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Geoff_H

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Everything posted by Geoff_H

  1. Geoff_H
    For vibration on fixed surfaces I use my phone. There are a number of fast Fourier transform analysis apps that will also give data as to what is exciting the vibration. I clamp my phone to the surface.
  2. Geoff_H
    I had oil filters cut open and magnetic full as well. The major reason for oil testing was detecting engine problems from wear etc that has started but is not able to be detected by any other means. I flew the craft every week where possible. As a professional engineer I have always been a believer in preventative maintenance. Aircraft engines are the same as automobile engines. Automobile engines are used for far longer than aircraft engines and have no mandatory overhaul times. Most wear in my Mooney came from the engine idling waiting for the oil to get to temperature so that the constant speed propeller or the pistons getting hot before the bore and ceasing would not happen on take off. Is appreciate that engine failure in visual conditions usually only means an outfield landing, with possible damage. Night flying is far more dangerous, I have not done it for years. now that I am older and suffering from the normal degredation of night vision.
  3. Geoff_H
    I often flew in IFR in the dark, night VMC in the outback. Engine failure would probably meant my death. Maybe that is why I put so much emphasis on engine health. I don't think that there is any economic value, unless when buying an aircraft it could alert to an engine with issues.
  4. Geoff_H
    Blackstone would disagree, failure can be detected long before anything is obvious to the naked eye. The smallest of quantities show up with a mass spectrometer. They can even say if an engine is not wearing in properly. Many owners of top end GA aircraft do testing from engine new or overhaul. I find it interesting that it appears that LSA owners don't see the value in oil testing as a preventative measure.
  5. Geoff_H
    I have used these people. Aircraft | Blackstone Laboratories
  6. Geoff_H
    It can be done in Australia, just need mass spectrometer. But with an aviation specialist they will give heaps of additional information, they need to know what engine the oil is from. It is not that expensive when considering the cost of an outfield landing. Magnetic particles in oil tells you about a condition of the engine a long way into a failure. O paid around $400 for around 10 samples, plus USA postage.
  7. Geoff_H
    I am just wondering how many of us subscribe to NDT of our engines. After all the engine is rather critical to sustained flight. How many get their oil condition tested to see upcoming engine problems? How many know many different conditions, including piston wear can be determined well in advance of them happening by sending off a sample of oil to one of the many condition monitoring places?
  8. Geoff_H
    The goggomobile used the generator starter motor, the one device for starting the engine. The engine was 2stroke. 4forward gears, 4reverse gears. For reverse start the engine in reverse. Gas turbines for power generation use the generator as a motor, when up to a speed where combustion can continue, turn off the motor, run the turbine up to speed and connect the generator. Modern car engines have big generators to supply the electrical load, I wonder if these could be used to start an engine, maybe just push the engine to a position where spark ignition could start the engine.
  9. Geoff_H
    Yes. Broke my heart to sell her but the wife started to refuse to travel in a light aircraft and even reluctant to travel in a commercial aircraft. When I retired I no longer needed to use NWF.
  10. Geoff_H
    Annoying much younger days in the 70s I used to play with Holden V8 a 4.2 litre V8. If you put to bigger Holly on it the performance was less than if you put a smaller Holly on it. A lot to do with turbulence and mixing of the fuel and air.
  11. Geoff_H
    Sometimes a wide open throttle will allow Laminar flow in the inlet manifold, sometimes the air/ fuel mixture will wall attach, either way you will have a ahot lean stream with a cool rich mixture. The heat from lean mixture is two fold owing to the flame front bring so much slower that your crank is not in the best position for absorption of the hot gas energy etc. Maybe put a small obstruction just after the carburettor to get good mixture. Also use a carbon monoxide Meyer in the exhaust and time engine to a barely perceptible reading. Impossible to tell without instrumentation.
  12. Geoff_H
    Well maybe ?. But I don't wish to rip the wings off doing some aerobics. The trim systems maybe two rubber springs opposing each other. Their centre position the trim position. Steel springs would not add to the control force for g's pulled. The hysteresis in rubber may be able to do just that, it's a design thought at the moment.
  13. Geoff_H
    What I am after is what is that artificial quantity, I know it for stick/ yoke but not sidestick. Is there a difference. My design will have artificial feel done by hysteresis in rubber springs. Any pilot that has used sidesticks for aerobics?
  14. Geoff_H
    Does any airbus driver have any comments on the forces needed verses the g the aircraft pulls?
  15. Geoff_H
    Mooney have a power earth with one connection to the airframe and at the other end of the earth strip a connection to the instrument earth bar. Instrument earth isolated from the frame. It stops earth loops and allows you to hear over the radio squark. All shield conductors MUST be only connected at one end. Same reason as above. I did a nice income getting communication systems to work that had been installed by others, usual problem was shield earthed both ends.
  16. Geoff_H
    The attached PDF shows the increased current carrying capacity for Teflon wire vs other insulation. Tefzel is similar to Teflon but is significantly lighter. If you were designing an electric aircraft Tefzel would contribute significantly to weight reduction. WIREMAX-conductor-CURRENT--2- (1).pdf
  17. Geoff_H
    From memory the FAA require at least 10pound of stick force per g of aircraft load. With a stick it would appear easier to pull 6g, 60lb with your arm free to move. My question is is that still the case with a sidestick when you appear to be just rotating your wrist. Or Have I got the sidestick wrong?
  18. Geoff_H
    The current carrying capacity of a conductor is limited by the maximum temperature that the insulation can take. Smaller conductors generate more heat so a higher temperature insulation can carry more current for the conductor
  19. Geoff_H
    Yes but the FAA dictate that you must have to use a given force for a g pulled on the aircraft. So you don't accidentally pull 12g etc. Is that requirement still the same for a sidestick where you have significantly less movement.
  20. Geoff_H
    What is the feedback force of a sidestick. I know the force per g for stick and yoke, but not sidestick. I am designing my aircraft to be able to adjust this force through a huge range. It would be nice to know around now ( designing the trim systems)
  21. Geoff_H
    Tefzel and Teflon give off more harmful smoke than PVC, if that is possible. Probabily dead either way. Believe me the only advantage of Tefzel and Teflon is weight. Significant weight reduction.
  22. Geoff_H
    Tefzel uses tin plated copper as a conductor. Tefzel is used because you can get a much lighter wiring system than PVC insulated wire. You can use a conductor that is smaller in size than with PVC insulated wire. Any copper reduction can make a sizeable weight reduction. Tefzel insulation is lighter than Teflon (although it has many similarities), so it is the lightest weight for any conductor. It is difficult to work, being slippery skinning and mechanical connection to the insulation is difficult and must be done with the highest quality crimpers. I would just use PVC insulated wire in a small aircraft.
  23. Geoff_H
    Oil pressure has little to do with the load carrying capacity of a journal bearing. Oil pressure just ensures that there is oil between the journal and the bearing. The load carrying capacity is a function of the oil wedge formed between the bearing and the journal.
  24. Geoff_H
    Lycoming did change their design they put in roller followers. I chose not to go this way because if you have a prop strike you have a sizeable bill because they have to be either inspected or replaced I can't remember, but it wouldn't involve more cost over the straight engine disassembly on a prop strike. Getting old so sure of my memory anymore
  25. Geoff_H
    Sorry for the few errors in the previous post I'm using voice to text because I'm a bit pressed for time. Please use your imagination
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