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Wind Tunnel Investigation of a Plain Aileron and a Balanced Aileron on a Tapered Wing with Full Span Duplex Flaps

'SUIIIARY

An investigation was made of a plain aileron and a balanced
aileron on a tapered wing with full-span duplex flaps , which con-
sisted of an inboard NACA slotted flap and an outboard balanced.
split flap. 'Ihe investigation was made in the 7- by 10-foot wind
tunnel of the Langley Mmerial Aeronautical Laboratory. Increments
of maximum lift coefficient of 0.82 and 1.01!- were obtained from the
inboard flap alone and from the duplex-flap combination, respectively.
The aileron was as effective with flaps fully extended as with flaps
retracted, but a 30-percent reduction of aileron effectiveness appears
unavoidable at intermediate positions of the outboard flap. If this
reduction is acceptable, the wing arrangement tested should be
satisfactory. Estimated rates of roll and stick forces for the
arrangement on a fighter airplane are given.

IN'JEONCTION

Increased speed and wing loading of modern airplanes have led to
difficulties in obtaining high lifts for landing and take-off without
impairing lateral control. In order to obtain solutions for this
problem, the NACA is investigating, on a senispan model of the tapered

' wing of a modern fimter airplane, lateral-control devices that

appeared praising from'wind-tunnel tests on a rcctengllar wing with
a square tip. .

The present tests were made of a plain and a balanced aileron
on a wing with full-span "duplex" flaps consisting of an inboard HACA
slotted flap and an outboard balanced split flap. Iibis work may be

‘coné'idort-d‘an eifiens'ion of the work? reported in reference 1. A

similar arrangement is to be flight-tested. 'Ihe chect of the wind-
tunnel tests was to determine the lift characteristics and the
aileron-control characteristics for various locations of the outboard
2

flap and for various amounts of aileron balance.

his stick forces and the rates of roll were estimated for an
airplane with the outboard-flap in several positions along a parti-
cular flap path. ' '

APPARAIUS ANDME'IEOIB

A saniepan model was suspended in the 7- by 10-foot wind
tunnel (reference 2 of the Langley Memorial Aeronautical Laboratory
as shown schematically in figure 1. The root chord of- the model was
adJacent to one of the vertical walls of the tunnel, the vertical wall
thereby serving as a reflection plane. The flow over a sanispen in
this set-up is essentially the same as it would be over a complete
wing in a 7- by 20-foot wind tunnel. Although a very small clearance
was maintained. between the root chord of the model and the tunnel well,
no part of the model was fastened to or in contact with the tunnel
wall. The model was suspended entirely from the balance frame, as
shown in figure 1, so that all the forces and moments acting on the
model might be determined. Provisions were made for changing the angle
. of attack while the tunnel was in operation. ' .

The ailerons were deflected by means of a calibrated torque rod
connecting the outboard. and: of the aileron. with a crank outside the
tunnel wall the hinge moments being determined from the twist of the
rod fig. 1 . -