Hey Carl, paintball copies airsoft

[Mysteryfish]

... pffff.

[MadMax]

I didn't notice the manual link before:

http://www.tippmann.com/pdfs/products/C3/c3manual.pdf

This is a combustion gun. There's an ignition module and a mix adjuster (fps adjustment). Very cool. Too bad it needs a large combustion chamber. I think this is because the marker is designed to start with the chamber at atmospheric pressure. I was hoping to go with a smaller chamber that would start at 2-3 atm.

[Mysteryfish]

Sweet.

Doubters/speculators: SUCKIT!




Madmax, I don't know enough to know the relevance of what you're saying, but is it a "dooming" kind of statement? Or does it look more like just a puzzle piece type of dilemma?

(i'm referring to transfering the technology to other applications, ie airsoft etc...)

**the manual's neat**

Would something like a piezo work for ignition?

Or does a piezo-electric igniter have a limited lifetime?

[Fulcrum77]

Originally Posted by MadMax

Where did you read about the combustion system? I'd love to get more details on this marker. It would certainly explain how they surmounted the combustion issues. I couldn't beat my problem with a reasonably sized chamber. I had to go with bigass can about the same size in the PEP if I were to keep things at a starting pressure of 1atm. I can see how they could promise consistent performance with temperature if they went with combustion.

bcpaintball.com forums had a discussion there, and not all of them are speedball types there.

And also, you already found it MadMax, from examining the blown out diagram from the manual. They kinda gloss over the use of combustion in it too. It's not really a point they emphasize.

From my feel of the issue, it really does open up an opportunity for people who can't get co2/air fills (read: stuck outside of major metro areas in the US) or play in cold weather, where CO2 paintballing faces the same issues as GBB performance.

Also I'm wary of how "warm" the receiver would get rapidfiring the thing. I'm sure the first thing someone's going to try to do is to mod it to fire semi-auto.

[MadMax]

In order to propel a pellet to appreciable velocity, you tend to need around 100psi sustained for most of the barrel length (assuming a reasonable length around 375mm).

When you combust a butane-air mixture in a closed vessel starting at atmospheric pressure, you can acheive a pressure around 100psi, but that pressure will decay as the pellet travels down the barrel . As the pellet takes it's trip down the barrel, the gas space volume between the pellet and the combustion chamber increases. Some leakage around the pellet also contributes to some pressure decay.

With a very large combustion chamber like the Tippmann PEP, you've got a lot of initial volume starting at 100psi so the pressure doesn't decay very much as the ball flies down the barrel.

However, I was hoping to fit my combustion chamber in the slim profile of an 870 type shotty. Because of this, I couldn't fit the chamber that I needed. Furthermore, said chamber would have to be elongated and on the narrow side. This is not conducive to very rapid and complete combustion. You get the fastest flame propagation in short squat chambers (closer to spherical shapes is better if the spark plug is at the centre).

Conversely I was working with long tubular chambers of comparatively small radius wrt to length.

I tried to beat this problem with a high pressure setup. I was basing my designs around a pump action shotty so I figured that a bit of elbow grease could precompress the air-butane mix to say 2-3atm (30-45psig). Precompression would greatly increase the peak pressure (linearly related to atmospheric pressure ~15psi) and I hoped that it could reduce some of the chamber shape problems. Higher compression ratios crunch molecules together and greatly speed flame propagation.

The problem which finally stymied me was designing a seal which could be airtight yet survive combustion temperatures. Butane flame fronts can reach 1900C which is well beyond what organic elastomers can durably take.

I think the PEP operates with the mix initially at atmospheric pressure. Because of this, you wouldn't have problems with the fuel mix leaking past the ball very much. You could use the ball as the forward plug to prevent gas from oozing out the barrel.

At one point, I thought about mixing in a bit of sacrificial liquid like water into the butane reservoir. The idea was to spurt a little liquid onto the oring which would evaporate and absorb heat so the oring didn't actually get singed. You can observe a similar effect by soaking a piece of paper in ethanol. Light it on fire and the paper doesn't burn until all of the ethanol evaporates. Evaporating parrafin prevents the wick on a candle from burning as fast as a cotton string with no wax would burn.

My test combustion chamber could be prepressurized, but the movable seal on it wasn't durable. Liquid oring preservation didn't show to be reliable. It wasn't possible to get a consistent wetting of the oring. Silicone oil would have left a more lasting film, but I was concerned with the combustion products of silicone oil. I didn't really want to invent the first airsoft gun finally deserving the designation of "Cancer gun".

The reason I was looking at butane instead of propane, was that a smaller volume of butane was necessary to hit the ideal mix fraction with air. It allowed slightly more air (20% oxygen) in the combustion chamber and consequently more energy. More carbon dioxide produced = more energy req' more oxygen.

With the exception of gas mortars and odd funny guns, I couldn't shoehorn a combustion system into an airsoft gun. I did work out a pretty cool ignition arrangement for a shell loaded nerf mortar though.

Unfortunately liability reasons have convinced me to shy away from productizing a mortar launcher and product development of a mortar within a 750sq ft apartment is rather annoying.

[MadMax]

The warm up issue probably isn't all that much of a big deal. Most of the hot gases (about 87%) get blown out the barrel. The remaining 13% get pumped out when the gun is cycled. Hot gaseous combustion products don't have all that much heat capacity (not much heat energy per gram) because they're not very dense (remember your ideal gas laws?) and their heat transfer to the combustion chamber is through convection which isn't that fast at transfering heat.

The situation isn't like an engine cylinder which blasts away at a few dozen ignitions per second and has a high precompression factor.

I think I'll order a PEP just for MadMaxing fun. Maybe I could rejigger it into being an autococking electropneumatic Striker/CrowdSweeper shotty. Those things have a nice big carousel to stuff a combustion chamber into.

[Fulcrum77]

So it does look like it uses exhast gas to fire, I had assumed with the second piston, that the exhast didn't hit the paintball at all.

What do you think liablity issues lay with it, would a combustion powered bb launcher be allowed at most fields, or would it be covered under a pyrotechnics ban if the field had any such ban?

[Mysteryfish]

Thanks Madmax,

Very very informative.

I'm not all the way there for a large part of it, but I understand why "too bad it's so big" now sortof.

[CDN_Stalker]

Originally Posted by Greylocks

Why do folks always call propane 'ProPAIN'???

Does it hurt you more or something?

Short answer................. yes!

[Avenging Angel]

Okay, so I was wrong... heh. But, it's still pump action. I'm wondering if you could even attempt to make something that's fully automatic with a propane propellant. You'd think that the chamber would overheat and start to warp...

[made Man]

It uses exhaust gases to propel the paintball? Hmmmm would it be a lot cooler to use the expanding gases as a spring in AEG that moves a piston which pushes the air out, and then use the exhaust gases for the blow back effect?

[Skruface]

Update:

http://www.tippmann.com/about_us/pre...ils.aspx?id=16

"Tippmann Enters Airsoft Category with Heavyweight Products

2/9/2006

BUFFALO GROVE, IL - FEBRUARY 9, 2006 - Tippmann Sports, the leading manufacturer of high-performance paintball products, has entered a new and increasingly popular category with the company's first-ever line of Airsoft guns and accessories through a strategic alliance with Palco Sports. Tippmann's initial, well-rounded Airsoft offering includes a complete line of Tippmann branded, spring-operated pistols and rifles, CO2 and "green gas" powered pistols and automatic electric rifles (AEG Technology). The company is also introducing a number of high-quality accessories, including a target, replacement magazine and a new line of BBs, which will be marketed under the Straight Shot™ name.

"Entering the Airsoft category was a natural extension for us," said Patrick Ehren, Vice President of Sales and Marketing for Tippmann Sports. "Palco's 10 years of experience in the Airsoft category and their desire to partner with Tippmann to accelerate new product development in the category made the relationship a logical alliance. The Tippmann name has been synonymous with quality craftsmanship and performance since we started in paintball 20 years ago. Now, we're excited to leverage our industry-leading paintball experience by introducing a line of products to the growing number of Airsoft players around the country."

Tippmann's new Airsoft guns are expected to appeal to players of all skill levels, but especially existing players seeking a durable upgrade with enhanced features. All of the company's premium, heavyweight pistols and rifles are easy to operate, true to scale, feature a high rate of fire and utilize the Flatline Hop-Up System for longer, straighter shots.

"We think Airsoft players will be impressed by the combination of durability, feel and value they find in Tippmann products," Ehren added. "Plus, we're hopeful that we'll be able to help elevate the category by building awareness and generating excitement for Airsoft at the grassroots level. Long term, we'd like to bring experienced players together more often while providing newer players additional opportunities to discover this great game."

Airsoft products from Tippmann Sports will be available at paintball specialty and sporting goods outlets beginning in April 2006. The company's new line of guns will carry a variety of price points ranging from $24.95 for a spring-powered pistol to $149.95 for a full-size AEG rifle. For additional details, please call Tippmann Sports at 1-800-533-4831. The company's Airsoft line will also be included on the Tippmann Website, www.tippmann.com, when the products begin shipping in early April.

Celebrating its 20th anniversary in 2006, Tippmann Sports prides itself on quality manufacturing and the pursuit of cutting edge technology and design. The company serves the growing paintball and Airsoft industries from its corporate headquarters in Fort Wayne, IN. Tippmann Sports' complete line of paintball markers and accessories can be found at paintball stores and fields as well as mass retail and sporting goods outlets throughout the world. "

[Deftonius]

Originally Posted by made Man

BHUAHAHAHA! He's wearing RealTree

It's actually a Renegade jersey, comes in many patterns, designed for paintball.

[Lisa]

more manufactures can't be bad. and the guns can't be worse then hudson.

[GraveTech]

I would normally agree that more manufacturers isn't bad, but this is Tippmann. This is going to bring the sport to more ignorant people and young children then it has before. On the other hand we may (seriously doubt it though) see a serious move of products into Canada which would only be a good thing. In the end I think it is a mixed blessing.