ANNOUNCEMENT: The OpenRocket 22.02 Beta Period is now finished

[JoePfeiffer]

The MathCAD formulas for spin stabilization effects are on page 5 of a PDF document I have in my spin stabilization subdirectory. I don't know where I got it and searches don't turn it up. The file download date is November of 2017.

ROCKET SPIN STABILIZATION USING CANTED FINS
FINSIM ANALYSIS
October 2002
BY JOHN CIPOLLA AEROROCKET

That could be interesting to see. We'd have to be careful not to use any code or anything else copyrightable, but I'd be interested in the analysis.

It occurs to me that experimenting with spin stabilization is exactly the sort of thing OR's simulation extensions are intended for.

 

[neil_w]

Beta period is officially over, you know what that means: https://www.rocketryforum.com/threa...2-final-is-now-available-for-download.177835/

 

[4regt4]

Beta period is officially over, you know what that means: https://www.rocketryforum.com/threa...2-final-is-now-available-for-download.177835/

Is this different than the recently released RC.01?

Hans,

 

[neil_w]

Yup!

Is this different than the recently released RC.01?

Hans,

Yup!

I mean, not *that* different, but it's worth getting.

 

[SiboVG]

Is this different than the recently released RC.01?

Hans,

There are some changes, yes. You can check out our changelog to see what's changed between RC.01 and the official 22.02.

 

[JoePfeiffer]

Special thanks to everyone who has reported problems and made suggestions during the beta period. Your input has been instrumental in making this release what it is.

 

[bad_idea]

Special thanks to everyone who has reported problems and made suggestions during the beta period. Your input has been instrumental in making this release what it is.

But very, very special thanks to all of you on the development team who have brought OpenRocket back to currency with active development and a boatload of features. You're a magnificent group of devs, and we all owe you a debt of gratitude for your work.

 

[Neutronium95]

Thanks again to the development team. 22.02 has been a great improvement over 15.03, and it's been really great to see active development again.

One thing that would be very nice would be if there could be future releases on something like a quarterly schedule, if only to update the motor database. It was always kind of frustrating to need to grab an up to date set of motor files for 15.03, before the beta came out.

 

[neil_w]

Thanks again to the development team. 22.02 has been a great improvement over 15.03, and it's been really great to see active development again.

One thing that would be very nice would be if there could be future releases on something like a quarterly schedule, if only to update the motor database. It was always kind of frustrating to need to grab an up to date set of motor files for 15.03, before the beta came out.

What, you mean every 8 years isn't often enough? That's some gratitude.

Right now we're aiming for every 6 months or something in that ballpark. We'll see how it goes. At some point we'd like to put something that'll enable the user to update the motor database from thrustcurve.org, rather than needing to wait for a new release.

 

[waltr]

Have a update motor base within OR would be a great feature.

22.02 has been working great. Thanks everyone for to work.

 

[Winston]

Tube Fin BT-80 29mm originally designed on Rocksim

Rocksim 10.5.0f0 simulation:

With motor loaded:
(Rocksim stability equation selected)
CG: 615.21 mm
CP: 712.77 mm
Stability margin: 1.48

Max. altitude: 568.32 ft
Max. velocity: 203.3 ft/s
Optimal delay: 4.28 s
Max. acceleration: 6.12 G (197 ft/s^2)
Deployment altitude: 566.89
Velocity at (48") launch guide departure: 36.15 ft/s
Velocity at deployment: 18.6 ft/s (up)

OpenRocket 22.02 simulation:

With motor loaded:
CG: 613 mm
CP: 790 mm
Stability margin: 2.68

Max. altitude: 625 ft
Max. velocity: 211 ft/s
Optimal delay: 4.76 s
Max. acceleration: 197 ft/s^2
Deployment altitude: N/A
Velocity at (48") launch guide departure: 38.6 ft/s
Velocity at deployment: 27.8 ft/s (up)

1. Tube fins!
2. Sim comparisons: plenty close enough!
3. THANK YOU!

 

[SolarYellow]

Wow. I just went and made a donation, and it said only 35 people have donated. I've used the heck out of it and have gotten personalized help/input from the developers. I'm sure I'll guilt myself into giving more in the future.

Y'all should throw in to the doan jar, too.

 

[SiboVG]

Wow. I just went and made a donation, and it said only 35 people have donated. I've used the heck out of it and have gotten personalized help/input from the developers. I'm sure I'll guilt myself into giving more in the future.

Y'all should throw in to the doan jar, too.

Thank you for your donation! Don't worry, we have plenty of donations for the moment and don't have imminent costs, so we should be good for a while .

 

[neil_w]

Tube Fin BT-80 29mm originally designed on Rocksim

Rocksim 10.5.0f0 simulation:

With motor loaded:
(Rocksim stability equation selected)
CG: 615.21 mm
CP: 712.77 mm
Stability margin: 1.48

Max. altitude: 568.32 ft
Max. velocity: 203.3 ft/s
Optimal delay: 4.28 s
Max. acceleration: 6.12 G (197 ft/s^2)
Deployment altitude: 566.89
Velocity at (48") launch guide departure: 36.15 ft/s
Velocity at deployment: 18.6 ft/s (up)

OpenRocket 22.02 simulation:

With motor loaded:
CG: 613 mm
CP: 790 mm
Stability margin: 2.68

Max. altitude: 625 ft
Max. velocity: 211 ft/s
Optimal delay: 4.76 s
Max. acceleration: 197 ft/s^2
Deployment altitude: N/A
Velocity at (48") launch guide departure: 38.6 ft/s
Velocity at deployment: 27.8 ft/s (up)

1. Tube fins!
2. Sim comparisons: plenty close enough!
3. THANK YOU!

Honestly, there’s a bit more divergence there than I would like to see. Could you post or PM me both files?

 

[cwbullet]

Fantastic job. I am very impressed.

 

[JoePfeiffer]

Tube Fin BT-80 29mm originally designed on Rocksim

Rocksim 10.5.0f0 simulation:

1. Tube fins!
2. Sim comparisons: plenty close enough!
3. THANK YOU!

if you get a chance to put the rocket up with an altimeter, I'd be very curious to be able to compare with your data.

 

[Winston]

if you get a chance to put the rocket up with an altimeter, I'd be very curious to be able to compare with your data.

Will do, but it won't be that one because it's not built and won't be since I have a similar one which I will also sim with the latest sim versions and eventually fly (again). I will say that years ago with that same custom tube-finned model and Rocksim 9, the projected and measured altitudes were amazingly close. I was using Aerotech E20s if I recall correctly.

The following is not about tube fins, but in 2014 I did a half-a**ed test of a six fin design which was a subscale version of a 4" OD design which gave me radically different results from Rocksim vs OpenRocket.

https://www.rocketryforum.com/threa...pr-1-2-altitude-of-rocksim.53242/#post-709474
In that case, with the subscale version at least, OpenRocket was much more accurate than Rocksim when using thick, flat leading and trailing edge fins and only slightly more accurate with the same fins rounded.

The whole point was to be able to safely fly an intentionally draggy 4" version with six 1/4" fins with flat leading and trailing edges. One needs an accurate simulation to know what delay to set. Sims of that was what led to my experiment with the subscale version due to the huge difference in the results between Rocksim and OpenRocket. The 4" version was already built before I discovered that huge difference, but slight coning of the subscale version flying on F32s in the tests made me afraid to ever fly the 4" version which I haven't. Otherwise, I would have flown it definitely using the OpenRocket results.

 

[Winston]

Here's what I should have done in the first place rather than choosing to sim the first tube finned model in my design subdirectory - sim one I've actually flown!

All launch condition settings were correct when I simmed this years ago with Rocksim 9 and remain so and are identical in both Rocksim 10 (RS) and OpenRocket 22.02 (OR).

Mass overrides and actual overall mass were used for everything which just led me to notice that mass override icons are no longer shown next to the applicable components in Rocksim 10 even though the mass overrides are active whereas they are still shown in OpenRocket.

The difference between measured apogee and Rocksim 9 predicted altitude was just a few feet. Of course, chance (normal motor variations, etc.) is heavily involved since I've launched this design, if I recall correctly, only once.

Aerotech E20W-4

Max. alt. - OR 724 ft ; RS 609.85
Max. vel. - OR 231 ft/s ; RS 217 ft/s
Opt. delay - OR 5.05 s ; RS 4.23 s
Max. accel. - 277 ft/s^2 ; RS 8.62 G (277.5 ft/s^2)
48" rod depart. - OR 47.7 ft/s ; RS 46.74 ft/s
Deploy. vel. - OR 34.6 ft/s up ; RS 14.81 ft/s up
CG - OR 716 mm ; RS 716.95 mm
CP - OR 981 mm ; RS 899.68
Stab. fact. - OR 4.01 ; RS 2.77

 

[Winston]

Here's what I should have done in the first place rather than choosing to sim the first tube finned model in my design subdirectory - sim one I've actually flown!

All launch condition settings were correct when I simmed this years ago with Rocksim 9 and remain so and are identical in both Rocksim 10 (RS) and OpenRocket 22.02 (OR).

Mass overrides and actual overall mass were used for everything which just led me to notice that mass override icons are no longer shown next to the applicable components in Rocksim 10 even though the mass overrides are active whereas they are still shown in OpenRocket.

The difference between measured apogee and Rocksim 9 predicted altitude was just a few feet. Of course, chance (normal motor variations, etc.) is heavily involved since I've launched this design, if I recall correctly, only once.

Aerotech E20W-4

Max. alt. - OR 724 ft ; RS 609.85
Max. vel. - OR 231 ft/s ; RS 217 ft/s
Opt. delay - OR 5.05 s ; RS 4.23 s
Max. accel. - 277 ft/s^2 ; RS 8.62 G (277.5 ft/s^2)
48" rod depart. - OR 47.7 ft/s ; RS 46.74 ft/s
Deploy. vel. - OR 34.6 ft/s up ; RS 14.81 ft/s up
CG - OR 716 mm ; RS 716.95 mm
CP - OR 981 mm ; RS 899.68
Stab. fact. - OR 4.01 ; RS 2.77

It just now belatedly occurred to me that it might be useful to attach the appropriate Rocksim and OpenRocket files for this design.