3rd harmonic

Nice work on the AEG batteries and welding helmet it helps keeps the MONEYBOX full rather than empty😉!! It's the kind of stuff I do likewise.. I've got an 6Ah AEG battery that a mate gave me which unfortunately got flooded overnight when it rained (when it did actually rain some years ago) the cells are fine but the multi layer BMS PCB suffered electrolytic corrosion and is buggered! High temperatures are a fairly big deal for LiMnCO2 or LiFePO4 batteries, the BMS will often just disconnect the pack for safety. They especially DO NOT like being charged while hot, as that generates more heat internally - much better to let the batteries cool down before wacking them on charge. Yeah, those 12v LiFePO4 batteries are great for caravans/campers ect but a serious stand alone power system with a 24v or 48v bank is better resolved by using individual 3.2v block cells with separate BMS and cell balancing system (I was a CEC accredited designer of solar off grid stand alone power systems for a while)

Some understanding of contemporary 3-stage lead-acid battery charging might help: 1. Bulk stage: (constant current) the charger pushes the voltage higher at the max current it can source (or is selected) 5, 10, 20A ect 2 Absorb stage: (constant voltage) when the voltage gets to 14.2-14.5v, rather than pumping out max amps to push the voltage higher, the charger holds the battery voltage constant. The current into the battery should taper off as the charge is absorbed though ALL the material on the plates. 3. Float or maintenance stage: (constant voltage) generally after a perset time at the Absorb level the charger will drop the voltage back to around 13.2-13.8v, the current into the battery should be pretty low at this point. Any additional load across the battery can then be supplied by the charger while the battery is 'floating'. For lead acid batteries temperature strongly affects the charging end point voltages and this needs to be compensated for - correct charging of larger battery banks in fixed installations generally always has a temp sensor on the cells. Especially for batteries that are not used all the time, it is IMPERATIVE that they are charged to the absorb level regularly to avoid the plates becoming 'suphated' ---- To answer the question, a bench supply or an RV power supply will just float the battery and supply any load with master switch on which will work fine, although without any absorb stage. The regulators on traditional aircraft alternators are pretty low tech, generally they only float charge at no more than 13.8v and there isn't any basic temperature compensation that most automotive ones have featured since the 1980s. This tends to result in undercharging, suphation and early battery failure.

Those RV wall power supplies are much like a 13.8V bench supply with some current limiting at maybe 20-40A. But a 13.8v bench supply would be fine anyway, you ain't going to get 60A flowing even if can do it... Essentially, if the battery is in a reasonable state of charge at 12.5V, even 0.25ohm on a 1-2m of your connection cable to the battery which could be 8-10 AWG will limit the current into the battery by (13.8-12.5)/0.25 = 5.2A It will gulp abit of current initially, after some minutes it will push the battery volts up to the float level (13.8v) and the draw will be minimal, plus whatever is turned on in the plane.

Yeah, his engines are bloody awesome! That graph I picked out compares the Edge performance 915 to a standard 912ULS. If you look elsewhere in his photos the Edge performance version of a standard 912, but injected, has a flat 130NM torque curve from 3700rpm upwards and is good for an extra 10-12hp. Because the motor breathing is so much better and the fueling is more consistent it uses a fair amount less L/hr for the same hp.

If you follow the EDGE PERFORMANCE FB feed, he often puts up VERY interesting dyno graphs of the engines he's produced or overhauled. These are ACTUAL measured results, not theoretical speculation. This one is particularly instructive, for the 912ULS the TORQUE curve is in reality pretty much flat above 4700RPM, HP increases are really due to increasing RPM. Over proping the engine with too coarse a pitch, will tend to 'slug' the engine, much like changing into a higher gear on a (manual) car at too lower a speed. It definitely not going to cause any damage because the engine can't do any more than the available torque at that rpm, but the horsepower developed will be down on what would otherwise be possible. I experienced this directly in the VH Sports-star with a CS prop, on one circuit when i forgot to set the prop rpm up to max, which as i recall was 5800rpm corresponding to 'full fine' pitch. We were still climbing away OK, but i was indeed 'slugging' the engine at about 4800rpm! Once that was pointed out, a quick flick of the dial allowed the motor to really scream at full noise and the performance change was quite noticeable...

That list of items that are considered 'Line Maintenance' is pretty extensive and most of the items listed there could easily get you into big trouble and/or damage the aircraft if you didn't know what you were doing. I think they make some passing comment about people being competent to perform the task, but who decides that? Some people who might quite competent or experienced pilots, wouldn't know the difference between a left or right handed screwdriver! I would back my engineering/mechanical skills over my piloting skills every time, but that's just down to lack of experience in the latter. In a different life would love to have been a flight engineer - on those big complicated aircraft they are REALLY the ones in control 😉

Yes, the park brakes were lock-wired down/off in the sporty's I flew which were used for instruction, i assume to avoid the chance of landing with the brakes on - probably a good idea with low time students. The inflight adjustable prop looks like a nice simple system to operate, assuming it's setup well and you keep an eye on the RPM. You'll have to let us know how it how goes when you (finally) do get it in the air!

What CS adjustable prop do you have? I've have a fair amount of flying in the sporty's which are heap of fun. The RaAus 24 registered ones at Aldinga had a standard 912uls with a fixed pitch woodcomp prop. But at one point they were booked up /out of action so I had a go in a VH registered one that has a 915 turbo with CS adjustable prop. I was instructed not to use full power because it really wasn't nessecesary (it wasn't), then on one circuit we did wind it out to full wack. The motor was SCREAMING and we were going like a cut snake up at a very steep angle! Definitely it would be cheaper in your own aircraft, so that seems like a good plan...

Yep, definitely no owner maintenance for hire/reward and in the RAAus context that would be mainly flight training aircraft which can be hired out for solo time. I think that's fair enough actually, the expectation rightly should be that aircraft used to carry/train members of the public are maintained by professionals at arms length and not modified from the factory spec.

The 19 reg aircraft that I am trying to fix up has wings that can be removed for transport/storage. To remove or reattach them legitimately and sign that off you have to be an L1. Like moneybox I have a lot of engineering experience and skills but had never worked on an aircraft at that stage. So I went through the process, enrolled in the online course did lot of reading of the FAA reference material and maintenance rules and passed the exam. The pass mark is high and some of the questions were pretty obtuse, but managed to get it done. I did that some time after I got my RaAus licence. I stand to be corrected but I think that 24 reg factory build aircraft have to be maintained by an L2 / LAME or they lose the factory built status.

This accident has to qualify as one of the most brutal EVER! Obviously, there was decision making process (or lack there of) that led to the A/C ending up where it did. Happen to be watching ABCnews24 and they had live footage from a BBC reporter showing the accident scene this morning. The concrete slabs on top of the dirt mound which the localised antenna structure were mounted looked to be at least 0.6m thick by several meters square. Maybe there should be concrete slabs at the end of every runway, that would focus the mind of pilots so they are on-speed and on-point OR decide to go-around early? Crying out loud...

Yeah, it was sadly mentioned on this site previously that Ray was no longer with us. When I visited him at Camden there was A LOT of aircraft in various states of repair. I was hoping that thier might be a garage sale of the stuff as I was looking for some Morgan related items, I'm sure it wouldn't be so easy to deal with tidying that all up...

Adelaide really SHOULD have a rail link to the airport, it's only a relatively short distance of a few of km's from the main rail corridor at Mile end which is a fairly short distance to the CBD, in contrast to Melbourne which is a very looong way away. In my mind this seems like low hanging fruit! The the south rd upgrade using tunnel boring machines is going to cost mega bucks, but rail hasn't rated a mention...

Most of these permanent magnet alternators which are found on motorcycles and aero engine are a shunt type regulator. Essentially the control element 'shunts' current to ground to hold the voltage down as the output increases with RPM. A capacitor is a good idea on the output as this will tend to bypass any switching noise or spikes to ground, rather than relying on the battery which may not be effective. However large electrolytic's offen have a fairly low self-resonant frequency that may be only a 400-500Hz, above which the capacitor is behaves like an inductor. To ensure the capacitor remains capacitive a 1uf polypropylene film cap can be used to bypass the electrolytics.... A large filter capacitor means the alternator can effectively run the electrical loads without a battery connected.

Adelaide biplanes will definitely let you hire & fly solo once endorsed. Under RAAus, the tailwheel endorsement is competency based, essentially you keep practicing and learning until they are happy that you can handle the aircraft in a variety of conditions, then they sign off your log book. I would say that Aldinga can be pretty windy and changeable at times which does give you exposure to conditions that aren't straight forward and that does help challenge the skills. If you look at the Adelaide biplanes FB page just last month they sent a 16 Y/O solo in the champ and a 18 Y/O gained pilot certificate (tail-wheel) which is pretty awesome. The pricing is online: https://adelaidebiplanes.com.au/pricing/