ORIGINAL: knobby1
ORIGINAL: BJ64
It's probably been quoted somewhere amongst the many pages in the JJ threads, but what would be the max EGT for a JJ-3000 as I haven't seen anything but a single tailcone for these things?
BJ
Hey BJ,
The 3000 was/is still a two piece exhaust, it has an inner cone although the outer is similar in design to the smaller 1200/1400 single piece setups. BJ, you'll notice yours have an inner cone. The 3000's are a comparatively cool running engine, most of the ones I've seen will run ~570-600 at full noise and will spike to just on 700 during start, this is fairly normal and nothing to worry about. A nice cherry glow on the pipe is telling you the temps are in the ''zone''. If the colour turns to a brighter orange or red, it's time to do something about it. A ''transitional'' change in colour is normal during acceleration and should return to a dull cherry red when the rpms have stabilized.
The 3000's.... strangely for a Jet-Joe do actually make 30lbs of thrust, the ATJ-120Ti which is also a 30lb turbine will run a comparatively higher EGT and consistantly records well in excess of 31lbs and in some cases up to 33lbs on nice dense air.
If the start temp does climb too high, just adjust the ''starter power during ramp'' parameter and she'll drop the EGT accordingly, or alternately drop the gas a little. It's better to have a quick warm-ish start than a prolonged hot one. Each engine will react slightly differently to the parameters so adjust them to suit your individual engine, that's what they have adjustments for.
Cheers,
Smithy.
Thanks Brett
As always, your info is timely and helpful.
From memory, I usually see 800+ during the start process. I'll make a log of my temps for both my Turbines during the next spool-up and maybe we could work out which Parms might need a bit of tweaking?
I've also noticed that my 'fuel ramp' phase seems to take a fair while, although I can shut the Propane off fairly early on in the piece. i.e. I can turn the gas off at the bottle pretty much as soon as I hear the revs build and see the fuel moving in the fuel line, but it takes a while before I see 'Running' on the Monitor. I'll see if I can get some decent timings for each phase so that I have some 'accurate' stats for this.
BJ
PS - the JJ-3000 runs a 'two-piece' cone? I only notice one 'cone' piece coming out of the rear. Am I missing something here?