Dafydd Llewellyn

That's news to me; what brand has that? Must be a glider instrument; normal sensitive altimeters get sufficient vibration from the engine. Gliders normally uses a variometer (fast-response rate-of-climb), with total-energy compensation, to detect thermals.

That's how it's arranged - see photos . The installation is complicated by the fact that the panel you see here is shock-mounted behind a fascia in the aircraft that is structural; so the ipad tray has to be mounted on a stand-off from an existing instrument hole, such that when it's in the aircraft it stands about 6 mm proud of the fascia. As you can see, it is really a squeeze to accommodate it in the panel. In view of the upper temp limit of 35C, I may have to reverse the arrangement I intended and blow cold air onto the back of the ipad from what it shown as the outlet; and that supply may need to run through an insulated container holding a freezer brick. Glider cockpits can get very hot on the ground, so the ipad goes into the tray as the occupants climb aboard; but the cabin air temp may be too high to provide any useful cooling at low altitude. The lid of the tray is not shown in those pictures, but it opens to act as a shade hood. The 12 V charger I have is Bauhn 2.1 amp device; it seems to be the same Belkin charger, re-branded by ALDI, as Apple were recommending at the time. It's a cigarette lighter socket type, which I dislike, but I could not find anything more apposite at that time; maybe there's something better now (suggestions gratefully received). I'll be using a filter network to minimise the spikes going into it; the engine is a 582, and it's across a lead-acid battery. The ipad is a basic 16 Gb series one Ipad mini, and I use a BadElf Pro bluetooth GPS. The only application will be Ozrunways.

What I get from this, is stick to lead-acid for the main aircraft battery; and where you have a low-power device such as an Ipad mini, it needs to be (i) in the shade, (ii) supplied with cooling air - and that may mean air that has been run past a freezer brick - and (iii) I'm going to put a temperature sensor on the back of the thing and see whether Don Ramsay's notion is correct.

Thanks, Don - that's an interesting slant on it, and it makes sense. I wonder whether there are others with experience on these aspects?

Ta - That's what I understood. I've installed my Ipad mini in a stainless-steel tray, mounted on the instrument panel, with a stainless-steel cover that opens to act as a shade hood, or closes to contain fumes etc. The tray has an air-extraction tube (1/2 inch bore) that draws cabin air past the back of the Ipad & dumps it overboard, to cool the thing and remove fumes. Hopefully, that will serve in the event the Ipad gets hot & bothered, but I've no way to assess its adequacy.

I had a problem - or at least a potential problem - with using the Jabiru ignition switch leads as a source of RPM data for an MGL Infinity E-3 instrument; the E-3 manual tells one to use 10 K ohm resistors in the leads, but the oscilloscope still showed spikes (well over 50 volt) at the far end, which I decided I could do without. A small ferrite-ring core with about 50 turns of wire, short-circuited, simply thread the RPM sense lead through it, and the spikes were reduced by about a factor of ten. No maths, just grab an existing small ferrite ring choke, short circuit the ends of the windings, and it works. No doubt one could be more scientific, but . . .

So where do we stand with an Ipad mini (Li polymer battery)? Obviously one should not charge it in flight; and it needs to be kept out of direct sunlight; but if one does those things, what's the risk?

I suspect the trick is to do something that gets the fathers in, too. Something like offering a scholarship to fifteen year olds, to solo standard. The fathers come along to satisfy themselves that it's a properly-conducted exercise, and of course you take them up to demonstrate . . .

Whilst CAO 95.55 exempts RAA aircraft from CAR 157, and therefore from the legal requirement to fly above 500 ft except when actually landing or taking off, or in a designated low flying area, I would have thought teaching people to fly orbits below 500 ft instead of going around would be pretty irresponsible.

Well, ask Jabiru for a release note for it, stating that it's suitable for your engine. They shouldn't have any difficulty with that.

If you make a mod. like that to a certificated engine in a certificated aircraft, without going through a formal approval process, it's a criminal offence in GA (CASR 21.183 and S20AA.3 of the Civil Aviation Act) carrying a 2 - year gaol sentence. So not exactly a laughing matter. I don't know what the situation is for an RAA registered aircraft, but I suspect S 20AA would still apply. The engine has to have its crankshaft torsional oscillatory stress investigated during the type certification process; so if you change something that would make the original test invalid, the approval process requires a re-run of the test. Altering the ignition advance will affect the crankshaft torsional oscillatory stress.

No, still wrestling with instrumentation and other gremlins. The engine I'm currently running is a solid-lifter 2200, with some but not all the CAMit mods. I doubt I'll get an opportunity to look at an hydraulic-lifter or roller-follower engine; Ian is concentrating on solid lifter engines (of course, he has a conversion kit to convert a hydraulic lifter engine back to solid lifters.) What I'm seeing so far is mainly to do with the pressure drop from above the barrels to below them, and the head temperatures that result - and at present I can only get to 27 inches manifold pressure (I'm at 2000 ft AMSL here) and 2800 RPM with the available propeller. The engine in the cell has the old coarse-pitch fins, so not representative of the later "microgroove" fin heads. The engine has under-cylinder baffling, so that's different from a typical aircraft installation, too. I had a lot of trouble getting the oil temperature up into its correct range, because in the test cell, the engine is uncowled, with the cylinders supplied from a blower, and the whole of the sump is exposed to the full propeller blast; I had to insulate it to get proper circulation through the oil cooler, which allowed me to get the oil temp under control. So the test cell is still in its teething stages and the data so far aren't sufficiently general or proven for me to start making pronouncements. However it looks to me, from what I've seen so far, that it would be preferable to locate the oil pressure sender on the main oil gallery downstream of the oil filter and oil cooler; and also to locate the oil temperature sender on the return side of the oil cooler. The engine limits would need to change to reflect these locations; but Ian's mods to the oil pressure relief valve have resulted in the test engine holding its oil pressure very well. I've installed a large Roots supercharger on the cell, driven by a 5 HP 3-phase motor, and I'll be running a test on the supercharger lubrication system this afternoon, if that works, I should be able to get sea level conditions this weekend. However indications are that the cooling blower needs modification to its intake and blading to supply sufficient air for full throttle running; with the old heads, I don't want to exceed 180 C (calibrated).

I think it comes down to this: If the head bolts show no evidence of losing tension, and the valve clearances (on a solid-lifter engine) do not keep closing, then the operation of the engine is staying within safe parameters. If this is not the case, the engine is operating at too high a temperature for the materials from which is is built. There are also various conditions, as have been mentioned on this thread, that can aggravate to situation, especially leaky valves. Unfortunately, one cannot use the valve clearances as an indicator on other than solid-lifter engines. However, checking these things regularly is a useful means of verifying that one's operating procedures are OK, and this is a far better indication than anything the gauges may show. I agree that it should not be necessary to keep doing this, but it seems to be necessary for Jabiru engines; they do not have much margin in hand. The same principle applies to the through bolt tensions. If nothing's changing, it's OK; if things are changing, it's not likely to run to full life, unless you alter your operating procedures to stop things from moving. Whether it is possible to operate the engine so that the head-bolt tensions etc do not change, depends upon the adequacy of the installation of the cooling system, and on the mixture not being too lean; these engines have (like any air-cooled aero engine) to run well on the rich side above about 75% power. I am not addressing questions of workmanship here; but people should perhaps be aware that there appears to be some evidence that there can be a difference in reliability between engines that have been modified subsequently to their original assembly by CAMit, and those that have not. CAMit was once building over four hundred engines per month; but that led to an overstocking of engines by Jabiru; and some of those overstocked engines may have been modified to later build standard, not necessarily always by CAMit.

Unless that modification has been verified to cause no adverse effect on the crankshaft torsional stress - which involves strain-gauging the nose of the crankshaft - I'd be very wary of it. Especially on a 3300. That's a mod that can have - I don't say it does, but it can - have very dangerous side effects. One of the fatal RV crashes I looked at was caused by a blade failure of a Hartzell propeller, only about 275 hours from new, due to vibrational stresses induced by a non-certificated replacement of one of the magnetos by an electronic system that gave more ignition advance than the engine had been cleared for. The vendors of such a system are very likely at risk of culpable negligence unless they have done the necessary testing on the engine to clear this point.

I'm curious to know a little more about this "usual troubles starting my Jab." I've been starting one in an engine test cell without difficulty, using a very ordinary automotive 50 AH battery at the end of about twelve feet of lead on both the positive and the negative side. However, the Jab. starter draws sufficient current to blow a 100 amp fuse (as I discovered by blowing one), so the cables need to be quite large to avoid excessive voltage drop; I'm using heavy welding cables. If you refer to Chapter 11 of FAA Advisory Circular 43.13-1, you can find the resistance of typical aircraft cables. With an average current of 100 amps, a circuit resistance of 0.01 ohm will cost you one volt at the starter, so going up a size on the cables is likely to make a considerable difference. So is a poor connection between the cable inner and the end lugs.

The reason for this is, I suggest, to be found in S8.2© of the Civil Aviation Act 1988: 8 Establishment of CASA (1) An authority called the Civil Aviation Safety Authority is established by this subsection. (2) CASA: (a) is a body corporate with perpetual succession; (b) shall have a seal; and © may sue and be sued in its corporate name.

No, I haven't, because I very seldom travel by airline. Where is EU? Where is dubia? And where do you find the flight times? Any hub-and-spoke airline system always entails stupid amounts of sitting around; there was an excuse for that in the days of F-27s, which needed water/methanol, but the Dash 8s etc do not need this, so it's well past time the airlines got more useful. No, I'm NOT better off flying out of Brisbane, because there's nearly five hours driving in that, for a round trip, plus the exorbitant Brisbane parking costs. I am not defending the airline services - I think they stink. But I WAS contradicting your comment that there were no airlines servicing Toowoomba.

Well, not to those centres perhaps. However, see http://www.qantas.com.au/travel/airlines/flights-to-wellcamp/economy/global/en

You can't turn history back; but it's important to understand why we are in the current situation; the litigious society is mainly responsible - and it's a product of the concept that anything that happens is always somebody else's fault and/or the Gummint orter fix it. Protecting consumers from unscrupulous manufacturers has been a major focus for the last four decades; but the consumers remain largely ignorant of the fact that the job of doing this has been placed on the manufacturers, because they are in a position to extract the cost from their customers - i.e. the consumer get protection, whether he wants it or not; and the consumer pays for it, plus the underwriters' profit, plus the lawyers' profit - whether he wants to or not. I think it's about time the emphasis shifted a bit, to protecting the consumers from thermselves.

Yep. Why do you think Cessna put so much effort into the C208? And most other manufacturers stopped offering singles altogether? The product liability insurance cost for a 172 isn't that much less costly for a 208, so it's a much larger proportion of the selling price. The litigious society shot itself in the foot.

The big difference is the product liability insurance.

Re catching the Kids' interest, I've been wondering (on the odd occasion I've been driving somewhere, in lieu of listening to the radio) whether there would be any merit in carting the dead Blanik I purchased for spares, along to the local primary school, and maybe showing the kids a video; I've noticed at places like the Paris air show, that there's no substitute for a piece of real hardware that people can walk around (and touch, if there's an attendant there to stop them pinching bits). You forget pictures as soon as you walk to the next exhibit, but you remember hardware, if it grabs you. My wife, who was a schoolteacher, thinks this would be a waste of time and effort; but I notice a lot of aeronautical engineering uni courses are now building kit aircraft as part of the coursework.

I guess it's a question, not of average income, but of disposable income; and that generally makes recreational aviation a "grey power" activity. It's also a question of one's priorities for that disposable income. If one has been bitten by the aviation bug, it's high on your list of priorities; but it seems less people are being infected nowadays. Flying airline in a widebody jet does not cause people to be bitten by the bug - more likely, repelled. Your fellow who gives free rides is far more likely to generate interest - but his targets are people who are already at the field anyway. So the question comes down to what has happened to the "kid on the airfield fence"? - and the answer is, he's playing computer games. He doesn't have a pushbike, because his parents know it's too dangerous in to-day's traffic; and the airport's too far away to walk, and it's a lot easier to turn on the computer. TV made personal flying something "they" do, not something normal people do. A small minority get bored with computer games later in life, and discover that "they" is actually "we", but a fair number of them get turned off by aircraft that are not as good as they appear, too costly to maintain, etc; and the category rules set by the relevant authorities don't do much to fix that. Gliding used to be a "self-help" activity that was readily affordable, and one found all sorts of people involved, from all walks of life. It tended to take a full day to get just one flight; but that didn't matter if you were an integral part of the club activity. However, that "simply messing about in aircraft" hard-core style faded out as people started to want a turn-key activity that they could walk up to, fly, and walk away. So gliding became an elitist sport. Grass-roots ultralighting took over, but it has also gone away from the "minimum cost fun" activity. This seems to be a general pattern; I watched it with small sail boats, it started with the VJ class, with cotton sails, and developed from there. These things seem to have a "half life" of about 20 years; then they split into one or more minor groups that stay with their particular activity, e.g. Gyros or Trikes, whilst the majority move to something else. I don't yet see what the something else will be for the present bulk of RAA, but the overall pattern is there, just the same. People seem to fall into two classes as far as aviation is concerned - there is a majority, who drift into it for a year or two, and then drift out again, to try skiing or whatever; and a small minority, for whom it is a lifetime activity. The "casual" participants aren't prepared to put in the effort it takes to get more than a superficial involvement; the "serious" ones find it a subject that one can never finish learning about, and get enormous satisfaction from it. If you gave your kids a hammer when they were four or so, rather than a TV set, they are more likely to develop an interest in aviation; but not all kids are interested in making things.

Door opening is pretty common in low wing cabin aircraft due to the pressure differential between the cabin and the flow over the wing (the low pressure field extends over the top of the fuselage to a considerable extent.) The suction means you can't close the door in flight. I've had it in a Bonanza and a Cherokee. Main thing is, don't over-react and do something silly; it's NOT an emergency, just a nuisance. You do tend to lose flight paperwork. Not common in high-wing aircraft, because the pressure differential is a lot less. Where it's dangerous, or potentially so, is in an aircraft that has an upward-opening canopy; loss of the canopy can make some aircraft uncontrollable - especially if it takes the fin off as it goes.

You have to have a reference thermometer, and a block of high thermal conductivity material to which you can attach both the active end of the thermocouple and the reference sensor. The least expensive form of reference thermometer is mercury-in-glass; see attached. However these are fragile and awkward to use. They need a large block, bored sufficiently deeply to allow the thermometer to be entered to its specified immersion depth, and the use of a "coupling fluid" to help transfer heat to the thermometer; and because of the slow heat transfer to the thermometer, the heating rate needs to be low. The results I posted were obtained this way, with a heating rate of around 2 degree C per minute. A more convenient form would be a hand-held meter; however it needs to be a type that uses either a platinum resistance thermometer or has cold junction compensation, if it uses a thermocouple. Either of these features make such a reference thermometer much more expensive; FLUKE make a good one - it's around $aus 1700. http://www.testequipmentdepot.com/fluke-calibration/thermometer-readouts/1523.htm