knobby1

Hey All,
I've finally got off my fat arse and uploaded the video to Youtube of my JJ1800's first test run with afterburner, hope you enjoy, i'll hopefully have a more indepth video coming soon which explains all the "gubbins" attached to my setup etc... You'll notice I'm continually looking at and monitoring the EGT, maybe I'm just paranoid[X(]

From what I understand it may be the very first JetJoe engine which has been fitted with an afterburner, as usual, I stand corrected though

http://www.youtube.com/watch?v=0e_lJJCG5WM

Cheers,
Smithy.

josecilurzo

Hi guys,

somebody knows the electronic balancer of the JETJOE? it is good?

JOSE

knobby1

Hi Jose,
The JetJoe electronic balancer is fine for the home miniature turbine builder, however, for serious service work and commercial balancing I feel it's accuracy isn't up to the standard required.

Don't get me wrong, the JJ balancer works fine, I find I can get down to very small dual plane increments with the "Schenck" machine I have access to..... whereas the JetJoe balancer has only a single plane system. Here's a pic or two of my Schenck machine.





Hope this helps,

Cheers,
Smithy.

josecilurzo

my problem is that the shipment cost is very high ( US$450,00 ), necessary to make the maintenance here in the Brazil, in this case, its necessary to have a balancer.
I believe to be necessary to balance the engine always that to disassemble. Its correct?
This balancer is fine to do that?

thank's for your help

jose

knobby1

Hi Jose,
Yes, the JJ balancer will be fine for what you wish to use it for, and yes, I believe the rotor assembly should be balanced every time it is dis-assembled. Be sure to check it two or three times to get an average and for consistancy, sometimes even large changes in temperature can affect the balance readings depending on the machine used.

I find our balance machine shows minor variations when a heavy truck passes by the workshop...!! Crazy but true!

Cheers,
Smithy.

Strykaas

Nice video. Those short plumes are a little astonishing. What's causing them ? Residual fuel is burnt after "injection" ?
Do you think that sustained operation ( # 10 sec ) is feasible ?
I'm no AB expert but the flame shape at low RPMs makes me think injection is sub-optimal at this point. Compared to real size turbine engines, flame shape is radically different. HIgher RPMs produce a better looking flame shape. I think there's still some optimizing margin in that area.

knobby1

Hey Strykaas,

What you say is exactly correct, I expect it is "residual fuel" in the lines and spray ring. There is still a lot of development work to do, this was one of the very first test runs so I expected some shortcomings. The low rpm stuff which is what you mostly see on the video shows a less than optimal combustion, Jet dragsters predominantly use this as a "fire show".... as higher rpms are approached the shape and burn of the fuel is much better, more of a shortish blue coloured flame rather than a messy orange one, it's rather hard to see the "good" flame in the bright sunlight though, however, the ignition of the fuel at higher rpms is also less than optimal and is still a bit erratic. I believe a burst of 10secs or so isn't out of the question, mind you the amount of fuel consumed is enormous, so you'd need to carry quite a good supply...that little 3 min run on the video consumed just under a liter of fuel through the A/B...[X(] plus what the engine itself used.

I still have to sort the fuel burn quantaties as well so more work is needed in that area, I expect in a month or two, some tinkering and fine tuning she should be making all the right noises, then i'll post a decent video of it running at it's best, I should do a night time run too, that'll be interesting to say the least!

Cheers,
Smithy.

Strykaas

Nice [8D]. Did you estimate your TSFC ? The sweet spot should be around 1.5 according to http://www.grc.nasa.gov/WWW/K-12/airplane/sfc.html and around 2.00 according to http://www.udel.edu/inst/jan2000/sti...ISE/sld003.htm ...
I guess it is much more than that ...
That night run is a great idea for sure [:-]

josecilurzo

Thank's Brett for your help,

best regards
jose [8D]

monkeyking

Hey All!!!
For those who say that the JJ doesn´t work...here you have a fly by of my Stingray jet with a JJ 1400... more than 200 mph

http://www.youtube.com/watch?v=albhttQvpBs

topgun42usa

My Feedback: (142)

Cool flyby ..like to see some take offs and landing too..lol...have fun....

monkeyking

Hey!
I bought my first plane one year ago and my jet 2 weeks ago to a friend of mine :S...and that was the second time that I fly my jet...the takes off were fine, but you can imagine the landings...
I will practice some landings tomorrow...I will publish more videos and send the links!
Hope to back home with the jet complete to practice the sunday too...lol....

Have fun!
Mauro.-

josecilurzo

levelling beauty!!!!!!!!!!! money king.

jose[8D]

Props4ever

Hi Guys

I have been following this thread for sometime and now I want to know if I could buy JJs in Canada?, Plus I also like to know lbs of thrust per turbine model JJ offers and cost of them. Website dosent fully show everything.

KC36330

JetJoe USA seams pretty simple on the specifications side of the page telling thrust of each turbine, as well as the price of the turbine and different options.

from the webpage, click on the engine of choice for different options:

Thrust of the 1800:



Price:

monkeyking

Hi to All...
Here I am again...with more problems :S
After a few flies yesterday I noticed one side of the cone (the one that has the thermocouple) warmer than the other parts of the cone....the turbine had problems to acelerate because it was very warmed and the pump didnt pump...I had to take the thermocouple practically out to get 680°C...so I decided to disassemble it...
I found that the NGV was over heated with some parts deformed as you can see in the pictures.
I revised the CC but I didnt find nothing extrange...the CC is new. I tested the ring with gas and all the injectors it seems to has the same caudal.

What do you think about that? Wich could be the problem?
Hope you can help me!!!

Thanks!
M.-

fw190pilot

Looks like the ngv may have a crack in it your dealer should be able to fix it.

KC36330

looks to me like you allowed fuel to accumulate in the CC and burn with the turbine not spinning or the result of a hot start (or post crash) that wasn't extinguished in a timely fashion.

monkeyking

Hi!
Thanks for your response!

KC36330..
The turbine runs everytime over heated in that side of the cone...this problem is not only in the start procedure

fw190pilot..
I thought that...I believe that it could be a factiry problem in the NGV


OTH...the NGV doesnt fit ok in the CC because the deformation...I think that if the NGV was wrong from the factory maybe it can be passing the hot gas/fuel between the CC and the NGV and this cause the problem

What do you think?

Thanks again!
M.-

Gerald Rutten

Hi M,

I think more the other way around, pressure outside chamber is higher than the inside so air will only enter the CC. Still if the CC backring doesn't fit correctly it will give a hotspot over there due to uneven air distribution. I had the same on one of my KJ's where the CC outer wrapper had become slightly distorted over time where the fit to the CC rear wall outer was bad. An air gap of 0.8mm on a 1/3 circumference on the bottom of the CC made the hotspot you see on the picture. When I simply "hammered" the plating to close the gap again the hotspot was totally gone, see picture withoud the red glow. This is a homebuilt engine so I can do what I like, for your engine I would however try to make the company fix it......

Rgds,
Gerald

monkeyking

Hi Gerald!
Thanks for your response!

I measured the CC and the NGV..there is a difference of 0.8 milimeters in the diameter in some parts...so if the CC is not centered correctly I can have the 0.8 mm in one side :S:S:S:S
I measured the two CC, both has the same difference..I think it is too much gap, what do you think??

Thanks!

rcguy!

My Feedback: (69)

Is this the same JJ1400 shown in post 1493? Can you say how many hours you have on it?

Dave

monkeyking

Hi
Yes, that is one of the turbines..That one works, but the temp was a little bit high..about 720°C at full throttle...so I decided to disassembled it.. the NGV was deformed due to the high temp in one side
Both turbines has the CC and bearings new.
The NGV of one of them was new.

Thanks,
Mauro.-

rcdriver22

My Feedback: (1)

Hi Mauro

The deformation might tend to indicate prolonged running at high temps over a much longer timescale. Reviewing the 50+ minutes of running data held in the ECU might give an indication. Have you considerd swopping the NGV over from the one thats not working? When temps start to progessively rise from 620-650 normal operation temps its a clear indicator that something is amiss inside. If the temp probe is not inside this hot spot area, then the real temps are very much higher. I am assuming there is no warranty from the JJ Chilean rep on these two turbines.

Paul

Joe Bladwin

This is called "tolerance", or better, "the lack of accuracy" that you often read in this thread. The parts made with close tolerances are much more expensive that the "loose" parts that your engine has, and this has caused the hot run and the destruction of the EGV. If you measure the diameter of the inner tube of the CC you will also find an loose adjustment to the EGV. You just have found the main cause of the difference of the price with wren or other reliable engine.

I doubt that the "afterburner" in previous page provide any significant and measurable increment of thrust. The "claimed" 30lb are absolutely a invention of the current dealer in Oz.