On 08/30/2018 11:31 AM, Steven Schear wrote:
You don't appear to have any experience with amateur rocketry. Although perchlorate based grains can be tricky, zinc-sulphur propellants can be used safely. (My friends and I flew 24-inch ZnS rockets to altitudes approaching 10k feet and Mach 1.8 while in HS.
Groovy, but a 24 inch rocket casing does not even come close to a practical weapon in portability, accuracy or knock-down power. How much of it was taken up by fuel, vs. payload and avionics? Did it have a steering mechanism with capabilities beyond "keep the rocket vertical"?
Titanium and other exotic metals are unnecessary today. Composites can easily do the trick. As for actuators, with the right designs, amateur aircraft servos can suffice although I have seen pneumatic ones used also.
High strength, heat tolerant materials are unnecessary unless your design calls for accelerating and steering a payload that can reliably knock down an aircraft, and actually hitting targets with it. Past a cut-off point, efficiency and extra cleverness can not substitute for brute force and total ignorance. In the case at hand, existing munitions indicate that all of the above are necessary for success.
I haven't tested nor seen others evaluate the efficacy of smartphone motion sensors for combat situations but there are discrete COTS components whose specs fall within the needed ranges.
Discrete COTS components fail spec in this case, because per the stated design they they will be plugged into a "smart phone." By definition that phone is live opposition hardware radio, unless the antennas and/or radio chip are removed. That done, it's still running the opposition's software of choice unless thoroughly cleaned. By the time you're done modding the hardware and software, it's cheaper and far easier to use a Raspberri Pi or similar device. That's what they're for.
Warheads are generally scaled up shotgun shells. Flachets, ideally from tungsten but cast steel will do, are better than metal shot.
Warheads are generally high explosive shaped charges. Some deliver a single penetrator slug, white-hot and ultrasonic; others deliver shot in a narrow cone, horizontal band, or radially as in a bounding mine application. Anti-aircraft shot varies in shape and composition, typically a mix of polyhedrons and bowties, uranium of course. The cleverest warheads can deliver a selection of projectile patterns, by altering the timing of multiple primers in the driving charge. Your plane killer won't need anything that fancy. But it will need to haul a load of heavy metal and top end high explosives to within spitting distance of the target aircraft, figuratively speaking, and fire that warhead right on time.
As for safety even commercial military arms fail. I certainly wouldn't want to test even the later protyped. ISIS forces seem to have created some excellent munitions using rather rudimentary materials but clever engineering. No reason to think those living in a developed country with access to common materials and a good garage foundry and machine shop can't do better.
The only thing that calls to mind is the cheap knock-offs of WWII stovepipe artillery rockets that were carried in by ISIS to stage a "Syrian Government Chemical Weapons Attack" way back in the early days of the war. The op was fail. Other than that, ISIS & Co. appears to get the best our international gray market arms dealsers can offer, courtesy of your local CIA and its sister agencies, plus buddies overseas. It's a long, hard, complicated road from lighting a big skyrocket to shooting down airplanes, especially under the watchful eyes of State Security as per a civil uprising scenario. Your cell could get a lot more bang for the buck by preparing to attack infrastructure targets affecting industrial facilities, with "kill nobody" among the top strategic objectives. There, extra efficiency and superior cleverness do pay off compared to brute force and total ignorance. Killing people to improve the world presents as the ultimate Loser Script. To rebel as one is told, is not to rebel at all. :o)