Angle of incidence question

dshly · Apr 05, 2002, 10:47 AM

Where do you measure the angle of incidence on a flat bottom wing?? I have Great Planes laser incidence meter and it appears to me that it measures the chord from a point higher up on the leading edge than what the chord across the bottom of the wing would be. This is because the 90 degree angle bracket of the meter sets around the curved leading edge, raising the line being measured up 1/4 to 3/8 inch above the flat bottom projected line.

Hope I've made myself clear. Thanks for help

Sparky Paul · Apr 05, 2002, 11:16 AM

Your wing isn't a true flat bottom. Most aren't.
It is generally done by presuming the flattish portion aft of the spar is the index for the angle the wing sits on the fuselage, for those planes where the true orientation isn't specified..
Like this:

Sparky Paul · Apr 05, 2002, 01:17 PM

Flat bottom...
Incidence...

Gary Retterbush · Apr 05, 2002, 02:31 PM

Like Sparky said.

Just let the GP Laser do it's thing. It will be correct.

rsieminski · Apr 06, 2002, 01:16 AM

Sparky Paul,
Dude, you are a wealth of information with a ton of resources! I am always impressed with your replies; clean, concise, easy to understand, and usually with visual aids. You are a king.
--Rick

dshly · Apr 06, 2002, 12:25 PM

Thanks for help. Used the laser meter and it looks right. Apparently the chord is the important thing, regardless of the flatness of the wing.

Sparky Paul · Apr 06, 2002, 08:14 PM

Rick the praise is appreciated! <blush>

Apr 05, 2002, 10:47 AM	#1
dshly Registered User Join Date: Oct 2000 Location: Omaha Millard, Nebraska, United States Posts: 87	Angle of incidence question Where do you measure the angle of incidence on a flat bottom wing?? I have Great Planes laser incidence meter and it appears to me that it measures the chord from a point higher up on the leading edge than what the chord across the bottom of the wing would be. This is because the 90 degree angle bracket of the meter sets around the curved leading edge, raising the line being measured up 1/4 to 3/8 inch above the flat bottom projected line. Hope I've made myself clear. Thanks for help

Apr 05, 2002, 11:16 AM	#2
Sparky Paul Ascended Master Join Date: Oct 2000 Location: Palmdale, CA Posts: 10,520	Your wing isn't a true flat bottom. Most aren't. It is generally done by presuming the flattish portion aft of the spar is the index for the angle the wing sits on the fuselage, for those planes where the true orientation isn't specified.. Like this: Attached Thumbnails 52.6 KB · Views: 260

Apr 05, 2002, 01:17 PM	#3
Sparky Paul Ascended Master Join Date: Oct 2000 Location: Palmdale, CA Posts: 10,520	Flat bottom... Incidence... Attached Thumbnails 47.3 KB · Views: 252

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Apr 05, 2002, 02:31 PM	#4
Gary Retterbush I "plant" trees (balsa) Join Date: Jan 2002 Location: Eisenschmitt, Germany Posts: 776	Like Sparky said. Just let the GP Laser do it's thing. It will be correct.

Apr 06, 2002, 01:16 AM	#5
rsieminski Registered User Join Date: Oct 2001 Location: Florida Posts: 178	Sparky Paul, Dude, you are a wealth of information with a ton of resources! I am always impressed with your replies; clean, concise, easy to understand, and usually with visual aids. You are a king. --Rick

Apr 06, 2002, 12:25 PM	#6
dshly Registered User Join Date: Oct 2000 Location: Omaha Millard, Nebraska, United States Posts: 87	Thanks for help. Used the laser meter and it looks right. Apparently the chord is the important thing, regardless of the flatness of the wing.

Apr 06, 2002, 08:14 PM	#7
Sparky Paul Ascended Master Join Date: Oct 2000 Location: Palmdale, CA Posts: 10,520	Rick the praise is appreciated! <blush>