SZD Magazine: 20 meter SZD-54-2 Perkoz tests flights completed

Polski

September 29th was the last day of certification test flights of 20 m Perkoz, equipped with long wing extensions. The purpose of the tests was to confirm the compliance with requirements of CS-22 regulations for this modified version of SZD-54-2. 21 take-offs and nearly 15 FH have been flown. The tests went smoothly and confirmed all the calculation assumptions made by SZD designers and aerodynamicist.

The glider will get into service in the same manner as the 17.5 m version. The basic flight parameters are as follows:

VNE - never exceed speed: 240 km/h;
VRA - rough air speed: 160 km/h;
VA - manoeuvring speed: 160 km/h;
VT - max. aerotow speed: 150 km/h;
VW – max. winch launching speed: 110 km/h;
manoeuvring load factors: +5,3 / -2.65 g;
approval for basic aerobatic manoeuvres including half of flick roll & half loop;
cloud flying.

The test flights have covered the following elements:

flight on tow as well as winch launching,
longitudinal, lateral and directional manoeuvreability,
longitudinal, lateral, directional and dynamic stability,
stalls and spins in many different configurations of CG location as well as glider loading,
high speed diving & flutter tests,
airbrakes tests,
basic aerobatic.

Our test pilot stated the glider has passed the exams perfectly. In addition to the already emphasized advantages (including canopy ergonomy, light and effective controls, manoeuverability and stability), flutter tests were finished safely (damping arises immediately, the glider is free of flutter, aerofoil divergence and control are reversal in each configuration). Also the results of tests with extended airbrakes while flying with max. permitted speed were positive. The efficient airbrakes allow to fly the glider with VNE in a dive at an angle of 50° to the horizon (the regulations say min. 45°). This is a very good result.

The spin seems to be abrupt with a relatively significant altitude lost, however it is possible to stop spinning immediately. Recovery is safe and easy. The glider does not have the tendency to uncontrollable spin, stalling behaviour is not unduly sensitive to sideslip, there is also no tendency to sideslip while turning or changing the spin into a spiral dive. 20 m Perkoz is highly manoeuverable and easy to control, even while flying with a minium speed.

The 20 m version is one of a few configurations of SZD-54-2 Perkoz. In opposite to relatively heavy and less monouverable foreign designs, our doubleseater may be used by the pilots on each level of their gliding experience. Perkoz will meet the expectations of the most demanding and ambitious aviators.