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Post by aldenlulamoon on Jan 18, 2015 23:32:52 GMT -5
Originally I wanted to build a tank for use in airsoft... I still plan to, but I figured my local field wouldn't go for that idea, SO... I decided to make an artillery piece instead. When I asked what kind of damage an airsoft howitzer would do, the field staff told me that a nerf vortex football launched from a howitzer would have a kill radius of 25 feet. I then set to work making the piece. I built it with wood, and PVC pipe. The barrel has a bore of 2 inches (which rounds up to about 51mm. We'll call it 50mm, for historical purposes.) And is powered by a pressurized air tank in the back of the gun. My original design was breech loading and used 40mm airsoft grenade shells as a propellant. This proved too inefficient and ineffective. So, I decided to build more of a traditional "potato gun." The 'trigger' is a 2 inch ball valve that I plan to tie a lanyard on so that it opens faster when pulled. The gun is now finished, and it's a very simple design. Muzzle loading, with the ability to change out barrel lengths, or even reduce it to a smaller bore for launching other projectiles. My next step is to get the mount finished. the BASE is pretty much done, and it just needs the wheels, elevation mechanism, paint, and the shield. When put together, I'll take pictures and post them. Currently waiting for the PVC cement to dry. NOW. the reason I made this thread. Does anyone know a good way to "accurately" put rounds on target with one of these things? I know it'll involve a bit of math, but I was wondering if anyone knows anything about how the actual sights for AT guns and such work, and how difficult it would be to build one for my purposes. It would probably help to have some numbers, like how far it shoots certain projectiles, etc. So I'll post those once I test them. Thanks! -Alden
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ScottCollins
Private 1st Class
A people that values its privileges above its principles soon loses both.
Posts: 548
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Post by ScottCollins on Jan 19, 2015 20:13:43 GMT -5
Funnily enough LSSAH and I were just talking about this at the game this weekend. What I'd do is make a base that has degrees 90, 45, and 0. Test fire the gun at 45° and record how far with went. Then continue that practice for different angles. Get a map of the field and mark your position, then make a grid on the map and also include a scale. With all that info you should be able to semi accurately put rounds on target depending on the wind direction and strength
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Post by aldenlulamoon on Jan 19, 2015 21:36:53 GMT -5
thanks Primarily we'd be doing direct line of sight firing (like accross a field, into a creek bed, etc...) but it'll be helpful to know how to do indirect fire.
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Post by insterburger on Jan 19, 2015 21:58:53 GMT -5
I've done a smaller version on the same principle that has been used both for indirect fire (as a mortar) and direct fire (as a Panzerschreck or bazooka).
Working on the assumption that a full-size Nerf Vortex will act similarly to a min-vortex, I would say that indirect fire will probably treat you better. When used as direct-fire, the round had less accuracy than when shooting up in the air, and a LOT less range, but that's my experience. Even direct fire will require considerable elevation to put your rounds on-target.
I would riff off of Scott Collins' proposal and take it one step further. Build a simple artillery sight that moves with the barrel elevation, test fire the gun at various elevations (somewhere flat and windless) and mark off your sights for a variety of distances based on measurements of how far your Vortex goes each time. Then in the field where elevation and wind come into play, estimate up or down as needed.
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2nd Bat
Master sergeant
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Post by 2nd Bat on Jan 20, 2015 17:39:36 GMT -5
For added realism and accuracy use aiming stakes placed around your mortar position these can be placed on alignments specific to preplotted targets. Gradiant lines on the stakes can have presets for angle and elevation greatly improving your consistancy for quickly putting your rounds on target. Practice in order to learn how to adjust effectively from those target reference points. (" DROP 25, RIGHT 25"). In reality most mortars were directed with eyes on the target but heavy mortars and artillery were seldom fired where the gunners were watching rounds hit. In thoses cases spotters called in fire missions and adjusted fire by radio or field phone.
This can be practiced in a training setting in full impressions using realistic radios and make for a fun event day for even a small group of players. Stakes typically had graphics at assorted heights on the stakes and the piece had an optic device and "bubble for level" to insure precise alignment. At ground zero airsoft in Conn Big Ed had about a dozen pre established target reference points and was masterful at adjusting from each with radio instructions. I even saw a round bounce off a players head which was extremely impressive shooting from 400 meters away!
Incidently he soaked his rounds in chem light sauce when firing at nightand it was extremely impressive to watch. We played with a 20 foot kill radius soif the round ht within 10 feet of you without a wall or obstruction to protect you, you were eliminated. he typically fired three tennis balls at a time which made for a decent impact spread and could maintain a pretty impressive rate of fire. Often he could get three volleys off before the initial balls hit s a barrage was pretty impressive.
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Post by aldenlulamoon on Jan 20, 2015 22:13:19 GMT -5
Thanks for the advice! I was reading a Vietnam soldier's memoir, and it talked a bit bout having pre-designated fire zones. I think that would be very easy to do at my field, since you can get a map of it easily, and it even has grid lines. Can anyone provide more specific details on how to make the sight? I'm not sure I understand it.
And Bat, what do you mean by 'aiming stakes?'
Thanks!
-Alden
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Post by brownien on Jan 21, 2015 21:39:15 GMT -5
Thought this could help you out a bit. www.hardscrabblefarm.com/ww2/60mm-demo.htmlI have been building a 60mm mortar of late. I am planning on using 40mm grenades to fire golfball sized foam projectiles roughly 75 yards. For a sight, I was just going to use a simple bubble level to get a base line, and measure the elevation off that in degrees. I can then associate the degrees of elevation to the range of the shot and dial in the first marking round to the correct distance. For the direction, once you get the mortar/howitzer set in the correct overall direction, use a peep sight parallel to the bubble level to traverse the gun on target (aiming stakes are used here when targets are obstructed by cover/trees/hills. The stakes are used to mark pre determined fire zones. To select one of the predetermined zones, traverse the peep sight onto the stake and dialing in the elevation.)
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Post by aldenlulamoon on Jan 21, 2015 23:12:48 GMT -5
Alright, thanks! now I just need to see what the best PSI for my gun is. I want to maintain around the same velocity for all my shots. I want to be able to fire it pretty far too, while still maintaining a semi-quick rate of fire. I'm thinking 40psi for my gun (once I do some more sealing, I'm confident I'll be able to get it that high)
I'm guessing the sight should be mounted to the CARRIAGE instead of the gun itself? it would be easy to make one, if I understood your info correctly. all I'd need is a small bubble level, some kind of scope or iron sights, and something with degrees of elevation marked on it? Then I'd align the barrel to the elevation on the sight (I could use a protractor or something couldn't I?) and depending on what distance, I'd adjust the elevation accordingly.
am I correct about this?
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2nd Bat
Master sergeant
Posts: 11,813
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Post by 2nd Bat on Jan 22, 2015 0:13:00 GMT -5
yes. Aiming stakes are typically white wooden rods that you pound into the ground and for our purposes would need to stand about four feet high. They are placed out a bit from your howitzer or mortar (six to 10 feet I would guess) and can have height markers notched into them. Your site is fixed on your weapon and moves with your elevation so looking through you can align perfectly with the stakes themselves and the height notch called for.
For PSI it ll depends on the size of your expansion chamber and the circumfrance of your tube and weight of what you are firing. A super tight fit, creating a perfect seal inside the tube is essential to good performance. In addition to foam rockets or tennis balls you can create flechette rounds by using foam discs sandwiching hundreds of old throw away BBs in between. (I also mix in a little TALC powder or ash). this creates an effective visual effect upon firing
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Post by aldenlulamoon on Jan 22, 2015 0:41:10 GMT -5
But I'm guessing that aiming stakes would not be very effective for a gun crew who wants to stay relatively mobile during the game?
I got a simple gun sight put together. It'll be attached to the same bolt that the gun elevation mount is. Now I just need to find a huge open field to test the range with XD I could go to the beach, but that'd be way too windy. Anyone have any ideas? (I live in the Salinas/Monterey area XD)
The sight consists of a circular piece with elevations marked on it that will be perpendicular to the ground and parallel with the gun barrel. This circular piece then has a block on the bottom with a 4 power rim-fire scope attached as well as a bubble level. it seems like it'll work, but did I do it right?
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2nd Bat
Master sergeant
Posts: 11,813
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Post by 2nd Bat on Jan 22, 2015 23:58:45 GMT -5
Company level 60 mm mortars seldom used aiming stakes as they were quite mobile. 81mm mortars and certainly 4.2 inch mortars typical used aiming stakes. When deployed part of the crew drill is the placing of the tube while other members are setting up the aiming stakes and still others are hauling and prepping ammunition.
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Post by aldenlulamoon on Jan 23, 2015 0:27:24 GMT -5
now I just need to print out a map and figure out a scale for it.
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