Reed Valves for 110 lbf Globe/Solar Pulsejet

Ron Patrick · Post by **Ron Patrick** » Wed Apr 28, 2004 7:59 am

I have a Globe/Solar pulsejet. It's about 7' long and puts out about 110 lbf. It was made for the US military for a drone in the 50s. It easily started up on gasoline and ran for two 30 second sessions but after that would not start.

I took it apart and the reed valves are all deformed. There are two kinds of valves, 18 of one and 14 of the other and it shouldn't be tough to laser cut more of them.

My questions are:

1. What are they made out of? They look like stainless and are mildly magnetic.
2. Has anyone made a set of these valves?
3. Does anyone need a set of these valves? I guess I'll make a bunch.

Thanks,

Ron Patrick
Sunnyvale, CA USA

Stephen H · Post by **Stephen H** » Wed Apr 28, 2004 10:00 am

from what i know nobody on this forum has one of them. Sounds like a interesting pulsejet. The valves would be made out of spring steel and probibly reasonibly thin. if you look at www.aardvark.com/pjet the guy there has info on how to etch valves!

Stephen

Mark · Post by **Mark** » Wed Apr 28, 2004 1:23 pm

Ron Patrick wrote:I have a Globe/Solar pulsejet. It's about 7' long and puts out about 110 lbf. It was made for the US military for a drone in the 50s. It easily started up on gasoline and ran for two 30 second sessions but after that would not start.

I took it apart and the reed valves are all deformed. There are two kinds of valves, 18 of one and 14 of the other and it shouldn't be tough to laser cut more of them.

Ron Patrick
Sunnyvale, CA USA

Hi Ron,
Where did you get your engine? I would be interested to see the two kinds of valves. That seems like an interesting philosophy, you would think they would all be the same, do you think it is some sort of compromise for varying air speeds, some not so stiff for static starting or something? And lastly, why do you think the valves waffled so quickly?
Thanks,
Mark

Post by **Mike Everman** » Wed Apr 28, 2004 2:32 pm

Ron, welcome! I'm the guy that always says: "how about some pictures?"

paul skinner · Post by **paul skinner** » Wed Apr 28, 2004 3:06 pm

Almost sounds like one of these;

http://cgi.aol.ebay.com/ebaymotors/ws/e ... gory=26437

doesn't it?

:)

The info from the description at eBay;

A rare find, 1951 drone pulsejet engine.Has been in it's crate until today! Engine measures 75 inches long with an 8 inch nose and 6.5 inch tail pipe. rated at 110lbs thrust,the tags on the nose say it tested at 118lbs this motor is absolutely brand new,a true museum piece.Pulse jet engine technology was developed by the Germans in the late 1930's and was put to use by the * war machine in the Fiesele Vergeltungswaffe V1(Vengeance Weapon) guided missile, or "buzz bomb". the US copied the V1 and produced it's own buzz bomb called the Loon.this engine is a smaller replica of the V1 engine that was produced in the US and powered the Navy's Globe-KD2G Firefly target drone. Runs on gas and has all the fuel pressures on the tags, only about 10lbs to run it. very interesting piece of hardware,weighs 30lbs and has about fifty inspection stamps on it. I have more than one but may not put another on ebay. serious inquiries only at rrocketmann@charter.net will ship FedEx in us only.Payment in cashers check or money order only, engine will be shipped within two days after payment, please do not bid if you cannot pay within five days. No COD/escrow, check my feedback. Thank you!

Pieter van Boven · Post by **Pieter van Boven** » Wed Apr 28, 2004 3:20 pm

Ron,

Welcome to this Forum. If you have bought one of the "Ebay-Solar" engines you have a real beauty!
Could you provide us a sketch with the dimensions of the combustionchamber?
Thanks,

Pieter.

Mark · Post by **Mark** » Wed Apr 28, 2004 4:26 pm

I wonder if it was heat that took its toll on the petal valves? That if it were in flight, ram air would have wicked away more heat perhaps. I'd like to see a picture or scan of the little petals and if you could micrometer them so we could know what thickness they are.
I use to quickly remove the head on some of my homemade pulsejets after running because the thick red hot plumbing pipe would transmit the heat to the delicate reeds when the cooling from methanol and air stopped.
It must have been fun to start your engine up though, too bad the reeds gave out so quickly, maybe a constant spray of water over the engine would help if heat is found to be the cause.
I am with Mike, it would be very interesting to see some pictures of the valves and how the assembly is all put together.
Mark

Pieter van Boven · Post by **Pieter van Boven** » Wed Apr 28, 2004 5:30 pm

Ron,

Is the Solar engine fitted with mixing venturies just like the Argus engine (see picture)?
Take care if you cool the engine with water. If you cool the materials to quickly they might get damaged! You don't want this to happen to such an engine.

Pieter.

Hank · Post by **Hank** » Wed Apr 28, 2004 6:36 pm

Hello- Perhaps an upgrade in the material your valves are made of is called for. I'm certain the longevity of these engines was not a consideration. Using a fuel with a lower caloric value might help with valve life. Gasoline has the highest caloric value of currently used liquid fuels, right behind Hydrogen. The Germans developed Anatol as a fuel for their Argus engines. It was a Coal Tar derivitive. Instead of the 19,000 BTU jolt you're running try a mix that gives you 16-17,000 BTU (Diesel).
Dirty burn fuels work well due to their ability to retain heat and greater mass during the compression part of the cycle. The fuel is , however, more difficult to ignite in a cold engine.
How did you aquire this engine?
Hank

Ron Patrick · Post by **Ron Patrick** » Wed Apr 28, 2004 8:31 pm

1. Valves are 0.010" thick and now I learn that such valves are made of blued spring steel. If I make a 10 sets, I won't care about the short life but I bet I can improve on that.

2. Bought it off the guy who was/is selling them on eBay. Paid $1500 but bought an "out of box, dented one". I took it apart when new and the valves looked all the same, not deformed, not discolored and it did start up really really easily.

3. Fuel is sprayed in along a rectangular fuel loop made of 1/4" tubing that is about an inch downstream of valve exit. About 5 holes a side (20 total) about 0.005" dia. but I'm guessing here. Targeted 9psi at the engine although it would run from 4 to my max of 13 psi. Did about a gallon in a minute.

4. Combustion chamber 8" dia and 19" long, tapers to 5 1/4" dia over the next 16" and 37" of tailpipe after that. Humm, so I guess that makes it 6' long.

5. On the front of the engine, behind the fuel loop they have a 1/4" npt plug leading inside the housing to two 3" long tubes that point circumferentially around the i.d. of the 8" dia tube. If I put air in here, it would cool the walls and reduce the wall heating to the valve body. But it does not look like that's how they got too hot. Maybe that 1/4" npt plug is used to start the engine. I am starting to suspect that I might have melted the reeds because I didn't put a slight downwards tilt on the jet so any liquid fuel would drain out. Looking in the front when it was running showed that the burning was occurring just behind the valves (i.e. 1" or less).

6. I have enclosed a picture of the partially disassembled valve body. The pattern of the reeds taken out is repeated 7 times: plate with one reed, plate with 3 reeds, spacer, plate with 3 reed, plate with one reed, aluminum spacer. The aluminum spacer has a triangular cross section and the "one reed" plates can seal against them. I think there was about 3 mm spacing between the back edges of the two one reed plates that sealed against the aluminum spacer when the engine was new and not running. I cannot recal much about the 3 reed plates bend and clearance when new.

7. So from from the sounds of it, I am all alone in having run and burnt up this particular engine.

Best regards,

Ron Patrick

Post by **Mike Everman** » Thu Apr 29, 2004 2:10 am

Ron, that's a great post, man. Loving the detail! I wonder if just time took their toll on the valve material. Hydrogen embrittlement leaps to mind. I remember the term, but can't remember if it is appropriate here. It certainly does look as if they got too hot, though. Was there a manual?

Ron Patrick · Post by **Ron Patrick** » Thu Apr 29, 2004 2:50 am

Nothing's brittle here, I just toasted the valves and they bent every which-way. Get something 0.010" thick hot and it doesn't take much to bend it. Heat discoloration everywhere. The surface looks like a rainbow.

There was a tag on it saying it could be run from 4 to 13 psi (true) and that at 9 it put out 110 lbf. That's all.

Ron Patrick

Mark · Post by **Mark** » Thu Apr 29, 2004 2:57 am

I noticed on some of my primitive experiments that when I ran some pulsejets lean, perhaps akin to your 4 psi range testing, my reeds suffered and warped, they didn't get enough cooling, and the reeds showed signs of heat discoloration and warping.
Thanks for posting the reeds and how they go together. It shouldn't be too hard to make new reeds.
Mark

http://www.use-enco.com/CGI/INPDFF?PMPAGE=711

This is a good place to buy blue tempered spring steel. I have purchased several thicknesses from them, they usually ship the day you order and Enco has low prices.

Anthony · Post by **Anthony** » Thu Apr 29, 2004 3:00 am

Would my concerns about the fact that it's a target drone pjet be justified (see "Off Topic" topic)? I'm sure you can change that by making new valves from better quality materials... But as you don't seem to be concerned by valve lifetime, I think you made a nice buy here.

evildrome · Post by **evildrome** » Wed Aug 04, 2004 11:58 pm

Ron,

Have you got any mor details pics? Especially the valve supporting ribs.

Cheers,

Wilson.

www.pulse-jets.com

Reed Valves for 110 lbf Globe/Solar Pulsejet

Reed Valves for 110 lbf Globe/Solar Pulsejet

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