Right Back Where We Started From

Not all that long ago, rocket launches were relatively rare events. This was in large part because the costs involved were massive and very few parts could be reused between launches. But that was before the private sector got involved in launching rockets and spacecraft, with SpaceX now leading the way. At present, rocket launches typically happen every few days. In fact, they are so commonplace that many people are unaware of most of the launches that are happening.

Many innovations have combined to bring us to this point, but one of the most important is the reuse of rockets. Today’s cutting-edge rockets return to Earth after delivering their payload into space, burning descent engines at the last second to land precisely on a predetermined target. These technologies may be well out of the reach of hobbyists, but that did not stop Aryan Kapoor of JRD Propulsion from attempting to build a propulsive landing system into a model rocket.

While Kapoor’s setup is far simpler than what powers a full-sized rocket, it still works using similar principles. Rather than using fins for stability and a parachute for descent like a typical model rocket, this custom rocket uses a thrust vector control system and separate ascent and descent motors. An onboard flight computer, equipped with a microcontroller and sensors like a barometer and accelerometer, manipulates servo motors that pivot the engine housing, which is attached to a gimbal.

These movements are carefully choreographed by custom flight control software that keeps the rocket in a stable flight path. After the ascent motor has been exhausted, it is ejected with the help of a pair of springs. Gravity takes over at that point, but when the sensors indicate that the rocket is at the proper altitude the descent motor is ignited. The flight controller then ensures that the rocket stays upright as it slowly descends. Clever landing gear absorbs the shock of landing with plastic syringes and rubber bands.

As you might expect, there were a number of failures along the way that Kapoor learned from before arriving at the present state of the system. But after dealing with sensor problems and motor failures, the model rocket was shown to be capable of stable flight and a soft landing.

Moving forward, Kapoor plans to continue refining the propulsive landing system to make it more reliable. All of Kapoor’s work is open source, so if you are into model rockets, be sure to check out JRD Propulsion for some major upgrades to your gear.