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Shutaro

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Shutaro last won the day on March 31 2015

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About Shutaro

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  1. It's hard to get a general consensus on things like this, a lot of people have strong opinions and there's not a lot of concrete data on failure rates or poorly built replicas. Everyone in my group agrees that cybergun is awful, but beyond that, most have opinions based on personal experiences, because this or that brand failed for them on the field or such. A lot of it comes down to just a roll of the dice, and without larger sample sizes it's really hard to know what's what these days.
  2. For general free-for-all, last-man-standing types of games, remember that while you may start alone, you don't have to play alone. For example, if you see two others before they see you, try to lead them into each other by throwing a rock or other method of making some noise where you aren't (ie. where the rock lands). Once you've got them to engage each other, stay hidden and wait. Take them both out, or take out the one remaining. Likewise, just because everyone else is your enemy doesn't mean you can't communicate or negotiate. Remember in WWII how we had to work with the Russians (our enemies) to defeat an even greater enemy at the time (the Nazis). So let's say you find yourself in a stalemate with another player, you're both aware of each other and neither has the advantage. You can fight it out (50/50 chance you will win) or you can think of the larger game. If you can negotiate a mutually agreeable settlement, ie. "we'll work together for now, and settle our differences later" then both of you just increased your chance of winning the larger game. Sure you will have to watch your back, but you have to do that anyways. I remember one game where we formed a similar alliance during a 4-way battle that would have inevitably ended as a loss for at least three of us. We even agreed that when only our alliance remained, we'd settle it with a game of Russian Roulette (using an airsoft revolver, of course). The fact we had four people kept everyone in line, each member knew that if he tried to backstab the group, even if he succeed it would be two versus one. We all survived to the end and while I didn't win, I had at least a 25% chance of winning which was better odds than had I done the lone wolf thing the whole game. If you want fun games, you have to structure your games with objectives and/or reward kills. When we do "every man for himself", we'll play games like 'freeze tag' (if hit you have to stop moving, freeze in place, and touching another player who is frozen converts him to your side). We don't do last-man-standing because that just results in a bunch of people camping all day.
  3. Have you tried measuring the voltage at the battery while pulling the trigger? Does it measure higher or does it also drop to ~2V?
  4. You should account for the starting current of the motor too, it's likely peaking a bit higher than the display is showing b'cos the display only updates so fast. And if you plan on holding the trigger a long time, firing continuosly, the heating of the motor / inefficiency will cause an increase. The actual current draw versus voltage depends on the setup. Too low of a voltage can cause the motor to stall or strain itself which will draw more current than when the motor is spinning at a good speed. Higher voltages may or may not affect current draw. In general, if the setup is torque-limited, it won't, but if it's power-limited, it will.
  5. Here it is only rumors (scare tactics) started by paintballers or others to try to drive up insurance costs or try to keep people away from the game. ie. "Did you hear about the guy in Florida who bought a real gun onto an airsoft field and shot three kids before they stopped him?" Fields won't permit it, and they would be fools if they did (insurance wouldn't allow it, for starters). Even things like actual knives or clubs aren't allowed on fields, there's just no reason for it. If you are playing in an area where you have to worry about dangers (animals, bandits, rebels, etc.) you probably shouldn't be playing there. There's too many things going on in an airsoft game to have to deal with the added problem of having to watch your back for real-life dangers.
  6. Modern day even without schematics or blueprints there are plenty of ways to do this, 3D scanners for instance. In the old days you could have made a reverse mold or just carefully measured and re-created. If there's a demand, people will figure out a way.
  7. Guges Mk3 I though the orange tips were federally mandated...
  8. ExFog, a lot of people think that, but the reality for a quadcopter or any type of helicopter craft -- when flying, there is a cone of suction above the blades. Anyone who knows what they are doing -- if they have the range, can start to lob bb's into this cone above the blades. The reverse pressure sucks the bb's right in... some will strike the blades themselves and others the upper body of the craft. So your best shot with a helicopter-type drone is to simply stay out of range. Other types like wings may prove much harder to hit, and generally resilient (until something important is hit).
  9. Know the federal laws as well as the local laws in the state you are shipping it to (just in case).
  10. You have to avoid things like that b'cos there's no datasheet, no specifications or anything like that. The problem with "resettable" fuses is that they just take too long to blow, 5-10 seconds isn't going to protect against a serious problem when you throw a LiPo battery into the mix. http://www.digikey.com/en/ptm/l/littelfuse-inc/fuseology-introduction-to-fuses/tutorial Here's a good search to start with. http://www.digikey.com/products/en/circuit-protection/fuses/139?k=fuse&k=&pkeyword=fuse&pv16=15540&pv16=15541&pv16=15542&pv16=15543&FV=fff4000a%2Cfff8003d%2C1c0002%2C1c0003%2C1c0006%2C1080017%2C1080018%2C1080021%2C1080088%2C10801b8%2C1f140000%2Cffe0008b&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25 If you LiPo is well specified, they will have both a continuous rating (ie. 20C), one or two burst ratings (ie. 40C for 5 seconds, 80C for 1 second), and a maximum current rating (ie. 100C). All these numbers should be considered... convert them to Amps. Whether you want 'fast' or 'slow' blow or something in between is going to depend on the specifics of your setup. If you have a smaller/weaker battery and a stronger motor, you might need to go with the fast blow fuses, but be ready for some experimentation as motors can often trip these when you don't expect it. 'fast' blow fuse family: http://www.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_mini_datasheet.pdf 'slow' blow fuse family: http://www.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_maxi_32v_datasheet.pdf Notice how if you exceed the rating 350%, the 'slow' blow fuse can take up to 7 seconds to blow, while the 'fast' blow won't last more than half a second. These are the two extremes, you'll most likely want something in between but it depends on the specifics of your battery and motor setup. The other thing to note is that the resistance is in m-ohms, ie. 1.95m-ohms which is roughly 0.002 ohms. An order of magnitude less than, say the 0.022 ohms mentioned above. Some polyfuses aren't that bad when it comes to resistance, ie. the one you originally linked to: http://www.littelfuse.com/~/media/electronics/datasheets/resettable_ptcs/littelfuse_ptc_radial_leaded_catalog_datasheet.pdf.pdf Even the maximum resistance of 0.0067 isn't awful, but what kills it for this application (LiPo battery protection) is that it takes 9 seconds to trip (when the current exceeds 70A).
  11. Motors have a 'stall' current that can be in the hundreds of amps. You can find this with some rudimentary calculations (ignore the inductance of the motor, just consider the resistance of the coils, brushes, etc. itself). Once the motor starts to turn, the current draw quickly drops due to switching and back-EMF. With a typical motor setup, the inductance of the motor's coils will limit the inrush current before it hits the stall current, since the motor will be turning by then. But in cases where there's a lot of rotary resistance on the shaft, you may see the current spike initially, until the motor is able to provide the torque to start the shaft rotation. In practice, the only time you may actually see the stall current is if the shaft is prevented from rotating (ie. seized motor), and the result will be a motor heating to the point of failure. In a typical "high-end" airsoft setup where your motor is drawing under 20 amps (average), 0.020-ohm resistance can account for 0.020*20 = 0.4V drop, which is around 5% of 7.4V. And if your inrush current is, say, 50A, it's even more significant (1V) in that initial stage where the motor starts to turn. For the same reason that switching to deans can affect motor performance, even seemingly insignificant resistances in the system can affect motor performance, especially at startup. I know airsoft hasn't really progressed to a lot of the motors we see in robotics, drones, vehicles, etc. (ie. still using brushed motors) where these become even more important, but the same fundamentals apply. Though most brushless, electronically controlled units don't run fuses for a number of reasons, you can still use them as a safety measure for brushed setups. Recommended, especially since there is a mechanical failure point. And don't use fuses that take even seconds to blow, one or two seconds on a seized shaft is all it takes to reach that stall current, and another second or two at that stall current is long enough to burn up the motor, melt or vaporize the insulation off your wires, and possibly cause a catastrophic battery failure.
  12. Most of the consumer drones you'd consider buying today can fly for 20-25 minutes. Not the ones you'd find in a toy store, I'm talking about the $500. range you'd get from DJI, Yuneec, others. Even the quad I used from years ago would do that. Flight time isn't such an issue as long as you have some extra batteries and a safe area to launch/recover from, you just land it, change out the battery, and take off again. If loss of coverage is an issue, have two quads instead of one. Getting more than 25 minutes of flight time is not easy, you have to get into the larger drones that are a bit on the expensive side. The problem is nowhere near as simple as you make it sound, the battery adds weight, and more weight means you need more thrust to stay in the air. An important thing to consider is the battery weight versus the weight of the quad without the battery. Once the battery is the majority of the weight, you're in an area of diminishing returns, adding more battery (weight) isn't going to be able to add a whole lot more to the flight time. You can get more than 30+ minutes but you need a different type of drone like a glider, and the pilot needs to do a decent job of flying it.
  13. Seriously, you're better off getting a dog (not a little one, the type you don't want to mess with). In theory, you might be able to pull off some kind of deception with a replica, but if someone breaks into your house, you're better off securing your family, calling the cops, and getting out. Many who break into houses expect the house is either unoccupied or people are sound asleep, and this type is likely to flee upon seeing you anyways. Being shot with an airsoft is only going to piss someone off, when I had this conversation before, the guy was like "I'll shoot them in eyes... blind them in both eyes", but in reality even that is a chancy thing at best. If you must fight (or decide to fight), there's probably plenty of more dangerous things in your house besides a replica weapon. Kitchen knives, chemicals, assorted furniture, etc.
  14. BTS555 is popular in Russia, which turns some Americans off towards it. Also $9 to $10 in small quantities which is a bit more expensive than a $3 MOSFET. And it's installed on the high (+V) side rather than the low side (GND). Which is actually easier the way must guns are wired up from the start, but not what people are used to for MOSFETs. But it really does live up to not needing any external components, I did one airsoft build with it and posted it here years ago, and I've measured the clamping effect on a scope, use it for other weapons (not airsoft) when it makes sense. http://ru.mouser.com/ProductDetail/Infineon-Technologies/BTS555-E3146/?qs=wK%252boHS4yu54MTa%2f39eglNA%3d%3d http://www.digikey.com/product-search/en?keywords=BTS555
  15. IGBT is a different beast, its best for much higher voltages than we're using in our guns. With a typical power IGBT, the collector to emitter voltage drop in the on state might be in the 1-2V range. This is insignificant in systems working with hundreds of volts (ie. 1:1 electric cars) but that would be a significant loss for the 7-16V batteries we're using. Same reason MOSFETs are preferred over BJTs. Even if wired correctly, a device driving a motor at 10A and dropping 1V across the collector/emitter path is dissipating significant energy (10W in my example). Whereas to source/drain voltage drop with a power MOSFET is generally insignificant, even at the voltages we use.
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