Oscar

This one is pretty famous - from a NACA / NASA test:

 

http://hmf.enseeiht.fr/travaux/bei/beiep/sites/default/files/users/lclavell/wakevortex_large_9-14-072.jpg

 

 

Different piston skirt design, or maybe oil jets. It is very likely the piston crown runs too hot. We run CHT gauges but have no idea about piston temps, which is the other half of the combustion space. They way some look they are obviously HOT. Nev

CAMit is very aware of the piston crown heat problem / situation and I'm sure they have it 'on their list'. As with everything else they've done, we won't be told what they have found to be the answer until it's been tested thoroughly and found to be a) of positive benefit, and b) reliable and effective in real flying conditions.

 

 

Not really. There are a lot of 912s flying round with zero carb heat and/or electric/coolant heated jackets on the manifold downstream of the butterfly. The aim being not to heat the air but just to melt ice off the manifold wall which of course needs far fewer kW and does not significantly change the air inlet temperature.

Let's just hang on a moment here. Physics doesn't change with engine manufacturer. I don't care what is sucking on the carby, if the airflow pressure differential through the carby throat and ambient temp and humidity is the same, ice will form, no matter what label is on the engine. Ice typically does NOT form on the manifold wall, FFS. It may be that the dual carbys on 912's do not have the pressure gradient situation of the single carby on a Jab, but in the right (er, perhaps that should be the WRONG) situation they will have IDENTICAL icing problems if the combination of airflow through the carby (ies), temperature and humidity occur.

 

 

Ian said that the optimum time for a squirt was after switching off the mags and before the prop stopped ! Good Luck! But quite a good idea anyway............

Aha - thanks for that info, I wasn't sure if the question had been resolved.. The timing sounds a bit tricky, but the CAMit engines are reportedly somewhat freer on shut-down than the normal Jab. engine (can be easily turned over by hand rather than really tight - but JabSP6 is the one who can advise us all there!) so it may not be quite as difficult to get the squirt in as one might think.

 

 

I wasn't there but I think its the pre shutdown oiling system designed to prevent barrel corrosion between runs. The red lines are the oil injection lines that go to each head to inject into the inlet valve plenum for each cylinder.Available soon as a bolt on to existing engines

 

Andy

Andy - yep, that's the inhibitor squirter set-up, but they actually inject into the inlet port just ahead of the inlet valve so the (warm engine) oil hits the warm valve face and gets sprayed around the barrel. I believe CAMit are still testing to determine the optimum time for injecting the inhibitor oil so it is done at the best time for dispersing the oil and not having it all just run off the sides of the barrel and that may be some minutes after initial shut-down. The injectors themselves are very slim tubes of almost surgical-implement quality, when installing them one feels that one should be wearing a gown and mask and calling for the theatre nurse to hand them over..

 

 

I wonder of anybody has ever looked at the CHTs on a Jab with the front wheel spat vs no spat.

 

 

Well, that's unfortunate and no doubt an annoyance for those who would have liked to be able to talk to Ian more usefully. However, it seems to be somewhat of the norm for any gathering of people discussing Jabirus, and quite often, coming from someone who does not actually OWN a Jab. engine but is regurgitating stuff he's heard from 'mates', or on forums etc. as if it's gospel.

 

My co-owner did attend, and deliberately went around talking to as many Jab. owners as he could find, and the general reaction he got was one of 'no significant worries' - including several who were somewhat bemused at the strength of discussion on cooling. Just about all of these had full cht/egt monitoring set-up, and just perhaps it is the fact that they take the trouble to find out what's happening in their engine that they seem to be those with few problems! One Jab. 3300 engined Sonex owner reported that he was entirely happy with his temps, using the standard Jab. cooling inlet set-up, and didn't see what all the fuss was about.

 

 

They had a stand at NATFLY the engine on display was a very neat & well built engine. Couple of noticeable changes they run a alternator, the base of the barrels are thicker. The was always a crowd at the stand every day I was there & the chap that ran the stand was well informed with his product & even being bombarded by one blokes smart **** questions. My personal opinion I think its a lot stronger engine than the one Jabiru is selling. But the only way to prove it is flight time to see how it will hold.

Interesting; was the 'smart' person actually asking questions or just in the main telling Ian what his (the person's) opinion was? Questions are good when genuine information is being sought; pretty useless waste of time when they are just a way of forcing one's opinion down everybody's throat. There's plenty of the latter goes on with Jabiru engines..

 

 

No, I've always been called in to sort out the mess.

That's not entirely true - your own aircraft design is sitting in your hangar and being worked on when there's a gap in the necessity to help resolve other people's messes. The old adage that 'the cobbler's children have no shoes' applies.

 

 

David, I agree with all that you have said - but the result has been that we are the easiest group to be sacrificed. That is the situation that we need to address.

 

 

Well if you shut it down you remove all risk and don't have to shoulder any responsibility. So if you want to fly in to the festival tough, they will lose a very small amount of attendance and have again marginalized a select group of the community. There is no reason why it could not be kept operating if the splays are in place. If you want to remove all risk then close the bloody streets as well FFS.Rant rant rant rant ......

 

can you tell i am not impressed, they are so conservative now they might as well be CASA, but even CASA would let the field operate if the splays were in place.

My bolding.

 

However - if this result doesn't tell us just how precariously we are perched on the edge of community acceptability, then we are deluding ourselves. It's no great jump from being excluded for a particular event to being excluded from an area entirely by the removal of an airfield because the bloody local Council can get a bucket-load of rates from selling the land. It's no use feeling umbraged, what is needed is positive action to make 'Recreational Aviation' a desired part of local community living. Unless the local community values our presence, we cannot expect their support.

 

 

Well - an early report from Natfly says the CAMit stand is 'take a ticket' stuff at the moment! I hope we'll get some posts here from people who have made the pilgrimage and viewed the Mona Lisa(s) letting us know what they think. It's easy to be enthusiastic when you have seen the stuff at the factory, but the real test is people bouncing their experiences off Ian Bent and being able to evaluate what work has been done (and why) to fixing the problems they have had. There is nothing better than the exchange of information in a situation where both sides can dig down through the problems and look at them in decent depth, and I have no doubt that Ian Bent will be listening very hard to what people have to tell him.

 

I'm prepared to bet that Ian will return to CAMit with more ideas for improvements, because he is by nature the sort of person who listens to what people tell him. This can only be good for the future of we Jab./Jab-based engined aircraft owners.

 

 

Yes I have an MGL mini Efis fitted. I have done extensive work modifying the air inlets and outlets on the engine cowls as well as the oil cooler ducting. The highest CHT's I have seen is in climb out during summer. 145 degrees. Normal cruise temp are between 110 in winter and 125 in summer. I have all 6 temps within about 10 degrees. The egt's still have about 40 degrees spread in cruise which I have not done too much about yet.In all I am very happy with Camit's engine and I am looking forward to doing many more hours flying without having any issues. I will keep everyone informed.

Safe flying

 

Andrew

Very, very encouraging temps there. The work you have done on the cooling airflow is obviously working well and hopefully with information being exchanged amongst owners we will assemble a good picture of what works and what doesn't, and perhaps CAMit can be encouraged and assisted to compile some sort of 'here's a compendium of mods that you might try' guide for people who install their engines.

 

Incidentally, how do you find the MGL? We're planning to use an 'Xtreme' EMS and any advice would be welcomed.

 

 

Andrew - great to have the continuing feedback. Do you have chts and egt's on all pots? - it'd be useful to hear what temps you are getting!

 

 

You really are a ponce.

 

 

I fail to see what that has to do with what I said. We will soon be a 3rd world country because we are over regulated and have changed the rules so to speak, to make dead horses competitive. In regard to this question, if I'm a paying customer, the rules are different than if I was a willing passenger in a rec aircraft.

No, that's just not good enough.

 

We have standards - at varying levels - for 'recreational aviation' aircraft. 24-reg and 55-reg. aircraft have specific standards that exceed 19-reg., for instance. If I as an 'informed' passenger choose to step into a 19-reg aircraft, I do so in the knowledge that my judgement of the capability of the builder and maintainer is ultimately my responsibility. However, if I step into a 24 or 55-reg aircraft, I have a 'reasonable' expectation that that aircraft meets a higher standard. That is what the bloody standards exist to provide - an expectable level of safety. If the PIC has an RAA Certificate, an RPL or a PPL, I have a 'reasonable' expectation of a specific level of competence. I don't have the right to expect GA or RPT safety standards, but neither am I de facto 'abandoning all hope' if I choose to step into a 24 or 55-reg RAA aircraft.

 

The precedent of recreational aviation being an 'inherently dangerous activity' as a blanket legal description of participation in any level of RAA aviation fundamentally destroys the enforcement of standards and the defence of operation in accordance with standards. The charge of - or defence against - negligence is in practical terms defined by non-observance of or adherence to, accepted standards. No Court would, for example, find a defendant guilty of negligence for failing to warn a Pilates class about the possibility of Hippopotamus attack in Iceland - unless there was a specific standard that required such a warning. If there WERE - and an Icelandic Pilates class participant were injured in a Hippopotamus attack - then negligence is a reasonable judgement.

 

We all make assumptions about things every day that can injure us and we all expect that if these assumptions are legally 'reasonable', there should be some protection from the negligent action of others. To say that that is reducing us to a 'third world country' status is just complete bollocks.

 

 

Most of it has drip-fed anyway, but a concatenated version is not going to be good news for the RAA (issued a pilots certificate to someone who claimed - and who signed??) - training at a FTF that didn't exist, and in the light of some of the very dodgy stuff that has been shown in pictures in the preliminary ATSB report, if the manufacturer signed off this one as a 'factory build' ( I stress that I don't know about that, but it was 24-reg.; following the CASA audit many Morgans were dropped to 19-reg) then I'd reckon there's a side-order of extra embarrassment to go.

 

Look at how close passengers in the ferris wheel car were to being centre-punched. Think about the consequences of the public reaction to RAA-class aviation if that had happened. It's no bloody laughing matter.

 

 

You are a worryingly sick puppy. Four exclamation marks are the sure sign of someone wearing their underpants on their head. Get back in your basket and don't come out again until you have gotten well, or I'll send someone around with a BIG thermometer to take yer damn temperature..

 

 

JJ, that's useful. (incidentally, I've been keeping a quiet eye on SDS for about five years now,: I first noticed them when I was researching a possible EA81-powered project, and I've been consistently impressed with what they do.)

 

Suggests to me that there are a few different paths that one could take, probably driven by what registration group one wants to fit in.

 

As things stand, I suspect that the 'retain the carby and add supplementary fine-tuning by EFI' approach MAY be a way to get around having to use a certified engine - though that would need to be tested as a concept with CASA before embarking on a project to try it. IF it can be accommodated in the regs, I still think an option for 55 and 24-certified reg aircraft.

 

For 19-reg and VH-exp, a straight SDS system (and maybe clean up the pre-TB intake tract, it's pretty squashed for the Bing and early airboxes at least are not a pretty sight, to my eyes). I think I'd like some electrical supply redundancy, and I also think using a conventional alternator with conventional regulator (CAMit or Rotec) would be sensible. On that score, I like the CAMit one as it provides a bit of crankshaft damping and uses toothed belt, not v-belt.

 

A possible, I'd think, degree of redundancy for the SDS installation that wouldn't stuff things up could be to use a TBI unit rather than just a plain TB with a second system and a manual switch-over. Depending on the sort of flying one wants to do, I guess that could be a 'full-on' TBI set-up if you really feel the need for high-level performance from the back-up unit (you fly out of difficult sites etc.) or even, given that the SDS system is pretty damn reliable, something as simple and pretty cheap as a megasquirt with say dual injectors in a simple tube just before the plenum. Aftermarket TBI set-ups come in at around $2k all up, the megasquirt I think can be set up for about $1k. So, an SDS kit PLUS a redundant back-up set-up might come in around $6k; you'd probably want to be pretty well assured that you'd extend the real, attainable TBO by about double that of what people are typically getting now to look at it as cost-neutral.

 

So, I think, there are a number of options one could consider. The result of all of our ponderings here is, to me an indication that this whole area of getting better fuel mix into Jab engines is very much a work in progress and I am of the opinion that the potential of the CAMit engine to provide (we hope!) something worth adding some thousands of $$ worth of extra-quality fuel delivery gear onto is the reason that all of this consideration becomes worthwhile pursuing.

 

 

Back at Post #10 (first page) is a report on what is probably the highest-time CAMit engine (at least in general flying, not testing!); at the rate it's been putting up the hours, probably has around 180 by now.

 

 

Well, we have quite a few reports - sufficient to make it a believable hypothesis - that the mixture problems on Jabs. tends to waddle around amongst the pots depending on throttle position; however it might well be the case that a bit of research could show there is sufficient latitude that just getting a 'generic' mixture curve correct for the worst pot is sufficiently close that the rest don't matter being a tad over-fuelled. Next better is being able to tweak the curves for individual injectors; best is individual egt-based feedback control..

 

Personally, I'd prefer to have them all running pretty evenly, both for efficiency and for giving the crankshaft a slightly easier life. I'm not at all sure that ending up with say one or two pots running constantly over-rich is ideal for glazing / coking; it won't cause the thing to go BANG suddenly (as long as one keeps aware of compression figures), but it'd be slightly more comfortable to think all those pots are happy little critters for as much of the time as possible.

 

 

I've met him. And I fixed up his damn Thruster some years ago for him, so I have the advantage of knowing which rivets I left out... (we all need a pension plan).

 

 

What do you think I've been -ing saying all along? and isn't FMEA an acronym for Fit a Maypole in an Engineer's Ahem? For you (and only because I'm basically a gentle-natured and considerate soul) , I'll extend the medieval process and include a horse-collar....

 

Still, I'm encouraged that you got there eventually. Been worth every electron.

 

 

Aha! THAT's why you bought #0001 - you're not good with big numbers! I must say, I've long suspected it... Most aircooled aero donks run stoichometric - i.e. the "correct" mixture (nominally 14.2~14.7:1) - up to ~85% power, then progressively richen up to ~12:1 at 100%. The main slide needle in Bings (both by shape & position) controls this enrichment. If you re-needled your Bing to give stoichometric all the way up, then EFI failure should only affect you on takeoff/climb; and you'd kinda notice the rev drop!

If I find out where you are, you are going to get a slapping...

 

Yer missing the essential point that trying to get the Bing on a Jaburi to give decent even mixture is a Sisyphean task - you think people haven't damn well been trying to do this for years?

 

 

Only reason to still use the carby would be if by so doing one could to get around problems of compliance with standards. I'm not sure if this would be feasible, but if you have to run a TCDS'd model Jab engine (e.g. 2200J) and you retain the standard fuel supply set-up but ADD something to it that can be approved under the 'no adverse effect' provision, then you have a mechanism to get the efficiency of the EFI set-up while still retaining the carby so should not need any huge test and certification programme. I do have to say that this is a fairly big IF, but we don't know it's impossible until it is proven to so be.

 

David's point that not actually using the carby fuel system is a bad idea is I think extremely cogent here, and I would not be at all happy with running one as back-up that isn't demonstrating that it works every time one starts up.

 

HOWEVER: I do agree that this is ultimately less desirable than going full EFI when somebody can do the necessary certification work. Given that we have seen authorities (dragged somewhat kicking and screaming, I think) into more acceptance of electronic flight bags etc., just perhaps somewhere further down the yellow brick flightpath we might get a sensible conjunction of regulations and system developments. I'm not holding my breath here, but IF (not WHEN) that happened - and assuming any EFI controller manufacturer can be persuaded to join in the fun, (which is in no way a given), then I'd think that those who have taken the hybrid path ought to be able to use a fair bit of the EFI system they have added as part of the carby-less next step.