IBob
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Everything posted by IBob
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Partial glimpses here taken during build, when I was trying to figure out why my exhaust pipe wanted to occupy the same space as the cylinder coolant plumbing..............:
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Hi Marty, the Sav has a bracket from the gearbox side bolts to shock mounts to the oil cooler top. This is a fabricated bracket that picks up the side bolts and has a crossmember across the top of the cooler. The bottom of the oil cooler is shock mounted to a bracket made in the same way that goes back to side bolts under the engine. That point also serves as the mounting point for the top of the coolant radiator, which is also shock mounted. The rear of that radiator is pulled up to the underside of the engine by a tie. I'm sorry I don't have a clearer pic.
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The popular 1930s (?) book, The Professional, is intended as a humorous address... but also contains all the solid practical advice you'd ever need to site and construct a longdrop. Or a row of them (the family 3-seater etc). As this is what the book is all about. Factors when siting included putting it out past the woodstack: since the ladies don't like to announce where they are actually going, they can say they are just going out to get some wood. and that way the woodbox always stays well topped up. Clearly you missed the opportunity there, Marty......but you may still find you are required to add soundproofing....)
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It grew rockets???????????????????
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OME I have ridden to 13'000ft over Florida in Mr Douglas, a DC3 with tinted windows, 8 track stereo...and yes, shag-pile carpet (though I can't vouch for the fire rating). Where we all got out.......well, all of us except the pilot. The jump itself was a shambles: we all had green cyalumes taped to our rigs, but nobody had thought to equip the base (centre jumper of the proposed formation) with something of a different colour. So the sky was full of little green lights, all wandering around trying to figure where to aim themselves, before finally heading off for an empty bit of sky. But I wouldn't have missed it for worlds.......)
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Despite the carpet in my kit being precut, fitting it wasn't the pleasure I thought it would be. I was using Ados F2 contact adhesive from the can on the hull, and from spray cans on the carpet. I'm a fairly tidy worker, but it was messy, with overspray finding it's way onto me, the floor, and anything in the vicinity of the spray area. It had the usual contact adhesive problem that you only got one shot at positioning the carpet piece. And I went through 2 cans of spray with only half the job done. For the second half, I hit on a better system: I thinned the can of F2. This allowed me to spread it on both hull and carpet with a brush, slowed the drying time, and allowed the piece to be peeled and repositioned if not properly placed. This was a huge improvement. The bond is not as strong as using straight F2, but is more than adequate for attaching carpet: 3 years on, nothing has come loose. For thinning I used what was to hand at the time: 2 way paint thinners. The fumes were awful, fortunately I have a good spray mask. I now see that Ados do a Solvent N for thinning and cleaning. In the next life I'll be using that......
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Your Mk1 version works fine here, Mark. I think the key thing is that the inner latching works need to be be completely free moving and free of any possibility of binding.
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A simpler option (certainly when building) would be to remodel the bracket to tilt the stick forward a bit. It would mean moving the pivot point a bit forward and adjusting the sweep and position of the quandrants to ensure correct mixer movement, so would mean making new brackets. But it shouldn't be hard to sort out.* The reason I like that option, and the reason I stuck with just modifying the stick Is that, apart from stick angle, the mechanism is simple, safe and works very well. The innards do need to move freely, almost rattly loose, as the latch mechanism relies on the spring under the button. So the usual thing when setting flaps is to give the stick a wiggle to make sure it is solidly latched. I have also seen situation where the rubber grip has moved up on the handle and is starting to foul the button, so the grip needs to be well anchored. *Maybe a little job for Mark..........in his spare time.....😆
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Shafs, I'm of average height, so seat fairly far forward, and I found pulling full flaps on the standard lever very clumsy: instead of pulling up on the handle, the last notch was pulling back into the stomach. That and incident reports where improperly latched flaps have caused a few frights and sometimes major damage, and I decided I needed to do something about it. It took a while to decide on how to do the internals, but turned out to be very simple, just needs to be made fairly precisely. I had help with the fabrication, my DIY abilities come nowhere near welding stainless. The angle in the shaft is just 12degrees, but for me it has made a huge difference. PS note also Mark's excellent 3 position flap bracket in place of the standard issue 2.
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Looking really nice, Mark!
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And here is a the A/B/C pinout: https://duckduckgo.com/?t=ffab&q=pinout+of+rotax+oil+pressure+sender&atb=v356-1&iax=images&ia=images&iai=http%3A%2F%2Frepairguide.autozone.com%2Fznetrgs%2Frepair_guide_content%2Fen_us%2Fimages%2F0996b43f%2F80%2F20%2F27%2F4c%2Fmedium%2F0996b43f8020274c.gif
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Okay, so I found this, which suggests that they are using a 2 wire current loop setup: https://duckduckgo.com/?t=ffab&q=pinout+of+rotax+oil+pressure+sender&atb=v356-1&iax=images&ia=images&iai=https%3A%2F%2Fdesk.zoho.com%2FDocsDisplay%3FzgId%3D714941653%26mode%3Dinline%26blockId%3D1hflqdbff7005142a40f9ac47410e66c421a2 It says that Pin A = n/a Pin B = 8-24VDC (12V in our case) Pin C = Signal And here is how it is wired to the gauge: https://duckduckgo.com/?t=ffab&q=pinout+of+rotax+oil+pressure+sender&atb=v356-1&iax=images&ia=images&iai=http%3A%2F%2Fwww.aviasport.com%2Fimages%2FConexiones_OIL_P_4_20_57.gif Danny, I found that by searching 'pinout of rotax oil pressure sender'.
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Agreed, Nev: if buying from a transducer manufacturer or supplier, it would all be on the data sheets. But Rotax have gone to their own numbered part (albeit manufactured by others) so unless we have a non-Rotax part number for the unit, we're guessing a bit. Unless Rotax have published details somewhere.....they may have.
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Danny, as I recall, my engine came with the sensor/sender (we just used to call them transducers) fitted, with the plug and cable attached. The cable would have been marked, so no need to meter through to the plug pinout. If all else fails, maybe you could find someone with a new uninstalled engine, and get them to meter out the cable/plug for you.
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That's correct, Skippy. Think of it as a diaphragm, with one side to atmosphere, the other to oil (or fuel) and it is measuring the deflection in the diaphragm. The key element is that oil pressure is atmospheric + pump pressure, so you are measuring that against atmospheric pressure. So as you climb, the atmospheric pressure should decrease on both sides of the diaphragm, but the differential pressure (and diaphragm deflection) remains the same = accurate reading. If, however, the atmospheric pressure falls as you climb on the oil/fuel side, but remains at ground level pressure on the other side (due to being sealed) then you get an increasingly inaccurate result.
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Danny, these sensors are differential: they should measure the difference between the oil (or fuel) pressure on one side, and atmospheric pressure on the other. Your oil pressure is atmospheric pressure + pump pressure, and is measured against atmospheric pressure. So as you climb, the atmospheric pressure falls, but the differential pressure remains the same, so you continue to get an accurate reading. But If the sensor is sealed on the atmosphere side, then the atmospheric pressure is falling as you climb on the oil pressure side, but remains the same on the 'atmosphere' side. So you get an increasingly inaccurate reading. And in the case of Skippy's fuel pressure reading it would make a huge difference.
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Ah right, Skippy, that would be much more of an issue: the oil pressure unit is 0 to 10bar, mine sits 5 to 6, but the fuel pressure is 1/3bar or less, so if the unit is not correcting for altitude, you would see little or no fuel pressure at 10,000'. I have seen the same problem now, twice, with fuel pressure steam gauges, where the builder has not removed the shipping plug from the gauge body.
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That's an interesting one, Skippy. Given that 10,000ft sees approx 30% drop in air pressure, if altitude is the problem you would see approx 1/3 bar error at that height...not much, given that my oil pressure normally sits over 5bar.
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Nev, could you explain about the rings not bedding in and so burning more oil? I'm not disputing this, I would like to understand it better. Thanks.
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Hi Pat, it looks as though they made all the required changes to turn the Classic into a VG, as per ICP factory designs. Perhaps this was necessary for certification. I don't think that has much to do with removing the slats and adding VGs, though my understanding is that ICP made a small change to the wing leading edge profile when they took that step. An excellent source of information would be John Gilpin at Stolspeed: https://www.stolspeed.com/slats-v-s-vgs
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It is what's called a current loop device, they commonly come in 2 and 3 wire versions and are an industry standard. Instead of behaving like a variable resistor, it puts out a current between 4 and 20mA. This one has a span of 10bar, so 0bar = 4mA and 10bar = 20mA. The 3 wires are 0V and 12V to power it, and the third wire is the 4-20mA signal. The reason for using current as a signal is that it can be connect with a short or a very long wire and it makes no difference. Voltage, on the other hand, will drop with a longer connection, due to the resistance of the wire, giving an inaccurate reading. However, the reason for the change in these Rotax sensors was that the old VDO sensors had an unacceptable failure rate.
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Hi Pat. Lots of good Savannah info here. And no shortage of opinions, either! Not sure why removal of slats would require structural reinforcement, will be interested to hear what you find out.
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Note that if you have steam gauges, you cannot connect this newer type of sensor to the older style VDO gauge. The correct steam gauge is this one: https://www.aircraftspruce.com/catalog/inpages/cps15-06649.php?clickkey=64183
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I pulled my windscreen back too tight at the top centre, Mark, with the result that it dented in there far too easily. The fix was just to let it out...a surprisingly small amount, like about 2-3mm at the centre, progressively less towards the sides...which then gave it a curved 'brow' and the right shape to withstand the prop blast. Fortunately, there was enough material there to do that......
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BrenDan I did part of my training in Technam P2002s, they had a centre throttle and one on the left side. (I flew on the left, but tended to use the centre throttle, as it was next to the trim switch, though trim may have moved to stick top buttons now. Then I built, during which I flew very little, and had to swap hands once the Savannah was finished.) So you may find Technams out there with a LH throttle, maybe make a few calls?
