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insane springer air rifle

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insane springer air rifle

Unread postAuthor: 95gtzspec2 » Thu Oct 29, 2009 2:39 am

i got to thinking the other day while i was shooting my POS 495 fps crossman pellet gun on how i can make it better
what if a person was to make up a air rifle consisting of
valve springs with a 79lb rating (seat load) on em from a cavalier use about ohhhh 10 or 12
a 1 1/2" aluminum machined drive piston fused with window weld as the seal
8" - 12" for a drive chamber
.22 for the ammo

full galvonized body with a break barrel design and useing an after market or factory barrel

i figured out that the cocking load would be around 120lbs
and around 300 - 400lbs + driveing force

i have a 2 part trigger worked out and the body designs but what im woundering is does anybody know what fps this thing would be pushing

i know that some people completely hate these guns and will say just make one that runs on air or a cannon but i like that its a springer and you dont have to carry compressors or get co2 refilled

and the spring is loaded with a screw on cap in the back of the rifle so theres no need for springs compressors or broken fingers

i welcome all positive and negative feedback :idea:
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Re: insane springer air rifle

Unread postAuthor: jackssmirkingrevenge » Thu Oct 29, 2009 3:11 am

95gtzspec2 wrote:I know that some people completely hate these guns and will say just make one that runs on air or a cannon but i like that its a springer and you dont have to carry compressors or get co2 refilled


It's not about "hate", I have a beautifulWeihrauch HW97 which I love to bits, and if I had the cash to spare I would certainly order a Whiscombe for my collection.

The things is that for most amateur builders, a powerful springer requires a certain level of technical capability as well as material and tooling beyond their capability. There's a good discussion on the issues here.

If you have the resources though, go for it :D
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Unread postAuthor: lozz08 » Thu Oct 29, 2009 8:22 am

I'm making one, but its powered by air and is .177" caliber. As in its not actually powered by air but pressurised air acts as a spring behind the piston.
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Unread postAuthor: D_Hall » Thu Oct 29, 2009 8:37 am

After a bit you're going to reach the ol' point of diminishing returns. In other words, I suspect a spring half the size of the one you're proposing would be indistinguishable from yours if all you looked at was the speed of the pellet coming out the muzzle.
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Unread postAuthor: 95gtzspec2 » Thu Oct 29, 2009 6:00 pm

muzzle velocity is important gamo has one out rated at 1600 fps (accuracy drops after 500 shots) for a good chunk of change and i live in canada and i aint spending that much money for that good of a gun. i talked to a guy who apparently claims itl shoot through a 2x4 @ 20m on pba raptors
but a spring half the size wouldnt be adequate engouh stiffer spring would give more projectile mase but bigger and longer would double to tripple the projectile mass and the plunger will only create as much air chamber cfm and the spring will push
guns rated @ 1000fps have twice thrust force of one @ 500fps and the coils are gnerally are thicker
a spring with 150lb thrust load behind it has around 40 - 50lb cocking effect on a lever gun and will produce around 1300 fps on good seals and oil w/t 5" piston chamber
building a springer is alot like machining and building short blocks of engines same principals it cant be done without reaserch and development
and spud guns are to simple of a design rip out the cat on your car and put a spark plug in your o2 sensor and your got a flame thrower exhaust
and projectiles will shoot out of the tail pipe same princpals apply to spud guns
co2 and air guns, a check valve and air compressor u got a gun
but to house the raw power of a piece of metal sitting on a 400lb + thrust seat load is complex and makeing a piston stop that wont blow out of the gun when its hits & with out bending the drive rods
and i like to compare guns to engines - everytime i build a short block i build it for natural compression not forced induction


but i wanna construct a springer capable of the 2000fps + range and hope the recoil of the srping wont take my head off

when its done ill post info on it
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Unread postAuthor: Technician1002 » Thu Oct 29, 2009 7:38 pm

lozz08 wrote:I'm making one, but its powered by air and is .177" caliber. As in its not actually powered by air but pressurised air acts as a spring behind the piston.


I'm going larger. I'm looking at a 3 inch piston driven by my current 2.5 inch build driving a golf ball. Modeling shows possible supersonic launches at 200 PSI in the 2.5 inch air cannon. Peak pressure in the GB barrel is likely to exceed 800 PSI on launch.
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Unread postAuthor: boyntonstu » Thu Oct 29, 2009 7:41 pm

Technician1002 wrote:
lozz08 wrote:I'm making one, but its powered by air and is .177" caliber. As in its not actually powered by air but pressurised air acts as a spring behind the piston.


I'm going larger. I'm looking at a 3 inch piston driven by my current 2.5 inch build driving a golf ball. Modeling shows possible supersonic launches at 200 PSI in the 2.5 inch air cannon. Peak pressure in the GB barrel is likely to exceed 800 PSI on launch.


???? How do you start with 200 psi in the chamber an end up with 800 psi on the gb?
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Unread postAuthor: D_Hall » Thu Oct 29, 2009 8:24 pm

boyntonstu wrote:???? How do you start with 200 psi in the chamber an end up with 800 psi on the gb?

Google for "2 stage light gas gun." That's not exactly what Tech's doing, but it will answer the question you've just asked.
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Unread postAuthor: Technician1002 » Thu Oct 29, 2009 11:30 pm

boyntonstu wrote:???? How do you start with 200 psi in the chamber an end up with 800 psi on the gb?


This works on the same principal that causes spuds to have enough pressure to punch holes in 3/4 inch plywood.

It has a long acceleration zone where speed is picked up with the accompanying kinetic energy. Then in a relatively short deceleration zone the the forces is very high often causing peak pressures high enough to punch holes in 3/4 inch plywood. This short deceleration zone is replicated in air.

A piston is driven by air for several feet at say an average of 100PSI. 1/2 way to the far end, the pressure goes from one atm to 2 or about 15PSI. At half way the piston is still accelerating. At 3/4 the way to the end, the pressure is at 4 atm in front, still under the driving pressure behind, so the piston is still accelerating. Near the end of travel the pressure sharply builds very high. The charge of compressed air enters the barrel at high pressure, then expands, often at supersonic speeds. This example does not cover heating from compression. The heat of compression heats the gas to become a light gas. Due to the relatively low pressure at the beginning of the compression stroke of the piston, the GB moves very little in the GB barrel.

I have been trying to work the dynamics on what size and mass piston to use to drive the golfball, but it's pretty advanced for me. I have the basic theory but not the engineering math. I may start with a light foam piston and use pick up coils to find the stopping distance and work the weight up in stages to where the piston stops just short of the end of the cylinder and provides maximum energy transfer. It may be a trial and error engineering project.

I won't build this right away due to the holidays and winter. It may become a spring project. It'l be an air cannon powered golfball springer.
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Unread postAuthor: Ragnarok » Fri Oct 30, 2009 6:18 am

95gtzspec2 wrote:guns rated @ 1000fps have twice thrust force of one @ 500fps

No, it doesn't. It has four times the force, because 1000 fps is four times the energy of 500 fps.

but i wanna construct a springer capable of the 2000fps + range and hope the recoil of the srping wont take my head off

Um... not all that smart an idea.

The 1600 fps "rated" Gamo doesn't even actually manage 1600 fps - they seldom do manage what they say they will. Yet, it is still enough that even grown men have to cock it with both hands. (That said, I do have a design for a cocking system that would reduce the effort needed.)

Trying to build a 2000 fps springer would rip it and you apart unless it was built like a tank.

If it's even possible, I'm talking top of the line materials, expensive machining, computer modelling, getting people who really know their stuff poring over your designs trying to find any weakness or mistake.

I wouldn't even consider making something like that with any less care and expense.
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Unread postAuthor: Marco321 » Fri Oct 30, 2009 7:47 am

To get 2000fps+ you would need like solid propellant, but we dont speak of that here.

To hit 2000fps+ you would need the chuck norris of springs. But to contain the spring you would need nothing short of thick, strong steel, burly arms and a will of steel, as well as Gary Barnes workshop.

In short, making a 1000fps springer would be incredibly hard and dangerous, let alone 2000*fps springer.

As ragnarok said, you would need a good workshop with computer software, as well as a team of engineers and scientists specializing in various fields.
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Unread postAuthor: jackssmirkingrevenge » Fri Oct 30, 2009 8:38 am

Marco321 wrote:To hit 2000fps+ you would need the chuck norris of springs. But to contain the spring you would need nothing short of thick, strong steel, burly arms and a will of steel, as well as Gary Barnes workshop.


I think that mechanical springs aren't worth the trouble if you're going large, I would go with what Tech is doing and use air pressure to accelerate the piston, much easier than trying to cock a massive coil spring.

Another idea would be to take this design and scale it up, using a leaf spring from a car suspension :D
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Unread postAuthor: Marco321 » Fri Oct 30, 2009 8:50 am

jackssmirkingrevenge wrote:
Marco321 wrote:To hit 2000fps+ you would need the chuck norris of springs. But to contain the spring you would need nothing short of thick, strong steel, burly arms and a will of steel, as well as Gary Barnes workshop.


I think that mechanical springs aren't worth the trouble if you're going large, I would go with what Tech is doing and use air pressure to accelerate the piston, much easier than trying to cock a massive coil spring.

Another idea would be to take this design and scale it up, using a leaf spring from a car suspension :D


Oh yeah certainly, that was sort of my point lol. Cant beat air pressure :D
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Unread postAuthor: Ragnarok » Fri Oct 30, 2009 10:03 am

Marco321 wrote:To get 2000fps+ you would need like solid propellant...

...or a hybrid. There are two I can think of that have recorded 2000 fps+ velocities.

Possibly one or two others as well.

I would also note that one of the fastest projectiles I know of at 110,000 fps (not a typo) didn't use a combustible propellant.

Similarly, at a more leisurely 8,000 fps, the US Navy railgun doesn't use solid propellant.
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Unread postAuthor: Technician1002 » Fri Oct 30, 2009 10:13 am

Ragnarok wrote:
95gtzspec2 wrote:guns rated @ 1000fps have twice thrust force of one @ 500fps

No, it doesn't. It has four times the force, because 1000 fps is four times the energy of 500 fps.

but i wanna construct a springer capable of the 2000fps + range and hope the recoil of the srping wont take my head off

Um... not all that smart an idea.

The 1600 fps "rated" Gamo doesn't even actually manage 1600 fps - they seldom do manage what they say they will. Yet, it is still enough that even grown men have to cock it with both hands. (That said, I do have a design for a cocking system that would reduce the effort needed.)

Trying to build a 2000 fps springer would rip it and you apart unless it was built like a tank.

If it's even possible, I'm talking top of the line materials, expensive machining, computer modelling, getting people who really know their stuff poring over your designs trying to find any weakness or mistake.

I wouldn't even consider making something like that with any less care and expense.


As a physics nut and general science junkie lets get on the same page for the terms used.

Force is pressure.
Energy is power. With that in mind, the formula for changing the speed of a mass is Force = Mass times Acceleration.

Accelerating from 0-50MPH requires the same force as accelerating from 50-100MPH. The force to slow down is the same, but in the opposite direction. Now on to ENERGY.

The amount of energy to push something that is going 50 mile per hour to 100 miles per hour is much greater than the energy required to push something from 0 mph to 50 mph. Because work is force times distance, the distance traveled by the car starting at rest is much less than the distance traveled by the car starting at 50 MPH. Much more work is required to apply the force for the same time over the longer distance.

Think foot pounds. In the first case with the force being equal in both accelerations, the pounds of force is the same. The feet traveled is vastly different in the same time frame to accelerate an additional 50 MPH. The car going 100 MPH has 4X the kinetic energy of the one going 50 MPH. The force if an even force only took twice as long to apply, but the energy required to apply the force went up as the speed went up.

With limited HP in engines, most cars apply higher force to accelerate at lower speeds by using a lower gear ratio. Acceleration drops off at freeway speeds because the engine power does not increase each time you shift up a gear to keep the accelerating force up. It drops off.
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