Lockwood Help

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Vaulter
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Lockwood Help

Post by Vaulter » Sun Oct 10, 2004 4:41 am

After reading through this forum and Bruce Simpson’s site for about a month, I constructed my own Lockwood Hiller jet. I started with Andreas Sunnhordvik’s design and the LH patent and changed it to have a 180 mandrel bent section instead of the two 90’s. I am using a very similar fuel rail as Bruce, right before the combustion chamber. When I try to start the jet I can get it to have a single loud bang, or if I get my blower right in the intake I can get a pretty health roar. With the roar the engine will actually begin glow red, but when I remove the air the jet dies. Could any one give me a suggestion, weather it be a different technique or a dimension I need to change. Thank you for your time.

Tim Hollman
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Bruno Ogorelec
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Re: Lockwood Help

Post by Bruno Ogorelec » Sun Oct 10, 2004 8:48 am

Welcome to the forum!

I am not a great expert, but have followed teh experiments of many forum mebers and they very often boil down to problems with the intake. The intake is the most important and critical part. For instance, have you made the intake mouth flare out, like the end of teh trumpet? This is a very important feature.

NanoSoft
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Re: Lockwood Help

Post by NanoSoft » Sun Oct 10, 2004 5:20 pm

If am reading your dimensions correctly, your CC has a dia. of 9 inches. If so this is a fairly good-sized pulsejet and your problem probably is that you are not giving it enough fuel. If you have the ability, a picture of the jet and a video of you trying to start it would help us the most in figuring out what the problem is.

Nanosoft

Vaulter
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Re: Lockwood Help

Post by Vaulter » Mon Oct 11, 2004 5:06 am

Thanks for the replies. Here is a picture of the jet. Also, I did add a bevel to the intake. It goes from 4 to 5 inches in about 3 inches of length.
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Vaulter
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Re: Lockwood Help

Post by Vaulter » Tue Oct 12, 2004 6:55 am

Here is a link to some pictures and videos of the jet. It seems to me that the jet is starved for air.
http://www.prism.gatech.edu/~gtg948h/PulseJet/

steve
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Re: Lockwood Help

Post by steve » Tue Oct 12, 2004 12:07 pm

After watching your video (and having built a lockwood of similar size) I can tell you with 99% certianty that your problem is that you are feeding it too much fuel. What you should do is gradually turn down the throttle untill the engine catches (if this requires a seccond person then get one!)

could you give us some details about the fuel system you are using and what sort of injector you have in there?
Image

Vaulter
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Re: Lockwood Help

Post by Vaulter » Tue Oct 12, 2004 2:57 pm

I used this design from bruce simpson's page. The hole go straight through the tube and are positioned so the fuel sprays twords the CC walls. The propane tank is up side down for liquid feed, and I have a simple ball valve in the line to caontrol flow. In the video I am trying larger amounts of fuel. I have experimented with low fuel, but get about the same results. Thanks for the reply.
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mk
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Re: Lockwood Help

Post by mk » Wed Oct 13, 2004 5:44 pm

Actually you're engine gets to much fuel.

(1) Try slowly to lean out the fuel flow (focus the "flame thrower" at the tailpipe outlet to a "conical blue torch-like flame").

(2) Try different air blower positions (distances and angles), eventually it might help adding a conical nozzle (smaller outlet diameter!!) to your blower

(3) If it does not help, try these steps (The intake cone might be the problem as well!):

-Cut off the intake cone.
-Make sure the intake is as long as shown in your plan. (...but wait: Has this engine, shown in the plan, already run in earlier days? Or are this just guessed dimensions? ...if [1]"yes" is your answer than go on as the following).
-Squeeze the intake a bit towards its outside opening (maybe in a vise), let's say about 10...15mm.
-Make a small "bell-mouth" like shown in the plan. Easiest methode: Bend the sheet metal ~5mm behind the edge with pliers along the intake opening outwards.

Good luck!
mk

hinote
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Re: Lockwood Help

Post by hinote » Wed Oct 13, 2004 6:28 pm

Vaulter wrote:After reading through this forum and Bruce Simpson’s site for about a month, I constructed my own Lockwood Hiller jet. I started with Andreas Sunnhordvik’s design and the LH patent and changed it to have a 180 mandrel bent section instead of the two 90’s. Could any one give me a suggestion, weather it be a different technique or a dimension I need to change.
I tried entering the dimensions into a Uflow sim, and the engine won't run. It fails to "flip over" into intake inflow during the 2nd half of the cycle.

Short of some considerable attention to altering proportions, my guess is that it won't run as currently constructed.

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

hinote
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Re: Lockwood Help

Post by hinote » Wed Oct 13, 2004 6:38 pm

hinote wrote:
I tried entering the dimensions into a Uflow sim, and the engine won't run. It fails to "flip over" into intake inflow during the 2nd half of the cycle.
Sorry to be so negative.

I went back to Uflow and tried changing the intake to a straight pipe. It begins to inbreathe a little.

It still looks like the proportions aren't quite right--but you might try substituting a straight pipe on the intake. Or, as others have pointed out on this Forum, you can also try squashing the intake to reduce its area.

Hope this helps.

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

GRADO
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Re: Lockwood Help

Post by GRADO » Sun Oct 17, 2004 6:31 pm

Hi,

I've built a lockwood of a similar size to yours which works okay.

The main difference between mine and yours is the size of the tailpipe/u-bend section, Mines 3" inside diameter.

I think you'll need to either change that section or make the inlet pipe smaller (between 2" & 3" diameter).

My opinion is not based on any scientific Knowledge just what I've observed.

Tell us how it goes.

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Re: Lockwood Help

Post by ZSartell » Tue Oct 19, 2004 10:42 pm

I agree with GRADO. It looks like your intake flare is too long (intake too short) and the smaller diameter of you tail pipe should be closer to 3". This is what I would change, but don't hold me to it. Good luck.

Vaulter
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Re: Lockwood Help

Post by Vaulter » Wed Oct 20, 2004 1:27 am

So I am pretty sure I have figured out my problem. It turns out that 2*pi*r is the circumference of a circle not a 180 degree bend. My original calculations did this correctly, but when I was assembling the jet I managed to mix it up. I am going to make the adjustment and will let you guys no how it goes. Thanks for all the help so far.

Tim

Vaulter
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Re: Lockwood Help

Post by Vaulter » Fri Oct 22, 2004 12:18 am

IT RUNS. Well kind off. I got the jet to sustain using vapor feed. After the spark and propane were removed the engine ran for about 45 seconds before I tried reducing propane feed to see if it would idle. The results being the jet died. After this short run the small amount of propane in the tank was frozen. I refilled the tank and tried again. Once the engine was running I increased the flow of propane and again the jet died. I think there is something in the tank itself (20 lb grill tank) that it limiting flow. Weather it be a safety valve or simple can not keep up pressure. The engine is always close to running on liquid, but has not sustained yet. Any suggestions? Video of the jet running coming soon.

Thanks,
Tim

francisco
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re: Lockwood Help

Post by francisco » Tue May 03, 2005 6:39 pm

hola, soy de argentina, queria preguntarle a vaulter si podia explicar bien lo que quiso decir, y lo que le modifico al modelo de el

podria fijar nuevos planos. estoy ancioso por escuchar a ese lockwood rugir.

"It turns out that 2*pi*r is the circumference of a circle not a 180 degree bend. My original calculations did this correctly, but when I was assembling the jet I managed to mix it up."



francisco cooreman

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"I DONT`T SUFFER OF MADNESS, I ENJOY IT CONTINUALLY"

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