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Building Tips and technical articles. => Building techniques => Topic started by: Dwayne Donnelly on April 10, 2022, 07:28:34 AM

Title: Well this is strange
Post by: Dwayne Donnelly on April 10, 2022, 07:28:34 AM
I have a plane with a SIG Super Chipmunk wing un-covered, I'm just aligning everything and ran the incidence meter the length of the wing, it has 1.5 degrees of negative at the tip when the plane is upright but when inverted it's dead on zero.  The leading and trailing edge looks straight so it's a head scratcher.  ??? n~
Title: Re: Well this is strange
Post by: Lauri Malila on April 10, 2022, 07:47:25 AM
Try turning the measuring device 180°, and see what the average is. L
Title: Re: Well this is strange
Post by: Ken Culbertson on April 10, 2022, 09:54:19 AM
Do you have another level you can put your meter on and check IT.  The meter may not show -0- when level.

Ken
Title: Re: Well this is strange
Post by: Lauri Malila on April 10, 2022, 10:00:04 AM
Do you have another level you can put your meter on and check IT.  The meter may not show -0- when level.

Ken

..that (and possible measuring hystetesis) is exactly why I adviced to check it both ways🤗 L
Title: Re: Well this is strange
Post by: Dan McEntee on April 10, 2022, 02:21:17 PM
I have a plane with a SIG Super Chipmunk wing un-covered, I'm just aligning everything and ran the incidence meter the length of the wing, it has 1.5 degrees of negative at the tip when the plane is upright but when inverted it's dead on zero.  The leading and trailing edge looks straight so it's a head scratcher.  ??? n~

     I notice that you say it is uncovered. The wind frame may be twisting just from the weight of the incidence meter. Any open panel wing will twist easy if it's not covered. If it is eyeball straight it may be just fine. Get it covered, shrunk, and at least a coat of dope or two and then recheck.

  Type at you later,
   Dan McEntee
Title: Re: Well this is strange
Post by: Craig Beswick on April 10, 2022, 04:02:14 PM
As previously suggested I would check your level , for level, first!

Craig