Avid Flyer Angle of Incidence

9 posts in this topic

Posted

Would someone help me understand a few things about angle of incidence?

Quoted from Wikipedia:

"On fixed-wing aircraft, the angle of incidence (sometimes referred to as the mounting angle) is the angle between the chord line of the wing where the wing is mounted to the fuselage, and a reference axis along the fuselage (often the direction of minimum drag, or where applicable, the longitudinal axis)."

 

Please tell me how to determine the reference axis of the Avid MKIV fuselage and the proper way to determine the chord line of my aerobatic wing.

 

Thanks in advance!

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Posted


There was a thread about this a few years I'll see if I can find it.

 

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Posted

Click on this link and read through it it may or may not help you but is interesting.

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Posted

Thanks T-Jay. I read that one before. It’s a great thread, But unfortunately it doesn’t answer my queries. 

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Posted

Super, the wing incidence/fuselage angle procedure is in the Build Book, which is in http://avidfoxflyers.com/index.php?/topic/4220-avid-mk-iv-build-manual/

See Sec III, chap 8 for how to level the fuselage, and then Sec VIII, Chap 6 for how to find and set the wing angle. This will set the angle of incidence to the "factory" (ahem!) setting.

I took the liberty of snatching them here:

 

level fuselage.jpg

wings 1.jpg

wings 2.jpg

wings 3.jpg

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Posted

This is helpful. Does anyone know what airfoils (Naca?) are used for the 2 different mkiv wing ribs (speedwing and stol profiles)? Also, does anyone what Dean Wilson specified for the water line on the mkiv speedwing?

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Posted (edited)

Supermotive, I am pretty sure the airfoils are NOT standard, one member a while back even published the airfoil coordinates as a result.

I have in my files an old, old build book that defines the wing construction for the MK IV and the Speedwing, and the wing incidence angle method for the speedwing is not mentioned, so it might be the same method as the MK IV. Below is the manual section defining the wings, the addendum pages 2A-1 thru 2A-5, which starts off "Speed Wings are constructed exactly the same as standard wings, except for the changes identified in this addition to the manual."

speed wing 1.jpg

speed wing 2.jpg

speed wing 3.jpg

speed wing 4.jpg

speed wing 5.jpg

fuselage leveling.jpg

Edited by nlappos
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Posted

Are you just wanting to measure the angle of incidence that your plane was built to? The reference line you seek is the bottom of the door opening (sill).  To establish a parallel chord line for the wing, the front spar is 2 1/2" so the center point would be 1 1/4" and the thickness at the trailing edge assuming it is 1/4" ( you make the actual measurement of your wing) then subtract one half of that measurement from the front measurement in this example 1 1/4" - 1/8" = 1 1/8".  So with a straightedge attach a 1 1/8" block to the trailing edge end and place the straightedge spanning forward to the spar.  With the aircraft leveled to the door sill now measured the angle across the straightedge at the wing root with your smart level.  

Hope this is what you are looking for, if not please explane what you are trying to do so that your question maybe answered correctly.

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Posted

That was exactly what I was looking for wypaul. Thanks!! 

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