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Bruce Tuncks

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About Bruce Tuncks

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

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  • Aircraft
    jabiru sk
  • Location
    Gawler, South Australia
  • Country
    Australia

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  1. A very interesting discussion rf and facthunter. Thanks. Here's my guesses... My old 700 hour engine runs fine but the stiffening up is so marked when you hand-turn it hot that I think this cannot be happening when running or the engine would seize. Could it be that some internal heat-soaking is taking place after the engine stops? When taxying to the hangar after a flight, the cylinder head temps are all about 130C. I understand that an aluminium piston in a steel cylinder would tighten up on heating, actually your calculations rf show this to be less than I thought. But that heating pic
  2. Quite often, we get stuff about how the airship will have a resurgence but it doesn't seem to happen.
  3. I have read that the hydrogen gas has been given an unfair amount of the blame and that it was the nitrate-doped linen which was the worst culprit. Nitro-cellulose is an explosive, and nitrate-doped linen is pretty close to this.
  4. Quite right Nev. As a kid, I had 240 volt shocks but never a bad one. For example, if you are touching the active wire (240 times root2 max volts ) but your hand is dry and you have sneakers on ( rubber soles) then you have a very high resistance path for the volts and while you will feel the jolt, it will not hurt you. On the other hand, if you were touching a ground with the other hand and your hands were wet, at least a thousand times more current will flow through you. Our 240 volt system is in my opinion better than the american 110 volts as our losses are less. But yes it can
  5. These days, parts are laser-cut directly from computer files. Apparently Caterpillar make their heavy machines to order this way.
  6. I read that the ships of yesterday used plywood templates made in the loft to cut the heavy steel bits. Due to dimension changes from humidity etc, they often had 50mm gaps to bodge up in the steep bits. This was especially bad if the steel was really thick like in a battleship. So onetrack's advice is good.
  7. What do you reckon is the minimum strip length for a Jab, blueadventures? At the farm here, I made a 550 meter long strip which I landed on a few times, but I have been spoiled by the much longer strips at Gawler. My experiments showed that 300 m was long enough , but that allows nothing much for errors, and so I was scared of the 550m. I know of a strip which is 250 m, and I guess that this would do provided there was nothing higher than a farm fence at each end, and it was into the wind.
  8. Correction... it is not that cheap at the moment to make methanol from hydrogen and CO2 but there are research places trying catalysts etc and hopefully this will change.
  9. I reckon the future might have synthetic liquid fuels. For example, methanol ( CH3OH ) is what model planes used to use before being ousted by Li-Po batteries. If you have hydrogen, I think it relatively easy to make methane (CH4) and then methanol. I dunno if I agree with you kgwilson. Electric battery planes are cost-effective right now for some applications like training and gliders. A tenfold improvement would see battery power good for most of us who fly for an hour or two most of the time. And they sure displaced methanol model plane engines just on convenience grounds, with no ince
  10. I thought Einstein was impressed by the fact that inertia and gravity cannot be separated out. Thus was born the idea of space-time and that gravity was the effect of warping space-time. If this were not so, you could imagine an instrument which was a perfect artificial horizon. BUT what about the Higgs boson, I wonder... " the particle which bestows mass". In my poor understanding, this runs counter to the space time stuff.
  11. My opinion is that OME is wrong about the kilograms but right about the spirit level angle of attack thing. If you are travelling at constant speed at a constant height, then of course the spirit level will tell you the angle of the chord line if it is properly mounted. This angle will increase as you gently slow down. Until you stall. Whether or not this is a useful instrument in the real world is another matter. On my Jabiru, the stall warning horn thingy is an amazingly long way towards the underside of the leading edge, and the whole plane is correspondingly very nose up at the stall.
  12. best wishes James . I reckon you will have a lot of fun. At least to start, try for calm days for flying. Yes I know NZ is a windy place.
  13. Back in the olden days when I used to teach this stuff for a living, the kg was a block of platinum held in a vault in Paris. The unit of force was the newton, which would accelerate a kg mass by 1 metre per second per second. The unit " kilogram weight" was frowned upon because it involved knowing just what the gravitational acceleration is. If you take this as 9.81 m/sec2. then AT THAT PLACE a kg-weight is 9.81 Newtons. There is an instrument called a gravimeter which measures this 9.81 variation very accurately and for example will help you find buried minerals. A geophysics mate
  14. 60 degrees is some bank angle for sure. Once I watched 2 awestruck at 2 big open-class gliders climbing in a narrow thermal core at about 60 degrees of bank. The wings were noticeably curved from the g loading. They were climbing well. 45 degrees seems very steep when you actually do it too. The diagonal instrument screws are parallel with the horizon. The g forces are noticeable too. I reckon few power pilots have ever done much of this. In a lightly-loaded 15m glider you need to do 45 degrees at 45 knots accurately and this is an impossible goal, but like a perfect golf shot, you need
  15. There is a lot of nonsense in the wine industry, and the one about quality is proportional to price is the biggest bit of nonsense ever written. Price is determined by how much you can get for it. There is a niche for real expensive stuff, bought by people who are trying to impress others. Here's the truth... wine made from good grapes with no stuff-ups by the winemaker will be good. In Australia, it is hard to buy local wine in bottles which is poor quality. The bottling etc is just too expensive to waste on bad wine, and also the winemaker will have his reputation to think of.
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