Bruce Tuncks
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Everything posted by Bruce Tuncks
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I'm retired too... never worked so hard in my life. Actually I "retired " at 50, and the first thing I did was build a kit-house for my son. It was much harder work than I had got used to. I remember using a "U " tube for leveling the house while the real builders all around used laser levelers. ( the real builders all used the f word all the time and one day one of them made a mistake which nearly got him thrown off the effing roof by all the subsequent lots) . It was all great fun.
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Macron banning private jets
Bruce Tuncks replied to lee-wave's topic in UK/Europe General Discussion
If you think our farm is not important and want to do the whole planet, here's a start. The surface area=5 times 10^14 m^2 at 15 km height ( guess!) the volume is 7.5 times 10^18 m^3 Then the weight is the same in kg. 1 millionth of the atmosphere is 7.5 times 10^12 kg so 1ppm of CO2 reduction means removing 7.5 times 10^9 tonnes, that is 7.5 billion tonnes! Seems a lot, so I hope this is wrong. -
Macron banning private jets
Bruce Tuncks replied to lee-wave's topic in UK/Europe General Discussion
I fly and believe in global warming. I would gladly remove the CO2 that I put in the air by my flying, but this would be futile unless everybody else did too. Each liter of avgas used would need approximately a kg of charcoal to be buried.... no real problem, Here's another way of looking at the atmosphere... 1 cubic km of air weighs about 10^9kg and 1ppm is therefore 10^3kg or 1 tonne. So 1ppm = 1 tonne per cubic km. If the atmosphere goes up to 15km ( ie could be replaced by a 15 km deep layer of 1kg/m^3 ) then there are 90 cubic km of air over this farm. ( yep, the farm is 1500 acres or 6 km^2 ) To lower the CO2 from 420ppm to 280ppm would mean removing 140 times 90 tonnes of CO2. Wow , 12,600 tonnes of CO2 ! That is possible but it will take years of work Gosh I hope somebody does a check and finds I have overstated the figures. I find it easy to believe that 12,600 tonnes of CO2 could alter the thermal properties of this bit of atmosphere by enough for 2 degrees of warming. -
Some of the posts here, and in the original article, appear to suggest that a structure is stressed by the G forces alone ... this is WRONG. The structure is stressed by the product of the G force and the weight. I have always believed that slowing down in turbulence makes you safe, and flying light makes you safe too. I'll try again to understand the article. ( I failed first time due to being slow and not too bright ) The worst turbulence I have flown in was a frontal zone. It felt like you were a rat in a shoe-box that was being shaken as hard as possible. It was impossible to keep your feet on the rudder pedals. One passenger was scared stiff.... literally !. He was lifted out ( stiff ) by about 5 guys. Everybody slowed right down to about 60 knots and nothing was damaged, except for the guy outlanding when the lead-acid battery exited from behind him through the canopy. But that was caused by an improper battery installation.
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Good stuff guys. I agree that it is only for take-off that the extra cooling is required, so the weight of the water should not be a problem. It was real interesting how NACA once seriously considered using the water in ordinary exhaust gasses ... While a hydrocarbon burning in oxygen must produce water, I had no idea that the weight of water so produced could exceed the weight of fuel burned. Not for us lot tho..... too heavy and complex for the savings.
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How is it injected Ian ? Is it injected into the inlet plenum ? I find the idea attractive.
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kg, I reckon, from your info, that Jabiru have done a bit of work and put on a big markup. The thing arrived assembled and the spinner was drilled and cut-out. There were some crack-indicator blobs of paint around the pitch-adjusting bolts too, which leads me to think that the pitch was set at the Jabiru factory. I will find out next week I hope.
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Thanks guys... I didn't know it was made by bolly. Yep I downloaded and printed off the manuals, but for example it didn't say whether the one I had bought had already been balanced. As regards balancing... the 4 bolts which attach the prop to the engine could instead attach to a plate. Then you could make a small hole in the center of the plate and use this for balancing. Maybe a string or fine wire to suspend the prop from this point.
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They told me that these were selling like hot cakes so of course I bought one. $2000, and to make things worse you need a new spinner at $300. Anyway, the prop looks good but it came with no instructions. Does anybody know the torque to tighten the main ( 1/2inch spanner size ) bolts to? Any other comments about these props would be welcome.
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I thought about the problem and decided to use the alternator for the tacho. It worked just fine on my system ( I reduced the voltage to trigger the pulse.) Well the guy who looked after the club plane wanted one too.... alas, the thing stopped working at 3000 rpm on the club plane. All you need is a pulsed something in synch with the rpm.
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Referring to a tension-member with carbon fiber "reinforcement", if the carbon fiber is ten times as stiff as the wood, then it will carry ten times the load that the wood does. ( assuming equal cross-sections of each material) The ten times as stiff does indeed refer to carbon fiber and bamboo composite.
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Space, I reckon that the bamboo as described ( stronger that steel in tension and much lighter) would be ideal for a prop, alas its too early to try one. The material is just in a report from Zurich university, so there are years to wait.
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Not necessarily Marty. The materials, having different stiffnesses, carry loads differently. An extreme argument ( Yenn or old K, ) was that of carbon and wooden structures. Basically, the carbon carries all the load till it fails, only then does the wood carry load. This is indeed fairly accurate.
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Powerandpassion, I was very interested in the story about testing qld maple for mosquito props in 1940. This shows far more thought than I thought went into the mosquito project. What do you think went wrong? I always reckoned it was that Australia didn't have the skills to make the joints close enough for the non-epoxy glues they had then, but there is obviously more to the story than that. Gosh, a squadron of mosquito planes in 1941 would have been great, alas it was not to be.
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It was onetrack who made the posting, about bamboo, and it was on the other site ( off topic gets you there ).
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There is a very interesting post ( elsewhere on this site) about a bamboo composite material, which may turn out to be great for props. In the meantime, I am embarrassed to admit to buying a new Jabiru scimitar prop... $2,500 dollars ! I reckon I still would like to make my own. Maybe copy the bought one? this would possibly be illegal, but it would be fun.
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Is casein susceptible to going rotten? I think I have heard of casein "remembering" it was made from milk and reverting with heat and humidity.... But it may be animal glue I am thinking of.. that stuff stank like hell even when it was done properly.
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Fliterite, you are wrong and jackc is right. The Arabs have horrific road accident figures, partly because their religion is fatalistic. They think the time of your death is set by Allah and there is nothing they can do about it. So they don't wear seat belts etc.
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Unlike the UK, Australia did not have thousands of woodworking craftsmen... that was also part of the story.
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Thanks Nev. I had read that a pommy inspector came out and condemned all the australian mossies. Except for the first one, which broke up and killed its test crew. I thought then that the glue joints were the problem... I didn't know for sure it was casein, so thanks for that.
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Thanks Ian... You have got me wondering , all my life I reckoned that resourcinol was inferior to epoxy because of its lack of gap-filling properties, but as you say, in glued laminations, this should not be a problem. I'd like your comments about the Australian ww2 Mosquito bombers. My understanding was that they were not built well enough to cope with non-gap-filling glues. Epoxy was only invented after ww2 I also think.
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The pic is the front wing of a dragonfly. Note the turbulators and the elevon trim-surface. The plane is very comfortable and high-performance, with about 15 more knots on a similar ( jabiru 2200 engine ) to an SK Jabiru.
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back to the viking dragonfly,I have flown in one and agree with the 49 knot stall. The dragonfly is a tandem, and set up so that the rear wing will not slall. This limits how slow you can fly it. Remember the Rutan Solitaire powered glider? It was a canard and couldn't stall the main wing. But it couldn't thermal either, with its inability to fly below 60 knots. So what is the stall speed of an " unstallable"plane? If you take it when the front wing stalls, then the 49 knots for the dragonfly is about right.
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When the windmill stops.
Bruce Tuncks replied to old man emu's topic in Student Pilot & Further Learning
There was a slight wind from the NW if I remember correctly. The glide was into Stonefield from about south-east of Eudunda, starting about 6000 ft. I got there ok and wanted to set up to land on the long E/W strip, from the east... about 28. But on turning onto base leg, I was too low! The whole thing can be explained by stupidity. There was so little wind, that I could have landed downwind safely. Also, I could have done a close-in circuit and always had the option to get to the strip. There was nobody else around.
