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Greenmtnphantom 01-12-2011 05:07 PM

Nelson Valve Evolution (Project Leprechaun)
 
This started in several of our heads and has spilled out into a few threads.

It's no secret that I am a fan of the Nelson design. Lots of small companies came up with lots of different variations of it. Some of the ideas, I'm sure were good and for one reason or another the company or the gun just didn't survive.

Pump is growing again and so is Stock Class. High end Nelson guns are a reality right now. Now is the time to dig up good ideas both old and new.

Companies like RTR and the "Redux factory" are bringing innovative new high quality nelson based guns to market.

Companies like ASP and Lapco are selling quality oldschool parts like various sized power tubes, open faced TPC's and lightened hammers.

The big boys Tippmann and Kee are even throwing there hats into the ring by bringing back old Nelson based guns.

No one is doing much if anything to improve the inside of the gun.

We have enough people that are smart and talented enough to figure this out. I was planning on working quietly on this until I got some place. There is so much information, so many old ideas that might have worked, so many new ideas that might work.

Lets get them out there.

We can make Nelsons work better I know it. I call this project "Leperchaun"

A few thoughts I had are:

It's been said that increasing flow makes efficiency better.

I think that redesigning the cup seal and valve is beveled so that the cup seals at an angle inside the valve nut will increase flow and efficiency.

Lightening the hammer seems to be an improvement. I think the LAPCO design can be improved on by relacing the friction points along the outside with Delrin. The reason I think this is better is that it would cut down on friction, allowing for a lightermain spring to be used to have the same weight hammer provide the same dwell as a heaveir hammer would have. This means a lighter pump stroke.

I'd like to see a bigger power tube in the Phantom/Garg/Duck length.

Open faced "TPC" I think this is a must.

Low pressure has been talked about and some are working on it in secret, Lets talk about that.

I've mentioned before that I think Nelsons set up right could be extreemely efficient on Liquid. Lets talk about that. I've got a power tube that I think might work very well for this purpose and will be testing it now that I have a siphon tank. I think once I get a good siphon system put together it could be used in Drop outs to run liquid out of a 12ie! You are tipping the gun forward so the liquid should be able to be sucked out of the horizontal 12ie if the gun is tuned properly.

MaD 01-12-2011 05:26 PM

I was recently thinking the same thing about a cup seal. It seems to me that if it was shaped like a football (maybe with a similar valve face) that you might get better flow through it. Also, AKA came up with a pretty unique design with the flower shape (for lack of a better term) that might have some potential. They might have a patent on it though.

I think you might get mixed input on this though. I find that folks who have figured things out or have some financial stake in products tend to keep their own findings to themselves.

Greenmtnphantom 01-12-2011 05:27 PM

Looking forward to hearing about it. What ideas do you have cj? What do you think of the ideas above? I know this has been a project of your's as well.

MaD any pictures or more information on the AKA one? Was it for their cockers?

REDNA 01-12-2011 05:41 PM

me as well

MaD 01-12-2011 05:42 PM

AKA made low pressure / high flow valves for Spyders and Cockers. Kmac has some pictures:
Autococker Valves & Valve Kits Photo Gallery by Kenneth MacDowell at pbase.com

The main design changes were the larger valve face and the flower shaped cup seal. Bob long made a similar valve at one point with a brass cup seal almost the same shape and a ramped output. There aren't that many of those out there so I suspect there may have been some sort of patent issue.

So one thing to think about is the size of the valve face. Not sure what would be optimal but it's been pretty well proven that a larger valve face allows for lower pressure. Actually, a large valve face may require lower pressure as the high pressure gas pushes the valve closed more quickly.

I realize most of this relates to sheridan / cocker valve setups and gas flowing through a powertube is a bit different than out the side of the valve but I think that some of the designs might have some application here.

Have Blue 01-12-2011 05:44 PM

Quote:

Originally Posted by Greenmtnphantom (Post 1636224)
Looking forward to hearing about it. What ideas do you have cj? What do you think of the ideas above? I know this has been a project of your's as well.

MaD any pictures or more information on the AKA one? Was it for their cockers?

Ah, the old Tornado valve for the cocker. The cupseal essentially had a wide flange around it. The idea was that the air flowing from further back in the chamber would help the cupseal slam shut very quickly. The opposite approach was taken by the Maddmann Rocket valves - make the cupseal conical to impede the air as little as possible, and get the valve spring out of the chamber entirely.

You might be able to do a Nelson analogue to the Maddmann by sticking a wave spring between the retainer and the powertube flange - by moving the valve spring out of the valve chamber, you could go insane with volume reduction.

Greenmtnphantom 01-12-2011 05:45 PM

Taken from another thread that I am talking about the same thing:
Quote:

Originally Posted by Have Blue (Post 1636242)
The cupseal was going to be the next part of the valvetrain I was going to look at - I machined slots in a CCI cupseal a while back in an attempt to improve flow around the cup edge, and I think I sent it off to someone to test. Either that, or it may actually be in my own Phantom yet and I've forgotten about it.

I did experiment with volume reducers in the valve chamber long ago, but they wound up impeding flow rather than reducing wasted space. I've got ideas on fixing that, but like everything else, I just need time.

One thing that I'm curious about is using the old style long CCI powertubes with the open faced TPC - will the extra length (and minimally reduced volume) improve efficiency, or is the slight expansion through the TPC beneficial? Perhaps the lower reciprocating mass of the newer, shorter powertube helps improve efficiency? Could the Trracer stub 'valve stem' and hammer with integrated powertube be the ultimate in Nelson valvetrains?

I'm going to quote that and post it in the thread I jsut started but I'll answer it here to. Double check with him but I believe Splattttttt found that the longer power tubes provide better efficiency. I've heard though that Trraccers were very efficient.

The devolumizers that RTR developed work really well. at one point I compaired mty Phantom to my Gargoyle with the exact same setups the only difference being the valve insert. If we are going to lower the operating pressure though devolumizing might not be what we want to do.

I think simply cutting the brass cup down so that the lip around the outside was level with the seal would be a cheap minor improvement but not the end solution

Greenmtnphantom 01-12-2011 05:54 PM

Quote:

Originally Posted by MaD (Post 1636254)
So one thing to think about is the size of the valve face. Not sure what would be optimal but it's been pretty well proven that a larger valve face allows for lower pressure. Actually, a large valve face may require lower pressure as the high pressure gas pushes the valve closed more quickly.

I realize most of this relates to sheridan / cocker valve setups and gas flowing through a powertube is a bit different than out the side of the valve but I think that some of the designs might have some application here.

Jack has gone down to I think 350 or 400psi operating pressure with current designs.

I think using a cocker valve spring, a hard one, that between the preload because the spring is longer and the harder spring we are going to be able to run low pressure without having to increase the face of the cup seal at all.

MaD 01-12-2011 06:08 PM

I know Jack and others have done quite a bit of testing with various setups including regulated. I don't know the results offhand but I think folks have found some benefit in efficiency from running regulated setups in both the sheridan and nelson world.

I think the first question I have is, when you're going after the ultimate nelson valve design, what are you looking for? Some folks seem to want to stretch a 12g as far as it will go (40-50) while throwing some consistency out the window. They might be willing to have some FPS fluctuations or drop off at the end in order to get more balls out of the barrel. My goal would be a reasonable amount (30-40) of perfectly consistent shots in the 280 fps range.

desertT1 01-12-2011 06:16 PM

Metadyne has a reg built into their thumb pump don't they? I think something like that would help stretch the 12g as well as adding consistency. That might be something to look into.


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