[TeleMetrum v0.2](http://altusmetrum.org/TeleMetrum), so naturally he insisted
on designing the rocket to fly one.
+Bdale and Keith both liked the design and wanted to join in the fun, so the
+plan is to be ready for a 3-way drag race on Cesaroni Pro29 full-G motors
+at [NCR](http://ncrocketry.org) Mile High Mayhem 2010.
+
## Design Details
* 38mm phenolic air frame
The build began on 21 March 2010, cutting all the phenolic and fin blanks for
4 "kits" of parts.
+The first step was to CNC machine all the rings and bulkheads, then clean them
+up and fit them by sanding carefully.
+
+Next, we cut out the fins using our radial arm saw, and beveled them by hand
+using sandpaper flat on a table surface, hand-holding the fins at the desired
+bevel angle. Bdale cheated a bit on his fins using his Dremel with sanding
+drum to quickly remove most of the material then finishing up with sandpaper
+on the table... but that requires a very steady hand with a Dremel! We
+beveled the leading and trailing edges for looks and to reduce drag, but
+since these rockets won't break mach on a G the exact profile isn't critical.
+
+Assembly started by sanding the outside of the 29mm phenolic motor mount,
+and using a piece of angle to mark a reference line along the entire length
+of the mount. We use this reference line to get the first fin aligned
+perfectly. Next, we put the two fin-locking rings on the MMT along with the
+HAMR retainer body, and used the fins to work out from the aft of the MMT
+exactly where the fin-forward ring needed to be, marking the aft edge of this
+ring's position on the MMT. The fin forward ring's position is the critical
+part of building a fin can the way we do, so we take extra time to get this
+right.
+
+We then smeared 5-minute hobby epoxy around the MMT at this mark, and
+pushed the fin-forward
+ring into place from the aft end of the MMT, pushing an epoxy fillet on the
+ring's leading edge, and leaving the aft side of the ring fairly dry. We
+align the ring so that one of the locking tabs is positioned with one edge
+on the line up the MMT, so that when we put the first fin in place we can use
+that line to ensure it's straight along the MMT. And we're very careful to
+make sure the ring is "square" to the MMT. While we have some spare epoxy,
+we also smear the front of the MMT and slide on the zipperless fin can ring
+from the front. Then we let the epoxy cure. Do *not* glue the aft ring to
+the MMT yet! That comes much later.
+
+To be continued...
+
## Flights
+All three prototypes were first flown at [NCR](http://ncrocketry.org) Mile
+High Mayhem 2010, on the new Cesaroni 159G54 c-slot long burning red flame
+"full G" motors.
+
+Bdale's broke a mile, but we somehow failed to pull the
+[TeleMetrum](http://altusmetrum.org/TeleMetrum) data before re-using the board
+in another airframe, so we can't prove that. However, the fin can separated
+and has not been recovered. So much for painting a tiny fin can black!
+
+We learned the hard way with Robert's airframe that silver Krylon paint is
+metallic enough to hamper GPS reception, but the UHF downlink was strong and
+we found the rocket easily using RDF techniques. Robert's also separated at
+apogee, but thanks to the flourescent pink paint
+job, it was found between the rest of the airframe and the flight line.
+
+Keith's flew nominally.
+
+Robert flew his for the second time at Tripoli Colorado's Spring Fling 2010,
+again on a 159G54. It dragged a bit on the rail, ended up in a non-vertical
+trajectory, and again failed to break a mile AGL. Oh well.
+
+## Conclusions
+
+This is a fun little rocket, and is indeed capable of breaking a mile AGL
+from Colorado launch sites using the 159G54 reload from Cesaroni. It was
+Robert's first introduction to flying drogueless dual-deploy. Building
+without the Giant Leap rail guides and tower launching would be a good
+plan for future renditions to get more altitude, though as Robert points out,
+that would make it harder to sport fly at random launches. The slide-in
+ebay design worked out very well, and keeps the number of airframe junctions
+down.
projects / web / gag.com / blobdiff