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NACA Advanced Confidential Report
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National Advisory Committee for Aeronautics Collection
- Investigation of flow in an axially symmetrical heated jet of air
- The work done under this contract falls essentially into two parts: the first part was the design and construction of the equipment and the running of preliminary tests on the 3-inch jet, carried out by Mr. Carl Thiele in 1940; the second part consisting in the measurement in the 1-inch jet flow in an axially symmetrical heated jet of air. (author). digital.library.unt.edu/ark:/67531/metadc65451/
- Tests If a Highly Cambered Low-Drag-Airfoil Section with a Lift-Control Flap, Special Report
- Tests were made in the NACA two-dimensional low turbulence pressure tunnel of a highly cambered low-drag airfoil (NACA 65,3-618) with a plain flap designed for lift control. The results indicate that such a combination offers attractive possibilities for obtaining low profile-drag coefficients over a wide range of lift coefficients without large reductions of critical speed. digital.library.unt.edu/ark:/67531/metadc65162/
- NACA Radio Ground-Speed System for Aircraft, Special Report
- 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. digital.library.unt.edu/ark:/67531/metadc65161/
- Wind-Tunnel Development of Ailerons for the Curtiss XP-60 Airplanem Special Report
- An investigation was made in the LWAL 7- by 10-foot tunnel of internally balanced, sealed ailerons for the Curtiss XP-60 airplane. Ailerons with tabs and. with various amounts of balance were tested. Stick forces were estimated for several aileron arrangements including an arrangement recommended for the airplane. Flight tests of the recommended arrangement are discussed briefly in an appendix, The results of the wind-tunnel and flight tests indicate that the ailerons of large or fast airplanes may be satisfactorily balanced by the method developed. digital.library.unt.edu/ark:/67531/metadc65169/
- Paths of Target Seeking Missiles in Two Dimensions
- Parameters that enter into equation of trajectory of a missile are discussed. Investigation is made of normal pursuit, of constant, proportional, and line--of-sight methods of navigation employing target seeker, and of deriving corresponding pursuit paths. Pursuit paths obtained under similar conditions for different methods are compared. Proportional navigation is concluded to be best method for using target seeker installed in missile. digital.library.unt.edu/ark:/67531/metadc65596/
- A Brief Study of the Speed Reduction of Overtaking Airplanes by Means of Air Brakes, Special Report
- 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. digital.library.unt.edu/ark:/67531/metadc65165/
- Determination of Flight Paths of an SBD-1 Airplane in Simulated Diving Attacks, Special Report
- 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. digital.library.unt.edu/ark:/67531/metadc65195/
- Wind-Tunnel Investigation of an NACA Low-Drag Tapered Wing with Straight Trailing Edge and Simple Split Flaps, Special Report
- An investigation was conducted in the NACA 19-foot pressure wind tunnel of a tapered wing with straight railing edge having NACA 66 series low-drag airfoil sections and equipped with full-span and partial-span simple split flaps. The airfoil sections used were the NACA 66,2-116 at the root and the 66,2-216 at the tip. The primary purpose of the investigation was to determine the effect of the split flaps on the aerodynamic characteristics of the tapered wing. Complete lift, drag, and pitching-moment coefficients were determined for the plain wing and for each flap arrangement through a Reynold number range of 2,600,000 to 4,600,000. The results of this investigation indicate that values of maximum lift coefficient comparable to values obtained on tapered wings with conventional sections and similar flap installations can be obtained from wings with the NACA low-drag sections. The increment of maximum lift due to the split flap was found to vary somewhat with Reynold number over the range investigated. The C(sub L)max of the wing alone is 1.49 at a Reynolds number of 4,600,000; whereas with the partial-span simple split flap it is 2.22 and with the full-span arrangement, 2.80. Observations of wool tufts on the wing indicate that the addition of split flaps did not appreciable alter the pattern of the stall; even though the stall did occur more abruptly than with the wing alone. digital.library.unt.edu/ark:/67531/metadc65192/
- Preliminary Investigation of the Effect of Compressibility on the Maximum Lift Coefficient, Special Report
- 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. digital.library.unt.edu/ark:/67531/metadc65198/
- Tests of an NACA 66,2-420 Airfoil of 5-Foot Chord at High Speed, Special Report
- This report covers tests of a 5-foot model of the NACA 66,2-420 low-drag airfoil at high speeds including the critical compressibility speed. Section coefficients of lift, drag, and pitching moment, and extensive pressure-distribution data are presented. The section drag coefficient at the design lift coefficient of 0.4 increased from 0.0042 at low speeds to 0.0052 at a Mach number of 0.56 (390 mph at 25,000 ft altitude). The critical Mach number was about 0.60. The results cover a Reynold number range from 4 millions to 17 millions. digital.library.unt.edu/ark:/67531/metadc65196/
- 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
- 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. digital.library.unt.edu/ark:/67531/metadc65184/
- Study of Turning Performance of a Fighter-Type Airplane Particularly as Affected by Flaps and Increased Supercharging, Special Report
- Results of a study to determine the effects on turning performance due to various assumed modifications to a typical Naval fighter airplane are presented. The modifications considered included flaps of various types, both part and full space, increased supercharging, and increased wing loading. The calculations indicated that near the low-speed end of the speed range, the turning performance, as defined by steady level turns at a given speed, would be improved to some extent by any of the flaps considered at altitudes up to about 25,000 feet. (If turning is not restricted to the conditions of no loss of speed or altitude, more rapid turning can, of course, be accomplished with the aid of flaps, regardless of altitude.) Fowler flaps and NACA slotted flaps appeared somewhat superior to split or perforated split flaps for maneuvering purposes, particularly if the flap position is not adjustable. Similarly, better turning performance should be realized with full-span than with part-span flaps. Turning performance over the lower half of the speed range would probably not be materially improved at any altitude by increased supercharging of the engine unless the propeller were redesigned to absorb the added power more effectively; with a suitable propeller the turning performance at high altitudes could probably be greatly improved with increased supercharging. A reduction in wing area with the aspect ratio held constant would result in impairment of turning performance over practically the entire speed range at all altitudes. digital.library.unt.edu/ark:/67531/metadc65186/
- Preliminary Wind-Tunnel Tests of the Effect of Nacelles on the Characteristics of a Twin-Engine Bomber Model with Low-Drag Wing, Special Report
- 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. digital.library.unt.edu/ark:/67531/metadc65177/
- The Effect of Compressibility on the Growth of the Laminar Boundary Layer on Low-Drag Wings and Bodies
- 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. digital.library.unt.edu/ark:/67531/metadc65159/
- Flight Measurements of the Aileron Characteristics of a Grumman F4F-3 Airplane
- 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. digital.library.unt.edu/ark:/67531/metadc65202/
- An Experimental Investigation of NACA Submerged-Duct Entrances
- The results of a preliminary investigation of submerged duct entrances are presented. It is shown that an entrance of this type possess desirable critical speed and pressure recovery characteristics when used on a fuselage or nacelle in a region of low incremental velocity and thin boundary layer. The data obtained indicate that submerged entrances are most suitable for use with internal-flow systems which diffuse the air only a small amount: for example, those used with jet motors which have axial-flow compressors. Where complete diffusion of the air is required, fuselage-nose or wing leading edge inlets may prove to be superior. The results of the investigation have been prepared in such a form as to permit their use by a designer and the application of these data to a specific design is discussed. digital.library.unt.edu/ark:/67531/metadc64879/
- Compressibility Effects in Aeronautical Engineering
- 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 time became it was generally possible. to design propellers with quite low tip. speeds. With the development of new engines having increased power and rotational speeds, however, the problems became of increasing importance. digital.library.unt.edu/ark:/67531/metadc64993/
- Radiator Design and Installation - II, Special Report
- A mathematical analysis of radiator design has been made. The volume of the radiator using least total power has been expressed in a single formula which shows that the optimum radiator volume is independent of the shape of the radiator and which makes possible the construction of design tables that give the optimum radiator volume per 100-horsepower heat dissipation as a function of the speed, of the altitude, and of one parameter involving characteristics of the airplane. Although, for a given set of conditions, the radiator volume using the least total power is fixed, the frontal area, or the length of the radiator needs to be separately specified in order to satisfy certain other requirement such as the ability to cool with the pressure drop available while the airplane is climbing. In order to simplify the specification for the shape of the radiator and in order to reduce the labor involved in calculating the detailed performance of radiators, generalized design curves have been developed for determining the pressure drop, the mass flow of air, and the power expended in overcoming the cooling drag of a radiator from the physical dimensions of the radiator. In addition, a table is derived from these curves, which directly gives the square root of the pressure drop required for ground cooling as a function of the radiator dimensions, of the heat dissipation and of the available temperature difference. Typical calculations using the tables of optimum radiator volume and the design curves are given. The jet power that can be derived from the heated air is proportional to the heat dissipation and is approximately proportional to the square of the airplane speed and to the reciprocal of the absolute temperature of the atmosphere. A table of jet power, per 100 horsepower of heat dissipation at various airplane speeds and altitudes is presented. digital.library.unt.edu/ark:/67531/metadc65172/
- An Experimental Investigation of Several Low-Drag Wing-Nacelle Combinations with Internal Air Flow
- The results of an experimental investigation of several low-drag wing-nacelle combinations, incorporating internal air-flow systems, are presented. The external-drag increments due to these nacelles are between one-half and two-thirds of those of conventional nacelle forms. This improvement is accomplished with only minor effects on the lift and moment characteristics of the wing. The procedure employed to determine the external shape of such low-drag nacelles is considered in detail. The design of an efficient internal-flow system with or without a blower or throttle, presents no serious problems. The energy losses in the expansion before the engine and the contraction thereafter can be kept small. It is believed that these nacelles have a wide application in housing engine pusher-propeller units and, with some alteration, jet-propulsion devices. It is probable that the low external drags may not be realized if such nacelles are used with a tractor propeller because of the high level of turbulence in the propeller slipstream. digital.library.unt.edu/ark:/67531/metadc64992/
- Data for Design of Entrance Vanes from Two-Dimensional Tests of Airfoils in Cascade
- As a part of a program of the NACA directed toward increasing the efficiency of compressors and turbines, data were obtained for application to the design of entrance vanes for axfax-flow compressors or turbines. A series of blower-blade sections with relatively high critical speeds have been developed for turning air efficiently from 0 deg to 80 deg starting with an axial direction. Tests were made of five NACA 65-series blower blades (modified NACA 65(216)-010 airfoils) and of four experimentally designed blower blades in a stationary cascade at low Mach numbers. The turning effectiveness and the pressure distributions of these blade sections at various angles of attack were evaluated over a range of solidities near 1. Entrance-vane design charts are presented that give a blade section and angle of attack for any desired turning angle. The blades thus obtained operate with peak-free pressure distributions. Approximate critical Mach numbers were calculated from the pressure distributions. digital.library.unt.edu/ark:/67531/metadc63062/
- The Supersonic Axial-Flow Compressor
- An investigation has been made to explore the possibilities of axial-flow compressors operating with supersonic velocities into the blade rows. Preliminary calculations showed that very high pressure ratios across a stage, together with somewhat increased mass flows, were apparently possible with compressors which decelerated air through the speed of sound in their blading. The first phase of the investigation was the development of efficient supersonic diffusers to decelerate air through the speed of sound. The present report is largely a general discussion of some of the essential aerodynamics of single-stage supersonic axial-flow compressors. As an approach to the study of supersonic compressors, three possible velocity diagrams are discussed briefly. Because of the encouraging results of this study, an experimental single-stage supersonic compressor has been constructed and tested in Freon-12. In this compressor, air decelerates through the speed of sound in the rotor blading and enters the stators at subsonic speeds. A pressure ratio of about 1.8 at an efficiency of about 80 percent has been obtained. digital.library.unt.edu/ark:/67531/metadc60311/
- An interim report on the stability and control of tailless airplanes
- No Description digital.library.unt.edu/ark:/67531/metadc60946/
- An analytical investigation of the effects of elevator-fabric distortion on the longitudinal stability and control of an airplane
- No Description digital.library.unt.edu/ark:/67531/metadc60987/
- Correlation of the drag characteristics of a P-51B airplane obtained from high-speed wind-tunnel and flight tests
- No Description digital.library.unt.edu/ark:/67531/metadc60838/
- A metallurgical investigation of a large forged disc of 19-9 DL alloy
- No Description digital.library.unt.edu/ark:/67531/metadc62273/
- Flight measurements of compressibility effects on a three-blade thin Clark Y propeller operating at constant advance-diameter ratio and blade angle
- No Description digital.library.unt.edu/ark:/67531/metadc62161/
- The effect of trailing-edge extension flaps on propeller characteristics
- No Description digital.library.unt.edu/ark:/67531/metadc62160/
- The theory of propellers I : determination of the circulation function and the mass coefficient for dual-rotating propellers
- No Description digital.library.unt.edu/ark:/67531/metadc62137/
- The theory of propellers II : method for calculating the axial interference velocity
- No Description digital.library.unt.edu/ark:/67531/metadc62138/
- Wind tunnel tests of ailerons at various speeds V : pressure distributions over the NACA 66,2-216 and NACA 23012 airfoils with various balances on 0.20-chord ailerons
- No Description digital.library.unt.edu/ark:/67531/metadc62593/
- Paths of target-seeking missiles in two dimensions
- No Description digital.library.unt.edu/ark:/67531/metadc62682/
- Stability and control force tests of four- and six-unit wing designs of low aspect ratio and 20 degree triangular plan form
- No Description digital.library.unt.edu/ark:/67531/metadc62680/
- Wind-tunnel investigation of ailerons on a low-drag airfoil III : the effect of tabs
- No Description digital.library.unt.edu/ark:/67531/metadc62491/
- An investigation of 0.15-chord ailerons on a low-drag tapered wing at high speeds
- No Description digital.library.unt.edu/ark:/67531/metadc62490/
- Comparison of yaw characteristics of a single-engine airplane model with single-rotating and dual-rotating propellers
- No Description digital.library.unt.edu/ark:/67531/metadc62165/
- Wind-tunnel investigation of ailerons on a low-drag airfoil I : the effect of aileron profile
- No Description digital.library.unt.edu/ark:/67531/metadc62496/
- Wind-tunnel investigation of ailerons on a low-drag airfoil II : the effect of thickened and beveled trailing edges
- No Description digital.library.unt.edu/ark:/67531/metadc62493/
- The knock-limited performance of several miscellaneous fuels blended with a base fuel I
- No Description digital.library.unt.edu/ark:/67531/metadc62432/
- Summary of data relating to the effects of wing machine-gun and cannon installations on the aerodynamic characteristics of airplanes
- No Description digital.library.unt.edu/ark:/67531/metadc62430/
- Supersonic-tunnel tests of projectiles in Germany and Italy
- No Description digital.library.unt.edu/ark:/67531/metadc62434/
- Comparison of calculated and experimental propeller characteristics for four-, six-, and eight-blade single-rotating propellers
- No Description digital.library.unt.edu/ark:/67531/metadc62159/
- Effect of the lift coefficient on propeller flutter
- No Description digital.library.unt.edu/ark:/67531/metadc62153/
- Considerations of wake-excited vibratory stress in a pusher propeller
- No Description digital.library.unt.edu/ark:/67531/metadc62151/
- Simple curves for determining the effects of compressibility on pressure drop through radiators
- No Description digital.library.unt.edu/ark:/67531/metadc62021/
- Investigations on laminar boundary-layer stability and transition on curved boundaries
- No Description digital.library.unt.edu/ark:/67531/metadc62701/
- Theory and application of hot-wire instruments in the investigation of turbulent boundary layers
- No Description digital.library.unt.edu/ark:/67531/metadc62409/
- Parameters determining performance of supersonic pilotless airplanes powered by ram-compression power planes
- No Description digital.library.unt.edu/ark:/67531/metadc62640/
- Knock-limited power outputs from a CFR engine using internal coolants II : six aliphatic amines
- No Description digital.library.unt.edu/ark:/67531/metadc62055/
- A method for the calculation of external lift, moment, and pressure drag of slender open-nose bodies of revolution at supersonic speeds
- No Description digital.library.unt.edu/ark:/67531/metadc62664/
- Blade design data for axial-flow fans and compressors
- No Description digital.library.unt.edu/ark:/67531/metadc62634/