Shock cord / estes dent problem with HJ K1919 clone

[billeblurzz]

I have an Honest John K1919 clone flying on a C6-3 that the balsa nose cone severly impacts the body tube or fins causing much damage to either one on ejection. I have tried increasing the shock cord length to now at 5 ft. and still have impact. This seems excessive for a rocket that only measures approx. 18" in length. It is one of the Thrustline clones (excellent kit by the way). John, or anyone else, do you have any advice? I modeled the spin rockets and added to the nose cone. Of course, the last impact wiped out one of the spin rockets and severely gashed the balsa cone. I thought that increasing shock cord length would cure this. The time delay seems about right for the weight of the rocket. I do have about 2 oz. added weight in metal washers behind the nose and held with glue and the shock cord eyebolt. Any suggestions? thankx

 

[llickteig1]

I have for about a year changed the order of the parts on the shock cord. Have experienced less banging since. I use this mostly for MPR and HPR, but no reason it won't work for ModRocs.

Put the airframe on one end of the shock cord and the parachute on the other. The nosecone then goes about 1/3 down from the parachute. This configuration looks cool coming down and seems to keep the parts apart.

Give it a try, --Lance.

P.S. I am also a big proponent on NO ELASTIC. Replace with long-ish kevlar line. No burn-through problems that way.

 

[flying_silverad]

Originally posted by billEblurzz
I have an Honest John K1919 clone flying on a C6-3 that the balsa nose cone ............. increasing shock cord length would cure this. The time delay seems about right for the weight of the rocket. I do have about 2 oz. added weight in metal washers behind the nose and held with glue and the shock cord eyebolt. Any suggestions? thankx

I agree with Lance. I also think you should probably look at extending the delay. I found that anything less than 5 seconds seems to get inot an overspeed situation before apogee.

If, you still don't have any luck, let me know. I'll be happy to make it right.


As a side note, I have stopped selling this rocket because of the nose cone. Great Cone, it's just way to expensive.

 

[Austin]

Something else to consider that really will catch some attention is dual parachutes...one for the nosecone and one for the bodytube. This way both items stay away from eachother at ejection, which pretty much eliminates the chance of damage.

Carl

 

[loopy]

I'm also just wondering where the parachute is on the shock cord. I tend to put my parachutes fairly close to the nose cone, and this seems to help as well. Maybe I'm way off base, and I've just been lucky though.

Loopy

 

[flying_silverad]

Originally posted by Loopy
I'm also just wondering where the parachute is on the shock cord. I tend to put my parachutes fairly close to the nose cone, and this seems to help as well. Maybe I'm way off base, and I've just been lucky though.

Loopy

If you have a 5 foot shock cord, I would think you could get away with having it 1/3rd of the way back from the nose cone.