Ben Owen

WING INCIDENCE 'urtis Pitts designed this neat little incidence tool, very simple to make and very easy to use. You can use any level, but with a round adjustable one, you don't have to jack the tail up to determine the incidence. Most people, including myself, who have built a wing incidence tool try to build one to the contour of the upper wing. This is unnecessary. If you have a Pitts or an Acro Sport I, this wing incidence tool will work for

dence tool.

Don't

build one that

matches the wing upper contour. It is unnecessary, and it won't be any more

accurate than the simple one. Now that you've got one built, what do you do with it? Well, you can use it in initial rigging, and also for in-field rigging after you have flown the airplane

and made some adjustments. If you

you. If you have another type of aircraft,

have a biplane or a strut braced aircraft, you can probably still adjust the wing incidence after it is built. Otherwise, you

you should use the rib drawing to determine how to build this simple wing inci-

are going to have to use the tool carefully during construction. A monocoque

wing covered with wood, metal and fiberglass obviously is going to be too rigid to adjust when it is done. However,

before you put those skins on, a tool such as this will certainly help you get that incidence correct. For those of you with biplanes or

other aircraft that can be adjusted in the field for incidence, I would like to tell you about Johnny Livingston's tool. Johnny was an old time race pilot with

nearly as many race wins as Steve Wittman, and he lived in south Florida. He would come out to the airport with

four suction cups attached to a 1/2" dowel rod. The dowel rods were about 2" to 3" high. For a thicker wing airplane, like an EAA Biplane, about 3" to 4" is about right. If you buy suction cups with screws or bolts molded into them, you

WING INCIDENCE TOOL i" X 3/4"

3"

x ^ A—————————————————————————

T ^ , ADJUSTABLE LEVEL

__ t_

t

s

T

T 51/4"

18%" *

. .... ————— .. ———————

O41A"

—————————————

can easily adjust all four to the same height. If you line up the trailing edge by sighting across the top of the wing, you usually have a fairly straight wing.

The more you do this, the better you get at it. Note: Books available from EAA in-

clude the CAM 18, predecessor to the With this tool, the incidence along the wing (or wash-in and wash-out along the wing) can be checked to eliminate any twist. The dimensions shown are for either Pins or Acro Sport I. The tool is useful for any aircraft, but dimensions may need

AC 43.13. The CAM 18 is reprinted in

to be changed. The better the level used - the more accurate the tool. - ED -

version. If you can read the small print, we have a manual titled "Aircraft Repair Manual" that contains the AC 43.13-1 and the AC 43.13-2. The 43.13-1 (a) was printed in 1972 and the 14.13-2(a) in 1977. All of these contain essentially the same information. The CAM 18 is available for $4.50. The "Aircraft Repair Manual" is available at $10.95. Add $2 for the first book and $1 for subsequent

big type, has had quite a few pictures added to it and is the "easy reading"

books to cover postage and handling. Order from EAA Aviation Foundation, Dept. M.O., Wittman Field, Oshkosh, Wl 549030-3065. Most major credit cards are accepted. Please include your credit card number, expiration date, name, address and daytime phone number. Wisconsin residents

please add 5% sales tax. Allow 4-6 weeks for delivery.

60 JANUARY 1987