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Re: Pitot-Static system...?
Originally Posted by
Homer Landreth
My 1951 pacer has the "upside down F" waaaay out there on the wing, but my 1959 TriPacer has the static ports on the belly. So appearance makes you wonder why in the ensuing 8 years the static source was moved from what appears to be a considerably cleaner airflow point out on the wing to an area seemingly ripe with airflow turbulence potential from Landing Gear structure, and Prop Wash, and airplane motion from the likes of Vertical Vortexes. If I was in the design review meeting when that idea was first introduced I would have probably been inclined at first to get up and walk out, so someone must have had to make a really good presentation to get that idea sold.
And that is where what appears to be better isn't in my opinion. The static ports on the belly seem to be more accurate that the one on the pitot. Tuft your wing on the bottom side around that pitot and see what it does in slow flight with the flaps down. Very bad location in my opinion but that is what a lot of them were certified with. I agree with you on the "approved data", need something to substantiate your actions if it is certified.
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Re: Pitot-Static system...?
Good to know the process. Kinda figured the boot cowl wasn't a good location like it is on a Cessna.. static port is at a right angle to airflow..not so with the slight angle on the Pacer/Tripacer boot cowl....always have felt resorting to name calling is synonymous with...um...defeat.
Sent from my iPad using Tapatalk
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Re: Pitot-Static system...?
Wow, lots of interesting posts to my initial question. Hearing from you all that there are a variety of static "systems" out there my take on this resonates with Steve, Homer and Gilberts comments and is likewise rooted in my engineering experience that the original designers, and flight qualification process approved the original system to some standard of accuracy and reliability in the day. They based their design qualification approvals upon test data so, I'm going to try to restore my '56 PA22-150 static system to original specs. My plane has what appears to be the original belly static system but it isn't attached at the forward end to any of the static port carrying gauges in the panel. When I inspected the upside-down U area on the floor behind the baggage comp, I can see the two small holes that were originally poked in my recovered TP (circa 1989), but they have been doped over at some point. Does anyone know the correct diameter for these original small holes? And, should there be some sealing of the small diameter copper(?) tubing to the Ceconite fabric at the interface, or leave an air gap? Thanks.
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Re: Pitot-Static system...?
For what its worth, my 1960 Pacer has the static ports on the belly and goes through IFR certification every 24 month. I also fly it in the ATC system frequently and I don't have controllers telling me my altitude is off (unless it is really off). As far as I'm concerned, the system works pretty good.
Juergen
Pacer N3342Z
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Re: Pitot-Static system...?
Repeating the questions: Does anyone know the diameter of the small perforations in the belly fabric of the static system inlet? And, should the end of the upside-down-U be sealed to the fabric or not? Thanks for the help.
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Re: Pitot-Static system...?
Disregard my questions and last post! I see this string really is a rehash, as most probably are now and Steve connected the old and new together, thanks. I've got drawing 14498 printing out now with all the detail of the upside down U! Thanks
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Re: Pitot-Static system...?
Originally Posted by
Subsonic
Repeating the questions: Does anyone know the diameter of the small perforations in the belly fabric of the static system inlet? And, should the end of the upside-down-U be sealed to the fabric or not? Thanks for the help.
Hole diameter is not critical as it is a pressure port with no air movement, hopefully. Just use a hot needle or small soldering iron tip to melt thru the fabric. Don't leave a ridge on the outside that will disturb the air flow.
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Re: Pitot-Static system...?
Very well! Thanks Gilbert.
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Re: Pitot-Static system...?
Hey, folks. Looking for some more help...this time with my static system, or lack there of. I'm going down to the big city next week for the float change and I can also get my pitot static check done in the same trip. It's only 68 odd airmiles, but as the resort season starts to ramp up, I find it harder and harder to get away.
That said, I'm looking to track down drawing 14498. I've got a '59 PA-22/20 Sn: 22-6587. Far as I can tell I should have the u-shaped set up aft of the baggage compartment. I've found the parts list for what I'll need for materials, but the station that will do the pitot static check would like some more documentation to get everything squared away proper.
Might be a silly question, but where do I purchase this drawing cd folks keep referring to? Maybe someone could sort me out with drawing 14498 until my cd arrives? considering the present rate of me finding creative solutions to the TCDS, I'll definitely need it.
Thanks much!
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