Hi-Flier XL Two-Stage Conversion

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smstachwick

LPR/MPR sport flier with an eye to HPR and scale
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As promised, the build thread for my Hi-Flier XL’s booster.

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The fins are smoothed with 220 grit sandpaper prior to removal from the balsa sheets.

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The fins are cut out from balsa sheets.

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The edges are sanded down to remove the “tabs” that held the fins in the sheet. I took my time on these, gently rubbing the fin stack along the sandpaper and checking every few passes.

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To produce a rounded leading edge, I kept the sandpaper on the table and “rolled” the edges of the fins, producing a nice rounding. Once each fin was rounded, I kept going on the ones that had the longest root chords until the root edges all had the same length. The spans are not all the same, but it should still be alright.

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The tube is marked. I scanned the first two pages of instructions prior to cutting out the tube marking guide, then taped it up on the tube, made tick marks, and extended the lines with a length of metal I bought at The Home Depot.

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So far this is a pretty stock build. I will be posting more updates in the following days, and I’ll be making the booster and sustainer modifications soon.
 
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smstachwick

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The motor mount is assembled. This represents the first deviation from the stock assembly, with 8 holes being drilled in each centering ring for gas venting. I can’t take credit for the idea, I saw somebody ask about the purpose of this arrangement in the centering rings that come with the SA-2061 Sasha.

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The booster will be only as long as the root chord of the fins. I hope that’s short and well-vented enough for reliable sustainer ignition. The nice thing about doing it this way is that I don’t have to snip the motor hook, it can just fit into the full inner diameter of the booster’s tube.
 
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smstachwick

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When I took a break from this to construct my Super Hi-Flier, I had already gotten the fins glued on. Now the body tube is cut almost to length and the motor mount is installed.

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I plan to sand until the forward end is flush with the fins. Clearly I have some way to go.

After this comes the coupler cutting and installation, and the repair to the sustainer’s tube.
 

smstachwick

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The booster is flight-ready, with the body tube sanded to length and the coupler installed. The glue is drying now.DB208B09-356E-4E94-969D-D9C268B8174C.jpeg
 

smstachwick

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It's looking great. This is a very informative build thread.
Why thank you! I steal from the best.

One thing I haven’t mentioned but I feel like I should is the amount of trimming I did on the base of the sustainer’s motor mount. I went a little overboard with the epoxy in the original build and I really had to go to town on it with my knife and 220 sandpaper to get the booster’s coupler to fit. I’m still not really happy with how tight it is in certain orientations, but I’ve also learned that I tend to underestimate how capable the Estes motors are. I’m thinking that if I can separate them with a quick and mild-to-moderately forceful jerk, that should be good enough. I’d be a lot more worried if I had to give it a sustained tug. Plus I can sand the booster coupler now that it’s installed.

UPDATE: The sustainer is lengthened past the crush point. Trimming will come later, possibly this evening.

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smstachwick

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Ok so my improvised repair coupler didn’t work, the bond failed while attempting to cut the new tube. I found the actual coupler that shipped with the booster kit, previously cut, and attached it to the opposite end of the new tube. I’m going to leave it for a while before I actually try to make the final body tube cut. The bottle says a full cure takes 24 hours, so I will likely leave it until that time before attempting that.

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The good news is that I have enough tube that I can start over for a (hopefully) neater second attempt at the cut, the blade strayed a bit past the line I had marked on the first attempt.

After that is the redone shock cord mount installation and then onto my next conversion.
 

smstachwick

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Magic 8 ball predicts a lot of sanding in my future. Done tonight? Don’t count on it.

Or another tube cut? Signs point to yes.

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smstachwick

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Well, I got the tube cut last week. Today I installed the recovery system. Estes tri-fold glued to a new shock cord, tied to the original shock cord with a simple square knot. The original parachute got replaced too, as I had under-packed it during early flights with DART and Tripoli and scorched it a bit. I pulled out one of the new chute’s shroud lines during a pop test but it survived another pop test with some masking tape.

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I also glued a launch lug segment onto the booster. I don’t know if it will be possible to align it in a way that will allow a launch rod through. If not, I’ll snap it off at the pad and possibly reconfigure/realign all three at my camp. Maybe the RSO will allow it to fly on the sustainer’s lugs alone but I’d feel safer with the additional guidance.

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That is essentially flight ready. Pack it up and pray for its return.

Maiden flight in this configuration will occur at LDRS-40 this week, likely on an E12-0/E12-8 combo. Going for broke.
 
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