1093

OTHER: Helicopter - Outside - Intermeshing - Stepniewski (concept)

CICHE WIROPŁATY (Quiet Rotorcraft)

Implications of the Low Tip Speed Design Philosophy

NACA Report Published: Jan 01,1997 ~ Book Published: 1999

Abstract; Common to the NACA Report (23 pages) and the Book (119 pages):

In this report implications of the low tip speed design philosophy are studied with respect to
rotorcraft capable of fast cruise speed, roughly 50% higher than that of conventional helicopters.
This is done by examining effects of tip speeds on some performance and structural-weight
aspects of compounds, based on the following concepts:

Cold-jet-driven rotor in hover and transition flight, autorotating in cruise; ~ He used the Djinn and the Rotodyne Voljet.

Single rotor configuration with shaft-driven rotor in all regimes of flight; ~ He used the Piasecki's vectored flow ducted propeller

Synchropter, incorporating the ABC principle. ~ He used the Sikorsky ~ XH-59A ABC as the basis for his work on a Synchropter-ABC.

His preference is; #3, the Intermeshing-ABC (Synchropter-ABC).

His Comments:

"Very preliminary studies seem to indicate that placing the ABC rotors in the Synchropter position should result in a somewhat aerodynamically cleaner than the coaxial ABC, and definitely a much cleaner design than the considered single-rotor types."

"The ABC Synchropter configuration appears to have the highest potential for low SHP_cr values up to the cruise speed as high as V_cr ≈ 260 knots, when the advancing tip Mach number is no higher than M_AT = 0.85."

"It appears that the ABC Synchropter concept should be further investigated as a potential candidate for the quiet rotorcraft."

Sketch of the Synchropter-ABC ~ from the above two publications:

The NASA Technical Report:

TITLE: Quiet Rotorcraft
Document ID: 19970040549 N (97N31691) File Series: NASA Technical Reports
Report Number: None
Sales Agency & Price: CASI Hardcopy A03 o CASI Microfiche A03 - No Copyright
Authors:
Stepniewski, Wieslaw Z. (Instytut Lotnictwa)
Journal Title: Transactions of the Institute of Aviation Scientific Quarterly o Issue: Nos. 149-150
Page: 43-65

Published: Jan 01,1997
Corporate Source:
Instytut Lotnictwa (Warsaw, Poland)
Pages: 23
Contract Number: None
NASA Subject Category: Aircraft Design, Testing and Performance

Language: Polish

The Book:

CICHE WIROPŁATY
Wyd. II, 1999 119 pp. Price $ 20, No ISBN 83-904367-5-2

119 pages written by Prof. Wiesław Zenon Stępniewski, which is the full version of the above report.

Language: Polish.

Notes:

Direction of rotation: Is outside forward. This differs from all other intermeshing helicopters, except for the UniCopter w/ ABC.

Tip speed: (V_t) 513 fps - fixed.

Some of Wiesław Zenon Stępniewski's 89+ Publications:

Rotary-Wing Aerodynamics 600 page book, available at Amazon for $19.67

Open Airscrew VTOL Concepts ~ 232 page report, freely available on the Internet from NASA.

A comparative study of Soviet versus Western helicopters. Part 1: General comparison of designs ~ 298 page report, freely available on the Internet from NASA.

More Stepniewski reports freely available from NASA

Related Pages:

OTHER: Rotor Concept - Active Blade Twist

OTHER: Rotor Concept - Independent Root & Tip Control

OTHER: Rotor Concept - Reverse Velocity Utilization

OTHER: Rotor Concept - Yaw Control for Twin Rotor Configurations

OTHER: Flight Dynamics - Control - Variable Vertical Fin

Last Revised: July 22, 2008