Dafydd Llewellyn

Take a good look at the wing root fillets on a Spitfire. It had the highest limiting Mach No. of any WW2 fighter

Once passed a gaggle of pelicans at 8000 feet over Tenterfield, happily thermalling with yard-long grins on their faces. Don't assume any soaring bird will be at low level.

Try http://www.alfatest.com.au/

Yes, it is bloody complicated; that is largely a consequence of two things: Firstly, we are still in the middle of a complete re-write of our legislation, to bring it into some sort of alignment with the rest of the World; and there are too many cooks involved. New Zealand made a far better job of it. Secondly, we have had a policy, since 1985, of automatic acceptance of overseas aircraft certification, at least from a defined set of "recognised countries". That, plus the need to accommodate what had gone before, is what has caused such a plethora of different categories in CAO 95.55; when the FAA introduced "Primary category", we had to bring in parallel legislation to enable us to accept American primary category aircraft. Similarly, when the FAA introduced LSA category, we had to add that to our legislation. We already had CAO 95.10, CAO 95.25, CAO 101.28 and CAO 101.55 aircraft; and then the European manufacturers started exporting stuff that was none of the above, so that had to be added, too. We gained an experimental category as the end result of decades of lobbying by SAAA, AOPA and others - so CAO 95.55 got -19 class also. By contrast, apart from FAR Part 103 - which is fairly much equivalent to CAO 95.10 - the FAA does NOT accept anything unless it gets an FAA Type certificate; and everything gets an N-number registration, and it ALL operates under FAR Part 91, and you need a standard pilot licence to fly ANYTHING. Yes, it's simpler to understand - but there's no scope for anything like the RAA, GFA, HGFA, etc. Do you really want that sort of simplification? On the whole, I suspect we'll have to go that way to tidy-up the current mess - but it would mean scrapping a lot of existing aircraft, and a lot of recreational pilots would have to get an RPL in a hurry. The alternative is to do enough study to understand what we currently have.

I agree entirely with Oscar; I've spent a professional lifetime ensuring that aircraft designs comply with relevant safety standards - that's what Type Certification is all about. The safety standards are, in the main, international, but empowered by Federal legislation (See CASR 23 thru 35). I find it irritating beyond measure that this effort is largely beyond the comprehension of the legal profession. It also annoys me extremely that the ADRs for motor vehicles are declared to be Product Safety Standards for the purposes of the Trade Practices Act, but aircraft certification standards are not. There is a vast inconsistency between the law and the factuality of compliance with prescribed standards. It is this inconsistency that is driving our manufacturing industries backwards. An aircraft manufacturer spend millions to get his product fully developed and certificated, and what does this gain him? The right to be the target of litigation. Think about it.

Quite right. We've been amusing ourselves hypothesizing about a possible next step beyond the current CAMIT engine. The sort of mod. needed to do all this to an existing Jabiru installation as a minimum-cost change to an existing aircraft, may well be impractical; we won't know one way or the other without a lot of experimentation, to see what can be done without radical alteration to the engine installation. We also don't know whether the benefits would justify the cost. But it's entertaining to look for a glimmer of pie in the sky, at least in a forum such as this. Call it brainstorming. Returning to what is practical here and now, the current CAMIT engine is essentially a greatly-improved drop-in replacement for the original engine, and it has to fit within the same constraints - so the sort of idealistic answers we've been discussing may not be feasible; any improvement in mixture distribution - if indeed one were really necessary - may have to come from an EFI approach, because perhaps that's all that would fit. However, burning a little more fuel than the theoretical optimum - probably a little less than for an original Jab. engine, tho this is yet to be seen - will allow it to achieve the reliability and durability targets with the existing carburettor; so that's the first step; and it's a big one. That will get the aircraft flying the way they were originally intended to; further refinements - if any - must wait to be developed and proven. It's taken Ian Bent a decade to do the research for the existing CAMIT engine; let's be realistic. This does not mean we should stop at that point; the discussion has been about what options might be worth further research. However, it would unquestionably be pursuing diminishing returns. One can develop a product for ever, but it does not necessarily make economic sense to do so. The requirement for carburettor air preheat is a temperature rise of 50 C minimum in the air entering the carburettor. Normally one gets about half that from the heat coming off the engine cooling fins, and the other half from an exhaust muff. The amount of heat needed to do that would be around five kilowatts, I'd guess. At least an order of magnitude more than the alternator output. Electric preheaters are a bad joke.

True - that's one of the real advantages of a multi-point FI system. But you still require an alternate air source with some pre-heat - see FAR 23. The practical difference between the MFI and the carbie only becomes noticable if the outside air temp is below 15 C. Above that, no carbie heat is necessary. A "smart" closed-loop carbie heat system would supply only that amount of heat actually required, whereas the normal manual setup must supply at least 50C temperature rise upstream of the carbie. If the outside temp is below -5C, no carbie heat is required. So one does not need to heat the carbie all the time.

Thanks, Nev - this is the sort of thing I meant, when I said that we have not pursued the CD carburettor far enough as yet, to justify dropping it. We need to delve into these sorts of options; what has been done so far is to take the least-cost option - one carbie - and fiddle with the manifold to get it to work after a fashion. We need to go one better. I'll shortly be trying a single Bing 64 carbie on a 582, with a heated Y-branch manifold; the carbie will be mounted under the engine, not on the engine, and I'll have provision to adjust the aim from side to side to balance the mixture distribution. This requires that the elastic centre of the engine mount system is at the powerplant centre of gravity, otherwise the motion will likely be too much for the rubber connections at either end of the manifold to accommodate; but it will greatly reduce the vibration level to which the carbie is subjected. If this works, it could provide some data for a multi-cylinder adaption. If one wanted to adapt such a setup to provide some detonation protection, it would be not too difficult to use a standard knock-sensor plus EGT to switch a small solenoid valve to slightly alter the pressure above the fuel in the carbie bowl, to richen the mixture somewhat. Again, this needs a test bench. One could arrange the setup so it failed rich, which would greatly simplify approval. It needs some smarts, to prevent the system from hunting; a PID controller may be necessary. However the hardware is all off-the-shelf, and not stupidly costly. If anything needs to be closed-loop automated with a carburettor setup, it is the use of induction air preheat to keep the induction air temp above the icing range (i.e. above around 15C); the manual carbie heat control would be the reversion option. I'm not against such applications, provided each one of them is independent and can be made to fail - safe - that way, the system will not stop the noise - and it will be vastly easier to trouble-shoot.

A propos of the latest release about the manoeuvres of the aircraft, does it occur to none of the ratbag journalists that if you get an oxygen fire in the cockpit - shades of Apollo 1 - not only will the flight crew lose consciousness in seconds, but there will very likely be uncommanded inputs into the autopilot as the various cockpit switches etc are in the process of being destroyed? An excursion to 45000 feet would surely kill everybody on board, and after that it's the aircraft's natural stability and the yaw damper flying the thing, plus whatever overrides may be there from the ground proximity system, rad alt etc. The inertial platform will be close to the aircraft CG, so it would continue to supply attitude data, one would assume.

Flow straightening can't fix the up & down movement of the fuel spray stream with varying butterfly position; it can affect the side - to- side distribution. The vertical movement would probably have minimal effect if the carbie fed no more than two cylinders, and the manifold divider was vertical. One might need to take advantage of the flexible carbie mounting to adjust the side-to-side balance, but once set, it should stay OK over a range of throttle settings - if the flow is de-swirled. All this is hypothetical; it needs testing on a bench. I may be able to do that later this year. If it works, then using two carburettors for a four cylinder engine should allow a considerable improvement in mixture distribution. With a single carbie, on a four cylinder engine, part of the problem is almost certainly the form of the intake end of the induction manifold. Presumably, if the outlets are arranged in stacked pairs for a four-cylinder engine, the vertical movement due to butterfly position will bias the mixture distribution between the upper and lower pairs of outlets. Offhand, I cannot visualise a form of fixed-geometry flow divider that would correct that; however perhaps one could put an adjustable vane - somewhat in the nature of a second butterfly, moving in reverse to the throttle butterfly - in the passage between the carbie and the manifold; this would introduce an additional icing problem (though maybe not much worse than for the butterfly - for which the existing carbie hot-air system is sufficient). Experimentation needed; it may be possible to simply gear it to the main butterfly. This would require an STC approval for any certificated engine. The other question is, just how important is a small split in EGT? I suspect 25 degrees C is not worth chasing, or that one could realistically expect to do much better, unless you have a full closed-loop feedback setup for each cylinder - and no automotive EFI that I've come across goes to that length.

Thank you for the clarification.

Yep. I'll be happy with a CAMIT engine with a CD carbie.

The Sting case was not, in fact, focussed on the engine. Its focus can more correctly be judged by the attention CASA has been giving to the RAA registration of aircraft at invalid MTOW.

Diesels, with basic mechanical injection systems. If somebody could only build one that's affordable, and light enough, and does not need to be blown to 3 atmospheres to get a reasonable power to weight . . . There's no simple best way. A chaque un, son gout.

That's far from the whole story of the Sting case.

My point was that insurance is NOT the total answer to liability, and I don't give a damn what kind of liability you're talking about.

I suggest you look at Division 5 of http://www.austlii.edu.au/au/legis/nsw/consol_act/cla2002161/ - and see whether there is parallel legislation in other States. This Act and the precedents referred-to were the reason that the Sting case was settled, despite strong evidence of both negligence and fraud. I don't consider this justice. The provisions in the NSW Act were introduced because insurance was either not available or not practical for a number of common recreational activities. This is obvious for activities such as bungee-jumping; but it was not so obviously applicable to activities such as flying training in a type-certificated recreational aeroplane or to gliding, prior to these precedents. I suggest you will find similar legislation in all States & territories. I do not know to what extent the precedents may be applicable outside NSW; no doubt that will be tested in the courts in due course. I am far from suggesting that this situation should be taken as a carte blanche to be reckless; or to ignore a normal duty of care, but it does offer the glimmerings of some relief from the otherwise almost impossible situation of organisations like RAA and FTFs. To what extent CASA's recent volte face on the subject of the SMS reflects the implications of these precedents, is an interesting question, I think.

No; professional liability insurance became unavailable to CAR 35 engineers around 2001 or thereabouts. The QLD Professional Engineers registration Act had to be revised as a consequence. The practical effect of insurance is that it makes one an attractive target. The ONLY effective defence is to be not worth sueing. Is this a recipe for a developing society? I don't think so.

Yes, indeed - and that's how it has been done, in GA; the pilot has a manual mixture control; the carby or multi-point mechanical fuel-injection system is set up to give the correct result (on quality-controlled fuel) at standard sea-level conditions, and the pilot is supposed to use his brain to adjust the mixture at altitude. The carburettors and MFI systems are tightly controlled as to who is allowed to fiddle with them. The pilots get some training as to what the mixture knob is there for; but flying-training schools mainly tell the trainees to leave the mixture full rich, because that saves engines in basic circuit training, so it's debatable whether it is driven sufficiently firmly into some pilot's skulls. Given an EGT and CHT on every cylinder, and proper knowledge of what they mean and how to use the mixture control, this system works very well; but there are still engines being wrecked in GA due to finger trouble, especially now fuel price is seen as a major part of the direct operating cost - so this approach is not perfect, either. However, scratch almost any experienced ex-GA pilot and I wager you'll find he'll prefer to have a manual mixture control. The RAA scene is rather different; firstly, the available engines all use CD carbies and do not have a mixture control - so pilots are not trained to use one, unless they come from a GA background, which may or may not have driven the knowledge into them successfully. Secondly, the maintenance requirements for RAA aircraft do nothing to control the knowledge and competence of people who want to fiddle with their engines. Why did the engine manufacturers choose to make it impossible to train RAA pilots about the use of mixture controls? (One guess). If I were an engine manufacturer in this environment, I'd make the same choice; product liability really leaves no other option. Multi-point mechanical fuel injection - provided everything is working as it should - improves the mixture distribution; and it lessens the induction icing problem (tho not as completely as people generally imagine; an alternate source of warm air is still required). However, there are more things to go wrong in even the stone-axe mechanical systems used in contacomings, than in the carburettors they replace; and I've seen some truly bizarre engine failure modes from them - the Continental "rich-cut" mode is one that few pilots comprehend, and it beats me how it ever got past certification. So the "educated operator" approach has large holes in it, too. On the whole, I consider the adoption of the CD carburettor to be one of the choices that has made recreational aviation possible, and I think it should be recognised as such. No, they're not perfect - and there are still some shortcomings in our knowledge of how to best use them, such as de-swirling the air entering them, and how to design a really effective way to distribute the fuel spray. But I suspect they're the least-worst option; and we need to be just a bit smarter in how they are applied.

Let me see if I have this right . . . this most erudite debate began from a discussion of how to increase the engine reliability by reducing mixture mal-distribution, which causes uneven cylinder temperatures, and can provoke detonation, etc, didn't it? And it wandered off into the by-ways of being able to contend with off-spec fuel, improve overall fuel consumption, etc, which are by-products of an EFI system ? IF that's so - and I've always been of the view that the top three criteria out of ten for an aero engine were, in order, reliability, reliability, and reliability . . . then should we not consider the causes of unreliability? We always tend to jump to a "New" solution before we finish getting the bugs out of the old system. This has never made total sense to me; but it seems to be a fundamental human behaviour. One of the main arguments in favour of a fuel injection system over a carburettor, is that most people do not feel competent to tamper with a FI system, whereas anybody who has owned a lawnmower feels competent to muck about with a carburettor. So should we go to mechanical and electronic complexity as a means of reducing finger-trouble? This is sane? The same reason applies to the use of constant-depression carbies; they are, to a degree (roughly 50% by my figuring, but it can be better than that, depending on the needle profiling) inherently altitude-compensated, so the manufacturer can leave out a mixture control that the pilot can abuse - at least, for the density altitude range allowed for RAA aircraft. Also, the richening that occurs despite the CD carbie's inherent compensation, provides a mite of extra cooling as the air gets thinner. That's not all bad. That's where we are right now; the biggest cause of engine unreliability - at least, in the view of the manufacturers - is finger trouble. BMW were talking about sealing the bonnets of their cars at one time, I seem to recall. The "No user-serviceable parts inside" syndrome suggests there is more than a little validity in this point of view - at least, until the warranty runs out. If you look at a Marvel-Schebler (now Facet) carburettor from a Lyconental, you will find a damn near bullet-proof device of almost aggressively basic simplicity; but it requires competence on the part of the pilot. That's one way to achieve reliability - use the KISS principle. It's worked pretty well, for around sixty years, but it's not idiot-resistant. Getting rid of the mixture control by using CD carburettors is a further step in this direction; it gets the pilot's digit out of the equation, at the cost of adding the potential unreliability of the rubber diaphragm. Further, nobody, but NOBODY, is allowed to strip a GA aircraft carbie except a licenced carburettor overhaul shop. Over-regulation? No, I don't really think so. It's about the only practical way to control the hazard from finger-trouble. What causes mixture mal-distribution from a CD carburettor? We could do with some intelligent research into this. However, several aspects are known: Firstly, the fuel spray moves up and down as it enters the manifold, according to the butterfly position. If you only feed two cylinders per carburettor, and the dividing edge in the manifold is vertical, and the carburettor is installed accurately horizontal, this need not cause a mal-distribution between the cylinders. However, this will only be true if there is no swirl in the airflow as it exits from the carburettor. Swirl can be (usually is) introduced in the airbox upstream of the carburettor; and it can be largely removed by flow-straighteners in the duct between the airbox and the carbie. How many installations have this feature? Ian McPhee drew it to my attention for a Jabiru installation in a Motorfalke; I've not seen it used anywhere else. It made a huge difference in that installation. Feeding more than two cylinders from one carburettor poses much greater difficulty. Rotax uses two CD carbies on its 912 - but is the dividing edge at the start of the manifold vertical? If not, I think they missed a point in the design. I take the view there is scope for further improvement in the way we use carburettors; and aircraft engines do not have to meet the pollution constraints over the enormous range of operating conditions of a car engine, so the full scope of EFI is not necessary to get an aircraft engine to market. The common perception that "it's gotta be EFI" is, I think, somewhat short-sighted - but it may be forced onto the engine manufacturers by popular (but pig-headed) perception, whether or not that is the best answer.

Try https://www.google.com.au/search?q=echin+V+STGC&oq=echin+V+STGC&aqs=chrome..69i57.11640j0j7&sourceid=chrome&es_sm=93&ie=UTF-8

AMEN! The media reporting is almost farcical. Anybody who has read the story of the finding of HMAS Sydney - not all that far from the search area for MH370, but in about half the water depth, will have a good idea of what is going on. Obviously neither our media "experts" not Tony Abbott have read it.

Does anybody know whether the MGL V6 VHF COM transceiver has been accepted by the powers that be in Australia?

What of the precedents set by NSW DC 11 - Noel Campbell V Rodney Victor Hay and Echin Vs STCGC ?

Are you sure of your facts? The operating limitations of VH experimental are stated on the experimental certificate, and they can vary according to what the aircraft is: From CASA AC 21.10: 17. OPERATING CONDITIONS AND LIMITATIONS 17.1 Conditions, limitations and directions for operation of an aircraft on special CoA are entered in the Annex to the certificate. They should be designed to fit the specific purpose(s) and situations that apply to the aircraft. The operating conditions, limitations and directions that may be prescribed, in accordance with the applicability chart at Appendix B of this AC, are listed at Appendix C of this AC. CASA or the authorised person may impose any additional conditions, limitations or directions as deemed necessary in the interests of safety of other airspace users, and persons on the ground or water. The CASA officer or the authorised person should review each operating condition, limitation or direction imposed, with the applicant, to ensure that they are fully understood by the applicant. And from Appendix C of that AC: (19) No person shall operate this aircraft unless within the preceding 12 calendar months, it has had a condition inspection performed in accordance with the CASRs/CARs, or other approved programs, and found to be in a condition for safe operation. (20) Only CASA licensed or certificated persons with appropriate ratings as authorised by the Civil Aviation Regulations may perform inspections required by these operating limitations. (21) Inspections shall be recorded in the aircraft maintenance records showing the following or a similarly worded statement: “I certify that this aircraft has been inspected on………….. (insert date) in accordance with the scope and details of ……………………………….., (insert identification of the approved maintenance program) and found to be in a condition for safe operation”. The entry will include the aircraft total time-in-service, the name, signature, and certificate type and number of the person performing the inspection. (24) Application must be made to CASA or an authorised person for any revision to these operating limitations. (25) The pilot-in-command of this aircraft should notify air traffic control of the experimental nature of this aircraft when operating under Instrument Flight Rules (IFR), and shall request routing that will avoid built-up areas of cities and towns, and congested airways, if possible. Air traffic control approval to fly over a built up area of a city or town does not constitute approval under CAR 262AP (5).