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Markdun last won the day on October 15 2018

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About Markdun

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  • Birthday 11/10/1955

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  1. Markdun


  2. Nev, my apologies if you took what I said applied to you. It was actually a reference to my age. When my kids were 6 or 7 they used to think that dinosaurs were around when their grandfather was young. Now, my grandkids think the same about me. My point was that the tension between those that rely on more recent technolgy and those that rely on older methods is not new. When i was sailing in the '80s using a sextant a 'fix' was within a 5nm radius or there abouts...you adjusted your navigation accordingly....i didn't try a night passage through a gap in a reef of only 1 to 2 cables wide. ..I hove to 10nm away & waited for daybreak (to be woken by a French navy patrol boat). Others with transit satellite nav & radar went straight through (& didn't have the experience of receiving a rousing cheer & waves from the french sailors when I stumbled naked into the cockpit to investigate the noise of the patrol boat). I would sail straight through now too with GPS. I think you are wrong on GPS unreliability now. ADSB relies on GPS, as do lots of other things. If the GPS system goes down, then there are far bigger problems than a guy in a light aircraft. And even if it did, as an RAa pilot you just have to find a reasonable paddock to land. I rely on GPS for my nav in aircraft, on the sea and bushwalking. I still carry paper maps and an orienteering compass but have not had to use them for ages except to teach others or to re-assure myself that things are tickety-boo. I have two aircraft; both with an MGL Xtreme EFIS/EMS as the main instrument and with a 'steam' ASI 'back-up'. I would be happy to replace the stream ASI for a secondary electronic ASI/ALT but the value is not there to justify it. There are some inflexibilities in the MGL Xtreme, but overall they are fantastic. Cheers, Mark
  3. Ahh, Skip, its called the 'astronaut syndrome'. Back in the mid 1980's, pre-GPS & only a few dinosaurs left, quite a few sailing boat owners sucuumbed to this syndrome, with their chart table/nav desk surrounded by dials, lights and switches and transit satellite navigation, probably with a clip-board and check lists. When I was in Nukalofa I think there was only 4 of us out of 30 cruising sailors that only had a compass, log & sextant (& charts) for navigation. Much discussion then that modern sailors wouldn't know how to use a sextant if the transit satellite receiver failed etc. Seems not much has changed regarding attitudes...but tech certainly has. ....i met a guy at 1770 a couple of years ago on a very fast 50' sailing cat who had sailed from Hawaii via lots of islands with just an ipad with downloaded charts for navigation.
  4. I'm also with Skippy. ..my primary navigation instrument is the right eyeball mounted just below my forehead. After 60++ years of service with just one replacement lens I think that is pretty good. (The left eyeball, being only good for things less than 1m away without the monocle, is reserved for the instrument panel). I'm not that keen on voice alerts and warnings...one of the joys of flying is that my wife doesn't like flying and stays on the ground. ..would seem silly to have an artifical replacement that would detract from the serenity. I was taught that if I ever landed 'wheels up' in a sailplane that once the aircraft stopped, to immediately jump out and pace the distance of the landing roll....vis 'I did it intentionally to see how quickly it would pull up'. We did always fly off lawn though.
  5. I've got a real nice electric vario in my Cygnet. I do miss the lovely beep beep beep of the audio it made in a glider. I can't hear it now over the noise produced by the iron thermal (or my 'too much engine noise hearing').
  6. How many of us have lost rc gliders? Like Bruce I lost one, but about 20 years ago. Hooked it up to the bungee, let it go. ...ooops, forgot to turn the power on in the glider. ..not to worry it will just come off and land nearby.....wrong! It came off the bungee in a nice right turn straight into a thermal. I lost sight of it as it disappeared into the base of cumulus about 2500' above. No lithium batteries though, just nicads. For those wanting a 'soft start', how about a mechanical decompression lever....works ok on hand start diesels? Or compressed air, shotgun cartridge...that would be cool. I'm now getting worried about fire from my lithium batteries; i think I'll mount them in a stainless insulated box with a quick release pin attached to a servo & temp sensor so if the tempersture exceeds, say 120C, it automatically drops out of the aircraft. And if it looks like a difficult outlanding, I could manually pull the pin to jettison the battery before 'landing'. Thinking of avoiding battery started fires on crashing, how many people have a battery fuse mounted on the battery box or positive battery terminal as motor vehicles do? I also wonder how many lead acid batteries explode from the explosive mix of H2 and O2 generated when they are charging? Or structural and corrossion damage aircraft caused by the weight and acid electrolyte? I've see at least one 24 xxxx registered aircraft with cracking on the firewall from the lead acid battery mount....it was quite difficult to rectify.
  7. Mike, the stator windings melted. We removed the stator completely before another flight because we couldn't exclude a short circuit developing in the melted stator windings which could lead to more smoke & hot stuff dripping on the carbie. At 2900rpm the alternator can obviously deliver a current that exceeds the capacity of the stator windings. The starting of our diesel firefighting pump with a very tiny lipo battery also starts off slowly and as Old Koreelah said, then it cranks it with some violence. No landing lights on my planes, and my LED strobes are hardly likely to warm up the battery.
  8. Bruce, be careful with the human voltage regulator. My comment about a destroyed Jab stator comes from experience on a delivery where the Jab/Kubota regulator failed and the voltage started to creep up towards 17V (this is with a lead acid battery on my side of the firewall just near my toes). The aircraft had a nifty switch in the cockpit (Alt) that open circuited the charging wire from the regulator. So I did what you do; as soon as the voltage reached 14, I switched it off. But I also switched it back on when the voltage dropped to 12.5V (it had a big panel with old instruments)...big mistake. ...blue smoke etc at 7500' and drops of molten copper dripping on the carb (we discovered that on the ground). Skippy, the slow start is only from an early black Jabiru starter motor which is a bit underpowered. I think its just that the lithium battery doesn't deliver the current until it warms up a bit...the same as a lead acid battery...but to warm those batteries up I understand you roast them in a camp fire for 15 minutes -- well that's what I saw on the TV series Bush Mechanics. The other thing is that lithium batteries' voltage doesn't drop away as you extract energy like a lead acid battery. I'm not that fussed about it as starters are pretty robust. ..i once drove about 250m in 3rd gear in a Mazda on the starter motor across a floodway on the Nullabor when the distributor got wet. And I've seen a few times people endlessly cranking a Jabiru refusing to start (because the rpm was enough for the ignition system to fire)...This would be far tougher on the starter motor compared to the few seconds it takes to get my motor going.
  9. I assume you have installed a sliding track from a front car seat for your wing attachment so you can easily adjust your CoG. I wish I thought of that when i installed a lighter Jab engine to replace a VW, requiring moving the engine forward 50mm, new engine cowls, and then 1kg of lead in the tail because 50mm forward was too much!
  10. I just splice in an automotive blade fuse holder on one of the two wires that go from the engine's alternator to the voltage regulator, and put in a 15A fuse. These fuses are designed for vibration. I don't use the glass tube type fuses in an aircraft as the unsupported fuse wire inside the glass tube can fatigue break from vibration. The Powermate website probably has a diagram of the details.
  11. I think the big practical issue is the charging of the Lithium batteries. If you forget to turn off your master switch and find you've a flat aeroplane battery you can't just 'jump' start from your car as you will exceed the charge rate for the lithium battery (depending on the battery management system in the lithium battery). Or if you hand start, or manage to get a start from a nearly flat lithium battery, the standard Jabiru voltage regulator will also not regulate the charge current and this could see the battery's charge rate exceeded, or the Jabiru's stator destroyed (if you have no fuse in the AC side), or both. The Jabiru/Kubota voltage regulator might also have a too high upper voltage .... one of mine was at 14.4V which was a bit over the 14.0V recommended for the lithium battery. I've installed the Powermate regulator -- it regulates the charge current to a max of 8 Amps and my voltage never goes above 13.9V now. The big difference I've found in use is that on a cold morning when you press the 'start' button the starter rotates the engine to the first compression and really struggles to move it through TDC, this occurs on the second compression too, but then the battery seems to finally wake up and gets the message that it is required to deliver lots of Amperes and voila, the engine spins like crazy & starts. And it does deliver lots of Amps....I had to increase my battery fuse from 100A to 125A.
  12. Modifications to the air intake on the side of the cowl (& its position) made a big difference to EGT spread on my Bing carbed 2200. So I concur with Hyundai. I ended up settling on a port mid height (ie. widest part of cowl just under the join) about 75mm forward of the firewall. I also have a small deflector on the forward side of the hole that extends outward about 1 cm. After lots of experimentation this seemed to give the best results at cruise & WOT throttle settings. Although I have to throttle back at WOT (rpm ~ 3100 FF 23lph) to avoid exceeding 700C egt on my rear cylinders (particularly #4) at the cost of about 50rpm, & at cruise (15lph) my #4 runs at around 640 to 650C when the others are around 710-720C. No data on manifold pressure unfortunately. Why the inlet matters I don't know as I would have thought the air filter and the little rubber flap on the air filter box would remove any significant pressure effect on the carb. Carb inlet vanes made bugger all difference, except when a 'vane' obstructed one of the pressure sensing ports of the Bing. My limited experience on a Rotec carbed 2200 with a J&H filter attached directly to the inlet drawing warm cowl air with no carb heat 'a la' many Rotax 912s is totally different. EGTs are evenly spread irrespective of carb rotation. Carb temp has never been less than 30C even on a 5C OAT day, and has seen 50C+. I do worry about vapour problems as there is no float bowl in this setup.
  13. Can someone explain why a compass is still important when in most cockpits we have 3 or 4 gps devices (EFIS, handheld gps, tablet/ipad, phone) & its unlikely all will fail? If the gps system collapses there are far bigger probs afoot than landing in a paddock 'lost'. I have a 'steam powered' ASI as a back-up, but know I can fly & land the aeroplane sans all instruments. And I carry a handheld compass, but really, if all my gps went out, I'd either land as soon as possible or navigate by eye, the sun & terrain.
  14. I'm with Bruce, you should be reasonably confident flying without instruments. I did that test when gliding in NZ; we not only had to report to the CFI in the back seat every couple of minutes on our speed and altitude, we also had to do an outlanding into an unfamiliar paddock more than 10nm away from our usual strip. I was never told whether my estimates on speed & altitude were close, but I was cleared to fly cross-country. Air noise probsbly makes it easier in a glider. My primary navigation instrument is a pair of eyeballs mounted on my head. Passengers are warned that use of a mobile phone could interfear with this navigation system. Mike is correct in that assessing your speed by referencing the ground can result in stall and spinning, particularly on downwind, turning & close to the ground, but I dont think this is the case if you have the aircraft's attitude set correctly for the amount of power the engine is producing. When it comes to the engine, I am far more dependent on the gauges....I know I should be able to assess the engine on the noise & vibration, but I'm a nervous Nelly with the iron thermal up front. So I'm thinking an ipad panel connected as you suggested would be fine, as long as you are confident you can fly the plane if it goes pear shaped. But I would suggest you think about engine monitoring too. We just need someone to make something like the MGL RDAC with wifi connectivity. FWIW, on my panel I have one MGL Xtreme EFIS/EMS & a mechanical ASI with legacy fuel flow, compass and electric vario/vsi (from pre Xtreme time), & I have a handheld GPS & an Android tablet sort of running OzRunways. I also take my little Silva orienteering compass & paper WAC....I have used that compass for steering across oceans (in a boat) with legs exceeding a thousand nm in pre-gps days...probably unecessary now.
  15. I am no battery expert, but ALL lithium batteries have lithium ions and can be referred to as lithium ion batteries. All (or nearly all) lithium batteries on the market have porous carbon anodes. Lithium iron phospate batteries are one type of lithium ion batteries, where the cathode is made of compound containing lithium ions; there are others, eg. Lithium cobalt oxide, lithium titanate etc. My understanding is that the term "lithium ion' is used to distinguish these types of batteries from early lithium batteries that had metallic lithium in the cathode....and these batteries had a particularly high fire risk because during recharging you would get dendrites of metallic lithium growing on the cathode and these dendrites could reach the anode, resulting in a short circuit and thermal runaway leading to a fire. This is not to say other lithium batteries are immune to fire. And of course lead acid batteries can also develop internal shorts from lead dendrites (but no thermal runaway). Have a look at this site for more info Lithium-ion Batteries Information - Battery University I would suggest that SSB are correct in referring to their batteries as both lithium iron phosphate and lithium ion. What would be good is if the battery manufacturers published the detailed specs of the battery management systems so we can compare. Skippy, you may want to check Lithiumax batteries....similar price to SSB, and they are advertised as suitable for aircraft. I have both and I can't really tell any difference but the vibe I get is that the BMS on the Lithiumax could be better...but that is just a guess in the absence of specifications and measurement.
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