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Bruce Tuncks

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Everything posted by Bruce Tuncks

  1. Bruce Tuncks
    Thanks guys! I will send a pic of what i"m talking about soon, together with measurements for RF guy. Once I read that 1/4 inch diameter tube had the same drag as a Libelle wing .... wow.
  2. Bruce Tuncks
    I don't like the vent pipe on my Jabiru, especially the enlarged bit at the top which looks like a casting and it contains the forward-facing vent holes. If this top bit were sawn off and the pipe given a low-drag shape, a lot of drag would be saved, plus a bit of weight. The effective height of the vent would be reduced a bit , by the amount of the cast bits, which are about 30mm I think. Has anybody done some drag-reduction work on these?
  3. Bruce Tuncks
    My only real spin entry was in a Ventus in Nevada. I was taking a photo of a snow-topped mountain and framing the picture with the rudder while looking through the camera at the clear-vision panel. Bugger, thought I. My old Mosquito back home would never have entered a spin. But at 17,000 ft, ( 12,000 agl, the sagebush plains are at 5000 ft.) in a strong glider, there was no fear. I did get scared at Tocumwal on the base-to -finals turn in a short-wing Lancair. The plane was strong enough but there would not have been enough height to recover. And there was not much wing holding us up. Any training should therefore focus on spin prevention, not spin recovery.
  4. Bruce Tuncks
    Quite right KG. The only purpose of writing in code is to cloud the message. Yes, the code may have served a purpose in the days of teletypes, but those days have long gone. Once I said to myself GAGOY ( get a grip on yourself ) and BAM ( be a man ) and JLUTFG ( just look up the f.... glossary ) only to find the second acronym was not even in the glossary! Two things are obvious... 1. The exercise is for the protection of bureaucrats. This has been noticed already. 2. Don't have an accident! They might get you anyway, but it helps not to compound the issue.
  5. Bruce Tuncks
    In the books defence, I have to say that the loose jam nuts bit was just the first chapter. Actually, I do recommend a read, but I doubt that expert guys like you lot will learn much new stuff.
  6. Bruce Tuncks
    Was that Bribie island you meant Space? I have the distinction of capsizing a sailboat in Pumice Passage which is near there. In 4kts wind.... that took some serious bad sailing.
  7. Bruce Tuncks
    You could also die from being too conservative... such as by landing straight ahead when there were no good options.
  8. Bruce Tuncks
    Nev, I read that RPT had lots more checking than GA. So the real mechanic could make a mistake, but it would be found out. In fact some places had more time spent checking than the workers who did the jobs. What do you reckon? It sure would be expensive to check so much.
  9. Bruce Tuncks
    Yep onetrack, I have read that the main difference between GA and RPT servicing is along the lines you wrote of.
  10. Bruce Tuncks
    The book explains about jam nuts often being left loose. These are the locking nuts on pushrods etc. I agree with onetrack in that I have never heard of loose ones causing an accident. But I am going to have another look anyway. One thing that was said was that an average plane had at least 3 things wrong.... wow, I hope mine is better than that.
  11. Bruce Tuncks
    In this particular school, they taught their students to touch the control as they went through their checks. Prior to this crash, I thought that was a good idea.
  12. Bruce Tuncks
    There was a crash in SA a few years ago where the student SHUT the fuel while checking it was "on". They finished in a vineyard and the instructor did well to land it parallel to the wires. They both survived well.
  13. Bruce Tuncks
    I wonder if the second book is necessary?
  14. Bruce Tuncks
    thanks yenn I actually bought the cheaper book " Are your nuts tight?" and found it quite good, although the pics were of much worse things than I have ever seen.
  15. Bruce Tuncks
    Thanks onetrack. I bought the cheaper one on pdf and it was about 60 dollars, which is just ok for me. The first book is still over 120 dollars! Anyway, it was good to get the version I could read right away. Thanks again.
  16. Bruce Tuncks
    Vertical Speed Indication is necessary to thermal a glider. It needs to be compensated so that " stick lift" doesn't show as climb. I never found much use for it with power, except for when I was ( unsuccessfully ) trying to thermal the Jabiru. But the VSI is not compensated on the Jabiru, so this may have been the cause. On my model planes, the absence of compensation is a real problem. This was unexpected to me.
  17. Bruce Tuncks
    There are 2 new books I'd like to read..." Are your nuts tight ?" and " Pre-buy" by Vic Syracuse. Ideally, I would like to download these to read on the computer, but this is probably asking too much. Any ideas?
  18. Bruce Tuncks
    We used to do this at my club with gliders. A flight with the ASI and Altimeter covered up. The instructor, sitting behind, had his instruments clear of course. As Nev says,they generally flew about 5 knots faster, which I reckon is the correct thing to do. I never expected to do this for real, until one day I did a test flight for this guy who had connected his asi wrongly after an annual service. The slower you flew, the higher was the asi reading. There were no problems , and we didn't use the altimeter much anyway because it is useless when landing out. I reckon I flew the circuit about 10 knots faster than usual. We had an old ww2 strip which was more than long enough and the Mosquito had wonderful flap-brakes. There is nothing in the RAAus training like this, and I appreciate that the tandem seating of a glider makes it much easier to do than the side-by-side of a Jabiru, where you only have one asi. If I were to lose the asi on a Jabiru, I reckon it would be similar but harder than with a glider because of the absence of airbrakes. I would like a really long runway for landing.
  19. Bruce Tuncks
    I reckon the asi is real important. That and the Altimeter and the CHT's might be all you really need. BUT a mate with a Chipmunk gave me a flight one day.... NO CHT! I said that I flew on the CHT. He said that there never had been one on this plane in 60 years.
  20. Bruce Tuncks
    The only mate who got his son into the airlines as a pilot lived to see his son, plus a couple of other Jetstar pilots, leave the industry. I think they probably did the right thing. The pay and conditions were not very good and they are happier as boutique brewers. At the ASC, we tried hard to assist the tuition fees for some hopefuls. They were good kids that graduated from our program but alas, they could not afford to fly enough and slowly drifted away.
  21. Bruce Tuncks
    Thanks RF guy, you are quite right. I could revisit the math but it's not really the right way to go about the problem. You need prop power curves and engine power vs fuel used etc. But it is still correct that thrust to overcome drag is proportional to V squared ( at the top end ) and power equals thrust times speed and so power is proportional to V cubed. This explains why the first "go-fast " item you do may well give you 3 knots more but if you do ten such things, you don't get 30 knots more speed. Here's a list of "go-fasts" I did on my old Jabiru 1. sharpened the strut trailing edge ( the old struts were very rounded and left a thick wake) 2. sealed up the control-surface gaps and the wing-root gaps 3. Installed an arduino-based cht and egt readout for each cylinder ( Thanks Kevin). Yes this is not really a go-fast but it does allow more engine power to be used without worrying. 4.reshaped the u/c legs for less drag, using tape and foam 5. changed the prop from a 40 inch pitch to a 44 inch pitch ( thanks Ken and Paul) 6. sealed gaps etc in the tail-end of the plane... elevator and rudder mainly. And I can't say for sure how much faster it is... I think about 3 knots but can't really tell.
  22. Bruce Tuncks
    Yep Nev, those radial louvres look good. As you say, the climate there has extreme swings . Mind you, it has been cold here lately but not nearly as cold as a Russian winter. If they had enough blades, they just might fit into the front of the ram-air ducts and this would get them free from the top cowling. Another downside though is that the plane is now more complicated to operate. In the Jabiru, I really like how you don't need to worry about prop pitch, mixture and wheels up lights.
  23. Bruce Tuncks
    I agree Apenname. But you need to factor in the fact that the fuel used will be for less time as the trip will end sooner. My son has a Lancair which has retracts and a 360 Lycoming. It is about twice as fast as my Jabiru and the fuel consumption rate is higher. But his trips are faster and the liters per hundred km figure is similar. Bugger huh. SO... if you double the airspeed, the drag goes up 4 times ( ie squared) so the engine power must increase to compensate and more fuel will be used PER REV. Lets say squared too, although this is assuming a lot about the engine. Now if the revs have also doubled, the fuel used will double again ie cubed..( this is also assuming a lot) But the trip will take half the time, so total fuel used will be halved.
  24. Bruce Tuncks
    I have thought about inlet air control for a Jabiru. Why inlet? well the flaps would not need to seal very well. You could use two flaps, one each side of the upper cowl. The main downside would be the need to disconnect the drive every time the upper cowl was removed, but the upside of this would be that the connection would be easy to access through the upper cowl air inlet holes. Has this been done on a Jabiru or similar plane?
  25. Bruce Tuncks
    I think you meant that shellac and metho are used for french polishing Nev. Not silastic, which is wonderful stuff, I think it was an offshoot of the space race, and it was developed to glue the heat-tiles on for reentry.
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