Vertipedia - Seibel S4A (YH-24 Skyhawk)

Developed in 1948, under the U.S. Army the Seibel S4A was designated the YH-24 Skyhawk.

Overview

Data on design, manufacture and status

Design authority: Seibel Helicopter Company

Primary manufacturer: Seibel Helicopter Company

Parent type: No type defined

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: 1-2 in Tandem 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

Primary Control Device

Overall Dimensions
Overall Height:
Overall Length:
Overall Width:	8.84 m	29.0 ft

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:

Cruise Speed: 65 mph (104.607 km/h)

Weights
Max Gross Weight (ground):	680 kg	1,500 lb
Max Gross Weight (airborne):
Max Take-off Weight:	680 kg	1,500 lb
Empty Weight:	435 kg	960 lb
Useful Load:	245 kg	540 lb
Empty Weight Fraction:	0.640

Climb Performance
Max Rate of Climb:	4 m/s	700 fpm

Hover Performance
Hover Ceiling IGE:
Hover Ceiling OGE:

Limitations
Max Level Flight Speed:
Never Exceed Speed:
Service Ceiling:	3,170 m	10,400 ft

Range and Endurance
Max Range:	185 km	100 nm
Max Endurance:

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

Powerplant
Number of engines:	1
Designation:	Lycoming O-290-D reciprocating
Manufacturer:	Lycoming Engines

Normal Ratings
Max continuous:
Take-off / rated:	93 kW	125 hp
Intermediate:
Maximum:

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

Main Rotor Characteristics
Diameter:	8.84 m	29.00 ft
RPM:
Direction of Rotation:	Unknown
Hub Type:

Main Rotor Blade Characteristics
Blade Construction:
Blade Chord:
Blade Tip Geometry:
Blade Twist:
Number of Blades:	2

Main Rotor Derived Characteristics
Disc Area:	61.36 m²	660.5 ft²
Disc Loading:	11.09 kg/m²	2.271 lb/ft²
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:	2
Blade Construction:
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

Helicopters & Autogyros of the World

Paul Lambermont, Anthony Pirie
Cassell & Company Ltd., 1959 (page 372)
Book

S-47 | S-47/R-4 Helicopter

Vinny Devine
Sikorsky Archives | Product History, Sep 19, 2017 (page 13)
Website
Very thorugh description and details of the R-4 series helicopter

Related VFS Resources

Resources related to the S4A (YH-24 Skyhawk), provided by the Vertical Flight Society.

Forum Proceedings

Vertiflite articles

Enter a search term in the box above.

Web files from vtol.org

Enter a search term in the box above.

Webpages from vtol.org

Enter a search term in the box above.

Images from the VFS Gallery

Enter a search term in the box above.

Refine / filter your search or find more resources

Related Public Resources

Resources related to the S4A (YH-24 Skyhawk), provided by public sources across the internet.

Publicly-funded resources provided by the US Government

NASA Technical Reports Server (NTRS)

Enter a search term in the box above.

Defense Technical Information Center (DTIC)

Enter a search term in the box above.

SciTech Connect (OSTI)

Enter a search term in the box above.

Public resources provided by select scholarly and academic sources

European Rotocraft Forum Document Repository (ERF)

Enter a search term in the box above.

IOPscience (IOP)

Enter a search term in the box above.

CiteSeerX (CiteSeerX)

Enter a search term in the box above.

Google Books (Google)

Enter a search term in the box above.

Additional links

Search for at Google Scholar.

Search for at ScienceResearch.com.

Search for at Semantic Scholar.

Search for at Microsoft Academic.

Number of engines:	1 Reciprocating
Max Level Flight Speed:
Max Range:	185 km	100 nm
Max Endurance:

Main Rotor Diameter:	8.84 m	29.00 ft
Max Gross Weight (ground):	680 kg	1,500 lb
Useful Load (calculated):	245 kg	540 lb