To the Pole and Back
Interesting article in Wings Magazine this month on the flight to the South Pole by Kenn Borek Air in April of this year.
The two Twotters were equipped with -34 engines of 750 shp instead of the standard -27 engines of 650 hp. This gave them an increased overload MTOW of 17,500 lb. for this specific flight. For nav purposes, they had a Litton LTN 92 Laser Gyro INS and an IFR GPS.
They ferried the aircraft to Rothera on wheels, and fitted the wheel/skis there. Loutitt wanted to use straight boards, but he didn't want to be forced to use the ski strip at Rothera, because of the higher elevation.
They left Rothera at 14.32 GMT on April 24, and cruised at 10,000 ft to avoid headwinds at higher altitudes. They climbed to 10,300 before arrival, since the elevation of the skiway at the pole is 9,300 ft. Their average G/S for the trip was 145 kt. Weather on arrival at the pole was 26,000 feet in ice crystals, wind five kt and the surface temp -68C. Total flight time was 9.3 hours.
The aircraft was equipped with electrical heaters which were plugged in immediately after the engine covers were installed. The electrical cords were covered in heat tape to ensure they didn't crack. As well, the INS and the aircraft batteries were removed while the aircraft was on the ground.
The aircraft pre-start took four hours, using Herman Nelsons for the engines and cabin. After all that, oil temps were +30 when they reinsatlled the batteries. The base had a thousand gallons of JP8 stored in a building at +10, which was down to about -5 when it was boarded. Their requirements were that the fuel be no colder than -20. There was one snag prior to departure. The elevator trim was frozen, and took an hour to thaw.
On departure, the aircraft didn't want to budge, even at max power. Loutitt used a combination of forward and reverse power, and with the ground crew rocking the wings finally got the aircraft to move. He says that at 17,000 lb, the aircraft had settled and stuck in the soft snow. They backtracked a short way, and took off. They had been on the ground a total of 16 hours.
With favourable winds, the flight back to Rothera took 8.3 hours. They had to do an ADF approach to minimums, and Loutitt said he was happy he hadn't used the straight skis. The limits on the skiway were below minimums.
In an interesting note, the second aircraft was to have been used as a crew rescue aircraft only. If the first aircraft had gone down, the second was to evacuate the crew only. The downed aircraft would have sat on the icecap until next summer.