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Thread: Not mass balanced & cable failure

  1. #21
    David Pavlich's Avatar
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    Steve...reading the above post, it almost sounds like you're trying to talk yourself out of flying. Undetected fatigue, cable failure, etc. These kinds of thing have been concerns since man became mechanised. Every time you get into your car, there's a chance that you could have a flat tire at high speed while going around a turn and end up in the woods.

    All we can do is inspect and follow the maintenance recommendations set down by the FAA, Piper, Beach, Ford, GM and so on. Or, we can wake up and decide to stay in the house and lower the risk factor to near zero.

    David

  2. #22
    steveinindy's Avatar
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    Or, we can wake up and decide to stay in the house and lower the risk factor to near zero.
    Actually the odds of being hurt in your own home are pretty high. If that's not enough, take a look at the risk of complications (blood clots, etc) that come with not even bothering getting out of bed!
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  3. #23
    David Pavlich's Avatar
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    Quote Originally Posted by steveinindy View Post
    Actually the odds of being hurt in your own home are pretty high. If that's not enough, take a look at the risk of complications (blood clots, etc) that come with not even bothering getting out of bed!
    Like I said, near 0.

    David

  4. #24

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    Quote Originally Posted by steveinindy View Post
    Actually the odds of being hurt in your own home are pretty high. If that's not enough, take a look at the risk of complications (blood clots, etc) that come with not even bothering getting out of bed!
    Btw, you can also have blood clots from too much time in the left seat

    Guys, there is no need to tell me how safe is to fly, even if I wanted to leave aviation, I couldn't. It's in my blood, I think you know the feeling

    This wanted to be more like a technical discussion, not one which takes care about my worries.

    As I said, I think it's worth it to know in advance what to expect in an emergency and how to deal with it, even if it's one of the rare. I prepare to be a lifetime in aviation, I think it worths to know even some advanced things which are not usually adressed during normal training.

  5. #25

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    Flutter was a hot topic among fellow builders a few years ago. There was a string of in flight break-ups. I won't name names. We had our "flutter deniers" but NTSB proved flutter in the end. My friend and co-worker knew a retired USAF Aerodynamacist in our area. We took my dwgs for a show and tell. Got great advice. He finished with "If the CG of the control surface is ahead of the hinge, flutter is impossible."

    If you want to see real counter weights, go find a KitFox and check out the flaperons. KitFox is the son of an Avid and so are EuroFox, Aerotrek and Appolo. Excelent safety records. I know a couple of guys with kitfoxs.

    A couple of ultralights had fatal flutter break-ups in the past. One was a US plagerized French design that deleted the aileron flutter protection. The French had no problems, only the US version. If you look at pictures of Ercoupes taken in the 40s & 50s, you will notice aileron balance weights. The FAA allowed their removal (don't know when) A wing came apart about 5 years ago and killed two. The resulting AD still lets you remove them. NTSB said flutter.

    I was building a Thorp T-18 in the late 60s. Mid 69, one came apart in the air and killed two. November 69, a solo pilot in CA had what seemed to be an explosion at 160-165 KTS. He got it on the ground. Miracle! The (snail mail) newsletter pictures showed a pretty much destroyed stabilator. The rivet seam on the top R. longeron was sheared fwd to the cockpit. Point of interest: John Thorp designed the first PA-28 stabilator and it also went on the T-18. FAA & Thorp found accumulated slop in two bearings of the cockpit to stabilator control rod linkage. Enough to cause flutter. I got dwg revisions dated Feb,70 in the mail.

    I learned that flutter is related to TAS more than IAS/CAS. I was looking at the POH for a glider and and found charts for TAS to IAS and IAS to TAS. Kind of like a helo where Vne is reduced as you climb.

    If you want a free resource on flutter related data, I have a Yahoo group for you. The "files" area is a gold mine. Used to be mucho old NACA reports related to the subject.

    http://groups.yahoo.com/group/ZBAG/

    There was one report from the 40s-50s where they put full size wings/tails in a wind tunnel and tested to destruction. Yeah, I know, real scientist don't do that to wind tunnels. Read the report. They recorded freqs in the 600-800 CPM remaining constant with changing AS, as I recall. Only changing with the size/ mass of the panel being tested. My take is: Don't let anybody tell you that flutter is a silent killer. In fact, if you dig into the many NTSB reports herein you will find more than one eyewitness reports that state that they looked up only when they heard what they thought was the pilot jazzing the engine. Could this be the sound of flutter?This was followed by what they called an explosion. See how many you can count that were in the traffic pattern. Most of these NTSB reports have the annexes that are hard to get.

    Bob

  6. #26
    steveinindy's Avatar
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    Btw, you can also have blood clots from too much time in the left seat
    Only if you're not using your legs to control the rudder. Moving your leg muscles helps to minimize stasis (pooling) of the blood in the venous beds of the legs which contributes to blood clots. Staying hydrated also helps. Using oxygen at lower than normally considered altitudes might also help since hypoxia (even of a low-grade nature) is a pretty well established trigger for the clotting cascade.

    If you can't tell I am a physiology geek.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  7. #27

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    Bob, great info, I really appreciate!

    Quote Originally Posted by steveinindy View Post
    If you can't tell I am a physiology geek.
    You really are

  8. #28
    David Pavlich's Avatar
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    Maybe you've seen this already. Very timely:

    https://www2.gotomeeting.com/register/980209042

    David

  9. #29

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    I sure am glad my little Nieuport has push rods for aileron and elevator control.

    And that it won't go faster than 60 mph.

    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  10. #30

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    Trim tab flutter is probably more likely ( I think)because of small size and lack of balance. A small slop in twin tab has more effect. The modern FAR 23 requires "irreversible " control system for trim tab.
    But old regs allowed Aeroncas and others with reversible cables. Cubs don't have tabs.

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