Search the Community
Showing results for tags 'retropropulsion'.
The search index is currently processing. Current results may not be complete.
-
My kids love watching rocket launches, so I got them some model rockets and we were launching them. I had also made my oldest a 1:80 scale model of the Falcon 9 with pop-out grid fins and landing legs. He kept asking me when we could launch his Falcon 9 and make it land on a boat. So I got to thinking...how hard would it be to build a hobby rocket with propulsive landing capability? Proper timing for a true suicide burn is hard enough with a liquid-fueled rocket; it would be even more difficult with a solid-fueled rocket, even if you had a laser rangefinder. Instead of trying to do a true suicide burn, then, you could build your model rocket with over-engineered shock-absorbing landing legs. Then, with slightly oversized grid-fin-style airbrakes, the terminal velocity would be fairly low. You could get away with a TWR < 1, since you would only need to decrease terminal velocity, not zero it out entirely. Your landing legs would catch you regardless of whether the motor burned out a few feet above the ground or was still firing on landing. Here's a 1:40 scale model, reproduced in SketchUp. Two stage rocket. Eight motors for ascent; central motor is reserved for landing. The octaweb at the base holds the launch and landing motors, mounts the landing legs, and holds the leg deployment channels (they are deployed by the landing-motor ejection charge). It is either aluminum or dense resin. The legs are likely either aluminum or PVC. They snap into place at the top and are deployed by springs (not shown). Main body (C) is light plastic to allow it to be launched without a license. Fairing halves (A) and (B) are plastic. Upper stage (C) is dense 3D-printed plastic; interstage (D) and "grid fin" air brakes (E) are either aluminum or dense resin. The landing ignition wire guide (F) is also light plastic. Detail view of interstage and upper stage: On ascent, the landing legs serve as a sort of shuttlecock to maintain guidance, with the upper stage providing sufficient counterweight. Return airbrakes on the lower stage and guidance brakes on the upper stage both pop out on springs at stage separation, which also closes a circuit to ignite the upper stage motor. On upper stage burnout, fairing halves pop out to deploy parachutes; these are tethered to the second stage (not shown) and allow for recovery. Lower stage descent and landing:
- 15 replies
-
- 1
-
- spacex
- retropropulsion
-
(and 1 more)
Tagged with: