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#11
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"Stan Gosnell" wrote in message ... "Wyatt Emmerich" wrote in news The altimeter readings were all correct on the flight. The transponder reported accurately and center never had a problem with my altitude. So it seems to me, the static system must be correct. A loose connection in the ram air system could give erroneous airspeed readings while giving correct altimeter readings, as could a partial obstruction. I've seen water in the pitot system give this error also, which is really a partial obstruction. Just a comment: We were required to do a leak test after opening a pitot or static line for whatever reason. Eventually water drain fittings were removed from this required list but that seemed to me at the time to be a mistake since those o-rings were especially prone to rotting out. O-ring quality improvement seemed to solve that. JK (expecting a mud wasp comment from tarver) |
#12
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"John R. Copeland" wrote in message ... "Robert Moore" wrote in message . 6... "Maule Driver" wrote That's glider stuff. You tap it instead of allowing engine vibration to do it. In the B-707, the altimeter had a built-in altimeter-tapper at about two cps. This was required equipment in the event that the electronic altimeter correction failed or was turned off. Turning the correction off, turned on the tapper. Bob Moore The drum-and-pointer altimeter in my C340 has an internal vibrator. I don't know its frequency, but it's much higher than 2 cps. When it's not vibrating, there's a big hang-up every 1000 feet, at the point where the drum reading indexes to its next value. Engine vibration is insufficient to keep it free. ---JRC--- Us old-timers got to see the 'system' evolve from a knuckle rap to an external strap on vibrator and eventually the built in. :-) Looking at a 777 diagram, it seems to have AnalogDigitalModules located right at the pitot tubes or static port pairs and no need to rap or vibrate anything. Ain't modern technology wonderful? JK |
#13
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Shifting winds and tailwinds should have no effect on your airspeed
indicator. The airspeed indicator is a static instrument. Dirt or something could have been blown into there during the static check. |
#14
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"Jim Knoyle" wrote in message ... Just a comment: "Tarver Engineering" wrote: "Gord Beaman" wrote in message .. . "Jim Knoyle" wrote: Hang on here a second now Jim, you still need two samples. As Dan says you need 'static pressure' to read the altitude from and you need 'pitot pressure' (ram air pressure) as well as the static pressure to derive the airspeed reading from. Sounds like you're saying that you can read 'both' from just the 'ram air pressure' alone. Or did I misunderstand you? Jim has finally figued out what a pitot tube is, but somehow he still wants to be correct in his archive troll. It is a great paradox. I know...ain't life a bitch John -- -Gord. |
#15
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"C J Campbell" wrote
Shifting winds and tailwinds should have no effect on your airspeed indicator. As opposed to "indicated airspeed"? How does one tell the difference? Bob Moore |
#16
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In article ,
"C J Campbell" wrote: Shifting winds and tailwinds should have no effect on your airspeed indicator. They would while in the early part of the takeoff roll...it will take "longer" to notice the airspeed alive when you have a tailwind...GS would have to exceed the tailwind before you'd get any indication. -- Dale L. Falk There is nothing - absolutely nothing - half so much worth doing as simply messing around with airplanes. http://home.gci.net/~sncdfalk/flying.html |
#17
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"Wyatt Emmerich" wrote
I had a my two-year transponder/static system check while visiting my mother in San Antonio. When I departed, I noticed the airspeed didn't come up like it should. I attributed this to shifting winds and assumed I had a slight tailwind. Then in cruise, I did my normal operating performance check. My IAS was about 30 knots low, but my groundspeed was normal. I tapped on the airspeed indicator and it gained six knots. Question #1: How would a transponder/static check screw up my airspeed? Was this just coincidence? In my experience, taking the airplane to the shop for something and having it come out with something broken that worked just fine previously is more the norm than the exception. This is why I advise people who are not going to be filing IFR to not get a pitot-static check - not only does it cost money, but usually something winds up broken. Most likely, your problem is that the pitot line was opened in order to attach a calibrated pressure source, and in the process either old dirt was disturbed or new dirt was introduced. Now it's in the line or the ASI. Question #2: How do you check accuracy of an airspeed indicator? By making up your own calibrated pressure source. Google rec.aviation.homebuilt - there was a thread about this very thing there in the last few months. A calibrated source is easy - all it takes is some nylon tubing, a liquid of known density (like water), and a ruler. Question #3: How long should you go before replacing an airspeed indicator? Normally, they don't wear out. If you don't let sloppy workmen get dirt into it, it will last decades. Michael |
#18
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"Michael" wrote in message om... "Wyatt Emmerich" wrote I had a my two-year transponder/static system check while visiting my mother in San Antonio. When I departed, I noticed the airspeed didn't come up like it should. I attributed this to shifting winds and assumed I had a slight tailwind. Then in cruise, I did my normal operating performance check. My IAS was about 30 knots low, but my groundspeed was normal. I tapped on the airspeed indicator and it gained six knots. Question #1: How would a transponder/static check screw up my airspeed? Was this just coincidence? In my experience, taking the airplane to the shop for something and having it come out with something broken that worked just fine previously is more the norm than the exception. Frankly, Michael, you seem to hang out with a rough crowd. You keep saying that the flight instructors are all incompetent, as are all the pilots, the FAA, the mechanics, and everybody else. Are you the only person in the whole world who is able to do his job? If so, then we should all take out a big insurance policy on you. We will need it if anything happens to you and the world stops turning as a result. :-) |
#19
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"C J Campbell" wrote
Frankly, Michael, you seem to hang out with a rough crowd. You keep saying that the flight instructors are all incompetent, as are all the pilots, the FAA, the mechanics, and everybody else. That's fascinating. You have google available - please cite one place where I said that. If the word "all" is not included, it's not a cite. Don't have one? Didn't think so. Are you the only person in the whole world who is able to do his job? Nah. Lots are. For example, note the list of highly qualified 10,000+ hour instructors who trained me. BTW, none of them include non-pilot time in that total. There are even competent people in the FAA, much as it pains me to say it. I've only ever met one, but I have many friends in the airline business who claim to have met many, and I have no reason to doubt their veracity. But there is something special about GA. It's not really an industry - it's more like a disease. Most of us involved in it know full well that it's not a viable way to make a living. Most, but not all. How do you make a small fortune in GA? Start with a large one, and know when to quit. It's a cliche, but it didn't get to be a cliche by being wrong. Once in a while someone manages to find a specialized niche and do well with it (a few of them post here - Jim Weir and Paul Sanchez are good examples), but most people who decide to make a living in GA fall into the otherwise unemployable category. I've known many excellent A&P mechanics. Few of them were interested in doing general retail GA work for a living. One ran a specialty restoration shop, one was a retired director of maintenance for a major airline, one was an airline pilot who ran an FBO one the side, and a few were owners who got the rating to be able to work on their own stuff and help friends. Most of the really good A&P mechanics who actually want to make a living of it wind up with the airlines or the local automobile dealership. More money, fewer hassles. Can't blame them, really. Very few owners in GA will pay what it costs to do things right, and most of the ones who understand what doing it right means in the first place are going to do it themselves. The ones who are left, well, a handful are there because they really like messing around with little airplanes, but most are not otherwise employable. What does doing it right mean, anyway? Realize that most of these planes are old, and have systems that have been patched and modified many times, sometimes incompetently, and were often poorly designed in the first place. As a result, they are fragile, and must be handled with care. Care means time. If a guy advertises a pitot/static/transponder check for under $200, you know something is wrong. Think about it - he has an investment in equipment and labor at least as great as an automotive safety/emissions inspection station. Those guys inspect your car in 20 minutes and charge $40 to do it (this is Houston-specific, but I doubt it's much different in other major cities). That means the guy had to be able to pull and check your transponder, encoder, ASI and altimeter and do your paperwork in well under two hours to make it all work out. Is there time to do all that CAREFULLY in less than two hours? Of course not. So he either has to 'find' a problem and charge you to fix it, or he has to rush the job and most likely break something. But if he was up-front and charged what it really cost to do it right, he would lose business to the lower-dollar competitors. Pilots are notoriously cheap. Someone who is competent and honest will soon get disgusted with this and leave the industry, so mostly we have the people who didn't get disgusted and stayed. I've known many excellent CFI's. These included airline and military pilots, aerobatic competitors, and even some non-professional pilots who had flown for years, accumulated many hundreds of hours of experience flying all over the country, and had a desire to pass on their knowledge and experience. Few of them were interested in doing retail instruction, and none were interested in instructing full-time. They would teach because they enjoyed teaching, when they felt like it. Of course with that kind of attitude, they weren't too popular with FBO's that were trying to run a business (not a hobby operation). Most active instructors are building time for the airlines, and are not otherwise employable in aviation. Most of them leave as soon as they can get any other aviation job. The ones who display a willingness to learn and a reasonable clue level get hired early (connections also help) so a high-hours full-time CFI is actually a red flag. You have to ask yourself WHY he is still a full-time CFI. It could be skeletons in the closet (I knew a good instructor who couldn't get hired until the incident where he buzzed boats on a lake went off his record) or immigration issues, but more likely it's because the professional pilots doing the hiring can spot him as a loser from a mile away and don't want him in their fleet. Interestingly, I have known VERY few bad/incompetent glider instructors and even the very worst I've encountered were above average for power instructors in terms of skill, knowledge, and experience. There is a simple reason - glider instruction is not a stepping stone to the airlines. As a result, the average glider instructor is an accomplished professional in his field. That field might be aviation, or it might not. Michael |
#20
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"Tarver Engineering" wrote in message ...
"Jim Knoyle" wrote in message ... Just a comment: "Tarver Engineering" wrote: "Gord Beaman" wrote in message .. . "Jim Knoyle" wrote: Hang on here a second now Jim, you still need two samples. As Dan says you need 'static pressure' to read the altitude from and you need 'pitot pressure' (ram air pressure) as well as the static pressure to derive the airspeed reading from. Sounds like you're saying that you can read 'both' from just the 'ram air pressure' alone. Or did I misunderstand you? Jim has finally figued out what a pitot tube is, but somehow he still wants to be correct in his archive troll. It is a great paradox. I know...ain't life a bitch John pathetic splaps boy. your *one* sample of trying to bolster your credibility is a snip from the orginal post from the orginal thread, which everyone knows and your feeble attempt at gaining any degree of credibility leaves you looking like an even greater ******. very poor splaps boy, very poor. your dissertation on "negative cabin pressurization" has more inginuity. |
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