Jump to content

pluessy

Members
 View Profile  See their activity

  • Posts

    130

  • Joined

  • Last visited

 Content Type 

Everything posted by pluessy

  1. pluessy
    I have just re-installed OZrunways after 3 years and I'm not impressed. It has become so complicated that it is now a destraction while flying. I can't download just the maps I need (Qld) and it is clogging up my iPad memory. Flight plans are the little squiggly line bottom right (in map mode). Then give it a name and find your departure & destination (ICAO code). They seem to save automatically. With the new version, it becomes a fight with your finger to enter the waypoints correctly. I'll be looking at alternate options once this subscription expires. I have contacted OZrunways and told them that it is too complicated for RAAus weekend flyers and to give us a simpler version (best one is from about 3-4 years ago), but got brushed off.
  2. pluessy
    you forget the difference between DIRECT drive (aircraft) and the postie bike. Check the postie bike power at 3,000rpm!!! Rev the aircraft engine up to 6,000rpm and you will get over 250hp, but not for long. Same for fuel burn: aircooled engines have to use fuel for internal cooling due to the large bores. The weeny little bike piston ccan be cooled by the barrel. You are comparing apples with macademia nuts🙃
  3. pluessy
    Fuel burn on the 80hp is around 14lph at 75% (91 octane), the 100hp uses around 18-19lph, but minimum 95 octane (premium). Here in OZ that makes a big difference in fuel price (UL95 is ~$.15 and UL98 ~$0.20 more than UL91). Many European countries have much smaller differences and some don't even produce UL91 any more.
  4. pluessy
    I would recommend to remove the strut brackets, strip the paint and crack test them. This looks like cracking has started at the gussets: For the chute cover, make a new plywood sheet, seal it with thinned epoxy and add some foam to the underside with 1 layer of G40 glass. The cover needs to be able to be blown off easily when activating the chute.
  5. pluessy
    Using a sharp pointed pitot or a very thin-wall tube will reduce the effects of AoA and sideslipping on the ASI. Most commercial pitot probes have a very pointy end (conical) to reduce the flow disturbance at angles.
  6. pluessy
    Warning! Warning! If your engine turns the same way as the 912 (CW looking from behind, then the advise so far is correct. If your engine is turning CCW, then the offset needs to be to the left.
  7. pluessy
    some 1st hand experience from today! My mower had some water in the fuel and stopped. I drained the fuel tank and the float bowl, flushed the line and added some metho and clean fuel. The engine wouldn't start unless I covered the carb intake with my hand, then it would run for a few seconds. I had to repeat that for a couple of minutes before the engine would run normally. Bottom line: water in a carb means dead-stick landing, no matter what!
  8. pluessy
    you will find that the surface tension of water will stop it from going through the main jet without significant differential pressure (more than the venturi can provide). Water in a carby is usually a dead-stop until removed by draining/cleaning.
  9. pluessy
    I have one of these jump-starters, have used it a few times now on V-twin mowers. Would start a Jab or Rotax engine as well. https://www.jaycar.com.au/450a-li-po-jump-starter-and-powerbank/p/MB3757 The unit is just under 0.5kg.
  10. pluessy
    I would check other manufacturers data that make wooden props. Main criteria is bolt size and some times hub thickness. Wood type could also have some influence: From Culver props (left) and Catto (right):
  11. pluessy
    some on ebay: this one seems to be 006 to 016 in 002 increments: https://www.ebay.com.au/itm/264092846959?epid=2295842872&hash=item3d7d290b6f:g:X6AAAOSwubRfoxxz&amdata=enc%3AAQAHAAAAwJv5UrkQn98de5bchTVWZNfEwmMXCu0KOylz6vCToVdj6Y6krrUi4x5AbGC1ookaLWl6crNapl%2BT4OsAV9XPkk3n6tLHtWnjsdTZ15FUaXAkjYo49HOsXVbDKAAxyY0VXJRrwlKpJ9Nioy3%2BSHHbXY58m1hXIcav4XbLVS5EhGwwhxQg5zt8Msc1frL4vL6tsWtmdJRPltYf7NpYNoJdUq59HC3PGSZQVjUVkJH%2BfQjVfBL%2BwR%2FiTOyteMVJ8XyJlw%3D%3D|tkp%3ABk9SR4y8qI_oYQ this is a full set, 0.05-1.00mm in 0.05mm steps: https://www.ebay.com.au/itm/155393994522?hash=item242e342f1a:g:QaIAAOSwMthj32NR&amdata=enc%3AAQAHAAAAwHqtnRRWgt4WvHiNEfCed%2BjRc7At7LfGwuwGzceT3DLOOx66Erlzqw6n3yOpieenIfrqHEE%2Bb8LY%2BC6mmb3o2lqJ2GG0jozTHeqB6UYZl1pfppv3V1dLW9tdg4s5ymwA9Qhk%2BBTJyPBoxRJAHO0BIcK54svlyARf88c5mtwBAxi8SIAbG%2BTpAs0Kna8k7pvk3k%2BEI6WPkxejzoKD7HBYkLJ3xlDQuMZUb4IkfTwgWdsrCVaBUexJhHuiPhYWSt%2B3Ig%3D%3D|tkp%3ABk9SR86QrY_oYQ
  12. pluessy
    Look for the equivalent filter from Donaldson or Fleetguard. I consider Ryco to be a cheap filter, Donaldson & Fleetguard are used by major OEMs in the mining industry. They also publish their filter specs.
  13. pluessy
    What about your fuel pressure? Is that now staying in the normal range?
  14. pluessy
    no need, the #35 (0.35mm) jet has been documented by Rotax and mentioned a few times in this thread.
  15. pluessy
    That 3lph is correct for 0.4bar fuel pressure and reduces proportionally with lower fuel pressure. In flight at 4,800 and higher rpm, I do have 0.4bar. At lower rpms, it can be less, at WOT in climb (5,300rpm), it is just below 0.4bar. I did have a few episodes where the fuel pressure fluctuated a bit in cruise. It is usually happening with fuel level at the lower end and possibly short unporting of the pickup. My Tecnam has wide but shallow tanks with no internal baffles, so fuel sloshing around will unport the pickup at low levels. I deliberately ran the LH tank (with fuel return) dry once to see when I run out and what happens. I picked it up on the fuel pressure, watching it slowly dropping to 0 and then switched tanks before the engine stumbled.
  16. pluessy
    I used the fuel flow gauge, engine off, electric pump on and running it for 10-15min to get a stable reading. Then I used that to re-calibrate the fuel flow meter so it reads correctly at full fuel pressure. I have suggested to JP Instruments to add a calibration routine to the FS-450 so that the instrument can compensate for the return fuel and show true fuel flow.
  17. pluessy
    Not confused. The 3lph of fuel return are insignificant compared to the 18-26lph that go to the carbys. The carbys will overflow if the fuel pressure exceeds the float force. With the engine shut down and temps increasing, the fuel pressure will increase and over-power the float force (fuel pump valve prevents venting backwards) if there is no return line vent. The longer the fuel lines, the more fuel it will force into the carb bowls. Reading a pressure gauge is not just the value, it is also the way the needle moves (fast/slow/steady etc). I have been flying behind a 912 for over 500h and do my own maintenance, so know a thing or two. The return orifice is not required for flying, just makes starting easier and helps with extended ground taxiing times (low fuel flow to the carbys and high under-cowl temps).
  18. pluessy
    Correct, 0.35mm will give you ~3lph fuel return at the normal fuel pressure. Pre-startup check: when you test the electric fuel pump, watch the pressure climb slowly and settle at the electric fuel pump pressure (depends on fuel pump) turn the elelctric pump off and watch the pressure slowly decrease (it decreases to 0 over 5+ seconds) -> orifice is clean This orifice does nothing in flight, you have 7-9lph flowing to each carby and the 3lph of the return line is just change. The purpose of this orifice is to purge vapour and air prior to start, with the electric pump. It will help a bit on decent with low fuel burn but then you also have low power (heat) under the cowl, minimising the vapour problem. The fuel lines should be fire-proofed so they are not going to heat up the fuel by much in flight. Heat comes from the fuel pump, gascolator (not insulated) and any other exposed fitting or gadget. After shut-down, the temp of the fuel will increase and the orifice will prevent a build-up of pressure and overflowing of the carbys. The downside is that the 0 pressure will encourage vapour formation. Go back to pre-startup check point "check electric fuel pump"🙂
  19. pluessy
    I invested $800 in a pair of precription sunglasses (brown tint, 1.5-2.0 reading insert at the bottom, slight correction for straight ahead) a few years ago and I wear them all the time (driving, flying and outside). It is expensive but is worth every cent. Beats having a small pair of reading glasses on the tip of the nose and a normal set of sunglasses behind. Most electronic displays are more difficult (or impossible) to read with polarised lenses. Polarised are great on the water and in the snow. I tried a set of small binoculars but they are pretty much a waste of time. As passenger, having a large pair and being able to concentrate might be ok. Using binoculars as PIC means you are becoming focussed (tunnel vision!) on looking for your target and will forget to fly.
  20. pluessy
    If you have an air bubble in the top part of the cooler, there will be no heat transfer happening there. To flush this bubble out can be tricky. I haven't had any problems yet when changing the hoses but I don't run the engine unless I had good pressure while cranking with the plugs out. If there is a large volume of air flushed out while running, you could lose oil pressure while the engine is under load.
  21. pluessy
    FYI, Tecnam (on the P92 Eaglet at least) is mounting the oil cooler up-side-down eg the oil cooler ports at the bottom. It takes a bit more priming after the 5-yearly hose change to remove all air from the suction line & oil cooler. I always crank it with the top spark plugs removed until I have positive pressure for at least 10s.
  22. pluessy
    If you add the water after the carburetor or throttle, keep in mind that the high vacuum at low idle will suck the water up from about 5m below. You might need a solenoid or use a peristaltic pump (cheap off eBay). Proper water/methanol injectors have a minimum pressure valve as part of the injector body that only opens when the supply pressure exceeds a certain limit. Methanol is added for a number of reasons already mentioned (anti-freeze, power) but also to prevent algae growth in the bottle and lines. Especially important if any lines or the reservoir are open to light.
  23. pluessy
    I have that problem, but more with safety glasses and hearing protection. When flying for extended times, it becomes a nuisance and requires the sunglasses (arms) to be moved up off the ears to ease the pressure.
  24. pluessy
    Eliminate the source of the spike where possible and replace coil relays/solenoids with solid-state versions.
  25. pluessy
    I also crank the engine with one set of spark plugs removed (caps grounded or ignition off) until I have positive oil pressure on the gauge. This way the engine (and starter) has no load and you can crank it for 10-15 seconds without overheating the starter motor or the engine firing up and running without oil pressure. Standard practice for every rebuilt engine and should be done on the Rotax whenever the oil lines have been opened. Burping the engine before draining the oil is also standard practice. If you don't understand the oil system on the 912, read the manual. The way Rotax designed the dry-sump system for the 912 is quite different (unique) to most conventional oil systems, dry or wet sump.
×
×
  • Create New...