Bruce Simpson

[jetbill40]

That had to be cool.They come through our neighborhood through the summer and fog they sound neat. Hold on boys I will be getting imfo for my engine soon.I am putting it on CD so it will be availible and I promise I won't pull a SIMPSON! JET BILL

[tufty]

They come through our neighborhood through the summer and fog they sound neat.

The dynafogger is a very neat package, perfect for what it does. One of these was the first pulsejet I ever got to play with 'up close and personal', on a summer job working for a pest control company. Used to use it for disinfesting big grain stores where the sprayers wouldn't reach. Had 'dalek-like' heat shielding over the tailpipe (a wire grid, you have to have seen early 70s 'Dr Who' to understand what I mean I guess) and made a helluva noise. Loads of fun, one of the things that made a crappy job tolerable.

Simon

[Mark]

I remember seeing a military model on eBay that was used to disperse crowds, it sprayed tear gas instead of insecticide. I bought a very old smaller pulsejet fogger that you slung over your shoulder. It was used to kill mosquitos in some city park in Nebraska the seller said. It looked like a typical pulsejet only the tail pipe was about 3 times longer than normal and the insecticide was introduced about a foot from the tail end. The intake was longer too and inside the combustion chamber there was a thick coil or spring of wire to store heat or something, the pulsejet looked like a valveless with a flat face and snorkel intake, (Schubert-like). Then upstream of that at a 90 degree angle was a petal valve.
It too, as Simon says had a grid of wires and loops like smooth barbed wire to keep you from accidentally touching the exhaust tube, which itself was jacketed with a larger tube as well.
Here's something similar from the Dynafog site.
I once removed the exhaust tube from a Dynajet sized plumbing pipe pulsejet I made and put/screwed on a much longer length of exhaust tube just to see what would happen. It became quieter and the heat moved from the combustion chamber further south to the exhaust tube. It amazed me that it would still run so bogged down but it did. I think it was about 5 feet long with a Dynajet sized combustion chamber.
Mark
http://bugsource.com/golden_eagle_thermal_fogger_.html

[Eric]

Check out the specs on that golden eagle fogger. If those numbers are right how can anyone even hold onto it, that would be like 60 pounds thrust, although it would be fun on roller skates.

Im afraid 30 hp with 1/2 gallon per hour fuel consumption would either make this the worlds most efficient pulsejet, or all their calculations are off by a factor of 10.


Model #2610, Series 3
Complete with instruction manual
Batteries
Auxiliary start cable
2 cleanout brushes

Type - Oil Based
Thermal aerosol fog
Resonant pulse principle

Formulation Output: 0-9 gal/hr, or 0-34 liters/hr, over 57,000 cubic foot (1600 cubic meter) effective fog per minute.
Engine Performance: 30 Hp, or 22KW , or 18,900 kcal/hr.
Fuel Consumption: 0.5 GPH or 1.9 liters/hr
Weight (Empty): 19 lbs. or 8.6 kg
Weight (Full): 27 lbs. or 12.2 kg
Fuel tank: 1.2 qts or 1.0 liter

[larry cottrill]

Eric -

They're not talking about equivalent MOTIVE power - the power they're calculating is the mechanical value of heat.

Back on the old forum, I commented on how 'weak' my Black and Decker Leaf Hog [electric blower] seemed compared to my Dynajet running, in terms of air movement. Somebody calculated that from the fuel consumption of the Dynajet, it was using up over 87,000 W of power! Obviously, on a small pulsejet, the VAST majority of the power is delivered as waste heat that has nothing to do with moving air through! The Dynajet is supposed to be roughly equivalent to a 2.5 HP piston engine with a propeller of reasonable efficiency.

L Cottrill

[jetbill40]

Heat loss as you know is the main reason why pulse jets cant run to there full potential.If you could harness the heat escape without melting the pipe it would be a power house. Jet BILL

[Bruno Ogorelec]

Heat loss as you know is the main reason why pulse jets cant run to there full potential.If you could harness the heat escape without melting the pipe it would be a power house. Jet BILL

It is more complex than that. You have to retain the heat instead of letting it transfer to the outside, but the heat must also convert into useful mechanical ‘push’. This is not easy to accomplish.

The conversion takes place as gas expansion. Gas takes on heat, expands and accelerates down the tailpipe. This is good, as the thrust increases with gas speed, but it is also limited. Acceleration can only progress up to the local speed of sound. That is the practical limit.

(Pushing beyond sonic speed is a whole new ball game of great complexity, which is just not attainable to pulsejet builders and I will ignore it here.)

If there is more heat available (which is usually the case in pulsejets), it has nowhere useful to go. This is where the design should provide more fresh air to be heated and expanded. The problem is that no one has found a really good way yet to introduce this additional propulsion mass without disturbing the working cycle.

So far, the utilization of excess heat has been limited to the addition of thrust augmenters after the end of the tailpipe. But, that is a long way downstream. The heat liberated from the combusting gas before the augmenter is still wasted.

Tests at the Rensselaer Polytechnic have shown that the introduction of more fresh air into the combustion chamber or close to it 'waters down' the cycle and lowers the thrust instead of increasing it, so that is obviously not teh answer. The same would probably happen with water injection (which is the idea that often occurs to people new to pulsejets).

I think that the heat should be used to pre-heat the incoming air. I would try using the same amount of fuel with a lot of heated air instead of a small amount of cool air.

Heated air should not 'water down' the process. It will allow the use of the relatively lean mixture, which will allow the engine to shift a greater amount of air with the same amount of fuel, increasing specific thrust.

Pre-heat would also make the outer casing of the engine somewhat cooler, rather than red hot, as all current pulsejets are.

One of my favorites is the Reynst pot encased in a Dynajet-style casing, with fresh fuel-air mixture flowing around the chamber and getting heated before being ingested. I would make the chamber finned like a cylinder of an air-cooled engine, so that as much heat is transferred to the passing mixture as possible.

There is some controversy over the concept. Some forum participants fear that the mixture will get ignited before entering the chamber, for instance. I think not, because the pulsating nature of the flow will prevent it (as I have argued elsewhere in the forum).

Others have argued that the pulsating combustion process requires a great heat gradient between the incoming mixture and the outgoing gas. This must be true, but I truly doubt that raising the temperature of the incoming charge by, say 50 or 100 degrees Celsius will change the gradient that much, given that the combustion temperature is some 2500 C and the average temperature in the combustion chamber probably around 1000 C.

[richardurwin]

I would like to add that I too have purchased (August 2004) one of the acclaimed Mr. Simpson’s Pulsejet CDROM @$39 + $7.50 P&P; yet to receive NO CD-ROM and NO Response to date to my emails!

Even though the guy has one of the best PULSEJET references on the web; I would suggest buyer beware, and steer clear!

[darrel.h]

I think he is dead. I read sometime ago that he died in a slip and fall accident in his home. His form contact system seems to prevent spammers and me from contacting him.

[marksteamnz]

I think he is dead. I read sometime ago that he died in a slip and fall accident in his home. His form contact system seems to prevent spammers and me from contacting him.

If you can't quote a link, please don't post stuff, it's just more miss information and a waste of space.

Bruce is still running www.aardvark.co.nz and unless he's posting from the abyss I'd say he was alive yesterday 24/3/06. You won't be able to contact him as despite having a good PJ site, he's caused problems for lots of people.

[pezman]

The rumour appears to hold true in the 11th dimension, from whence the post came.

I have posted the relevant link below. Those of you browsing in higher dimensions should have no problem following it:

Bruce Simpson in the 11th Dimension

[jthompso]

I ordered access to the online pulsejet book from Bruce Simpson about a month ago, and after two weeks of waiting I got fed up. I sent e-mails to him through every channel but never heard a response. Eventually, I did a whois on his website and found his home phone number and address, so I made a long distance call to him and spoke to him. He told me he would work everything out, which he didn't. Ultimately, it was only applying for a refund with paypal that seemed to shake him, and he sent me my password and access to the website. Bruce will deliver product, you just have to really get after him.

[dynajetjerry]

Mark,

The sole employee of Bill Tenney's Aeromarine Co., Charles Marks, is the person who created the first of what became the Dyna-Jet line. That was in late 1945, after Charles heard and was inspired by the operation of a WW II V-1 engine at Wright Field. (Aeromarine was in Harshman House, across the highway from the Field.) A long-time and close friend of Tenney, Charles had been hired to aid in the development of "a new, more advanced, type of 2-stroke engine." However, his pulsejet efforts (unknown by Tenney at the time,) were modestly successful and led to the temporary abandonment of piston engine work.

Tenney admitted to me, many years later, that Charles' "secret" jet work annoyed him at first, but its operation led him to agree to help in their investigations of miniature pulsejet designs. James Kloth and a few other employees of G. M. Gianinni in CA were already working on a small version of that company's 8 in. - 10 in. pulsejets for the military. It became the "Minijet" and was offered for sale in 1946. The Dyna-Jet was first advertised a few a few months later but production of the final design did not take place until early 1947.

Both Marks and Tenney passed away in the early 1990s. I've always been sorry I never met or knew Charles because, according to those who worked with him, he was a very intelligent, inquisitive, and talented man. He left Aeromarine in early 1948 but rejoined Tenney, in MN, a few years before his death.

Jerry

[Hydrazine]

Question: Has anyone had any dealings with this guy.I sent him a payment 8 mths ago and recived nothing. JET BILL

I wish I found your post a week ago.

I got ripped too.

[Rocket Man]

All I wanted to do is build the gocart any chance you could help me out? JET BILL

A jet is a speed engine not designed to go as slow as a go cart. Would you put a V8 engine on a rocket? NO WAY.

OK, I admit the project would be fun to build but not practical at all. Basically a total waste of time unless you just want to do it for fun. Are you willing to ride a gocart at 200 mph?

I have built a lot of projects over the past 40 years and several were gocarts. A 100 lb trust engine on a gocart is very slow take off. It will get you up to about 100 mph top speed but that will take a whole mile of flat level road with no head wind or curves and several minutes to get up the speed. It can be fun at first but it gets boring pretty quick.

If you want a FUN gocart build this. http://home.earthlink.net/~gary350/gokart15.jpg

This is my 3rd gocart like this I have built. It has a 4 cylinder 65 HP mercury outboard motor engine producing about 70 HP. It has a radiator up front to water cool the engine. It has a toyota water pump geared to the back axle to circulate the water. It has a disc brake from a Toyota truck. Engine RPM is 7200 wide open. The engine is geared 3.7 to 1 direct drive to the back axle. Push to start. At a rolling speed of about 5 mph punch the gas pedal to the floor and it will do 87 MPH is 3 seconds. Hang on tight the G forces will pull your hands off the stearing wheel. You can change the gear ratio to go any top speed you like. It will do 150 mph in just a few seconds. It will do 200 mph if your crazy enough to ride it. My top speed was about 180 mph back when I was young and stupid. The total weight of this gocart is 218 lbs.

You can buy old junk mercury outboard engines for $50. each remove the power head and build a gocart.

I lost all my photos when my hard drive crashed lucky I had this photo uploaded to my web page.