Feb. 5, 1946. W. MM 2,394,180 POWER COMPUTER Filed Jan, 2, 1940 5. Sheets-Sheet

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INVENTOR(r LAW/S W. /MM.

ATTORNEY

Feb. 5, 1946. L. W. MM 2,394,180 POWER COMPUTER Filed Jan. 2, 1940 5 Sheets-Sheet 2

INVENTOR LAW/S W. W.M.

ATTORNEY Feb. 5, 1946. L. W. IMM 2,394,180 POWER COMPUTER Filed Jan, 2, 1940 5 Sheets-Sheet 3

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INVENTOR, AWS / /WM, 22a-1 ATTORNEY

Feb. 5, 1946. L. W. IMM 2,394,180 POWER COMPUTER Filled Jan. 2, 1940 5 Sheets-Sheet 4.

INVENTOR AAWS W /MM.

ATTORNEY

Feb. 5, 1946. L. W. IMM 2,394,180 POWER COMPUTER Filed Jan. 2, 1940 5 Sheets-Sheet 5 7

EFFECTIVEBRAKE MEAPRE SURE

?E.24 S. I03 5 12 I6

NANFOLÉPRESSURE AttföDÉ TEMPERATURESC.R

INVENTOR LAW/S W. /MM.

ATTORNEY

Patented Feb. 5, 1946 2,394,180

UNITED STATES PATENT OFFICE 2,394,180 POWER COMPUTER Lewis W. Imm, Glendale, Calif., assignor to Libra scope, incorporated, Burbank, Calif., a corpo ration of California Application January 2, 1940, Serial No. 311,982 11 Claims. (CI. 235-6i) The present invention relates to computing de the pilot to obtain rapidly and easily the effect . vices, and particularly to an instrument for COr on his engine performance of various values of relating a plurality of factors affecting internal R. P. M., M. P., A., and T. combustion engine efficiency and power output. Other objects are: - The invention is disclosed as embodied in a To coordinate instantaneously the effects of computer especially designed for use in aircraft, R. P. M., M. P., A., and T., on H. P., F. C., and where it is particularly useful because the pilot is B. M. E. P.; ordinarily occupied with the control of the ship To eliminate the necessity for calculations and and can not give attention to involved mathe the use of charts by the pilot or an engineering matical calculations calling for mental concen O officer in determining the proper adjustment of tration. Furthermore, in aircraft, many variable his engine; factors affecting engine efficiency are present, To give information to the operator so that he such as temperature and pressure alti can more efficiently operate the aircraft engines; tude, which are not of importance in other ap To enable the operator to predict accurately plications. s the effect of changing certain factors on the op Instruments are provided in aircraft to indicate eration of his engine; motor speed, manifold pressure, carburetor tem To give information to the operator so that he perature, and pressure altitude. From this data can secure maximum efficiency by making pos the horsepower output, rate of fuel consumption, sible operation near the preferred B. M. E. P. and brake must be com 20 rating of the engine; puted if the power plant is to be operated at To show, for any operating conditions, the rate maximum efficiency. Thereafter, as changes in of fuel consumption; any of the indicated factors occur, such as alti To give information to the operator so as to tude, a recomputation must be made in Order to enable him to adjust the speed and other factors determine the direction and extent of changes of the flight to the amount of gas available lin which must be made in other factors, such as his tanks; and manifold pressure, in order to maintain maxi To give information to the operator So that he mum efficiency at the desired power output. may minimize wear and stress on the engine parts The instrument embodying the present inven by operating in proper relation to the optimum tion hereinafter described will, when the pilot 30 B. M. E. P. values at any speed, sets pointers therein to scale values of revolutions The invention possesses numerous other ob per minute, manifold pressure, pressure altitude, jects and features of advantages, SOme of which, and carburetor temperature, as read from his together with the foregoing, will be set forth in instruments, mechanically coordinate these the following description of specific apparatus values and indicate immediately the values of . 35 embodying and utilizing this invention. It is to horsepower, fuel consumption, and brake mean be understood that the principles of the inven effective pressure at which his engine is operating. tion are applicable to other apparatus, however, In the following explanation and specification, and that it is not limited in any way to the the speed in revolutions per minute will be abbre showing of the present application, as various viated as R. P. M.; the manifold pressure in inches AO other embodiments of the invention may be of mercury as M. P.; the pressure altitude effect adopted within the scope of the appended claims. in feet as A.; the brake mean effective pressure, a These objects, and the following description, figure of merit derived by averaging the may be better understood by reference to the pressure over the entire firing , will be in drawings, wherein: -- dicated in pounds per square inch, as B.M. E. P.; 4. Figure 1 is a plan view, taken from the rear, carburetor temperature in degrees Fahrenheit of the mechanical linkages of my device; will be abbreviated as T.; the fuel consumption Figure 2 is a rear plan view showing the posi in gallons per hour will be noted as F. C.; and the tion of the linkages when the R. P. M. indicator Output to the in horsepower will be is set at its maximum value, and the other indi abbreviated as H. P. cators remain at minimum value positions, the It will be observed that the device need not linkage comprising lever 74 and links 7, 76, and allow for all factors affecting engine performance, 96 being shown displaced slightly to the left to but should include those under the control of the more clearly show underlying parts; pilot having the most important effects on eff Figure 3 is a rear plan view showing linkage ciency. positions for maximum M. P. values, the others The primary object of the invention is to enable remaining at minimum value positions; 2 w 2,394,180 Figure 4 is a rear plan view showing the link was determined from such a study to be satis ages with the R. P. M., M.P., A., and T. indicators factorily expressed as: set at maximum values; and 2550-R. P. M. Figure 5 is a front perspective view of my de vice mounted in its case. r 1+.5(EE ) In order to make clear the theoretical consid after which formula (2) becomes erations upon which the design of a device em bodying the present invention must be based, the a H. P-1+.5 2550-R.900 P. M))x way in which the set values of R. P. M., M. P., A., .1966 (R.P.M. - 1650) (2 and T. are combined to indicate H. P., F. C., and () B. M. E. P. will be considered, first evaluating Consider next the effect of increasing the M. P., the influence of each on the H. P. Under Stand other factors being held as at the beginning of the ard conditions of temperature and pressure at test for R. P. M. change: increasing the M. P. sea level; that is, 59 F., and 29.92 in. Hg, at 0 ft. from 24 to 37 in. Hg while holding the R. P. M. elevation, horsepower is given by the known 5 at 1650 increases the output from 343 H.P. to 680 theoretical equation: H. P., a change of 337 H. P. Thus the average B. M.E.P.x DX R.P.M. rate of increase is H.P. = 33000X2 (1) 680-343 337 H.P. per unit M.P. Where 37 - 24 or 13 B. M. E. F. = average cylinder pressure through 20 increase within the range of 24 to 37 in. Hg, or out the firing stroke. H.P. increase is equal to D=total displacement of all of the , and 337 iXincrease in M.P. t; M =number of firing strokes per minute in An extrapolation formula whereby the horse a four-cycle engine. power developed at any manifold pressure above Since the displacement is fixed by the engine or below 24 in. Hg may be determined may there design, it is obvious that the H. P. theoretically fore be stated as: varies with the B. M. E. P. and the R. P. M. 30 B. H. P.=25.92 (M.P.-24) (4) Many other factors, however, influence the where "B H. P.' is the positive or negative change actual power output; for example, friction, scav in horsepower from the basic value of 343 H. P. enging, timing, M. P., fuel-air ratio, and combus effected by altering manifold pressure alone. tion efficiency. It has not been found possible It is found by actual test, however, that if the to combine these factors in a general equation of M. P. is held at 37 in. Hg, and the speed again useful form, so it has been necessary to rely on raised to 2550 R. P. M., a further increase in test data, and to vary the specific dimensions of power occurs to 915 H. P., a change of 235 H. P., the parts of the instrument in accordance with . which is 235-177, or 58 H. P. more than the the data obtained from tests with each different addition produced by the same speed increase type of engine. From this data, empirical equa 40 tions are derived for power change in terms of at the lower value of M. P. Hence an additional each of the variables under the pilot's control, factor must be added to show correctly the H. P. and these equations determine the design of the change when both R. P. M. and M. P. are varied. computing mechanism. This combination factor, following the same pro As an example, test figures will be given for a cedure as used in deriving Equations 3 and 4 particular engine of 1830 cu. in. displacement 45 above, can be Written as developing 343 actual H. P. at 1650 R. P. M. and 235-177 XR. P.M. increaseX M. P. 24 in. Hg M. P. under standard conditions of (37-24) (2550-1650) altitude and temperature. The effect of speed increase. An extrapolation formula whereby the changes on the power output was first deter 50 difference between the change in H. P. effected mined. It was found, by test, that the output by altering M. P. or R. P. M. alone and the was raised to 520 H. P. by increasing the speed change in H. P. effected by concurrent alteration to 2550 R. P. M., a change of 177 H. P. Thus the of M. P. and R. P. M. may be determined, may average rate of increase was therefore be stated as: 520 - 343 177 2550-1650 900 H.P. per unit R.P.M. 55 y H. P.s.l.00496 (R. P. M.-1650) (M.P.-24) (5) where "y H. P.' is the positive or negative change increase within the range of 1650 to 2550, and the in H. P. from the basic value of 343 H. P. effected increase in H.P. is by concurrent alteration of manifold pressure. 177 and Speed. 900X increase of R.P.M 60 The total H. P. change due to variations in An extrapolation formula whereby the horse speed and manifold pressure is the sum of Equa power developed at any speed above or below 1650 tions 3, 4, and 5, and when algebraically added to R. P. M. may be determined may therefore be the original base power output, gives, for any Stated as: w M. P. and R. P. M. within the operating range: cy H. P. s.1966 (R. P.M.-650) (2) H. P-343+1+5(250250 P.M.P.M.) X where “a H. P.' is the positive or negative change in horsepower from the basic value of 343 H. P. .1966 (R.P.M.-1650)-(-25.92 (M.P.-24)-- effected by altering speed alone. O .00496 (R.P.M. - 1650) (M.P.-24) (6) A study of the power curves shows, however, Changes in altitude have various and conflict that the increase of H. P. per unit increase of ing effects on horsepower developed by an internal R. P. M. decreases towards the higher values of combustion engine. By standard thermodynamic R. P. M. and So Equation 2 must be modified by equations, the power is proportional to the differ inserting an empirical multiplying factor which 75 ence between the carburetor and exhaust tem

2,894,180 3 peratures in degrees absolute during the firing ment in the last factor: to-wit, the temperature stroke. At higher altitudes, the back exhaust correction of Equation 8, is properly cared for pressure is reduced, and consequently the ex in the device, as will be seen from the following haust temperature; so a greater proportion of the description, by making this correction from a energy in the heat cycle is available, and the multiplying factor on the H. P. value as totaled power is increased. from the other factors. To offset this effect, the reduced density of air The details of the mechanism will now be re at higher altitudes means a smaller supply of ferred to in order that the mechanical arrange oxygen and less complete combustion; while the ment which is necessary to effect solution of reduced temperature of the entering air means O Equation 9 may be understood. a lower maximum temperature during the firing In Figure 5 there is shown the device f enclosed cycle, in a case 2. The case may be formed of steel or These power-reducing tendencies are again op of any strong, light material, pressed or other posed by the greater density per unit volume of wise, shaped into a shallow rectangular box, Open air at reduced temperatures, and by the use of a 5 at the front. A closure rim 4 is fastened by screws at higher altitudes which supplies 5 to the case 2 about its open face, and is arranged air in volume sufficient for COmbustion at normal to hold in position a face plate 6 which nests eficiency. \ . snugly into the case 2 and supports the working The sum of these influences acting to increase parts. The plate may be engaged by the same and decrease the power is practically, as shown screws 5 which secure the rim 4. Plate 6 is pref by the tests mentioned above, dependent on the erably made of a strong but easily worked, non altitude alone. tarnishing, light material. The effect of altitude at any value of M.P. and Four pointer-type knobs, Ta, 9, 10, and l are R. P. M. was found from tests to be capable of removably mounted on shafts 7, 9, 0, and representation by the equation respectively, journaled in a horizontal row on the face plate 6 near the bottom thereof. These AHP-R(too)(2.1-soo)A. A. knobs indicate R. P. M., M. P., A., and T., respec where R is the increase of H. P. from sea level tively, an? are set by the operator in accordance to 5000 feet. For the tested engine, R was 50 with his instrument readings, over scales 2, 4, 30 ls, and 6, respectively. In the particular case H. P. Hence, - outlined above, the graduations of scale 2 would A. A. preferably be from 1500 to 2700 R. P. M.; of scale AH.P.-50(too)(2.1 T50,000 (7) 4, from 20 to 45 inches of mercury; scale 5, from It was found that this increase was practically 0 to 25,000 feet altitude; and of scale, 6,.. from independent of M. P., R. P. M., and H. P., where 35 -60 to --140' F. Obviously, the specific gradua standard altitude conditions were maintained, the tions may vary for different engines, however, error due to neglect of these factors being less and so they have not been applied to the figure. than one per cent, and the tests extending from In the upper portion of the plate 6 are symmet 0 to 25,000 feet elevation. rically disposed two scale-bearing windows 2 and A comparable test of the effect of carburetor 40 22, on which may be read brake horsepower and temperature changes showed that it could be fuel consumption, respectively, in accordance represented by a constant times the deviation with the positions of their respective pointers from standard temperature for any given alt and 9, which are supported, in a manner to be tude, times the power. Since the constant was described later, from the rear of plate 6. A the same for all engines tested, this becomes, 45 pointer 20 is also mounted on the rear of plate 6, where T is the deviation from standard temper and indicates brake mean effective pressure by ature for the given altitude: its position behind a scale-bearing window 28, e H. P.-00105XT.dxH. P. (8) formed centrally of the plate 6. The graduations on window 2 preferably would range in the where e H. P. is the positive or negative change above case from 100 to 1400 H. P., those on win in H. P. effected by deviation of carburetor tem 50 dow 22 would show a fuel consumption range perature from standard temperature for a given from 15 to 160 gallons of gasoline per hour, and altitude. those on window 23 would indicate B. M. E. P. For this particular engine, the H. P. for any values from 100 to 200 pounds per square inch value of R. P. M., M. P., A., and T., is, within the cylinder pressure, with a zone 24 marked to show tested ranges, the algebraic sum of Equations 6, the optimum range for the particular engine. 7, and 8, or: Obviously, these ranges may change with differ Total H. P.-343+ ent engines. (fron 3) Referring now to Figure 1, the device is shown from the rear of plate 6, with the case 2 removed. 1+.5(20EM)x.1966(R.P.M.–1650)+ - A horizontal supporting strip 25 is mounted on, (from 4) but separated slightly from the plate 6 by suit 25.92 (M.P.-24) -- able spacers, not shown. This strip 25 is in posi (from 5) - tion to act as a second bearing support for those .00496 (R.P.M. - 1650) (M.P.-24) -- portions of shafts 7, 9, 0, and which extend (from 7) through plate 6 and the strip 25, and to which A A are fixed pinions 26, 27, 29, and 30, respectively. Each pinion is held in engagement with a cor (from 8) 50(too)(1-soo)+ responding rack 3, 32, 34, and 35, the racks .00105XTdxH.P. (9) O being urged against the pinions by resilient angle It has been found that in use the relations of pieces 36, 37, 39, and 40 secured to the supporting Equation 9 may be extrapolated beyond the limits strip 25. of the basic tests with good accuracy. The method Blocks 4, 42, 44, and 45 fixed to the bottom of of extending the scale calibrations will be ex the racks. , 32, 34, and 35, respectively, act as plained hereafter. The presence of the H. P. ele S bases for the attachment of connecting rods, 4. 2,394,180 formed preferably of an easily Worked resilient pin 62. Link 7 leads to the other racks by link material such as brass, which carry he move ages to be described subsequently, and its posi ment of the respective knobs to the linkages con tion may be considered as fixed for the purpose trolling the pointers 7, 9, and 20. To either of the present portion of the description. There or both ends of these connecting rods, and to fore, when rod 60 is drawn downward, the pivot those to be described below, there is attached a is is displaced downward, carrying with it lever yoke fitting 20 which is arranged for pivotal 6. Lever 66 carries a pivot 45 connecting connection to an aSSociated member and for ad through a rod 46 and pivot 47 to a lever 49, justment to control the length of the connecting fixed in turn to a shaft 5 rotatably mounted rod from block to pivot. This arrangement is O in a bearing block 50. Shaft 5i carries the wholly convention; for example, a threaded rod H. P. pointer 7, which is seen from the front of Cooperating with an internally threaded fitting, plate 6 through the window 2, and is moved and has not been illustrated in detail. Any type through the described linkages in proportion to of adjustable connection permitting removal of the rotation of the R. P. M. knob 7, in accord any individual rod. Without disturbing others is 5 ance With Equation 3. Window 2, and the cor fully equivalent. The setting knobs, he shafts responding windows 22 and 23 seen in Figure 5, On Which they are mounted, their respective have been omitted from the showing in Figures pinions, racks and blocks 4, 42, 44 and 45 are l to 4 to avoid confusion. A tension spring 53, Considered as the respective setting means or the attached to a stud 5 on plate 6, urges connect settable factor entering means by which various 20 ing rod f46, and through it the H. P. pointer 7, Waiues are entered. toward its minimum value position. The linkages by means of which the effect of The next sequence of linkages to be described R. P. M. change is carried from rack 3 to is that by which the effect of M. P. changes is pointer fi in accordance with Equation 3 will be introduced. By Equation 4, the H. P. change described next, reference being had to Figure 2 25 bears a linear relation to M. P. changes, and so which shows the positions for the maximum the vertical displacement of rack 32 must be R. P. M. on the above described scale. proportional to that imparted to the connecting Movement of rack 3 must produce a displace rod f which directly controls movement of the ment of the pointer proportional to 1966 H. P. pointer . The positions of the linkages (R. P.M.-1650) multiplied by 30 are shown in Figure 3 for maximum M. P. values On the scales described. A 84 is fixed to rack 32, and is 1+ (550 SPM) pivotally linked by pin 82 to a horizontal lever Entry of the first of these factors requires only 9. The opposite end of lever 79 bears a pin 80 that the movement of pointer f7 be directly pro 35 joined to a connecting rod 8, in turn attached portional to the movement of rack 3, and such a to the A. rack 34. When only the M. P. setting factor can be entered by conventional linkages is changed, pin 80 acts as a fixed pivot for lever designed to tranSnit movement of the rack to 9, and when rack 32 is drawn down, lever 79 the pointer in the proportion indicated by the pulls down also a vertical link 76 attached there factor. Entry of the second factor, however, re 40 to by a pin TT. quires that the rate of movement of pointer The upper end of link 6 is connected by a pin by rack 3 decrease as the rack is lowered. 5 to yet another horizontal lever 74, at the op Such movement of pointer by rack 3 is ac posite end of which is a pin 95 which may be complished by pivotally connecting a rod 52, at regarded as a fixed pivot for lever 74 for the tached to rack 3, to a specially shaped lever 54 45 purpose of the present portion of the descrip pivotally mounted at 58 and pivotally connected tion. intermediate its ends at 6 to a rod 60 where With pin 95 in fixed position, lever T4 rocks by the resultant movement is transmitted to thereabout when link 76 is drawn down, and ani pointer 7. other vertical link , attached thereto by a pin As the pivotal connection 53 between rod 52 2, is vertically displaced. It was said above that and lever 54 is lowered, lever 54 is rocked coun link was pivoted to horizontal lever 64 by a terclockwise about its pivot 58 (which may be pin 0; therefore, when link 7 is pulled down, regarded as a fixed pivot for the purpose of the lever 64 must pivot on its bearing 65 and the present portion of the description), and pivot 6 Opposite end pin 62, which may be regarded as is lowered. The ever 54 is curved to place the 55 a fixed pivot for the purpose of the present por pivot 6 initially closer to a position vertically tion of the description; so bearing 65 in lever 66 below pivot 58 and thus cause the rate at which must be vertically displaced when link T is drawn pivot 6 is lowered to decrease as sharply as is down. This causes lever 66 to pivot about its required by the Second factor of the formula fixed bearing support 6 in block 69, and moves under consideration. The curvature of lever 54 the H. P. pointer just as above described in con may of course be made greater or smaller to con nection with R. P. M. change. form to formulae derived from the test data on The effect of increasing both M. P. and R. P. various engines for which specific instruments M., as set forth in Equation 5, is transmitted by may be designed. the scissor linkages or multiplying mechanism The linkage which transmits the vertical dis which will next be described, and which may be placement of rod 60 to pointer comprises lever understood by referring to Figures 1 and 4. 4 pivotally connected to rod 6 by pin 62 through In brief, the Scissor linkages or multiplying , adjustable fitting 20. Lever 64 is in turn piv mechanism operate by lowering the fixed pivot otally connected at 65 to a lever 6, the latter 5, and hence increasing the vertical displace being rockable about a fixed pivot 67 in a block 70 ment of Connecting rod 60 which will be effected 69 attached to the plate 6. by a given displacement of connecting rod 52. When rod 60 pulls down on lever 64, the latter The linkages consist of three horizontal levers is forced to pivot not only about its pivotal con 49, , and 86, of equal length. Lever 49 is car nection 65, but also about a pin. To by which lever ried by a bearing 50 pivotally mounted in a fixed 64 is attached to a link 7 at the end opposite s Supporting block 5 attached to the plate 6. At 2,894,180 5 its opposite end, a pin 48 ties lever 49 to lever The H. P. factor is taken from lever 66 by a 4 and to a second connecting rod 46 attached vertical link 2 connected thereto by a pin to the R. P. M. rack 3. Lever 47, at its end op f. A pin 07 joins link 2 to one end of posite pin 48, is pivotally connected by a pin 88 scissor links 09 and 06 of equal length. The to lever 86 and to a link 85 pivotally joined to opposite end of link 09 which may be considered the horizontal lever 9 at the point of attach as a guide element is supported pivotally by a ment 82 of the connecting rod 84 leading to the bearing fle in fixed pivot block ff. The op M. P. rack 32. Pin 88 is coaxial with bearing 50 posite end of link 06 is pivotally connected by when the M. P. value is at the test value of 24 in. pin 05 to the third scissor link 104 of the same Hg, as shown in Figure 1; but such coaxiality 10 length, and to a vertical link 86 joined by a pivot might occur at any scale value depending upon pin 87 to a horizontal lever 82. A second con the scale range selected and the characteristics necting rod 180 is attached to the rack 34, and of the motor on which the instrument design is connected by a pin 18 to horizontal lever 82. based. It will occur in any case at the scale val At its opposite end, lever 82 is pivotally attached ues of M. P. and R. P. M., which will make the 5 by pin 184. to the connecting rod 85 pivotally result of Equation 5 equal to zero. secured to the T. rack 35. The position of pin At its end opposite pin 88, lever 86 is connected 87 is such that no vertical displacement occurs by a pin 87 to the lower arm 89 of bell crank for any value of A, providing the T. value is 59. As bell crank 59 is turned about its fixed standard. If the T. value is standard in relation pivot 90 in supporting block 9, vertical link 5.5 20 to A, the pivots 05 and ?o will be coaxial and is displaced. the displacement of pivot O will not change the Drawing down only the R. P. M. rack 31, as position of the bell crank OO. shown in Figure 2, causes no change in the ver If the temperature is not at standard value, tical position of link 5.5, when the pivot 50 of the linkage positions may be as shown in Figure 4, lever 49 and the pivot 88 of lever 47 are coaxial for example. Here the altitude is set at maxi as shown in said figure. Likewise, drawing down num, and likewise the temperature. Actually, only the M. P. rack 32 causes no change in the standard temperature for 25000 elevation is vertical position of link 5.5 when the pivot 48 of -30 F., and so a negative correction for the levers 47 and 49 and the pivot 87 of lever 86 on difference between -30 F. and --140 F. must be arm 89 of bell crank 59 are coaxial. This spe made. Link 86 has been drawn down, causing cific position is not shown in the drawings, how scissor link 06 to pivot about 07, which is fixed ever, because the scale of the R. P. M. pointer by the total H. P. value, thus forcing link 94 to has been extended to 1500 R. P. M. by extra rock bell crank 00 counter-clockwise, raising polation which is below the test value of 1650 link 7 and reducing the indicated H. P. by forc R. P. M., and the rack 3 is shown only in its ing lever 66 to pivot about 67. minimum and maximum scale value positions. If we move the R. P. M. pinion 26 from the When both R. P. M. and M. P. racks are drawn position shown in Figure 1 to that shown in down, as in Figure 4, link 85 forces pivot 88 away Figure 2, the parts 52, 53, left-hand end of lever from its position coaxial with bearing 50, and 54, rod 60, pin 62, right-hand end of ever 64, draws down also the associated end of lever 86 pin 65, and the right-hand end of lever 66 are rockirig lever 47 about pivot 48. Since the posi also lowered to increase the reading on the H. P. tions of pivots 50, 48, and 88 are held by their pointer . However, as the right-hand end of associated linkages, the lever 86 must rock bell the lever 66 is lowered, its left-hand end f4 is crank 59 clockwise to accommodate the vertical raised, thereby elevating link 2, pin 07 and displacement of pivot 88. Wertical link 5.5 is dis the left-hand end of links 106 and O9, thereby placed downwardly, and the combination effect increasing the distance between pins 07 and O2. of M. P. and R. P. M. is then carried to the point If the pin 07 is raised, it moves in an arc of a er 7 through rod 60 and the linkage previously circle around the point O so that link 06 is described. pushed to the right, thereby rotating the lever Altitude correction, in accordance with Equa 50 100 clockwise through link 104. This clockwise tion 7, is proportional to the altitude, and is in rotation of lever 100 lowers the parts 97, 96, 95, serted through rack 34 (Figure 1) and Connect 72, 7, 70 and 65, thereby further lowering the ing rod 8, which acts to control movement of right-hand end of lever 66. It will, therefore, be horizontal lever 79, through pin 80, about pin 82 noted that the regenerative mechanism feeds as a fixed pivot, and to displace link 76 vertically. 55 back an additional movement which is additive The sequence thereafter is identical with that for to what would have been the movement of the M. P. change in the Way it reaches the H. P. right-hand end of the lever 66 if there had been pointer. no regenerative mechanism. Temperature correction, by Equation 8, is pro If the parts are in the position shown in portional to the H. P. and to the deviation of the Figure 1, and we rotate pinion 30 so as to lower carburetor temperature from standard tempera 85, 84, 87, 186 and 05, the link 04 is moved ture for the given altitude. It is introduced by to the left rotating lever 100 anti-clockwise and setting a bell crank 00 which is controlled by raising 9, 96, 95, T2, 7, 7 and 65, thereby rais connection both to the H. P. as totaled by the ing the right-hand end of lever 66 and lowering other variables, and to the temperature and alti 65 4, f2 and 107, which gives an additional move tude racks 35 and 34 respectively, which are con ment to the left of the link 104, thereby feeding nected together in such a way as to give the back an additional additive, movement to the deviation of the carburetor temperature from right-hand end of lever 66. Of course, if we standard altitude temperature. These two fac simultaneously rotated pinions 26 and 3D so as tors, H. P. and T, are combined by a scissors 70 linkage which directly controls the position of to lower racks 3 and 35, the movement of rack bell crank 00, which in turn sets the correction would tend to lower the right-hand end of into the H. P. indicator through connecting rod lever 66 and increase the H. P. reading, while 96 pivotally connected thereto at 97 and to lever the movement of rack 5 would tend to raise the at , 75 right-hand end of lever so that the resultant 6 2,894,180 movement of the H.P. indicator T would be the values of 20 for M.P., zero altitude, and standard difference between these movements. temperature. Actually the scale maximum is car The regenerative mechanism, however, is not ried to 140 F., and by Equation 8, the correction necessarily additive. For instance, suppose the for the range between T. and standard temper parts are in the position shown in Figure s ature, --59F, is: suppose pinion 29 is rotated to lower rac - - E. 80 and 8. Rod 8, as it moves down- e H. P-00105(150 59) (195.5) wardly, lowers parts 80, left-hand end of lever which in view of the fact that the temperature i.e., 16, 15, right-hand end of lever 14, link. correction is fed in regeneratively, the movement left-hand part of lever 64, pin , thereby 10 of lever B by connecting rod 96 effecting fur lowering right-hand end of lever 66, thereby ther movement of the temperature correction tending to increase the reis, the . linkages through link 2, should be stated: inter T. However, the lowering of rod E. the right-hand end of lever 82, pin , e H. P.-00105 (91) (195.5--e H. P.) link 86 and pin iOS, thereby through ink 1. As a mathematical equation this is capable of locking lever OO anti-clockwise and raising 9 solution only by successive integrations, but it 6, 95, left-hand end of lever T4, T , left-hand end of lever 64 and pin 65, thereby raising the . E, E,it. right-hand end of lever 66, thereby tending to equation is solved simultaneously by the regen decrease the reading of the H. P. pointer . In 20 this case the regenerative mechanisms act Sub- Eyechanism described. The approximate tractively. The mechanism, therefore, whereby the initial e H. P.s 16.9 movement of one part is fed back through S mechanism so as to vary the movement of the said 25 d this gives part over that initially imparted to it is called Base H. P.-195.5-16.9-178.6 (10) a regenerative mechanism, this term being Sug gested by the well-known feed back or regenera- To find next the maximum value, by Equation 6: tive electric circuit in a feedback amplifier. 2550-2700 Consideration of the additional linkages re- 80 H.P.-343+1+ s(5,70 ) X quired to actuate the B. M. E. P. and F. C. point ers will be deferred until the method of design ing the proper linkage and lever lengths, and the .1966 (2700- 1650)}+25.92(45–24)+ calibration of the R. P. M. M. P., A., and T. .00496 (2700-1650)(45-24) scales is explained. which reduces to: It is obvious that the full range of H. P., an CeSO R. P. M., values possible need not be provided H.P. = 343-- (.9167)x206.4} - 544.3+(109.4 for on the scales, for example; since in normal H.P. = 1185.9 operation the speed and power never drop to A 8 zero. The R. P. M. scale need extend, in the case 40 Correcting for altitude by Equation 7 at 25,000 of the instrument here described, as an example, feet: only from 1500 to 2700. Similarly, the pointers willthe testusually ranges, be indicatingso it is preferred readings to intermediateassume Ver- AH.P. =50(S10,000 (2.1-250,000 tical pointer positions for H. P., F. C., and B. M. =50X2.5X1.6 E.P., near the most common values, and arrange AH. P.=200, which gives . the mechanism to subtract from or add to the H. P. =1185.9-200=1385.9 values indicated in accordance with the R. P. M., M.P., A., and T. Settings. Correcting for temperature by Equation 8, In design, first we must find the effect of each 50 standard temperature being -30 F. at 25,000 of the variables, as determined from Equations feet, and the scale minimum being -60 F., we 6, 7, and 8, over the full range for which calibra- have tion of scales 2, 4, 5, and 6 is desired, in terms - of H. P. variation from the base value of power e H. P.E.00105-60- (-30) ) (1385.9) for standard altitude temperature at sea level, 55 which in view of the fact that the correction is fed which in the present example has been taken as in regeneratively should be stated: 343 H. P. From Equation 6: e H.P.-00105(-30) (1385.9--e H. P.) H.P. = 343-1 --. s(2559,509)x so giving an approximate mathematical solution: e H.P.-45.0 .1966 (1500- 1650+25.92(20-24) -- (.00496(1500-1650) (20-24)} H. P.-1389.9-45=1430.9 which reduces to: 6S which gives H.P. -m .584 - 0. Thus the total range of power over the full 343 - 1.5 92(4)s 5. .0049600496 (-150)(4)per Scale1786 rangeto the of maximum variables isof from1430.9 the H.P. base valueof this of giving a base value of H. P. =195.5, with base range, the components, as derived above, are:

Factor R. P. M. M. P. R. P.M. and M. P. A. T.

Range of Scales.------1,500 to 2,700.- 20 to 45-...------1,500 to 2,700 and 20 to 45.0 to 25,000--- (+1 H. P. deviation values at scale limits 68 to 89.2 - 103.7 to 544.3.3.0 to 109.4------0 to 200------St:3, 3. H. P. deviation total.------236.0------648.0------106-4------200------61.9.

2,894,180 7 The next step is to proportion the linkages to connection to a part of the linkage system mov give these changes on the H. P. dial for full scale ing proportionately with R. P. M., and to another settings of each variable. Consider the M. P. part moving with H. P. Connetting rod 9 (Fig and A. rack movements: the full vertical dis ure 1) is fixed to R. P. M. rack 3 f through block placement of M.P. rack 32, should cause a change 4, and is attached by a pin at its upper end of 648 H. P. in the position of pointer f7, while to a horizontal lever 6, the opposite end of the A. rack 34 must act to change pointer 7 by which is connected by a pivot 5 to vertical link 200 H. P. Lever 9 must contribute a motion to 2. the pointer T equivalent to 648-1-200, or 848 For R. P. M. rack movements, pivot 5 acts as H.P., when racks 32 and 34 are in maximum posi O a fixed center, and a movement proportional to tion. To find the proper position of pivot TT with that of the rack 3 is carried by a vertical link relation to pivots 80 and 82, the length of link 79 22, pivotally connected to lever 6 by a pin f2, being known, a proportion is set up between the and to a lever 4 by a pin 40. Lever 4 is ratio of the length of link 79 to the H. P. change supported nearly parallel to lever 66 by the link 5 22 and a pivot 42 at the opposite end, which accounted for by full deflection thereof, and the connects with an extension 44 from the lever 66. ratio of the distance from pivot 80 to pivot TT to This connection, together with the connection the H. P. change due to M. P. change, which is comprising link 2 and pivot 5 supplies the also equal to the ratio of the distance between movement proportional to H. P. Lever 4 is pivot 82 and pivot TT to the H. P. change due to pivotally connected to a connecting rod f 56 by a A. change. 20 pin 55, and rod 56 is pivotally attached at its Full deflection of the rack 35 produces, through lower end by a pin 57 to the upper arm f S9 of the scissor linkage associated with bell crank 00, a bell crank 60, rockably supported at 6f in a a vertical displacement of rod 96 and pivot 95, • fixed block 62 fixed to plate 6. The lower bell which represents 26i.2 H.P. change. crank arm 64 is pivotally attached by pin 65 Thus full displacement of racks 32, 34, and 35 to a connecting rod 66 pivotally connected at moves link a distance representing 70 to a lever T. Lever 7 is fixedly attached 261.2-648-909.2 H. P. to a shaft T2 journaled in a bearing block T4 fixed on plate 6. F. C. pointer f9 is fixed to the The H. P. variation range for movement of link shaft 72. Thus, the F. C. pointer is moved in 7 is now 626--848=1474 H. P. 30 accordance with the Equation 11 above. The On rack 3, the full deflection is modified by the relative proportions of the levers may be calcu M. P. Scissors acting through bell crank 59, and lated in a manner similar to that shown above in by the differential lever 54. Link 5.5 has a vertical computing the H. P. leverages, reducing the verti deflection for full scale M. P. change, which adds 35 cal travel of points 42, 7, and f 5 to equivalent 106.4 H. P. to the effect of R. P. M. effects in terms of F. C. variation. In deriving Equation 9, it was found that the B. M. E. P. is most conveniently indicated in multiplying factor required to bring the average variations from the optimum point, since it is figures for increase of H. P. with R. P. M. into desired to operate the engine at, or just slightly agreement with test curves was 1.584 at the lowest 40 below, a certain value. This range is indicated R. P. M. value, decreasing to 1-.0833, or .917 at on scale 23 by the zone 24. Rewriting Equation 1, maximum R. P. M. Lever 54 is designed so that the rate of vertical movement of connecting rod R.P.M.H.P. (12) 60 in proportion to that of pivot 53 is 45 where K is a constant for any given engine. 584 The pointer 20 is hence connected to a lever 917 joined at opposite ends to parts of the linkage or 1.73 times as great at the lower end of the moving in one direction for increase of H. P., and in the opposite direction for increase of R. P. M., R. P. M. Scale as at the upper, tapering off grad adjusting the lever lengths to hold pointer 20 in ually in between to solve the factor a certain position for constant B. M. E. P. values. Lever 6 is displaced downward at pivot for 1 -H.s(550, P.M.) R. P. M. increase, and upward at 5 for H. P. increase. Reducing the vertical movement of The full scale movement of rod 52 was equal to point 5 to equivalence with that of point 7, 236.0 H. P., and hence the rod 60 adds the effects of H. P. and R. P. M. in terms of 236.0+216–452 H.P. B. M. E. P. may be equated to obtain the lever Now it will be seen that the vertical displace lengths (if 5-2) and 2-7) in the specific ment of pivot 65 is proportional to the combined engine under consideration. 60 A connecting rod f 24 is attached to the lever H. P. variations, and it is a simple matter to relate S by pin 2, and at the upper. end of the rod the lengths (67-65) and (67-145) of lever 66 so a pin 25 supplies connection to the horizontal that pointer T will have the proper travel over arm 26 of a bell crank 27 rockably pivoted at the full H. P. range. 29 on a fixed block 30 attached to plate 6. Returning now to the linkages controlling the Lower, arm 3 of crank f2 is attached by a . F. C. and B.M. E. P. pointers, consider first the pin 32 to a horizontal connecting rod 34, pinned equation governing the former. The rate of con at 38 to the B. M. E. P. pointer 20, which is piv sumption varies with horsepower delivered and otally supported at 36 by a block 37 fixed to , R. P. M., and test results can be accurately ap plate 6. The comparative lengths of bell crank proximated by following the equation O 27, arms 126 and 3 can easily be proportioned F. C.-a(R. P. M.) --b(H.P.) -C (11) to produce the desired movement of pointer 20 Where for given B. M. E. P. changes. a=00775, b=-0624, and C=7.6 Attention is next directed to Figure 2 of the drawings, in which the respective linkage posi forHence this engine.the F. C. pointer must be actuated by tions are shown for maximum R. P. M., with all S 2,894,180 of the remaining values remaining at the mini It will be apparent that the positions of the mum. The position of bell crank 59 is unchanged, fixed pivots and indicating pointers may be since the scissor links 47 and 49 are of equal changed at will, and that linkage arrangements length anu hence link 86 is unaffected by move may be designed in accord with the same prin ment of rack 3. Pointers 7 and 9 are indi 5 ciples to filt any such variation. Any materials cating increased power and fuel consumption but may be used having the requisite characteristics pointer 20 indicates operation below the best eff of strength, resilience, and workability. ciency and B. M. E. P. value. It will be noticed In summary, the invention provides means for that the temperature correction through bell mechanically computing simultaneously the crank OO is increased slightly, although the posi 0. B. M. E. P., H. P., and F. C., of an internal tion of the temperature rack 35 is unchanged. combustion engine, by setting in observed values This follows from Equation 8, since the change is of R. P. M., M. P., A., and T. The design will proportional, not only to the deviation from differ for engines having different characteristics, standard temperature, but also to the total H. P. and is based on empirical equations derived from developed. 5 test data, since simple, theoretical equations can In Figure 3, the effect is shown of increasing not be used to cover all the factors affecting per the M. P. to maximum, holding R. P. M., A., and formance. The computed values are obtained T. at their minima. Power and fuel consumption by mechanically adding the effects on each of are increased over the showing in Figure 2, sub these values of the inserted variables. stantially, and the operation is more eficient, as 20 While the invention has been described with shown by the position of pointers 7, 9, and 20. particular reference to airplane engines, it will A temperature correction is added through the be obvious that it could be applied to any type bell crank f OO by the scissors links f4, 106, and of engine for which performance tests were avail 09, for the same reason as given above in the able, and to engines used in any type of service. case of R. P. M. increase. The increase in H. P. All such uses and modifications are deemed to is transmitted to pointer through lever and be within the scope of the appended claims. links 79, T6, 74, Ti, 64, and 66 from the rod 84 I claim: connected to rack 32. At the same time, scissor 1. In a computer of the type described, a plu action between links 47, 49, and 86, through link rality of differentially settable elements by means 85, rotates bell crank 59 and elevates pivot 56. 30 "Of which values may be entered, a first movable Link 5.5 rotates about pivot 56, causing crank 54 indicating device, connecting mechanism between to rock on pin 53 as a center, raising rod 60 to Said elements and said device for moving said effect the combination M. P.-R. P. M. correction device, a second movable indicating device, and of Ecuation 5. connecting mechanism between a part of the first In Figure 4 racks 3, 32, 34, and 35 are all in connecting mechanism, and said second device maximum position. The M. P. effect on H. P. for moving said second indicating device an is carried through the same sequence of levers as amount proportional to the differential move in Figure 3, and arm 57 of bell crank 59 is drawn ments of said first device and said part; a third down and the pivot 58 lowered to add in the movable indicating device, and connecting mech combination effect of R. P. M. and M. P. changes, 40 anism between one of the elements of the second while connecting rod 52 inserts the change due named connecting mechanism and said third de to R. P. M. alone in the same fashion as in vice for moving said third indicating device an Figure 2 through pivot 53. Scissor links 104, amount proportional to the difference of the dif 06, and 09 are adding a large temperature cor ferential movements of said first device and the rection, standard temperature being 170 F. less 45 said element of the second named connecting than the setting indicated. It should be noted mechanism. that the temperature rack functions by affecting 2. A motion transmitting linkage for calcu the position not only of links 04 and O. in lators comprising, a pivotally supported guide relation to bell crank 00, but also of links fos element, a first movable link having a pivotal and 09 in relation to the vertical position of 50 connection with said guide element radially link ff2, through the rotation of link 09 about Spaced from the pivotal support thereof, a second fixed pivot fo. movable link having a pivotal connection with It will be apparent that reliance is placed on said first link radially spaced from the pivotal the ability to bend the connecting rods in ac connection of said first link with said guide ele commodating the rack movements to those of the ment, a first movable member having a pivotal various levers. It will also be seen that the move connection with said second link radially spaced ments of some of the connecting rods and links from the pivotal connection between said links; is not in a straight vertical line, but rather along. all of Said radial Spacings being equal; a second arcs of circles. These arcs are relatively small, movable member having a pivotal connection however, so that the error in vertical displace 60 with said links coaxial with the aforesaid pivotal ment is Small. Compensation is also provided connection between them, a third movable mem by making the horizontal separation between ber connected to said guide element, an input pairs of pivots greater than that between their element connected to said third movable member corresponding Operating members. and means connecting the first movable member For example, the separation between pivots 80 to said input element whereby the movement of and 82 is greater than the center-to-center dis the input element is modified through said links, tance between racks 34 and 32. If rack 34 is said members and said guide element. drawn clear down while rack 32 is at minimum, 3. In a computer, setting means to introduce pivot 77 is drawn down in an arc about pivot values corresponding to engine speed and man 82, so that the vertical displacement of pivot TT 70 fold pressure, means actuated by the said setting would not equal that of rack 34. Since the con means to multiply a function of manifold pres necting rods are resilient, however, rod 84 will Sure by a function of engine speed, an addition bend to the left, restoring pivot 77 to its original lever, means connecting said lever and the engine vertical line of travel, and substantially correct speed setting means so as to move one end of said ing the error. 75 lever according to a function of engine speed, 2,894,180 9 means to actuate the other end of said lever by multiplied by a function of the second quantity, said multiplying mechanism, a link connected to a registering element, and means connecting said an intermediate portion of said addition lever, lever to said registering element. a second lever connected to one end of said link, 7. In a computer, a movable indicating device, means connecting the other end of said second factor entering means, operating connections in lever to the manifold pressure setting means, a cluding a lever interconnecting said device and horsepower indicator, and means, connecting an said factor entering means, a regenerative link intermediate portion of said second lever to said age, a connection from said lever for operating indicator. said linkage, and another connection between a 4. In a computer, setting means to introduce 10 fulcrum of said lever and said regenerative link values corresponding to engine speed, manifold age for effecting adjustment of the fulcrum of . pressure, altitude and temperature, a lever, means Said lever, said regenerative linkage including actuated by Said setting means to calculate horse adjustable means to vary the magnitude of the power and to actuate said lever. in accordance motion transmitted to the fulcrum of said lever, with the horsepower calculated, a horsepower 15 8. In a computer, a movable indicating device, indicator, means connecting said lever to said factor entering means, operating connections in indicator, a second lever, means connecting one cluding a lever interconnecting said device and end of said second lever to said first named lever said factor entering means, a regenerative link So as to actuate said end of said second ever an age, a connection from said lever for operating amount corresponding to a function of horse 20 said linkage, and another connection between a power, a third lever, means connecting the other fulcrum of said lever and said regenerative link end of said second lever to said third lever, means age for effecting adjustment of the fulcrum of whereby one end of the third lever is actuated by Said lever. the engine Speed setting means, means whereby 9. In a computer, an indicating device, actuat the other end of said third lever is actuated by ing mechanism therefor, a pair of factor entering said first named lever, a fuel consumption indi means, summation means operated by said factor cator, and means connecting said second lever to entering means and connected to an element of said fuel consumption indicator. said actuating mechanism for operating same, ". 5. In a computer, setting means to introduce regenerative means including three intercon values corresponding to a first quantity and a 30 nected links actuated by said element of said Second quantity, means actuated by the said Set actuating mechanism, and a connection from said ting means to multiply a function of said first regenerative means to said summation means for quantity by a function of said second quantity, imparting a supplementary movement to said an addition lever, means connecting said lever Summation means. and said first quantity setting means so as to 35 10. In a computer, an indicating device, actuat move one end of said lever acoording to a func ing mechanism therefor, a pair of factor entering tion of said first quantity, means to actuate the means, summation means operated by said factor other end of said lever by said multiplying means, entering means and connected to an element of a link connected to an intermediate portion of said actuating mechanism for operating same, said addition lever; said addition lever being so 40 regenerative means including three intercon shaped as to effect angular adjustment of said nected links actuated by said element of said link at a progressively varying rate as said addi actuating mechanism, a connection from said re tion lever is angularly adjusted by said setting generative means to said summation means for means, a Second lever connected to one end of said imparting a supplementary movement to said. link, means connecting the other end of said sec 5 summation means, and adjustable means in said Ond lever to said second quantity setting means, regenerative means to vary the rate of said Sup a registering element, and means connecting an plementary movement. intermediate portion of said second lever to said 11. In a computer, a movable indicating device, registering element. factor entering means, operating connections in 6. In a computer, setting means to introduce 50 termediate said entering means and said indicat values corresponding to a first quantity, a second ing device for operating the same, including a quantity and a third quantity, means to add a pivoted lever and a second lever pivoted on said function of the value set by the second quantity first lever, a regenerative linkage, means for op setting means to a function of the value set by the erating said linkage from said first lever, and con third quantity setting means, a lever, means to nections from said regenerative linkage to said actuate One end of said lever by the value of said second lever for transmitting a supplementary sum, means actuated by said second quantity set movement to both of said levers whereby a comi ting means and by said first quantity setting posite actuation of said indicating device is means to actuate the other end of said lever by effected. the sum of a function of the first quantity plus 60 WS W. M.V. the product of a function of the first quantity