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My last mini machine gun

Discuss miniature cannons built from things such as pill bottles and pen caps.
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My last mini machine gun

Unread postAuthor: Spaderman17 » Sat Feb 08, 2014 3:34 am

Hello all,
I am French, and I speak very little English, sorry .....
I tinker small guns for my RC planes
My idea is to make aerial combat with the machine gun !
I registered on this forum, as discussions and ideas are interesting !




Soon

For those interested, the first prototype, but this one is less powerful!
I am preparing a new rotary model

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Last edited by jrrdw on Mon Feb 10, 2014 8:06 am, edited 2 times in total.
Reason: Fixed video.
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Re: My last mini machine gun

Unread postAuthor: jackssmirkingrevenge » Sat Feb 08, 2014 3:20 pm

Very interesting!

Reminds me of an old concept I had thought of, damn it must have been 2006...

Image

Does it work in a similar way? Some diagrams would be helpful.

Also, if this is being made for an aircraft, you are making it far too heavy... brass is certainly a bad idea, I would look more at delrin and aluminium.
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Re: My last mini machine gun

Unread postAuthor: Talk » Sat Feb 08, 2014 4:11 pm

How will you attach an air reservior with the rc plane and for aerial combat I think you'll need to attach a camera to your rc plane or you'll be wasting bbs for not being able to aim properly.

It'll be amaizing to create a sceneario like this with Rc planes.
25408_medium.jpg
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Re: My last mini machine gun

Unread postAuthor: jrrdw » Sat Feb 08, 2014 5:46 pm

As you fire the BB's the weight loose will move the center of gravity. How will you deal with the change midflight?
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Re: My last mini machine gun

Unread postAuthor: Spaderman17 » Sun Feb 09, 2014 2:04 am

jackssmirkingrevenge wrote:Very interesting!

Reminds me of an old concept I had thought of, damn it must have been 2006...
Does it work in a similar way? Some diagrams would be helpful.
Also, if this is being made for an aircraft, you are making it far too heavy... brass is certainly a bad idea, I would look more at delrin and aluminium.


I use brass for the first, and steel for the second.
This is a little heavier than aluminum, but the friction is best for this concept
I'm not too worried about the weight, the model weighs less than 200g and a plane 1.50m and 2.5 to 3.0kg. The "overload" will not be significant.

Some drawings and photos

Image

Image

Image

Image

Talk wrote:How will you attach an air reservior with the rc plane and for aerial combat I think you'll need to attach a camera to your rc plane or you'll be wasting bbs for not being able to aim properly.
It'll be amaizing to create a sceneario like this with Rc planes.
25408_medium.jpg


I currently work on the concept of the charger, but for the air supply, I use a butane cartridge 600cc empty.
I swell this compressed 12/15 bars air cartridge.
The video does not show the charger, I was just doing testing power and scope.
For shooting "flying", I used to do battle with banners ? (streamer?)I'm not sure of the translation !!

jrrdw wrote:As you fire the BB's the weight loose will move the center of gravity. How will you deal with the change midflight?


I think this is not a problem for 2 main reasons.
- I will try to ship only 100 to 200 beads 0.25
- I put the gun and charger near the center of gravity

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Re: My last mini machine gun

Unread postAuthor: jackssmirkingrevenge » Sun Feb 09, 2014 5:23 am

Awesome machining work I have to say, I think the design can be improved in terms of efficiency and I would shave off a lot more weight but if this is going on a large aircraft I suppose this is not a concern.

We have spoken about airborne guns in the past, for example: airsoft-pellet-guns/topic19506.html

My suggestion has always been something of the sort:

Image

The fuselage would be made of soft drink bottles which would also serve as the air reservoir. This could give you a massive volume (say 6000cc if you use two 3 litre bottles for the booms - ten times your current volume) at 10 bar.

You could also avoid using a hammer valve, this means you can use a smaller motor that simply has to drive a bolt, reducing weight and electricity consumption.

Image

Image
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Re: My last mini machine gun

Unread postAuthor: Spaderman17 » Sun Feb 09, 2014 6:02 am

I must say that your idea of the two fuselages with bottles is very good! I would not have dared this configuration!
Only two small engines and I get a very nice P38 ..... :bounce:

For my first prototype, I was just drawing to machining to check my concepts
I think make further improvements before putting a model on a plane ...

Your machine gun concept is interesting, but I think it may be difficult to get a perfect seal in the epoxy block. But it is true that your idea is lighter than mine!
Thank you advice and information ....
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Re: My last mini machine gun

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Re: My last mini machine gun

Unread postAuthor: jackssmirkingrevenge » Sun Feb 09, 2014 7:46 am

Spaderman17 wrote:I must say that your idea of the two fuselages with bottles is very good! I would not have dared this configuration!
Only two small engines and I get a very nice P38 ..... :bounce:


It makes sense to make the air reservoir part of the structure, after all this is the technique used in full size aircraft with a "réservoir structural"

For my first prototype, I was just drawing to machining to check my concepts
I think make further improvements before putting a model on a plane ...


Maybe my suggestions are a bit extreme in terms of efficiency but even though your prototypes are extremely well made, I think the design can be refined :)

Your machine gun concept is interesting, but I think it may be difficult to get a perfect seal in the epoxy block. But it is true that your idea is lighter than mine!


I made that drawing before I had a lathe and mill, these days I would definited have it machined with some o-rings thrown in:

airmg.png
airmg.png (12.2 KiB) Viewed 2643 times


There are a lot of different ideas for more efficient machineguns, you could for example have the BBs already inside the pressurized chamber.

Some of my "pet de cerveau" from the past: airsoft-pellet-guns/topic23240.html

Image

Also, you should really think about using Delrin (polyoxyméthylène), it's light, strong and durable, and very pleasant to machine.
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Re: My last mini machine gun

Unread postAuthor: Spaderman17 » Sun Feb 09, 2014 8:57 am

jackssmirkingrevenge wrote:Also, you should really think about using Delrin


yes I know Delrin, but for the moment I check the operation and cynématique of my projects .... The lighter material will come later ....
I like your idea with Oring seals, and I use things like that.
I made 2 styles "alternative" and my next project will probably be "rotatif"
I think there is less "parasitic drag"
and fewer moving parts! But it may be a mistake .... :idea:

Image

Image

Image

Image

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Re: My last mini machine gun

Unread postAuthor: jackssmirkingrevenge » Sun Feb 09, 2014 9:05 am

Nice!

I had thought of something similar here but without the separate valve:

Image

Didn't work out in my case, yours appears to have better prospects :)

It would be a good idea to make your valve counterbalanced, this greatly reduces the effort needed to open it. Have a look at Brian's CBHV:

Image
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Re: My last mini machine gun

Unread postAuthor: Spaderman17 » Sun Feb 09, 2014 10:22 am

I found interesting your link to reload, but I do not understand the design of the valve counterbalanced ?? :scratch:
Do you have any other drawings or explanations ?

I tried to make a balanced valve, but that does not give satisfactory results!

Image

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Re: My last mini machine gun

Unread postAuthor: jackssmirkingrevenge » Sun Feb 09, 2014 1:23 pm

The valve you made is not really balanced, have a look:

bv.png
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Re: My last mini machine gun

Unread postAuthor: sagthegreat » Sun Feb 09, 2014 2:32 pm

perhaps 2 of these 3000psi carbon fiber air tanks, used ones are pretty cheap on ebay, bout 30 bucks Image
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Re: My last mini machine gun

Unread postAuthor: Spaderman17 » Mon Feb 10, 2014 1:26 am

jackssmirkingrevenge wrote:The valve you made is not really balanced, have a look:

bv.png


Thank you for drawing, but I still do not understand the operation ... :scratch:
Is it possible to have a little explanation?
Excuse my ignorance .... :sad1:

sagthegreat wrote:perhaps 2 of these 3000psi carbon fiber air tanks, used ones are pretty cheap on ebay, bout 30 bucks Image


Thank you for the information, but it may be too big for my project ...

To answer Talk...
A friend who practice air combat on FPV
We are on the same forum, but I prefer the "shoot on sight"
The first time or it "down" an enemy !

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Last edited by jrrdw on Mon Feb 10, 2014 7:57 am, edited 2 times in total.
Reason: Double posting.
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Re: My last mini machine gun

Unread postAuthor: jackssmirkingrevenge » Mon Feb 10, 2014 7:28 am

As I said here, while your prototypes are really, really wonderful, I don't think they are ideal for aerial combat.

Look at modern aircraft guns, they don't go "dakka dakka dakka dakka" but rather they go "BRAAAAAAAAAAAAAAAAAAAAP!!!!"



This gives you a much greater chance of striking the enemy plane in a short engagement window.

My approach would be to make a simple cloud or vortex type BBMG, controlled by a small solenoid valve. I would then focus on maximizing on-board air capacity to give as much firing time as possible.
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