Original Posted By: "Christian Bobka"
Jack,Are you sure that your static tube did not break off your pitot tube? Onthe 140 I fly all the time, it has a nice pitot static setup that comes downout of wing (the fabric wing) and the pitot and static are siamesedtogether.The wing probably has the lowest pressure inside it in the entire ship.It seems one could make a nice pitot and static setup from some coppertubing. I am sure it is covered in Bingelis somewhere. In my opinion, theoutboard wing location down and forward a foot or so is the best. If thestatic tube has but two holes in it, one left and one right with themlocated on the horizontal axis, any slipping will be nulled out by thepressure going up on the windward side and the pressure dropping on theleeward side and the net will still be as close to the true static pressureas you can get.Finding a spot on the fuselage that is proper would take some sensitiveinstrumentation.My tcraft had open static ports to the inside of the cabin and I flew slowerthan indicated and I always knew I was lower than the altimeter said butthat is ok if you are under class B.chris bobka________________________________________________________________________________
Pietenpol-List: Pitot tube and static tube
RE: Pietenpol-List: Pitot tube and static tube
Original Posted By: Fisherman Caye
Jack,Are you sure that your static tube did not break off your pitot tube? Onthe 140 I fly all the time, it has a nice pitot static setup that comes downout of wing (the fabric wing) and the pitot and static are siamesedtogether.chris bobkaChris, I'm not sure. According to the logs, that plane has had a hard life(been groundlooped three times, over on its back at least once). It is anearly 1947 model and I know that Cessna experimented around with the staticport placement before they finally settled on a location on either side ofthe fuselage. This one has metallized wings and it's possible that whoeverdid the metallizing just cut off the static line and crimped it as Idescribed, although I've seen some reference in the Cessna 140 discussionforums that late 1946 and early 1947 120's and 140's had the setup I have,with the static line ported inside the left wing. It seems fairly accurateat cruise - my airspeed in usually accurate within a couple of mph asverified by GPS on light wind days. I do know that it indicates lower thanit should at high angles of attack (it indicates 40 mph at stall with flapswhen it should be more like 45), but that is probably due more to pitoterrors than static errors. If I went to the trouble to bevel the inside ofthe pitot tube opening I could probably eliminate those errors.Jack________________________________________________________________________________Date: 6 Feb 2002 05:44:13 -0800
Jack,Are you sure that your static tube did not break off your pitot tube? Onthe 140 I fly all the time, it has a nice pitot static setup that comes downout of wing (the fabric wing) and the pitot and static are siamesedtogether.chris bobkaChris, I'm not sure. According to the logs, that plane has had a hard life(been groundlooped three times, over on its back at least once). It is anearly 1947 model and I know that Cessna experimented around with the staticport placement before they finally settled on a location on either side ofthe fuselage. This one has metallized wings and it's possible that whoeverdid the metallizing just cut off the static line and crimped it as Idescribed, although I've seen some reference in the Cessna 140 discussionforums that late 1946 and early 1947 120's and 140's had the setup I have,with the static line ported inside the left wing. It seems fairly accurateat cruise - my airspeed in usually accurate within a couple of mph asverified by GPS on light wind days. I do know that it indicates lower thanit should at high angles of attack (it indicates 40 mph at stall with flapswhen it should be more like 45), but that is probably due more to pitoterrors than static errors. If I went to the trouble to bevel the inside ofthe pitot tube opening I could probably eliminate those errors.Jack________________________________________________________________________________Date: 6 Feb 2002 05:44:13 -0800
RE: Pietenpol-List: mon, the eggheads go wild on the internet
Original Posted By: Fisherman Caye