Bob Llewellyn

Tempting, but I don't know you ... Does any other Jab jockey want some? Is it worth generating some?

Mumble - I think "Metalman" had a point - headphone jacks get cycled rather more frequently than car fuses - however, the principle of reducing failure probability through quality does have a place in aviation... it's why i own thrusters, you mark my words...

Ooooh! Oooh! no! Ohm's law! Think a resistive equivalent of Standing Wave Ratio! Look, it's quite verifiable that when you are sitting in the silent cabin of your FlightDoodle 30000000 (background noise 3dB(A)), listening to "Bolero", the sound energy ratio of the piccolos will be less (compared to the Oboes) than the original Orchestral score! You can ONLY reduce this unwarranted attack on artistic integrity by gold plating your unsoldered connectors!

Most jacks are nickel plated or stainless steel; the oxide film is invisible, and should stay that way unless you use 'em for stirring acid or Toowoomba town water... however, running a low impedance set of speakers, the voltage drop across the oxide film becomes a measurable %age of the total power. As aviation does not use 4 ohm speakers on 6 volt systems, the advantages of gold plating are pretty moot. However, that's the basis of the argument for hifi freaks...

Electronic reliability is assessed under MIL-HDBK-217; to do which, you have to have the circuit diagrams AND electrical loadings of all components. Without these things, the aviation FMEA cannot be done. Without a credible FMEA, no basis for Approval exists. Carburrettors are mechanical, and FMEAs are simple; also, stacks of failure probability data exists. Mechanical fuel injection is as simple to analyse, and generally will have a lower probability of failure, than a carby. If Ian Bent couldn't produce a simple, light, cheap mechanical injection pump - remember, it's very low pressure compared to a diesel pump (which is what Kugelfischer adapted, hence size & weight) - then I'll eat a CAMIT 2200 (with salt)...

They b----y know if they're trying to flow through oxide! The gold is an anti-corrosive, looks better than vaseline (smells better too?)

The fuselage carrythrough between the strut pickups is beefed up in all Gazzles; most, if not all, 'Foxes came out of the factory with the lighter tube, which should be reinforced. The Blackwater accident investigation concluded that the aeroplane had flown threw horizontal "rotor" off the mountains, and the combination of reversing acceleration and extreme pitching moment of the airfoil caused the front lift strut to first buckle, and subsequently fail in tension. BCAR-S (CAP-482) does not specify a Vb; the gust factor is assumed to be catered for by the 4G limit manouvring factor, but add the highly cambered airfoil and the margin of safety can disappear. The Gazzle has essentially the same airfoil, and very similar structure in the wing, so I'd be taking it easy in turbulence.

Look, if we were MEANT to use EFI, Kugelfischer wouldn't have made mechanical fuel injection for petrol engines!

Get a 503 ... both EGTs work most of the time, and I've never had a coolant leak!

Cool! Can i quote your details on the TOSG site?

Dazza, are you trying to apply logic to Certification AGAIN? You silly, twisted boy... ps if you like a J2200-engined Drifter could be made for you

Beats me. The drifters are labour-intensive; on a per-unit retail cost basis, a 582 SB is not far off a J-120 price... inherent in the design; they can't be made less labour-intensive and still use the same TC. But they ARE TC'd by the NAA (CASA), unlike LSA's good ol' self certification... though the 582/prop combo limits the operational areas. The 503 WD and 582 SB both have quite adequate performance in every area but top speed; but if you want a Lightning Bug, buy a Lightning Bug. With the price of PH aluminium tube going through the roof, and an average Aussie wage of $800k or so, the alloy tube / Dacron solution just ain't cheap no more no more. W.R.T. the factory sitting still for a while, they must have invested at least half a million dollars in getting production-ready; and on about a 5% direct profit margin (i.e. a loss after paying interest on the development costs), very few people were putting their hands in their pockets. And that was before the GFC - I doubt much has changed now; I suspect they're just being optomistic again. The Drifter is a TC'd aeroplane that can be used for training; they're known to outlast 10,000 hrs; and they're forgiving & fun. But where's the money?

Ive met a couple of heads of Certification, and of Ongoing Airworthiness, and at least one Powerplants, and an Acting Director, a Director, and a Deputy Director, and a head of Legal Services, and most of Engineering Services when it existed - all in a professional capacity - and I find a great deal to blame in CASA. I find more to blame in various Ministers for Aviation, and those with Aviation in their portfolio. And the AAT has degenerated from its original high ideals...

Dunno if they did, but I saw the bits; it was quite repairable... a virtue of glass / room temp cured epoxy. Takes me back to doing some work experience with T&J Glider Repairs, or whatever Tom called it at the time (last century)...

Authority on maintaining a Civil Aviation Safety Authority as required by ICAO to allow VH- aircraft to fly internationally. So wtf do they have to do with Recreational, Aerial Ag? Justify their existence - and it looks good to journos; if the "Safety Authority" is buggering around with, say, Ultralighting, then it must be safer because of it?

LOGIC??? what's logic got to do with certification???

Ok, I know more about airfoils, but Occam's razor says I could be right... where's that darn tinfoil hat?

look, it was sucked up by an alien spacecraft and taken away, and the whole search thing is just a smokescreen because China has been negotiating with the aliens, and Vladimir Pootin is afraid the aliens would accept the CCP's world view, whilst Assad is trying to make Syria an Alien Economic Zone; Iran has got into bed with the USofA, who are negotiating with DIFFERENT aliens.... it's SO obvious... everyone knows the Anzani engines on the Handley-Page 777 overheat if flown over the ocean for more than 2 hours. The reason for the lack of radar evidence is because the French were testing their new radar cloaking device fitted to the Mirage-4s, which are intended to let them nuke Madagascar with plausible deniability, to get rid of the bubonic plague. In the meantime, the Australian Greens are losing ground in Tasphobia because the aliens in contact with the USA have given a demo of their mass mind control ray to the republicans...

Under LSA, only the manufacturer can Approve mods. Under any other certification category, a Part 21M person must Approve it. As applied by CASA, Part 21M is almost useless, and most of the CAR 35s (old reg for mods) have retired / pissed off. CASA have successfully nearly exterminated the modification & non-standard repair industry in this country. Because CASA do not understand the relationship between engineering, airworthiness, certification, and safety.

yup, that's it. NACA Report 664 shows in detail the relationship between the tested flap nose profiles and the shroud / lip at several deflections; it's of note that the flap first drops down, then shifts back and up as the angle of deflection increases. This maintains sufficient energy in the jet of air impinging on the flap nose (and flowing over the upper surface) to avoid separation. The motion is quite complex, and very minor geometrical errors will lose a lot of the targetted performance. Most light aeroplanes use a single hinge to move the flap, which can only be optimum for a single deflection; but most light aeroplanes do not have a shroud OR lip configuration within half a mile of correct at ANY deflection.

"Zis problem is honly a problem if ZE ENGINES ARE OPERATED INCORRECTLY!! (!!!) Zere is NO FAULT VITH ROTAX, BECAUSE ZEY ARE ROTAX!!!!!!!!!!!!!!!!!!!!!!!!!!" Nothing to do with effective monopolies and fear of litigation of course...

<reply to headintheclouds> I presume we're both talking about a stall speed reduction, from the "clean" (no flaps / slats / blowing / suction / doovers) value, to 60% of that speed - for example, a reduction from 60 kts clean to 36 kts in landing configuration? Without splitting further hairs, such an aeroplane could not be made certifiable under LSA; would not have much utility within the LSA weight limits; does not comply with the LSA "simple aeroplane" concept; and would require a lot of engineering, development, and money to achieve. A solution to the very low stall speed aircraft exists, however - they're called "gyrocopters". The painful reality Dafydd keeps alluding to, is that any certifiable aeroplane optimised for ton-miles per dollar-hour will find it's flap power to be limited by pitch control authority. There is one known "improvement" to be had (in this respect) over the single-slotted hinged flap, which is the Fowler; by the NACA data as plotted in A&vD, a lift coefficient of up to 2.8 (2D) can be had with about half the pitching moment increment of simple hinged flaps. The Fowler has the additional benefit that, when the deflection is increased, the Clmax decreases slightly, and the drag goes up markedly. This means that one can use them as landing flaps in the high-drag position, and - if a balked landing becomes necessary - dumping a notch of flap both reduces drag and increases the available lift. I suspect that this is now considered too complex for a "pilot of average abilities"... The downside of the Fowler is the mechanism required to push the flap 0.3c (or whatever) rearwards... especially as the cable interconnect used by Cessna is now frowned upon by design standards*. *Certifying Authorities actually; as the flap interconnect is also the flap drive, and is a complex system with a bunch of single failure modes resulting in catastrophic accident conditions...Since I have yet to see any recreational aeroplane with a properly-shaped flap shroud - despite the data having been in the public domain for the last 80 years - I have to conclude that most LSA designers aren't serious about keeping stall speeds down.

I'm sure the billet 'cases on the jabiru are not as good as the cast* cases on the 914... everyone knows castings are better than billet *Rotax use die castings, which inevitably suffer some degree of inclusions and shrinkage stress. Contacoming use sand or permanent mold (glued sand) castings, generally in 355 (Al-Cu); the alloy overages in service, and it's a contest between the alloy getting so soft cracks don't propogate*, and the shrinkage stresses relieving by breaking something. The Jab cases have near twice the yield strength, and don't age at anything like the same rate (ie they retain their properties for longer!). *Instead, the barrels blow off - late 2nd life or 3rd life... Depending upon the location & size, Contacoming cracks are allowed to be welded, using a piss-weak filler; it's a band-aid fix, most of the time. Rudi's mob (at Sale) have a much better weld repair process, but these days CASA couldn't handle extending the approval to Rotii, even if Rudi were willing to have a go (he might be?). $12k for a crankcase? Is it a hand-forged unit for a Merlin? Sand castings run about $11/kg, so the basic casting cost would be about $100; amortising the dies would be about 50 cents; machining would be a few hundred; the rest must be gouging.

You could give Howie Hughes a call - google Australian Lightwing - I believe he has some unused strut extrusion, in 6061-T6...

...but back to the thread: A small increase in overall aeroplane Clmax, resulting in a (square root of small) decrease in stall speed, is almost certainly schievable; but the scope of modifications required to get far, are likely to be horrifically large. As Dafydd points out, at this edge of the envelope, the longitudinal stability, lateral stability, handling, stall behaviour, and balked landing behaviour are all in a contest to keep the minimum speed up... The 2-seat Thrusters stall around 35~37kts, no flaps :o)