nlappos

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Posts posted by nlappos


  1. Note the Conclusion of the Avid AD letter I posted, "Avid recommends that a clear filter be installed at the inlet to the header tank."

    But to each his own!

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  2. I had a similar occurrence when I watched my upstream fuel filter empty itself as I flew, indicating I was burning gas faster than the tank was delivering it. I landed at the nearest airport and saw that the bronze screen in the fuel tank pickup had clogged with small stuff. I removed that screen and things got better fast. The original builder, Jim Peet, made sure that a clear filter was put near the input to the header tank, in easy sight of the pilot, so that a glance every now and then can assure that a steady stream of fuel is refilling the header tank. I show a shot of 52X with the yellow filter just visible inside the left door. Maybe everybody has this filter.

    P1010188.jpg


  3. The horizontal tail usually produces a down force to balance the airplane, especially if the aircraft CG is in the middle or forward. That is why most tail airfoils are symmetrical or upside down, the tail is flying upside down most of the time. When the tail needs to most lift, in a slow approach with some flaps, it is operating at high negative angle of attack, and that upside down airfoil comes in handy for getting the most elevator control power during the touchdown.

     

    BTW, the downforce from the tail makes the aircraft "heavier" and robs performance, that's why the Wright brothers used a canard, so the balancing smaller wing was also lifting. They didn't want to lose one ounce of performance.

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  4. Great thread guys! Where does your disdain for people who create the item end? Fly 200 degrees above the red lines? Overhaul the engine and leave out a few of those pesky parts?  Please don't let the fact that Rotax engineers built, tested, qualified, sold and supported 175,000 aircraft engines confuse your genius understanding of what they don't know. Just warn your passengers that you are smarter than them.

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  5. Change the engine design? Block off an existing system because you know better? Sure, and don't forget the self brain surgery.

    I am an engineer for an OEM, and constantly see the logic applied by darn smart people to out think the engineers who design, build and support their complex products. It is amusing. 

    I guarantee you more engines fail because the user didn't put enough oil in, as compared to the engines that fail because the oil injection didn't work. Remember, the prime cause of engine failure, by 3 to 1 factor, is that the pilot put too much air in the fuel tanks.

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  6. I put a fitting in for my extended range fuel tank, with a brass threaded fitting that miked out as 3/8" actual, and I used a 3/8" drill (and some small prayers). I covered the threads of the fitting with Permatex fuel tank repair epoxy, as a sealer, and it all worked perfectly. If I weren't so lazy, I'd put the fuel gauge tube there, too. Be sure the fitting fits properly when you fold and unfold, of course.

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  7. EDMO,

    that chart I found is in PSIA, and we think in PSI Gauge, so you have to remember that our gauge ignores the atmospheric 14.7 pis all around us. It is also on a log scale so it really sucks to make your point, but the answer is in there. Try using 32 psia, which is what a 17 psi cap gives you, and see that boiling occurs at about 255 deg F on the upper chart. at 15 psia, it occurs at 212 deg F.

    bpgraph.gif


  8. There is no requirement to get approval for "minor changes" and I assure you, VG's are not a major change. FAR 21.93 tells you what is important:

    (a) In addition to changes in type design specified in paragraph (b) of this section, changes in type design are classified as minor and major. A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes” (except as provided in paragraph (b) of this section)."

    Don't ask permission of the FAA, just log the VG install as a minor change in your maintenance manual and proceed.

     


  9. My experience in this area is pretty extensive. As a manufacturer test pilot for 30 years I made a living flying demos to show flight manual performance. The manufacturers all have to stand by the performance, and demonstrate it to the FAA (or an internal FAA designated engineer) so it has to be close to the truth.

    Most of the aircraft I have checked are pretty close, but since takeoff run is the sum of a dozen factors, it is the most easy measurement to get wrong. Think of the constituent parts: Prop condition and thrust, engine power production, rpm gauge accuracy, wing cleanliness, airspeed system calibration, tire pressure, surface hardness, grass depth. And with the slight climb angle, the biggest error could be the 50 reading, based on a cranky altimeter with 10' markings.

    You can bet that the flight manual is based on everything being factory new and perfect, and so the performance is ideal. If the prop has a few dings and an eroded leading edge that has been sanded for a few years, it can be easily 5% less than factory thrust. Run down each factor with similar degradation, and it is not hard to get big errors.

    I note that the dry grass run for a 150 at 1000', 75 degrees zero wind off dry grass would be 1660 feet over a 50' obstacle. Did it take them 3300 feet?

    150takeoff.jpg


  10. My Matco tail wheel, identical to yours, shimmied a bit at higher speeds just after touchdown until I tightened up the main pivot bolt a bit more than the instructions described. Since then I have had no shimmy events.

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  11. Hey, I love to take my Avid places. AT 82 knots, it is faster than driving, and if you like seeing things from the air, have at it! Next week, I intend to go to New York City, and then to Maryland, about 2.6 hours total flight time. 


  12. IMHO, on an Avid the tail wheel doesn't have the authority to stop a ground loop, so a lockable one isn't much of a cure. On youtube are a bunch of Ground Loop videos showing tail wheels sliding sideward, peeling the tire off the rim and even bending the tail mounting framing in the process.

    Best way to avoid a ground loop? "Happy Feet", lots and lots of pedal motion, small dithering that lets you react quickly to the initial yaw. I find using narrow, thin,  light shoes is important, since the Avid pedals were designed for Snow White's friends.

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