Variable Velocity Rifle

[far-trader]

Interesting idea but it sounds messy. There's the logistics of needing two seperate components to shoot, run out of one and you're left lugging useless deadweight. And then there's the small worry of a much larger more volatile explosive incendiary in the fuel tank, unless it's some explosafe variety like you say.

Anyway I've been pondering the last little while why there aren't any air compression type weapons. I saw some advanced design model a while back but can't recall the details now. Seemed like it would be a viable alternative for some uses, especially if your trooper is already equipped with a huge compressed air system in the form of an armored vac-suit. Care to tackle that design Corejob?

If "another clever solution to a nonexistent problem" appeals to you

 

[Todg]

Yet another clever solution to a nonexistent problem.

Reading 'Liquid Propellant Gun Technology' and recalling some designs of my own and ideas posted here and other Traveller forums, here is the variable velocity rifle (VVR).

The following represent one of a whole series of possible weapon utilizing liquid propellants.

The VVR is a small arm designed to fill the maximum number of roles and have extreme velocity. Delivered at TL 8, the VVR utilized stored liquid propellant to replace the chemical propellant of a conventional firearm. This has several benefits.

The VVR is a true caseless design. Because the liquid propellant is injected into the firing chamber as used, there is no need for case or primer. The propellant is stored in a tank located in the stock of the weapon, and a magazine containing the projectile only feeds that projectile into the breech.

Because of the need to atomize the propellant for ideal ignition, the liquid propellant is not injected into the firing chamber until immediately prior to firing. That gives this weapon a characteristic delay in firing (lock time) which, while not as extreme as a flintlock, is noticeable.

One of the advantages if this design is that it allows the user to control the amount of propellent injected for each round. Through the use of a simple variable valve, the shooter can adjust the amount of propellant injected, and hence the velocity of the.

The propellant is iniated by something very analagous to a sparkplug, and an internal battery is recharged via a system that captures some of the used to cycle the weapon.

Because liquid propellants typically have much more energy than conventional propellants, more rounds can be fired for the same volume of propellant.

The basic VVR uses regular gasoline for propellant, stored in a tank designed to minimize the risk of ignition or explosion (similar to the technology used in race car fuel tanks), however there is the remote possibility of ignition if the tank is struck by an incendiary or explosive projectile, or the VVR is exposed to prolonged high heat.

The buttstock fuel tank contains enough fuel to last through several 100 round magazines, depending on the power setting. The tank can be refilled through a simple filling port on the stock.

A small, 100 round drum magazine (containing bullets only) is inserted just forward of the grip. Some version are equipped with larger helical magazines that can hold 250 or more 'rounds'. The typical VVR is chambered for the standard 9mm bullet. At the low power setting , treat as SMG. At medium power, treat as ACR with 9MM slug ammunition, at high,, trat as a hoigh powered hunting rifle.

A 1 liter fuel tank contains enough fuel for about 2100 low powered (SMG equivalent) shots, or 1050 ACR equivalent shots or 700 high powered rifle shots.

Variations include models that use safer binary propellants that are nonflammable until mixed in the firing chamber, different calibers, magazine and fuel capacities. In addition, non-variable version using liquid propellant also exist.

The basic rifle described above masses 4kg, is 90cm in length and costs Cr600. VVRs are normally found with electronic sights because the variation in velocity effects the trajectory of the projectile. Electronic sights that compensate for velocity change are available at the standard cost.

 

[mike wightman]

Nice design, well done once again.

A couple of questions, if I may.

What do you think the upper rate of fire is going to be, and why 9mm calibre instead of ~5-6mm?

 

[Anthony]

Gasoline isn't a monopropellant -- it needs around 4x its own weight in oxygen (or nearly 20x its weight in air) to burn fully; using air would be very unhelpful. The most likely LP smallarms would be a binary mixture, probably something like H2O2/RP-1, and the major theoretical benefit is a greater ability to control burn rate and thus an ability to maintain peak chamber pressure longer.

 

[Todg]

Originally posted by Sigg Oddra:
Nice design, well done once again.

A couple of questions, if I may.

What do you think the upper rate of fire is going to be, and why 9mm calibre instead of ~5-6mm?

I picked a larger caliber because a small projectil at low velocity is going to be pretty useless.

 

[Todg]

Originally posted by Anthony:
Gasoline isn't a monopropellant -- it needs around 4x its own weight in oxygen (or nearly 20x its weight in air) to burn fully; using air would be very unhelpful.

Why? It works in both automobiles and in at least one experimental gasoline powered artillery piece built by the Army as a proof of concept.

K.I.S.S.

 

[Todg]

Originally posted by far-trader:
Interesting idea but it sounds messy. There's the logistics of needing two seperate components to shoot, run out of one and you're left lugging useless deadweight. And then there's the small worry of a much larger more volatile explosive incendiary in the fuel tank, unless it's some explosafe variety like you say.

The goal here isn't necessarily to design a better weapon, just one that is different. Not every culture is going to go down the same path.

As to the danger of gasoline, We drive cars aroudn every day full of the stuff, and contrary to TV, cars do not explode whenever they get into an accident. Use a racing type 'fuel cell' and they are very safe, unless something like an RPG hits your rifle, in which case you've got other problems. The most likely danger is going to be fire.

I'm also assuming your using gasoline (or something similar) to fuel your vehicles, so availability is not a problem.

As to the fact you have two components to your wea[pon, it's not any more complext that having powder and shot - something primitive armies dealt with.

Anyway I've been pondering the last little while why there aren't any air compression type weapons. I saw some advanced design model a while back but can't recall the details now. Seemed like it would be a viable alternative for some uses, especially if your trooper is already equipped with a huge compressed air system in the form of an armored vac-suit. Care to tackle that design Corejob?

Airguns have real limitations in terms of maximum velocity unless you use some kind of ram.

I actually own and shoot several larger caliber air rifles (large as in .50 caliber) made by Dennis Quackenbush. The typical air rifle has about the same performance as a black powder rifle.

I did have PC equipped with air rifles while on a planet with a semi-flammable atmosphere. I'll see what kind of high-tech version I can come up with.

 

[Anthony]

Originally posted by Corejob:
Why? It works in both automobiles and in at least one experimental gasoline powered artillery piece built by the Army as a proof of concept.[/QB]

Hm. Well, if you're willing to pump in 15-20 liters of air per gram of fuel, and you're willing to have a detonation velocity of only around 2100 meters per second, air works fine. I don't think that's practical for a rifle, and if your goal is a hyper-velocity cannon it's certainly not at all useful.

In the case of automobiles, they do in fact pump in that much air. I have no information about the artillery piece, presumably it does the same thing or else uses an air or oxygen tank.

 

[Todg]

Originally posted by Anthony:
Hm. Well, if you're willing to pump in 15-20 liters of air per gram of fuel, and you're willing to have a detonation velocity of only around 2100 meters per second, air works fine. I don't think that's practical for a rifle, and if your goal is a hyper-velocity cannon it's certainly not at all useful.

I thought the detonation velocity of gasoline was lower, more like 1700m/s. However, considering that propellants have a detonation velocity of less than 1,000m/s, gasoline seem just fine.

[NB: The cutoff for propellants and low explosives is generally a detonation velocity of aound 1000m/s. Detonation velocities above 1000m/s are considered high explosives.

 

[far-trader]

Originally posted by Corejob:
The goal here isn't necessarily to design a better weapon, just one that is different. Not every culture is going to go down the same path.

Yeah I got that and like the idea, one of the reasons I suggested the air rifle idea.

I'm also assuming your using gasoline (or something similar) to fuel your vehicles, so availability is not a problem.

D'oh, that was so obvious and I totally missed it. That makes it better in a lot of ways, especially if you expand on it and make some vehicle mounted guns. As for exploding cars yeah I groan everytime a car crash looms, though the movies and TV are getting a little better in that regard.

Airguns have real limitations in terms of maximum velocity unless you use some kind of ram.

I actually own and shoot several larger caliber air rifles (large as in .50 caliber) made by Dennis Quackenbush. The typical air rifle has about the same performance as a black powder rifle.

I did have PC equipped with air rifles while on a planet with a semi-flammable atmosphere. I'll see what kind of high-tech version I can come up with.

Nice air rifles, good to see them getting some serious treatment in the land of Daisy

So besides the noise reduction and flash elimination and semi-flammable (or explosive) atmospheres, and low tech or explosive poor cultures, do you see any other niches for air rifles? Feel free to save your answer for anything you come up with in the post (please and thank-you

) on a design. By the by, how do you make your designs? Are you using some game rule set or just a general experienced estimation? I know I've been quiet on your contributions, just sitting back and nodding a lot

so it's overdue but "Well done, and welcome aboard."

 

[Todg]

Originally posted by far-trader:
Nice air rifles, good to see them getting some serious treatment in the land of Daisy

Here's a link to Dennis' page.

http://www.connext.net/~daq/

Bigbore airguns have a long an illustrious history. They were used by the Austrian army during the Napoleonic wars (The Model 1799 designed by M. Girardoni and later bult by Contriner) and Lewis and Clark carried one on their Western journey. If you get a chance, look for "Gas, Air and Spring guns of the world" by WHB Smith.

So besides the noise reduction and flash elimination and semi-flammable (or explosive) atmospheres, and low tech or explosive poor cultures, do you see any other niches for air rifles?

For someone who is going to be cut off from supplies, like an explorer or survivalist, it is a great weapon. All you need to carry is material for bullets - any maleable metal, usually lead - although I did have a game where one of my players made ammo from gold to shoot from his airgun

I am most familiar with CT, so I tend to build weapons for that system. I do have both version of "Fire, Fusion and Steel" and have used that system to build guns too , although it doesn't work that well. Lastly there's "Guns, Guns, Guns."

Mostly, I rely on my own background. I'm a former federally licensed gun dealer, gun collector and firearms consultant. I've worked for a couple of well know gun manufacturers, as well as designing parts and silencers for Police Automatic Weapons Service. I am also a former Infantry officer and competition shooter - so I know firearms pretty well.

I'm currently working on my fist book - gun related of course.

If you are interested in a particular system, let me know and I'll take a look.

 

[Todg]

Originally posted by Anthony:
Gasoline isn't a monopropellant -- it needs around 4x its own weight in oxygen (or nearly 20x its weight in air) to burn fully; using air would be very unhelpful. The most likely LP smallarms would be a binary mixture, probably something like H2O2/RP-1, and the major theoretical benefit is a greater ability to control burn rate and thus an ability to maintain peak chamber pressure longer.

That's true of artillery, at least. But binary propellants have been almost completely abandoned in LP guns due to problems handling and mixing the oxidiers - lovely stuff like H2O2 and HNO3. Fuels have ranged from monomethyl hydrazine or unsymmetric dimethyl hydrazine to hydrocarbons such as decaline. Monopropellants are typically isopropylnitrate or Nitromethane, or some combination of miscible materials including the previous.

While control of burn rate (usually through regenerative systems) is a factor, there are several advantages of to LP guns. Storage of propellant can be maximized. Artillery zoning is easily accomplished. Reduced muzzle flash. And in general, LP guns have better performance than similar solid propellant guns.