

Calculating Aspect Ratio of Wing
Name: Thomas
Status: student
Grade: 68
Location: CA
Country: USA
Date: Fall 2013
Question:
If the cord changes throughout the wing, than how do I calculate the aspect ratio?
Replies:
Thomas
I found this explanation at the URL:
http://www.pilotfriend.com/training/flight_training/aero/aspect.htm
This article says:
"aspect ratioAspect ratio is the wing span divided by the mean wing chord. An aircraft with a rectangular wing of area 12 mÂ² might have a wing span of 8 m and wing chord of 1.5 m. In this case the aspect ratio is 5.33. If the span was 12 m and the chord 1 m then the aspect ratio would be 12. However because wings may have varied plan forms it is usual to calculate aspect ratio as:
Aspect ratio = wing spanÂ² / wing area "
You can get more information by reading the article at the above URL.
By the way, I went to http://www.google.com and searched for " calculating airplane wing aspect ratio"
and found a whole lot more interesting articles on this subject.
Sincere regards,
Mike Stewart
Hi Thomas,
For wings that taper, the formula for aspect ratio is the wing span squared divided by the wing area. For the case of a constant chord wing, you can see this equation reduces to span divided by chord.
John C Strong
Thomas 
The aspect ratio is calculated using the MAC  Mean Aerodynamic Chord  the average chord of the wing. One way of getting the MAC is to take the area of the wing and divide it by the wing span.
Larry Krengel
Hi Thomas,
Because a typical wing chord (as you have stated) varies (or tapers)
from root to tip, a wing's aspect ratio is measured by dividing the
square of the wingspan, by the area of the wing as viewed from
above.
Note that for a wing with no taper, the above calculation results in the
same aspect ratio value that will occur by simply dividing the wingspan
by the wing chord.
Regards,
Bob Wilson.
Hi Thomas,
Thanks for the question. The simplest answer is to make several measurements. Each measurement should be evenly spaced along the wing. Then calculate the aspect ratio for each measurement. Then average the results. This procedure will provide an estimate. The exact procedure requires integral calculuswhich you will learn in high school math or college math.
I hope this helps. Please let me know if you have more questions.
Thanks
Jeff Grell
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Update: November 2011

