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Thread: Basic VFR Instruments

  1. #31
    rwanttaja's Avatar
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    Quote Originally Posted by Frank Giger View Post
    Since the Sport Pilot isn't acting as PIC, the door is open to perform a flight review in a Cessna 172, a Citabria, or a Cessna 152 (all of which I've done).
    Ditto... C172s and a Warrior, for me.

    First one (back in ~2006) was interesting. I was apparently the first SP the CFI had encountered.

    "You don't have a current medical?"

    "No, I'm flying as Sport Pilot, just need a BFR."

    "But a 172 isn't an LSA!"

    "Doesn't matter."

    The CFI had to talk to his boss...but we did fly the review.

    Ron Wanttaja

  2. #32
    I have a private... also tailwheel endorsement

    Just got my basic flight review in a Cessna 150....

    I fly my Experimental that fits LSA...So I don't need a medical...Just my drivers lic.

    Gotta Fly...

  3. #33

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    Quote Originally Posted by Airmutt View Post
    This device can also provide temperature, humidity, and serve as a magnetometer. Checkout Beliteís precision altimeter app.

    Itís all mute unless someone stands before the FAA/DAR and states my smart watch, phone, tablet etc is my altimeter, VSI, mag compass, and whatever and attempts to move the dial.
    I think you can get there with pressure-based altitude. The app is really cool. I know James (Belite) well (he's in town). They recently had a really bad fire, and I am not sure if they will be a Phoenix.

    I like where you're going with talking to the FAA/DAR. This is one reason I formed my own company. Why do we pay $30K for a landing gear actuator when an off the shelf one will do the same job for $300? The same is true for alternators and generators. We need to use what is commercially available from other industries and NOT manufacture 10/year to OEM specifications. There are simple ways around this!

    On a similar note, Transport Canada (TC) allows airplanes that are 30+ years old to be DE-certified and placed into an owner maintenance category (the standard AW is destroyed and a new owner maintenance one is made). It is like EAB, but it is NOT EAB. Under their regulations, the owner can do anything that they want to. I have attended several forums on Arduino-based instrument panels Ö very impressive! And inexpensive!

  4. #34
    Airmutt's Avatar
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    I heard about the fire; never a good thing. At least no one was injured. Didn’t know that they were that badly hurt. Hope they can hang in there and make a comeback.
    Dave Shaw
    EAA 67180 Lifetime
    Learn to Build, Build to Fly, Fly for Fun

  5. #35

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    Oddly enough, coming back on topic, why are we so excited about barometers in an age of GPS?

    I've noticed than when my barometer (altimeter) and the GPS altitudes disagree, it's within 100 feet (at most).

    Indeed, one would think that GPS would be adopted as the preferred method, with barometers as acceptable, or as a backup. We're relying on old tech because we always have.

    Frank "Adjust the altimeter to the field altitude" Giger.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  6. #36

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    Quote Originally Posted by Frank Giger View Post
    Oddly enough, coming back on topic, why are we so excited about barometers in an age of GPS?

    I've noticed than when my barometer (altimeter) and the GPS altitudes disagree, it's within 100 feet (at most).
    Barometers measure pressure (and force when multiplied by an area). If a pilot or autopilot were made to fly a hard GPS altitude (tape line altitude), the ride would be extremely rough, and the airplane structure would take a beating.

    When one sets their altimeter baro setting, they are correcting the pressure-based altitude to an approximate tapeline altitude (has to be within 50' for IFR flight). This is done so that airplanes flying at low altitude don't hit ground-based objects … and are separated vertically. At high altitude (class A), the baro is set to 29.92 so everyone flies with the same reference. Pressure fluctuations in the Flight Levels (FLs) are much greater.

    Ironically, when GPS first came out, the odds of a trans-oceanic mid-air went up greatly because now navigation systems were right on track (little navigation errors). This mandated RVSM (Reduced Vertical Separation Minima) … less errors allowed in the altimeter systems and autopilot control laws. Now the number of tracks has been increased so we can transport more people, more safely, in a smaller volume with higher safety (less odds of a mid-air) and along the shortest routes possible.

    Ron "hope this helps" Blum

  7. #37
    rwanttaja's Avatar
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    Quote Originally Posted by Frank Giger View Post
    Oddly enough, coming back on topic, why are we so excited about barometers in an age of GPS?

    I've noticed than when my barometer (altimeter) and the GPS altitudes disagree, it's within 100 feet (at most).

    Indeed, one would think that GPS would be adopted as the preferred method, with barometers as acceptable, or as a backup. We're relying on old tech because we always have.
    I dunno, Frank. Not trying to sound like a recruiter for the tinfoil-hat brigade, but that's a long stretch of technology that needs to work.

    You need a properly-running receiver, power for it, an antenna, a 20+ satellite constellation, a properly operating Ground Segment, and the Government's permission (i.e, they can shut down civilian users anytime).

    In addition both the good guys and the bad guys do things that affect usability; the bad guys have even lured drones off-course to snag them.

    Vishnu help us if they ever get a Nieuport that way. :-)

    In contrast, all a barometric altimeter needs is a bit of 1/4" rubber tube. Even if it breaks, you're off just a few hundred feet...not critical for most users. Similarly, setting the device to field elevation before takeoff is probably sufficient for most of GA.

    And if you require a barometric pressure-based altimeter as a backup, you're still going to run the rubber hose and calibrate it anyway. And it gives one more gauge that third-world airline captains will choose to ignore.

    Ron "I wear size 7 1/2" Wanttaja

  8. #38
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    Quote Originally Posted by Ron Blum View Post
    Barometers measure pressure (and force when multiplied by an area). If a pilot or autopilot were made to fly a hard GPS altitude (tape line altitude), the ride would be extremely rough, and the airplane structure would take a beating.
    Actually, I think most GPSs have an MSL output available. The hiking one I use in the Fly Baby does....

    They have a much fancier term than "MSL", of course.

    Ron "Luv them four-syllabobble words" Wanttaja

  9. #39

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    My thinking was that a big, big bunch of us are already using GPS for navigation - heck, it's used for IFR purposes, IIRC. It's pretty darned reliable within CONUS.

    It would seem that things like autopilots getting overly fussy is a software issue; and my little Nexus tablet is height above sea level.

    Now, I would never say that altimeters should be abandoned - I'm a card carrying member of the Steam Gauge Association, Anti-Glass Panel Chapter 192 - but I find it odd that a major fault of GPS is that it is too accurate.

    Even ADSB is taking the altimeter's word for granted, if I understand things.

    Granted, I don't have much of a dog in the hunt here - I'll never fly somewhere and have barometric pressures change enough to where being off adjustment matters. Heck, I rarely look at my altimeter, as the difference between 1,500 feet AGL and 2,500 AGL is fairly easy to suss out.*

    I'm thinking more about "going places" airplanes that wind up in controlled airspace and being told to fly at particular altitudes a long way away from where they started, or do things like fly over mountain ranges.

    * For about eight months both my ASI and altimeter were either inop or just telling blatant lies, and so rightfully ignored until I sorted out the right pitot/static locations. Indeed, in a lot of my flying videos it's very clear the ASI isn't connected to anything.

    Frank "Odd Ducks Fly East" Giger
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  10. #40

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    Quote Originally Posted by Frank Giger View Post
    It would seem that things like autopilots getting overly fussy is a software issue; and my little Nexus tablet is height above sea level.
    Frank: I did a poor job of explaining why one doesn't want to use GPS altitude for flight path control. GPS Lat/Long information is great for everyone … including autopilots (follow the pink line to your destination … one doesn't fly the route to the accuracy of the GPS). In addition, if one is only using GPS altitude for a rough estimate (1,500' to 2,500') that works, too. Autopilots in RVSM airspace have to maintain altitude within +/-60'.

    What doesn't work is when the air is moving up and down (pressure waves). I am bad at examples but here goes. The air has wave similar to the surfaces of lakes and oceans (both water and air are considered fluids). When we fly in turbulence, we try to keep the wings level but let the altitude change … so we don't overstress the airplane. Just as water waves go up and down (and the boat with it), the airplane wants to do the same. Now, anchor a boat with a rope/chain that is as short as possible (vertically straight down). As the waves come by, the boat and its occupants will get beat up (or break up) as the waves try to move the boat up and down. The same is true with airplanes in flight.

    Ron "Another try" Blum

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