The cone will make the temp higher. The smaller the opening the higher the temp but the higher the thrust.

Last night i tried to run the engine again. It behaved like a spoiled child and did nothing i asked When it ran above idle speed the ecu had a hard time keeping the rpm's straight an it flamed out everytime. It did run nicely steady at 40K one time but then it shutted down directly, low speed error..... With or without cone made no difference. I could not see any rubbing but the noise was there every run. I took the engine apart and found that the glow plug ring had come loose. I did not like the way it was soldered but i had no hardsolder experience....... but that is not that difficult Tonight i cleaned the cc and ring and tried so solder them with silver solder and flux. GREAT! Better then i hoped Tomorrow i will run it again and see what happens

Was it soldered or welded? Did you braze it or actually just solder it?

It was not welded, just hard solderd (is that the same as brazing?) but very badly. My other turbine has a welded ring. This should hold very well since it is in the cold air flow and the plug and case conduct the heat. The silver solder i used melts at 610 degrees celcius so there are better options but i do not have better equipment.

Hello, I am looking to buy a used JJ Turbine from anybody here. I have various ideas on how to improve this engine and would like to have one to implement them on.
Thanks, Joe

What are your ideas? I want to try them I am going to modify the swirls first. My jj1400 runs at 560 degrees at 135.000, 600 at 140.000 and 800 at 160.000. To much an increase in the last part i think...

I have a new combustion chamber design, a new bearing tunnel design, and a different compressor wheel and NVG design that I machined. I used to work at Pratt Whitney a long time ago as a machinest on the real jet engines.

Mmmh... to much work. You build your own engine with jetjoe parts

nah, i have all of the programs and a 5 axis CNC.

Okee, very nice tool I want to improve the jj1400 with most of the original parts. I will modify the swirls this week so see the effect. Very simple modification.

Run at 800 at 160k? you got maximum thrust close to overheat. What's your modification on wheels?

I did not modify the wheels or anything else. If found a problem. The thrust cone is very very bad. Yesterday i ran without it. EGT results:
50K 440
90K 415
145K 464
160K 540

With cone at 145K it was 720

But without the tail cone, the thrust is likely very low.

Yes it is BUT with cone it should not be 260 more. Now that i know that it runs great without cone i know the tubine itself runs very nice. It runs very smooth and responds very fast to throttle accellerations. It doesn't heat up at all, almost no cooling was required after the test. In deaccelleration a have read an egt of 355. Temp changes are very quick and temp stabilizes very quickly.

So the tubine isn't a big problem, the cone is. I accept a temperature increase of 100 with cone but not 250. I will modify the cone so i run at 160K with an egt of 640. I will measure the trust when it is mounted in the plane (to be build very soon).

BTW, 800 is not near overheating, it IS overheating The NGV has melted at one point. Some meterial is completely missing......

That nozzle can be built to actually help pull the exhaust gasses out of the engine and at the same time increase thrust if designed properly with a built in apex. Kind of like the old Sophia turbines. If you keep working at it you will find the critical size at certain rpm and will have to settle for what works best for the entire range on that engine. What are the NGVs made of?

MACE

A single part nozzle is provided. I will make it shorter because that is the fastest simplest modification which everybody can do A double nozzle should do better and i will try to find one that will fit. Maybe i can use an inner nozzle of a wren engine. I can use the original outer ring and should not have any issues mounting it.

NGV is made of a hard steel, don't know what exactly.

NGV,s are made of 316 SS.

"they bend as you go"

cant believe this engine is out now for 4 years and still does the same as from the beginning.
mine is still on my workdesk holding down paperwork , so it cant blow away...

Hehe. NGV indeed bends like crazy but that is normall if you heat it up to 800 (+?) If it runs cooler i will machine it again to shape it perfectly round. It warped after last machining in 10 min Without the cone the ngv stays alot cooler so it should holdup with a better cone.

I cut away 7mm of the rear of the cone and got a EGT of 710 at 160k. Then i cut away 3mm more and got 680 egt. Much better but a total of 10mm is cut away. This will decrease thrust alot. I will try to measure thrust in a few days to see how it is now.

Also i use a Orbit fuel pump now and orbit fuel valve. Much better A test plane is being build to test the engine in flight.

you may want to try the standard (unmodified) 2 piece tailcone. If my memory serves me correctly, I get an EGT at 160K of 635 -650C with just over 13lbs of thrust, but that may be because of my altitude (4500 ft above sea level).

Hi all Jetjoe Owners
I have a JJ1800 with a flightworks 400b pump. I recently purchased the pump because people said that it is one of the best pumps around and that your turbine is as good as your pump, which is fair.
The JJ1800 had the Jetjoe pump on, and it has got 1 flight on and a couple of testbench runs, nothing over 70k. I never had a problem with the Jetjoe pump apart from that it would run a bit up and down at idle and the acceleration is a bit slow.
I put it the Flightworkspump without adjusting any of the parameters:
Full RPM: 115k
Idle Speed: 32k
Acc Delay 022
Dec Delay: 015
Stability delay: 100
Pump Start Point: Auto+2
Pump Start Ramp: 015
It ran perfect and I was happy. I mounted the turbine into my Skymaster Gripen and connected everything up. I wanted to start the turbine with the new Flightworks pump and the following happened.
The temperature shot up very rapidly and the pump voltage increased at a very fast speed. Before the temp reached 800 on the Data terminal I stopped the turbine. Smoke was coming from the turbine because of too much fuel entering the system. I also noticed that the ECU became a bit hot and there was fuel coming out of the solenoid because of the pressure generated by the pump.
I changed over to the Jetjoe pump and it started perfectly first time and ran perfect.
I decided to give it another go with the Flightworks pump and decided to change the parameters as follow:
Full RPM: 115k
Idle Speed: 32k
Acc Delay 022
Dec Delay: 015
Stability delay: 50
Pump Start Point: Auto+2
Pump Start Ramp: 003
As soon as I began the ignition phase the temps would go out of control and the pump voltage would increase passed the 200 mark whereby I stopped the turbine again. The fuel lines would swell up from the pressure.
I took out the Flightworks pump and ran it under no pressure at 2.4volts and measured the current it was drawing. The current measured 2Amps and the pump would run very unstable the whole time.
My question is this, can the pump be faulty, because it is drawing way too much current?

If the pump is drawing a lot of current and runs unstable - its probably faulty.

You should test the motor in the bench with the fuel setup as close to the one in the plane as possible. Even changing some connectors or adapters would influence the pump power needed and can result in a hot / wet start or a slow starting turbine. The ecu needs to adapt to changes so start with low values and work up. It's better to have a slow / not starting turbine than a hot one.

I have tested my jj1400 with cutdown 1 piece cone and it runs very nice. I build a plane to test it and have 10 flights on it so far Motor has about 5kg of thrust so that is a point to work on. It runs very cool (under 600 when it reaches 160K and then goes up to 660) and accellerates very quickly. It can handle an accelleration delay of 6 in the fadec when it is warm. When it has just started 6 is a bit to quick. I have set it on 9 and that is fast enough Plane weights about 8,5kg and is not fast but is flies very well. Motor starts very very good, just one small flame or pop during start. No hot temp's and a nice quick startup.

I have another jj1400 from a friend which had run only a few times but very hot and the ngv is completely destroyd. It is all black, cracked and warped. Metal has melted away at some points. The bearings are very bad and are gone. The o rings are melted. These is only minor rubbing damage on the compressor so it will run again soon. I have a original wren ngv and it is a perfect fit. I have high speed (172k) bearings to test. I also ordered a 2 piece cone and wil test with that one 2. I then have the original 1 piece, the cutdown 1 piece and the original 2 piece.

So i will test a stock jj1400 with wren ngv and high speed bearings and a 2 piece cone. I hope this is a nice combination and everyone can do this upgrade, no machining needed

with the fuel lines swelling and high volts and amps sounds more like a clogged filter or nozzles / some restriction after the pump.
the ECU/FADEC is trying to ramp up the turbine but the fuel is not getting in causing more volts to be called for.

Hi JetJoe fans

I just tested a second jj1400 that was damaged. I used the stock bearings from my jetjoe and used the wren ngv and the 2 piece cone. It now runs fine and sounds different but a lot better. During accelleration the temp rises to 610 but at 160k it settels quickly at 554. YES, 554 degrees egt at 160.000 rpm Very nice........ very very nice.....

My own 1400 has a turbine wheel that is 3/10mm larger than normal I will machine the ngv on monday to my wheel size en then i will test my 1400 with the highspeed bearings, wren ngv and 2 piece cone. If it runs fine also i will mount it in the test plane to test with the original ecu and tempprope ect to see if the values are accurate. I am now testing with the electronics from the 2e turbine.

If mine runs fine i will mount it in the test plane again and test it on saturday, if all goes well. If it runs ok i will try to run it 5k higher to get a bit more power out of it. The 2 piece cone looks very nice and runs great but has les power then the 1 piece. I don't know if it has less thrust then the cutdown 1 piece but i will findout when i fyl the plane