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$96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

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Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#231

The engineering is genuinely impressive for $96, but naming the repo "MANPADS-System-Launcher-and-Rocket" on GitHub is going to attract exactly the kind of attention you don't want. ITAR implications aside, the interesting part is the mid-flight trajectory recalculation on a $5 sensor. That's the same basic problem military guidance systems solve with hardware that costs thousands. The gap between consumer electronic…

More than the electronics, I would be curious about the performance of 3d-printed plastic parts on a rocket. Are they strong enough?

3d printed PLA and spiral wound cardboard is generally fine for hobby rockets, until they start going supersonic - then you need metal.

I'm not sure the launch tube could withstand the heat of the rocket exhaust though. Although that might depend what it is printed with.

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#232
post #138

Earlier quoted context omitted.

Yes, I don't think this project is a serious threat as a weapon, it's more interesting if viewed as a politically provocative stunt, to get people thinking about the relationship between technology and war.

I always wonder why rockets are millions of dollars each, that seems insane to me.

They arent. Missiles cost millions. Rockets are cheap. Rockets are unguided. Missiles are guided. From a military perspective, spacelaunch rockets are techically "unguided" as they are not tracking a target but trying to stick to a fixed/programed trajectory. It is the seeker head that costs the millions, all the jamming/counter-jamming tech that drives up development costs.

This is a rather basic (passive) seeker head by modern standards.

https://en.wikipedia.org/wiki/File:R-27_missile_homing_head,...

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#233
post #88

There are 2 short segments in the video showing the actual performance and thus far it is a complete [1] failure [2]. The guy has a talent, and he put together a nice prototype based on OpenRocket [3], but with all due respect, this is not a rocket, and you are not going to win any war with this toy, even if all your enemy has are rocks thrown at you from pretty much similar distance. The remix of computer games / Uk…

Something far more interesting, you can find in this channel: https://m.youtube.com/@LafayetteSystems

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#234
post #76

This is obviously a missile, and I'm not well-versed in weapons tech, but won't this need a camera to actually track and take out a flying object? So far I just see gps and barometric sensing... Also 3D printing and some electronics, ok fine, but where do you get the rocket propellant? That seems at least as critical as the software and sensing side of things...

> rocket propellant You can homemade it, kno3+sugar

You can also blow your hands off, blind yourself and/or burn down the building. So be very careful if you try this. Note it is illegal to make your own solid fuel motors in some countries (you need a special license in the UK).

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#235
post #88

There are 2 short segments in the video showing the actual performance and thus far it is a complete [1] failure [2]. The guy has a talent, and he put together a nice prototype based on OpenRocket [3], but with all due respect, this is not a rocket, and you are not going to win any war with this toy, even if all your enemy has are rocks thrown at you from pretty much similar distance. The remix of computer games / Uk…

Regardless, he made a prototype rocket enclosure and he seems to have the software down… I think the propulsion system will be the easy part. Hardest part will be tuning the PID so that the rocket goes where he wants it to. Then incorporating his tracking system will be another challenge of itself but that’s because of the form factor. As long as his calculus and linear algebra is good I see than being successful. Ei…

> I think the propulsion system will be the easy part.

Really? I think rocket science is still not easy. Just look at how much nation states are spending on maintaining their liquid and/or solid fuel rocket programs. If they even have one, let alone both.

This book might give some insights into the why https://library.sciencemadness.org/library/books/ignition.pd...

Quote: "All this sounds fairly academic and innocuous, but when it is translated into the problem of handling the stuff, the results are horrendous. It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water —with which it reacts explosively. It can be It has recently been shown that an argon fluoride, probably ArF2, does exist, but it is unstable except at cryogenic temperatures.

[...] kept in some of the ordinary structural metals — steel, copper, aluminum, etc. —because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes."

Granted this is about a fuel that is AFAIK not used for MANPADs, but the joke about the running shoes could be made about most aspects of rocket propulsion.

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#236

Earlier quoted context omitted.

Unbombed people are cute.

That's why it's so important for people who can hold a moral line, to do so. Violence breeds violence. A good engineer in America can afford avoiding weapons work.

it's good work if it helps the right people

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#237
post #197
post #152

Earlier quoted context omitted.

You don't need to win any wars with it if you can use them to sow confusion, obscure the firing of more serious rockets, and/or trigger a sufficiently more expensive response. It clearly needs more work, but if an amateur can get this far at this low cost, odds are you'll see attempts at overwhelming attackers or defense systems by sheer volume with cheap decoys like this long before they become an actual threat in a…

Exactly. Consider the current conflict in Iran. They have thousands of drones that cost $50k each. The US’s only real defense against one of these drones is to fire a million dollar missile at it. That assymmetry can win or lose a war.

It's not the only real defense. This works pretty well too https://en.wikipedia.org/wiki/Centurion_C-RAM

There's clearly a need for more cheap interceptor drones as well, but it's not like the US military won't start deploying those soon enough.

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#238
I remember an anecdote our robotics lecturer told our university class in 1995, which was about how in the west we try to make expensive things that are the absolute best of technology and how the other side didn't have that luxury and relied on ingenuity.

He described a cold war Russian missile they had somehow obtained and were tasked with trying to reverse engineer. Ostensibly, it was thought to be a heat seeking missile, but there seemed to be no control or guidance circuitry at all. There was a single LDR (light dependent resistor) attached to a coil which moved a fin. That was it. Total cost for the guidance system maybe a couple of dollars, compared to hundreds of thousands for the cheapest guidance systems we had at the time.

The key insight was that if you shined a light at it, the fin moved one way and if there was no light the fin moved the opposite way. That still didn't explain how this was able to guide a missile, but the next realisation was that the other fins were angled so when this was flying (propelled by burning rocket fuel), the missile was inherently unstable - rotating around the axis of thrust and wobbling slightly. With the moveable fin in place, it was enough to straighten it up when it was facing a bright light, and wobble more when there was no bright light. Because it was constantly rotating, you could think of it as defaulting to exploring a cone around its current direction, and when it could see a light it aimed towards the centre of that cone. It was then able to "explore the sky" and latch on to the brightest thing it could see, which would hopefully be the exhaust from a plane, and so it would be able to lock on, and adjust course on a moving target with no "brain" at all.

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#239
post #218

Earlier quoted context omitted.

Lasers won’t effectively work, it’s a two part equation, detection and targeting. To neutralize a target using a ground-based laser, you need an enormous power, and still it won’t penetrate a high distance/altitude in the sky, environment factors also to be considered. The detection part is even harder, these small 8in drones are almost impossible to detect unless you can hear it, aka it’s over, because they can fly…

8 inches drone cannot carry much of explosive at all. In order to dump 10 kg load of explosives, you need an “agricultural drone” one that can carry 45kg, since the additional mechanisms and their batteries (and the drone’s backup batteries) are heavy. Those are bigger and noisier. DJI ARGAS Series are good starting point. https://ag.dji.com/mobile

Last week I was flying the argas! But I think you are misunderstanding, these are suicide drones not dropping the payload kind, and 8in can very well carry a deadly explosive, mostly against personnel, vehicles ones you get it bigger but not by much, from 12-18in max.

Re: $96 3D-printed rocket that recalculates its mid-air trajectory using a $5 sensor

#240
post #140

Earlier quoted context omitted.

100 rockets for $10k is not happening. The price floor is not dictated by the electronics (which did get cheaper), it's dictated by the rest of the system: propulsion, warheads, arming and safety, QA, traceability, climate and shelf life stability. Take a look at Raytheon's manufacturing line: https://www.youtube.com/watch?v=kCCkVAHSzrc That's what it takes to have missiles that are nearly guaranteed to perform to sp…

TFA is literally about a $96 rocket. > propulsion, warheads, arming and safety, QA, traceability, climate and shelf life stability. You're entirely missing the point. These do not need to be reliable for the scenario I hinted at. They also do not need to be armed. They need to be large enough that if one of them is a higher quality rocket (not part of the $10k) that contains actual explosives, you have serious destru…

> TFA is literally about a $96 rocket

It's a firework-grade rocket with no payload that can't even ignite reliably.

To imitate even a TBM or a MBRM, you need similar kinematics, even if you're running without a payload. Maybe your solid rocket motor would be a touch smaller because you're not delivering hundreds of kilograms of explosives, but it still has to be large because of the rocket equation. With a large motor you're looking at a lot of damage if it explodes at the launch point, so you need quality casting. You can't really save much money on the motor.

Then, you need a TEL. Because the motor is large, the launcher has to be comparable to the real thing. You probably don't want to have two different vehicles, so you keep the same vehicle; it needs to be armed, driven around, and set for launch. Not that different from the real thing.

So you've done all of that, and then you realise that your empty warheads are too light and the missiles (or warheads, if you split) don't interact with the atmosphere in the same way as non-decoy missiles do. What's worse, modern radars are perfectly capable of noticing that and discriminating the decoys. All of that effort, and you didn't win anything. Might as well add the payload.

The US and the UK spent vast amount of money chasing exactly your line of reasoning with nuclear warhead decoys. Chevaline is a culmination of the effort, and it's retired for 30 years. In the end, relying on decoys doesn't really work, they are too expensive.

Fancier CPUs change very little of this calculation, because compute is a very little part of the cost to begin with.

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