Vertipedia - Piasecki YH-21 Work-Horse

The development model for the H-21 series. It is distinguishable from the later models by the forks holding the main wheels.

Overview

Data on design, manufacture and status

Design authority: Piasecki Helicopter Corporation

Primary manufacturer: Piasecki Helicopter Corporation

Parent type: Piasecki H-21

Aircraft status: No longer flying

Configuration

Primary flight and mechanical characteristics

VTOL type: Helicopter

Lift devices: 2 in Tandem (Fore/aft) configuration

Crew required: 2 in Side-by-side arrangement

Landing gear: Wheels (non-retractable)

Key Characteristics

Data on key physical features

Aircraft Details

Data on aircraft configuration, weights, flight performance and equipment

Layout and Dimensions

Weights and Performance

Engine Details

Primary Lift Device

Overall Dimensions
Overall Height:	4.86 m	15.9 ft
Overall Length:	26.31 m	86.3 ft
Overall Width:	13.41 m	44.0 ft

Airframe Dimensions
Airframe Length:	16.02 m	52.6 ft
Airframe Width:	3.97 m	13.0 ft
Airframe Height:

Landing Gear Dimensions
Landing Gear Base:	7.51 m	24.6 ft
Landing Gear Track:	4.48 m	14.7 ft

Cabin Dimensions
Cabin Internal Height:
Cabin Internal Length:
Cabin Internal Width:

Cruise Speed: 180 mph (160.934 km/h)

Weights
Max Gross Weight (ground):	5,000 kg	11,022 lb
Max Gross Weight (airborne):
Max Take-off Weight:
Empty Weight:

Climb Performance
Max Rate of Climb:	8 m/s	1,600 fpm

Hover Performance
Hover Ceiling IGE:
Hover Ceiling OGE:

Limitations
Max Level Flight Speed:
Never Exceed Speed:
Service Ceiling:	5,182 m	17,000 ft

Range and Endurance
Max Range:	805 km	434 nm
Max Endurance:

Provided powerplant data is for uninstalled, sea level, static operations.

Powerplant
Number of engines:	1
Designation:	Wright R-1820-103 reciprocating
Manufacturer:	Wright Aeronautical Division, Curtiss-Wright Corporation

Normal Ratings
Max continuous:	951 kW	1275 hp
Take-off / rated:	1063 kW	1425 hp
Intermediate:
Maximum:

OEI Ratings
OEI contingency:
OEI continuous:
OEI 30-second:
OEI intermediate:

Fwd rotor rotates ant-clockwise, aft rotor rotates clockwise

Main Rotor Characteristics
Diameter:	13.41 m	44.00 ft
RPM:	255.0 rpm	255.0 rpm
Direction of Rotation:	Not applicable
Hub Type:	Fully articulated

Main Rotor Blade Characteristics
Blade Construction:	Wooden blades with steel spar and plywood covering
Blade Chord:	0.457 m	1.50 ft
Blade Tip Geometry:	Conventional
Blade Twist:	-0.122 rad	-7.000 deg
Number of Blades:	3

Main Rotor Derived Characteristics
Disc Area:	141.26 m²	1520.6 ft²
Disc Loading:	17.70 kg/m²	3.624 lb/ft²
Solidity:	0.0651

Main Rotor Blade Derived Characteristics
Blade area per blade:	3.07 m²	33.0 ft²
Tip Speed:	179.06 m/s	587.5 fps

Tail Rotor Characteristics
Diameter:
Configuration:	Unknown
Direction of Rotation:	Unknown
RPM:

Tail Rotor Blade Characteristics
Number of Blades:
Blade Construction:	N/A
Blade Chord:
Blade Twist:

Tail Rotor Derived Characteristics
Disc Area:
Solidity:

Tail Rotor Blade Derived Characteristics
Tip Speed:
Blade Area (per blade):

References

References and sources used

Maintenance Instructions Handbook for YH-21, H-21A, H-21B and H-21C

No stated author
T.O. No. 1H-21(Y)-2, 15 Jun 1954 (page 2)
Report or Technical Manual
Revision date 15 Aug 1955

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Overview

Attribution

Number of engines:	1 Reciprocating
Max Level Flight Speed:
Max Range:	805 km	434 nm
Max Endurance:

Main Rotor Diameter:	13.41 m	44.00 ft
Max Gross Weight (ground):	5,000 kg	11,022 lb