homebuilt missile

[Ctrl_C]

i brought this subject up 8 months ago and it was shot down. however, i think it has credence.

my idea first started with adapting a model rocket to have hinged fins controlled by servos so it could crudely be "steered". the only issue would be to keep the rocket from spinning (spiraling) so that the fins were consistant in the way they turned the body. i believe this can be done using a gyroscopic, inertial sensing system that is coordinated on a STAMP II microprocessor.

on further review, i realize that instead of custom fabricating high thrust engines to lift all of this, a cruise approach may be better. right now i am working on a jet engine composed of some sheet metal ducting and a turbocharger for a car to provide compression. i am aiming to get 150lbs of thrust. high thrust engines would still be needed for a boost phase, but then the turbofan would take over.

the only problem i forsee in this is the navigation system. i need a way to prevent the body from rolling. anybody have any ideas? i know military guidance systems use gyroscopes to detect inertial changes. anybody know how? the stinger missiles use a system like this and as you know, stingers are very small which leads me to believe they are not that complicated.

[nbk2000]

Stinger Missiles are as small as they are because they're highly comnplicated devices. They have custom made ICs, solid state gyros, IR seekers, computers, servos, special propellants, etc. It took them a long time to make them that small. And that's with the full resources of the governments labs. So I'd think missles are out.

But the cruise missle idea is feasible. There's plenty of information on the net about homemade jet engines and pulsejets. Then model airplanes are used, remotes are easily purchased. You can even buy GPS units for overlaying onto video (for steering into the target), and autopilots for them.

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[Anthony]

You can get both moving and solid state gyros from model shops (used in helis), they automatically adjust your servos to compensate for external movement to the model. They should be be able to stop your missile rolling.

I'd guess if you built this thing it'd take some practice to fly, things get kinda blurred when you attach jet engines to themhttp://theforum.virtualave.net/ubb/smilies/smile.gif

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Never underestimate the power of very stupid people in large groups.

[Donutty]

It would be pretty easy to create a remote-controlled missle which is simply a model jet plane loaded with HE. Could the engine of such a plane just be replaced by a solid fuel engine, and the electronics acting as a control system?

Or how about a 'Doodlebug' design - the daddy of the cruise missile! (a small un-manned propellor driven aircraft)

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...AAGH! It Burns!...

[10fingers]

I recently found out that it is illegal to make any type of rocket with a guidance system. Just in case you didn't know. Be careful where you test this.
Also, it is surprising that terrorists have not used something like a large remote controlled plane filled with explosives or poison gas to fly into a heavily populated area. Maybe they don't want to put any of their suicide pilots out of a work.

[EventHorizon]

Why invest in technology when all you have to do is tell some illiterate fool he'll have 72 virgins when he dies or some shit like that.

Has anyone seen those large scale bombers. They drop like gasoline or saltnpepper bombs.

Wouldn't it be fun to go to one of their get togethers and increase the level of realisim with some surface to air's. http://theforum.virtualave.net/ubb/smilies/biggrin.gif 'Course you better be fleet of foot cause they look rather expensive.

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"Chance favors a prepared mind" - Louis Pasteur
PGP ID 0x147CEF54

[Ctrl_C]

that RC heli servo/gyro suggestion was just what i was looking for.

[mark]

A very simple "missile" Would be a model rocket with spring wings. On the wings and fins are atatched servos. It could be flow like this: The rocket is launched into the air. Uppon reaching apachee the ejection charge deploys the spring wings. The rocket then free falls back to earth under your giudence. The problem with this is that it would have limited usses. Why do you want a guided missile anyway?

[kingspaz]

i'm sure estes make an RC rocket launched glider. the rocket shoots up and when the motor burns out the wings unfold and you have a glider!!
i just realised that would be kinda useless as weight is very important to gliders as in all RC aircraft so maybe it wasn't such a good idea...
maybe a large RC aircraft with a couple of lemonade bottle bombs. a slow flying aircraft is what you need. the sorta aircraft that have thick wings on the top. like large trainer aircraft. they can be easily modified without much hasle. you could probably get away with only one extra servo being needed.

[FadeToBlackened]

If you wanted to go very slow, a triplane, like the Red Baron flew, would be the design of choice. There is more wing area, so you dont need to go as fast.

[BoB-]

The amount of explosive a RC plane would carry is small, and probably wouldnt create any major structural damagem, shaped/tamped charges, and incendiary's would be better suited.

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Teamwork is essential.
It lets you to blame someone else.

[mark]

My idea of guidence is using the stick that comes with the launch pad. It worked perfectly, flying straight as an arrow before setting op the AP payload. 1/4 of a filmcanister 1000 feet in the air makes for a meaty pop. I know this dosnt help you but I felt like sharing one of my misadventures.

[Bitter]

The fins on the missile must not move more than a few degrees- I have seen mach 2 air to air missiles being manufactured and their fins only move about 3mm. Of course, a slower missile would be easier shoot down, but easier for the controller to hit his target.


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"Death should not be rushed; one should savour it like fine wine and enjoy its aroma, but if in consideration of your impatience I must kill you now, then so be it..."

[Ctrl_C]

well im not planning on going to war or anything, its more of just a backyard see if i can actually do it type thing. set up a target 1/4 mile away from launch and see if i can program it to hit it. thats all

[nbk2000]

Speaking of war, we're still waiting for the nuke book you promised to upload to the forum FTP. Where is it?

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[Ctrl_C]

speaking of nuke books, i've been waiting for someone to tell me how to do it in a pdf? where is it? http://theforum.virtualave.net/ubb/smilies/smile.gif

[ronald]

Speaking of guided missiles... Not all of those commercialy available gyros can work with rockets, because the turn rate the gyros can follow is usually limited and the rocket may go to a spin or when altering rockets course with fins on high speed, the turn rate is quite big. Ive seen most of those solid-state gyros with max turn rate 180 degrees/sec. I think for rockets, that is not enough.
For just a cool experiment, where you want to drop some kind of package on a target, i would fly the "warhead" up with a rocket and then guide it to its target with a simple paraschute by making the cords shorter or longer. Just 2 servos would be enough for the job. For just a simple test at night, you'll create a very bright spot on the ground, there will be some(4 should be enough) light sensors on the bottom of the "warhead" and you'd guide it to the direction, where more light comes. All of it can even be done with analog electronics so you dont have to mess with microcontrollers(why are you so obsessed with the basic stamp anyway? would for example an AVR or PIC do the job?) and code. The experiment has to be done in total darkness and there has to be no other light around.
To make the stuff more useful, you should use a light(laser?) modulated(on-off) at a certain frequency and the sensors on the "warhead" would send their stuff through some kind of band-pass filter.
This is just my theory...

[Cyclonite]

I cant think of any reasons good enough to destroy a decent amount of expensive electronics with a small charge. But if you have cash to burn it would be a nice project. Id have to go with a modified RC plane with a charge of some sort, that seems to be the most feasible route.

[TRUTHSEEKER]

Check out:

http://ukrocketman.com/rocketry/guidance.shtml

and

http://ukrocketman.com/rocketry/gimbal.shtml

The whole site is packed with info and should point you in the right direction.

[Bert]

A simple device to keep a rocket from rolling is the "rolleron".

Two opposite fins have a small aeleron type flap at the back outside corner turning on a damped pivot. Built into the flap is a toothed wheel arranged so the slip stream hits the edge of the wheel and spins it, once it comes up to speed it functions as a gyro. Any rolling, the flap is swung into the slip stream and corrects the roll. For ground launch, you will need to spin up the gyro with compressed gas before launch (in aerial applications, the speed of the plane keeps the wheel spun up if the plane is airborne). I've seen these devices fabricated and used in large amateur high power rockets intended to carry a video camera.

This technology was developed for the venerable sidewinder missile... Back in the stone age. Microprocessors aren't allways the best or easiest control system.

The FAA will be VERY upset with you if you install an active guidance system of any kind in a rocket, most particularly one with an explosive payload. They put the kibosh on this years ago, even before Sept. 11th.

[Jacks Complete]

Something I realised years ago is that KISS is a good idea.

With just two lines of code you can program an X to chase your mouse cursor. This can be done with a few bits of electronics, too. A BASIC Stamp is far too expensive, for a one-shot. After all, the US can only just afford a million dollars per cruise missile, and got the new ones made for just $300K a shot, what chance do we have? The only advantage to all that cost and power is if you are shooting at countermeasures or something that is fast moving. If you are going to do that, use a radio set with servos, and perhaps use a camera, and guide it yourself.

Anyway... Early homing missiles used a device called a quadrant detector. It simply has four areas and a lens, and anything that shines on it will trigger one or more areas. A simple circuit will let you wire a servo such that it automatically centers, and so it will play follow the point from two opposing sensor segments. Two of these will chase the light in two axes. They are expensive and hard-to-find (though a link NBK provided gave me a good lead) however there are now simple robots (light seekers) available in kit form, which will drive a pair of motors so that they seek light, or dark. There is a page here. (http://metallica999.freeyellow.com/rgs/rgs.htm)

For a simple seeker, wait till night, shine a laser spot on your target, and fire. You could put it on the back, and make a beam rider! (Harder to jam)

The kits are about £15 each, and you will need two.

A different approach was the spinning sensor. This one used the spin of the missile head to scan the area ahead, and used just one sensor and one control. I am trying to find a decent link but can't. Basically, it spun a mirror at speed, and scanned the target like that. Obviously, you could do away with the mirror, and spin the missile instead, and adapt the steering. However, your servos will be required to react very quickly unless your rotation is slow, and if your rotation is slow, you would find it harder to track something.

Check out the little light seeking (Photovore) robots as a first step. There are loads of links on google.

[ronald]

I searched about that rolleron stuff and found this doc : http://naca.larc.nasa.gov/reports/1955/naca-rm-l55c22/naca-rm-l55c22.pdf

A video of some test with rolleron : http://psas.pdx.edu/psas/Resources/Movies/RolleronLcomp.mpg

Just in case anyone is interested...

[jimmyboy]

what exactly is your rocket being designed for? there simply 2 types cruise (surface to surface) and SAM's -- both would need their own set of specialized gyros and electronics but the cruise would be much easier (no need for guidance - aim and shoot) The best i think you could hope from a homemade missle is 50 foot or so - making it go straight would be the biggest problem -- why not use a model car with some HE attached to it (makes me think of the deadpool) -- you could invert a rifle/SG shell and glue a bb on it to make a detonating tip

[Yorki_pyro]

Is there a home expedient way to make a quadrant detector? Perhaps with photodiodes or something?

[Unknown]

You beat me to it Bert. I have also heard those spinning wheels called "spinnerettes". I've seen pictures of sidewinder missiles with the "rollerons" in the tips of the rear fins.

[Cyclo_Knight]

I'm confused...why spend several hundred dollars to build a cruise type missle only to blow it up. Seems like a helluva waste to me. If i were you, stack up some haybales 20 feet wide, 10 feet high, and 5 feet deep to minimise damage to the sensitive(and expensive) components.

If you construct a crumple zone, and protect the main-body, there is no reason why you could not use this dozens of times. Use heavy aluminum for the body and an entirely seperate lighter aluminum for the front 18 inches. If you properly score the crumple zone, you should be able to avoid almost any damage to the main body.

Another good idea would be to allow the wings to break away safely in the event of an uneven landing. This would prevent damage to your servos if your wings were torn away.

A major worry would be protecting your most sensitive electronics. I reccomend sealing all main sysyems in seperate enclosures, filled with shock-absorbing epoxy resin. This will make it impossible to repair, however, if one of your systems is irreperably damaged you will only need to replace that one enclosure. This will also help contain any damage.

Question: Were you planning on using a solid-state booster -> Turbofan or a simpler 02/Kerosene Rocket

If You are planning a O2/Ker. then I have plans for you on active thrust vectoring nozzles for liquid- rockets. The only problem is that the necessary ceramics are very expensive. Since you are only doing very short runs though, You may be able to use a cheaper tigh-temp metal alloy.

[wrench352]

Cyclo Knight,thats alot of hay or straw (100+ bales by my estimate). I'd use volleyball nets, it would be cheaper, easier and easier on the missle itself. Isnt that what "the pros" would use?

[PsYcHo]

Just a little bit of advice about flying this, from my experience with my RC aeroplane, it is very hard to fly, even though it is a trainer. I haven't managed a flight where it hasn't crashed ;) Considering this is a very slow model, controlling a fast moving missile manually will be very difficult. Although it could just be me that is useless at flying it...just a thought worth considering.

[simply RED]

I have some homies from the bulgarian army who are able to pass "maljutka"(1st generation manula controlable missile) through a window.....
If the personal is trained, no problem could occure!!!...

[nbk2000]

The netting used by golf courses and paintball fields would seem better suited, as they have LARGE nets that allow for a lot of leeway.

In fact, fuck buying your own nets, just use the nets at a golf course for your own use...at night, and one time only, of course. ;)

[Cyclo_Knight]

Yeah...i didn't think that through i guess. Still, A missle moving at 700 mph is not going to be slowed down by any nets. I just had a new idea though.

Instead of trying to slow the mossle down or stop it, why not simply shoot for a moderately controlled landing. My idea is this: A pair of small drogue chutes deploying automatically on engine cutout slow the missile to landing speed. The crash area could be a local small lake at least 1/2 mile long to cushion the landing. Although the wings would probably be ripped off, the double chute design might help to prevent rotation at low speeds.

Recovery could be greatly facilitated by a pulsing radio beacon to guide you and your dinghy to the site. Visual sighting probability could be increased by using a neon or light-gathering paint on the rocket body. Although this could increase the danger of bystander sighting, if you have the resources to complete this then you probably also have a car. There are thousands of small local lakes all over the country, so unless you live in the Gobi desert finding one with few locals should not pose a great difficulty.

In addition if you really didnt want to get wet, you could remotely or automatically deploy self-inflating floats to bring your baby to the surface.

-peace all and merry cruizin :D

EDIT: i just thought of this...the forces exerted on the chutes at nearly mach would be tremendous. I gess you could either go with reverse thrusters (Star-Trek style) or (obviously) a multi-stage chute design to slow the deceleration. However the clincher would be making sure that the timing was such that all stages would be fully deployed before water contact.