Can my Comanche-3 be fixed?
 

I just found the forum recently and have been finding lots of great info. Like others, I built and flew rockets as a kid and then got back into it as my kids grew old enough. I built a Comanche-3 for a Boy Scout launch in the CA desert 2 years ago. I love the rocket, but like others have experienced that second stage is hard to find. The first year I flew it 3 times. The first time no one saw where the second stage went, so it flew once as a 3 stager and twice as a 2 stager. The last flight I had the booster stage on too tight, and it never separated. It got burnt to a crisp. The next morning one of the adults went for a morning walk in the desert and found my second stage.

For the next year's event I built a new first stage and assigned several boys just to watch the second stage. We had little trouble finding it this time, and I did 3 launches as a 3-stager. But, on a couple of the launches both years fins broke off on landing and had to be repaired. The last launch last year I did the same thing on the second stage and burnt it to a crisp (you think I'd laern better :D ). The top stage landed hard and did a number to one of the fins. I had already re-glued it a few times, and this time it tore through the body and left a sizeable hole.

This year's event is coming up and I am starting to get ready. I think I will just fly the Comanche as a 2-stager this year (I am getting tired of the hunt for the second stage and the long walks to get the top stage). But I neet to fix the broken fin. Is it fixable? Any tips? Or do I need to rebuild the bottom end? I'll try to post some photos momentarily.

Here are a couple of photos.

That thing is toast.
It would be less trouble to build an entirely new one than hacking the motor mount and fins off the bottom of the main body and coupling a new section in.
Besides that, if you fixed the beat up one it would take as much time and almost as much money as buying all the needed parts through Semroc to clone another one; even if you did that, you would still have a beat-up Comanche-3 instead of a decent new one.

It SERIOUSLY needs to RIDE THE BOOT right into the trash can.

Upper stage can easily be repaired. One method is to simply re-glue using the same glue used originally (yellow wood glue, I hope) and then, after it is dry, apply a little reinforcement by applying a "doubler" over the fin/tube joints. This can be as simple as paper wet with yellow glue or paper wet with epoxy. No need to make it super heavy. you just want it to be at least as strong as the original body tube to fin joint.

the booster that was roasted needs to be rebuilt.

Tape the motors properly. See the Estes "Classic Collection" section on multi-stagers.

I say build a new one and salvage whatever you can from this one for spare parts bin. That is way too much work for something that will always look like crap from this point forward.

Rebuildable? Yes. Worth it? No way!

Thanks for all the quick replies! I'm tempted to just do what Fred recommended and patch it up. I agree with ghrocketman and STRman that it would not look good, but there is a part of me that would like to see how long I can keep it flying no matter how ugly it gets.

Fred, for the repair you mentioned that you hope I used yellow wood glue originally. I did, but that fin was repaired at least once with CA. Does that change things?

I also thought about just making it a Comanche-2 with the first and upper stage. If I cut off the bottom of the upper stage, glued in a new motor mount and glued on new fins, do you think the shorter 2-stage version would be stable?

CA is not my favortie (putting it mildly) for wood/cardboard and rockets. It soaks into the materials and makes them hard and brittle, helping them snap off later.

Use 5 minute epoxy since that will stick to the CA impregnated parts as well as any clean parts.

And fly it until it can't fly no more....:D

This is a fairly common failure in stagers. It's really not about the booster being too tight. It has more to do with not having positive motor retention in the booster. When the next stage lights, the booster motor slides out the back while the booster section stays attached getting fried in the process.

If you have positive motor retention, the booster has to separate with the booster motor. It's fairly straight forward to add to 1st stage boosters. But adding it to the middle boosters is kinda tricky.

I used a tape thrust ring (three wraps of ¼" masking tape) to implement mine. Normally, these are applied at the aft end of the motor. But in this case, it's applied near the forward end of the 2nd stage motor, just below the tape which joins the 2nd stage motor to the sustainer motor.

To accomodate this, I recessed the motor tube in the 2nd stage. I had to shorten it about a ½" as I recall. The tape thrust ring keeps the 2nd stage motor from exiting aft. Thus at staging, when the motors separate, the stages must separate, too.

I thought I had some drawings up on the web, but danged if I can find them right now. So I hope my text is descriptive enough without them.
...
Here, I found the write-up. I did it for another rocket using the same setup.
http://www.doug79.com/farsides/#second-stage

Doug

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New or repaired, one of my favorite (yet short-lived) rockets. Started flying it as a single stage for a few flights, moved to two-stage for a few more flights and finally plugged the D motor of the third stage in. Found both stages, but lost the rocket. 1st stage was scorched a bit. Found the rocket in the Spring of the following year—hung high in a cedar tree about a quarter mile from the launch site. Sad really, as it was a good looking, great flying rocket.

Fix your old one and build a new one. Or, maybe build a two-stager.

A C11-0 seems like a way to make this bird actually recoverable.