Jabiru experience

[Camel]

Very interested in how that works, Oscar. My installation works okey but I reckon it can be improved. I'm about to remove my ram-air ducts and replace them with a simple fence that seals against the cowl. If I can get the sealing right it should cool better, but I need to get as much suction below the engine as possible. Best way might be to totally separate air flow to the oil cooler and the engine, and have a cowl flap for each.I have heard from a source at the factory that someone put a lot of work into a similar setup but went back to standard ram-air ducts.

 

Would be nice to know more before I start cutting.

The Bristel with the Jab 3300 came with a planium fence set up and it was changed at Jabiru, there was a photo of it in a magazine with planium set up. and it belongs to Central west Flying school. Also a well known L4 at Cessnock played with a planium and fence set up I believe but changed it back I think.

 

 

[jetjr]

The Bristell was working pretty well i heard and a lot of time was spent on it, but Jab changed it anyway.

 

I have heard of a few that after much work it made little difference going that way

 

 

[facthunter]

Any method of injecting near the port will remove the danger of having a large amount of piping full of combustible mixture, as you have with a carburettor. Any backfire with manifolds full of mixture can force a lot of pressure into adjacent cylinders causing destructive situations that can fail components of the engine. (Like through bolts, as an example). Nev

 

 

[Oscar]

Very interested in how that works, Oscar. My installation works okey but I reckon it can be improved. I'm about to remove my ram-air ducts and replace them with a simple fence that seals against the cowl. If I can get the sealing right it should cool better, but I need to get as much suction below the engine as possible. Best way might be to totally separate air flow to the oil cooler and the engine, and have a cowl flap for each.I have heard from a source at the factory that someone put a lot of work into a similar setup but went back to standard ram-air ducts.

 

Would be nice to know more before I start cutting.

OK, with a TOCA ( CAMit) installed, you'd not need the flap for a dedicated cooler ducting ( one mechanical thing to go wrong / forget..) My (unproven as yet) set-up is based on using a completely different cowl arrangement to standard Jab; I'll try to get a couple of photos of what we have done later today and post them ( I only finished painting it a couple of days ago). We expect to be making quite a lot of mainly small (hopefully) changes as we test fly the thing, but that's quite a ways off yet before we'll even be able to start.

 

I understand the Bristell original plenum arrangement did indeed work well, but Jabiru were 'not happy' to endorse (??) anything but their cooling set-up. Probably understandable from both sides, that the Bristell distributors went back to the Jab. arrangement as they would have taken on, I suspect, additional liability for the installation that they probably do not need as a load on their resources.

 

As it happens, I spent some time a few weeks ago with the owner of a J160 at Camden who has been most carefully and methodically 'tuning' his standard Jab. ducts and cowl exit - fully instrumented including p-delta recording, and working through an admirably comprehensive set of testing at each change. He now has extremely good and even temps after months of patient work.

 

What I learned more than anything else from that, was that 'tuning' the cooling set-up requires a very large amount of subtle tweaking both to the ram-ducts and the cowl extraction extensions and just how much one needs to understand and work with the interaction between changes from end-to-end of the cooling system. It is of bugger-all use to just look at what has 'worked' for someone else and go with it, without testing and measuring each change along the way to get the balance correct. For example, his revised inlet baffles differ from side to side to handle the different airflow due to the prop rotation and cylinder positions relative to the intakes. He has added fixed extensions to the cowl exits; now is in the process of re-tuning those, as he's found that they are likely just a bit too big and causing a stagnation off the backside at higher climb angles - size does matter, and bigger is not necessarily better.

 

He had already put up 1000 hours with no problems on his first engine in the 160; decided to change to a new engine rather than just to the top overhaul, and added full CHT and egt monitoring with the new installation, that used the existing ram ducts etc.. Was shocked to find that there was up to 40C difference between cht's with the full monitoring - and that it was no.#4 ( the standard location for the single cht installation) that was almost always the lowest-reading pot!. That seems to be a familiar(ish) story from the several years of threads we have had here on Jab. cooling.

 

 

[Oscar]

OK, here's a few piccies of what we've done so far - and it's all VERY theoretical at the moment, but I am taking advice from someone with a lot of useful experience. (paint isn't even hard enough yet to give a cut and polish, so please excuse the, ahem, ' average' nature of it).

 

First: the lower cowl oil cooler intake, 'trough' to fit, and exit ( which will need an additional extractor lip but we'll do that through experimentation) Oil cooler is a 7-row Aero-classics.

 

 

This is how that earlier piccy of the cooler with the ducts attached fits: ( obviously, that's a dummy sump on my 'dummy' engine I use for development of the installation). The ducting dimensions are intended to achieve some pressure recovery through the cooler matrix; they're not perfect for dimensions or shape, but not wildly far off either.

 

 

The overall cowl pair is fairly different from standard LSA55, as you can see: I've tried to get the head intakes to capture more of the prop-wash from a bit further out on the blade than the standard ones, to feed the head cooling plenums, while the second (lower) set of intake nostrils ( which are WAY bigger than they will need to be, but again, we'll cut back by experimentation) will feed individual plenums for the barrels each side, which will ( probably!) have nasa under-barrel baffles as per the 'in-line air-cooled engine' research paper. There's an obvious influence on the overall design from the old Navion-style intakes, which are generally though of as fairly good for purpose. The new spinner is almost, I think, as large as yours!

 

 

 

[Old Koreelah]

Star Wars Stormtrooper!

 

 

[Oscar]

Actually, from dead ahead, it's more Munch's 'scream', to me: (this is the first test pull off the moulds, in polyester and using some Bunnings ute mat as a stiffener) - I think of it as the next evolution of a 'Howl Cowl':

 

 

We're going to use the 'long flange', so it's 50 mm longer than a standard LSA55 cowl. Our original cowl was designed for the 1600 engine, and then 'modified' to be used as the test mule for the 2200 - and it was a dog's breakfast. Rubbing on no 1 head and rocker cover; too tight for the exhaust tubes and muffler which had severe charring ( bloody wonder it hadn't caught fire, actually).

 

Was hugely more work than I anticipated - not from the changes to the intakes etc. but because the original ( very, very early LSA55 moulds - ours is airframe #50) were rough as guts, to be honest. Naively, I made the moulds accurate - and then found that there is as much as 10mm difference in the fuselage in various places, side-to-side, so had to do a whole heap of work to blend in the shape to the actual fuselage. As you can see in the previous piccies, we're using piano hinge to join the sides of the top and bottom cowl, which necessitates a pretty straight run for the hinge-pin - the original LSA55 cowls are very pinched-in, and held together by simple over centre catches. We've gone for camlocs for the top cowl for both speed of removal and an easy visual check of security on the D.I. - 6 at the back and two at the front, and with the hinge-pins inserted, the whole assembly is gratifyingly rigid. Made using 1.5mm Coremat and lc3600 resin with 25% aluminium trihydroxide on the final inner layer for fire-resistance, has come out about 1.5 kgs heaver than standard.

 

Found - fairly recently, and OF COURSE it necessitated more work in fettling the cowls - that the firewall is not particularly accurate in location, and the engine offset was nowhere near the 1.5 degrees of modern Jabs. Whether it came out of the factory like that or has been subsequently 'repaired', I can't tell from the logbooks, though I have a sneaking suspicion that the latter is the case. However, IF it is 'factory', that would explain some of the 'nervousness' for landing LSA55s, since power application in the final stages of landing plus the small tailfeathers (which we've also replaced..) would cause the things to squirm.

 

We've done a great deal of work in both repairing the crash damage and just upgrading things, and I have to admit that the early Jabs were really quite rough in construction - and yet, a vast number of them are still faithfully serving their owners. For whatever sins people wish to lay at Rod Stiff's feet, when you really get into the nitty-gritty of the things - down to cutting up the original mainspar laminations as we have done to manufacture new rear drag stub-spar fittings - you simply have to have admiration for the way in which he developed a philosophy of 'cheap, simple, safe and effective' structural design and construction methodology and carried that through into a hugely successful commercial venture, by the standards of the industry. I'll fly in ANY Jab happily, no matter how old.

 

About two weeks ago, I had a long session of examination and discussion with the owner of an almost brand-new J170D - and honestly, the fit and finish was really, really classy. It was like looking at a Honda S2000 by comparison to a Bug-eye Sprite of our aircraft, I nearly slipped and fell on my own drool. People get carried away with what George Markey called 'the paint': assuming that the final finish they see is a mark of quality throughout. However, the lineage of Jabs. is proof that what lies underneath is 'quality' as seen by an engineer - not 'quality' as perceived from the fabulous images in the glossy brochures.

 

 

[Russ]

Ok.....my 2 bobs worth,

 

when i first got my 160, CHT would climb HIGH in the green, so stepped climbs it was. My only sensor was on the LHR head.

 

Acquaintance put me on to "his" mod.......so we redesigned my lower cowl lip ( pics attached )...........since this mod, i can maintain full power climbouts till i reach the moon, same sensor,same place, my temps hold mid green. In cruise temps are JUST in green.

 

Seems to work............BTW, i'm just sayin here......im not suggesting you all do it.............disclaimer

 

 

 

 

[bexrbetter]

I think of it as the next evolution of a 'Howl Cowl':[ATTACH=full]39231[/ATTACH]

Holy Cowl!

 

 

[Oscar]

Better cowl extraction is absolutely the first step along the way: better p-delta from the ram ducts results. Getting decently even temp across all heads, is important too and it needs fine tuning. Do you have full CHT monitoring? LHR head ( no.#4) is usually the lowest in most circumstances, and just your cold-junction location COULD be making a difference to what you are seeing reported.

 

And for ALL of that - we KNOW that some operators have consistently fine results with even entirely standard set-ups: what would be terrific to know, is exactly what conditions their engines are operated under: how they manage their ground running and climbs, their fuel, the ambients they operate under, their maintenance regime..

 

 

[Old Koreelah]

Looks awesome Oscar. You're getting lots of air into the front. Sounds like you've built some fancy ducting from the lower intakes to the barrels. Ideally I'd like to take my air in under the front and let it draw up thru the fins to take advantage of 'hot air rises' but that idea, as you say, is better suited to a pusher installation.

 

 

[Oscar]

There has to be a trade-off between just stuffing a lot of air in and getting it out, and cooling efficiency vs cooling drag. The air has to: a) be sufficient; b) have suitable velocity across the heat transfer areas; any more than that and you're wasting energy. Too much velocity will produce areas of stagnation.

 

People like to contrast the reliability of Lycomings and Continentals vs. Jabs, with Jabs coming a poor cousin at best - but most don't realise that Lycoming ( for one, I am not sure about Continental) will NOT guarantee any of its engines unless the installation has passed a Lycoming factory audit. And you can NOT change the approved installation.

 

 

[Jabiru Phil]

Jeez, the old Fordson petrol kero tractor I learnt on had a screw that operated the air flow to the radiator.

 

The temp gauge sat on top of the radiator cap.

 

Adjust accordingly to keep in the green.

 

Not rocket science IMHO

 

 

[jetjr]

Russ, similar cowl mods are detailed on an SB re cooling of training aircraft.

 

A few types detailed depending on score the aircraft gets froma series of questions

 

I think you can buy a glass on mould for this from Jab

 

 

[Geoff13]

I might be a bit simplistic, but if I purchased and $80G plus item like an aircraft, I would expect it to be capable of performing to the manufactures quoted standard without having to spend hundreds of hours modifying and stuffing around with the damn thing. If you bought a car that overheated if you accelerated to hard it would go back to the supplier fairly quickly. In fact if you bought anything that is not fit for he purpose that it is designed then you would be fairly vocal about it.

 

This is fairly close to home for me because the one plane that my wife actually enjoys flying in of the half a dozen she has been in is the J230. I am certain that if I purchased a J230 she would be very happy to come flying with me whenever I went.The problem is with the CASA restrictions, the aircraft will not be able to do some of the things that I would like and the perpetual discussion about how to keep Jabirus in the air and the hours needed just to do that simply makes it a very unattractive option to me.

 

I am not worried about servicing or regular maintenance that is not a problem but the hours of fiddling and changing things which on an LSA are simply not able to be done anyway amazes me that they are allowed to sell them.

 

 

[DrZoos]

Agree ...what is your time worth...the time you have wasted Oscar is amazing...but in all honesty if you went and pulled beers for $20 per hour you could have purchased a rotax and flown the thing the entire way around australia , fuel and maintenance costs included ....

 

 

[Oscar]

Agree ...what is your time worth...the time you have wasted Oscar is amazing...but in all honesty if you went and pulled beers for $20 per hour you could have purchased a rotax and flown the thing the entire way around australia , fuel and maintenance costs included ....

Except... that I'd have to have a new engine mount engineered and built, add weight to the tail ( I only have 430 kgs MTOW, remember...), buy a new prop, etc., have it flight tested and approved... Ian Boag did the changeover with a second-hand 912 and he reckons $40K for the changeover..

 

And I'd still have to make a new cowl for the rotax. And with the extra weight, I'd be down to such a low max fuel load - even one up - that I'd be flying between refuelling points not much more than 2 hours apart, at best. Plus which - and I respect all of the good things that Rotaxes represent - I just don't like the concept of the shaft construction. A personal prejudice and I have no reason nor interest in spouting off against them, it would be silly anyway, but that's me. My engine has a lot of the good CAMit stuff in it already, and when we've done the work we want to do with at as a research platform for a few things, that engine will go full CAMit upgrades.

 

Plus which - I don't much like beer, I'm a red-wine man, myself.

 

 

[jetjr]

Its a fair complaint Geoff and the whole concept of LSA is to blame. If it were called a factory assist homebuilt or experimental or something else people wouldnt have this expectation of turn key perfection. Its been recommended several times to Jab that they spend more time getting them tuned and tested before sale.

 

Restrictions on LSA are onerous and your locked into ones persons view of how things should run and CASA's view of that.

 

Other way to view it is to cost the improvements at time spent, maybe $5K, and add it to the cost of the aircraft.

 

Youre still way cheper than similar performng options.

 

Buy a used one, move back to E reg, fit a new Camit and optimize that.

 

 

[Oscar]

I also agree that Jab. should have done more to optimise their cooling ( Jab USA and Jab SA have, I think, both progressed further than Jab Aus., though I'm not really across all of the Jab stuff from either country.)

 

From what I glean, Jab. has now bitten the bullet and includes a Dynon EMIS (EFIS, perhaps??) and full cht monitoring (at least) as standard. I'll join in the chorus of any choir singing 'Hallelujah' (Handel's version) to that. It is years overdue.

 

I think - though obviously we will need to see the runs on the board come in - that that will make a very, very considerable difference to the reliability factor, because operators will be getting the info. they have always needed to really know what's been happening up front. As a 'secondary effect', I think it will also point out to Jab themselves pretty forcibly, whatever changes they need to make - they can't argue with repeated instances of recorded 'poor' performance. Recorded performance from a factory-installed monitoring system removes the argy-bargy over whether it's 'operator' or 'aircraft' (lumping both engine and installation into one category here).

 

Why didn't this happen years earlier? Well - and only Rod Stiff could tell you for sure, but AFAIK he's always been very keenly aware of 'price point', and most people would agree that you got a pretty damn good airframe for the money; very, very good for the 230 in particular. 'Pity about the engine', you can well say with justification.

 

Here's a small story.

 

About five years ago, my co-owner was part of a proposed syndicate to buy an LSA. They looked very hard at a number of the leading options: Pipistrel, Sting, Flight Design, I think also Tecnam. Enough members of the proposed syndicate were dubious about Jabs so they were not on the 'list'. However, as it turned out, they had pretty much all mentally pencilled-in a purchase cost of around Jab. money - even if only subconsciously.

 

As they looked through the offerings, they found that to get the Euros actually in the state that they were presented in the glossy brochures, was tending to get into the $120K+ bracket, by the time some 'fruit' was added to the basic cockpit, you added insurance etc. (the $A was then I think about where it is now). To cut a long story short, that syndicate never progressed to any purchase.

 

For all of their 'problems', Jabs. were the mainstay of the training fleet, and most operators managed to keep in business even with handling 'the problems'. Some had a bad run, some had a great run out of them. We've all banged the drum about that to the point where I don't think it needs another rattle. However, I think it is not an unreasonable contention to say that on average, Jabs. have been - with all of their 'problems' - sufficiently cost-effective to operate that most FTFs could offer reasonable cost for training, that has seen the expansion of Recreational Aviation grow very healthily over the period when Jabs. were, in fact, pretty much the 'standard' for operating costs. With tongue firmly in cheek, one might say that students came away from training on Jabs. with a very firm idea of the necessity to be aware of and handle forced landings, and maybe that isn't such a bad thing.. And, at least they DID come away from such training intact.

 

 

[jetjr]

Jabiru also need to configure and turn ON recording in the Dynon EMS units

 

Ive seen two, both with this feature turned off

 

 

[Oscar]

Well, that's just nuts. It is in everybody's interests to gather data, and hopefully, to share it. It is the best way to gather real-life experience and be able to correlate both similar and different results, both of which will help point to areas for attention ( including the cooling effectiveness and 'real-life' operator experience), and develop greater understanding of what and why - thus allowing the refinement of 'how' to progress.

 

 

[facthunter]

Engine handling is part of flying piston engined ultra lights as well as ANY piston engined plane. Cowl gills(shutters) would be a good feature if the engine was over cooled (potentially) and regulated by the shutters. (cowls) Extra efficiency is available with properly designed cowls. Installations vary and have to be fine tuned to work well. ALL engines are responsive to forward speed V/s Power output. You can also overload any engine by overpropping it. You then introduce the mixture control (or lack of) Another variable. The Bing Carb is nothing special but does a job and not expensive. A lot of people don't really understand how it works, and that includes some so called "experts" in the FAA. Nev

 

 

[DrZoos]

One day the dinosaurs will welcome EFI...by then they may understand the bing carby

 

until then youtube may help

 

 

 

[Oscar]

There are always compromises: if there weren't, we wouldn't all agree ( and I think we just about all DO agree, in general terms even if sometimes we get frustrated in specific cases!) with the old saw that 'you can have it light, or cheap, or reliable (substitute fast, good-handling, whatever floats your boat) - but you can't have all three.'

 

Even Bex - who may yet make a breakthrough, he has as good a chance as anybody - has indicated that his development engine won't be the 'lightest', because he can't afford to throw the resources that Bombadier have to that side of the equation. And fair enough to him, I say - that's a realistic and honest position to take, and one that I believe we can all agree on. There is NO silver bullet here, for anybody/company, and his engine, just like others, will represent the answer for some and not for others.

 

Using the MTOW as the Damoclean sword for acceptability for a class of aircraft is quite possibly the single most pernicious hurdle preventing a wider range of aircraft and engines to be offered, even within a generalistic notion of price-class and 'risk'. Already, we are (finally!) starting to see cracks appearing in the imperatives by the certifying authorities against this: witness the ICON, the weight allowance for installing a BRS etc. If there were some magic line of safety flowing on from the MTOW restrictions below which things are 'safe', then it is as simple as this: if the aircraft is 'safe' at the mandated MTOW without a BRS, then by adding a BRS it would suddenly become 'unsafe' for every damn take-off and landing with the added BRS weight.

 

That is an evident and palpable nonsense, just as 'zero-tolerance' application of speed limits is an evident and palpable nonsense. For that matter, a few kts +/- of VSo is a bloody nonsense: it has the implicit caveat that ALL pilots will be able to control their aircraft sufficiently accurately to achieve its VSo in order to achieve its mandated 'safe' speed. I believe it is fairly generally accepted that LSA-class aircraft are more demanding to fly than say a C172 - but I have not picked up that a C172 is 'unsafe' to fly into and out of MOST airfields that are routinely used by LSA-class aircraft. A competent pilot can get into and out of ANY airfield that all but the best of the STOL-type LSAs can in an Auster, a Citabria/Declathon/Champ, Super Cub, Tiger Moth..

 

Once again, let me point people to Phil Ainsworth's excellent exposition on why Jabiru embarked on producing its own engine: http://www.aeromech.usyd.edu.au/AERO1400/Jabiru_Construction/jabiru.html While this is specific to the whole Jabiru story, the general considerations Phil pointed out, are entirely relevant across the spectrum of Recreational-class aircraft.

 

Jabiru did NOT embark on engine manufacture because they saw it as an untapped 'goldmine'. Rod Stiff had designed an aircraft with certain basic parameters including the methodology of manufacture and the inherent safety of a particular design and materials specification. That basic philosophy produced - and has remained throughout its various incarnations producing - remarkably safe, decent-performing, good-handling and extremely reliable airframes.

 

If I may point people at the statistics fairly recently published from the USA: https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCMQFjABahUKEwj1vNamgoDJAhVFoZQKHWE1Baw&url=http://flightdesign.com/wordpress/wp-content/uploads/2013/11/The-Aviation-Consumer-LSA-Accidents.pdf&usg=AFQjCNGtRIqF1hpBcB8i0THTv-5kgfVryQ&cad=rja

 

Jabirus come out extremely well.

 

The only aircraft immune to engine failure, DO NOT HAVE ENGINES. That statement is true for everything from Airbus A380s to Cri-cris.

 

As for the Bing: it has reasonable altitude mixture compensation. It doesn't afford the best mixture calibration, but the corollary of that is it doesn't require human intervention for adequate mixture control. Both Jabiru AND Rotax, have elected that that is the better option for the 'average' pilot skill.. On general experience of average pilot's ability to maintain LOP, that seems to be not silly. I know of one CASA-approved Test Pilot, very much capable and experienced in using mixture control, who has elected to use a Bing 64 on his Rotax 582 installation. His rationale: more damage has been done to Lycontintels by mishandling of LOP than makes up for the benefits you get from the advantages of mixture control. I just want to fly. The Bing takes that element of concentration out of flying.

 

 

[Geoff13]

Buy a used one, move back to E reg, fit a new Camit and optimize that.

So what would be the procedure to Convert one to VH Experimental and put a Camit in it, and then would it be possible to up it's MTOW to the 750kgs it was built for rather than the paper MTOW it operates under in RAA?

Would all of that even be possible.