7 - 4 Page Date: 20. April 2002
Section 7
Description and Operation of Aircraft and Systems
PilotĀ“s Operating Handbook
EXTRA 300S
7.3 WINGS
The wing is of CRP construction. The dual chamber main spar - being a fail safe design -
consists of carbon roving caps combined with CRP webs. Core foam is a PVC foam
(Divinycell HT 50). The wing shell is built by a Honeycomb sandwich with CRP laminates.
To improve surface quality and for protection of the carbon wing shell an outer layer of glass
fibre, except of the tank area, is applied. In the area of the wing tanks is a layer of CRP
laminate with an incorporated aluminium thread bonded to the metal fuselage structure as
means of lightning protection. To prevent buckling of the shell plywood ribs are installed.
These ribs are permanently protected from environmental effects by an epoxy coating.
The connection to the fuselage is arranged by two bolts piercing through the spar parallel to
the centerline of the fuselage and two brackets at the rear spars.
Integral fuel cells are provided in the leading edge of the wing extending from the root ribs to
half the span of each R/L and L/H wing.
The ailerons are supported at three points in spherical bearings pressed into aluminium
brackets.
To reduce pilot's hand forces the hinge line of the ailerons is positioned 25% of the aileron
depth at the root and 21,5% at the tip. Furthermore the ailerons are equipped with "spades"
to decrease pilot forces. Ailerons are controlled via the center bracket.
To prevent flutter the ailerons are weight balanced in the overhanging leading edge.
7.4 EMPENNAGE
The EXTRA 300/S possesses a cruziform empennage with stabilizers and moveable control
surfaces. The rudder is balanced aerodynamically at the tip. Spars consist of PVC foam
cores, CRP caps and GRP laminates. The shell is built by honeycomb sandwich with GRP
laminates. Buckling is prevented by plywood ribs.
Deviating from the other control surfaces the elevator, due to aerolastic reasons, entirely is
built by CRP. On the R/H elevator half a trim tab is fitted with two hinges. The control
surfaces are mounted in spherical bearings (exception: Trim tab). To prevent flutter rudder
and elevator are mass balanced. The balance weight for the rudder is installed in the rudder
tip while the balance weight for the elevator is mounted on the elongated center bracket of
the elevator extending into the fuselage.
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