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Geoff_H

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Everything posted by Geoff_H

  1. Geoff_H
    Some years ago I designed and partially finished the prototype of a very similar project. The two halves of the fuselage were a top and a bottom. The main issue with a monocoque skin. A section between bulkheads has to have buckling resistance. This is where I had difficulty with design,a single skin thickness either had a large weight to resist buckling of many bulkheads close together, I chose a composite skin, bad choice in retrospect. I had to mould a core to shape then "glue" it to the outer skin then epoxy a layer on the inside. Without the ability to experiment with strengths of composite structures I made it far too heavy. I was looking at doing a master's in aeronautical doing experimental techniques until I got an away from home contract and abandend the project. Maybe stringers that were cast and attached to the skinsin the moulds would have been better, hindsight is so 20-20 vision. I made two tails, one using this method and one using cut foam with a cast skin attached ( no sanding required) the greatest surprise was that there was no measurable difference in the final weight Good luck with your project. Geoff
  2. Geoff_H
    Yes Nev, getting old is a privilege denied many.
  3. Geoff_H
    Thanks Red. I getting too old. 😒
  4. Geoff_H
    Anybody know anything?
  5. Geoff_H
    My heads up display in my car is invisible with polarised sunglasses. I have two sets of sun glasses, one for driving, one for out of vehicle activities.
  6. Geoff_H
    Is thermal efficiency mechanical energy out divided by chemical energy in (ie fuel energy)?
  7. Geoff_H
    I didn't think that I had monocular vision but the optometrist told me I do. I hate glasses and have better vision than when I did use glasses then contacts. The monocular vision is more of a problem during the class 2 medical.
  8. Geoff_H
    I have roughly sketched the mathematical reason for engine speeding up as aircraft moves forward. Sorry it is so rough but somewhat busy at present. In summary, as the aircraft moves forward angle of incidence of prop blade to air gets smaller, thus the drag on the prop gets smaller so the engine speed will increase
  9. Geoff_H
    So if you stay in the cabin the electrons will flow through the skin of the aircraft. Just don't touch two different parts of the skin as you may get a potential difference through your body and electrocute yourself.
  10. Geoff_H
    With high voltage you never get electrocuted. Electrons repel each other so the current flows over the outside of the skin not through the body as required for electrocution. It does however create enormous heat and creates extre burns. HV burns you.
  11. Geoff_H
    The cabin is intact. Mooney's have a very high survivability. The cabin area is a steel space frame. The tail is monocoque structure.
  12. Geoff_H
    I think that the problem that I have with CASA is that it is perceived that i cannot judge distances with monocular vision. However this is not absolutely true. When trying to judge distances at very short range, around 6 inches, yes I have difficulty, th thread a needle by holding the needle axially, then it's just a matter of up down sideways movement. But catching a ball is no problem. Although my left eye is not in focus it is still used by the brain. The brain detects the the centre of the fuzzy ball and uses this and the infocus eye for distance perception. I am around 90% of before eye operation effectiveness. How I see 3D movies is still a wonder. My optometrist, unhappy that I am not buying glasses anymore, said that I could not catch a ball with this vision. It seems that this is a widely held misconception. I expect that this is why CASA believe that I need eye correction when flying. From what I read of USA situation is that if an eye specialist says that it is not restricting you you can get an exemption to needing eye correction. How do I get thos exemption in Aus. Do I go to politicians, eye specialists? Any and all ideas welcome! Geoff
  13. Geoff_H
    I think that the correct term is monocular as theoretically only one eye is being used at a time. However the reality is that both are usually being used. They are lenses the same as every person gets for cataract replacement.
  14. Geoff_H
    Had mine for 8 years now. My left eye has a 2 dioptor in it. I can read to around 6 inches up close
  15. Geoff_H
    Yes that is right. The brain is amazing. I am in awe of its capability.
  16. Geoff_H
    At present CASA does not appear to allow a Class 2 medical for monocular vision without correction. I believe that it is possible to get a Class 2 without correction if a suitable medical professional approved it. I have monocular vision, by choice. Upon replacement of lenses for cataract correction, I have a vision range from 150mm to infinity. I do not have vision correction for all aspects of life. Including 3D movies, the most surprising thing for me. Distance measurement is 80% of normal vision, I can still thread a needle without correction. Although not in focus in my left eye it is still used by my brain for distance use. My question is does anyone know of a way that I can get a medical exemption, similar to the USA exemption? I am starting to do aerobatics so I want the Class 2 med.
  17. Geoff_H
    With some research on the internet, and buried deep inside a website I found that the Oil is a long life 4. Penrith agree. So I have used that.
  18. Geoff_H
    A little off topic but in line with doing our own maintenance. Got a message from the car saying that I needed to add 1 litre of oil to the engine. So I looked up the owners book. It said that oil specification was on page 366. Only problem is that page 366 has never been bound into the book. The next page says to buy oil from BMW. Is this allowed to happen under state Law?
  19. Geoff_H
    Bruce, may I be so crude as to ask your age? I have just started to allow one trusted garage to do work on my car's. Still do simple stuff, stuff that takes less than a few hours. I absoluely agree with the having to get up to get the tools I forgot 😁
  20. Geoff_H
    Are parts available for Camit2200 engines? How reliable are they?
  21. Geoff_H
    Sorry but the speed of sound is not purely a function of the temperature. It is a function of the density! In a gas temperature is a significant contribution to the density.
  22. Geoff_H
    My car does not have a wheelbrace. Nor a spare wheel. Destroyed two wheels recently. Drove about 10km on flats at 80km. Not the normal precise steering it normally has.
  23. Geoff_H
    Only go to a garage that has a torque limiter attached to a rattle gun. It is what I do with my alloy wheels, observe the setting and attachment of the device. And when they say that they won't let the car back on the road without them as tight as possible, inform them of their knowledge inadequacies and publish the company on social media.
  24. Geoff_H
    The stud is a spring. Steel is elastic and by extending it just a little very large forces can be generated to hold two things together. How much force is a function of pressure in a cylinder or sideways forces on wheels. The true way to determine the force is to measure the bolt extension. Difficult on small bolts, easily done on large bolts. The extension on small bolts is infered by the torque applied to the nut. The wedge force determines the bolt force by mechanical infered calculations taking into account friction in the nut. Bolts can be over stressed particularly when it is the first 1.5 threads that take the overwhelming part of the strain. It the wheel nuts are overtightened the threads are put under stresses that will allow the thread areas of both the nut and bolt to permanently deform and eventually break the bolt or strip the thread.
  25. Geoff_H
    In the 1970's I was commissioned to do a study on bolt failures. Amongst the things that I discovered was that 90% of the bolt load is taken by the first 1.5 threads. So over tightening, using the full impact force of a rattle gun just damaged the threads. The tyre service I use these days has a torque limiter on their rattle guns. I was able to use the cars wheel wrench to change the flat tyre. If your tyre fitter over tightens the bolts you are at risk of stud failure.
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