Family of airfoil shapes for rotating blades

An airfoil which has particular application to the blade or blades of rotor aircraft such as helicopters and aircraft propellers is described. The airfoil thickness distribution and camber are shaped to maintain a near zero pitching moment coefficient over a wide range of lift coefficients and provide a zero pitching moment coefficient at section Mach numbers near 0.80 and to increase the drag divergence Mach number resulting in superior aircraft performance

Experimental investigation of three helicopter rotor airfoils designed analytically

Three helicopter rotor airfoils designed analytically were investigated in a wind tunnel at Mach numbers from about 0.30 to 0.90 and Reynolds from about 0.8 to 2.3 x 10 to the 6th power. The airfoils had thickness-to-chord ratios of 0.08, 0.10, and 0.12 with maximum thickness at 40 percent chord. The camber distribution of each section was the same with maximum camber at 35 percent chord. The 10-percent-thick airfoil was also investigated at Reynolds numbers from 4.8 to 9.4 x 10 to the 6th power. The drag divergence Mach number of the 10-percent-thick airfoil is about 0.83 at a normal-force coefficient of 0 and about 0.72 at a normal-force coefficient of 0.6 at Reynolds numbers near 9 x 10 to the 6th power. The maximum normal-force coefficient is slightly less than that of the NACA 0012 airfoil tested in the same facility. The results indicate that a qualitative evaluation of the drag divergence can be made at normal-force coefficients up to the onset of boundary-layer separation by analytically predicting the onset of sonic flow at the airfoil crest. The qualitative results are conservative with respect to experimental values with the experimental drag divergence Mach number up to 0.05 higher than that indicated by analysis

Aerodynamic characteristics of three helicopter rotor airfoil sections at Reynolds number from model scale to full scale at Mach numbers from 0.35 to 0.90

An investigation was conducted in the Langely 6 by 28 inch transonic tunnel to determine the two dimensional aerodynamic characteristics of three helicopter rotor airfoils at Reynolds numbers from typical model scale to full scale at Mach numbers from about 0.35 to 0.90. The model scale Reynolds numbers ranged from about 700,00 to 1,500,000 and the full scale Reynolds numbers ranged from about 3,000,000 to 6,600,000. The airfoils tested were the NACA 0012 (0 deg Tab), the SC 1095 R8, and the SC 1095. Both the SC 1095 and the SC 1095 R8 airfoils had trailing edge tabs. The results of this investigation indicate that Reynolds number effects can be significant on the maximum normal force coefficient and all drag related parameters; namely, drag at zero normal force, maximum normal force drag ratio, and drag divergence Mach number. The increments in these parameters at a given Mach number owing to the model scale to full scale Reynolds number change are different for each of the airfoils

Two-dimensional aerodynamic characteristics of three rotorcraft airfoils at Mach numbers from 0.35 to 0.90

Three airfoils designed for helicopter rotor application were investigated in the Langley 6- by 28-inch Transonic Tunnel to determine the two dimensional aerodynamic characteristics at Mach numbers from 0.34 to 0.88 and respective Reynolds numbers from about 4.4 x 10(6) power to 9.5 x 10(6) power. The airfoils have thickness-to-chord ratios of 0.08, 0.10, and 0.12. Trailing-edge reflex was applied to minimize pitching moment. The maximum normal-force coefficient of the RC(3)-12 airfoil is from 0.1 to 0.2 higher, depending on Mach number M, than that of the NACA 0012 airfoil tested in the same facility. The maximum normal-force coefficient of the RC(3)-10 is about equal to that of the NACA 0012 at Mach numbers to 0.40 and is higher than that of the NACA 0012 at Mach numbers above 0.40. The maximum normal force coefficient of the RC(3)-08 is about 0.19 lower than that of the NACA 0012 at a Mach number of 0.35 and about 0.05 lower at a Mach number of 0.54. The drag divergence Mach number of the RC(3)-08 airfoil at normal-force coefficients below 0.1 was indicated to be greater than the maximum test Mach number of 0.88. At zero lift, the drag-divergence Mach numbers of the RC(3)-12 and the RC(3)-10 are about 0.77 and 0.82, respectively

Low speed aerodynamic characteristics of NACA 6716 and NACA 4416 airfoils with 35 percent-chord single-slotted flaps

An investigation was conducted in a low-turbulence pressure tunnel to determine the two-dimensional lift and pitching-moment characteristics of an NACA 6716 and an NACA 4416 airfoil with 35-percent-chord single-slotted flaps. Both models were tested with flaps deflected from 0 deg to 45 deg, at angles of attack from minus 6 deg to several degrees past stall, at Reynolds numbers from 3.0 million to 13.8 million, and primarily at a Mach number of 0.23. Tests were also made to determine the effect of several slot entry shapes on performance

It\u27s Midnight. Do you know how your patient is doing?

Transitions of care are vulnerable points in patient care. With the volume of information transferred, quality of care and patient safety are at risk. Numerous attempts at standardization of transitions of care have been utilized; however no consensus regarding the optimal method has been reached. We developed a “watcher” model in addition to standard end of shift sign out. Patients at risk were identified by the day team and seen overnight by a senior and junior surgery resident, along with a nursing representative: either a bedside RN or nursing supervisor. We hypothesized that these midnight rounds could proactively identify patient care issues and intervention would be implemented sooner in a patient’s hospital coursehttps://jdc.jefferson.edu/patientsafetyposters/1036/thumbnail.jp

Effect of blade planform variation on the forward-flight performance of small-scale rotors

An investigation was conducted in the Glenn L. Martin Wind Tunnel to determine the effect of blade planform variation on the forward-flight performance of four small-scale rotors. The rotors were 5.417 ft in diameter and differed only in blade planform geometry. The four planforms were: (1) rectangular; (2) 3:1 linear taper starting at 94 percent radius; (3) 3:1 linear taper starting at 75 percent radius; and (4) 3:1 linear taper starting at 50 percent radius. Each planform had a thrust-weighted solidity of 0.098. The investigation included forward-flight simulation at advance ratios from 0.14 to 0.43 for a range of rotor lift and drag coefficients. Among the four rotors, the rectangular rotor required the highest torque for the entire range of rotor drag coefficients attained at advanced ratios greater than 0.14 for rotor lift coefficients C sub L from 0.004 to 0.007. Among the rotors with tapered blades and for C sub L = 0.004 to 0.007, either the 75 percent tapered rotor or the 50 percent tapered rotor required the least amount of torque for the full range of rotor drag coefficients attained at each advance ratio. The performance of the 94 percent tapered rotor was generally between that of the rectangular rotor and the 75 and 50 percent tapered rotors at each advance ratio for this range of rotor lift coefficients

Two-boxing is irrational

Philosophers debate whether one-boxing or two-boxing is the rational act in a Newcomb situation. I shall argue that one-boxing is the only rational choice. This is so because there is no intelligible aim by reference to which you can justify the choice of two-boxing over one-boxing once you have come to think that you will two-box (whereas there is such an aim by reference to which you can justify one-boxing). The only aim by which the agent in the Newcomb situation can justify his two-boxing is the subjunctively described aim of ‘getting more than I would if I were to one-box’. But such a subjunctively described aim can justify an action only if it can be seen as generating, in conjunction with the agent’s beliefs, an indicatively describable aim which justifies the action. In the case of the Newcomb agent the aim of 'getting more than I would if I were to one-box’ cannot be seen in this way

Low-speed aerodynamic characteristics of a 9.3-percent-thick supercritical airfoil section

An investigation was conducted in the Langley low turbulence pressure tunnel to determine the low-speed, two dimensional characteristics of a 9.3 percent-thick supercritical airfoil. The airfoil was tested at Reynolds numbers (based on chord) from 2.9 million to 16.8 million, at Mach numbers from 0.10 to 0.36, and at geometric angles of attack from -8 degrees to 14 degrees

Two-dimensional aerodynamic characteristics of several rotorcraft airfoils at Mach numbers from 0.35 to 0.90

An investigation was conducted in the Langley 6- by 28-inch transonic tunnel and the 6- by 19-inch transonic tunnel to determine the two-dimensional aerodynamic characteristics of several rotorcraft airfoils at Mach numbers from 0.35 to 0.90. The airfoils differed in thickness, thickness distribution, and camber. The FX69-H-098, the BHC-540, and the NACA 0012 airfoils were investigated in the 6- by 28-inch tunnel at Reynolds numbers (based on chord) from about 4.7 to 9.3 million at the lowest and highest test Mach numbers respectively. The FX69-H-098, the NLR-1, the BHC-540, and the NACA 23012 airfoils were investigated in the 6- by 19-inch tunnel at Reynolds numbers from about 0.9 to 2.2 million at the lowest and highest test Mach numbers respectively