I built a Quest Zenith II not too long ago. Flew it the first and last times at NAR this year. It was a bit windy for a fine-flying two stager like this one, and on the third flight, it sailed off to Never Land. After I built it, I had essentially the same idea stated by BobH48, but with a twist. I did put a really tight fit of tape on the nosecone shoulder (and would have added a strip around the outside of the join if I'd added a payload). My thought was to fasten a line in a small loop to the inside of the nose, using epoxy. That way I could do any of the following:
(1.) Fly the model with an empty payload section, just using a taped shoulder to hold the nosecone on and hooking the shock cord via swivel hook to the loop at the bottom of the payload section. The nose is light, so tape around the outside of the seam isn't needed (as long as the shoulder is tight), but it could be added easily enough.
(2.) Fly the model with no payload section, hooking the shock cord to the added loop on the nosecone. The shoulder would need to be adjusted to mere normal tightness in this case, lest the chute not deploy.
(3.) [The more innovative option] Fly the model with a payload. Run a piece of nylon or kevlar twine from the added nose cone loop down through the payload section and out the bottom, pulling it taut and securing it there with a knot, perhaps tying a small piece of dowel in the knot to make it less likely to pull through. It could be tied around the loop at the bottom of the payload section as an alternative. The Zenith II's payload section is dark, and a cord (especially a dark colored one) wouldn't show much. The hole (for the added twine) at the bottom of the payload section would be placed to the side rather than the center, so with the nosecone turned to place the added loop on the same side, the cord securing the nosecone would run down the inside wall of the payload section, leaving most of the space unobstructed. Of course the shock cord would be attached to the bottom of the paylad section as before, and tape on the outside of the nose-payload join would be optional.
Hmmm. Had another thought. If the added twine had a tied loop in one end and a swivel hook type attachment on the other then the attachment would be very easy. Pass the tied loop through the bottom of the payload section, then pull the payload section's loop through it, fastening on the shock cord. Then the other end of the twine could just be clipped to the added loop on the nose. Better still, the clip on the shock cord could be fastened to both the added twine's loop and the playload section's loop. This doesn't have to be all
that taut - just enough that the nosecone's shoulder won't clear the tube if it is pulled upward. As you can see, there are lots of ways to approach this, and brainstorming them is fun.
Just my 2¢ worth.
My next Zenith II will receive this treatment.