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JSR, take a look at this page, at the bottom there is a link to 'how-to'. Under cannons there are a few pages that may be helpful with your project.
Here's a pic of a system from http://bb_ops.tripod.com/RC_Combat/RC_Combat.htm
I tried this successfully, but I modified it and put the oring breach on the interrupter. In your case, you may want to eliminate the interrupter and use a coil to hold all your bb's. Place the O-ring breach at a point just opposite from where the interrupter pin is and eliminate the pin.
I really want to focus on accuracy, this thing is capable of much better accuracy than you guys are seeing. I am concerned with rifling of the barrel. When properly aligned with my targeting display it will be like firing the gun through a digital sight with 10x optical zoom.
I will probably be firing semi-auto or 3 round bursts, I do not at all need to carry more than 30 lead BBs at a time.
A powerful, precise semi-auto Co2 gun is going to do more damage to a target than the lower pressure full-auto vortex or cloud chamber in this application, There's absolutely no need to "draw a line" I can hit a target with the first shot. The cross-hairs on my OSD combined with the option of 10x optical zoom will give me great accuracy.
The drozd's firing circuit is very compatible with the electronics I already have...
It makes no sense to use a lower PSI, onboard this aircraft, I need to pack as much power into the smallest amount of space possible. The structure of my airframe is all carbon fiber and is sheeted in fiberglass, using the air-tank as a structural member does not make sense and it may not hold up in high-G maneuvers and hard landings, plus the weight savings wouldn't be significant when replacing the carbon fiber.
I'm not as concerned with weight as much as with the space available inside the fuselage. I don't have the room for a large air tank and cloud chamber in any of my current airframes.
When I think of cloud or vortex BBMGs, I think of low precision, inconsistent firing, lots of wasted air, extremely high rate of fire (for a short while), and most of the time relatively low velocity.
When I think of a semi-auto co2-electric solenoid actuated hammer-valve rifle, I think of a gun that is extremely efficient with co2, very precise, very powerful, more compact than a cloud, and much easier to fire electronically.
I mostly don't feel like doing a whole lot of scratch building, I have a super precise and aerobatic FPV airframe which I'd like to install the auto-cannon.
Accuracy isn't going to be great with BBs. Rifling the barrel (If I remember correctly) doesn't significantly improve the accuracy of spherical projectiles. I think you'd be better off with a hop-up system similar to what is used in airsoft, if you are intent on using BBs.
I wonder how much deeper the ocean would be without sponges.
Right now I'm having amnesia and deja vu at the same time. I think I've forgotten this before.
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These designs have been notedfor years now, however now that you point it out its annoyingly similar to the sort of things I'm working on at the moment
If it didn't it would have been forgotten about, cylindrical projectiles came about much later than rifling did
Appreciated, perhaps since few here have similar experience with FPV flying we're finding it hard to understand how easy these things might be to aim.
A few points:
- accurate on the ground does not necessarily mean accurate from the air, it would be interesting to mount the gun on the plane and run the engines on the ground while keeping the aircraft static, and see if it really still fires in a straight line as opposed to a cone.
- CO<sub>2</sub> is a very temperamental gas that's very sensitive to temperature changes, surely being flown around isn't quite going to help it keep a constant pressure
- How do you plan on accounting for windage and projectile drop? The way I see it, you can't really talk about accuracy in these circumstances. I think the only way to reliably hit a target is to fly directly at it till you're 5 yards or less away from it, fire and pull away at the last second.
Granted, going with an air tank as a fuselage would involve more work than simply fitting a ready made gun to an existing airframe. My biggest concern would be weight, I think this will add at least 500 grams and this translates into a higher wing loading which in turn makes your plane harder to control at low speeds which would then negate your accuracy advantages.
For most amateur BBMGs, this holds true, however there are ways of optimising your design to get maximum power and efficiency with a bit of careful design and R&D, though since you're not willing to make this effort we should stop bleating on about...
In terms of compactness, efficiency and ease of electronic firing I would agree however I don't think power is significantly greater and in the circumstances, precision isn't either.
If you're intent on going with the Drozd, first step is to take the risk and buy one and see how much weight you can shave off. Try and do it in a reversible manner so at least if it doesn't work in flight you still have an auto BB gun
If your accuracy is really that good then an accurate burst would be best.0
Spherical ammo isn't very accurate unless you have a hopup.
You could also look into single shot, designs. Simple and powerful. Eliminating the loading mechanism makes it much easier to use darts or pellets. Way more accurate (and possibly more powerful) then spheres.
Maybe use a buckshot if you want to hit the target easily.
I that thought too. On top of that, are there any delays in the the video feed or the RC firing system?
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There's an idea, you could make something like the Gerät 104
You could easily fit a big bore single shot combustion loaded with buckshot, you could slim down barrel and chamber construction and some aerobatics before would ensure a proper mix it could just be a single tube like the German prototype above, with countershot at the rear and the fuel mix between that and the projectile.
Here's a video of a non-FPV rocket launch I did earlier today.
I posted in this forum too:
in response to this:
There are plenty of dead VC who will attest otherwise
They were used by Vietnamese and Laotian forces on combat missions in south east asia, also by the French in Algeria, carrying rockets, bombs, gun pods and napalm.
When I saw those videos, I damn near creamed myself. This is exactly the kind of thing I have been looking for for nearly three years. Exactly. For a while, I would spend time making drawings of my cannon designs, and more than half of them (surprisingly) tended to be more related to R/C aircraft. One concept in particular was for an IR guided surface to air missile. The others were mainly concepts for a large, home built close air support bird. One of the biggest problems I found was trying to find a good type of gun armament. Cutting down a Drozd to the bare essentials seems like a better idea than what I had for your purposes. The best I came up with was taking two airsoft minis and cutting them down to the mechanism, batteries, and barrels, and a compact vortex gun. Then again, mine would be used for hitting people on the ground and softening up defensive positions. Vortex and cloud BBMG's are simply far out of the question, due to GROSS INACCURACY and weight (remember guys, the best of our vortex guns can't even land a 6' group at 30'.), unless you use 6 cut down minis (my main design for guns only loadout would have relied on two chin mounted guns and four in dual wind pods). My design would have actually been able to carry a vortex gun, since it had a nominal wingspan of around 3.5' IIRC. But that's still too heavy for too little. You ought to go with the drozd.
I still haven't come up with a suitable substitute, rocket rails seem like the best idea so far.
What's the nominal price of such a plane? If I get enough interest, I might be able to build one of my own airframe designs and add on the guts. I design mine to be very easy to fly, plenty of wing area and mass to them to avoid getting too tossed around in the wind, also so they handle a bit more gently. I haven't been able to build a single one yet though. I graduate next year, so I might have the time.
This is kind of delving from the drozd concept but, could you not just have a couple of hybrid cartridges as the armament?
Last edited by irisher on Sat Jan 02, 2010 11:35 pm, edited 1 time in total.
That would be both overkill and dangerous.
That sounds like good enough justification for any project
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I only skimmed over this entire thread, but I honestly cannot see a Drozd, which I own, being used in a model plane. Even if you cut it down to the bare bones, you are only taking off some plastic/polymer which doesn't weigh a whole lot in the first place. The entire weapon, other than the polymer parts, is firearms grade solid steel. The whole thing is over-engineered and has a bit of heft to it for the size. Also, unless the plane is counterbalanced (meaning a whole lot more weight) the Drozd will definitely affect the plane negatively. In place of counter balancing, the drozd could be placed off to one side.
The only thing I can see being removed is the polymer surrounding the barrel and circuit board area as well as the cover for the solenoid. I suppose the polymer surrounding the magazine could also be cut down, but it cannot be removed otherwise the magazine will likely not properly align with the breech and stay in place. Whatever parts of the drozd are removed, the basic frame (at least the rear half) must remain intact.
Any other questions, let me know. I will try to get back to them, but I can't make any promises.
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