Sinus 912

The Pipistrel Sinus 912 is the two-seat motor glider with which Pipistrel moved into composite construction in the mid-1990s. According to Wikipedia the Sinus family first flew on 16 October 1996 and has been in production since 1995; the flight manual refers to Slovenian type certificate no. AT/ULN 01 dated 9 July 1999. The Rotax 912 UL series holds German DULV type data sheet no. 573/04-05 1 (type "Sinus", series "Rotax 912 UL", issued 14 April 2005, last amended 11 November 2015) under the LTF-UL of 30 January 2003, with FLIGHT TEAM UG (haftungsbeschränkt) & Co. KG in Ippesheim as type custodian.

The data sheet describes the airframe as a composite (FVK) shoulder-wing design with T-tail, tailwheel gear and a tractor engine; an NW nosewheel version also exists. A 14.97 m span over 12.26 m² gives an aspect ratio of 18.3, flap settings are -5°, 0°, +9° and +18°, and the CG range is 20–39 % MAC. Its defining feature is the Pipistrel Vario: an adjustable two-blade propeller of 1.62 m diameter that can be feathered, which is what makes the ultralight glide like a motor glider. The same airframe was offered with the Rotax 503 and 582, as the Sinus Flex with interchangeable short wingtips, and as an LSA version for which the manufacturer quotes 585 kg take-off weight, 295 kg empty weight and 290 kg useful load.

With the Rotax 912 UL (59.6 kW / 80 hp at 5,500 rpm) the product page quotes a 200 km/h cruise at 75 % power, while the flight manual states 180 km/h in cruise with the fixed BAM 2 propeller. The data sheet limits VH to 200 km/h, VNE to 225 km/h, VD to 250 km/h and VA to 141 km/h, with VS0 at 65 km/h; at MTOW it stalls at 63 km/h in the second flap setting and 66 km/h with flaps neutral. Best climb is 6.3 m/s at 115 km/h per the data sheet (6.5 m/s per the flight manual), ground roll 93 m, take-off distance over 15 m 153 m, and service ceiling 8,800 m. Gliding with the Vario propeller it achieves 1:29 per the flight manual, or 1:27 at 95 km/h per the product page, and 1:18 at 150 km/h; minimum sink is 1.03 m/s at 90 km/h and the airbrakes allow up to 5.8 m/s. Fuel burn of 9.2 l/h yields 5.8 hours endurance and roughly 1,100 km of range (product page: 1,200 km).

Its strengths are the dual role as tourer and sailplane, low fuel burn, a very short take-off run and a 59.1 dBA noise rating under German LVL rules – valuable at noise-sensitive airfields. The weaknesses: a 14.97 m span needs hangar space or removable wings, and the German data sheet allows only 175 kg of useful load against 297.5 kg empty weight, so with the flight manual's 180 kg maximum crew weight, two heavy pilots and full tanks do not fit. Published empty weights vary by source (297.5 kg on the data sheet, 284 kg in the flight manual for the base model, 285 kg on the product page), so only the aircraft's weighing report settles it. The tailwheel demands practice, and no 600 kg upgrade is documented for the Sinus: the German data sheet lists 450 kg, or 472.5 kg with the GRS 472 recovery system, the product page adds 544 kg, and the manufacturer quotes 585 kg for the LSA configuration. Load limits are +4 g / -2 g.

The Sinus 912 is for pilots who want both – distance at around 200 km/h in the morning and thermalling with the engine shut down in the afternoon. Those who only want to travel will find more speed in the Virus SW; those who only want to soar will find more glide in the Taurus.