Geoff_H

Loved them. Especially the rocket near the bum design, must try that

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.

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

Have you checked out the condition of the vibration absorber's in the gearbox?

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

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

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?

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.

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.

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.

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.

PS I have used it on several occasions. I swear by it.

The very best numbering system for very large scale projects for both design and construction is the KKS (German initials for K? K? System). It is freely available to use and allows both designer and manufacturer to instantly know most of the number of the part. It uses alpha numerical letters to avoid confusion. If you areinterested I am prepared to show it toyou but not by dozens of emails, it would have to be by meeting, I will go to yourself, I have to go your way soon.

I have done it on several occasions, albeit for short periods of time. Unless the airstrip is where you work you will need a second vehicle at the airstrip. The timeto care for the car (fuel etc) and tying down the aircraft only seem to make it quicker if the vehicle journey is over around two hours. It is somewhat stressful to always have your eye on the weather and winds. But it is more fun than driving

Half your luck. It looks great. Was that way a few times when I had the Mooney. Love the NT, particularly at this time of year.

They probably use capacitors and inductors to isolate the noise, then to prevent radiation directly place a conductive shield rather to the aircraft earth. Also shielding the cable, again earthed to the aircraft earth, to prevent the cable being an aerial to the electronic device connected that self contains radiation.

You can buy integrated circuits that will control 5VDC. They have over current and over voltage protection. The noise may also come from the cable acting as an antenna, shield the cable with foil and earth one end only, this is very important.

Tried wrapping your device in foil? Best to earth the foil. Without actually seeing the situation I am guessing that it is noise from the switch mode power supply, probably very cheap and lots of side frequencies.

Anyone know where I can buy 2024 T3 or T4 Aluminium tube in Sydney. A while ago I found a place down Campbelltown way. Can not find them on the internet.

The lawyers have no conscience. They go after anyone with any assets. A senior lawyer will charge $700 per hour. If they get a judgement for their client their percentage varies according to the level of the court that gives the final judgement. Can be as high as 60% of the judgement. Unreal. Lawyers and CASA make the LAME's life hell. Many will avoid most things that they have to sign off on.

Agreed. But even my Vanguard engine designed in the 50's had forced camshaft lubrication. In the rebuild of the Lycoming Engine I paid $1800 for an STC to drill holes for camshaft to change it to forced lubrication. My feeling is that both Lycoming and Continental are hiding behind the too hard to get approved curtain. After all Porsche got approval for a modern single control with computer systems in the 80's.

I often think that mass produced Engines such as vehicle Engines are more reliable. My Lycoming did it's camshaft in a few years ago, luckily found from metal in the oil, never had a car Engine problem in the last 40 years.

TCM 850 another turboprop aircraft designed by Mooney but made by their previous owner.

I seem to remember some years ago reading why those early business jets were so cheap to buy. The article said that it was because they were so fuel inefficient that they cost a fortune to fly. You might look into this. When I win the $30M lotto I might buy a more recent one.

Yes I had two epirbs, one that used the aircrafts GPS to instantly transmit coordinates the other a portable. Despite having two comms I always carried a hand held com. And two portable gps'.never have too much safety.