The Eggtimer EZ-DD Rocket/Altimeter, a Complete Dual-Deploy Package for $100

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FYI, it has come to our attention that some of the kits may have been sent out without the bag that contains the hardware and wiring bits for the AV bay. Let me know if you're missing them... we're going to be proactive and send out emails to each purchaser, however it won't be until Tuesday. Monday is tax day... enough said.
 
augendoc said:
My EZ-DD kit arrived yesterday. This kit is neat and robust. I had my electronics workbench already set up for another project so I knocked out the altimeter first. It’s a very simple build with all through-hole components except the voltage regulator, so I got a chance to use my reflow blower on that, just for fun. The instructions are very clear with good photographs. Cris includes several stopping points where you can test for correct assembly before proceeding deeper into the build. My sole 9V battery was petering out, but had enough power to test the electronics, which passed just fine. New 9V 6LR61 batteries on order from Amazon.

The through-hole components make this altimeter/controller very easy to build, even for a novice. Doubtless that's why Cris chose a through-hole over surface mount design.

My preference would be a LiPo battery but I can live with the 9V alkaline for now. Suggestions regarding a LiPo substitute would be appreciated.
Click to expand...
Darn near any 2S Lipo that will fit in the AV bay will work... you can probably get by with a really small one, maybe 200 mAH, and it will save you some weight over a 6LR61 9V battery.

I got a few flights with the EZ-DD in at ROC yesterday before the wind kicked in, went to about 2600' on a DMS H135W and 3800' on a DMS I205W. I like the AT DMS's in 29mm... quick and easy, and not much more than the RMS's with a lot less hassle. CTI 29's are nearly as easy too... if you can get them.
 
cerving said:
I got a few flights with the EZ-DD in at ROC yesterday before the wind kicked in, went to about 2600' on a DMS H135W and 3800' on a DMS I205W. I like the AT DMS's in 29mm... quick and easy, and not much more than the RMS's with a lot less hassle. CTI 29's are nearly as easy too... if you can get them.
Click to expand...
I'll second that. My regular BMS school rocket flies great on long 29mm motors like the H399 and H226.
 
What are you guys using for glue? I'm building one with yellow glue. I don't think I'll be loading motors that reverse the rotation of the earth.
 
When I get it I’m planning to use my regular West Systems.
Thinking about using the colliodal thickener to see if that makes a difference to my fillets
 
We built all of our prototypes using Bob Smith 5-minute epoxy. Titebond yellow would be fine too. West is probably overkill... but if you already have a ton of it laying around, better to use it than let it age out.
 
Welllll s#$@, there goes one of my rocket goals for 2024. "Don't buy any more rockets till I get through what I have". To good of a deal to pass up! Outstanding idea Chris. Order will be placed soon. Also, to BMS, great for participating in this endeavor. Good Job!!
 
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Unboxing!

Everything arrived in excellent condition. Very detailed packing list.
 

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Now someone’s got to come up with a great paint scheme. As Stickershock23 says, “never fly naked.” Chris Michielssen did a build here with red NC, white BT and blue fins, with silver stars on the NC and BT. I’m thinking maybe black or dark yellow NC with a leopard spot wrap to hide all the holes for the av-bay.
 
augendoc said:
Now someone’s got to come up with a great paint scheme. As Stickershock23 says, “never fly naked.” Chris Michielssen did a build here with red NC, white BT and blue fins, with silver stars on the NC and BT. I’m thinking maybe black or dark yellow NC with a leopard spot wrap to hide all the holes for the av-bay.
Click to expand...
I like @cerving's logo: white with red fins, freckles and a pair of googly eyes and a smirk of a smile :)

9622.jpg

-- kjh
 
Mward said:
I suggest color and 2-sided if you're printing out the instructions.
Click to expand...
Yes... BUT 1st thing to do then is number the pages.!.!.! ASAP.

I do all the Eggtimer instructions this way. Hold them together with a binder clip for storage. When building flip thru pages and they lay flat. [ Then when they are inevitably knocked off the bench, they can be put back in order. ]
 
My bag of missing bits shower up yesterday so today I have my altimeter bay complete! I glued the internal coupler rings slightly too far in to allow the bulkheads to clamp the coupler properly, so removed the washers on the main side and sanded about 0.5mm off the sled to get everything to fit/clamp nicely.

If I was to build a second one I'd make sure the rings in the coupler are a hair less than ¼" from the ends, rather than the hair more that I built. I think the error came from placing the ruler at exactly ¼" making with a pencil at an angle (trying to get inside the tube) which was probably close to 7mm (9/32") as a result, and then following the instructions without thinking and gluing the ring just under the mark I made, so ended up about 1mm too far in on both sides.

Other than that one easily fixed issue, everything went together really well! I had to do a test fit in the rocket as well of course, however I hadn't actually started on it yet so everything is literally just friction fitted together. Sitting beside my Big Daddy for scale.
 

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miket6000 said:
My bag of missing bits shower up yesterday so today I have my altimeter bay complete! I glued the internal coupler rings slightly too far in to allow the bulkheads to clamp the coupler properly, so removed the washers on the main side and sanded about 0.5mm off the sled to get everything to fit/clamp nicely.

If I was to build a second one I'd make sure the rings in the coupler are a hair less than ¼" from the ends, rather than the hair more that I built. I think the error came from placing the ruler at exactly ¼" making with a pencil at an angle (trying to get inside the tube) which was probably close to 7mm (9/32") as a result, and then following the instructions without thinking and gluing the ring just under the mark I made, so ended up about 1mm too far in on both sides.

Other than that one easily fixed issue, everything went together really well! I had to do a test fit in the rocket as well of course, however I hadn't actually started on it yet so everything is literally just friction fitted together. Sitting beside my Big Daddy for scale.
Click to expand...
I used a compass to draw my line for the coupler inset, then spread a ring of epoxy just beyond but up to the line. Then inserted the ring and turned the coupler ring-side-down over the plywood bulkhead and pushed the ring down tightly against the bulkhead with a dowel through the upper end. Then flipped and repeated. Then set the coupler on its side until the epoxy cured so the rings wouldnt get any gravity movement..

I used BSI 30 minute epoxy. The rings sit dead flush and I adjusted the other sled parts to fit.
 
augendoc said:
I used a compass to draw my line for the coupler inset, then spread a ring of epoxy just beyond but up to the line. Then inserted the ring and turned the coupler ring-side-down over the plywood bulkhead and pushed the ring down tightly against the bulkhead with a dowel through the upper end. Then flipped and repeated. Then set the coupler on its side until the epoxy cured so the rings wouldnt get any gravity movement..

I used BSI 30 minute epoxy. The rings sit dead flush and I adjusted the other sled parts to fit
Click to expand...
I considered using the bulk head as a spacer which would have prevented my issue. I didn't because I was impatient and the paint on the bulkheads was wet at the time. A lesson learnt for sure.
 
Hmmm... The Eggtimer EZ-DD OpenRocket file (https://eggtimerrocketry.com/wp-content/uploads/2024/04/EZ-DD_Open_Rocket.zip) has a 30" Main and a 12" drogue.

The kit came with a 24" nylon chute. Luckily I'll be flying this at MDRA and Performance Hobbies is scheduled to be there.

Any recommendations on a drogue/main chute selection? The 24 inch chute and no drogue performs well in simulation.

Does anyone make a kelvar drogue?

- Matt
 
Mward said:
Hmmm... The Eggtimer EZ-DD OpenRocket file (https://eggtimerrocketry.com/wp-content/uploads/2024/04/EZ-DD_Open_Rocket.zip) has a 30" Main and a 12" drogue.

The kit came with a 24" nylon chute. Luckily I'll be flying this at MDRA and Performance Hobbies is scheduled to be there.

Any recommendations on a drogue/main chute selection? The 24 inch chute and no drogue performs well in simulation.

Does anyone make a kelvar drogue?

- Matt
Click to expand...
I fly my similar stretched Leviathan with a 6’ streamer as a “drogue” and it’s worked very well. Probably rig my EZ-DD the same way - all of the fields were I regularly launch are fairly soft grass or crop covered ag fields here in Ohio and western PA so visibility and quick descents (gotta stay out of the corn or beans!) are bigger factors than damage from hard ground.
 

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