Searching for "Elegant" stage release, side booster release

[PayLoad]

I'm trying to design a positive-hold, positive release mechanism using an RC servo. I know 99% of stages are friction/shear pin retained, and I wanted to make something electronic (RC Servo inserts/retracts pins?)

I don't want to re-invent the wheel if this has been done before. Any ideas?

 

[PayLoad]

Hmmm - using a push/pull 12v magnet for booster hold/release. Best I can come up with so far

 

[Funkworks]

A knot and to release the booster, elegant robotic fingers will untie the knot.

If anyone tells me you've seen knot-tying robotic hands (let alone un-tying), I want a link. Not there yet, but how nice it would be. Because after thousands of years of footwear, laces are still the best and you know that just once in a while, you'll make the wrong kind of knot and curse because its too tight and spend a minute trying to untie your own mistake. My kingdom for a robotic knot un-tyer.

Oh and I like the electro-magnets but who knows how much battery and current you'll need to keep those boosters attached. Weight matters.

 

[PayLoad]

Thank you for your reply - the solenoid is extended with no power, retracts with power - booster would "snap" on to the sustainer, then a 9V charge will retract the rod, releasing the booster. That's the theory anyway. "elegant = something electronically controlled not using explosives"

 

[dr wogz]

My kingdom for a robotic knot un-tyer.

What about a CNC laser cutter? won't "undo" the knot in the traditional sense, but your shoe lace will have no tension..

 

[PayLoad]

Sorry - just looking for ideas. Advance the sport and all such stuff

 

[Antares JS]

Your solenoid-actuated holding pin is pretty interesting.

A project using this is far in the future, but idea that I have had is to have a system similar to the Apogee booster kit, but instead of blowing the nose off to release, have a coupler tube inside the main tube that is able to move back and forth to release and latch. I probably would have actuated it with an electronically-controlled BP charge, but something like this might work with a linear servo.

The point of this in my mind is to allow the booster to come off in one piece without ejecting anything, reducing the chance of entanglement with the main rocket. It can eject a recovery device a second or two after it separates.

 

[PayLoad]

Your solenoid-actuated holding pin is pretty interesting.

A project using this is far in the future, but idea that I have had is to have a system similar to the Apogee booster kit, but instead of blowing the nose off to release, have a coupler tube inside the main tube that is able to move back and forth to release and latch. I probably would have actuated it with an electronically-controlled BP charge, but something like this might work with a linear servo.

The point of this in my mind is to allow the booster to come off in one piece without ejecting anything, reducing the chance of entanglement with the main rocket. It can eject a recovery device a second or two after it separates.

I like.

Secondary requirement was to have 100% of the hardware in the booster itself, nothing hanging off the sustainer after ejection.

 

[Antares JS]

I like.

Secondary requirement was to have 100% of the hardware in the booster itself, nothing hanging off the sustainer after ejection.

You could reverse the apogee system, putting the hooks on the booster and the holes for the hooks in the sustainer. This would also have the advantage of only having to actuate one coupler tube to release both boosters rather than syncing the release inside each booster.

 

[PayLoad]

Damn slick idea -
This is going on MoonShot, 3 boosters. Existing Apogee hardware won't handle G80

 

[Antares JS]

Damn slick idea -
This is going on MoonShot, 3 boosters. Existing Apogee hardware won't handle G80

More than likely. The apogee hooks are pretty weak. You would probably need to get something made out of hard wood or metal. I wonder if a flat plywood hook would work, with a through-the-wall mount like a fin, with the root of the hook being epoxied to the inside of the tube opposite the slot.

 

[cerving]

How about nylon explosive bolts... easy to fire with just about any altimeter.

https://www.apogeerockets.com/education/downloads/Newsletter266.pdf

 

[mbeels]

Thank you for your reply - the solenoid is extended with no power, retracts with power - booster would "snap" on to the sustainer, then a 9V charge will retract the rod, releasing the booster. That's the theory anyway. "elegant = something electronically controlled not using explosives"

That's very similar to what John Coker is doing with his Arianne 6, check it out:

http://www.jcrocket.com/ariane6.shtml

 

[Antares JS]

How about nylon explosive bolts... easy to fire with just about any altimeter.

https://www.apogeerockets.com/education/downloads/Newsletter266.pdf

That's pretty slick and I like it, but I believe OP is looking for non-pyro though.

 

[PayLoad]

How about nylon explosive bolts... easy to fire with just about any altimeter.

https://www.apogeerockets.com/education/downloads/Newsletter266.pdf

DROOLWORTHY -

ONLY concern is parts of exploded bold would go in sustainer & booster, and too much "ooomph" may blow nosecones off prematurely

 

[mjennings]

Magnetic connection sounds cool but isn't the magnetic bond weaker in shear loading? All the thrust from the booster will transfer through the magnets unless a thrust structure connects them somewhere. Cool brain storming though.

 

[boatgeek]

Another option:
* Tab at the base of the booster that contacts the bottom of the center core, to transfer thrust. It should also have some kind of keying to keep the booster in place. The easiest way to do this would be to cut a small slot in the center core and have a vertical tab that fits the slot.
* At the top of the side booster, run a pin into the center core. The pins from each side meet in the middle and are held in place with a servo pin as described above. When the servo retracts, the tops of the boosters are free to fall off to the side. There will need to be some kind of bearing to hold the pin to the center core, but it shouldn't be too large or it might jam as the booster falls away.
* Add a spring (or maybe very strong magnets) to give the side booster a starting push. Once they start falling away, they should keep going but of course this will need some ground testing. It might be easiest to mount the spring in the side booster pushing off at the exact location of the pin.

 

[jqavins]

(Haven't read it all yet.)

There's a device from TiNi Aerospace for releasing things like big reflector dishes and solar panel wings that uses a shape memory alloy (e.g. Nitinol) to depress the "button" on a ball lock*. It could be downscaled. I don't know about how easily, but I know it could be. And it would be elegant.

Honestly, a solenoid is probably a better choice, but this is brainstorming, right?

Ball lock keychains are a common example. Imagine a Nitinol wire stretched into a horseshoe over the button. Run a current through the wire, it heats up to the transition temperature, which makes it shrink and push the button. The other piece is spring loaded to separate once it's released.

 

[cerving]

I saw that somebody used drawer slides to mount their side boosters, if you have a stop at the top and some kind of release on the bottom that should work. The key thing is that the release shouldn't take any thrust loads... it's just there for retention so that when you let it go the drag will slide the boosters right off.

 

[MadRocketer]

I’m using just three points of contact and drag on the fins to pull it off and away. A burn string will hold the side boosters up before ignition. If the motor fails to ignite it’ll go for a ride. Might include a pivot point at the base of the sustainer to push it away from the flame. Still a work in progress.

 

[PayLoad]

Where/when the lines intersect at installation, at that point is a solenoid/pull pin. This will release the booster, with no hardware left behind on the sustainer

 

[OverTheTop]

Solenoids are quite heavy. What about a micro servo operating a mechanical cam mechanism? Those tiny servos are very light.

 

[jqavins]

Solenoids are quite heavy...

Found this at DigiKey with about two minutes of searching. 5.44 grams

 

[OverTheTop]

The question is does it have the relevant specifications for the needed mission? Force, travel, voltage, current? Servo will be in the same ballpark for mass but you get a gearbox you can drive a cam and get serious force with. Both have their uses.

 

[jqavins]

It can run on about 5 volts and has enough travel. I wasn't looking carefully at all the specs. And I'm not saying it's a better choice than one of the all-in-one servomotor assemblies ("servo" is an adjective). I'm just saying one should generally avoid blanket statements like "solenoids are heavy" as reasons to pick this over that.

 

[OverTheTop]

Ok. I will agree with you on that. I usually pick on wide sweeping statements. As usual, part of the answer is "It depends."

Servo in the RC world venacular is a noun. In the electronics field a servomotor is a motor with a tachogenerator attached in my mind. I have examples of both on my desk presently.

 

[PayLoad]

In the above design, the solenoid takes no pressure or force from the flight, it simply releases the booster at a set time

 

[PayLoad]

Explosive Nylon Bolts, perhaps?

 

[3stoogesrocketry]

Built many moons ago I built a 4 inch rocket using 54mm side booster that fell off after burnout. I have no picture but the basic principle was using roller bearing slides out of a cabinet draw . The section mounted to the cabinet was secured to the rocket. The section on the draw to the side pod. Holding the pods on where metal " push locks " , I am not sure of the name of the locks. Basicly they pods are hanging from the rocket on the pad. At ignition the pods move forward .25 of a inch to push and unlock the slides. At burnout , gravity and drag slips them off the back of the rocket. Then the motor ejection pops the chute.

 

[PayLoad]

Built many moons ago I built a 4 inch rocket using 54mm side booster that fell off after burnout. I have no picture but the basic principle was using roller bearing slides out of a cabinet draw . The section mounted to the cabinet was secured to the rocket. The section on the draw to the side pod. Holding the pods on where metal " push locks " , I am not sure of the name of the locks. Basicly they pods are hanging from the rocket on the pad. At ignition the pods move forward .25 of a inch to push and unlock the slides. At burnout , gravity and drag slips them off the back of the rocket. Then the motor ejection pops the chute.

I've done that, called it the IKEA release.

Building same rocket (MoonShot) but I want NOTHING left on the sustainer (like 1/2 a drawer slide) Explosive bolts above worked, but far from "elegant".

Waiting for my solenoid magnets to show up so I can play with them.