rcdriver22

My Feedback: (1)

OK Guys

Lets talk facts, as this seems like myth buster season, for clarity for those owners of less experience than three months. FOD screens are a very recent addition by most manufacturers. As a guide since the first rc turbines, they have ran 80% of that period without any FOD screens. Were they blowing up regularly during that period. NO[8D]. The smallest object that can hit the turbine wheel must pass down one of the injector sticks. Thats really small diameter and rather basic fact of turbines.

I am a little confused on Dave's post. Firstly I don't know of any commercial or home built design thats uses a a "rear bearing oil nozzle" I cannot imagine a piece of dirt blocking the oil/air flow except at the front. At the rear the oil feed is the shaft tunnel itself, simply as any blockage would need to completely block the area totally between the shaft to the inner wall. Thats not going to happen even if the turbine was buried 3 feet into the earth at 160krpm flying at max.

"These engines are under high stress. And, it doesn't take much for an explosion". Totally disagree with this asertion as exploding turbines are as rare as rocking horse droppings. If they regularly exploded then the AMA, BMFA and IJCM would ban them because no insurer would give cover. Generally when a turbine lets go its usually to an abrupt amd immediate stop (with lots of damage).

Lets talk about bugs then, our turbines are great little 'food blenders' and even greater as a hot oven inside the CC. I've seen wasps bees and flies ingested and nothing happens at all. I would think that putting 150 ants through might not even give a hiccup in turning over at max rpm, except make a nasty mess inside the CC. Provided the area betwen the comp blades and the wedges is free to turn, now put a screw, bolt or a stone as small as pea through and thats going to reek havoc and shreed metal, but explode a turbine thats a very, very rare occurance.

I'll tell a story that a guy was demonstrating his turbine to 120 engineering visitors at a show and as he lent forward his tie got sucked in. The turbine did not explode but came to abrupt dead stop. He looked a rather arkward and trapped until someone cut tie off. He stripped and cleaned that turbine, ran it again the next week.

So grass hopper [:-] over to you

Paul

molo_30

So, hows everyone going with their engines? Would be great to see some more videos of these. Here's a good one:

http://www.youtube.com/watch?v=HiGxk...eature=related

TREADSTONE

cool ......go to 1:18 into this one who said JJ were not good for anything...not me..

http://www.youtube.com/watch?v=JTJRW...eature=related

rorrock

Treadstone, are you trying to say that a brand name turbine would make a better bbq?

LOL

TREADSTONE

... Of course..but you would only be able to afford to BBQ sausages... No Steak...

causeitflies

The starter motor sounds terrible on that one.

rorrock

An only the one sausage at that... perhaps a potato to make some chips...
Mark, perhaps the starter sounds like that because they spilt some bbq sauce on it..
[:-]

molo_30

You guys are seriously in the wrong business. You'd seriously give Jerry Seinfeld a run for his money......

causeitflies

Sounds more like he dropped the bone in it...

MAX NITRO

My Feedback: (1)

I wonder if they know the turbine oil that has liberally coated the shishkebab is highly carcinogenic!

i3dm

My Feedback: (51)

There are a bunch of videos of JJ1400's on my website, in my signature. some flying videos too.

MattyC-130

My Feedback: (5)

I have 2 JJ1400s my latest one I bought used has a 2 piece tail cone. I also have a spare single piece tail cone. Should I change out the 2 piece tail cone and replace it with the single piece tail cone advantages/disadvantages?
Thanks,
Matty

i3dm

My Feedback: (51)

Matty,

the single piece cone runs stronger, and hotter. those are the changes.

fw190pilot

The one piece tailcone will produce more thrust at the expense of a little higher temps (25 50 degrees). Measure the outlet if it is 41 mm don't use it these have been known to cause some rear bearing issues (trap too much heat in the rear bearing).

mowery1

Anyone on here own the JJ 1800?? I'm curious about the spool up time.... I'm also considering another P-80 but the spool up time is sooooo sloooowww... So I'm considering the JJ 1800 as well...Thanks...

MattyC-130

My Feedback: (5)

Changed over to the single piece tail cone. Runs about 30 deg hotter at idle and full throttle, but sounds and looks much better.
HELP!!!!!!!!!!!!!!!!!!!!!
I am on my 3rd starter motor. been going through some used JetJoe ones I acquired. I don't know if they were bad to begin with. I am using a 7.4V 2000MiAmp Lipo pack to power the pump and starter. The first 2 did fine for the first 2 or 3 starts then just died. Yes, the bendix clutch is adjusted properly no binding or spinning after starter disengages. I would like to try a different starter motor, but I have no clue on where and what to get, I would like it to be the same size so it will fit in my bullit starter cone.
Thanks in advance for the help
Matty

knobby1

Hey Mowery1,
The JJ1800 spools up to max from idle in ~3-4 secs, which is pretty much the norm for engines of this thrust range I guess. Much of it is dependent upon EGT's as the FADEC will adjust the accel rate to keep things in check. You can adjust accel and decel rates to a certain extent but you have to be mindfull of overtemps on quick accels and flameouts during quick decels.

The P80's usually spool up fairly well, does it possibly have a problem??

Cheers,
Smithy.

fw190pilot

The starter motor is a 370sd high rpm motor.

MattyC-130

My Feedback: (5)

fw190pilot
Will this one work, looks like the right specs and RPM.
http://www3.towerhobbies.com/cgi-bin...?&I=LXGLK3&P=0

mowery1

I actually sold the p-80 and looking to get a jet joe 1800 possibly.....Just checking to see how they are performing on here before taking the plunge..

fw190pilot

Matty

Should work same size as a jetjoe motor.

vash19

I am thinking of getting a fei boa F16 with a jet joe engine. any help or ideas will be appreciated. please reply with advice on fei boa jets and JJ engine, and what i need to add to get the JJ engine running with no problems. Parts i need to buy or replace to get better performance out of the engine. Thank you

dw_crash

My Feedback: (6)

Matty,

Try a Graupner Speed 300 motor. They work well.

DW_Crash

Brit-In-Taiwan

Hi,

I have spent a couple of days going over the 'many' postings on Jet Joe Turbines.

I was not going to post as at the end of the day, it all comes down to how much you can afford and what you are prepared to put up with.

I do own a Jet Jet 1800 as well as a Jet Cat and PST-1600.

My JJ1800 is a newish one, just over a year old, I work out of Taiwan and was very - very close to going the cheapest route and buying direct from China, but I had done my home work and saw that people were having 'issues' on the turbines brought direct from JJ-China or from the old (2006 etc) overseas dealers.

I decided to go via Mark the Jet Joe U.S dealer, and to be honest I think this is why I do not have any of the issues that I have read. Mark is a first class guy, he set up and tested my turbine before shipping, packaged great and I got it quickly, communication etc was first class, it really was very nearly 'plug and play' with my turbine, just playing with the ECU settings was a head scratcher at times, but the engine has performed beyond what I was expecting to get out of it, yes it is a fraction down on pounds out the back end (just under 17 pounds) but thankfully I do not need full throttle specs to fly my bird.

Is the engine built to the same standards as Jet Cat, nope, sorry but there is a reason why Jet Cats and Wrens are so much more bloody expensive (too much in my humble opinion) but they are built in the states and Europe and have standards and research costs to recover and they really are in many many cases 'plug and play' with first class support and manuals to answer many many of the common questions the 'first timers' need answering quickly.

So as I said at the start, are Jet Joes a total 'non option' - no, that would be silly to say, but you have to go into them with your eyes open, I would only recommend buying one that Gabe or Mark (if buying from the U.S) have set up and ensured is 'working correctly' don't buy from Jet Joe China directly unless you really know about turbines and are prepared to 'tinker' to set up (which come on, is half the fun) - but if you are a 'first time turbiner' then I would recommend you save a little longer and go the Wren / Jet Cat etc route, I know this may loose some first timer jet flyers as the start up cost is much MUCH greater and the fear or slam dunking it on the first flight is maybe too much to handle, but you will be getting in most cases peace of mind the turbine will not be the reason for letting you down on the first flight because you did not know how to set it up correctly, but if you have got some stick time and know your way around a turbine and are not put off by maybe spending a little more time playing around with it, then Jet Joe is a valid 'other' option for those on a lower budget, the same types who enjoy building their own turbines etc.

Remember lads, we are all in this hobby for fun, regardless of what is under the bonnet, getting more 'turbiners' into this hobby is the objective, as it allows firms to build better products at cheaper prices which hopefully will be passed onto 'us' the end user.

Regards,

Gw

SimjetAU

Since having my Schenck HT0B balancer with the CAB720 vector display I have learnt so much more about balancing turbines than I knew before and also dispelled a lot of ideas we used to have and what I still see displayed on these forums I am am not specifically talking about this forum. I used to have Thomas Baumguard's ones which I made 2 of for doing balancing for Simjets that we didnt send back to Simjet for balancing. This worked ok but I knew that we still could not achieve the balance of the factory engine and was never really happy. So I bit the bullet and bought a second hand balancer direct from Schenck that had been gone through and serviced and I also commissioned the local Schenck guy in Sydney to come to Brisbane and calibrate and commission the unit and also give us some training on it. We balanced a rotor assembly as a dumb bell on my original home made balancer to get ready when the Schenck arrived, spent about 8 hrs to get the best balance we could on it then put that rotor in the Schenck as a dumb bell so we didnt take the assembly apart to see just how good the home made balancer was and it turned out that the best sensitivity I could get from it was 20gram/mm on the home made balancer, this was done while the Schenck guy was at the workshop and straight after he had done the calibration run on the Schenck. I can tell you with complete confidence if you pull the engine apart to service it or do any work on bearings etc that even though you think it was balanced previously it is now well out of balance when you put the engine back to gether. We have proved this time and time again. You can NEVER get the compressor back in the same spot. Also lets talk about different types of balancing. The two used for model jet turbines is a "dumb bell balance" or a "core balance" 80% of engines either by commercial manufacturers or home builder are done by the dumb bell balance method. This is fine until you take the compressor off to fit it all back into the engine, you will never get that compressor and nut on the exact positions they were in when you balanced it.

We balance all the engines by the core balance method (we can do dumb bell of course like the one you can get access to). The tailcone and front cover only are removed from the engine and the complete engine is then put into the balancer table on special brackets. The registration mark is placed on the turbine wheel and the engine is spun up with compressed air from the compressor end. We balance at between 4000 or 5000 rpm it doesnt really seem to matter on testing this previously. Once the engine rpm has reached the setting we stipulate the machine takes 2 secs to do the measurement and we get a direct readout of imbalance and angle on both the turbine wheel and compressor at the same time. This makes it really easy to do the balancing each run. My website has many more pics and explanation if you want to look at it.

http://www.kyle.com.au/Balancing/bal..._a_turbine.htm

Now to some actual measurements as requested to back up what I am saying. My offsider has a jetjoe 1200 he did some development work on when they first appeared and it was balanced by my balancer to under 1gram/mm and it was working well for about 3 hrs of running in a model when it spat a fuel needle out of the fuel ring while inflight (a common problem from what we have seen with the engines). He marked the compressor and nut where it was then took the engine apart and replaced the fuel needle and put 2 new bearings in the engine. Reassembled the engine taking extreme care to get it back in the right position put it back in the balancer and hey presto... 40gram/mm out of balance on the compressor and about 35 on the turbine wheel. We have checked this over and over again with different engines just to confirm that you can not get the compressor back in the same place once you pull it apart. This is why we only core balance in stead of dumb bell balance. We can prove this because my balancer shows this as the engine is balanced in the exact running assembly. To my knowledge the only companys using this type of core balancer is myself ( Iam sure the only one in the southern hemisphere), Kerry Sterner in the USA the Simjet factory in Denmark. I think Gbooster in Germany also use a core balancer. I have only had the balancer since September last year but having such a fine piece of test equipment is a joy. The customers so far most all have said they can hear the difference as soon as they start the engine as we not only do Simjet but all makes and models of turbines. There has been comments on this thread about commercial engines and jet joe and homebuilts all flame waring each other about whose is better but I can tell you we have seen many other commercial engines from the factory certainly not having perfect balancing done. I can also tell you we just recently did a 1400 and a 1800 engine that we balanced that was balanced in the factory and they were over 90gram/mm out at the turbine end and around 50 gram/mm at the compressor end...of course they are now under 1 gram/mm .

Regards

Mark Kyle
Kyle Communications
Simjet Australia