X-Git-Url: https://git.gag.com/?p=web%2Fgag.com;a=blobdiff_plain;f=rockets%2Fairframes%2FRG-2%2Findex.mdwn;h=0e4eacb506d80e72527ef0f70e53846c7411f452;hp=d39a6c129dda26fec81aa1bafaddf063a3d289ca;hb=c6605540deeedafceb1291ef26cba2458b41b084;hpb=3d26486262ddf85e319c938566fdd821b5bb90e1 diff --git a/rockets/airframes/RG-2/index.mdwn b/rockets/airframes/RG-2/index.mdwn index d39a6c1..0e4eacb 100644 --- a/rockets/airframes/RG-2/index.mdwn +++ b/rockets/airframes/RG-2/index.mdwn @@ -10,6 +10,10 @@ ground on a G motor. The timing coincided with the first prototype builds of [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 @@ -25,5 +29,74 @@ on designing the rocket to fly one. ## Build +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.