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Bruce Tuncks

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Posts posted by Bruce Tuncks

  1. If you do as jackc suggests and copy a commercial design, making sure that if it is in a cyclonic area then you copy a similar one, then you should be safe.

    I hope you don't come across an insane buildings inspector like we used to have down here. He is famous for rejecting square footings, even though they were heavier than the round ones on the plan.

    Regarding the dome-type of building, it was good advice to work out the potential uplift from wind and to make sure it doesn't lift on you.

  2. Quite right kasper about high voltage. A long time ago, somebody died when the high voltage arced across about a meter or so to get a control-line model flier.

    He had been careful to make sure that he wouldn't touch the lines, but the ability of extremely high voltage to jump was something that caught him out.

  3. I once was in my own Jabiru and the instructor said he smelt exhaust fumes.  It turned out that he was correct. The fumes were entering at the tail, where some tape under the subfin had fallen off. This enabled some fumes to enter through the control-cable holes and travel up the fuse to exit at the doors.

    This is counter-intuitive but in agreement with Bernoulli.

    These days, at the annual, I take the sub-fin off to check these holes are properly sealed.

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  4. Years ago, some naughty guys used to go into cloud in their gliders. They used a Bohli compass as an a/h, and they caused the Bohli to be banned from competitions.

    They told me that it was quite easy to thermal up under the dome of a big cu, then fly through the cloud keeping things straight with the turn-and -bank gyro plus the asi and the compass. When all gyros were banned, they did the same thing with just the ( non-Bohli ) compass and asi. ( the gyro instruments might have been banned before the Bohli compasses, I don't remember which came first. )

    The lesson I got from all this was that "clouds aint all the same" and there is a HUGE difference between a benign cu at 10,000 ft over flat land and a mean cu-nim which can suck you in and spit you out battered with hail. There is a story about a Canberra jet over Qld which entered a cu-nim at 20,000 ft and was spat out , all battered, at 50,000 ft.

    There is a CASA video ( 180 seconds to live or similar ) which shows a foolish GA pilot flying low and getting caught out by rising terrain and narrowing valley, while trying to stay under the ( lowering) cloud. Again, this is quite different from the 10,000 ft medium cu.

    Mind you, a whole flight under IFR would be beyond me for sure,  especially the landing, so good onyer Mike and Matt. Thanks for sharing the story.

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  5. There was a story about the top Me190 pilot who had a strong ability to withstand negative "g"s . He used to escape by thrusting the stick forward and doing a bunt. Of course he was helped by the fuel injection, instead of a carburettor.

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  6. My in-laws were talked into a 4 wheel van, with a wheel on each corner. It was road-trains that convinced them it could be done.

    Well it towed terribly. It swayed so badly that you had to go really slowly, like 50kph.

    I have seen road trains where the last trailer was kicking dust from each side of the road, alternately, as it sped up the stuart highway.

    I do know it can be done to make them behave, it must be black magic.

  7. OME, whats a YAF ?

    Once I was at the magistrate's court and there were people getting fined for speeding in school zones...  they were mainly on their way      ( they said ) to a funeral and therefore understandably too distraught to care about school zones. This cut no ice with the grumpy old beak.

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  8. The cost of getting a plane certified for aerobatics would be prohibitive I reckon. Personally, I find altitude to be too expensive to chuck away on aerobatics, so I would not pay more for the certification business anyway. In other words, the extra price would put me off.

    But aerobatics done at the beginning and end of the day, with a lightened plane  in still air could not be as hard on the airframe as fully loaded at max speed through turbulence.

    There were rumours about a guy "down south "who was doing loops in his Jabiru....  Ho Hum we said, till we heard that he was starting to do a bit of inverted at the top of the loop.

    So then we predicted disaster, on account of negative loading of a strut-braced wing.

    Well the disaster never happened, and I reckon he just got bored and moved on.

  9. I find it hard to weep over a rich man's toy. But if the plane or car was just inundated, surely it can just be cleaned out?

    I have a farm buggy and the chinese driver's manual says that following inundation, you need to change the oil and other fluids.

    And, I guess, clean out all the mud etc.

    I wonder how much that Mclaren will sell for....  still be out of my reach I reckon.

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  10. Once, I watched in awe as a semi-driver backed into a roller-door in a narrow alley. He didn't have the room to get straight first, so he had to have the whole thing at a curve. I was awed by his skill.... how common is that as a driving feat?

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  11. Not 2 bits of metal in the old Jab prop...  the prop itself is wooden covered with glass,  I'm pretty sure that it was heat that caused the blackening, there was other damage too including splitting around some of the drive-bushes. Now I wish I had taken a pic at the time.

    My new Jabiru 3300 prop is a black-painted scimitar one and this has a metal hub with tight bushes.  I have not yet put a blob or 2 of movement indicator on the hub/driver intersect but I will soon.

  12. thanks nev for that tip about altering nuts for adjusting the torque .

    I agree about air pockets....  they are actually areas of lift and sink, thermals and sinking air. flying though them with a winged plane will cause extra lift and downwards "lift " as they are encountered.  Yes, flying into a sharp-edged bit of sink can seem like you have flown into a vacuum, but that is not the case.

    Thermals have been extensively studied, mainly in Germany, and one of the surprising things, for me anyway, was that the air is more bouyant 

  13. thanks nev for that tip about altering nuts for adjusting the torque .

    I agree about air pockets....  they are actually areas of lift and sink, thermals and sinking air. flying though them with a winged plane will cause extra lift and downwards "lift " as they are encountered.  Yes, flying into a sharp-edged bit of sink can seem like you have flown into a vacuum, but that is not the case.

    Thermals have been extensively studied, mainly in Germany, and one of the surprising things, for me anyway, was that the air is more buoyant in a thermal if it has water vapour in it. ( molecular wt of water vapour is 18, while nitrogen is 28 and oxygen 32 ).

    We see this effect on some summer days when the cu are only over the areas of scrub, where the deep roots are sucking water.

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