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Estes Cosmic Cobra Build (This time it's personal)

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RocketsNorth

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OK, so a little history on this one.
Last year, when I was just introducing my boy to the hobby we ordered the Cobra because he thought it looks cool and I kinda thought the helicopter recovery would be interesting.
Because it's an E2X (Easy to Assemble) I let him do most of the build, and I think he made a pretty good job all in all.
So one cold day in February we took the Cobra and a couple of other rockets out for a launch. The first two went off beautifully, the Cobra which had been sitting in the cold for about half an hour was our last launch and long story short, the nose cone never popped and the thing did a burning lawn dart onto the frozen ground and crushed the BT.
Fast forward a few months after an email to Estes CS and a replacement kit which sat on the shelf I decided to open the kit and put this one together and see if we can successful flight.
 

RocketsNorth

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So the build is easy, less than and hour to complete and most of that was waiting for the plastic cement to set....
 

RocketsNorth

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The only noteworthy alteration made was to substitute the standard Estes paper shock cord holder that gets glued to the inside of the BT with a loop of 16lb test Kevlar thread that was glued between motor mount and the BT. The shock cord was then fastened through the Kevlar loop.

The blade hub was cemented to the base of the NC and the blades were inserted per the directions

 

RocketsNorth

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Finally the chute was tied to the free end of the shck cord rolled and the blades folded and the NC Assembly mounted and the bird is ready to fly and hopefully this time seperate and land safely:w:



I'll post a launch report
 

The EGE

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It's very hard to keep a chute from frying in the Cosmic Cobra. I just took mine out and the booster glides safely down.
 

RocketsNorth

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It's very hard to keep a chute from frying in the Cosmic Cobra. I just took mine out and the booster glides safely down.
Interesting. I suspected the failure was due either to the rocket laying in the cold for half an hour or that we had not gotten the shock cord anchor clear of blade when we glued it into the BT.......

Thx for the info!
Appreciated
 

The EGE

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Interesting. I suspected the failure was due either to the rocket laying in the cold for half an hour or that we had not gotten the shock cord anchor clear of blade when we glued it into the BT.......

Thx for the info!
Appreciated
Well, there's two ways to pack the chute in the CC. If you pack it between the blades, you get a no-deploy. If you pack it under the blades, it fries.

Fortunately, the booster glides back rather efficiently - barely faster than some gliders - and in six flights It's never been damaged.
 

gpoehlein

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Actually, I've flown the CC several times without a mishap. I find that the trick is to pack the chute carefully between the blades - but as one long thin spike. Just make sure it isn't pushing the blades too hard against the sides of the BT.

I can tell you that the CC is always a crowd pleaser. :p
 

NjCo

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A word of warning when cementing the blade ring onto the nose cone. If you follow the instructions and use plastic cement the joint may fail and you'll have a not nearly as interesting three piece recovery. Luckily I found this out while prepping the rocket for flight and not while it was in flight. The pieces came apart in my hand with only a little pressure. I then easily chipped off the remaining glue with my fingernail and was left with two like new parts (the ring and the nosecone). I then decided to go with the heavy artillery so to speak and grabbed my bottle of ProWeld for a perfect bond.

As for the chute, packing it in the blades is the way to go. Spike the chute then fold it lengthwise onto itself several times till you have a column about 1" wide. Then fold the tip of the chute down so the length of the chute is the same as the blades. Then wrap the shroud lines around the chute. This has worked well for me every time.
 

mjennings

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I used to do something similar to Greg with an older estes model similar to the Cosmic Cobra and it worked well
 

RocketsNorth

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Very good advice for packing the chute. If memory serves I packed the chute in the standard way described in the instructions.....

I will try the long narrow method.
 

RocketsNorth

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A word of warning when cementing the blade ring onto the nose cone. If you follow the instructions and use plastic cement the joint may fail and you'll have a not nearly as interesting three piece recovery. Luckily I found this out while prepping the rocket for flight and not while it was in flight. The pieces came apart in my hand with only a little pressure. I then easily chipped off the remaining glue with my fingernail and was left with two like new parts (the ring and the nosecone). I then decided to go with the heavy artillery so to speak and grabbed my bottle of ProWeld for a perfect bond.
Thx, I'll check it over before I fly it.....
 

TheAviator

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An interesting way to fly the CC so that you don't have to worry about the parachute is to run the shock cord to the tip of the nose cone, drill a hole in the cone, then tie it to the tip. For those who care, this does make the rocket contest Heli Duration legal.
 

RocketsNorth

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An interesting way to fly the CC so that you don't have to worry about the parachute is to run the shock cord to the tip of the nose cone, drill a hole in the cone, then tie it to the tip. For those who care, this does make the rocket contest Heli Duration legal.
Thanks Aviator! That is a Really interesting suggestion. I don't think I'll try it immediately, but after a few successful fights, it might be worth a try.
 

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