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jagdtiger00 posted:7. gently caress this kid- http://www.youtube.com/watch?v=JHJs1gBLiuQ&feature=related  jesus loving whatThat level of wankery aside though, I keep seeing helicopters flying inverted, how is that possible? I understand that higher end helis allow you to change rotor blade pitch, but can they actually be reversed? It looks like the kid was twisting his control sticks to adjust something, is that the rotor pitch? I've kind of just recently discovered how cheap this stuff has gotten, and it is awesome. It's like all of my childhood dreams are coming true for a couple hundred dollars. Since there was some talk of ethics in here, should I feel bad about attempting to mount the innards of an airsoft gun in an RC plane? I have to admit the thought of FPV dogfights make me more than a little giddy...
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Apr 15, 2011 11:28
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| # ¿ May 2, 2024 06:42 |
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I had some circuit boards printed for the airsoft trigger circuits, but just before they arrived, I crashed both of my jets pretty much beyond repair. They were just foamies so it's not a big deal, but now I won't have anything to fly the gun on for a while  Because of the weight I'm not sure I could fly metal BBs, but I'm sure they'd have more energy downrange than plastic. Since I'm not really familiar with airsoft, does anyone know if there are magazines more reliable than gravity feed that have a fairly high capacity? Do they make spring loaded helical ones?I had considered rockets too, but I think without any sort of guidance, all I would accomplish is starting brush fires in unpredictable locations. Just for the hell of it, I even put some thought into what it would take to build a guided missile--I figure you'd have to track acoustically, meaning a microprocessor, multiple microphones, power source and tiny servos... a major engineering project on its own. Would be loving awesome though, even if it just tracked and didn't explode. Anyway on the less destructive side, I've got a bunch of ideas for autopilot systems using GPS, gyros, accelerometers and such. I'm thinking functions like automatically holding altitude/heading, flying between waypoints, circling a location, maybe surveying an area for girls with a downward-pointed camera. What would be especially cool is to combine all that stuff with an FPV on-screen display for pretty much a full instrument readout. I figure this has been done already, but like half the fun for me is designing and building it on my own. Now that the semester's ending, I might finally have time to try some of this stuff.
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Apr 29, 2011 11:30
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Reliable feeding is definitely a priority over high capacity, so if 100 rounds is all I get, it'll have to do. Older planes did have unguided rockets (as do modern helicopters, which someone mentioned), so it's not that far-fetched. I just had another idea: what if you could integrate a gun sight into an on-screen display? One that would compensate for target lead time and gravity based on your own speed and orientation, and possibly with a convergence setting if you have multiple guns. Screw historical accuracy, I think that would rule (though to be fair you can't really have tracer BBs unless you get glow in the dark ones, and fight at night)
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May 3, 2011 08:43
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What is RC for if not acting out my childish fantasies?  Okay, so I consider myself a decent EE, but RF consistently blows my loving mind. I was reading a bit about that skew-plane wheel antenna--is it omni in a sphere pattern or just a hemisphere? My FPV gear just came in, and I'm going to be mounting it on an airplane rather than a helicopter, so if I could still do loops and barrel rolls and stuff without losing reception, that would be rad. What exactly is the benefit of that over a straight antenna?
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May 4, 2011 00:02
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This RF stuff is finally starting to make a bit more sense, thanks for that link Vitamin J. This video helped a lot, too (holy poo poo that guy is a CAD wizard). Just for the hell of it, I decided to try my hand at making a couple of these antennas: Skew-plane wheel at 2.4 GHz - With this on my 1W transmitter and an 11dBi rubber duck on the receiver, I got out to about 300m in my apartment complex, which is full of trees and hills and wifi. At some point I'll test it at the field where there will be less of all of those.  5-turn helical at 2.4 GHz (work in progress) - was reading about antenna trackers, and now I have this compulsion to build one.  Speaking of transmitters, does anyone know anything about this transmitter from hobbyking? Given the channels in the "tx spec" section, I'm worried some channels might be outside the 2.4G band, and I don't want any black trucks pulling up at my field... flick3r posted:the size and scale of the package would be (I think) A bit too large to pack onto a small RC. But would be a better size package to pack on a small to mid size robot chasis But the point is for it to fly! I may have forgotten to mention that I'm talking about taking the guts out of an airsoft gun, not mounting a whole gun on the plane. The motor + gearbox I have weighs only 130g, and the barrel is a thin aluminum tube which could probably be cut down. Getting everything to fit together without the full gun housing might require some custom parts, so I'm looking into that as well. I'm willing to bet the whole thing would fly on a larger parkflyer without much trouble, maybe at the cost of a smaller battery. But yeah, if modifying a stock plane doesn't work so well, I could definitely look into making a custom airframe. Is it possible to buy big solid blocks of EPS/EPO/some other kind of foam that I could cut?
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May 7, 2011 01:12
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flick3r posted:But the targeting program is more of what I was talking about when figuring in the heavier part of the package. I don't exactly know how much more gear you'd need to put on the airplane to allow for all of that, but I know it would be considerably more than just the gun part. The microprocessor and accelerometer breakout that I was planning to use are really tiny--I just measured 7 grams combined--and can run on the plane's main battery. From what I've read, I might need another processor entirely dedicated to generating the OSD signal, maybe a gyro or two as well, but in general I'm considering that stuff to be negligible compared to the gun and FPV weight. And while it might be an interesting additional step to take, I wasn't planning to put the gun on a pan/tilt mount or anything. Helldesk posted:With 1000 mW (a whole freaking watt!) of radiated power from that puppy you probably need a license anyway. Unlicensed ISM band use is limited to 100 mW EIRP in most countries (but just 10 mW in the UK, for example). Check your country's regulations before operating such hardware. 1 watt is a lot of RF power? I'm in the US, and most of the information I can find about the 2.4 GHz band pertains to wireless networking (obviously). I came across these tables in a few different places, but I'm not sure I understand the difference between "point to multipoint" and "point to point". Either way, it looks like I'm okay up to 4 watts radiated isotropically; help me out if I'm misunderstanding that. Also, is it really that as bad as I'm hearing to operate both your control and FPV systems in the same frequency band? It seems like as long as they're in different channels it should be fine--they work simultaneously for me at close range, but I guess I could see the out-of-channel noise being a problem if your control signal is already weak at some distance.
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May 9, 2011 10:11
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So I may have misunderstood something about servo control signals--I had thought it was an analog voltage, just based on my multimeter, but I've read a couple of places that it's actually PWM, is that right? Is there a standard mapping between pulse width and servo position? Would it suffice just to throw an RC filter on that line to turn it into an analog voltage? Even so, the voltage is really low (a couple hundred millivolts) and is below the dropout voltage of the op amp I had planned to use; I may have to buy some rail-to-rail op amps to make the gun trigger work. In the meantime, a couple things I feel like sharing for no good reason: I got this pan/tilt mount in from servocity.com which seems pretty solid, but standard servos are waaay larger than I expected. I don't know if I'll be able to fly it on either of my planes at the moment due to the weight. Anyway this was my first order with them and I just want to say what a great company - not only did they give me better servos than I ordered for free, they sent candy in the package too    And I found that I had the parts laying around to give my little AT-6 some navigation lights (the diffusers are nylon bolts and nuts), which may or may not help me keep from losing track of the plane's orientation at a distance - probably the biggest cause of crashes for me so far. At the very least it'll look neat when I fly at dusk.   Edit: Also some old HAM dude was telling me that RF can damage your eyes at a certain power level, even if it's not ionizing radiation. Is this guy loving crazy or should I actually be careful? I was under the impression that unless the radiation is ionizing, the only danger is from heat.
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May 13, 2011 04:50
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ante posted:Servos are just DC motors with negative feedback to make the motor go to a certain position as fast as possible with critical damping (as little slow-down or overshoot as possible). Basically the motor feeds positional and velocity feedback into its input, and you don't want to mess with that if you don't know what you're doing. The term PWM doesn't apply here. I didn't mean the feedback internal to the servo, I'm pretty familiar with how that works. I mean the position command sent from the receiver. This page for example describes a pulse width of 1500us representing neutral, while 600us is -90º and 2400us is +90. Is something like that fairly standard?
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May 13, 2011 06:02
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Ah, no, I'm sort of doing multiple things at once here. The antenna is for the FPV feed and has nothing to do with control. I'm sure I haven't been clear about it; I have a bad habit of doing things first and trying to document them later. What I've got is the gearbox and DC motor from an automatic airsoft rifle, and my plan was to hijack a spare tx/rx channel to send the on/off command to a power MOSFET to drive the motor. On the transmitter end, I'd wire up a momentary button and some resistors to send one of two position commands (doesn't really matter which, but they should be well separated) to represent "fire gun" or "don't fire". On the receiving end, I've built a circuit to try to interpret the signal on that channel, originally intended for a servo, and turn it into the gate drive signal for the FET. I'm not trying to PWM that transistor or anything, solid on/off is fine, but I think I've misunderstood what the signal coming off of my receiver looks like. I designed the circuit for an analog voltage, I think 150-300mV, but it looks like it's a variable-width digital pulse instead. I've opened up a couple of analog servos and I think they just lowpass filter that signal before feeding it to the controller IC for the position command, but I might be wrong. Digital servos would measure the width of the pulse directly, I guess? That would certainly make them more noise immune. Edit: Okay I was lazy before but I finally just scoped it - my receiver puts out a 3.6v digital signal at 45.5 Hz, with pulse widths varying from about 1-2ms. RC lowpass should do what I want it to. elektroboot fucked around with this message at 07:46 on May 13, 2011 |
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May 13, 2011 07:23
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| # ¿ May 2, 2024 06:42 |
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helno posted:http://vimeo.com/22280110 Man, that's pretty rad. What is the kk board, some kind of controller for stability? Is it even possible to fly a quadcopter without a controller like that?
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May 24, 2011 05:34
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