Well, that's a great idea. I have even set up a couple of electric sailplanes (years back), for the ESC's to brake to be sure the folding props folded.

The 4-in-1 ESC I am using, has "BL Heli" firmware. There is an option to set prop brake for BL Heli. I have done only some brief googling to check on use for multicopters. Some multicopter fliers have set their models with BL Heli to use prop brake on throttle down, to instantly stop the props on throttle down (after landing) in case of a bad landing where the props keep trying to spin.

What I need to find out further is whether prop brake for "armed ready for takeoff" mode would work, or not. If it did work, would it interfere with the Throw Mode programming when the model reaches apogee and it tries to start up the motors. I would presume it would not affect the startup, but the bigger question is whether the prop brake would work during the armed and boost phase (it might only work to brake AFTER the throttle has been high first). Must admit I do not recall, with my old electric sailplanes with prop brake, trying to physically rotate a prop by hand when the throttle was off, to see how much physical resistance it provided (which of course would have been risky).

Anyway, I'll check into it, thanks for mentioning it. The more I think about a system using rubber bands and a servo to retract a rod (would be two rods 180 degrees apart, each to release two bands for two props), to secure the props for boost, the more I do think it would work reliably. There's plenty of open space inside the Descent Stage to mount a small servo and mechanism for two retracting rods. So now there's two ways to address the problem.

Someone also pointed out some 3D Printed folding props, suggesting perhaps the files could be mirrored to allow for CW and CCW pairs. But there is a certain concern I have doing that, so I'd prefer to use either the ESC prop brake or tethers released by servo method.

Most future rocket boosts will probably be on an E15 or E18 reload. Although perhaps in calm weather I may try D12's again (Too bad AC Supply Co. does not sell Aerotech motors, as they do for Estes motors at 40% off). The model weighs about a pound without motor.

Gus, of course I plan to fly it at NARAM, as well as the Lunar Module Quad. I SO hope that Vern and Gleda will make it to NARAM. My biggest regret last year was not having time to build and fly this model then, to take to NARAM-60 and ORR.

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