Electronics Bay Deployment for Low Power (D-Engine) Rocket

All,
I have been building low/mid power rockets for about 18 months now and I would like to get a little more creative with my rockets. Before I get into the world of High-Power I would like to get my feet wet with the world of electronic bays and non-motor parachute deployment.

Here's what I'd like to do. Build a scratch build rocket with something like a BT-60 main body and have a booster engine for the main propulsion (D12-0) and then have an electronics bay with an altimeter connected to a ejection charge. So, I was thinking I would need to have a rocket with 3 elements:
- the bottom propulsion element that hold the main motor (D12-0). I assume I would need some venting in this area when the motor has completed its burn.
- the middle electronics bay with an altimeter and a vent hole
- the upper element that contains the ejection charge (wired to the altimeter) and the parachute.

This type of design is really only covered in the high-power discussions but I was wondering if anyone had any designs or advise/suggestions on how to construct this. Along with any ideas on a good smaller sized altimeter that support ejection charges.

Thanks,
jk

I'd suggest that you choose your altimeter first, as that could impact the size of the rocket that you design. E-matches are gettng hard to come by, so I would suggest selecting an altimeter that will fire the Quest Q2G2 low current igniters.

John

kachele said:

All,
I have been building low/mid power rockets for about 18 months now and I would like to get a little more creative with my rockets. Before I get into the world of High-Power I would like to get my feet wet with the world of electronic bays and non-motor parachute deployment.

Here's what I'd like to do. Build a scratch build rocket with something like a BT-60 main body and have a booster engine for the main propulsion (D12-0) and then have an electronics bay with an altimeter connected to a ejection charge. So, I was thinking I would need to have a rocket with 3 elements:
- the bottom propulsion element that hold the main motor (D12-0). I assume I would need some venting in this area when the motor has completed its burn.
- the middle electronics bay with an altimeter and a vent hole
- the upper element that contains the ejection charge (wired to the altimeter) and the parachute.

This type of design is really only covered in the high-power discussions but I was wondering if anyone had any designs or advise/suggestions on how to construct this. Along with any ideas on a good smaller sized altimeter that support ejection charges.

Thanks,
jk

Click to expand...

Here's an example of an Estes Ventris I setup as dual deploy. You could simplify to single deploy. For a simple electronic ejection you will just have the charge connected to your altimeter in the main BT. For the Ventris, my charges are on long leads and I put them behind the parachute so they are venting toward the open end of the tube. On my Blackhawk, I mounted Christmas bulb sockets in the Ebay bulkheads and plug the charges in directly so that the Apogee charge is actually on top of the recovery gear. I don't think it matters as long as you ground test and make sure you get good separation.

Blackhawk DD setup
Closeup of bulb sockets in E-bay end plates

The Christmas bulbs make good ejection charge igniters. They take a little bit of work but are cheap/free. Here is a link. Scroll down about a third of the way to see the Minibulb Igniter. I use a McDonalds soda straw hot glued to the prepared bulb. If using the bulb sockets, the green bases stay on the bulbs. If I mounting the bulbs on long leads, I remove the green base, solder the extensions to the bulb leads and then fold them upon each side of the bulb so when I glue on the straw the solder joints are sealed in hot glue between the straw and the bulb. Dump BP in the straw and then bend it over to compress the BP and tape it shut with masking tape.

Depending on whether you launch with a club and their rules, you can easily plug an Estes BP motor by picking out the clay cap and dumping the ejection charge. I pour in a little epoxy but I don't think it is necessary. Check with your club first.

kachele said:

All,
I have been building low/mid power rockets for about 18 months now and I would like to get a little more creative with my rockets. Before I get into the world of High-Power I would like to get my feet wet with the world of electronic bays and non-motor parachute deployment.

Here's what I'd like to do. Build a scratch build rocket with something like a BT-60 main body and have a booster engine for the main propulsion (D12-0) and then have an electronics bay with an altimeter connected to a ejection charge. So, I was thinking I would need to have a rocket with 3 elements:
- the bottom propulsion element that hold the main motor (D12-0). I assume I would need some venting in this area when the motor has completed its burn.
- the middle electronics bay with an altimeter and a vent hole
- the upper element that contains the ejection charge (wired to the altimeter) and the parachute.

This type of design is really only covered in the high-power discussions but I was wondering if anyone had any designs or advise/suggestions on how to construct this. Along with any ideas on a good smaller sized altimeter that support ejection charges.

Thanks,
jk

Click to expand...

Hey bud

You need to look into what the water rocket guys are doing. I don't know if you've see my thread
https://www.rocketryforum.com/showthread.php?38601-Never-Been-Done-In-Model-Rocketry-!-(-)
there's a video with chute deployment done by Air command Water rocketry, there guys got it going on with timers and timer controlled servos. I recently baught one from George Katz from Australia, a really cool and versitile piece of electronics, it can be set up in cascade, and has several trigger options, and can be set from 0-12 seconds of delay. It can also have altimeter integration, and be triggered with an internal G switch. Check it out, if you have any questions just let me know.

I would suggest you use a D11-p instead of the D12-0. Then you dont have to worry about that burn through! No vent hole needed.
D11s are also a bit cheaper too.

Alex

I just finished(minus paint) a vagabond and I think it would make a great lpr dd.I'm going to buy another and make a down scale of my AT Barracuda.What do you think

Aksrockets said:

I would suggest you use a D11-p instead of the D12-0. Then you dont have to worry about that burn through! No vent hole needed.
D11s are also a bit cheaper too.

Alex

Click to expand...

That's a great idea. Another option is D12-7 motors. Any rocket carrying an altimeter will almost certainly be to heavy for a D12-7 so your altimeter will be the main deployment mechanism with the D12-7 as a backup.

I tested dual deploy with mid power motors in heavy rockets before I used dual deploy in high power rockets.

I just purchased an Adept22. I thnk this would be a good choice for a BT-60 based rocket. The power and ejection charge connections are at the end of the altimeter which is great for a small diameter rocket. My Perfectflite altimeters have the connections on the side which makes it very difficult to get them in a small diameter rocket. The Adept22 is only $39.99 and it is dual deplo and records max altitude.

Kicking this thread back from the dead....

I am about to start a Vagabond build and the wife's STM-012 is done other than throwing the halves together with the coupler and paint/finish. I have started to mess around with building out a very lightweight AV bay in a BT-60 coupler that will be used/replicated for both. An Adept22 will be used and mounted on a balsa or thin fiberboard sled that will be friction fit in the coupler with balsa bulkheads. My question here is what is the lightest and smallest battery that I should consider for both powering the altimeter and for the pyro charge. Quest matches will be used to fire each .5g charge. In HPR I use lithium 9V batteries but there is no way I am throwing that much weight into an E/F powered rocket.

I have built a couple av bays with the BT60 coupler and a Perfectflite MAWD. I have successfully fired ematches with this battery https://en.wikipedia.org/wiki/A23_battery
and the MAWD.

Thanks, that looks like it may be just the ticket. At 12VDC and 55mAH, it should fire off two Quest Q2G2's with ease.