Stop Sign Test Bed with AirBrake Recovery

stealing another design from @neil_w
Modifying it a bit to fit my Air Brake Technique.
Got a GREAT flight today, much better than expected, on C6-3
Video not great (at least shows that it was stable on the way up, little bit of a corkscrew at the end)
Video didn't get the recovery, I should have gone with the B6-2 as it was too high to see and even with the minimal wind it drifted. Minimal rotation (those "Stop Sign" hemi-fins really restrict the rotatory motion.)

Did something different with the deployment technique, instead of rotor stops (which look like canards and mess with stability), this uses carbon fiber tubes, sliding over monofilament fishing line, pulled on the inside with rubber bands. Huge improvement in aerodynamics/drag reduction.

Since this works, I will upgrade it to 24mm D engine, which will give me a bit more space to work with for the STOP lettering.

Anyway, I've been commenting on a lot of builds lately, didn't want people to think I was trolling and not building anything myself.

No point in watching video past first seconds after launch, despite a perfect deployment, was just too high to see and too far away to pick up descent. Give you an idea on the hang time though. Given about 6 seconds "up" time, total flight time about 45 Seconds, so had about 39 seconds of hang, landed light as the proverbial feather.
The REALLY sharp eyed will see the rocket at 50 seconds into the video about 1/10 of the way up from the bottom of the screen, 1/3 from the left side, and from 60 to 62 seconds just to the left of the light pole.

Air brake recovery seems perfect for a Stop Sign rocket! That really worked. I'm trying to visualize the internals, where does the motor go?

Interesting. Looks like an external-blade helicopter recovery model but without any attempt to get it to rotate on the way down (flat arms, not angled or airfoiled).

this one you can jump to the end to see the recovery.

Had a perfect rocket morning, winds about 2 mph, park empty (both winds and absence of spectators due to visiting on a weekday at 8:30 a.m. and at least some people still limiting their congregating activities with Covid 19.)

This has a VERY different rotor activation and rotor stop mechanism than most of my Helis and Air Brakes.

The key is a sliding tube (although you could use an attached rod, just a bit harder to attache your lines to the "tips" of the rod) on a monofilament line. I use two tiny key card pieces,m one for attachment and the other for the "pulley" point. These are punched out with a standard hole punch, and then a drill puts a small hole in the middle. The rubber bands are internal, attached to a peg. Like my other rockets, the rotors are held closed by rubber bands at the tail, which create a temporary motor mount "box" (answers @mbeels question, sorry somewhat belatedly). Two rubber bands are used. One band is passed, we'll say from the left rotor to the right rotor through holes in the rotors just in front of the motor. The band is pulled through the holes with a crochet hook. This creates a "loop" on each side, this is pulled back and passed around the back of the motor. So left and right rotors are held close, we have a rubber band pulled tight in front of the motor acting as an engine block (for the moment!), and the rear loops work quite well for motor retention.

Now we pass the SECOND band, we'll say from front to back, through the remaining holes, again just in front of the motor. Again the loops are pulled back around the sides and back of the corresponding rotors and wrapped around the motor. So we have a SECOND segment in front of the motor (a SECOND engine block, the sides hold the rotors closed, and again we have pretty darn good motor retention (you DO have to have between 1/4 and 1/2" of motor sticking out the back to have something to wrap around.)

At apogee (or hopefully close to it!) the ejection charge fires. I have yet (knock wood) had the ejection charge fail to instantly burn through the rubber bands, simultaneously releasing the rotors which hopefully are pulled open by the apparatus above. The motor is free to fall, unless I put a streamer on it (something I am now trying.) I have marked it on the screen save below, my way of appeasing the RSOs!

I have another model I will post a build thread on which gives and option for full motor retention.

I was a bit bummed by this flight in one respect. This thing should NOT have rotated. The "vertical" fins post deployment should have prevented it. Likely at least one of the rotors has picked up a bit of pitch/tilt, which is causing the rotation.

Ah, clever use of those tubes as rotor stops, that makes the front of the rocket a fair bit more streamlined. Even if it wasn't supposed to rotate, it was still a good flight with a stable and gentle recovery!

Genius how you moved the deployment mechanism to the inside to reduce drag and how you streamlined the outside by replacing the chunky stops with thin carbon tubes. That's inspired man.