This is a "replacement" for Bdale's first L3 certification airframe, YikStik, which was mostly lost. The name was suggested by Bdale's wife Karen to imply that it's in homage "to YikStik". The project sat as just a simulation file for a long time, until Ed Shibadeh from Giant Leap admitted at Airfest 16 that he had one last 98-75mm Slimline Tail Cone in his personal collection that he would be willing to let Bdale have. It's silly how much the little things matter sometimes! The tailcone wasn't even part of the early YikStik design, but once it was added it somehow became an important element of the overall design that Bdale wasn't willing to do without on this project...
Meanwhile, Robert became interested in measuring the temperature of a nose cone and a fin on a rocket at speeds above Mach. This led Bdale to design a TeleMetrum companion board called TeleScience capable of hosting up to 12 NTC thermistors for temperature data collection. The plan is to fly two TeleMetrum+TeleScience setups, one mounted in the nose cone and one mounted in the fin can. The one in the fin can will be responsible for apogee deployment, and the one in the nose cone will handle main deployment.
Jeff Lane of Shock Wave Rocketry expressed a willingness to fabricate a custom 98mm nose cone with the temperature sensors embedded in the glass layers, as he is also interested in the data we hope to collect.
- 98mm Giant Leap Dynawind air frame
- 75mm PML phenolic motor mount
- Shock Wave Rocketry fiberglass 98mm Von Karman 6:1 nose cone
- custom fins, using 6/16 inch birch plywood laminated with carbon fiber and a fibreglass sanding veil
- 3/8 inch birch plywood centering rings and bulkheads, CNC milled, the two that hold the fins are double thickness (3/4 inch) and notched for perfect fin alignment.
The OpenRocket design file is 2YikStik.ork.
The temperature sensors chosen are 0.8 mm diameter glass bead NTC thermistors made by EPCOS, model B57540G0303F000. These were chosen because of their small size, and turn out to have a very fast response time to changing temperatures.
The leads were extended with 30 gauge wire wrap wire using twisted pairs of black plus a color. The colored lead was insulated from the bead back over the solder joint using 1/16 inch heat shrink tubing. The epoxy used for the nose cone and fin was tested and confirmed to have essentially no conductivity.
The airframe geometry led us to decide to build two electronics bays, one in
the airframe immediately aft of the nose cone, and the other in the fin can.
Each bay holds a production TeleMetrum, a prototype companion board called TeleScience, a 900 mAh LiPo battery, and a power switch.
The TeleScience board supports connection of up to 12 NTC thermistors along with other capabilities.
Installing the electronics in the fin can bay was .. interesting. More later.
Parts gathered during October 2010. Built mostly during April and May 2011.
The nose cone was custom fabricated by Jeff Lane at Shockwave Rocketry, with thermistors embedded.
The fins are 3/16 inch birch ply, tapered on the leading and trailing edges, then covered with one layer of 5.7 oz 2x2 twill carbon fiber and a layer of 6 oz glass as a sanding veil, all vacuum bagged with West Systems laminating epoxy using a kitchen food saver appliance.
The airframe tubing is Giant Leap Rocketry 98mm Magnaframe-based Dynawind, except for a short section behind the nose cone that uses the older phenolic based Dynawind because of the slightly larger inside diameter being a better fit for the glass nose cone shoulder.
The tailcone is a no-longer-available Giant Leap 98-75mm Slimline tailcone.
All rings and bulkheads were cut using a CNC milling machine from 3/8 inch birch plywood. The fin forward and leading edge rings are made from 3/4 inch thick assemblies made by laminating two such rings with wood glue, to provide sufficient depth for milled fin slots.
Assembly techniques were "nothing special" except for the electronics... but I kept a log that may be of interest.
The original objective of flying 2YikStik at NCR's Mile High Mayhem 2011 was not met due to weather conditions unfavorable for a high altitude launch.
We flew 2YikStik at LDRS 30 on Friday morning. The first couple seconds were glorious! Unfortunately, we hit a wind shear layer just as we were approaching mach, and the side pressure on the nose cone apparently snapped the coupler behind the nose bay, causing the remainder of the propellant to be expended sky-writing instead of going up. Way too exciting!
The airframe didn't get going fast enough before the incident to log any interesting skin temperature data, but the sensor in contact with the motor casing showed the anticipated rise as the motor burned, so we believe the TeleScience boards were working fine.
Jeff Lane took this video of the flight.
YikStik3 will be our next attempt.