Crash-n-Burn
Well-Known Member
- Joined
- Aug 14, 2014
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- 377
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Hi folks,
This'll sort of be a build/fail/fix/fail retrospective and a possible V2.0 build thread. No timeline on the build but I can tell the history now.
I have not made it to a club launch in over a year, mostly due to weekend activity commitments for my kids. At some point I started getting itchy to burn some F/G motors and I have no non-club field suitable for such and activity... unless I devise a super draggy motor burner. That led me to build a spool rocket.
This was going to be a spare parts hero - scrap plywood and an orphaned Estes PSII 29mm MMT. The motor mount is an 8" long craft tube. I figured on 5 3/4" diameter spool ends through the highly scientific process of WTLO (well, that looks okay). A bit of bandsaw and router work produced two nice 1/4" thick spool ends. I sandwiched them, measured for the center, and drilled holes for the motor tube and for a 1/4" launch rod. Some 5 minute epoxy and I had a working spool after about an hour of work.
I decided to fly it later that day on an F44. Why I chose a 24mm motor that required an adaptor is a testament to me making things harder than necessary, but in the end I got everything friction fit and ready to go. That first launch was successful - up and tumble recovery down. Estimated apogee was 125'. Upon recovery, I found that the motor tube and crinkled along the spirals. Despite my kids imploring an encore flight, I chose to retire to the basement for modifications.
Several days later, I came across a $3 bag of Bondo fiberglass cloth at Wal-Mart. I've never glassed a tube before but this looked doable and cheap. This fg cloth feels heavy but in some way that makes it perfect for this project. I invested twenty minutes in watching Jon Coker's glassing a tube video, then measured out four wraps of cloth that would fit neatly between the spools. I spread West Systems 105/205 on the cloth (which was laid out on a piece of wax paper). After cleaning up the excess epoxy, I used the wax paper to start the rolling process. It worked surprisingly well; the spool ends gave me something to hold on to and steer with. After getting the tube wrapped, I wiped off a bit of excess epoxy, wrapped the tube in plastic wrap, and let it be for a while.
Next morning - this morning - I unwrapped my first glassed tube. I must say that it came out better than expected. This wasn't winning any craftsmanship contests, but I was pleased with a serviceable and strong tube. I loaded up the launch equipment, an F52 and a G76 and got ready for some fun.
My lantern battery was dead so I made a quick trip to the local hardware store and then there was nothing stopping this launch. My younger son gave us the countdown countdown and whoosh - perfectly straight up, nice tumble down. Touchdown, bounce, watch a spool end roll away. Dinkin' flicka.
Observation of failure are pretty obvious - the craft tube delaminated from the force of hitting the ground. About 50% of the plywood fillet area around the motor tube delaminated as well. The two pieces do not fit back together nicely and there's no reason to think a fix would eliminate a repeat occurrence. So This G** D***** Spool is headed for the Frankenstein pile.
V2.0 will use a proper FG mmt from a DX3 mini (which will some day become a 38mm MD project now). I'll cut more plywood and try again. I might even rig in a small parachute and motor retainer on the next version. That really depends on my potentially waning interest in this project. i'll leave it to y'all to keep me motivated.
This'll sort of be a build/fail/fix/fail retrospective and a possible V2.0 build thread. No timeline on the build but I can tell the history now.
I have not made it to a club launch in over a year, mostly due to weekend activity commitments for my kids. At some point I started getting itchy to burn some F/G motors and I have no non-club field suitable for such and activity... unless I devise a super draggy motor burner. That led me to build a spool rocket.
This was going to be a spare parts hero - scrap plywood and an orphaned Estes PSII 29mm MMT. The motor mount is an 8" long craft tube. I figured on 5 3/4" diameter spool ends through the highly scientific process of WTLO (well, that looks okay). A bit of bandsaw and router work produced two nice 1/4" thick spool ends. I sandwiched them, measured for the center, and drilled holes for the motor tube and for a 1/4" launch rod. Some 5 minute epoxy and I had a working spool after about an hour of work.
I decided to fly it later that day on an F44. Why I chose a 24mm motor that required an adaptor is a testament to me making things harder than necessary, but in the end I got everything friction fit and ready to go. That first launch was successful - up and tumble recovery down. Estimated apogee was 125'. Upon recovery, I found that the motor tube and crinkled along the spirals. Despite my kids imploring an encore flight, I chose to retire to the basement for modifications.
Several days later, I came across a $3 bag of Bondo fiberglass cloth at Wal-Mart. I've never glassed a tube before but this looked doable and cheap. This fg cloth feels heavy but in some way that makes it perfect for this project. I invested twenty minutes in watching Jon Coker's glassing a tube video, then measured out four wraps of cloth that would fit neatly between the spools. I spread West Systems 105/205 on the cloth (which was laid out on a piece of wax paper). After cleaning up the excess epoxy, I used the wax paper to start the rolling process. It worked surprisingly well; the spool ends gave me something to hold on to and steer with. After getting the tube wrapped, I wiped off a bit of excess epoxy, wrapped the tube in plastic wrap, and let it be for a while.
Next morning - this morning - I unwrapped my first glassed tube. I must say that it came out better than expected. This wasn't winning any craftsmanship contests, but I was pleased with a serviceable and strong tube. I loaded up the launch equipment, an F52 and a G76 and got ready for some fun.
My lantern battery was dead so I made a quick trip to the local hardware store and then there was nothing stopping this launch. My younger son gave us the countdown countdown and whoosh - perfectly straight up, nice tumble down. Touchdown, bounce, watch a spool end roll away. Dinkin' flicka.
Observation of failure are pretty obvious - the craft tube delaminated from the force of hitting the ground. About 50% of the plywood fillet area around the motor tube delaminated as well. The two pieces do not fit back together nicely and there's no reason to think a fix would eliminate a repeat occurrence. So This G** D***** Spool is headed for the Frankenstein pile.
V2.0 will use a proper FG mmt from a DX3 mini (which will some day become a 38mm MD project now). I'll cut more plywood and try again. I might even rig in a small parachute and motor retainer on the next version. That really depends on my potentially waning interest in this project. i'll leave it to y'all to keep me motivated.
