'Jan. 7, 1947. ' S. S. KNOX 2,413,924 ' AIRCRAFT ms'mumanr m“ Oct. 26. 1944 2 Sheets-Shut 1 / I I.LI ' IN VEN TOR. 54/1062 8.’ Kvox *ATTOENE‘Y Jan.‘ 7, v1947. ' ‘ > s, s, KNOX ‘ R AIRCRAFT INSTRUMENT Filed‘ 0071;.‘ 25,. 1944 Aggie. 2,413,924 v I 2 ‘Sheets-Sheet 2 _ ‘ INVEN TOR. Sonata 6.’ M/ox. - Anne/(gr Patented Jan. 7, 1947 2,413,924 UNITED STATES PATENT OFFICE 2,413,924 AIRCRAFT INSTRUMENT Samuel S. Knox, Long Beach, Calif. ‘Application October 26, 1944, Serial No. 560,505 7 Claims. (Cl. 244-4) 1 This invention has to do with an aircraft in strument and is more speci?cally concerned with an instrument or unit of apparatus for indicat 2 involves elements that are extremely simple and inexpensive of manufacture and when once in stalled are not subject to improper operation. ing the operative relationship between the Another object of my invention is to provide a ground and the landing wheels of an aeroplane, 5 visual or optical instrument of the general char and it is a general object of the present inven acter hereinabove referred to, operable at night tion to provide a simple, practical, effective in as well as during the day. My invention pro» strument of this general character. vides illuminating means making the instrument In landing aeroplanes, and particularly when useful even though the parts to be viewed are handling large aeroplanes, di?culties are fre 10 not illuminated by daylight. quently encountered when there is a substantial Another object of my invention is to provide diiference between the rotational speed of the coordination between the aeroplane and the treads of the landing wheels and the movement ground or landing ?eld, whereby the pilot can of the plane over the ground, commonly termed accurately estimate the ground speed and where the ground speed. 15 by the pilot is able to accurately compare the To facilitate landing various means have been ground speed with that of the wheels of the proposed and used to eifect pro-rotation of the aeroplane. With the information gained through landing wheels of planes so that the rotational the present apparatus the pilot can easily op speeds of the peripheries of the wheels are sub erate or regulate the pre-rotation units of the stantially equal to the ground speed or to the aeroplane wheels to gain almost perfect synchro speed of movement of the plane relative to the nism for landing. ground. Even with such pre-rotation of the The various objects and features of my inven landing wheels di?iculties are experienced due tion will be fully understood from the following to diiferences in speed between the several land detailed description of a typical preferred form ing wheels, and due to the fact that it is practi 25 and application of the invention, throughout cally impossible to gain exactly the same speed which description reference is made to the ac between the wheels and the ground. Reliance companying drawings, in which: of a pilot upon pre-rotation is very likely to ‘ Fig. 1 is a plan view of a typical unit of ap cause difficulty, whereas if the pilot is fully ap paratus embodying the present invention, show prized of the lack of synchro-nism in the various so ing the manner in which such unit is related to factors involved he is prepared to handle the a typical aeroplane. Fig. 2 is a front end view aeroplane accordingly. of the apparatus of the present invention like It is a general object of my present invention wise indicating its application to a typical aero to provide an instrument whereby a pilot can plane. Fig. 3 is an enlarged detailed sectional instantaneously ascertain the relationship of the 35 view of one portion of the apparatus that I have factors hereinabove referred to so that he has provided. Fig. 4 is a detailed sectional view taken the information necessary to make a safe and substantially as indicated by line 4—ll on Fig. 2. proper landing. With the knowledge gained Fig. 5 is an enlarged plan view taken as indi from the instrument I have provided the shock cated by line 5-5 on Fig. ll. Fig. 6 is a sectional of landing can be minimized, making landings 40 view taken as indicated by line li—ii on Fig. 4. safe and making it possible to lighten plane con Fig. 7 is a view showing an aeroplane on a land struction. . ing ?eld marked for coordination with the ap It is another object of my invention to provide paratus on the aeroplane. Fig. 8 is a perspective apparatus such as I have referred to which is view of one wheel of the aeroplane at the ground an optical instrument, or in which the factors or landing ?eld and showing the relationship of are communicated to the pilot visually, making it the markings provided on the wheel and ?eld. unnecessary for him to read or compare instru ments or indicators, such ,as speedometers or The‘instrument that I have provided is useful, generally, on aircraft to facilitate the landing other like devices. thereof. The invention is particularly usefu1 on Another object of the invention is to provide 50 aeroplanes or heavier than air craft which have an instrument of the general character herein to be landed at high speeds. In the drawings above referred to which is wholly free of me~ I have shown but one simple typical form of the chanically moving or operating parts compli invention and have indicated such form of the cated or expensive of manufacture or subject to invention as applied to a typical aeroplane. The failure. The instrument that I have provided 55 aeroplane indicated, in the drawings includes a 2,413,924 3 fuselage A with a pilot’s compartment at B, land ing wheels C located beneath wing W in opposite directions from or at either side of the fuselage, the wheels C being carried by a suitable support ing gear D so that they are retractable and so that they are spaced a substantial distance apart laterally of the plane when lowered to be in op erating position, as shown in Fig. 2 of the draw 4 upwardly through the tube to be passed there from into the duct Y in case [2. In the arrangement illustrated the viewing de vice IQ is located between the wheels C and for ward thereof and, therefore, each light conveying tube provided for receiving light from a wheel C has an outer end portion 39 which is vertically disposed over the wheel, a horizontal and in wardly extending lateral portion 3| which joins The present invention also coordinates the 10 the upper end of the portion B? and extends to a point near the center of the aeroplane, a for aeroplane with the landing field by relating ref mgs. erence marks E on the wheels C with reference wardly extending axial portion 32 which projects forward from the inner end of the lateral por tion 3|, and a vertical inner end portion 33 which extends upwardly from the forward end of the axial portion 32. The outer portion 33 of each tube is preferably located to point to or to face the center of the wheel at which it is located. can be corrected by suitable operation of the pre The upper ends of the tube portions 33 com rotation units G provided for the wheels. The instrument that I have provided involves, 20 municate with ducts of the case I2 of means it, the said portion of one such light conveying tube generally, what I will term a viewing device I0 communicating with duct X while the said por located so that it can be readily observed by the marks F on the ?eld. The reference marks with the aid of the instrument I have provided gives the pilot accurate information as to the speed of the wheels relative to the ground speed of the aeroplane so that any appreciable discrepancy pilot in the pilot compartment B of the plane, tion of the other light conveying tube communi and means II for projecting images of several cates with duct Z. I provide re?ectors 45 at the corners where the different objects into the viewing device to be there visible in side by side relationship for im mediate comparison. In large aeroplanes that carry a pilot, a co-pilot and a ?ight engineer, the viewing device can be light conveying tube portions join so that light entering the upper ends of the tube portions 30 is reflected through the several portions of the tubes to enter the ducts X and Z. placed so that it will be operated by the flight 30 The means I I includes in addition to the tubes engineer at times when not on automatic control. hereinabove described a condensing lens 4: in In practice the essential elements of the inven connection with each tube, preferably where it tion will vary with the number and location of the objects to be viewed and with the structure of the aeroplane in which the instrument is in corporated. In an ordinary situation such as I have illustrated in the drawings the pilot or other joins a duct of the means [9, the several lenses being such as to receive images from the tubes and throw or project them through the ducts of case l2 onto the ground glass [3. It is to be understood that the tubes or various person utilizing the information is supplied with light conveying parts may, in practice, he of any the desired information when supplied with a desired shape or cross sectional con?guration. In view of each of the two wheels C and the ground 40 the preferred form of the invention the several over which the aeroplane is traveling. In this tubes of the means ll may be made fairly large particular case the viewing device is such as to in cross sectional extent to pass a substantial provide three images to be Viewed by the pilot, amount of light, and it may not be desirable to and there are three separate parts to the means cast images on the ground glass as large as the l'l, one for projecting an image of the ground cross sectional areas of the tubes. In such case over which the plane is operating and one for the case l2 may be made tapered or convergent projecting an image of each wheel C. so that the end where the ground glass is located The particular viewing device shown in the is substantially smaller than the end to which the drawings involves, generally, a case I2, tubular in several tubes of means H are joined, and the form and provided at its upper end with a screen lenses 4! provided in the means Il may be de or ground glass IS. The tubular case is provided signed to cast images of the desired size on the with partitions M which extend longitudinally therein and divide the case into three light ducts or passages X, Y and Z. The light ducts extend from the lower end of the case to the upper end where they are open to the ground glass I3. Each of the several separate parts of the means H] includes a light conveying tube having one end facing an object to be viewed and the other end facing one of the light ducts of the means Ill. The light conveying tubes will, in practice, vary in shape and extent depending upon the rela ground glass 13. In practice it is advantageous that the move ments indicated on the ground glass l3, that is the images of the wheels and of the ground, should appear to be in the same direction so that the pilot can readily compare them. To accom plish this when the arrangement is such as I have shown in the drawings I provide a reversing prism 50 in the tube passing the image of the ground so that this image is reversed as otherwise it would be moving in a direction opposite to that of the tionship of the means IE! to the parts to be viewed. wheels. In the particular case illustrated, which is a typi In accordance with the preferred form of my cal case, the tube 20 of one part of means H de 65 invention I provide a source of light, preferably a signed to face the ground over which the plane small spot-light, 60 at or near the outer end of is operated, may be a straight tube extending each of the tubes 20 of means II and the lights downwardly from one of the light ducts of means are focused and directed so that when they are H1, preferably the center light duct Y of the energized they shine brightly upon the spot from means If), as shown in Fig. 2 of the drawings. which light is desired to be re?ected into the This light conveying tube 20 is joined to the case tubes. For instance the light on the center tube [2 of means Ill and is open at each end and is which faces the ground shines downwardly onto free of obstructions so that light reflected from the ground immediately under that tube, where the ground over which the plane is traveling en ters the open lower end of the tube and passes 75 as the other lights shine onto the wheels 0 imme 2,413,924 53 , diatelyunder or inline with the light conveying tubes facing the wheels.’ ‘ ’ ‘ i . 6 . this connection, insofar as mypresent invention is concerned.‘ ' ‘ ' " _ In accordance with my invention I coordinate the aeroplane to the landing ?eld so that the pilot It will be apparent from the foregoing descrip tion thatthe apparatus may be made wholly or operators of the aeroplane can accurately de .5 automatic, that is, through electronic means or termine the relationship between the speed of other suitable means the ?ashing effect gained rotation of the wheels of the aeroplane and the at the ground glasses‘ of the viewing device can land ‘speed of the aeroplane. This phase of my be utilized as the means or medium for effecting invention will be best understood from ‘a‘ consid eration of Figs. 7 and 8 of the drawings. In accordance with my invention I provide a landing ?eld ‘Hl'with a series of markings or what I will term reference marks ‘II which extend adjustment of the pre-rotation units. For in stance, an electronic unit or units‘ can be provided to operate under control of the ?ashes at the ground glasses to regulate the control levers 92 or equivalent control parts of the'pre-rotation units transversely of the direction in which aeroplanes _ so that the‘ pre-rotating means are automatically are to be landed. The reference marks may be 15 adjusted so that the wheels of the aeroplane are operating in true synchronism with the ground formed on the surface of the ?eld ‘ill in anysuit speed when the aeroplane reaches the ground. able manner so long as they optically differentiate With the apparatus that I have provided light from the background or balance of .the ?eld.’ _ In practice they may be permanent markings or they from the several objects, that is, from the two may be markings such as are commonly used on wheels C and from the surface of the landing playing ?elds to designate areas of such ?elds. ?eld immediately under the plane, is reflected through the tubes of the means I I and is directed The markings ‘HI may extend a substantial dis between lenses 4| so that several images are tance along the ?eld and may be provided from one end of the ?eld to the other. The markings are lines of suitable width and are uniformly dis posed transversely of the direction or length of thrown on the ground glass l3. These several they are uniformly spaced and have a spacing images, characterized by the ?ashes or flash-like effect gained by the provision of the reference marks on the ?eld and wheels, give the pilot a view of the objects to which the tubes of the de?nitely related to the aeroplane. means H are faced and as the pilot is landing the ?eld and, in accordance with my invention, ~ In accordance with my invention I relate the 30 he can glance at the ground glass where the images are projected and if there is a substantial spacing of the reference marks 1| on the landing lack of synchronism between the wheels or be ?eld to reference marks 12 on the landing wheels tween the wheels and ground speed, he can op of the aeroplane. In the preferred form of my erate the controls of the pre-rotating means to invention I provide a. single reference mark on , bring about the necessary correction. For in the peripheral portion of each landing wheel, stance, in the case illustrated in the drawings preferably a mark extending across the tread the pilot can instantaneously view images of the portion of the wheel, as shown in the drawings, ?eld immediately under the plane and the treads and in the preferred relationship between the ref~ of the two wheels C. If there is any substantial erence marks on the landing wheels and those on the landing ?eld the marks on the ?eld are spaced 40 discrepancy or variation between the relative speeds of these objects the pilot will be aware apart a distance equal to the circumference of the of that fact and in making a landing can either wheels. vary or manipulate the pre-rotation equipment, When the reference marks are used on the if that is possible, or can handle the plane to wheels of the aeroplane and the landing ?eld the 45 make the necessary compensations. Viewing apparatus that I have described above From the foregoing description it will be ap will give a person in the aeroplane a view of the parent that I have provided an optical instru reference marks somewhat in the nature of ment which is entirely free of working or moving ?ashes as the marks pass the viewing parts. For parts subject to failure or which are heavy and instance, as eachwheel revolves there will be a 50 complicated. The apparatus that I have pro flash on the ground glass viewing that wheel each vided, when once properly installed, remains time the wheel turns, and in like fashion as the static and is at all times available for use. Fur aeroplane moves over the ground or landing ?eld ther, it is important that the instrument that the reference marks thereon will give ?ashes as I have provided is wholly optical and is such the viewing apparatus passes over them. A per 55 that a pilot can read it instantaneously and does son in the aeroplane can readily observe the flash not have to compare numerous dials or instru ing effect gained by the reference marks on the ment readings in order to ascertain the informa two wheels and can bring the Wheels into proper tion desired. synchronism and the speed of both wheels can be Having described only a typical preferred form brought into proper synchronism with the ground 60 and application of my invention, I do not wish speed through the knowledge gained by the to be limited or restricted to the speci?c details ?ashes appearing at the viewing device. herein set forth, but wish to reserve to myself In the drawings I have indicated a pro-rotating any variations or modi?cations that may appear unit G at each landing wheel and have shown a to those skilled in the art or fall within the control 96 in the aeroplane adjacent the viewing 65 scope of the following claims. unit 10. I have indicated the control 90 coupled Having described my invention, I claim: with each unit G by a suitable control connection 1. A landing ?eld for aeroplanes, the ?eld hav 9! and have shown individual control levers 92 at ing a series of normally visible uniform and the controlS? so that the wheels can be indi equally spaced reference marks thereon extend vidually controlled. It is to be understood that 70 ing transverse of the direction in which aero my present invention is in no way concerned with planes land thereon. the means or mechanism used for effecting pre 2. A landing ?eld for aeroplanes, the ?eld hav rotaticn of the wheels, nor with the means em ing a series of reference marks thereon extend ployed for effecting control of the pre-rotating ing transverse of the direction in which aero means. Any suitable apparatus can be used in 75 planes land thereon, the marks being uniformly artisans rection and being ‘such as 'tocoritrast optically With‘the balanceof the ?eld, ' " ~ ' ' and. a viewing device for, viewing the, field and " 3., A landing, ?eld for aeroplanes, the field; the, which aeroplanes land'thereon, themarksbeing ' 10 ' ' ’ controllable means for pre-rotating the wheels, and a viewing devicerfor simultaneously viewing erencefrnarks‘ thereon,’ and. an, aeroplane with landing wheels having reference marksthereon at the peripheral portions thereof, controllable means for pie-rotating‘ the wheels, and a view ' ingjdevipe for, viewing the ?eld and thewheels. 5. In combination a‘ landing, ?eld‘having a series of spaced transversely‘ disposed visible ref erence marks thereon, and an aeroplane with " 7.‘ In clornhinationv 'a_ landing‘ ?eld having a aeroplane can view a‘ parttofl the ?eld and,‘ ob serve the reference, marks asthe aeroplane ap v ' ” seriesof; Spaced transversely. disposed-visible ref erence marks thereon,)and_ an aeroplane with an optical viewing, device whereby a person, in vthe ' ' of the wheels bearingv the reference, marks. series of spaced transversely disposed, visib'le' ref, ' ‘ the ?eld beneath, the, aeroplane and the portions ' . 4,. In combination a landing field‘ having a proaches a landing-on the ?eld. ' series of spaced transversely disposed visible ref erencefmarks thereon, and, an,‘ aeroplane with landing wheels. having reference marks; thereon, spaced apart distances substantially-V equal to the planes to land‘ on, the ?eld. wheels. Q. In.‘combinationv a landing ?eld having a having a: series off normally visible reference marks thereon all extending, in the‘, ‘same,’ direc tion and extending transverse.- of; the, direction in, circumference of the landing. wheels of aero 8 landing. wheels‘, having reference marks. thereon, controllable means for 'preerotating the wheels, spaced. apart, and all; extend-121g‘; 1;“- t‘hei same ‘dis 20 SAMUEL s. KNOX.