Engineering topics

Dunham, Dana Morris

Publications and source records attributed to Dunham, Dana Morris.

3 records

NASA NTRS1991

Effect of solidity and inclination on propeller-nacelle force coefficients

A series of wind tunnel experiments were conducted to study the effect of propeller solidity and thrust axis inclination on the propeller normal force coefficient. Experiments were conducted in the Langley 14 by 22 foot Subsonic Tunnel with a sting mounted, counterrotation, scale model propeller and nacelle. Configurations had two rows of blades with combinations of 4 and 8 blades per hub. The solidity was varied by changing the number of blades on both rows. Tests were conducted for blade pitch setting of 31.34 deg, 36.34 deg, and 41.34 deg over a range of angle of attack from -10 deg to 90 deg and range of advance ratio from 0.8 to 1.4. The increase in propeller normal force with angle of attack is greater for propellers with higher solidity.

Gentry, Garl L., Jr.↗

NASA NTRS1989

The effect of solidity on propeller normal force

Propeller normal force is a major contributor to pitch and yaw stability on propeller driven aircraft. While it is well known that propeller normal force is a function of the number of blades, there are no published data for the high numbers of blades that are used in the new designs such as the UDF. This paper presents the results of a test conducted in the NASA Langley 14- x 22-foot Subsonic Tunnel using a sting-mounted counter-rotation propeller and nacelle. The configurations tested were combinations of 0, 4, and 8 blades per hub. Tests were conducted for blade angle settings of 31.34, 36.34, and 41.34 deg over an angle-of-attack range from -10 to 90 deg and over a range of advance ratios from 0.8 to 1.4. The results show that propeller normal force varies with both solidity and angle of attack.

Dunham, Dana Morris↗

NASA NTRS1987

Low-speed aerodynamic characteristics of a twin-engine general aviation configuration with aft-fuselage-mounted pusher propellers

An investigation was conducted to determine the aerodynamic characteristics of an advanced turboprop aircraft model with aft-pylon-mounted pusher propellers. Tests were conducted through an angle-of-attack range of -8 to 28 degrees, and an angle-of-sideslip range of -20 to 20 degrees at free-stream conditions corresponding to Reynolds numbers of 0.55 to 2.14 x 10 to the 6th power based on mean aerodynamic chord. Test results show that for the unpowered configurations the maximum lift coefficients for the cruise, takeoff, and landing configurations are 1.45, 1.90, and 2.10, respectively. Nacelle installation results in a drag coefficient increase of 0.01. Increasing propeller thrust results in a significant increase in lift for angles of attack above stall and improves the longitudinal stability. The cruise configuration remains longitudinally stable to an angle of attack 5 degrees beyond the stall angle, the takeoff configuration is stable 4 degrees beyond stall angle, and the landing configuration is stable 3 degrees beyond stall angle. The predominant effect of symmetric thrust on the lateral-directional aerodynamic characteristics is in the post-stall region, where additional rudder control is available with power on.

Dunham, Dana Morris↗