Gemini DC Mods

[wickball]

Ok guys, I bought a Gemini DC at half off close out price. Just got done reading the TRF search archives and EMRR reviews. I'm aware of the need to beef up the side tubes for heat protection, any other tips to make it eject more reliably would be greatly appreciated!
Thanks ahead of time!

wick

 

[wwattles]

I had ejection problems with the Estes paper-fold parachute mount getting in the way. The obvious solution would be to glue a kevlar tether to the inside of the outboard tubes' nose cones, then attach the chute cords to those before gluing on those nose cones. And believe me, in those little tubes, even the extra thickness of folded paper can definitely get in the way!

WW

 

[jerryb]

funny this thread should come up,

after the launch today, I was wiping the birds down, and noticed that both side pods on my Gemini were bubbling and about to burn through... looks like I'll be having to add something over the tubes to prevent the burnthrough...

oh well.. it sure flies great..but is a royal pain to pack

later
Jerryb

 

[LtSharpe]

Well I haven't had any problems with mine in 6 flights, except the chutes tend to twist together in descent which sometimes makes it lawn dart. Other than that it's pretty spiffy. Mine is a yellow and black paint scheme.

 

[dcom2]

I am relatively new to rocket building/flying. I have a question regarding the Gemini DC:

I followed the directions and stuffed 2 sheets of wadding into side chutes, then the parachutes (as loosely as possible -- still pretty tight), then 2 more sheets of wadding.

The question is what causes the chute to get ejected?

I remember attaching the side tube to the main tube with a little hollow connector, so I am thinking maybe the pressure shoots through there and burns up the top wadding... but then why is there more wadding on the bottom?

I appreciate anyones help with this... I am baffled.

Thanks, Clay

 

[jammer]

I went ahead and superglued some aluminium foil to the inside of the tubes opposite the exhaust when I built it. So far this has solved the problem of burning through the tube.

It's flown a couple of times and other than the parachutes semi-tangling, it's a great rocket.

Doug

 

[wickball]

dcom2, the extra wadding in the bottom is to prevent from parachutes from falling out while the motor is burning and the rocket is still accelerating. The connector tubes allow the ejection gasses to pass through to the area where the chutes are stored, onto the upper sheets of wadding, pushing the chutes out the bottom. hope this helps. i have flown mine once, both chutes ejected ok but only one unfolded.

wick

 

[BrnAgainRoc]

i went extreme with mine guys. My newly built DC is a 24mm MMT with clustered 18mm's on the sizes. I took epoxie and covered the inside walls with it smoothly to give it a stronger coat so it would hold up to a c engine . Its turned out quite nicely.It pops a main chute out of the main body tube. Its gonna be a cool flight

 

[teflonrocketry1]

I just finished building mine Sunday. I built it stock with a few minor mods. I put in a balsa bulkhead and made the forward end into a vented payload bay to hold an altimeter to confirm the computer simulations I made for a rocket with side pods.

Bruce S. Levison, NAR #69055

 

[Planet Andy]

I glued in BT sleeves to seal the side pods off and eject one chute out of the main tube. It flies great, better than I expected but so far has burned through two chutes in two flights on 4 pieces of wadding. Next time I'll try more wadding and wrap the chute in a sheet or two of it. Landing without the chute caused no damage on either flight so I'm pretty impressed with the strength of it also!

https://www.planetandy.com/gemdc.html

Andy

 

[RocketboyG80]

Originally posted by Badboy1982
i went extreme with mine guys. My newly built DC is a 24mm MMT with clustered 18mm's on the sizes. I took epoxie and covered the inside walls with it smoothly to give it a stronger coat so it would hold up to a c engine . Its turned out quite nicely.It pops a main chute out of the main body tube. Its gonna be a cool flight

The Gemini is one of those kits that very few people build stock. I did the same mod to mine (why put parachutes in two perfectly good motor tubes?) along with adding a 6" payload tube and noseweight for stability. And now that I think about it I also scaled the fin size down some for increased performance and put 3/16" lugs on it. It flew great on a central C11-7 with outboard C6's. Very high and fast flight, and I manged to recover it nearby as I only put a little Mylar streamer in it. Can't wait to up th ante with a central D12 or E9.

 

[thehebrewhammer]

I have been working on my modified Gemini DC that has functional SRBs that fall away when they burn out.
See the photo.

Hammer

 

[thehebrewhammer]

Here is another.

 

[m85476585]

You don't have to use wadding for the second 2 sheets. It can be anything- paper towels, Kleenex, paper, whatever will hold the parachutes in securely enough during boost.

What about motors only in the pods and chute ejection about the rear center tube (where the motor mount would be)?

 

[BrnAgainRoc]

Originally posted by m85476585
What about motors only in the pods and chute ejection about the rear center tube (where the motor mount would be)?

I think stability would become an issue so if this is your route id check cg and add nosewight if you must. Whats bad about the 3 motor cluster is when one of the pod motors dont ignite. It causes the SS1 incident all over again with spirals and loopty loops.