RE: JetJoe OWNERS thread
 

Chris

Nice, its looking good for that first run up[8D][8D] the sun glasses indicate better weather than we are having in the UK.

Paul
RCdriver

RE: JetJoe OWNERS thread
 

Yes the weather is almost fine for flight.
Ocasionaly there are dense clouds that make planes look like shadows
but overall it is not bad for March- April (It is the summer heat i am afraid mostly here).
I want to get it right from the start so although i could start it as it is, i am waiting
for those 50 micron fuel filters for gas and fuel.
I also final tested all of the auxilliary parts like the pump, pulled out the glow plug's coil and tested that the starter
spins the turbine as per fadec settings etc.
Btw i managed to get hold of some Jet A1 fuel and oil although i had to take it from a
airport refueling station in raw condition(not canned).
I guess that since the oil is good for an Airbus A300 it will be good for the jj1400 also...
Chris

RE: JetJoe OWNERS thread
 

I ran my JJ-1400 today for about 5 minutes, it's started fine idle at 45K rpm 680ºC goes to 160K rpm with 620ºC and 480pwm (pump), but it's begun to lost rpm and stop, when the starter tried to cool down the engine the shaft was stack, so I decide disensamble and inspect the engine but everything looks ok, the only thing is that shaft is decolorate showing that there have been lot of heat where the rear bearing is, my question is, is this color normal??? and if not what could be the problem???

RE: JetJoe OWNERS thread
 

Are you saying the shaft was stuck...siezed ...sounds like it.... and yes it looks like there has been a lot of heat where the rear bearing is. No this colour is not normal. I'm sure rcdriver22 or someone will be along later and tell us what the problem could be.

RE: JetJoe OWNERS thread
 

Hi.
I am afraid that i dont have the required knowledge to help you but out of curiocity,
how much operational time did this particular turbine had before the event?
When you say that everything looks ok that includes the rear bearing also?
I can't imagine how the rear bearing could get out intact after this.
What type of oil did you use and what exaust cone do you use, the two piece or the one piece?
I am asking all those questions because i am about to fire up my JJ1400 for the first time and i am a little concerned after i saw your post.
Btw i may not have the knowledge yet (in turbines) but this color surely does not look normal.
Something overheated badly.
Chris

RE: JetJoe OWNERS thread
 

Did you mix oil with the fuel?

Dave

RE: JetJoe OWNERS thread
 

airbuspilot2

If you are lucky, while there has been some short overheating, even seizing up, if the bearings are turning still you might just be OK. Say on a bad wetstart the heat is such that things can lock up to the starter will not turn at all, as it cools, it may turn again and then cool off with the starter. This could be the turbine wheel over heating and binding up onb the NGV.

First guess is that lubrication feed from the festo Y is blocked up, as these are even finer that the hypo needles into the chamber. Some jet guys put their last filter into the lube by pass line to avoid debris here as it is critical to bearings turning 160k when running.

As the engine is stripped, try to feed fuel/oil onto the metal lubrication line to observe oil/fuel being sprayed onto the front bearing, if its blocked up try removing the back plate to the diffuser and removing it. Back pressure or increasing the opening to clear it will allow the bearings to be feed a good flow oil/fuel mix to remain both wet and cool. Hope this assists you.

Paul
RCdriver

RE: JetJoe OWNERS thread
 

airbuspilot2

The color of the shaft was not too bad when you consider your particular turbine appears to be running 100c hotter than any of mine across the whole temp range. I think Carlos will have seen a few more like this. Given also that the turbine wheel transfers heat into the shaft and the rear bearing is in the extreme temp position of combustion chamber its going to be blue, more extreme is that discoloration much further along the shaft indication long term misuse or overheating problems.

Paul
RCdriver

RE: JetJoe OWNERS thread
 

Hi,

I have to said that probably it was my mistake, I used fuel mixed for an Artes Jet engine just 2.5% Aeroshell oil. The bearing looks fine and I am going to try to restart it tomorrow. Any advice would be better to run just at idle or something???, How to know if the bearing is damage??? because look fine and run free now but when the engine was hot the starter can not move the engine but it turn with hand.

Thanks

RE: JetJoe OWNERS thread
 

Bearings[&:] On the shaft do the bearing spin totally freely?? As flat spots interrupt the spinning. Rebuilt in the case does the shaft should spin freely for 2-5 secomds? Then you are probably fine to run up. The oil content of 2.5% is not a problem but it is the 'flow rate' onto the front bearing, double the rate and you are then at a 5% content etc, etc.
Temp sensor and readings. Is it in a hot spot? move the hole round a space or even 180 degrees. The tip is into the about exhaust 2-3mm? and the distance from the wheel is important and JJ had to change it. Then if it still the same readings it is a CC problem and you are looking for an inconel replacement.

I think you might be a big bird Charlie Papa Lima [8D] or even a AFI. Only here on RCU experts (mostly 14 yrs old) blame anything at all but themselves ie their cat or mother. ;)

Mix a special small brew of 8% to try running it up again. Itsmuch easier than flairing onto the keys:)

Paul

RE: JetJoe OWNERS thread
 

Paul do you think that i also should mix a small amount of fuel using 8% oil for the fist run?
I am going to fire it up today as the filters and propane valve are here and installed on the motor.
In fact the only thing left to do is decide to fire it up as i must admit that i am a little
intimmidated by the videos i have seen [:-]
Ohh Yes i slept with it:D:D:D
Chris

RE: JetJoe OWNERS thread
 

Chris

Go for it, honestly you'll be fine with 5% it is a rare problem mentioned above. Spin the turbine up, give it gas and as it slows it goes pop! [:-] Turn the gas up as it can be blown out. The pump starts pumping fuel, you might see it the first time going along the feed line, its possible to prime the line by leaving the stick at full throttle for about six seconds but don't let it fuel for longer the 2-3 seconds. When the fuel hits the hot gas it spits and roars a bit, as you watch the revs going to 25k you think thats really loud ;) until it goes onto about 55K then you can't hear your buddy on fire duty without shouting at each other:D. When you run it to 160,000 rpm thats when you commit to ear defenders and worry about the people nearby[8D][8D] Great rush, can't wait to hear you impressions today.

Paul
RCdriver

RE: JetJoe OWNERS thread
 

Thanks Paul.
I will post my impressions later:D
Chris

RE: JetJoe OWNERS thread
 

Hi Paul.
I tried to fire it up but there is no ignition of the gas.
I tried several types and i could see the gas coming out of the exaust but no ignition.
I checked the glow plug and it looks good.
Any thoughts?
Chris

RE: JetJoe OWNERS thread
 

I had lot of problems with gas at first but I installed a restrintion in gas line, now the gas POP all times.

RE: JetJoe OWNERS thread
 

Pull the plug's element out some more (if you are getting a nice, white hot plug). Try again. If that does not work, try lighting the gas at a low RPM, at the aft end of the turbine with a propane torch. It works and is OK just for bench testing.

RE: JetJoe OWNERS thread
 

Hi Paul,

Do you think my timp reading are too high (680ºC at idle 620ºC full throtle)?, About temp sensor is around 2-3 mm inside the cone but is in the original hole that JetJoe made, so this should be closer to the turbine?.

My engine is about one year old and has two hour running, do you think I have to change my CC for an Inconel one?, where can I get a new inconel CC?.

Last question, there is someone in UK that fix JJ, is that you Paul?. I have two JJ-1400 and I want then running fine.

Regards,

RE: JetJoe OWNERS thread
 

Yes it ignites now every time by raising the glow power to 60!
What a nice sound....
I will now go down to the field to actually run this thing.
I will report back.
Chris

RE: JetJoe OWNERS thread
 

Been out flying this morning, its a real spring day here in the UK. Just back in and about list the fixes but you are already there:):)

Paul

RE: JetJoe OWNERS thread
 

It might be best to answer this partly here to assist others and in a PM back to you. On an average I'd look for 560-580 on a low idle dropping down to 520-540C at max rpms.
Outside that range which applies to many makes and types I tend to suspect running problems.

The higher temp could an assortment of factors. A year old JJ would be about #550 on the manufactured list and possibly left China without the upgraded combustion chamber inside. Though over a year old I know Joe will usually send out a replacement inconel CC unit.

The temperature probe hole is OK at 10mm to 20 mm from the NGV-turbine wheel and at a 9 to 3 o'clock position is fine. The higher temp is a possible indication of poor fuel and air mixing, as mentioned earlier on this thread, from degradation of the sticks inside the CC.

I am not attached to Joe, except as an owner, the previous UK rep Andy certainly assisted me and continues to, we remain friends exchanging technical running information and various ideas. I am not an expert but a home turbine builder. So in trials I got one JJ running below 480C at top rpm by adaption to allow even higher rpms by this cooler running and better mixing. I'm making new diffusers for my JJs (I had four at one stage) to increase the output above 14 lbs maybe to 17 lbs based around GTBA data and published papers.

I'd always say that if you can change a car tyre or can take an IC engine to bits then its worth while, after the guarantee period, of taking one apart just for the experience.[X(][X(] At worst you will have a bag of bits for someone to rebuild:D saving him 30 minutes of paid time stripping it down;)

I'm happy post to you (if you don't have one) a data retrieval FADEC to USB computer cable in order to down load the last 51 minutes or so of running data on to a computer and disk. This will provide a valuable insight. Either then post the cable back to me or buy it through paypal or I may send another user address to forward it on to.

Paul
RCdriver

RE: JetJoe OWNERS thread
 

Here is my report:
My first attempt was a succesfull failure.
The motor started the first time at once, reached idle and at full throttle the max rpm recorded is ~130000.
I wait for the motor to cool down with the assist of the starter and after 10 minutes i try again.
This time gas iginition was harder and the rpm reached 30000 quickly but it took very long to reach idle.
Full throttle again and the max rpm still 130000.
Then i returned to idle and back up again but this time i had a flameout.
Motor off, wait for it to cool down and i try again.
This time it took for ever to ignite the gas and reach idle and the idle speed was fluctuating +-2000 rpm.
Then i increase rpm but the motor wouldn't increase rpm past 70000 and then it flamed out.
It looks that every time i was trying to get it running it was becoming more difficult.
After 3 times the battery was empty so i packed my things and returned home.
On all trhee runs the EGT was 720 Celcius which seems too high i think.
The thermocouple is in the exaust cone by 2,5 mm

The bearings are fine there is no friction what so ever so probably one of the following things is not right.

1) My Fadec settings are wrong (Flight works pump)
2) The battery is not good as i only get 1200 mah out of 1800 mah cells.
I will replace it with 6 GP 3300 Nimh cells.
3) I think this must be the real problem here.
I used a 7% fuel wich did seem a little difficult to burn.

I also observed that there was fuel coming out from one socket screw that holds the outer exaust cone
I will recheck the fuel lines also.

My Fadec settings are:

max speed 160000
idle speed 47000
stop speed 30000
max temp 800
min temp 100
pump start point Auto+2
start ramp 2
acceleration delay 15
deceleration delay 15
Stability delay 50

Chris

RE: JetJoe OWNERS thread
 

Chris

Thats a result in part and at least you had it running today. On a good pump auto+0 should be good on a brand new pump of this quality. The ramp up is set too low try 4 then 6 for the next starts. A few things may be happening the battery is under pressure on start up, with all the functions being called upon. If voltage isn't there is affects the pump and therefore fuel delivered, also glow plug doesn't get enough at the very moment you want it to. Good move to go with 3000mah cells. Was the gas fully off after returning to idles? as if propane is still being feed by say a sticky valve the temp increases and is higher than normal. At above 100000 rpm anything above 700C indicates problems as EGT should be dropping visibly on the readout and no flaming as such be present from the exhaust.

Paul
Rcdriver

RE: JetJoe OWNERS thread
 

Hi Paul.
I think i found the problem.
There were 3 persons there but after spoting some bubbles in the fuel line, nobody thought of checking the two piece fuel filter.
The filter was unscrewed almost completely and ready to fall apart so it draw air also.
Probably air in the fuel is not a good thing...
The battery is not up to the job also.
Yes i manualy closed the propane gas after reaching idle just to be sure.
The first time the turbine started wonderfully and everybody was very pleased.
Actualy the first run was a success with no fires and no vibrations what so ever.
The only problem i saw was the air bubbles in the fuel lines and that it didn't reached max rpm (130000)
Probably later the battery started to fade and the fadec settings were off by far.
I am sure now that with a stronger battery and bubble free fuel everything will go fine.
One more question, Joe gave me a 6 cell pack, but do you think that a 7 cell pack would be better?
What do you use?

RE: JetJoe OWNERS thread
 

The air in line will certainly give problems to the point of 'flame out'. For manual start I use the 6 cells but for full auto FADEC I use either 7 or 8 especially when flying for a good session.

RE: JetJoe OWNERS thread
 

Ok I solved the problem of air bubbles, now the fuel is very air free (it was the filter).
I tried to start it in my house:D but it only reaches 30000 and a blue flame just makes it on the back.
Gas ignites instantly but EGT goes up to 770 C so i guess that either the battery is not good or the starter or something is not right.
My money go to the battery.
I will change with a 7 cell 3300 mah GP and see what happens.
Chris