinish Actual64.0 m151.5 m OpenRocket74.4 m +16%161.4 m +7% Regular Paint (60um) RockSim79.1 m +24%180.1 m +19% “matt finish” * Analyses based on measured mass and CG. * Both simulations are similar, both over-predicted altitude OpenRocket Actual RockSim OpenRocket Actual RockSim B4-4C6-3

12. OpenRocket Main Screen 1. “DESIGN TREE” 4. “DESIGN PARAMS” 3. “QUICK SIM” 2. “MODEL VIEW” Drag and drop operation Quick Sim and Params update on-the-fly Quick Sim is “rough estimate” of performance Only “side” and “back” model views available

13. 1. Model, Quick Sim and Params update as you enter values or slide sliders 2. Large library of materials and Surface finishes built-in 3. Fins can be a “set” or treated Individually. Any shape possible.

14. Typical Simulation Results Dual Deploy Chute Weathercock & Drift Drag, Stability and Mass by component

15. OK… but what’s great about 6DOF simulation ? You can predict trajectory as function of CG/CP and wind interactions…. Launch rod Orientation vs. Time Side view of launch Maybe they should have used OpenRocket… wind

16. Spin Stabilization Individual Fins Add Cant Roll Rate (70 rpm) Azimuth 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

17. Looking beyond 3FNC designs … Barrowman eqns require minimum 3, equal spaced fins…. But no such restriction in OpenRocket… 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 !!!* * This flight profile is NOT recommended

18. A couple of “mini-studies” with OpenRocket ….. Thinking about launching a low-stability rocket on a windy day … ? rocket cartwheels above 12 mph wind a little fin-cant increases stability up to 17 mph What if you build make 4FNC rocket but don’t get all fins exactly 90 degrees apart ? at 90/90/90/90 you get 755 ft altitude at 90/90/92/88 you get only 631 ft Maybe that Rose Finjig is worth it after all ?

19. Does surface finish really matter? Age old questions… Can I skip some of these steps ? Painting at all “Polishing” Airfoiling fins

20. Here is where to spend your effort… Paint your rocket & Airfoil the fins for best altitude

21. Rockets, blowin’ in the wind… For a shorter walk, lower altitude: aim into the wind … wind Note: a 1 DOF simulator, like wRASP, won’t tell you ANY of this…. Launch Rod Angle

22. What goes up…. If it is “overly stable” it will: a) weathercock b) lawn-dart recover wind

23. “Two Fins and Nose Cone” ? (!) Some things are best left to VIRTUAL reality wind

24. 2 FNC...don’t try this at home… wind … 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. If there is no restoring force, the rocket cartwheels …. +90 zenith = towards sky -90 zenith = towards ground

25. What’s so great about 6 DOF ? Unstable FlightsUnstable Flights 2Unstable Flight Unstable Flight 1

26. What can I build in OpenRocket? Leading Edge Rocketry “Phantom”

27. What can I build in OpenRocket? Semroc Hydra 7

28. One more reason for simulation… to predict where it will land… The author, launching his Hydra VII Mark Bundick, retrieving the Hydra from the Woodstock swamp… (thanks again Mark)

29. What can I build in OpenRocket? Fliskit Decaffinator O.R. warning about “stepped geometry”, predicted an altitude of 296 ft on D12-7

30. What can I build in OpenRocket? Quest “Totally Tubular” O.R. doesn’t recognize tube fins – so CP and stability are incorrect – you can “build it”, but NOT “fly it” in OpenRocket!

31. What can I build in OpenRocket? T-65 X-wing fighter

32. What can I build in OpenRocket?

33. Planned Enhancements for OpenRocket… Aerodynamic computation using CFD Better support for supersonic simulation 3D view of the rocket design Saving figures and exporting simulation data Importing and plotting actual flight data from altimeters Importing new motor thrust curves Support for ready-made component databases Customized support for hybrid rocket motors and water rockets Rocket flight animation A "wizard" for creating new rocket designs Automatic “Engine Picker / Comparison tool” Listener plug-in apps (see below) 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.

34. I can’t print from OpenRocket? (!) There is not yet a built-in feature in OR for printing (as of ver 0.9.5) Kerry has developed a stand-alone print utility called “Orutil.exe”* - fin templates (trapezoidal, elliptical and free-form) - transition templates -“estes-style” wrap-around fin/lug alignment guide Written in ‘python’ sourcecode and Windows 32bit compiled versions available: www.foxvalleyrocketeers.org/myframes/reports.htm * Special thanks to Dean Thorne for help in testing and in suggesting features.

35. ORutil Printing Process 1. Create Model in OR 2.Run the OR model file thru ORutil 3. View/print resulting *.htm file using Internet Explorer 1”x1” square

36. Summary OpenRocket has much of the Rocksim feature set… for FREE (6 DOF simulation is now available to everyone) OpenRocket is easy to use 6 DOF simulation provides much more insight than 1 DOF: stability, roll, wind, AoA etc… (and it is fun to try)