cdarza Posted January 27, 2014 Report Share Posted January 27, 2014 Recently had some airspeed issues on the Dynon. I was climbing out at 80 kts whilst the GPS ground speed was indicating 60kts. (this wasnt a windy day) Just by the angle of attack and my RPM takeoff setting I knew i was not doing 80kts climbing at 800ft/min. Same issue on my landing approach. Dynon was indicating around 80 - 85 kts on my typical 60kts approach. Long story short - after checking the tubes/hoses/ connections - i finally remembered the static port. On the belly on CTSW's. Somehow, over the four years and 500hours of flying my CTSW, i had never inspected the opening to the static port. Duh moment. Found partial blockage. So, to those that may have not checked recently - please do. I can only imagine the trouble i would have got myself into had I followed the airspeed indicator 100% . I could have stalled at indicated 60kts !! GPS ground speed and knowledge of winds would be a indication of your actual estimated airspeed. Link to comment Share on other sites More sharing options...
rookie Posted January 27, 2014 Report Share Posted January 27, 2014 I had a similar experience in the opposite direction, a leak in the pitot line indicated I was slowing down while the sight, sound and feel of the plane felt normal. GPS confirmed my seat of the pants. Normally wouldn't have been a concern except it happened on base to final turn and took few seconds to figure out what was going on. Link to comment Share on other sites More sharing options...
Fly Boss Posted May 8, 2016 Report Share Posted May 8, 2016 Recently had some airspeed issues on the Dynon. I was climbing out at 80 kts whilst the GPS ground speed was indicating 60kts. (this wasnt a windy day) Just by the angle of attack and my RPM takeoff setting I knew i was not doing 80kts climbing at 800ft/min. Same issue on my landing approach. Dynon was indicating around 80 - 85 kts on my typical 60kts approach. Long story short - after checking the tubes/hoses/ connections - i finally remembered the static port. On the belly on CTSW's. Somehow, over the four years and 500hours of flying my CTSW, i had never inspected the opening to the static port. Duh moment. Found partial blockage. So, to those that may have not checked recently - please do. I can only imagine the trouble i would have got myself into had I followed the airspeed indicator 100% . I could have stalled at indicated 60kts !! GPS ground speed and knowledge of winds would be a indication of your actual estimated airspeed. How do you remove the static assembly under the belly of the CTLS plane? If I really want to blow it out, the small hole is not going to allow debris to successfully exit. I can't determine if it is screwed on or what. Link to comment Share on other sites More sharing options...
Anticept Posted May 8, 2016 Report Share Posted May 8, 2016 You blow it out from the line inside of the cockpit. Failing that, it depends on what the blockage is. Link to comment Share on other sites More sharing options...
Anticept Posted May 8, 2016 Report Share Posted May 8, 2016 It's called an air dam, and it's used to stabilize the static pressure behind it. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted May 9, 2016 Report Share Posted May 9, 2016 It's called an air dam, and it's used to stabilize the static pressure behind it. Weirdly, the dam seems like it would create higher-than-ambient pressure on the static port if faced rearward, and lower-than-ambient pressure if faced forward as designed. Neither would seem to be ideal, but it seems to work fine. Curious why a dam is needed at all since many airplanes like Cessnas have unshielded static ports right in the airflow with no issues. Is this just a case of FD over-thinking a "problem" that doesn't really exist? Link to comment Share on other sites More sharing options...
Anticept Posted May 9, 2016 Report Share Posted May 9, 2016 It's a complicated problem. Getting into boundary layers requires some real voodoo math to work with.In large aircraft, there is actually a spec in fractions of a millimeter on how thick the paint can be around the static ports, especially those that participate in RVSM.Anyways, yes it can lower the static pressure slightly, but also stabilizes it, but I am sure that was accounted for in the airspeed readings. They are in calibrated readouts, after all! Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted May 9, 2016 Report Share Posted May 9, 2016 I think the way the dam works on a CT static port is 'whatever works'. If you don't like the result then reverse it and if you don't get an improvement put it back as it was. Link to comment Share on other sites More sharing options...
Fly Boss Posted May 10, 2016 Report Share Posted May 10, 2016 So, having taken all the lines off and blown them out completely, the system is back together and working as it should. Didn't hurt to tighten some of the connections either. Danny Link to comment Share on other sites More sharing options...
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