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Geoff_H

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Everything posted by Geoff_H

  1. Geoff_H
    As an aside the advertisement that I placed for making moulds should have read "person needed to make aircraft moulds. At your place" and so on. Advertiser printed "person needed to make aircraft. Moulds at your place" and so on. What a difference a full stop placement meant. No wonder CASA called and threatened.
  2. Geoff_H
    Yes KRviator it is 51%. I had better pay attention to the details. Some one may have built only 50% and had their aircraft rejected. Personally if one doesn't do as much as possible they would probably be better buying a built aircraft.
  3. Geoff_H
    When you build an aircraft, even fast build kits, you will put at least 500+ hours into it. At $30/hr that would add $15k, and make something like a onex cost $90k. Might as well buy a factory made craft
  4. Geoff_H
    I have no idea how CASA handle the sale of a partially built aircraft, the did have a group monitoring the amateur building, maybe not any more. In the 70's there were a lot a accidents, world wide, from home built that were not registered, that's when they introduced experimental class. Our was a carbon copy of theirs some 20 years later
  5. Geoff_H
    CASA told me it had to be me. They were quite annoyed that I was advertising for someone to do some work.
  6. Geoff_H
    You should keep a log of your building. You could invent entries, but also expect inspections along the way. Answering intelligent questions to the inspector could be difficult and give you away
  7. Geoff_H
    It has to be you. The specifications for experimental are for aircraft development or the learning of the builder. In the 70's it was stated that with the rules of the day the Wright brothers would never have been allowed to fly their aircraft. I was building a moulded aircraft some years ago. I advertised for someone to build the moulds. The publisher of the advertisement left a full stop out of the advertisement and it read like I wanted to get someone to build the aircraft for me. CASA called to tell me that it had to be 50% by me. As an aside no one answered the advertisement and I gave up. Maybe you could make a group of people, make the aircraft and do little, but make the paperwork look like you contributed an equal share, might work. But look at the fun that you would be missing out on.
  8. Geoff_H
    To be in the vh experimental class you must build 50% yourself
  9. Geoff_H
    Yes.i did it on a vh licence. Unsure what other restrictions are.
  10. Geoff_H
    The RAAF give you an authorization number. When requesting clearance to enter military CTA you will have to quote this clearance if your aircraft is not based at the aerodrome. If just passing through restricted zone civilian traffic controller will organise it
  11. Geoff_H
    Hi Callahan, I am 69, about to be 70. Have you checked the vibration damper in the gearbox input? Geoff
  12. Geoff_H
    Hi Nev, The aircraft is single seat. 12 ft long, 16ft wingspan. Cramped as can be, looks a little like a coffin at present (LOL)
  13. Geoff_H
    Thanks. I didn't realize that gliders use sidesticks as the pilot is recumbent. I can calculate all the forces and moments etc, I can't open any of the NASA cr1975 documents, do they contain any ergonomic data? Any glider pilots that can tell me what makes a good system and bad system, do any of them wish that they had a joystick?
  14. Geoff_H
    I am at that point in the design and construction of my little aircraft that I must commit to either a side stick or a joy stick. I have never flown an aircraft with a sidestick. Has anyone here done that? I read a report on the Sirrus 22 that said that the sidestick was the cause of accidents as it used springs for pilot feedback nor aerodynamic force. The sidestick has less movement and hence must have a different feel to it. Also the problem/advantage with a sidestick is that the pilot can be recumbent and hence present a smaller frontal area, but lying down more pushes the CofG back, not nice, I would have to compensate by moving engines forward, possible but adds to the weight.With a joystick recumbent is not possible as you have to reach the joystick between your legs (shh). Any thoughts or suggestions Geoff
  15. Geoff_H
    Loved them. Especially the rocket near the bum design, must try that
  16. Geoff_H
    Imagine the research needed to develop a good, and safe, control system. Love the fact that someone is trying, what aviation is best at doing.
  17. Geoff_H
    In WWII pilots we're trained at Temora with one hour in the classroom and then one hour of physical fitness followed by daily flying. These were you guys! In my late 20's I would do one hour of flying per day after 8 hours of work, that maxed me out. Now nearly 70 I would be lucky to learn at a max of 1 hour per day. I guess it's a matter of how much you learn in a day, any extra flying is just wasted money
  18. Geoff_H
    Have you checked out the condition of the vibration absorber's in the gearbox?
  19. Geoff_H
    In a 2 stroke miss. Can be due to gummed up rings. Usually at higher loads, not sure that gummed up rings is the problem, usually occurs after a long period of not being used
  20. Geoff_H
    Hi Bill, a few questions. What did you do,if anything, to the aircraft just before the vibration? When you place the prop on did it go into exactly the same place? The FFT programs available for Android have a 250hz max, this is close to middle C in music. Is your frequency higher or lower than middle C? If it is higher it may be in the gearbox, oil level can be critical to tooth lubrication, what is the oil level? Are you running the right oil for the temperature zone of the aircraft? Cheers Geoff
  21. Geoff_H
    If I remember vibration studies in reciprocating Engines (over 40 years ago) 2nd order harmonics (twice Engine speed) are high when Engine disturbances are present. Things like bad spark etc, can cause these. At 3600rpm these will have the same frequency as a utility transformer. Does your vibration sound around that frequency?
  22. Geoff_H
    If you wish to get highly scientific about this investigation there is one other option that you can do. I used it some years ago to analyze a vibration in a Turbine. Download an FFT from play store (or maybe they are available on Apple). Fix the phone ridgidly, really ridgidly to the aircraft frame. Induce the vibration and record the result. It will be a frequency vs amplitude for a multitude of frequencies. One can be expected to be much higher than the others. Identity the base speed of the Power Plant. Now you need to get a whole lot of data about the Engine, drive train and prop. One item needed is the number of teeth on the two gears in the gearbox. The meshing of the gears will create vibrations according to meshing frequencies and hunting frequency etc. Doing some maths you maybe will find a characteristic frequency that matches the large amplitude on the FFT (Fast Fourier Transform). This is involved but if nothing else works I can recommend it.
  23. Geoff_H
    Have you checked out the Engine mounts? After over 30 years they may have gotten hard or even disintegrating, anything that changes their spring rate will change the natural frequency and consequential transmissibility of vibration to the aircraft frame. The natural frequency is usually about a tenth of the running frequency or less, as they harden the natural frequency increases and do the transmissibility of vibration, it starts to be noticed at lower frequencies. If they are disintegrating it may be just impact of Engine with something hard.
  24. Geoff_H
    I wonder how many aircraft kit manufacturers have gone out of business through less than astute business practices leaving many kit makers on their own and regretting buying the now orphan.
  25. Geoff_H
    The KKS was developed for the power industry, but is most adaptable to any project, both large and small. The subtle advantages of the system is the ability to change a part and number and use it as an inventory control. It uses a plant based numbering system rather than a part based system, hence for a manufacturer the actual part ID can be hidden, a $2 part can easily be sold for a much larger value as its actual industry part number is hidden. Also rather than an "AN123456" the part would look like x3-u02, this seems impossible, however one quickly learns that it is a washer 3/16OD made of stainless steel etc. At first the system seems impossible but one quickly learns the numbering system and a bag full of 3/16 washers means little. But I found that outside of Europe it has resistance to implementation, the Americans would rather a complex number only based system. I found that the European Engineering to be far more organised than the rest of the world, they pay their engineers very well and expect them to do their job quickly and accurately. It seems like KKS is not for this job, but if you ever need any information on it let me know.
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