SpudFiles

First off, I'd like to say my thanks to DR for inventing this system, even if it does seem kind of simple now.

<img src="http://www.spudfiles.com/forums/album_p ... &full=true&">

This is my fuel mix over water compression tank for use on my next project. As you can see, the hybrid is going to be kind of small. The chamber is 8" of SCH-80 1-1/4" seamless steel pipe.

The tank is made up of 12" of 2" SCH-40 PVC, with an endcap on the front and a threaded adapter and male plug on the back. The meter consists of a 1/4" x 6" SCH-40 steel pipe nipple which can fuel the tank up to a 2x/2 atm mix. I also added a small drain cock at the bottom to drain water after filling.

The water input is going to be from a modified bike pump with an input from a 2 liter camelback bladder work in a backpack. I don't want to use a garden hose, but if I have to, I've got a swivel female garden hose x 1/4" MNPT adapter I made.

I decided to fill the tank to 2 atmospheres for two reasons:
1.) I didn't want a huge 3" tank
2.) I need a way to mix the fuel mixture. A fan would get water in it, so I figured the injected air compressing it to a 2x/2 atm mix would mix the mixture good enough.

As you can also see, I don't have a Schrader added yet for air injection. I'm going to wait till I order all the steel from McMaster and get a threaded one from there.

Tell me what you think!

Geez, could you direct me too dr's hybrid so I can see his?
And how does this work?
I'm dumb.
I want to do a hybrid sometime but I don't understand the fueling method.

frankrede wrote:Geez, could you direct me too dr's hybrid so I can see his?
And how does this work?
I'm dumb.
I want to do a hybrid sometime but I don't understand the fueling method.

isn't the idea behind a hybrid just if you put 3x the fuel you put 3x the atmospere?

FrankRede, <a href="http://pages.villagephotos.com/page.asp ... 3731">DR's Gen II</a>.

PyroManic, not exactly. Now that hybrids always maintain a relatively constant fuel - air ratio, that simply leaves that once the 1x 'mix' is exceeded that the discussed mixture is 'hybrid'. The limits of the mixes are not bound to whole integers, rather they are commonly refered to as whole integers for the sake of generally lacking standards of accurate measurement. Techincally you could have a 2.54367x mix. Hopefully that made sense, and helped out.

EDIT-
The SpudFiles Wiki should be updated to define the differences, and operations of the '1st' and '2nd' 'Generation' dubbed hybrids. Ill work on it myself, but quite frankly im quite hard to understand when it comes to me trying to describe something techincal. Thank the god of your parents choice I dont write owner manuals...

Thats not propane, What is it?

Lets see what other common flammable gas comes in disposable yellow cylinders... MAPP?

MAPP isnt as common over here,i've only seen it in plumbing stores in back shelves etc.I could see how he wouldn't no what it was.

markfh11q wrote:This is my fuel mix over water compression tank for use on my next project...

How does water come into play? Using water to pressurize the fuel/air mix?

Exactly. There are three Gen II'S in existance. One is this one, I made one, and DR from Spud Tech made one.

SpudStuff wrote:Exactly. There are three Gen II'S in existance. One is this one, I made one, and DR from Spud Tech made one.

This is intriguing. What is the theory and actual resultant performance increase? The molar weight of fuel / air is the same as unpressurized. You'd sum the pressure from combustion with the prior-to-ignition pressure. It would seem that the overall volume of gas to propel the spud is the same either way, but with a much higher moment-of-ignition pressure. I would predict you'd be able to use a shorter barrel to get the same result of a longer barrel?

The only increase in performance would be from a more optimum ratio of fuel to air.

With a traditional hybrid, you have to add too much fuel and then inject air. If you inject even a pound or so off, you may not get a good enough mix.

With this, all you're doing is taking a 1x/1 atm mix and compressing it into your ignition chamber using water from a hose. This eliminates user error in injecting air and also makes it MUCH simpler and more fun to use. You can go up as high as your water pressure will let you, (mine hovers right around 90).

markfh11q wrote:The only increase in performance would be from a more optimum ratio of fuel to air.

With a traditional hybrid, you have to add too much fuel and then inject air. If you inject even a pound or so off, you may not get a good enough mix.

With this, all you're doing is taking a 1x/1 atm mix and compressing it into your ignition chamber using water from a hose. This eliminates user error in injecting air and also makes it MUCH simpler and more fun to use. You can go up as high as your water pressure will let you, (mine hovers right around 90).

why do you get a performance increase then?

You can achieve higher mixes much easier. With a normal hybrid you need to worry about the pressure in the chamber. With this you just open the valve, pressurise, close the valve and shoot stuff.