JP-20 Pressure Jet (Old Plans; not a Gluhareff)

[DBene]

Years ago I purchased plans from an ad in Popular Science or Popular Mechanics magazine (for $20, I think) for the "JP-20 Pressure Jet" for use with propane. I still have the plans; they are 11 one-sided pages of 8-1/2 x 11 photocopied sheets; there is no copyright notice on them anywhere. This is not a Gluhareff Pressure Jet. It is a linear design. I have found absolutely no references to it on the internet by Googling subjects like JP-20.

As I remember, the magazine ad was not at all specific either in general details or specifications, and neither were the plans, but the ad did infer that two of them could be used on the ends of a helicopter blade. I think that there was no hint as to thrust, materials to be used, spark starting, and etc. Maybe it was just a scam. I built one out of mostly welded mild steel sheet metal of about .050" thickness but have been to afraid to try it.

I wonder if anyone visiting these forums has built this and got it to working. I would be interested in any and all info or comments.

DBene
"If it ain't no fun,... it's no fun!"

[zono]

Dear DBene,

can you post us an image of your build or out of your plans, or total plan, if there is no copyright? Maybe then you get more answers.

zono

[DBene]

Dear DBene,

can you post us an image of your build or out of your plans, or total plan, if there is no copyright? Maybe then you get more answers.

zono

***
I broke out the plans. There is a sentence or two about things I said were missing. Still cannot find any copyright notice, though.

I can post a photo of my build today or tomorrow.

[zono]

Hi DBene,

please dont forget posting your images.

zono

[DBene]

I don't know how to post photos here...cannot seem to find out in faqs, etc.
So, I have posted a group of 4 photos at FLICKR.
--I hope that you all can see them.

The photos are:
1-PressureJet, http://www.flickr.com/photos/dbene/5015566287/
2-JetInTake1, http://www.flickr.com/photos/dbene/5015566289/
3-JetInTake2, http://www.flickr.com/photos/dbene/5015566291/
4-Spark-Fuel, http://www.flickr.com/photos/dbene/5015566299/

PHOTO: Pressure Jet
Shows the profile of the JP-20 Pressure Jet. The 2 D-Cell flaslight and the yard stick are in the photo to help give some idea of 'scale'.
This Jet Engine is about 32 inches in length;
--Burn Chamber is about 6" diameter;
--Exhaust Tube is about 3" diameter.

PHOTOS: JetInTake1 and 2
Show the Conical Fuel Nozzle supported by 3 sheet metal vanes welded to the Burn Chamber Inlet Orifice.
--The cone is threaded onto a 1/8" NPT pipe which extends about 8" toward the Exhaust Tube, where it turns 90 degrees to exit the engine in order to be the Fuel Supply Inlet.
--The Burn Chamber face of the Conical Fuel Nozzle is drilled so that 3ea. 1/8" holes 120 degrees apart, and angled toward the sides of the Burn Chamber, supply Propane (Gaseous or Liquid Propane) to the Burn Chamber.

PHOTO: Spark-Fuel
Shows the Fuel Inlet (with a cut-off rubber hose attached), and a Spark Plug screwed into a threaded insert near the start of the Exhaust Tube

Questions?

[zono]

yes, nice fotos !!! is there a flame holder inside? and a vaporizer coil ? i can't see any ejector tube or similar air compressor...

have you pictures from inside?

zono

[DBene]

ZONO...
The short answer to all your questions is "no".

It is pretty simple & straightforward. The only thing inside is the tip of the spark plug and the 1/8th inch NPT pipe which goes to the Conical Fuel Nozzle.

Apparently the "pressure" is caused by the burn ...captured & thrust to the exhaust by the tuning of the Burn Chamber geometry...

I guess I should make photos of a couple of the plans pages. Would that help?

[tufty]

Please do.

[zono]

yes, please do, DBene, add fotos or copies of plans please. Maybe you have a ramjet and no pressure jet ?

zono

[Mike Everman]

Dbene,
Posting photos is simple. Just look for the tab under the save, preview, submit buttons called "upload attachment", choose the file, add it, and just make sure it is 800x600 or less.

[DBene]

OK, sorry... my life got REAL busy. It has been close to a year.

I re-read the posts in this thread and the simple plans and the simpler instructions, and have a conclusion...

There is no help in reproducing the plans here, because the photos tell the whole story (if you can decipher my notes about them.

Evidently, to fire this thing one turns on gaseous propane, sparks the spark plug, waits for a bit of warm up, then inverts the propane tank and meters liquid propane into the engine. period.

What say, y'all?

[luc]

Hi,

Came across that topic and found it funy ...

Given what is shown and seems to be ... It could be called an "Incomplete" engine ... What ever type it is ... Or some sort of "Frankensthein, parts from everywhere" unfinished experiment ... And even more amazing they got 20$ for it.

In fact, looking at the engine's geometry, It can somehow or somewhere qualifies between, a) Maybe a Ramjet ... But then the exhaust is too long and it's missing a flameholder, b) Maybe a pulsejet considering the tail pipe and the air inlet ... But then, it's missing the valve and valve plate, and c) Certaintly not a pressurejet ... For it's missing to many components, although running the gas tube from the tail pipe to the front nozzle indicate the designer knew stuff about "Fuel evaporation" ... Hummmm ... Mysterious it is ... Mostly misterious indeed.

Anyway .... Your appreciation of "Scam" is probably the best description you've given it and just happy you only spent 20$ for it.

ORRRRRR ... Maybe it is your drawing set that is "Incomplete" and why this engine construction seems to be.

And Noooooooo ... Puting gaseous or liquid propane and sparks won't have it start, other then giving you big flames coming out both the tail pipe and air inlet. In fact, if you do so given the spark plug location ... Will probably scare you more ... He he he.

This said ... Why don't you finish since you're that far? ... This could be a good plan.

[DBene]

Hi Luc...Happy Saturday!
I got an email notification of your post here.

Well, I guess I am the only one who is willing to admit they got taken for $20 (around 1992, I think) for these plans. Sort of amazes me that I found nothing at all online about it.

It occurs to me that it might be meant to be a ram jet...or just a scam.
--If a ram jet, then it obviously, after your comments today, was meant to be spinning at the ends of heli blades either before or after ignition... ??

I don't know. It has turned out to be a big mystery to me. Maybe I will just lite it off one day to see what happens. But just now there are too many other things on my plate...other things seem to be more intriguing, you know?

Thanks for your post.

[luc]

It occurs to me that it might be meant to be a ram jet...or just a scam.
--If a ram jet, then it obviously, after your comments today, was meant to be spinning at the ends of heli blades either before or after ignition... ??

Hi again,

I like your approach about all this and obviously, you seems to be a very good "Learner" what ever experiences, funy or less funy, you encounter ... Cheers to your spirit and attitude ...

This said and probably being correct in your conclusion in regards of what the engine might be, here's a lead to information towards your conclusion and as I found a nice picture in my librairy on "Rotodyne". Push this word either in Google or Youtube and you will find alot.

Good weekend,