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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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openrocket simulation software narcon mar 13 2010

OpenRocket Simulation SoftwareNARCON – Mar 13, 2010

Kerry Quinn

NAR# 88941

FoxValleyRocketeers

Woodstock, IL

openrocket
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
why run rocket simulations
Why Run Rocket Simulations ?
  • 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

All Rocketeers

You will be smarter than

the average bear

Some Rocketeers

evolution of a rocketeer
Evolution of a Rocketeer…

Step 1: Excitement

Step 2: Excitement, tempered by knowledge

*

Wylie: more of a build-it &

fly-it guy…

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

what is openrocket
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/
sampo niskanen
Sampo Niskanen

Sampo’s Brother

Antti

Sampo

Hybrid Rocket Launch for a science program on the Finnish Broadcasting Company – February 2010

so is it like rocksim
So is it “like Rocksim” ???
  • 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)
wrasp a tried and true friend
wRASP – a tried and true friend….

wRASP:

If you know:

diameter Cd

mass engine

You can predict:

altitude, accel & velocity

at launch rod tip

slide9
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

slide10

Comparison: Rocksim & OpenRocket (& altimeter)

RockSim

RockSim

B4-4

C6-3

OpenRocket

OpenRocket

Actual

Actual

* Analyses based on measured mass and CG.

* Both simulations are similar, both over-predicted altitude

openrocket main screen
OpenRocket Main Screen

1. “DESIGN TREE”

  • 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

4. “DESIGN PARAMS”

2. “MODEL VIEW”

3. “QUICK SIM”

slide12

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.

typical simulation results
Typical Simulation Results

Drag, Stability and Mass by component

Dual Deploy Chute

Weathercock & Drift

ok but what s great about 6dof simulation
OK… but what’s great about 6DOF simulation ?

You can predict trajectory as function of CG/CP and wind interactions….

Side view of launch

Launch rod

wind

Orientation vs. Time

Maybe they should have used OpenRocket…

spin stabilization
Spin Stabilization

Roll Rate (70 rpm)

Add Cant

Individual Fins

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

looking beyond 3fnc designs
Looking beyond 3FNC designs …

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

a couple of mini studies with openrocket
A couple of “mini-studies” with OpenRocket …..
  • 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 ?
  • 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
does surface finish really matter
Does surface finish really matter?
  • Age old questions…
  • Can I skip some of these steps ?
  • Painting at all
  • “Polishing”
  • Airfoiling fins
here is where to spend your effort
Here is where to spend your effort…

Paint your rocket & Airfoil the fins for best altitude

rockets blowin in the wind
Rockets, blowin’ in the wind…

Launch Rod Angle

wind

For a shorter walk, lower altitude: aim into the wind …

Note: a 1 DOF simulator, like wRASP, won’t tell you ANY of this….

two fins and nose cone

wind

wind

wind

wind

“Two Fins and Nose Cone” ? (!)

Some things are best left to VIRTUAL reality

2 fnc don t try this at home

wind

wind

2 FNC . . .don’t try this at home…

+90 zenith = towards sky

-90 zenith = towards ground

wind

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.

what s so great about 6 dof
What’s so great about 6 DOF ?

Unstable Flight 1

Unstable Flights 2

what can i build in openrocket
What can I build in OpenRocket?

Leading Edge Rocketry

“Phantom”

one more reason for simulation to predict where it will land
One more reason for simulation…to predict where it will land…

Mark Bundick, retrieving the Hydra from the Woodstock swamp…

(thanks again Mark)

The author, launching his Hydra VII

what can i build in openrocket2
What can I build in OpenRocket?

O.R. warning about “stepped geometry”, predicted an altitude of 296 ft on D12-7

Fliskit Decaffinator

what can i build in openrocket3
What can I build in OpenRocket?

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

Quest

“Totally Tubular”

planned enhancements for openrocket
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.

i can t print from openrocket
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.

orutil printing process
ORutil Printing Process

1”x1” square

1. Create Model in OR

3. View/print resulting

*.htm file using

Internet Explorer

2.Run the OR model

file thru ORutil

summary
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)
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