Estes Astron Elliptic II (Dual Deploy) Build

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Leo

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Something I've always been itching to build. A BT-20 based 2 stage mini "A" engine powered rocket with a dual deploy recovery system :)

The Estes Astron Elliptic II came as a logical choice for this project.

All the parts from the kit laid out:


I'll be using my own altimeter.

I'm still trying to figure out the best solution on how to build and setup the e-bay for the altimeter. It will be small thus making things a bit tricky.
 

KillPact

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Interesting, what inspired you to try this? :) And do post pics when you are either finished or building.
 

Leo

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Everyone is going big and bigger with dual deploy recovery rockets. I want to go the other direction :)

This will be a build thread.
 

mwtoelle

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Who makes an altimeter small enough to fit into a BT-20? I think a better choice for dual deploy would the three stage Mini Commanche-3. Three 13mm A motors should really get up there.
 

Leo

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Who makes an altimeter small enough to fit into a BT-20? I think a better choice for dual deploy would the three stage Mini Commanche-3. Three 13mm A motors should really get up there.
Built my own. See sig.

I think a better choice for dual deploy would the three stage Mini Commanche-3. Three 13mm A motors should really get up there.
Too heavy and I'm not looking for altitude.
 

Leo

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First up was to put the engine mount together.

All the parts laid out:


Here both mounts finished, built according to instructions:


I selected to install the engine mounts before applying the fins to the body tubes.
(I forgot to make pictures before putting on the fins)


Then I installed the fins on the booster first:


That made it much much easier to install the fins on the sustainer:


Now all the rocket needs is 2 more fillets on the fins and the launch lug. When all is dry I'll give the fins 3 coats of sanding sealer.


This is pretty much the finished model according to the instructions. Now I have to work out how I'm going to add an e-bay section to integrate the altimeter.
 

mwtoelle

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I would put the e-bay just above the tube joint on the sustainer. Because of the size of your altimeter, I would put a coupler on each end of the bay. Just my :2:.
 

Leo

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Thanks for the suggestion Mike.

I've applied the sanding sealer and sanded the model to a smooth finish.
It's ready for the first coat of primer.

 

nute

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Who makes an altimeter small enough to fit into a BT-20? I think a better choice for dual deploy would the three stage Mini Commanche-3. Three 13mm A motors should really get up there.
I just flew mine the other day, and it's really not that impressive of a flier.
the first stage is a bit underpowered to get the whole thing up fast enough. mine was a bit heavy, and it arced over and when the third stage fired it was close to horizontal!
 

Leo

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I just flew mine the other day, and it's really not that impressive of a flier.
the first stage is a bit underpowered to get the whole thing up fast enough. mine was a bit heavy, and it arced over and when the third stage fired it was close to horizontal!
It will be a challenge, no doubt.

I will be replacing the heavy plastic nose cone with a balsa version and I'll be using a longer launch rod.
 

nute

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It will be a challenge, no doubt.

I will be replacing the heavy plastic nose cone with a balsa version and I'll be using a longer launch rod.
I was talking about my mini Comanche 3 actually...
My astron elliptic flies great as a single or double stage!!
My most flown rocket
Those modifications will help with added weight though.
 

Leo

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YIKES! I started this thread in 2012...

No matter, the Astron Elliptic II is finished...



almost.....

Now to complete the tiny e-bay :)
 

Leo

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I just finished building the altimeter that I will be using with the Astron Elliptic:

 

Leo

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Done.. here is the dual deploy e-bay with the altimeter tucked in place:



And here the Estes Astron Elliptic II with e-bay:

 

Leo

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... and here is the maiden flight of my Estes Astron Elliptic II. My Gopro doesn't have a zoom lens so the rocket is hard to make out in the video.

(Needs to be watched in full screen)
 
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ipostelnik

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Do you mind sharing more pictures of the E-bay? How did you house the separation charges?
 

Boosterdude

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I was fortunate to see this flight in person and it worked perfectly. Dual deploy in a rocket this size is one of the neatest things Ive seen in along time. Congratulations Leo, job very well done!!!
 

Leo

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Do you mind sharing more pictures of the E-bay? How did you house the separation charges?
I use a small centrifuge canister with inserted e-match and flash cotton on both ends for the ejection:

 

Hnefi

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Man, this was a great read. I flew an Elliptic II for at least 8 flights before the sustainer finally burned a hole right through the booster. Great introductory two stage bird, my third kit ever I think.

But Nothing like this though. I can appreciate the use of electronics in such a small package too. I've done a few projects on Arduinos and this is great stuff.
 

Leo

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If all goes well this year, I'll be flying my dual deploy Elliptic II using electronic sustainer ignition instead of motor stage ignition.
My main concern will be adequate thrust with the booster engine as I'm pushing the limits with thrust to weight ratio.
 

cbwho

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In regards to staging rockets, has someone built a D, then C then mini engine. 3 stager?
 
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