Multiple Choice Dual Deployment

[ebruce1361]

First off, I haven't yet dabbled in true dual deployment as yet, but I do know my way around an Eggtimer Quark (I'm working on a home-built chute release with one). That being said, I do understand the basic principles of why one would want dual deployment and how it is commonly implemented.

So, here's my weird train of thought: Imagine parachutes deployed via altimeters just like regular dual deployment, but specific parameters have to be met before the altimeter selects WHICH parachute to deploy. For example, suppose you have a personal goal to fly your rocket over a mile high. If the rocket surpasses a mile, the ejection charge fires like normal at apogee, a little drogue pops out, and then at a specified altitude, a green main parachute deploys from one of two available bays. If the rocket did not pass a mile, the altimeter controlling the main parachutes deploys a red parachute instead from the other bay. This doesn't really have much practical use other than instant-gratification on confirmation of if-then conditions, but I wonder just how difficult something like this would be to implement. Is there a DD altimeter on the market that can already do this, or would I have to incorporate some kind of logic controller to compare the actual altitude data against target values and then interrupt the power to the charge well for the parachute NOT wanted?

 

[Buckeye]

Look at Raven. There are 4 output channels governed by logic that may work for you.

 

[Motocrossman24]

I don’t think there would be much issue doing this with the proper altimiter...you’ll obviously need something with 3+ channels, like a raven4, eggtimer proton, Marsa 33L etc...the biggest problem will be having 2 main chutes in 2 payload sections, and having a drogue chute...the most simple way I see this being done would be having a stuffer tube in the booster(drogue section) to isolate one of the colored main chutes from the drogue. At apogee your charge in the main body of the booster deploys the drogue, and then depending on your requirements, a second charge wither blows from the stuffer tube or the forward payload...the easiest way would just have 2 charges set in the regular payload section, one filled with the required main charge and packed with green chalk dust, and the other packed with red chalk dust...either way you go, your going to have to properly inhibit one of the charges so you don’t blow up your rocket

 

[Rocketjunkie]

Split payload bay in half lengthwise with a plate. Put a chute in each side. I'm not sure if a Raven can be programmed to fire 1 charge if above a mile and a different one below. (I know Adrian can do it.)

 

[Handeman]

What happens to the charge for the unused main? You still have a charge with ematch "active" when you or someone else walks up on the landed rocket?

 

[Steve Shannon]

What happens to the charge for the unused main? You still have a charge with ematch "active" when you or someone else walks up on the landed rocket?

Thank you for thinking about the safety aspect. Fancy should never take priority over safety.

 

[ebruce1361]

What happens to the charge for the unused main? You still have a charge with ematch "active" when you or someone else walks up on the landed rocket?

That is an excellent point. I was thinking of a setup where a pin is inserted into a socket to close the ematch circuit that would be pulled out at deployment. Each parachute would have one, so whichever main deploys, it automatically disarms the other whether or not the altimeter malfunctions and tries to deploy the other main. Still, that leaves the issue of an ematch loaded into a charge well that might have smoldering embers nearby.

Maybe another way around this is to have a CO2 system. A main altimeter opens a main solenoid to vent the CO2, but a secondary altimeter selects where the gas vents via a three-way valve. By default, the three-way is connected to the bay with the low altitude "fail" parachute. If the rocket achieves the desired altitude, the three-way valve is activated and the connection switches to the alternate bay with the "success" parachute. That way there isn't a live charge, armed or not, coming back down.

 

[GaryT]

This can be achieved with the New Missile Works Altimeter the RRC2L, It's to be released in May/June. However you'd have to have a dedicated RRC2L for each of those events.

https://www.facebook.com/groups/cjscjn/search/?query=RRC2L&epa=SEARCH_BOX

 

[boatgeek]

To address the safety issue, I'd rather do the multiple choice on the drogue. Green if over preset altitude, red if under. The other drogue charge fires when the main does so there's no live charges on the ground.