Red Columbine - A Rocket Based On A Flower

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Do you want a 3D printed version of this? Would be a pretty easy design to create in Tinkercad so you can 3D print a field of them -- or should I say a Rocket Garden full of them ;)

Thanks for the offer... but nope, I'm good.

For me.. it's the thrill of the build, figuring out how to make something with my own 2 hands.
 
The swing test for this rocket seemed rock solid stable, yet the Open Rocket simulation reflected a stability caliber of only 0.189.

I went back and updated the Open Rocket Simulation to have the base vortex cone discussed in the Apogee Peak of Flight Newsletter #145.

This change increased the stability caliber from 0.189 to 0.642. Additionally I think the wide fin profiles and the sphere's produce enough drag that the stability is likely higher than 1 caliber.

2022-02-22 Open Rocket Simlulation Red Columbine.jpg
 
The swing test for this rocket seemed rock solid stable, yet the Open Rocket simulation reflected a stability caliber of only 0.189.

I went back and updated the Open Rocket Simulation to have the base vortex cone discussed in the Apogee Peak of Flight Newsletter #145.

This change increased the stability caliber from 0.189 to 0.642. Additionally I think the wide fin profiles and the sphere's produce enough drag that the stability is likely higher than 1 caliber.

View attachment 505851
My mindsim says that the spheres at least will have quite a bit of base drag. I'd say the same of the wide fins, but I'm not sure how the very canted trailing edge impact that in the real world.
 
If your swing test was rock stable, then I would feel pretty good about launching myself. I would probably err on the side of caution for the first couple flights, i.e. still day, plenty of initial thrust, and if possible a longer rod; but I'll personally be in the surprised camp if it isn't a safe flight.

To me it looks a lot like a shuttlecock, and we know those will fly with a rocket motor in them.
 
To me it looks a lot like a shuttlecock, and we know those will fly with a rocket motor in them.
Yes, that.

I have a rocket that swing tested rock solid, even to the extent that I could dip the swing until the rocket brushed the ground and started to tumble, and it recovered quickly. I even repeated that "bump" test, did it two or three times. Then the rocket went sky writing. So...
I would probably err on the side of caution for the first couple flights, i.e. still day, plenty of initial thrust, and if possible a longer rod...
and if possible a long launch control wire. But I do expect it'd be good, thanks to it's resemblance to a shuttlecock.

I went back and updated the Open Rocket Simulation to have the base vortex cone discussed in the Apogee Peak of Flight Newsletter #145.
How did you arrive at that cone size? If I remember the article correctly, the base of the cone is supposed to be the same diameter as the base of the rocket body. Your cones appears to be much bigger around than your body tube.
 
How did you arrive at that cone size? If I remember the article correctly, the base of the cone is supposed to be the same diameter as the base of the rocket body. Your cones appears to be much bigger around than your body tube.

Body tube is BT-80 = 2.60 diameter

Cone Dia = 2.50

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Columbine Launch Report  2022-06-30.jpg
I gained a lot of respect for you folks that post up flight videos and photos. We were so focused on not losing the rocket since it was its maiden flight, that I wasn't able to get any apogee or recovery photo's.

So... my apologies in advance for the poor-quality photos and video.

Columbine Launch 001.jpgColumbine Launch 002.jpgColumbine Launch 003.jpgColumbine Launch 004.jpg

Columbine Launch 006.JPGRed Columbine Cropped.JPGColumbine Launch 007.JPGColumbine Launch 008.JPG

 
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Launch Report

My wife and I launched the Red Columbine.

The rocket flew rock solid stable on an Estes D12-3 BP motor. An impressive rocket to watch due to its non rocket looking profile.

This is a rear eject spool design and there were no issues with deployment. It's my first scratch build design to utilize rear eject, as well as a nylon 18" parachute. I'm a fan.

No damage occurred upon ground impact.

I gained a lot of respect for you folks that post up flight videos and photos. We were so focused on not losing the rocket since it was its maiden flight, that I wasn't able to get any apogee or recovery photo's.

So... my apologies in advance for the poor-quality photos and video.

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Congrats on her completion and maiden flight/recovery! Beautiful flying field too.
 
Your builds and documentation have been great. It is however wonderful to see that mirrored in the execution of the designs. Congrats! The proof is in the pudding, as they say.
 
Here's a more refined Open Rocket Simulation, made using a wrap based on a photo from the as painted rocket. Also updated the curvature of the nose cone to more accurately reflect the as built contour. I'm trying to drill down on the actual stability number to use as a baseline for future builds.

2022-10-09 Open Rocket Simlulation Red Columbine.jpg
 
I figured I'd re-post this "Base Drag Discussion" here since I used this rocket as a case study

I seem to get more realistic Sims leaving the base drag cone in there....but my sample size is low and I'm using an Estes altimeter, so scientific my results are not.

I always leave the cone in place during the simulation. Don't forget to override the mass of the cone to zero.

If the design is marginally unstable without the cone, it may still simulate without the cone in place, but the data is bogus.
If the design is very unstable without the cone, the simulation will show it as such and the simulation will show an erratic flight when you look at the plot.

Let's use my Red Columbine rocket as a case study.

I built this rocket and it passed a swing test. It then flew successfully on a D12 and was recovered undamaged. The flight was very stable, with a guestimated apogee of about 300 feet... just as the simulation shows with the base drag hack cone in place.​

2022-11-15 ORSimWith Base Drag Hack.jpg2022-11-15 ORSim PLot With Base Drag Hack.jpg


Now let's remove the base drag hack cone. That simulation shows an unstable flight with an apogee of about 100 feet. The rocket ground hits before the chute is ejected. The simulation does not represent what actually occurred during the flight.​

2022-11-15 ORSim Without Base Drag Hack.jpg2022-11-15 ORSim PLot Without Base Drag Hack.jpg
 
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