New member, lots of questions!!! JPX turbine
 

Hi everyone, I recently took a risk and purchased a used JPX T250 turbine off of ebay. I am new to turbine engines and have a few questions... any help would be greatly appreciated, I'm in desperate need of some education by those that have been around jet engines.

1. Does anyone have a manual for this engine? can't find one online anywhere.

2. Anyone know the spark plug size/code?

3. There are 3 oil ports, I'm assuming 2 are oil ports and one is a pressure return? How do I tell which is which?

4. I pulled the engine apart and inspected the bearings... they looked/felt fine. Does anyone know if the engine will need to be rebalanced since I took off the front compressor vane and rebolted it?

5. How much pressure during air start should I use at the regulator, i'm guessing in the 100psi range?

I have many more questions, but these would be a good start.

Thanks everyone:)

Dave

1. Can't help you there. I think you purchased poorly. I've never seen anyone use this brand engine before.

2. Spark plug? Do you mean glow plug. Any glow plug will work, but in my experience, colder ones may last longer, though they all do.

3. Oil port? Jeez. I've never seen a turbine with an oil port.

4. Yes, unless you replaced the items to their precise positions before undoing, you will need to rebalance it.

5. Yes, you need the pressure but I've started engines with 80 psi. But more importantly, you need volume. 5+ gallon air compressor.

Welcome and good luck!

That's an oldie.


I guess it's the 11lb thrust engine... but post a pic. As I recall, all the 250's were propane run, but there was a few converted to Kero.


Here's JPX's web site. I don't know if they have any info on it or not.

http://www.jpx.fr/Jpx/english/pg_t260pE.htm

Yea i dont know or anyone running those anymore, most are probably mantle pieces

JPX engines were made in France many years ago. They DO use a spark plug, which requires an ignition exciter.
It runs on liquid propane instead of kerosene based fuels, and uses a stainless steel fuel storage tank for the fuel. The tank was large and used up lots of room in the nose.
The real pioneer was Kent Nogy. He put one in a BVM Viper back in about 1996 or 1997. I saw if fly, and was impressed. BVM came out with the engine, and offered conversion kits
for some of the airframes.I don't believe an ECU is used either. I remember a servo controlled needle valve on the side of the engine that is rotated to increase/decrease the amount of fuel to the combustor.
It is an air start engine, and sounds really neat when spooling up....the starting whistling sound is much different than our electric start engines.
I think that the oil is contained in a separate tank and supplied to the engine by compressor bleed air, just as the old RAM 750 (Pre 750F engines) Back in the day I had S/N 042 RAM 750, and it used a separate oil tank. I had to refill a 4 ounce on board tank with turbine oil between flights. This might be the same drill on the old JPX.
My advice is to use it on your desk as a paperweight, and get a modern engine to fly a jet.
Back in 1998, I went to the meet at Fresno, and Kent had it installed in his red and white JR Bandit. I think he still has the airframe, but converted to modern power long ago.
That day he made his take off which was lengthy by turbine standards, and made a series of climbing circles to get to altitude. Bon Violett took off moments later with his yellow Bandit, and climbed his RAM 750 powered Bandit vertically to the same altitude. There was a very distinct difference in power between the engine types. The JPX was more like a ducted fan in power output. BV fave me my factory turbine training that day, which was required for a waiver. I went back home to San Diego Sunday afternoon.
When I got up on Monday morning, I called Patty and ordered a composite Bandit! I already had the RAM 750.
I am working from recall, and freely admit never having monkeyed with a JPX, so my recollections might be off somewhat.
A little later on, the JPX was copied in Japan (legally or other wise, I don't know) and marketed by OS and Sophia. It was a little too late, as the KJ-66 type engines were being produced by a couple of companies, and AMT was starting to make a presence in the USA..

Here's a link to a Sophia starting up (With the wind in the tailpipe no less!) http://www.youtube.com/watch?v=Am6ebi2tZzs

Here's a link to a JPX starting up. http://www.youtube.com/watch?v=M_HR8yPuCDw

Good luck!!

Excellent advice from a pro.

Unlike any other turbine of this days, this thing has a terrible thrust to weight ratio and can make you loose your eyebrows or worse.

Harley always has great advice.

Me and my dad flew this turbine a lot!. Both on a Bandit and T33. The best advice is what Harley just told you: mount it on the wall! it is very pretty to look at
We had lots of fun with it, but it was a difficult engine to operate. You need to be trained how to use it. Start up procedure was fully manual, needs lots of support equipment (pressure gauge, spark ignitor, air bottle, regulator, etc). You needed to play with the pressure at the compressor to know when to open the gas, then you ignited the engine at the right time, kept raising the pressure with air until it was running. It did use a lot of air, you would get 4 to 6 starts from a scuba tank.

Getting electrocuted by the spark plug ignitor was one of the fun parts of this engine !!!!!

And harley, you are right, it did not have an ecu. It was a servo operated needle witht a 6 seconds delay.

Propane fuel was fun too. You had to know how to fill up the tank. It was a full process from start to finish haha... can't believe we survived that era!

Now, once running, they were super reliable. No fuel pump. But you only had like 4 or 5 minutes. ANd throttle management made a lot of difference. That is why you see the old school turbine fliers being more active on the power... we had to, it was not a choice

Sorry you might have wasted your money, but I seriously doubt there are many people around that can help you. I for one, completely forgot how to run one.

Good luck

I remember guy have to place the plane way out of the way after a flight and vent the remaining propane. What a sight.

The throttle was basically a valve like on your gas grill. In the end I think they came up with some sort of EGT monitor but I think just for gross over temp.

Why did you take the compressor off? Did you mark how it went on the shaft beforehand?

And to me they did not really sound like turbines. More like someone shooting compressed air from a hose.

Welcome to the forum Dave, are you already an RC Pilot, or just interested in the turbine technology?

Hi all, I should have been clearer in my introduction... I have no intention of ever mounting this in a plane. I'm a mechanical engineer and have always been fascinated by jet engines. I had to have one to tinker with! I liked the look of the jpx, and didn't want one of the modern ones, jet cat for example, since I wanted the experience to be a little more involved than just hitting a start button. I understand this is outdated technology. It came with a JPX scuba tank, ignition module, propane tank and filling support equipment, temp feedback control box, oil tank etc. It's history was unknown, and the bearings felt like they had a little drag, so I decided to pull it apart immediately. I have to pull everything mechanical apart, it's a sickness :) The inside was clean as a whistle, and the bearings looked/felt perfect. I didn't realize they had such a high preload on them by means of a spring, that appears to be what the drag was I was feeling.

My intention is to mount it on a test stand, fire it up for 2 minutes every month or so, and shut it back down. probably sounds silly to a lot of people, I know.

Could I possibly convert the spark plug to a glow plug? I can't find a similar spark plug for sale anywhere. Not sure if a glow plug has enough juice at those high compression ratios.

Also, does anyone know of someone/some company that can balance it? Wondering if a crankshaft balancing shop could do it.

Thanks for all of your help. And I am in desperate need of a manual if anyone knows where I could find one.

I and sure most of people here understand perfectly, just running a jet turbine in a bench is also a cool hobby. Keeping this in mind I would suggest you not to send the engine to balance, just assemble the compressor wheel back to place and run the engine just above idle.. it is highly probable that there will be not any vibration or any issue and if the engine is running smooth you are good to go to higher rpm´s

Having a spark to glow plug conversion is a good idea, to get rid of the "tazer".. just be sure that the filament is pushed outward and it glows brightly.

You also don´t need a scuba tank at all, Years ago I saw a friend starting a JPX in Kangaroo jet, wich is almost a flying bench airplane with a exposed turbine with a small electric motor and a cup with a o-ring.. pretty much like a normal engine starter. If you would like to start it with the scuba, anything from 100 to 300 psi would work, pressure is not critical. The turbine only needs air to spin the engine, nothing more.

Inside the turbine, tipical pressures are about 10 to 20 psi.. the lubrification tank should be well sealed, and above the level of the bearings, so you can have good lubrification with this little pressure . The oil should reach both bearings, The better the lubrifications, the more the bearings will last.

Only start this engine outdoors, in a well ventilated area, in wich propane wouldn,t acumulate in case of a leak... also a big and handy fire extinguisher is a must. Remember to not get near the sides of the back of the turbine, wich are the most dangerous areas for being hit with shrapnel, in case of a wheel collapse.

Starting the engine is tipically this way.. Spin for a second or two the turbine, put the glowplug batt or turn the exciter on, open slightly the propane and wait for the "pop" of ignition while the turbine slows the spinning.. When your hear the gas being ignited, start spinning the engine at the higher rpm you can and increase slightly the gas until it reaches idle or slightly more RPM´s, running in its own.

If you see long flames coming out of the turbine, close the gas imediatly and keep the turbine spinning, until it clears out the excess fuel.. with some starts, you will learn the ideal ramp up of gas for starting it. Also always use eye and ear protection while you learn the basics.. also watch your fingers near the intake of this sucker.

This is just what it came to my mind remembering the old turbines.. feel free to make any question as I and most people here would try to answer them in the best possible way.

Hi erbroens, that was very very very helpful information. thanks!

Anytime, and this is how your glowplug filament should look for achieving ignition:

http://www.rcuniverse.com/forum/atta...mentid=2003499

Pioneer engine in the industry. I personally picked up Jacques (the J in JPX) from Palm Beach International airport in 1991 (or maybe 1992) and drove him to Frank Tiano's hobby shop for the first test run. It was run on a propane tank borrowed from MY GRILL ;-) and we borrowed a compressed air tank from my girlfriend's employer at the time. We had the engine running less than an hour after Jacques came through customs because we were all so excited. The engine was flown that same week in a Byron F-16 as a demo at Top Gun and blew everyone away, including BV who immediately sat down with Jacques to make a deal to work them into his line....the rest, as they say, is history!

For balancing you could try a local turbo rebuilding shop. We have one here that was helpful on an old motor I was playing around with.

Forgot to mention, some people start turbines using leafblowers.. it only takes a little practice to learn the best angle to achieve the most RPM´s;

Enrique, this works with AMT's, but as far as I remember, JPX's needed to spin really really fast to start. May be had to do with the fact that the turbine wheel is centrifugal instead of axial? and they also needed to be kept under pressure a long while after start up, so I would not try the leafblower technique on the JPX

They were definitely fun to operate!

Hello Jack, .. have seen even a souped up hair dryer do the trick some time ago.but I may be wrong.

Anyway I would prefer the electric starter method, as it is tidier. A electric motor with a high Kva that takes the turbine spin at 25Krpm+ will do it.

I agree with you, I think the electric motor, specially on a bench, is the best idea... I remember when we got our first AMT and saw how slow it spooled up, we thought the air line was clogged. :eek:

Did you ever fly one? you have been doing this for a long time!!! :)

Started tinkering with turbines since 1997, (with turbomins) and flown it in 1999 in my Roo. I think that this may be a incurable, mental condition. LOL.

The turbomin has many issues like the JPX, some of them worse than this. even so, It was great fun to fly it too. To this days, I think that there is not a turbine that sounds as good.

I remember seeing the auto-start feature of the AMT´s in Metropolis.. seemed almost like alien technology at the time...:)

Well, turbomin had kero start back then!!!! so it was also alien technology hahah. They were huge, i think they had some reverse flow or something, so the surface was always cold, remember?

good times... always fun to be at the leading edge of things

The good and old churros machine.. a case of hate and love!

http://www.rcuniverse.com/forum/atta...mentid=2003616http://www.rcuniverse.com/forum/atta...mentid=2003617

I have a 260 I purchased as a mantle piece I have a manual for it and all of the support equipment except for the pressure guage needed to set the max power limit (basically uses epr as the old jt8) and the equipment to fill the propane tank (has to fill from the bottom so the plane has liquid propane instead of gas). I have an onboard tank and bvm unit that is supposed to make it run easier. You may feel free to contact me at 307 514 3982 and I would be happy to offer any assistance I can. At the very least I can copy the manual and send it to you. There are some minor differences between the 250 and 260 but it will give you everything you will need.
I elected to never run mine because I purchased it because I enjoy the beauitiful craftsmanship of the motor and if a bearing were to go it would be junk as there are no parts available for it. Current production turbine bearings are of a different inner diameter and the shaft being hardened would have to be ground to make them fit, and that is in the very unlikely event that everything else survives intact.
OOPS sorry, missed the post that stated you had all the support equipment.