Vertipedia - Lockheed XH-51A (3 blade configuration)

This is the original aircraft in a 3 main blade configuration. Also known by the company designation CL-595.

The aircraft was designed for a very low drag configuration. Apart from the retractable skids, the aircraft had flush rivetted skins and the rotor shaft was tilted 6 deg fwd to keep the fuselage at a low angle of incidence in high speed forward flight.

Overview

Data on design, manufacture and status

Design authority: Lockheed-California Company

Primary manufacturer: Lockheed-California Company

Parent type: Lockheed CL-595

Aircraft status: No longer flying

Configuration

Primary flight and mechanical characteristics

VTOL type: Helicopter

Lift devices: 1 Single main rotor

Dedicated control device: 1 Tail rotor

Crew required: 1 in Side-by-side arrangement

Landing gear: Skids (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

Primary Control Device

Overall Dimensions
Overall Height:
Overall Length:
Overall Width:

Airframe Dimensions
Airframe Length:
Airframe Width:
Airframe Height:

Landing Gear Dimensions
Landing Gear Base:
Landing Gear Track:

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

Weights
Max Gross Weight (ground):
Max Gross Weight (airborne):
Max Take-off Weight:
Empty Weight:

Climb Performance
Max Rate of Climb:

Hover Performance
Hover Ceiling IGE:
Hover Ceiling OGE:

Limitations
Max Level Flight Speed:	280 km/h	151 kts
Never Exceed Speed:
Service Ceiling:

Range and Endurance
Max Range:
Max Endurance:

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

Powerplant
Number of engines:	1
Designation:	P&WC PT6B-9 turbine
Manufacturer:	Pratt & Whitney Canada

Normal Ratings
Max continuous:
Take-off / rated:	410 kW	550 hp
Intermediate:
Maximum:

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

Main Rotor Characteristics
Diameter:	10.67 m	35.00 ft
RPM:
Direction of Rotation:	Unknown
Hub Type:

Main Rotor Blade Characteristics
Blade Construction:
Blade Chord:
Blade Tip Geometry:
Blade Twist:
Number of Blades:	3

Main Rotor Derived Characteristics
Disc Area:	89.38 m²	962.1 ft²
Disc Loading:
Solidity:

Main Rotor Blade Derived Characteristics
Blade area per blade:
Tip Speed:

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

Lockheed

Michael J. Hirschberg
The American Helicopter | An Overview of Helicopter Developments in America 1908-1999, July 2000 (page 69)
Book
Good high level summary of pre-2000 Lockheed VTOL aircraft development