P&M Aviation QUIK GT450 Operating Instructions Manual page 41

Tuning turns
Example: The aircraft turns right at all speeds. The trim speed is correct.
Solution: In this case the tip turn adjusters. On the tips you will find an adjustment scale where
the leading edge emerges from the sail. Rotate the starboard tip plug 1mm on the scale anti-
clockwise (i.e. trailing edge down). Check in flight. If the turn persists, rotate the tip one further
mm. Check fly. Rotate the left tip 1mm anti-clockwise (i.e. trailing edge up). Check results
before moving the tips further.
Example: At high speed, the aircraft turns to the right. At low speed, the turn is not so
pronounced. The trim speed is correct.
Solution: Use ribs numbers 7-10 (the tip rib is number 11 and has very little effect) on the
starboard (right wing) side to tune out the turn. The tip ribs respond well to "tab effect", i.e.
application of reflex near to the trailing edge will produce a downforce at the trailing edge which
will increase the incidence of the section as a whole. The overall effect is to increase the lift on
the side where reflex is applied, so correcting the turn. The effect becomes more pronounced as
the speed rises. The reflex should be applied 200mm (8 inches) from the trailing edge and
applied in small increments up to a maximum of 25mm (1 inch). Start with 10mm (3/8 inch)
reflex, test fly, then 15 - 20 - 25mm (5/8 - 3/4 - 1 inch) as required. Do not exceed 25mm reflex!
Example: The wing flies completely straight sometimes, and turns to the right at other times!
Solution: This is happily an easy problem to solve, since it usually only happens when you
have to rig everytime you fly. Then it is a question of exactly how the tension sets up on the
outer leading edge webbings. Simply take hold of the leading edge cloth right out near the
trailing edge and twist it anti-clockwise; you should feel it move. It will then be held there by the
tension.
Tuning in pitch
The GT450 wing is designed to be stable in pitch even with the trimmer fully fast, at a trim speed of 73 - 80
mph. The bar force when pulling in must steadily rise to at least 7kg (15 lbs) to achieve 95mph.
The electric trimmer applies a spring nose-up moment to the wing directly. In the fast trim setting, the trim
cord should be just slack with the bar fully in to the pilot's chest.
When making adjustments in pitch, always tune in smooth air and climb to test altitude with the trimmer set at
60 mph, before winding the trimmer gradually to the test position. The settling of the sail on the airframe
generally tends to slow the wing down and make it more stable both in pitch and laterally/directionally, as the
washout increases.
If the wing has slowed unacceptably with the trimmer fully fast, then the tip adjusters can be rotated both
together by 1mm on the scale so as to bias the trailing edges downwards. Check the result at each 1mm
adjustment until the trim speed and pitch feel are correct. Do not exceed 5mm of adjustment.
As a rough guide, the sail should ride approximately 25mm (1 inch) clear of the washout rods when flying
solo at fast trim.
If the trim speed is too fast and pitch feel too light at the fast trim setting, then the tips can be rotated both
upwards until the correct speed is set. Again, use small adjustments to achieve the desired result. If the wing
is very new (less than 5hrs) then it will probably settle down by 4-5mph over the next 20hrs.
Once the fast trim has been set, then the slow trim can be checked by winding to the full slow position. The
slow trim will be 5 mph faster at maximum all-up weight than at minimum loading.
Quik & Quik GT450 Aircraft Operating Instructions
th
29 March 2007
Issue 1
WARNING
!
Do not exceed the adjustment range which is
±6mm (1/4 inch) from the initial factory setting,
or the aircraft may become unstable.
Page 41 of 68