How did you reduce the compressor clearance, did you just shim it forward.

See your club has the same indent as ours lmfc.

Machined the front cover till it just touched. Then used fine wet and dry where it scraped the marker pen I put on it on my olde lathe.. I used to build these things. Keep repeating untill as much of the front cover and compressor is almost touching as possible. Then give it one more go, thats the running clearance

The biggest difference between a wren mw54 and a supersport is the running clearance and its also why they dont sell it as a self assembly kit.

If it helps the supersport it will help the JJ too. There was loads of clearance on mine, and once set up a bit tighter it runs cooler and better especially at startup. But I dont know about thrust because I didnt measure that before... But if the compressor is less "leaky" then it becomes more efficient.

What glow plug is the JJ-1400 normally supplied with at purchase here in the U.S. ?

I'd like to keep the voltage setting the same when changing plugs, and not have to readjust it.

Thanks.

Ed

The JetJoe comes with a OS A3 plug.

the egv is red glow

I agree on the running clearances, also you might later try a 14 blade compressor ($50) and increacing the see through on the NGV. The burn in the picture looks rather red than the usual nice cool blue. Not sure what Sara will make of you using Wren parts to upgrade a JJ1400, you may not get any cakes if you visit them.

The red is because its accelerating and its almost dark. The camera makes it look like its glowing hot though! You dont see it in normal daylight? EGT is about 650 at full power. I already have a 14 blade compressor (I think?).

I have lots of bits laying about. Including a kamps and an old Shreckling built ten years ago and jj bits etc.

Early JJ motors were sort of good home built motors that needed some fine tuning and setting up.

As for upgrading with wren bits, why not? I had them! They fit, and they help. Its all just bits of metal at the end of the day. The tailpipe was swapped because the JJ one was too tight and hard to remove after a run or two. And because it ran a bit hot with the single bit jj one and the wren one was bigger area outlet after I cut 3mm off it for yet another home built mw54. The FOD screen front end was because I watched a huge bee go in at about 1/3rd power in my garden... Motor never even coughed though.

Because the engine looks like a Wren, but isn't. There's already been one incident with a JJ being sold as a Wren by disguising it with our FOD screen and tailcone. The new purchaser only got a couple of flights before the engine failed catastrophically, spitting turbine blades out. Everyone at that flying field thought it was a Wren ...

We've worked hard to make good engines, we have an excellent reputation and when we see an engine which looks like a Wren but is a cheap Chinese copy, we get angry. I think any other manufacturer would feel the same.

Sara Parish
Wren Turbines

You have no need to worry as I have no intention of selling it ever and certainly not as a wren!
I make it quite clear that its a mix of bits to everyone.
As I said earlier I treat JJ motors as a good homebuilt that needs the same care, caution and setting up. I know the turbine wheel wasnt certified, neither was the one in my old Shreckling. I keep very clear!

I can understand why you would get upset though as I saw the other thread you pm me a link to.


People do this though with everything to do this hobby, and others. EG my car is a ford with a V8 Rover engine.
My helis are a mix of all kinds of bits.
My DF motor is OS but has piston and liner from an OPS modded to fit.
My canon camera has an adapter that lets me use Nikon lenses. (Actually it doesent I use Nikon but I was reading about this adapter a guy made two mins ago and its the same thing)

But you see the point. People will do it.
Most people think all turbines look the same. Those that know will see most likely that its not a wren because of the engine casing or in any case becase I tell them.

I understand your fears but I treat it as a home built so its safe. Even I am scared of something letting go! But you cant really stop people swapping or adapting parts for everything in this hobby as its part of the fun.

I agree. We swap parts all the time. OS carbs on ST-3000. TT parts in an OS engine. It is part of the hobby. At heart, most modellers are fiddler. We repair and try to improve. So, a few WREN parts in a JJ was bound to happen. AND, Sara should be happy that, in her view, higher quality parts are replacing lower quality. Wouldn't that make it safer?

DW_Crash

It's like putting a Corvette Bumper on a Pinto.....

Sure it looks better, but it's still going to blow up. I wouldn't know any manufacture that would be happy at that point.

Works in reverse too, a guy I know bought a S/H manual start wren 54, and upgraded it with a new JetJoe front cover and bullet starter as it was less than half the price of the wren one. Hope he dos'nt sell it as a JetJoe

I received my new JJ1400 turbine today. It looks good. It is going on my Falcon 120. Notice the tailcone. It also has a FOD screen installed.

The new JetJoe 3000 is on the JetJoe website now.

Yes Mark, I noticed that Jet-Joe was advertising the 3000 on his website a couple of days ago, I can find no price for it though? I haven't finished my testing, evaluation and modification of the one I have as yet either!! I hope he hasn't "jumped the gun" somewhat. So far it looks to be quite a robust engine, considering some of the early JJ engines were a little "fragile" to say the least.

The factory balance job done to the particular "pre-production" engine I have, (it doesn't sport a serial number!?) was actually very good, I did a "core check balance" on it just last week and was quite surprised to see numbers in the very low "teens" on the mg-in scale on my Schenck CAB960H machine, very encouraging indeed and much needed on the 70mm turbine wheel, I only needed to give it a small touch-up to bring it into single figures, bare in mind however that numbers below ~28mg-in will give a very nice result, we're talking 0.001 of an oz-in on the grind radius that we're using, very small numbers indeed. I consider the balance of the rotatives to be one of the most critical items on our model turbine engines.

Jet-Joe (Jeff) himself has asked me to make any modifications I deem necessary to make the engine run nicely and to be honest, I can see maybe just two or three items which need attention and I have already given Jeff my thoughts as to my findings, just some minor things which I believe will help make the engine perform a little more reliably.

One thing which I would like to see is a later model FADEC/ECU unit, the one supplied is the Nades AU-540, although it works well, is a little dated and I believe ceased production nearly 4 years ago! The supplied fuel pump is the nice FlightWorks 400-B unit and suits the engine nicely.

I've done a few test runs up to full noise so far, (115k) and I can tell everybody that this engine does indeed make the claimed 30lbs of static thrust, in fact I measured three clear runs of well over 31lbs with EGT's in the 620-630c range, not bad at all. The acceleration rate has been the sticking point and originally the engine would not run up as nicely as one would like, bare in mind though that ten years ago it would have been classed as a rocket!!.... but after some "modifications" to the combustion chamber and other little "secretive" items and some tweaking of the ECU I have been able get a very respectable 3.2 seconds from idle to max rpm, not bad at all.

The sound of this engine is quite unlike any that I have heard to date, I guess it most resembles the Jet-Central Rhino but is still "different" and has a noise all it's own, for those who love turbine engines....its a beautiful noise!! I have measured the fuel consumption at ~465ml/min and although it is just slightly higher than the quoted figure on the JJ website (16oz/min~455ml/min) I can't really fault it.

I will post further updates as I progress, but at this point, although nowhere near the Wren, Jet-Cat or Jet Central for quality... the JJ-3000 looks to be a reasonably good engine.

Cheers,
Smithy.

Are your tweaks being sent back to JetJoe for improving the production run?

DW_Crash

Glad to see JetJoe are moving forward, if nothing else to keep winding up the people who knock them

Yes DW,
Jeff and I converse regularly, so I really hope he's listening to us, he's very interested in getting this engine to a good reliable setup, time will tell.
So far, so good, I've given this one a pretty hard time and it is standing up to it thus far.
I had it running at 90%+(up near 100k) for over 30 mins on the weekend, (I'm sure my nearby neighbors are happy about that!) and all seems good, I was trying to see if the aluminum housing would distort or if I could make something let go, but it just didn't happen!! Used a helluva lot of fuel doing it too

Cheers,
Smithy.

Hey Xair,
Don't get me wrong, I'm not for one minute suggesting this is a high quality engine, the likes of Wren, Jet-Cat, AMT and Jet-Central would put it to shame, I would however suggest it may be a cheaper alternative to one of the engines listed. There are so many good engines out now it makes the mind boggle!

Cheers,
Smithy.

So true Smithy. There are many good engines out there. I'd figure none are bad, just some better. And, you get what you pay for.

DW_Crash

Smithy:

Was this after you performed your balanced?

Hello Guys

I dont know if its good. I think it is, but its nice.

Bought FOUR JJ1400 to date £3000+
from Joe and I have kept none of them

After running all of them long and extensively, as a GTBA member, only buy from a known rep who understands swarf/tollerances in the lbuild i.e Andy in the UK.

It is worth the $300 £400 extra to have one at least JJ flying in the air. (that's not just one sat in a work bench or land based in a RC car)

Resale or Residual value on a JJ!?? buy for a dollar, sold for a cent. Who wants them 2nd now ?

Actually both, I did some testing both before and after, no noticeable difference between each to be honest.

Cheers,
Smithy.

I have not seen a used JJ for sale since I started looking for a turbine. But if anybody wants to sell one for a cent on the dollar I will be happy to take it of there hands.