RE: JetJoe OWNERS thread
 

Hi Leighton,

I am not sure how comparable the JJJr is to the JetCat P20. Presumably the JetCat is far superior in quality and overall, and a little more thrust at 20N (approx. 4.5lb). I have heard that the JetCat is a great little turbine. I come into the Jet Joe fraternity without expectations, as I have heard both positive and negatives for JJ. i know a little of the history of the one I bought, as apparently it had bearing failure after only a few runs. it has been totally rebuilt by Brett Smith, the Aussie Jet Joe service guy, who apparently makes these things run like little gems. It has not run since the rebuild, apart from testing by Brett, so I am optimistic that it will run well. it will be interesting to see what "real" thrust this little engine can produce.

James.

RE: JetJoe OWNERS thread
 

It may have been posted here already, and probably in another forum somewhere, but what effect does modifying the exhaust cone have on thrust and exhaust temp? Does a thrust tube help with achieving any more thrust?

RE: JetJoe OWNERS thread
 

ALso, I wonder if any of the Kolibri parts will fit the JJJr? For example, the inner exhaust cone, or the electric starter?

RE: JetJoe OWNERS thread
 

Hi,

Assuming your motor is fresh and known to be in good shape you will want to run the motor and note the temp along the thrust curve. You want the temp at full bore in the low to mid 600's max. I have been told that the motors put out the best power at ~ 720 or so but your NGV is not going to last if you run at that high temp. Carefully mill down or cut the cone in small increments until the temps are acceptable. Also make sure to run a dremel along the inside of the cone each time you cut as any burrs can affect the temps as well. You can converge your exhaust tube but your temps start to go up again. Widening the cone lowers thrust.Converged pipe (big to small at opening) raises thrust but also raises temps. Be carfeful when you play with this and watch your temps.My feeling is that it is better to sacrifice some power and have a healthier running motor that will last longer. I am sure most will agree that over temp is your worst enemy on these motors.

Andy

RE: JetJoe OWNERS thread
 

The starter is ~ 24.2 mm ...Speed 300 motor works. not sure what the Kolibri takes. Are you talking about the exhaust cone on the motor or exhaust pipe?

RE: JetJoe OWNERS thread
 

Hi Andy, thanks for you comments, they are much appreciated. I am brand new to turbines, so you will have to excuse my ignorance. I presume NGV is nozzle guide vanes?

When I referred to the inner exhaust cone, i meant this bit:


But I think it is an old design.

RE: JetJoe OWNERS thread
 

Hi,

Yes NGV Nozzle Guide Vanes. You are going to find some differing opinions butwhen it comes to heat, I think everyone will agree that high heatdoes a real number on theseengines. The photo does not look like anything off JetJoe 1400 or other motors.

In any event, Ido not thinkyou will needtheinner exhaust cone in your photo.

Andy

RE: JetJoe OWNERS thread
 

Hi Andy,

The photo is a Kolibri. They used to have the little cone in the centre, but may not nowadays. It is interesting you mention the EGT, as the JJJr manual claims an EGT of around 800ºC at full rpm is normal. They definitely seem to run hotter than their larger cousins, presumably because of the much greater rpm (235,000).

Has anyone managed to successfully add an autostart motor system to the Junior?

James.

RE: JetJoe OWNERS thread
 

James,

Iguess each motor has its caveats. I don't know the Kolibri nor the junior.I would think that an auto start system ought to work on any motor as long as the ECU is setup for it.

Andy

RE: JetJoe OWNERS thread
 

Hello all. I am looking to buy a blown up jet joe. Anyone got one laying around? I also need the ecu, sensors.. ect.... I have a garage project and need some parts. Not too critical on what size/model.

Thanks,

Robert

RE: JetJoe OWNERS thread
 

[link=http://www.rcuniverse.com/forum/m_10896430/tm.htm]JetJoe JJ-1800 Kerostart[/link]...

RE: JetJoe OWNERS thread
 

Hello everyone I am a newbie to this forum. I recently purcased a used but pretty new jj3000. A friend and I tried to run and determined it had a bad tcouple. We removed his from a wren and it ran fine. My question is the 3000 really realy loud? It seams a lot louder than others in its class. We dialed the exhaust gas temp back too 600c was set for 780 seemed real high. Any thoughts on the would help. May just be the way it is. Kids said it shook the house with it in the drivewaY. Thanks Blake K

RE: JetJoe OWNERS thread
 

They are loud yes.

800 is standard temp limit. Don't use 600. This value does not control the engine, it triggers a shutdown if the value you enter is exceeded. My engines run 620 - 650 normally. 800 is what should be in there. 780 is fine as I would not want to be running the thing consistently at 780 or above either.It is only an absolute limit.

Andy

RE: JetJoe OWNERS thread
 

Thanks for the insight. When it ran it hovered around 596 so it could go higher. I make the max 780 again and run it there making sure it stays in the 620 to 650 range. I did not realize that waS a shutdowm max temp. One more thing would a slight out of roundness to the nozzle make it louder? Thanks again. Blalke K

RE: JetJoe OWNERS thread
 

Blake,

yes this is a max temp... you never want to exceed. 596 is nice and cool. I would not worry about this temp one stitch

Andy

RE: JetJoe OWNERS thread
 

Hi all,

I helped Blake run that JJ-3000, and the Max temp on the ECU was set at 890 c !!! I put it down to 780c before the first run. But yes... it runs cool. I think we saw 730c as it was starting, but when it got to idle... it was right around 600.

The engine seems to run fine up to 85~90% power. But, at full power... the nozzle starts to glow. Is it normal for the 3000 to glow at full noise?

RE: JetJoe OWNERS thread
 

If that thing is spinning full RPM and there is a red glo at dusk or minimal lighting, this is normal.Temps at 600 and change are low.Your motor will produceoptimal thrustat 700 or so but lower temps help preserve the motor.The 3000 puts out some decent thrust so keep the low temps.The only thing that will change the temps here is the nozzle opening, meaninga lot of people have to mill down the exhaust cone to provide more flow and lowertemps when temps are too high. If the motor ever reached 890, you'd probably start seeing pieces of metal coming out of the motor as the NGVstarts to breakdown but Ihave never tested that theory.

600 is nice.

Andy

RE: JetJoe OWNERS thread
 

Depends on the light level tony they all glow when started at night/late evening, so long as the egt probe is working and calibrated correctly it is not an issue unless it is running at 750c +. Thinner material used for the exhaust cone will obviously glow easier than a thicker cone.

The single cone tailpipes are noisy, I changed a twin cone on a wren 54 to a single cone and it was a lot louder, big difference noticed when you shut it down, it would let out a roar where as the other cone it was just a whoosh!

RE: JetJoe OWNERS thread
 

Hi James
Here you have a JJR with Autostart
On youtube 20111224125856.M2TS
And here you can read more
http://www.rcmodelistas.es/foro/avio...t2908-100.html

Jean

RE: JetJoe OWNERS thread
 

Thanks Jean. Yes, I have seen the rcmodelistas.es thread already. It is very helpful. I will check out the video too. Thanks again.

Actually, since I first ran my Junior at Smithy's place, I have not been able to get it running again after setting it up at home. I have gone over every step time and time again, but I just can't get it to run past about 45K rpm. It just ends up going over temp (>800ºC) and will not continue to ramp up to idle. I suspect that there is a problem with the fuel pump at low voltage, but we did use the same pump when we ran it the first time. I am now planning on taking it back over to Smithy's place to try to sort it out.

James.

RE: JetJoe OWNERS thread
 

On the jjr I opened the tail cone to 25mm. it is thin you can use a deepwell socket and work the cone to look like the picture. opening from 24.25 to 25mm dropped temp from 790 to 760 PW dropped 21 point 443t o 422. easier to start with larger opening and revs a bit qucker. trick to start a small turbine is to get gas to burn in the chamber not the tail pipe.I have a video on my phone starting a few weeks ago.

RE: JetJoe OWNERS thread
 

http://www.youtube.com/my_videos_tim...id=0Kz34qDvMTQ

RE: JetJoe OWNERS thread
 

Thanks idleup. Maybe I am not getting combustion in the chamber, I guess that could be an issue.

P.S. your video link does not work, can you please check the link and send again? thanks.

RE: JetJoe OWNERS thread
 

should work now. its hard to air start and work a camera phone at the same time.

RE: JetJoe OWNERS thread
 

Thanks idleup, but still does not work. Is this the link you were trying to send: [link=http://www.youtube.com/watch?v=0Kz34qDvMTQ]http://www.youtube.com/watch?v=0Kz34qDvMTQ[/link]