Estes Generic E2X (crude) Repair

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smstachwick

LPR/MPR sport flier with an eye to HPR and scale
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After having a water recovery at last week’s DART launch, I finally got my Generic back to flight-worthy condition.

First things first, though: removing that soaked motor! It was more of a job than the D12-5 that drowned in my Hi-Flier XL, with the paper casing collapsing into a dense, hard pack that was very difficult to get a grip on with my pliers. Like dog barf that was welded in.

My relentless attack on the casing ended up splitting the body tube seam, so as my mind was mostly idle while picking scorched and damp paper out of the mount, I started thinking about what I was going to do about the ruined tube. I couldn’t just fly it that way. It was structurally unsound, and probably wouldn’t survive the pressure of ejection even if it somehow managed to remain rigid. I’d need something to stiffen the tube and make it airtight, like a coupler or sleeve.

It’s a BT-50 kit, with a 24mm inner diameter. Too bad I didn’t have any spent motor casings around, that would have made things easy. Cut the nozzle out, either remove the shock cord mount or cut the tube, glue the casing in place, and put the rocket back together. If only I had a spent D12 lying around.

Or a C11.

A D12 or a C11….

C11….

THAT’S IT!

I had static fired a couple of C11-7s to make the spike for my Estes Goblin. With that thing out of commission and unlikely to fly again until I can next get out to TRASD or ROC, I quickly decided to cannibalize my 24x70mm spike for use in my Generic.

As soon as I got the stuck C6-3 free, I ripped the spike off the rack and snapped the two glued-together casings apart. I sanded one of them down, removed its nozzle, cut the Generic’s tube (a pretty rough job, I admit) and got it nice and snug in there. Next I put a little glue on the casing and slid it a fraction of an inch into place.

16E20930-0A7A-4CB7-B918-3A1167277C3B.jpeg
I slid the other body tube segment on, glued it in place, glued the forward lug back on (it had also snapped off during motor removal), and packed it for recovery. The CG is pretty close to the joint, which is pretty far back, but I had loaded it with a C6-7 and no wadding, so that’s basically worst-case scenario. I can put some strengthening near the other set of crimps in the tube if need be (I left them alone because they’re not as bad) or cut it again to lighten the casing-turned-coupler.

81EC477C-143C-4D4E-A8D4-47AD422A3DC7.jpeg

I think I’m pretty creative with my use of spent casings but I don’t think I’ve used one as an inetegral airframe component before. This is a first.
 
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Awesome! I always repair and fly again when I can. I've used spent engine cases as Motor Blocks and bases (along with a sharpie cap or caulk tube tip) for home built nose cones for my Tester rockets.
 
That thing should be strong enough to make that GE2X a 100-flight bird!
Oh, don’t I wish. I later converted it to a two-stager and it suffered another great injury at the DART field.

I got out to the range today after over a month since my last opportunity to fly. Today was a good day.

I only managed to get two flights off. First up was the maiden flight of my Super Generic E2X, basically a Mongoose the hard way. Nominal flight on an A8-0 / A8-5 stack, although OpenRocket was correct with its prediction of excessive arcing.
View attachment 516546
About the only bit of trouble was the booster’s motor hook disappearing into thin air. It was nowhere to be found when I recovered the booster.

For the next flight I decided to up the ante a bit and upgrade the sustainer to a B6-6, angling the rod a bit closer to vertical for a straighter flight. This one was less than successful. The stages separated but the sustainer failed to light. At first it fell sideways, its fins rolling it, but in the last portion of its descent it straightened and impacted the surface with a good thud. It was at that instant I was glad I had decided to keep the booster motor pretty small for the first few launches. If it had come in from the altitude that a C6-0 would have put it at, that could have been trouble.

I enter frame at T+ 0:22 to recover the rocket.

View attachment 516552


View attachment 516553This is the third time I have had this error. The first was with my Super Gnome, where my application of tape was nowhere near strong enough to hold the motors together long enough to stage. I improved my technique and got it to work reliably enough at November ROCstock and subsequent launch events. The second was with my Super Star Trooper with DART. I did not determine the cause of this failure at the time but my best guess was that the remnants of the booster propellant grains simply missed the nozzle. That rocket was also small enough to tumble back without damage. This larger, heavier one wasn’t so lucky.

I solicited some troubleshooting input from the other fliers at the range. Jim Myres from Discount Rocketry examined my rocket and he mentioned the gap staging techniques with which I was already familiar, pointing out that the pressure probably popped the booster off before the sustainer could ignite. I was puzzled as to how this was possible, since I’d taped the motors together with what I thought was decent technique, but since packing up for the day I think inclined to agree with him.

Since getting involved in rocketry again, I’ve noticed that the cellophane tape that I packed in my range box is pretty weak in terms of adhesive strength. It’s not exactly the kind of weak that you’d find on a Post-it note but it’s substantially easier to remove from surfaces than the translucent Scotch tape with which I’m sure we’re all familiar. My guess is that he is indeed correct, the motors were not held in place firmly enough.

I also now believe that this was the reason for my Super Star Trooper’s staging failure.

After that conversation I returned to my table and removed the unused B6-6 motor. The friction fit was a bit too tight, so I ended up pulling out the entire mount and cutting the motor mount tube to get the motor free. Given the previous water recovery and today’s nose-first crash, I think this rocket has earned retirement.

I ended up buying a pair of standard Hi-Fliers from Jim’s trailer to continue flying 18mm two-stage at the next DART launch and possibly LDRS. Hopefully a new roll of tape will resolve my staging woes and this won’t happen again for a while.
It currently resides in my drawer of broken rockets that I have no inclination to fix and have replaced but I have not yet needed to cannibalize. I could theoretically repair it, but I maintain that this is an act of mercy for a rocket that has endured far more than it was ever intended to.
 
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