large model recovery

(Now you've done it.)

I use sewing elastic on MODELS and LARGE MODELS, but I am very careful to keep the direct ejection charge blast away from it. I like "shock absorption" in my shock cords to reduce stresses at deployment. I've used elastic in my heaviest MODELS after seeing it in a commercial MPR/HPR kit (can't remember which one, but it was about one inch wide black elastic).

I usually mount it above an ejection baffled motor by threading it through a tube coupler (or split body tube piece) and gluing that down inside the airframe as far aft as possible. The chute and remaining harness are all forward of the mount point and eject out of a clear tube.

For non-baffled motors, I use Kevlar cord inside the airframe and tie that to some elastic which goes to the NC/payload, ala Quest. Coat all recovery harness knots with glue to prevent slipping. I try to get at least twice the rocket's OAL in shock cord. I seriously believe that heat issues and too short shock cords are what have given elastic a bad rep. However...

My L1 bird is actually a LMR with rear separation and I am using tubular nylon attached to an eye bolt in a structural bulkhead for the recovery harness. This rocket is built much stronger than my largest models and can take (I hope) the inelastic (sic) deployment shock of the TN. I'm not sure elastic or bungie wouldn't suffice for a normal flight; this is just a worst case design.

What type of elastic is used to attach the chute to the rocket on larger models >1lb? Where does it attach? For the smaller ones I have been using sewing elastic and it has worked fine for the smaller ones but not shure about this larger one.

Mile High Rockets

sells Kevlar Elastic shock cord. It combines the best features of both Kevlar and elastic. Unlike most Kevlar cords, this stuff will stretch up to twice its length to reduce the deployment jerk. Unlike most elastic, their elastic is encased in a Kevlar braid that provides fire resistance as well as >100 lb strength.

The owner of Mile High is very helpful and friendly and the service is always fast.

Best of all, they do not charge for shipping and handling.

-- Bob Cox No financial interest, just a VERY pleased customer.

Hmm...

Saw the subject line and thought it was about Anna Nicole Smith's recent weight loss...

David Erbas-White

Mike wrote: