Stanisław Sobkow: WS-4 Bis Świerszcz
Stanislaw Sobkow: WS-4 Bis Swierszcz

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Names and dates
Market original model designation
WS-4 Bis
Market model designation (english translation or spelling)
WS-4 Bis
Original model name
Świerszcz
Model name (english translation or spelling)
Swierszcz
Project start date
1959
Date of prototype completion
1967
Tests start date
1968
Country of manufacture
Poland
People involved
Stanislaw Sobkow {Stanisław Sobkow}Constructor
Mateusz GawdzikNo translation available for: func_owner
Config info
Rotorcraft typeHelicopter
Config
Coaxial rotors
Weights
Maximum Takeoff Weight (MTOW)
500
kg
Manufacturers empty weight (MEW)
314
kg
Cabin and cockpit
Maximum number of people onboard
2
Cabin width
1.10
m
Cockpit seating arrangement
Side-by-side
External dimensions
Fuselage length
4.30
m
Fuselage width
1.10
m
Overal height
2.74
m
(...)
3
m
Main rotor
Cyclic control
Swash-plate (direct)
Collective control
Yes
Main rotor diameter
8
m
Number of blades
2
Main rotor blade airfoil
NACA 23012
Main rotor blade twist
-6
°
Powerplant
Engine model
Praga D
Engine type
Piston
Engine dry weight
65
kg
Number of engines
1
Total maximum power
75
HP
(...)
101
HP
Angular speed at max power
2640
rpm
Fuel system
Fuel tank capacity
40
l
Average fuel consumption [volumetric]
12
l/h
Performance
Maximum horizontal flight speed (Vh)
120
km/h
Cruise speed (Vc)
90
km/h
Best rate of climb
2.10
m/s
Maximum service ceiling
2300
m
Hover ceiling OGE
1800
m
Maximum range
350
km
0.0616