G-Dual Deploy

[Handeman]

The charge holders on my bay are small bullet casings and weigh next to nothing. I thought about the tape/charge method but I am afraid of blowing a hole in my payload if the charge ends up packed next to the airframe wall. Has this ever happened to you?

I've used the duct tape as a holder many times and never had an issue with blowing holes in the sides. Duct tape will only work with black powder. The BP substitutes need to be contained much more to completely burn. Most of times I've heard of blowing holes in the BT have been with the BP substitutes because the containment causes a much higher pressure to build up and when it lets loose, its much higher force in a concentrated area.

No, that's not saying you can't blow a hole in a BT with BP, but with the small size of these rockets, the corresponding smaller charges shouldn't be an issue.

 

[Area66]

Duct tape !, I'm gone try it tomorrow, is it ok if I roll it around the electric match ( like the one who roll cigarettes ) and after fill with BP and then pinch the other side

 

[epickett]

I like your thread. I also didn't do electronics until my L1 rocket. I did one flight on a G64 with main at 400 ft. The flight only got to 468 ft, but the apogee and main worked right so my next flight was my L1 cert to 4,200 ft.

As you can see, I overbuilt this. I used 1/4" rods and thick end caps. The ID of the BT was 2" so the ID of the homemade coupler was about 1 7/8". One things that did work well was to put the tubes that the rods went through on opposite sides of the sled. That gave more room for the battery and altimeter.


Great thread!!!!

Interesting idea! Did you really gain that much space? It seems like you'd still be limited by the width of the sled and the rods to hold it...

Eldred

 

[epickett]

The power supply is two A23 12v batteries, a slight thinning of the 1/4 sled where they are mounted made for a snug fit. The battery contacts are 3/16" brass tube.

Question - why *two* 12V batteries? Isn't the altimeter supposed to work on ONE 9v?

Eldred

 

[H_Rocket]

I do G dual deploy in all of these

Small Endeavor 2.5" - ARTS (did not even stretch it)
Callisto 2.1" - MAWD
Legacy 1.5" - MAWD

 

[chadrog]

Question - why *two* 12V batteries? Isn't the altimeter supposed to work on ONE 9v?

Eldred

Two reasons - two batteries made for a nice snug fit in the bay, and I'm paranoid.

 

[epickett]

Two reasons - two batteries made for a nice snug fit in the bay, and I'm paranoid.

But you're not worried about over voltage? I'm not sure of the operating voltage range of these devices. I guess I should find my manual(s)...<g>

 

[chadrog]

But you're not worried about over voltage? I'm not sure of the operating voltage range of these devices. I guess I should find my manual(s)...<g>

The voltage remains 12, the batteries are in parallel. I don't remember the exact operating range of the unit, but I think the top end is either 14 or 15 - I did make sure 12 would be ok prior to finalizing the decision to use the A23's.

 

[Area66]

Ok I redo the altimeter I show and I put a switch

View attachment 140027
View attachment 140028
View attachment 140029


But don't expect to see switch for a long time, since I will use a 4 or 8 relay bluetooth system to arm the altimeter and shunt the BP charge, here at the Quebec section of the CAR we want to use altimeter with BP charge disable and shunted to make the thing more secure.

here the prototype, good for a 2.6" rocket and more , I already ask the guy in china to make it smaller

View attachment 140030

and here how I activate from my Galaxy Note II , I'm working on a real friendly interface , as I said it's 2013 , next altimeter bay will be plastic and aluminum

View attachment 140035

 

[epickett]

The voltage remains 12, the batteries are in parallel. I don't remember the exact operating range of the unit, but I think the top end is either 14 or 15 - I did make sure 12 would be ok prior to finalizing the decision to use the A23's.

Ok, I did some quick research. Here are voltages for some common electronics.
PerfectFlite
Stratologger: 4-16V
MAWD: 6-10V
Alt15K: 12V
MicroTimer:4.8-10.5V

Ozark Aerospace
ARTS: couldn't find
ARTS2: 9-15V

Featherweight Altimeters
Raven: 3.8-16V

Hope that helps anyone else.

Eldred

 

[gheem]

Hey Andrew, sorry you missed my first dual deploy of the "new" north coast Archer at NARAM. It was a great flight on a g40, and I have to say I am loving the smaller dual deploy for 2 reasons.

1. our main field is only to G motors
2. im am not L1....YET.....

The information on this thread is great, I have been reading all the cool ideas and trying to work out the best way for me to get in the game. My experience so far just working on this single project has really given me a lot on info and experience.

Anyway, the Archer kit is a 2.6 airframe and I just got a sled kit from Apogee to make life easier. I built the ejection charge cups from using epoxy clay and cutting a section of bass tubing about 1/2 inch diameter and an inch long, and shoving the tubing into the clay that was on the bulkhead. I static tested the system numerous times as I am using fffg bp substitute that I got from a local gun shop. I tested the charges vertically since one of the guys in our club is kinda a guru with small DD, and I just figured his advise was worth taking. At flight time I set the main to eject at 300 ft (low I know, but lots of trees and i built it solid, and the ground was a little soggy). The slight mistake I made was the motor ejection charge went off about the same time as the altimeter charge so the shock cord (steel wire attached to the motor mount bulkhead) got pulled out and the airframe seperated and free fell and a fin stuck in the mud, holding the airframe up off the mud, no damage! the forward section came down about 50 feet from the airframe, so glad I set the charge so low, or else I would have lost it to a thermal. otherwise the flight was perfect. So a small slap and a little quick repair and she will fly again, and the information and experience from that will just make the next flight better. I am having a lot of fun with DD, and I want to do more before I go for L1. Thanks again Andrew for all the advise, and to everyone else who has added to this thread. This humble BAR thanks you all!

here is a pic of a static main deploy test....it is rotated 90 deg...

 

[Handeman]

Interesting idea! Did you really gain that much space? It seems like you'd still be limited by the width of the sled and the rods to hold it...

Eldred

The rods do limit things, but if you put both rods on the same side, one side has limited height and width while the other has more height but is limited to the width between the rods. If one rod goes on each side of the sled, both sides have the same vertical height available and the width is only limited by one rod, not two.

 

[Handeman]

1. our main field is only to G motors
2. im am not L1....YET.....

Just wondering, is your field limited to FAA Class 1, or is it limited to G motors because of the safe distances? If it's limited to Class 1, you can fly H motors as Class 1, as long as the rocket and motor meet the requirements. If the limits are due to safe distances based on motor size, then its a G and not Class 1.

 

[gheem]

Just wondering, is your field limited to FAA Class 1, or is it limited to G motors because of the safe distances? If it's limited to Class 1, you can fly H motors as Class 1, as long as the rocket and motor meet the requirements. If the limits are due to safe distances based on motor size, then its a G and not Class 1.

Safe distances, limited to G.....we have a high power field, but as with most of the Midwest, it is a farm field, so we are limited on when we can fly there.

 

[epickett]

The rods do limit things, but if you put both rods on the same side, one side has limited height and width while the other has more height but is limited to the width between the rods. If one rod goes on each side of the sled, both sides have the same vertical height available and the width is only limited by one rod, not two.

Thanks for the explanation! I kept thinking, "It must be an advantage SOMEHOW", but couldn't picture WHY. I may just have to redo the sled in my Vulcanite. Currently it's a VERY tight fit to get everything in the bay. I have nothing to lose by trying your idea...

Eldred

 

[cgould]

Hey, All!

AKVP was frantically trying to reach me to chime in on the thread here. I've been on vacation, and will pipe in more when I am home.

I've done Dual Deploy on BT-60 rockets fro some time. The first flew on E-18 through F-35 (24mm) motors....typically on F-24's to heights of around 1000'

The second was more extensive, and primarily flew on F-40 through G-64 motors. This one has a dry weight of almost 1 LB, and is equipped with a keychain camera as well.

The next one is being built to be much lighter for 24mm reloads and all, and features very different construction techniques with the AV bay. Will be happy to share.

When going for my L1 Cert. many people asked me why I bothered with Dual Deploy. Answer: Because I've been doing i ta lot with the L0 rockets. Would make the L1 attempt too boring to not include dual deploy!

Will chime in within a day or so with pics / ideas!

 

[gdjsky01]

I was initially surprised by the tone of of the thread thinking a G dual deploy was odd. No one would bat an eyelash at a Dual Deploy H yet an H can be 1 (one!) lousy newton-second over a G and be called an 'H'. And some are! For example the 163H33 and the 168H54. I was thinking "A G76? That roughly 16 pounds of average thrust which at 5:1 = ~3 pound rocket. Whats the issue? You should achieve 2 pounds with motor and altimeter."

Okay okay but still well under 3 pounds right?



OTOH I love all the techniques in the thread! Thanks to all that posted (including the original)!!! I've not felt the need where I have been flying, to hit the dual deploy complexity button for G's. Tho I have felt the need to bring them down fast in the wind (which DD would solve, but so does a little bit of extra strength). If I did, I'd still use a cable cutter instead so I could use motor ejection at apogee. I think that is easier on the thinner tubing. Thoughts? That is what I am doing with a few of my rockets that have forward payload bays. Only my sleds are simpler because it's not traditional DD.

My 'Sled'

1) stuff some bubble wrap in payload bay
2) stuff the RRC2 altimeter in with battery secured and towards the top (RRC2's make this easy)
3) stuff some more bubble wrap in
4) put the nose cone on

:y::shock::wink:

at the pad...
1) get it all ready and vertical
2) take off the nose cone
3) connect the two wires to the RRC switch posts
4) put the nose cone back on
5) profit

The good thing about threads like this is they expose people to the idea that you can have all the complexity, challenge, and fun of the big boys and stay 'relatively' cheap.

For example: I have wanted to, for years, to build a composite two stage using simple 24mm reloads. I have not done it because I simply have not done it. But it should be doable for sure. Certainly 24mm E30s or 29mm econojet to econojet.

 

[chadrog]

For me it's about want, not need. I like flying a DD rocket at our small field on an F, fun.

 

[crossfire]

All I can say if anyone here is coming to LDRS 2014 at Bong you really need to learn DD recovery. Unless you like to swim or climb trees.

 

[AKVP]

Hello All-

Been a busy weekend. Wow I love all the replies. Jeff! Thanks for your post! your idea is something I was actually thinking about doing but chickened out! Maybe I will get some bubble wrap o Monday. Thanks to all who posted.

Like I mentioned in the first post: After going to many launches around Ohio and New York and Pennsylvania, I guess I just did not see many people doing dual deploy on lower impulse motors. I got the idea to try it out of necessity. Our club field is indeed beautiful, but it has many rocket eating trees and for those of you who went to NARAM 55, we now have a beautiful POND to look at in recovery area. I like to launch G motors but was tired of feeding the trees. Dual deploy offered some fun challenges. My original few posts with my attached photos show I like the "classic" sled look with everything mounted with 4/40 T-nuts, serviceable parts and an internal switch. But many who posted have offered some cool ideas. It is good to think outside the box but sometimes others can provide inspiration.

MTMA has a launch coming up this weekend and I hope to launch the new "G-super sport" on a G64 (It is the maroon and grey rocket with the black fins....photo on page one) I will let you know how it goes.

Also, look for some COOL posts and photos from CGould "rocket man" he has the market on tiny dual deploy in our club! He has some very cool and professional looking stuff.

Keep in touch everybody and thanks again!

 

[cerving]

MPR DD is loads of fun, and it's a good way to play around with electronics without spending a ton. I fly DD all the time with 24mm E/F's, if the field is relatively small and you have trees behind you it's a good way to get your rocket back. I have a BT55 scratch built that I use for testing Eggtimer software, it weighs about 3N (about 10.8 oz) with a 24/40 RMS motor and a slide-in sled, and is good for about 1400' or so on an F24. It's actually got a 29mm motor mount, but I haven't had a chance to try it on a G40... that will have to wait for my next trek out to Lucerne Valley, because OR says it will get to about 3,500'.

 

[AKVP]

cerving- would love to see photos of your sled and electronics bay on that BT55....wow. What altimeter do you use?

Would love to see photos from all of you....it helps with the ideas!!!

Thanks again!

 

[Area66]

..wow. What altimeter do you use?

Thanks again!

let me guess....an Eggtimer ....Cerving did I win one ?

 

[cerving]

Ding ding ding!

It's actually a bit of a squeeze in the BT55, but it fits, with two 150 mah LiPo's. The sled is pretty nasty looking cuz it's been through the wringer, I'll post a picture after I build a new one. It's basically a 1" x 4" basswood board that slides into the payload bay, with a bulkhead/coupler at the top. It just slides into the top section of the rocket until it butts up against a coupler, and another coupler is slid behind it and screwed into the payload tube.

let me guess....an Eggtimer ....Cerving did I win one ?

 

[cgould]

Here's a quick view of my first dual deploy AV bay.

This is built around a BT-60 Airframe.

Liftoff pic is the rocket that used this configuration the most. (Artemis / Pathfinder) 24 mm motor. The rocket pictured in my previous post (Artemis / Nala1) used this same AV bay for her first few flights, but the bay was replaced with one that was built to use a 7.5 volt LiPo battery. This was done because the Alkaline battery becomes very inefficient in cold weather, and the A23 barely had enough current to drive the electronics when the temperatures drop below 40 degrees. Nala1, BTW, uses 29mm motors.

Second picture is the older AV bay design opened up, exposing the Stratologger and A-23 battery.

Third picture is the AV bay with all the guts contained inside.

More to come...

 

[cgould]

Here are the parts of the Artemis / Pathfinder stack, my first BT-60 Dual Deploy.

More to come...

 

[Area66]

Nice rocket Cornelius

 

[AlfaBrewer]

1) stuff some bubble wrap in payload bay
2) stuff the RRC2 altimeter in with battery secured and towards the top (RRC2's make this easy)
3) stuff some more bubble wrap in

If you use bubble wrap, I'd advise finding some of the red/pink type as the normal bubble wrap can generate a surprising amount of static electricity.

 

[Area66]

If you use bubble wrap, I'd advise finding some of the red/pink type as the normal bubble wrap can generate a surprising amount of static electricity.

and fire the pyro .....

 

[TheAviator]

As requested by Andrew (AKVP), here are some pictures of the 2.6" DD rocket he posted up top. Flight is on a G64-10W to 1250'. It deployed a little early because the 10 second delay ended up more like 7.

The man and his rocket.


Liftoff!