Sport Rocketry

Launch System The real SS-25 is deployed in and launched from a seven-axle mobile launch- er that is about as intimidating as the mis- sile itself (Figure 10). This type of vehicle is called a Transporter Erector Launcher, or TEL. The model SS-25 would not be quite satisfactory without its own operational port 80 pounds each, it rests upon a steel blast plate. Steel guide wires (borrowed from the Minuteman launch tower) can be attached to the raised launch sled to pro- vide extra support during launch. The rocket is centered within the tube via two sabots that support it at its mid section and lower section. Sabot pieces are constructed from 3D printed plastic collar elements (thank you, Tom Draper) mount- ed inside cardboard tube segments that are sized to slide smoothly inside the launch tube. SS-25 First Flight With an M1297W motor, the SS-25 was expected to reach an altitude of ap- proximately 4200 feet. At apogee, onboard electronics initiate separation of the body and nosecone, together with deployment of separate main parachutes for each of these two components. If the primary de- SPORT ROCKETRY JANUARY/FEBRUARY 2020 45 model TEL, so a model TEL was construct- ed (see Figure 11). The model TEL's wooden chassis rests upon 14 lawn mower wheels supported by steel axle rods. A 9' section of 10" diameter PVC pipe serves as the launch tube. The tube includes three cutouts near its base to provide pressure relief during launch. The launch tube is bolted and strapped to a sled constructed of steel angle bars and lumber cross segments. The launch sled connects to the launcher chassis via a steel pivot rod. When raised into launch position with the aid of two pneumatic pistons rated to sup- ployment system fails, a separate altim- eter can initiate a backup ejection charge deployment system five seconds after the rocket reaches apogee. The forecast for launch day included below-freezing temperatures and the pos- sibility of snow showers. Perhaps not op- timal, but also not inappropriate for our Russian ICBM. The prospect of very light winds was a relief given the fact of main parachute deployment at apogee. Upon motor ignition, flame erupted from the exhaust ports in the launch tube, and the SS-25 began to ascend. After the rocket cleared the launcher, fire advanced from both ends as if to consume the tube, and then smoke engulfed the entire launch vehicle (see Figure 13). The upper sabot separated cleanly just after the rocket ex- ited the launch tube. Separation of the Figure 12. Setting up for SS-25 launch. Photo credit: Thomas Draper. Figure 13. SS-25 first flight launch sequence. North Coast Rocketry www.NorthCoastRocketry.com Advanced Rockets that are easy to build, fun to fly and look great! Setting the standard since 1984! SA-14 Archer Lance Delta Cluster Duck

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