ianboag

We talk about "homesick angels" here. Did a test for best rate of climb (two-up) from 1000-3000 - ft between 70 and 90 KIAs. It came out at about 850 ft/min for all the speeds we looked at - at 70 KIAs the problem is having one's feet higher than one's head. Interesting - that's how mine (and the YCAB one) work. It's ally - think of it as a "false firewall". Looked like a daunting bit of CRC until I found I could get the whole thing done by a local water-cut outfit for $300 including the metal. I doubt that putting the plate on the front of a standard Jab mount would work as everything would be too far forward. Anyway, they have something that works and who cares?

Now where have I seen THAT? I imagine that a 170 does it even better than my 160 .... I must admit, there were days when I felt that carrying a passenger in my J160 got all interesting on takeoff with a no-wind hot day

Been "bogey" all my life. It's why our he-dog is Humphrey and the she-dog is Lauren ....

There is a J170 west of Melbourne with a 912s fitted. I have quite a few photos of the install I'd be interested to see the pix. PM or send to [email protected] From what I understand of the Oz rego system, it would have to be a 19-rego? The paperwork for a 24- plane is just waaaay too hard.

[email protected]. Drop me a "hello" email and I will explain why it will never happen

True, although that was a bit of a "rush of blood to the head" thing. Me and the boys at YCAB have the world's only two Rotaxified J160's. There are unlikely to ever be any more. It goes fine, but for the $, time and stress involved I should have just flogged it off and bought a Tecnam or whatever. I gussied up the paint job while I was at it. Not that this has anything to do with the thread ...

And now that I remember - last year there was a 3300 on our field having the through bolts done. After the new bolts were installed and torqued up, the prop didn't want to turn. Cases fretted out at 700-odd hours. Funnily enough the top end was all good ... The engine was biffed - based on past experience, there didn't seem to be much point asking Bundy to care.

My J160 came from the Adelaide Soaring Club. After getting it, I read in the logbook that the original engine was replaced at 500 hours because of crankcase fretting ... Dunno if they had to pay for it. Just anecdotal of course. And for the avatar crowd, I am truly a bogeyman ....

In the pre-war days, British engineers tended to be "practical chaps" not contaminated with the likes of university engineering learning. That's why a Spitfire took 14000 man hours to build vs 6000 for an Me109. The Merlin was designed by practical chaps at Rolls-Royce. Their development path was to thrash it until something broke. Then they looked at the wreck, beefed up the broken bit and did it all again. Then it went into service ... from the Wikipedia page ... Initially the new engine was plagued with problems, such as failure of the accessory gear trains and coolant jackets, and several different construction methods were tried before the basic design of the Merlin was set.[14] Early production Merlins were also unreliable: Common problems were cylinder head cracking, coolant leaks, and excessive wear to the camshafts and crankshaftmain bearings.[15] The cheerful bit is that it ended up as a pretty good engine. Does this seem familiar? Do the factory people have what it takes to sort the problems faced by owners of Jabiru engines?

Bit of thread drift going on here. I have been part of it and apologise. 912's last longer than Jab engines, but this is not what the thread is about. If CASA gets its act together the next thing would have to be be some specific deliverables for Bundy to meet. I would wager a reasonable sum that noone in CASA has any concrete idea what these targets might be or how to monitor compliance with them. The deliverables would be "to make Jabiru fix their engines so they break/wear out less often" and compliance would be deemed to be a state where that is "observed to happen". I would guess that CASA has never done a job quite like this before and CASA probably does not have the skills to do anything useful in this poorly-defined furball. I would also guess that the stats we have seen are about as useful as the proverbial knob of goat dung. If I have an early top, or replace a broken flywheel bolt or two, or lose leakdown because of gummed-up rings, or even if my engine sucks a valve, there is no obligation to report it to anyone. Bundy is often less than helpful to those who pass the word back ... Personally - I find some of the engineering stuff a bit bewildering. Through bolts pop because the joint they are securing moves and bending-back-and-forth fatigue snaps them. That is how clamp joints fail ... always ..... The only real answer for an under-performing clamp joint is "more clamp force". Bigger and/or better bolts .... Ditto with flywheel bolts. The extensive use of Loctite 620 seems to be a peculiarly Jabiru thing. Lyc/Conti procedure is to oil the through bolt threads before assembly and torquing. I am told by friends with metal-bending experience that dry torquing is a nono. Go figure. I believe the engine could be made into something that lasts longer and breaks less. If that made it a bit heavier, so be it. And now Camit is making a better-Jab-that-is-not-a-Jab, but regulatory, IP and inter-personal issues cloud its status. A farcical situation where some heads should be banged together. Some of the heads to be banged should be CASA ones. Disclaimer : I'm a Kiwi who flies a microlight in NZ so none of this has any regulatory impact on what I do. I'll leave now :-)

TBO has never inferred you don't have to do work on it if checks (required) indicate a situation requiring it .. it is an upper limit of operating time before the engine has to be stripped and inspected. Might as well just read a number (that few achieve) off the ceiling. The extension " on condition" is a bit unusual Not in the GA world. Lots of Lycs, Conts and Rotaxes get there. Never heard of a Jab that did ...

The fact that upgrading of parts to newer and better is such a good deal is one of the reasons why so many take up the offer. The engine has been around for 15 years - when does it stop? IF you can get a nil hours engine for a bit extra why would you NOT do that.? Much has been made of the inference the engine failed, when the engine hours are way less than the aircraft.. Nope. Just that all these engines that were sold as "1000 hours to top overhaul" and needed it at 500. FAILURE may not have occurred at all. See above If you are a fit and forget person you don't suit an aeroplane environment, because an aeroplane is a "check everything" situation. Haven't seen the manufacturer pointing THAT out either. THINK aeroplane. I don't know how many people I have felt the need to say that to. Were any of them flying behind 912's .... ? As you can tell, I'm Ian Boag from Palmerston North, NZ and over time I have done my bit for Rod's pension plan. You must be Nev Facthunter from ???

If Jabs were advertised as "likely to need a top overhaul at 500 hours" and/or "possibly a good idea to replace the outdated engine with a new one before 1000 hours" .. That info is widely known, not hard to find out. Not mentioned by the manufacturer anywhere I have seen. If you buy an experimental non certified aircraft engine and expect not to have substantial improvements or repairs in 750hrs and 10 YEARS ownership your not ready to own an aircraft. "You're". Unless the power unit is a "912" ... I talked to Paul Crowfoot before Rotaxifying my 160. I said "no doubt makes a different noise in the cockpit" to which he replied "and the good thing is that it just keeps on making it " :-)

I have owned Lycs and Conts though and couldn't argue with that. The Rotax 912 seems to be made of sterner stuff. As I recall, new pots, pistons, valves, guides made a pretty good hole in $10k when I did mine. "OK" was not how I looked at it. If Jabs were advertised as "likely to need a top overhaul at 500 hours" and/or "possibly a good idea to replace the outdated engine with a new one before 1000 hours" I wonder how many they would sell .....

Have a look at the "for sales" on the RAA and Jab sites. A third (give or take a bit) of the engines seem to have had a top overhaul at about 500 hours TTIS. I know that my aircraft had a new engine fitted at TTIS 500 hours (long before I owned it) because of crankcase fretting .... Go figure.

And the moon is made of green cheese. These engines have been in production for something like 15 years with 3500-odd made and this is a new problem? Adelaide Soaring Club proudly get to 1000 hrs as does Chris Stott and a few others. On the other hand Paul Crowfoot at Warnervale Rotaxified his 160C after three or four engines broke in a five (?) year period. One assumes that the offer will be something like - now that the problem is solved after 15 years, the factory will "fix" things at your expense. Wow. We don't have a dealer any more in NZ. We did a few years ago - he was real keen - ran a flying school in Tauranga - saw a Jab and loved the concept. So he went to Bundaberg and bought a new 230 and a not-old 120. Flew them back to NZ across 2000 km of ocean and started heavy duty training - about 100 hours/mo for each. Loved it right up to the point where the 230 popped its (starfish) flywheel bolts, landed in some inhospitable country and became a kitset. It went back to Bundy where it was explained that it was probably a maintenance problem - his LAME that did the 100 hour service/inspections was not up to snuff or something. Shortly after that, the 120 popped a pot in the circuit (through bolt failure) but landed OK. Same LAME every 100 hours, so what can we say? A new engine was therefore the story for the 120 - at 700-odd hours there was no question of warranty. A new engine was purchased and installed. At the first month's service it was weeping oil round the cylinder bases. That means the pots are moving and it's just a matter of time until a through bolt breaks from fatigue. Bundy didn't want to know, so he sold the 120 for a knockdown price and quit running a flying school. Rumour has it the exercise cost him a 6-figure sum. I realise this story is anecdotal. There's more, but this will do for now. There is still no agent in NZ.

So, at least round $40k and months of downtime, Would have been nice if $40k had covered it ....:-( It was done for Tony Grills to put an 80 912 into an early 450 kg Jab. Apparently worked OK but load capacity was small person plus smaller person plus two hankies for luggage and three cups of fuel ....

The Caboolture J160 is not a factory install. It is not an STC. My J160 has more or less the same mod, but here in NZ where the regs for micro lights are a bit more relaxed. The YCAB machine was converted using an EO specific to that aircraft.

I went to Tassie once and they all looked sideways at me every time my credit card came out. All I could say was "I wish". I still had to pay for the brewery tour and t-shirt ... Orright orright. Off topic. Sorry.

Chill. Calm down. Isn't this where this whole thread started? Thanks. I'm pretty comfortable with the theory in the Tennekes book. Also professional. I would be very surprised if "your book" and "my book" have any significant disagreement. Also cost something like $25 ... Fair enough. In my 20-odd years of uni lecturing (engineering school) I met plenty of the type of folk you describe. Yep. AoA and all that .... The people who say that the flow splits, speeds up over the top surface, creates a higher velocity (lower pressure) area before the streams rejoin at the trailing edge. The "suck me up into the sky" folk ....

Wow. More heat than light here in some posts .... I can recommend a book ... "the Simple Science of Flight". Henk Tennekes (the author) is a (Dutch) professor of aerospace engineering. I believe he has done a bit of flying too. He talks about the unifying principles that govern flight of all objects bigger than a gnat up to the size of an A380. Energy consumption, lift, drag, most "efficient" airspeeds ... etc etc. Why a 747 is more fuel efficient per seat than a mid-size car (!). Why bigger planes fly higher. Fuel calculations about little birds that fly huge distances. All good stuff. It is written in a fashion that anyone moderately technical can follow - not a textbook, just an interesting read for those of us who would like to understand stuff a bit better. more info at http://mitpress.mit.edu/books/simple-science-flight On lift he says the same as CAG. Lift is the upward reaction to a downward stream of air generated by the wing .... in an open system like a wing there is no requirement for two air molecules that separate at the leading edge to end up next to each other at the trailing edge. There's fluid mechanics maths behind it, but the detail is a bit complex for most of us. I agree that so long as the wing keeps us in the air, we don't really need to know too much about the physics. Good ole aviation. PL exam questions about the % oxygen in the air or UV in sunlight. Mastery of a circular slide rule that was cutting edge stuff in the 1940's. Weather forecasts written in pig latin about the time in London. All stuff every pilot should know. But it does seem bizarre. We are taught that the plane is sucked up into the sky by a low pressure zone on the top of the wing and it just ain't so.

For those who want a simple explanation. The wing flies at at finite angle of attack to the air flow that hits it will get deflected down and make lift The top of the wing is cambered for drag reasons and the stuff that comes off the back of that is headed down too which all helps. Think of flat wings (the desk fan) and symmetrical ones (any aerobatic plane) and you will figure out where most of the lift comes from .....

But the lower surface contributes zilch at zero AoA ..... probably makes it a bit harder to stay up there

And of course a helicopter rotor is another wing going round and round .... does it suck or does it blow? I'll go with "blow" on that one too. Try flying an aircraft at zero angle of attack and see how well the "top wing suction" keeps you up there ....

A propellor is a rotating wing. Does it suck or blow ... ? I'll go with blow .....