Fuels

[Mark]

I was wondering if anyone had run a pulsejet on pure acetone? I was thinking about trying it just to add it to our repertoire of fuels and their characteristics, just for the heck of it. Maybe I could dissolve some acetylene in it too, ha, just kidding, but it did cross my mind as acetone is what acetylene is dissolved in under pressure in an acetylene tank.
With the price of gasoline going up, it looks like methanol is about to become cheaper than gasoline.
Then too I once made a thick solution of nitrocellulose dissolved in acetone, I wonder how that would burn? Expensively for sure, I used some rifle smokeless power as a source of nitrocellulose. I wonder if I could even get pure nitromethane to run in a pulsejet? I've got about 3 quarts left, I might as well use it up in some fun way.
I'm not expecting any great results with the acetone, all fuels do about the same overall if mixed with their proper ratio of air. It would make for a cool fuel though, it evaporates very quickly, maybe of benefit in the throat of an engine to make the air denser. Imagine ice on the head of the jet and being red hot in the combustion chamber. My 3 inch diameter pipe pulsejet head bell gets almost ice cold even with the engine running for a few minutes.
Here's my humble 3 inch diameter pulsejet fuel intake, dressed up with Larry's fine lines and details. It makes a foggy mist of methanol that really keeps the head very cold.
Mark

[Mark]

This is the 3 inch diameter pulsejet. It will sometimes start on the very first pop either by piezo clicker or also by waving a lighter under the tail end after a prime or squirt of methanol from a spray bottle. El primitive but it works.
Mark

[Mike Everman]

Cool Mark. I like the tiger stripes on the Logan exhaust. High harmonic resonance mode?

[Mark]

Cool Mark. I like the tiger stripes on the Logan exhaust. High harmonic resonance mode?

Decorative buffing, hit a spot, skip a spot on my grinder with one side a wire wheel. I don't know why I did that, just wanted to when I started to clean it up one day.
I did a 2.25 inch stainless steel pipe about 4 feet long that way too, and it really came out nice. The hues show up more or less depending on how the light strikes it, it definitely looks tiger stripe exotic, its banding pattern is wavy as well . Try it sometime, a tiger buff motif.
Mark

[Mark]

Today I attempted to run my Dynajet on MAPP gas and propane via the intake. Neither worked. Then I tried nitromethane. That wouldn't even pop, pure nitro will barely even burn if you light it with a match. But to start off my day of frustration, I tried pure acetone, I got some nice pops and brief revs but it would never catch and run constantly. I wonder what the window of opportunity is for acetone, the ratio of fuel to air? I guess I could look it up, under fussy fuels.
So then I scaled down, trying propane with my Tigerjet again via the intake. I became frustrated and opted for some methanol just to confirm for myself that the jet would run.
Had I preheated or injected the fuel into the combustion chamber, the results probably would have been different.
And the whole while I kept worrying about a possible ball of fire from fooling around with pressurized fuel in my garage. Best to be toying in the open air. It is also annoying when the propane becomes cold and doesn't want to evaporate fast enough. I tried a small tank and then a 20 pound tank. I finally got tired of breathing acetone, MAPP gas, propane, nitromethane, and methanol which was the only fuel that wanted to work for me today. I suppose I could have inhaled some gasoline to round out my day but I didn't.
Mark

[dwenger]

Mark,

I am having the same problem with propane via the intake. Any idea why propane and other fuels are hard to run on when not injected??

I wondered if you could give me some pointers on direct injection if this is the only way to get an engine to run on propane. Some concerns of mine are: Fuel line pressure, Fuel line back pressure, Fuel delivery time, Injection hole size(s), Check valve????

My current rig would be simple to change from intake to direct injection. The only thing that I would need to do is drill the injection holes through the main bolt. I actually started to do this and figured it would be wise to get some advice before I test it.

If anyone else has experience with this problem or direct injection please feel free to respond. I plan to post pictures next week. Hopefully of the engine running!

Thanks,
Dwenger

[Mark]

I really don't know much about pressurized fuel, but with any chemical if you pre-heat it or inject it into a firey mass, the stuff tends to burn exponentially faster. Then too you have to attend to fuel/air ratios, some substances are carefree and others aren't. Or if you provide the right conditions, most any compound will react with the right counter-part. You can make a rocket out of carbon dioxide and powdered magnesium for example, something postulated for propulsion on Mars.

http://www.space-rockets.com/marsjet.html

http://www.space-rockets.com/marsprop.html

Mark

[Mark]

I remember my brother demonstrating propane fired back upon itself with some 1/8 inch copper tubing coils contained in a long open-ended can. The sound was deafening and one would have thought to take cover for fear of an explosion. It was loud beyond belief and yet so simple.
I use to help fly a hot air balloon and the propane burner was kind of the same design only quieter by a large degree, still preheating the propane helps blast out the heat and you go up, up and away, flight in a different way.
Mark

[dwenger]

Mark,

Since I have had so many problems with pressurized propane, I believe I am going to try liquid fuel. I do have some questions about this as well. My design will be very similar to that above.

How is the fuel adjusted? How do you control how much fuel the aspirator delivers?

What fuel would be the best? What is the easiest to get to work?

To test the aspiration system can water be used instead of actual fuel? This would be just to see if the system works correctly.

What is a good injection hole size/area on the aspirator?

I am going to find the hardware I need and start on it tomorrow!

Thanks for your help!
Dwenger

[Mark]

I would try methanol, it is the best common fuel for not being fussy about the fuel/air ratio and just eyeball it as to what you think would be a good enough sized fuel hole to feed your jet, it's best to drill several small holes in some sort of bar or rod for the fuel to spray or rather be sucked into the engine like spars on an unbrella, a shower of alcohol mist spaced so that the fuel is evenly fed in from the vacuum formed in the throat.
If you sometimes spray in a few shots of alcohol up the tail of your jet and then spark it, the intial blast will create a vacuum in the throat and if your fuel level is tippy top level, you can watch the fuel pulse out and start to be drawn in when the jet goes bang. Sometimes you can spray a few shots of fuel in the throat for good measure too so that there's enough vapor to sustain the resonance until the fuel is sucked in. Big engines are hungry straight away, they need that fuel as suddenly as possible.
Mark