Who is experimenting with full electric/electronic deployment?

[Tyler P]

After leafing through Sport Rocketry this month I saw that some are working on electric deployment vs the more traditional bp charges. I have to say that this intrigues me greatly.

Has anyone started trying electric/electronic separation to deploy drogue chutes and mains instead of charges? I'd like to look into this for duel deploy in the future.

 

[jnobels]

For main deployment, I’ve been doing my own servo chute releases for a while. A 9g servo, small sled and an elastic band triggered by a custom altimeter. Very reliable once I got it dialled in.

 

[cerving]

For very high altitude flights, a trapdoor would be a good option. The trick is making it fit well enough and venting the parachute bay properly so that it doesn't pop open prematurely. FYI, the Eggtimer Classic, Quantum, and Proton all support servos natively, with no additional driver circuitry.

 

[Tyler P]

I think I'm going to go the eggtimer route and try to do dual-deploy without bp. I have some ideas bouncing around my head for a bungee eject, which should be pretty simple to do.

 

[djmartins]

For main deployment, I’ve been doing my own servo chute releases for a while. A 9g servo, small sled and an elastic band triggered by a custom altimeter. Very reliable once I got it dialled in.

Sounds like an improvement on BP.

 

[Nytrunner]

Will this method break up the rocket's form factor?

If a drogue fouls or tangles, at least the rocket is broken and no longer ballistic. If a trapdoor or rubberband snags and the chute doesn't come out, you still have a projectile with much higher terminal velocity

 

[Tyler P]

Will this method break up the rocket's form factor?

If a drogue fouls or tangles, at least the rocket is broken and no longer ballistic. If a trapdoor or rubberband snags and the chute doesn't come out, you still have a projectile with much higher terminal velocity

I would think you could potentially have a BP charge not separate a rocket as well, although it's definitely a more proven method.

What I'd like to try is an elastic-powered ejection to separate and a chute release to unfurl the chute. I have an unbuilt Estes Argent that I might give it a go with.

I envision it as being a chute release kind of pin system using a tight elastic pulled like a slingshot inside the rocket with the laundry loaded on a small sled, maybe even on an internal rail system. Using an altimeter, or accelerometer, trigger the sled to launch at apogee either at altitude or reduction in acceleration. The force of the sled is what would separate the rocket and potentially release a drogue, and then the chute release would do the rest of the job unfurling the chute.

I think the key would be making sure the rocket halves are loose-ish, being held together with the force of the bungee sled launcher, and designing the sled to come out with enough speed to pop the upper half off easily.

The larger the scale of the rocket, the harder it would be to make it work due to the need for much larger bands/bungees but I think I could make it work on a 3" rocket.

Definitely doable for mid-power and probably L1 high-power.

 

[Nytrunner]

Interesting. Anything with catapult in the name is worth pursuing in my opinion.

Are you thinking of pre-loading the spring unit outside the rocket, then hooking it up to the shock cord and inserting it in the airframe? At a small rocket size that could be generally harmless, but you're still holding an appreciable amount of stored energy.

 

[prfesser]

A friend of mine came up with a parachute release powered by a mousetrap. Really. It'd require a large diameter tube, and I don't think he actually tried it in a rocket. That, or a similar method involving a tightly coiled spring as the energy source, might be worth pursuing.

 

[Nytrunner]

A turkish or Egyptian team at IREC (back when I was a competitor) Had a great device with a HEAvy spring for deployment. A stepper motor controlled a 3/4 (or 18mm?) bolt that engaged a nut on the spring's mounting plate, and the pusher piece on the other airframe section. The spring plate would be aligned with the pusher, and the bolt would screw them both towards it's motor into the airframe. The spring plate hit a coupler or shelf, and the pusher would be cranked back further and compress the spring. At the appropriate time, the alt signaled the bolt to unscrew, the pusher would disengage first and eject the forward airframe.

What I'm annoyed about is that I can't remember their harness setup.

 

[jlabrasca]

A friend of mine came up with a parachute release powered by a mousetrap...

The tricky part is training the mouse to ignore the bait until after the rocket noses over...

https://www.smithsonianmag.com/smithsonian-institution/bf-skinners-pigeon-guided-rocket-53443995/

https://www.theatlantic.com/technol...rd-tech-the-bat-bombs-of-world-war-ii/237267/

@John Beans made an excellent point in his Rocketry 2.0 talk. We think in terms of positive ejection because that is how pyro works -- but really, all that is necessary is that airframe falls apart and exposes the recovery gear. It doesn't take that much energy to release a latch or two.

 

[cerving]

The Vashon Valkyrie (cold power) rockets had a little pressure-actuated flat spring that latched onto the payload bay, when the pressure in the motor dropped the spring would retract and the payload bay would fall off. (The pressure drained out through a couple of paper disks to slow the venting rate). Pretty ingenious, really. I think most of the "fall off" schemes would be fine for LPR and maybe L1 HPR, but it would be very difficult to make them work for L2 and above. The forces are just too strong...

 

[Tyler P]

Interesting. Anything with catapult in the name is worth pursuing in my opinion.

Are you thinking of pre-loading the spring unit outside the rocket, then hooking it up to the shock cord and inserting it in the airframe? At a small rocket size that could be generally harmless, but you're still holding an appreciable amount of stored energy.

I was thinking that the loading system would be setup inside the rocket, but making it a cartridge that could be locked into place would make setup a lot easier I think, especially on a smaller rocket. On a larger rocket you would definitely want to have a locking pin safety that you would remove once the rocket is on the rail. Pretty simple to make it completely unable to deploy until removal of the safety.

I'm starting to think I'm going to try it on a LOC airframe to start, as I'm going to want the beefier tubing. The PSII tubing on the Argent might be a little light-duty for what I'm thinking of trying.

Should be an interesting project for the winter, I think.

 

[bdureau]

A friend of mine did it with some spring

 

[the random rocketer]

Air Command Water Rockets has a system along the lines you are discussing. They are using a servo and catapult mechanism. See their 2 stage water rocket part 12 on you tube. I don't know if I would trust this on a HPR, but it looks like this is where we're headed.

 

[artapplewhite]

I did some experimenting with monofilament fishing line and a rubber band for a parachute release. A nichrome wire is heated up by an altimeter (StratologgerCF) at a preset altitude to melt the monofilament and release the parachute. It's still a work in progress.

 

[Adrian A]

Glad to see this thread. I'm working on a new Featherweight product that has servo pwm output channels that can be set up to respond to the deployment logic.