So myself and a group of fellow RC airplane enthusiasts are trying to probe the feasibility of a rather bizarre but excitingly titillating project.
You'll really need to open up your imagination here as this is really unconventional...
In the realm of large replica RC aircraft (wingspans in excess of 6ft), we're tossing around the idea of what it would take to create a small (<60cm length, <6cm diameter) IR or Optically guided Air-to-Air missile with limited tracking ability. (We'll start with a ground based version)
The idea is to create a replica AA missile built from similar materials as hobby rockets, and using small hobby rocket motors, that can be fired from one RC aircraft at another RC aircraft, track it, adjust the missiles course, then pop the parachute when the missile comes within 20m, give or take, to the aircraft denoting a successful 'kill'.
We have very low expectations of performance, but if we could even in the slightest, give the missile a hint of 'intelligence' to its flight path it would gloriously add to the realism of RC Fighter Aircraft.
At first this sounds really hard, but if you know how modern IR and optically guided missiles work, it seems 'possible' that something similar could be recreated with a small microcontroller, some spatial sensors, an ultra sonic sensor for proximity (to trigger the shoot), micro servos to controll the rocket fins, and some kind of object tracking sensor which would be the hardest part, and why I'm here looking for ideas.
This is not a BAE or Raytheon project and is ultimately being done solely for shits and giggles and pure theatrical sport. Expectations are low, but the budget is sound at about $500 per re-usable missile.
I've pondered the performance of a small CMOS camera to simply track the black object against the blue/white sky and compare frames to make course adjustments, but doubt the FPS performance would be adequate. The missile will boost for only 2-3 seconds before deploying it parachute by default. How far it travels will depend on the weight and drag of the final design, which are obviously yet to be determined. But we're shooting for a range of less than 75m.
The other option is again, CMOS type of camera, but one that can sense IR frequencies, and again track the 'enemy' craft using its engine thermal signature. These aircraft use Kerosine powered Turbine Jet engines which give off a substantial amount of heat (much like a full sized turbine jet engine).
Details of the internal working of the Fire Control System aside for a moment, the processing chain would work something like this:
1) Pilot aligns his aircraft with enemy craft, putting the viewing area of the missile on to the target aircraft
2) If the missile detects an object in its viewing area, it sends a signal to the microcontroller which sends a signal back to the pilots radio in the form of a audible tone. High tone for a 'lock', low tone for 'no-lock'
3) If the pilot gets a good lock and feels good about the shot, he triggers a switch on his remote which goes back to the plane commanding the FCS to initiate firing the missile
4) once the missile is launched its desired to 'track' the target as much or as long as possible before the rocket motor burns out and detonates the parachute charge (2-3 seconds), breaking the aerodynamics of the missile causing it to fall safely to the ground (much like any other hobby rocket)
5) if the rocket closes within a specified range of the target craft, it has to initial a self destruct mode (popping parachute) to prevent actual contact with the target craft
The only part I'm having a hard time with is the tracking sensor. What sensor could be small enough, and fast enough to meet this need?
Into the maths of it...
If a camera could capture 15fps, over the 3 seconds flight duration, it would only have to process 45frames (give or take). This should be enough, in theory, to track an object and adjust its navigation. But i really have no idea as I have no experience yet working with cameras with microcontrollers.
Lastly, it would be an AxonII powering the FCS (for an idea of processing capability), and most likely onboard the missile too (although we have concerns it may be too wide to fit).
The final option would be to find some kind of funky IR sensor that can see an area with resolution, as opposed to a single IR sensor used for distance.
Misc.
-Sunlight will be a factor - for good or for bad
- Lighter is better
- Less power = smaller batteries
- RADAR is not an option.