# First DD

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#### AfterBurners

##### Well-Known Member
I haven't built a DD rocket and would like to try my hand at it. I was leaning toward a kit or perhaps modify a kit such as WM Wild Child. I don't want to drop a lot of coin, just want to understand the concept behind building a DD rocket, so in the future I can apply these skills on other projects.

Any suggestions for kits or parts needed?

Thanks

Dan

#### GregGleason

I made a DD rocket from an Estes PSII Ascender (bought at Hobby Lobby with a 40% coupon). I did have to send off to Estes to by an additional airframe and coupler sections. So I think for the rocket it was under $50 for the kit and parts. I already had a PerfectFlite MAWD for the altimeter, so I had to figure out how to power it in the space available. I tried a DD on a Wild Child but the diameter was too small for my skills. Generally, the larger diameter makes the spacing issue easier. Here is my DD build: https://www.rocketryforum.com/showthread.php?134906-Estes-Ascender-Av-Bay-Addition Greg #### markkoelsch ##### Well-Known Member I would suggest a bit larger- easier for the first go around. Maybe a Wildman Junior of the budget allows. #### DavidMcCann ##### Well-Known Member cheap way, grab any LOC kit, the corresponding av-bay kit, an RRC2 and a 9 volt and have at it #### Zeus-cat ##### Well-Known Member I would suggest a bit larger- easier for the first go around. Maybe a Wildman Junior of the budget allows. I agree. Going small is hard with DD. Mark Koelsch had a good suggestion with LOC kits. Solid airframes and if you go 3 inches or larger plenty of room. #### MALBAR 70 ##### More Rockets Than Room TRF Supporter cheap way, grab any LOC kit, the corresponding av-bay kit, an RRC2 and a 9 volt and have at it +1. #### Tim51 ##### Well-Known Member cheap way, grab any LOC kit, the corresponding av-bay kit, an RRC2 and a 9 volt and have at it +1. Although in my case I used the PerfectFlite Stratologger CF, which I'd recommend. If you get the appropriate LOC EXL kit for your airframe, and follow the instructions for that and the SLCF, you can't really go wrong. As ever, if you're looking to understand the basic principles, before buying, Mark Canepa's Modern High Power Rocketry 2, although a little dated in some of its references, is still an excellent guide showing various examples of basic AV bay construction including the LOC 4" one (although it doesn't cover Head End Deployment or cable cutter/ chute release devices). #### rharshberger ##### Well-Known Member Any DD rocket 3" or less diameter I build with a completely removeable alt-bay because my hands are to big to fit down the tube. Some kits recommend glue one end of the alt bay coupler into the upper airframe and reaching down the tube to fiddle with the upper bulkhead can be tough. #### AfterBurners ##### Well-Known Member +1. Although in my case I used the PerfectFlite Stratologger CF, which I'd recommend. If you get the appropriate LOC EXL kit for your airframe, and follow the instructions for that and the SLCF, you can't really go wrong. As ever, if you're looking to understand the basic principles, before buying, Mark Canepa's Modern High Power Rocketry 2, although a little dated in some of its references, is still an excellent guide showing various examples of basic AV bay construction including the LOC 4" one (although it doesn't cover Head End Deployment or cable cutter/ chute release devices). Excellent! I read the book, but I may go back over that section on DD as a refresher. Just want to try something different for a change. It will be challenging for me as well. #### MikeyDSlagle ##### Well-Known Member Binder Design has two 3" birds with dual deploy - 100 bucks each. AFAIK, that's the best deal out there. Probably the most complete kits you will find also. And the dual deploy versions incrude the extra chutes and harnesses you will need, or at least the 4" versions do. Pretty much everything except the sled itself. They also have Doghouse products now so grab you the wiring kit and charge canisters while you're there. Only thing I don't like is the 2 part lids.. Mikey D #### tHoagland ##### Rocket Builder TRF Supporter The MadCow Torrent or DX3 are also good options for a first DD rocket. They both have 4 inch body tubes so the AV bay is large but with a 38mm motor mount, is still easy to fly on H/I motors. #### Binder Design ##### Well-Known Member Binder Design has two 3" birds with dual deploy - 100 bucks each. AFAIK, that's the best deal out there. Probably the most complete kits you will find also. And the dual deploy versions incrude the extra chutes and harnesses you will need, or at least the 4" versions do. Pretty much everything except the sled itself. They also have Doghouse products now so grab you the wiring kit and charge canisters while you're there. Only thing I don't like is the 2 part lids.. Mikey D Thanks for the mention and kind comments! Now that we are CNC, we could go to single bay caps with a step cut, but then we'd have to raise prices because we'd have to use the same premium plywood we use for fins. It's a balancing act to try to keep everyone happy. #### Coop ##### Well-Known Member I've got the Binder Excel DD in the build pile. I do like the way the kit is packaged--very nice. Looks like a solid design and an uncomplicated build. The av-bay, I think, is nice because it's very long as compared to others --two couplers with a wide switchband. One of these times, I've got to get back down into the lab and build it ... been spending too much time on the sewing machines of late. Heh. Later! --Coop #### markkoelsch ##### Well-Known Member Any DD rocket 3" or less diameter I build with a completely removeable alt-bay because my hands are to big to fit down the tube. Some kits recommend glue one end of the alt bay coupler into the upper airframe and reaching down the tube to fiddle with the upper bulkhead can be tough. I build all of mine to be removable. I too have large hands. I think a 54mm to 3 inch airframe is the right choice for a first dual deploy rocket. Larger and it takes more cash to fly, and smaller is not as easy to prep. You want something you can fly a bunch to practice dual deploy. My first dual deploy was a Loc lil Nuke that I extended. Flew it a bunch on g motors. #### cavecentral ##### Well-Known Member I like 4" diameter + for DD. 54mm is smallest I built DD so far. The 3D printed sleds really help getting everything to fit in a small space. #### Dave A ##### Lifetime Supporter TRF Lifetime Supporter My own 2 cents, (maybe someone else mentioned also) With the cost of decent altimeters at$40-50, for life of me I NEVER did a dual deploy without 2 alts. The labor to build the av bay is enough work and adding a 2nd alt is not much more.
Lots of folks will say that they never had a failure BUT one day you'll have a bad igniter or loose wire. Then your rocket becomes an accordion and your 1 altimeter is smashed.

#### KenRico

##### 'Just the Tip'
I agree. Going small is hard with DD. Mark Koelsch had a good suggestion with LOC kits. Solid airframes and if you go 3 inches or larger plenty of room.
Yes , going small is hard with a redundant altimeter setup , but not too bad if single with the Stratologger CF or a eGGtimer Quark . If you can put together a Quantum you don't even have to wire switch wires and connectors into the space . On a traditional redundant altimeter setup 3 and 4 inch is a big help.

One advantage on using what you have in hand is that if it doesn't work the fiberglass rocket can take a hard landing or if deployed on motor back up at speed will probably not hurt it .

If your Wild Child does not have the coupler glued into the upper payload tube it maybe a quick way to fly DD ..

Kenny

#### ttabbal

##### Well-Known Member
Thanks for the mention and kind comments! Now that we are CNC, we could go to single bay caps with a step cut, but then we'd have to raise prices because we'd have to use the same premium plywood we use for fins. It's a balancing act to try to keep everyone happy.
True. Perhaps offer an upgrade price to include the CNC lids? That comes with other problems like inventory control and possible mistakes though.

Redundant electronics doesn't have to be expensive. A Quark is \$20+an hour or so. Requires soldering, but that's a good skill and not hard to learn with a little practice. The harder part is getting dual altimeters with wiring etc, into the shorter AV bays that smaller kits come with. At about 3" diameter, it gets a lot easier. With a long bay you can fit dual altimeters into smaller tubes though.