How To Land A Model Rocket Vertically

Perhaps most readers will remember when they saw the first SpaceX demonstration of a rocket stage landing vertically on the pad under control. It’s something of a shock to be reminded that their first suborbital demonstration “hops” were around a decade ago, and how quickly what was once so special has become commonplace. We’re now in the era of the more complex model rockets having the same capability, with [] managing it last year, and now [TTS Aerospace] sharing a video showing how they achieved the same feat.

The basics of the system revolve around a directed rocket nozzle, but to make it work is a lot more complex than simply hooking up a flight controller and calling it good. The steps in arriving at a landable rocket are examined, with plenty of failures shown along the way. Even the legs are more complex than they might appear, having to combine lightness, ease of unfurling under the power of elastic, and enough strength and give to survive a rough landing.

Those of us from countries where model rocketry is a highly licensed activity can only look on in envy at these projects, and we look forward to seeing where this avenue leads next. We covered the [] rocket last year, should you be interested.

20 thoughts on “How To Land A Model Rocket Vertically

  1. This is actually a harder control problem than the Falcon 9 hoverslam, as you lose control over two of your possible control inputs: thrust (throttle) and total impulse. A solid motor has a pre-set thrust curve, a pre-set total impulse, and worse, QC means those two vary with no way to tell the actual thrust behaviour and delivered impulse until after the engine has burnt out. That means instead of being able to use engine throttle to control the vehicle (albeit with lag), the system needs to react in real-time to unknown thrust variance.

    1. Agreed, from a control algorithm perspective, this is much more impressive than what spacex does.

      … Of course, we successfully landed on the moon with a retrorocket, minimal compute, and a steady hand – the only thing that was ever impressive about spacex was the scale.

      To do this with a solid thruster is a heck of an accomplishment.

      1. The LEM had the advantage of an extremely throttleable engine: the hypergolic pintle-injected pressure-fed LMDE. It could operate down to 10% throttle, which is absurdly low for any rocket engine, and a sufficiently low TWR that the LEM could hover.
        Being able to hover makes the landing process a more tractable problem for a human pilot, though still no mean feat!
        On the other hand, rocket that land with a TWR well above 1 (e.g. Falcon 9, the OP’s rocket) must ‘hoverslam’ to land. This is a fundamentally different and much harder landing process, where you can only reach 0 vertical velocity instantaneously so much make sure you only reach it at 0 altitude, whilst also making sure you have 0 horizontal velocity simultaneously.

  2. > Those of us from countries where model rocketry is a highly licensed activity can only look on in envy

    O.O God some parts of the world really just have no freedom at all man that’s depressing.

    1. When I was a kid growing up in southern Lousiana, we needed a telescope to see if the neighbors were home. If I went out back with a model rocket and managed to blow it up and set the field on fire – so what? It wasn’t going to bother anyone.

      I live in Germany these days. The houses here are so close together that if I fart loud, people in four houses will complain. My father in law has what folks here refer to as “a large piece of land.” That piece of land is smaller than the yard (in town) that my mother has in Missouri. If something goes “bang” on my father in law’s land, the people just a 100 meters aways in the village next to it will get bent out of shape, not to mention the farmer whose (handkerchief sized) field ajoins it.

      People are too close together here. Things have to be more strictly regulated

      1. >People are too close together here.

        There’s a band that goes from Netherlands and Belgium, Germany through to Italy that has this high population density. Elsewhere in the EU is nowhere near as dense.

    2. Here in the UK it’s more of a practicality than a loss of freedom, it’s difficult to be remote enough not to risk hitting anything hence the regulations. Pretty sure you wouldn’t be allowed to fire off a rocket in downtown LA for example. On the other hand we incarcerate a lot lower percentage of our population, so who really has more freedom?

    3. You’re being (somewhat embarrassingly) histrionic in claiming the death of freedom over something so small… while also ignoring that most every country (even rifle toting America) requires licensing for rockets beyond a certain power.

      A better and more grounded talking point might be about how hobbyist involvement in creating regulations has markedly better outcomes (see US and UK) than what played out in Germany. Their regulations were created in response to a fatal accident and hence the licensing for anything over D is actually an explosives handling license, which really isn’t a good outcome for anyone.

      I think we should avoid melodrama when possible because it tends to obscure important things we can learn from situations and their outcomes.

  3. Just dig a funnel shape hole (with exost for flames). The rocket will go into the funnel, get guided into vertical position and land. You can also build some mobile/deployable structure with the same role.

  4. Odd that the grated adjustment fins of the SpaceX version are missing and it still works.
    I wonder if that is a size/weight thing.
    I don’t feel like watching the long video right now so it might be mentioned.

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