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Markdun

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Markdun last won the day on February 12 2013

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About Markdun

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  • Birthday 10/11/1955

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  1. Markdun

    SSB Lithium Iron batteries

    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.
  2. Markdun

    SSB Lithium Iron batteries

    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.
  3. Markdun

    SSB Lithium Iron batteries

    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.
  4. Markdun

    SSB Lithium Iron batteries

    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!
  5. Markdun

    SSB Lithium Iron batteries

    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.
  6. Markdun

    SSB Lithium Iron batteries

    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.
  7. 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.
  8. 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.
  9. Would love to. Waiting for the changes from CASA that will enable us to install a cheap version easily. I have an AIS marine transponder in my yacht (simliar to ADSB but without the ground stations/satellite links &;a lot slower). Its great...ships 'see' you, and if they don't you can ring an alarm in the bridge through their vhf radio. I did see an official marine rescue vessel once going 15kts sternwards from the AIS...they had made some installation error.
  10. Just to be different I like to use the area frequency. My airstrip is about 5nm south of Lake Bathurst and Canberra controlled airspace LL is at 6500'. I have 3 other airstrips within 2nm of mine; one is commonly active with gyros. Also I'm directly on the flight path for military aircraft going backwards and forwards from Canberra to the secret airbase Albatross at Nowra, and many of their helicopters and fixed wing aircraft fly at around 1000'agl or below.....my normal circuit height. On a couple of ocassions listening in to the class G area frequency (which is actually Canberra Approach east) I have heard vhf aircraft circling at 4500 waiting for clearance into Canberra, and a quick call to the ATC has enabled us to maintain better seperation. I find listening in to the appropriate area frequency gives me better situational awareness, including on cross country flights and it also makes it easy to terminate or extend Sarwatch. However, the military is another beast. I have had to take evasive action to avoid a blackhawk when I was on downwind. I have emailed them about this but have not even had a reply...no idea what frequency they were on. I even suggested they could land at my place for a coffee so we can better arrange how avoid each other. I thought the old concept of ALAs was ditched many years ago when the rules changed to require pilots to make a decision whether they could land/take-off from a location and that ALAs are now only relevant because some insurance company's will only cover the plane if it is operating from an ALA???
  11. 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.
  12. Markdun

    SSB Lithium Iron batteries

    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.
  13. Markdun

    SSB Lithium Iron batteries

    Bruce, the 'bluesmoke meltdown' was in a friend's plane I was delivering. It had a rather large and very heavy lead battery with the original Jabiru/Kubota voltage regulator. There was no fuse in either the AC side of the regulator nor the DC side. (And I might add, despite being previously VH registered there is no main battery fuse either) The aircraft had both an ammeter and voltmeter and a toggle switch that could open circuit the DC side of the alternator (ie. you could switch off battery charging). In my familiarisation flights I found the voltage was creeping up to 16V as indicated on an anologue gauge (auto quality). The aircraft had a good avionics panel, transponder artificial horizon, turn & bank etc..almost IFR, but no glass EFIS/EMS. Being worried about damaging the electronics & the battery I thought it wise to turn off the charging whenever the voltage increased to 16V and to turn it back on when the voltage dropped to below 12.5V. Not a big task as the battery was huge...maybe it needed about 5 minutes every hour. However, I have subsequently read a Jabiru advisory that it is possible to exceed the current capacity of the alternator at high rpm with a voltage regulator failure and a battery that will absorb a heavy charge current. Their advice on noticing a regulator failure is to isolate the charging circuit and land and replace the regulator. The approach we have now taken is to install the Powermate regulator which should limit the voltage to 14.2 and current to 8A and to install a 15A auto fuse on the AC side of the regulator (plus a lot of re-wiring as well). This means if the regulator fails, at most you are up for the cost of a new regulator plus a 50c fuse, and not have to contemplate rewinding the jab stator or buying a new one for $500. And more importantly you will not get molten copper dripping onto your carburettor. This is all a bit off topic though. My understanding is that the lithium batteries like the SSB are able to deliver heaps of current for little voltage drop, and so can crank an engine really well, right up to the point of total discharge. However, the electronic battery management system does not tolerate high charging currents...so if you do substantially discharge one, you can damage it by charging with a standard lead acid battery charger/regulator and particularly by 'jumper' connecting it to a charged lead battery or running car's battery. I'm no expert in this, but this is what the battery suppliers say. I think my Lithiumax 400 battery has a maximum charge current of 8A, but it easily delivers 60A plus to crank the Jabbie 2200...real fast. So the one downside of the Lithium batteries are no jump starting.
  14. Markdun

    SSB Lithium Iron batteries

    I'm not sure that problem is limited to lithium batteries. ...plenty of cases of melted alternator windings and escaping blue smoke (blue smoke is the thing that makes all electronics work) from Jabs with lead batteries. I'm now a firm believer in having a fuse/circuit bre a ker in the AC side of the Jab alternator after experiencing blue smoke in the cockpit and then a subsequent ground inspection showing molten copper dripping around the carb...with a lead battery - & the failure was the voltage regulator, not the battery, nor the alternator.
  15. Markdun

    SSB Lithium Iron batteries

    I've had one in my Jab powered aeroplane for 2 years. It weighs almost nothing. Still going well. Really cranks the engine fast even on minus 5C days. I did put in a Powermate regulator because of a negative voltage spike isdue that resulted in weird fuel flow numbers on my EFIS/EMS based on advice from the EFIS people who said they had a few issues with Jab regulators. Previously the bus voltage at cruise settled at 14.2V but now it's 13.7V. I can't tell the difference other than reading the voltage numbers onnthe EFIS. All works well.
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