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 Serial/Series Title: NACA Advanced Confidential Report
 Serial/Series Title: NACA Special Report
 Collection: National Advisory Committee for Aeronautics Collection
A Brief Study of the Speed Reduction of Overtaking Airplanes by Means of Air Brakes, Special Report

A Brief Study of the Speed Reduction of Overtaking Airplanes by Means of Air Brakes, Special Report

Date: May 1, 1942
Creator: Pearson, H. A. & Amderspm. R. F.
Description: As an aid to airplane designers interested in providing pursuit airplanes with decelerating devices intended to increase the firing time when overtaking another airplane, formulas are given relating the pertinent distances and speeds in horizontal flight to the drag increase required. Charts are given for a representative parasite-drag coefficient from which the drag increase, the time gained, and the closing distance may be found. The charts are made up for three values of the ratio of the final speed of the pursuing airplane to the speed of the pursued airplane and for several values of the ratio of the speed of the pursued airplane to the initial speed of the pursuing airplane. Charts are also given indicating the drag increases obtainable with double split flaps and with conventional propellers. The use of the charts is illustrated by an example in which it is indicated that either double split flaps or, under certain ideal conditions, reversible propellers should provide the speed reductions required.
Contributing Partner: UNT Libraries Government Documents Department
Compressibility Effects in Aeronautical Engineering

Compressibility Effects in Aeronautical Engineering

Date: August 1, 1941
Creator: Stack, John
Description: Compressible-flow research, while a relatively new field in aeronautics, is very old, dating back almost to the development of the first firearm. Over the last hundred years, researches have been conducted in the ballistics field, but these results have been of practically no use in aeronautical engineering because the phenomena that have been studied have been the more or less steady supersonic condition of flow. Some work that has been done in connection with steam turbines, particularly nozzle studies, has been of value, In general, however, understanding of compressible-flow phenomena has been very incomplete and permitted no real basis for the solution of aeronautical engineering problems in which.the flow is likely to be unsteady because regions of both subsonic and supersonic speeds may occur. In the early phases of the development of the airplane, speeds were so low that the effects of compressibility could be justifiably ignored. During the last war and immediately after, however, propellers exhibited losses in efficiency as the tip speeds approached the speed of sound, and the first experiments of an aeronautical nature were therefore conducted with propellers. Results of these experiments indicated serious losses of efficiency, but aeronautical engineers were not seriously concerned at the ...
Contributing Partner: UNT Libraries Government Documents Department
Determination of Flight Paths of an SBD-1 Airplane in Simulated Diving Attacks, Special Report

Determination of Flight Paths of an SBD-1 Airplane in Simulated Diving Attacks, Special Report

Date: March 1, 1943
Creator: Johnson, Harold I.
Description: An investigation has been made to determine the motions of and the flight paths describe by a Navy dive-bombing airplane in simulated diving attacks. The data necessary to evaluate these items, with the exception of the atmospheric wind data, were obtained from automatic recording instruments installed entirely within the airplane. The atmospheric wind data were obtained from the ground by the balloon-theodolite method. The results of typical dives at various dive angles are presented in the form of time histories of the motion of the airplane as well as flight paths calculated with respect to still air and with respect to the ground.
Contributing Partner: UNT Libraries Government Documents Department
The Effect of Compressibility on the Growth of the Laminar Boundary Layer on Low-Drag Wings and Bodies

The Effect of Compressibility on the Growth of the Laminar Boundary Layer on Low-Drag Wings and Bodies

Date: January 1, 1943
Creator: Allen, H. Julian & Nitzberg, Gerald E.
Description: The development of the laminar boundary layer in a compressible fluid is considered. Formulas are given for determining the boundary-layer thickness and the ratio of the boundary-layer Reynolds number to the body Reynolds number for airfoils and bodies of revolution. It i s shown that the effect of compressibility will profoundly alter the Reynolds number corresponding to the upper limit of the range of the low-drag coefficients . The available data indicate that for low-drag and high critical compressibility speed airfoils and bodies of revolution, this effect is favorable.
Contributing Partner: UNT Libraries Government Documents Department
Effects of Direction of Propeller Rotation on the Longitudinal Stability of the 1/10-Scale Model of the North American XB-28 Airplane with Flaps Neutral, Special Report

Effects of Direction of Propeller Rotation on the Longitudinal Stability of the 1/10-Scale Model of the North American XB-28 Airplane with Flaps Neutral, Special Report

Date: June 1, 1942
Creator: Delany, Noel K.
Description: The effects of direction of propeller rotation on factors affecting the longitudinal stability of the XB-28 airplane were measured on a 1/10-scale model in the 7- by 10-foot tunnel of the Ames Aeronautical Laboratory. The main effect observed was that caused by regions of high downwash behind the nacelles (power off as well as power on with flaps neutral). The optimum direction of propeller rotation, both propellers rotating up toward the fuselage, shifted this region off the horizontal tail and thus removed its destabilizing effect. Rotating both propellers downward toward the fuselage moved it inboard on the tail and accentuated the effect, while rotating both propellers right hand had an intermediate result. Comparisons are made of the tail effects as measured by force tests with those predicted from the point-by-point downwash and velocity surveys in the region of the tail. These surveys in turn are compared with the results predicted from available theory.
Contributing Partner: UNT Libraries Government Documents Department
Flight Measurements of the Aileron Characteristics of a Grumman F4F-3 Airplane

Flight Measurements of the Aileron Characteristics of a Grumman F4F-3 Airplane

Date: September 1, 1942
Creator: Kleckner, Harold F.
Description: The aileron characteristics of a Grumman F4F-3 airplane were determined in flight by means of NACA recording and indicating instruments. The results show that the ailerons met NACA minimum requirements for satisfactory control throughout a limited speed range. A helix angle of approximately 0.07 radian was produced with flaps down at speeds from 90 to 115 miles per hour indicated airspeed and with flaps up from 115 to 200 miles per hour. With flaps up at 90 miles per hour, the helix angle dropped to 0.055 radian; above 200 miles per hour heavy aileron stick forces seriously restricted maneuverability in roll.
Contributing Partner: UNT Libraries Government Documents Department
NACA Radio Ground-Speed System for Aircraft, Special Report

NACA Radio Ground-Speed System for Aircraft, Special Report

Date: February 1, 1943
Creator: Hastings, Charles E.
Description: A method that utilizes the Doppler effect on radio signals for determining the speed of an airplane and the distance traveled by the airplane has been developed and found to operate satisfactorily. In this method, called the NACA radio ground-speed system, standard readily available radio equipment is used almost exclusively and extreme frequency stability of the transmitters is not necessary. No complicated equipment need be carried in the airplane, as the standard radio transmitter is usually adequate. Actual flight tests were made in which the method was used and the results were consistent with calibrated air speed indications and stop-watch measurements. Inasmuch as the fundamental accuracy of the radio method is far better than either of the checking systems used, no check was made on the limitations of the accuracy.
Contributing Partner: UNT Libraries Government Documents Department
Preliminary Investigation of the Effect of Compressibility on the Maximum Lift Coefficient, Special Report

Preliminary Investigation of the Effect of Compressibility on the Maximum Lift Coefficient, Special Report

Date: February 1, 1943
Creator: Stack, John; Fedziuk, Henry A. & Cleary, Harold E.
Description: Preliminary data are presented on the variation of the maximum lift coefficient with Mach number. The data were obtained from tests in the 8-foot high-speed tunnel of three NACA 16-series airfoils of 1-foot chord. Measurements consisted primarily of pressure-distribution measurements in order to illustrate the nature of the phenomena. It was found that the maximum lift coefficient of airfoils is markedly affected by compressibility even at Mach numbers as low as 0.2. At high Mach numbers pronounced decrease of the maximum lift coefficient was found. The magnitude of the effects of compressibility on the maximum lift coefficient and the low speeds at which these effects first appear indicate clearly that consideration of the take-off thrust for propellers will give results seriously in error if these considerations are based on the usual low-speed maximum-lift-coefficient data generally used.
Contributing Partner: UNT Libraries Government Documents Department
Preliminary Wind-Tunnel Tests of the Effect of Nacelles on the Characteristics of a Twin-Engine Bomber Model with Low-Drag Wing, Special Report

Preliminary Wind-Tunnel Tests of the Effect of Nacelles on the Characteristics of a Twin-Engine Bomber Model with Low-Drag Wing, Special Report

Date: July 1, 1942
Creator: Wenzinger, Carl J. & Sivells, James C.
Description: Tests were made in the NACA 19-foot pressure tunnel of a simplified twin-engine bomber model with an NACA low-drag wing primarily to obtain an indication of the effects of engine nacelles on the characteristics of the model both with and without simple split trailing-edge flaps. Nacelles with conventional-type cowlings representative of those used on an existing high-performance airplane and with NACA high-speed type E cowlings were tested. The tests were made without propeller slipstream. The aerodynamic effects of adding the nacelles to the low-drag wing were similar to the effects commonly obtained by adding similar nacelles to conventional wings. The maximum lift coefficient without flaps was slightly increased, but the increment in maximum lift due to deflecting the flaps was somewhat decreased. The stalling characteristics were improved by the presence of the nacelles. Addition of the nacelles had a destabilizing effect on the pitching moments, as is usual for nacelles that project forward of the wing. The drag increments due to the nacelles were of the usual order of magnitude, with the increment due to the nacelles with NACA type E cowlings approximately one-third less than that of the nacelles with conventional cowlings with built-in air scoops.
Contributing Partner: UNT Libraries Government Documents Department
A profile-drag investigation in flight on an experimental fighter-type airplane the North American XP-51

A profile-drag investigation in flight on an experimental fighter-type airplane the North American XP-51

Date: January 1, 1942
Creator: Zalovcik, J. A.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
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