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Author	Topic: Home-Built Heat Seeking Missile Theory
Jolly Roger Frequent Poster	posted September 13, 1999 06:31 PM Has anyone ever actually seen a pulsejet run? I have built one from some plans off this blokes site, ages ago, and it glows red hot as it runs. This could cause some serious problems if the explosives are heat sensitive!!! Also these engines are banned in most countries due to the fact the planes they are on top 200+MPH!!!! Just you try flying a plane that fast! I fly at (almost) competition level, and a plane flying at 100MPH is impossible for a beginner. One more problem withthese engines is you can hear them coming miles off. I get complaints as far as a mile up the road when I run it. An HLG glider could be built with simple two channel gear which could be picked up as cheap as $20 a set would work fine, and it would be quiet. You could practically fly it into them without them hearing it. Or you could buy one. Whatever....
VeHeMT Frequent Poster	posted September 13, 1999 08:33 PM Hehehe Those planes are hot, noisy and fast? Did you think a rocket was anymore different? bwahahahahahaha! When the target is much further away and the plane design is very stable it wont be impossible so long as you have at least some skills in RC flying. A homemade "cruise missile" ( somewhat a cross between the two) would offer the best performance. In essence a plane with a pulsejet on it and a bomb would be somewhat of a cruisemissile. For striking structures an unguided rocket "aimed" at the structure would suffice hehe.
Predator Frequent Poster	posted September 14, 1999 08:47 AM I'm sure it's very easy to silence the jet enginne, just by adding a oversized steel "firearm type silencer" to it.. this should, in theory, with a little modification make the engine much more silent than it currently is..
nbk2000 Moderator	posted September 14, 1999 02:04 PM Why bother trying to silence it? A nazi buzzbomb was loud because it was big. It had to move a 1 ton object hundreds of miles. This little bugger is more than a hundred times smaller. Besides which, who the hell would think "RC camera guided buzzbomb coming to get me!" when they hear a faint buzzing in the distance? Maybe if these became popular weapons, I could see it. But not a one time thing. ------------------ "The knowledge that they fear is a weapon to be used against them." www.50megs.com/nbk2000
Ctrl-C unregistered	posted September 30, 1999 08:22 PM lol...i was just thinking...with all this IR search and destroy stuff...it would be quite fuuny if you spent thousands of dollars to make this heat seaking missle only to have it accidentally track YOU lol
nbk2000 Moderator	posted October 01, 1999 02:12 AM All the more reason to have a TV guidance system instead. Not much chance of you steering it into yourself. ------------------ "The knowledge that they fear is a weapon to be used against them." www.50megs.com/nbk2000
Bob's RAC A New Voice	posted October 19, 1999 01:17 AM I have looked at this idea with another for a few years, and have found that to reach any tracking capability from an optical device requires entity-based tracking. This requires multi-pixel sensors, such as CCD sensors. For a relatively low resolution sensor(640x480) with 8bit color depth, a bandwidth of greater than 2.5Mbit is necassary. The processors for a CCD sensor have to run between 10 and 30 Mhz depending on the sensor. Even if the processor was cached and ran at 1 Mhz, this is still in the genre of high speed circuit design. A bare minimum of 3 high priced IC's would be required: a Flash or RAM IC for a cache, a microprocessor, and an EEPROM for software or programable interface. I don't mean to seem condescending, but the caliber of these designs is far beyond the basic low speed logic systems that are produced from Radio Shack materials. I have nothing against the shack and visit it often, but not for a project such as this one. If anyone is still seriously interested in attempting to design a system, I would be more than happy to share my sources and more detailed findings. Much of the information is pulled from manufactuer's specifications(.pdf). One project that might be a good starting point is to researh the format of the signals being exported from the CCD's preprocessors and layout software to catalogue the dynamic patterns produced by the "target", as this is the heart of the design and costs nothing but time for mistakes. A more feasible alternative may be the use of three dimensional accelerometers on a stabilized board. The board may be stabilized efficently gyroscopically, as there is a more than ample pressure drop (Bernoulli's Principle) on the surface of an object moving at 100+ kph. Also, this design is implemented in the "g-force" meters used to measure a vehicles performance. I have one on my dash whose circuitry will fit in it's entirety inside a matchbox with room to spare. The relatively low bandwidth signal from the accelerometers can each be put through two sequential integrators with an output of displacement. If we all remember our physics classes, the integrals of acceleration and velocity with respect to time are velocity and displacement respectfully. An integrator can be made simply with an op-amp, readily obtainable and cost effective. This design does still require a cache, microprocessor, and memory setup, but as the bandwitdth is in the khz as opposed to the Mhz, the quality of the chips and tolerances of trace design may be more slack decreasing cost and development time. The programing is comparative simple. Some of the main issues are waypoint allocations, vector transformations, basic fluid mechanics, three dimensional path generation, and servo controll. This design is feasibly accomplishably by an amature with a large amount of spare time, unlimited funding, and a comprehensive understanding of digital circuit design. If anyone has any thoughts on the idea, or has researched it before, I would love to hear about it. Bob's Rent A Cow
nbk2000 Moderator	posted October 19, 1999 02:47 AM If your looking to make an autonomous TV guided missile, then you would have to go through all that. Simple TV transmitter and RC control removes all the heavy engineering otherwise required. Plus there's nothing like the personal touch. ------------------ "The knowledge that they fear is a weapon to be used against them." www.50megs.com/nbk2000
Bob's RAC A New Voice	posted October 19, 1999 04:20 AM For the practical route, video may be the way to go, as long as the craft is sufficiently slow. Most real aircraft fly high for a reason: if something goes wrong, they have time to react before they find a hard surface to make a mess on. As a guided projectile would either fly relatively low so that it would not eat up the range of the trancievers with altitude, or it would require a very powerful transmitter set. Given that the idea is to be economical, the low flying approach may be the better choice. Flying a craft through and around trees at high speeds is asking for trouble. The problem here is that lower speeds require a better design, because there is less stability at a low speed. I've heard that the most difficult maneuver for a pilot is holding the craft just above the stall speed. Of course, all of these inferences are situational and may not apply to any given application ------------------ Bob's Rent A Cow bobs_cow_rental@hotmail.com
Ho ju Moderator	posted October 20, 1999 03:48 PM i still think that a TOW (tube launched opticly sighted wire guided) type missle is the way to approach this. it is alot easier to guide something yourself than to go through all that shit. or if you do not want a long ass wire attached to your rocket use a transmiter. ------------------ Knowledge is power, power leads to corruption, corruption is a crime, crime doesn't pay. So if you know to much you will go broke!!

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