Specifications of Standard Cirrus Sailplanes

Specifications

Not to be confused with its predecessor, the 18 meter (Open) Cirrus, the Standard Cirrus is a completely different ship, a standard class glider (15 meter span without flaps) with airbrakes on the upper wing surface only. It has an all-flying elevator and a steel-tube frame in the fuselage to which the wings and the main-wheel retraction mechanism are attached. The wings are of a PVC foam core construction with a fiberglass skin.

Except as noted, the following figures are from the book Segelflugzeuge: Vom Wolf zum Discus by Peter F. Selinger (Motorbuch Verlag Stuttgart). You should consult your owner's manual and placards for values specific to your aircraft.

	Standard Cirrus	Cirrus 75	Cirrus 75B (with 16m tips)
Number of seats	1	1	1
Airfoil, Wing (1)	Wortmann Root Rib: FX S 02-196 Inner Panel: Linear Transition Aileron Panel: FX 66-17 A II-182 twist angle before #175 (?) (4): 0.75 deg. twist angle from #175 (?) (4): 1.5 deg.	Wortmann Root Rib: FX S 02-196 Inner Panel: Linear Transition Aileron Panel: FX 66-17 A II-182 twist angle: 1.5 deg.	Wortmann Root Rib: FX S 02-196 Inner Panel: Linear Transition Aileron Panel: FX 66-17 A II-182 twist angle: 1.5 deg.
Airfoil, Elevator (2)	NACA 65-012	NACA 65-012	NACA 65-012
Airfoil, Vertical Stabilizer (2)	NACA 63-013A/012A	NACA 63-013A/012A	NACA 63-013A/012A
Wing span	49.2 ft 15 m	49.2 ft 15 m	52.5 ft 16 m
Wing area	107.5 sq ft 10.0 sq m	107.5 sq ft 10.0 sq m	111.4 sq ft 10.36 sq m
Wing loading	5.6-6.8 lb/sq ft 27.2-33.0 kg/sq m	5.9-8.0 lb/sq ft 28.5-39.0 kg/sq m	5.8-6.5 lb/sq ft 28.0-31.85 kg/sq m
Aspect ratio	22.5	22.5	24.7
Empty weight	445 lb 202 kg	473 lb 215 kg	485 lb 220 kg
Payload	282 lb 128 kg	386 lb 175 kg	243 lb 110 kg (3)
Gross weight	728 lb 330 kg	860 lb 390 kg	728 lb 330 kg
Water ballast	132 lb 60 kg	132 lb 60 kg	0 lb 0 kg
Minimum Sink Rate	128 ft/min @ 41 kts 0.65 m/sec @ 75 km/h	124 ft/min @ 42 kts 0.63 m/sec @ 78 km/h	118 ft/min @ 42 kts 0.60 m/sec @ 78 km/h
Maximum L/D	36 @ 51 kts and 5.7 lb/sq ft @ 95 km/h and 28.0 kg/sq m	37 @ 50 kts and 6.3 lb/sq ft @ 93 km/h and 30.6 kg/sq m	38 @ 48 kts and 6.1 lb/sq ft @ 88 km/h and 29.8 kg/sq m

(1) Source: Helmut Treiber, Schempp-Hirth
(2) Source: Fred Thomas, Fundamentals of Sailplane Design
(3) Corrected from Selinger's 180 kg, assuming gross weight is correct at 390 kg
(4) Approximate serial number (If anyone has the exact number please tell Jim Hendrix.
Sources:
- for latter value (1.5 deg) and approximate s/n of change (175): J. Laude, Schempp-Hirth;
- for earlier value (.8 deg): Fred Thomas, Fundamentals of Sailplane Design; however, George Moffat, Winning On The Wind, pg.72, states that .75 degrees were added. I assume that Fred Thomas rounded up since he lists twist angles only in tenths of a degree.

Although the manual for a model-A Standard Cirrus claims a best L/D of 38 at 46 kts, Paul Bikle measured 35.2 for an model-A at 51 kts and Dick Johnson measured 35.9 for a model-B also at 51 kts.

Again, the manual for a model-A claims a minimum sink rate of 112 ft/min at 38 kts; whereas, Paul Bikle measured 134 ft/min at 42.5 kts.