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Bruce Tuncks

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About Bruce Tuncks

  • Rank
    Well-known member
  • Birthday 08/08/1945


  • Aircraft
    jabiru sk
  • Location
    Gawler, South Australia
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  1. Is there an add-on electric oil pump? This could also be used before start-up to ensure there was no time where the bearings went dry. I have never heard of such a thing, but the idea is so obvious that it must have been used.
  2. Those vids made me feel like a wimp. Here am I at the farm where I gave up on a 550m strip to use the 1000m bitumen strip at the town.
  3. Thanks Nev, just 3 questions: 1. What temp do you remember aiming for? 2. were you using straight or multigrade oil ? 3. do you know of incidents in Australia due to this? I too have spent time waiting for the oil to warm up. And yes I wished I had cowl flaps. And I can see why engine heaters are used in cold climates.
  4. Gosh there is different stuff out there... I have read " 100 degrees F minimum oil temperature for take-off" in the Lancair stuff. I can dig out the reference if you like. I wonder why " the engine not faltering on throttle application" means that the oil is warm enough to lubricate properly.
  5. There seems to be little standardization about this. Jabiru say that the oil temp should be over 15 degrees C, while I was taught to see the needle move off the stop ( at about 50 degrees.) The Lancair with the Lycoming 360 has a much higher temp specified.n Yes its funny old units on the meter, but for sure its a lot hotter. In neither case do they have a lower allowed temperature if using a multigrade oil, but it seems that 15/50 would lubricate cold much better than straight w100. So I would lower the specified temperature for the Lycoming if using 15/50. Of course, we don't
  6. Mine was the first Jabiru kit to be supplied with an oil cooler, while an earlier plane had its builder asking for one for years. This guy was a motor-bike racing mechanic and I reckon he knew his stuff. My Jabiru ( 1998) has never had any oil-related problems, not even a leak.
  7. The finned sump was never enough. There was too-short an oil temp sensor which gave Stiffy the idea it was ok for awhile till he wised up. Fins on the inside? Has this ever been tried? I can see some drawbacks.
  8. Enlightening stuff Jerry. All good reason for Brexit I reckon. Now could be a good time to lobby over there for more sensible regulation. I reckon South Africa has better aviation regulation than the EU, and after reading your stuff, I am even more convinced that the EU has gone the nasty overly-bureaucratic and expensive way. I have seen plaintive letters from German sailplane manufacturers apologizing for charges brought on by this nastiness.
  9. There is all the difference in the world between entering cloud with a hidden mountain close by and entering a cumulus cloud based at 10,000 ft over flat land. They were in great danger, but the danger came from hitting the mountain and not from hitting the cloud. Close proximity slope soaring is dangerous enough without doing it in conditions with cloud like in the video.
  10. Here's my figures... my new prop has a 44" pitch so it would have a no-thrust forward speed of 44/(12times 6076) n-m/rev. So at 3000 rpm, the no thrust speed would be this times 3000 times 60 or 108knots. This is smaller than I expected. It means my plane can never get to 108 knots at 3000 rpm. Slowing to idle of 1000 rpm, the no-thrust speed is now 36.2 knots so a glide of faster than 36.2 knots will produce negative thrust from the prop. But the idle speed is higher when you have the windmilling effect helping the engine turn over. At 1700 rpm, the no-thrust speed is jus
  11. Regarding "negative thrust" from a rotating prop at low rpm, while I understand the theory, in practice I find this hard to see in the air or even with a model plane. It seems to me that any rpm helps a bit, and though I know this can't be so, it is what I think I observe. For some years, I crewed for my son in model-plane aerobatics competitions, and the guys there said that an idling prop was more drag than a stopped one, and they were better pilots than me. Even knowing all this, I still can't see it with the Jabiru.
  12. I agree with the idea of flying with a gliding instructor in a real glider to test this stuff out. There have been some awful crashes into flat paddocks following engine failures, and it is possible that the hitherto unknown sound of silence causes some pilots to panic. So, because Kensla is correct about some engine rpm causing more drag than a stopped prop, and Facthunter is correct about the risk of a restart failure, there is no other safe way to experience a real engine failure.
  13. My idea has been to get model plane vibration meter and wire it to an instrument like maybe a milliamp meter. This would tell me if there was more or less vibration. My senses are not reliable enough to do this alone. I would like a Balance Master but need to understand how it works. My intuition says a liquid will migrate to the outside and make things worse. Smarter guys than me say it works good, so I am still wondering where my simple ideas are wrong.
  14. Just imagine that the force of gravity was different from inertial force. We could have a much better artificial horizon and cheaper too.
  15. The correspondence between weight ( the force exerted by gravity on a mass ) and inertial change ( F=MA ) was so amazing that it led Einstein to relativity. There is NO WAY to distinguish between weight and force due to acceleration. So Einstein concluded that they were indeed the same thing and that the fabric of space-time had to be re-thought, in such a way that space and time were warped by a mass to make this so. Gosh, this is even harder than Jabiru maintenance. The Einstein thing led to different math and things like the " aberrations" of the orbit of Mercury were explain
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