Patent GB-905538-A (GB)
Title: Equipment for planning the loading of cargo aircraft
IPC: G06G7/70
Filed: 1958-08-12
Abstract: 905,538. Aircraft loading computers. CONTINENTAL ELECTROLOG CORPORATION. Aug. 12, 1958 [Aug. 20, 1957], No. 25899/58. Class 37. An aircraft loading computer comprises a number of decade resistors into which known weight and aircraft parameters can be set to determine the manner of distribution of unladen cargo in a number of compartments to obtain a final desirable centre of gravity or to determine the effect on the position of the C.G. of weights off-loaded, self-balancing bridges being provided to multiply loads by distances from a reference point (usually the nose of the aircraft) whereby moments may be computed; and a number of weight and moment accumulators being provided whereby planned loads and their moments respectively may be added to the aircraft weight &c. to show total load, the remaining capacity, and moment available if the desired C.G. is to be obtained. The equipment determines the portion of cargo weight to be loaded into the first of a number of compartments having a predetermined load distribution pattern so that after the portion is loaded the ratio SL of the then remaining-cargo moment to the remaining cargo weight is substantially equal to the ratio S#-F of the sum of the moments of the selected weight distribution pattern to the sum of the selected weights for such compartments, the condition being checked by a self-balancing bridge. The comparison shows whether the planned load will give the desired result, whether the first compartment may be further loaded, and if so whether the last compartment which has a great moment should be omitted from the planning to counteract the necessity of a proportionately great load in the first compartment which would result in bending of the aircraft frame, or whether the first compartment should be left unloaded. Short-circuiting arrangements are provided whereby compartments which it is found desirable to keep empty may be excluded from the computation. The equipment can also determine whether the load to be carried is greater than the plane's total capacity or whether the planned load for a compartment exceeds the compartment capacity. The parameters which may be set manually into the computer are the primary weight of the aircraft, the primary C.G. of the aircraft, the position of the desired C.G., the cargo weight, the planned weight to be loaded into the respective compartments, and a fixed position for each compartment ; and the following parameters may be determined :-the desired gross moment (desired C.G. position x sum of primary weight X cargo weight), the moment of the planned load for each compartment, the primary moment of the aircraft, the remaining moment (gross moment-sum of primary moment and preload and cargo moments thus far planned), the remaining weight, the accumulated or gross weight, the accumulated moment, and the centre of gravity position. To prepare equipment, reset switches 187, Fig. 6, of gross weight accumulator and programmer, 73W, 85W, gross moment accumulator and programmer, 73M, 85M, remaining weight accumulator and programmer, 75W<SP>1</SP>, 85W<SP>1</SP>, and remaining moment accumulator and programmer, 73M<SP>1</SP>, 85M<SP>1</SP> are closed to operate relays 126 to home their respective stepping switches 93-95. Relays 126 are then released. Type-of-aircraft switch 70, Fig. 4, is set to insert compartment centroid resistors RB1- RG1, Fig. 4, resistors RWB 1 -RWG 1  and RMB 1 -RMG 1 , Fig. 13, relating to the compartments for the particular aircraft and the weight of the aircraft is set in the weight register 21, Fig. 1, Fig. 2. Individual resistors R1, R10 and R100 in bank E representing 100, 1000 and 10,000 pounds respectively. Primary centroid i.e. distance in inches from a reference point is inserted in the H.T.U. resistors of arm register 41, described with respect to Fig. 3 (not shown). With the switch 48 in primary condition PC. A self-balancing bridge comprising resistor 35, Fig. 4, and 45, Fig. 4, of the above two registers, fixed resistor 72 and the bank F of multiplier A unit, Fig. 5. The bank F wipers are driven after operation of a manual start switch by multiplier A programmer 217 which responds to unbalance indicated by an output from phase-sensitive amplifier 80 to balance the bridge. The setting of bank F is then indicative of the primary moment, and programmer 217 then cycles to the next step of its operation. Add switches 154, Fig. 6, of similar units 85W, 73W, 85M, 73M, 85M<SP>1</SP>, 73M<SP>1</SP> are manually closed momentarily to transfer the gross weight and the gross moment from the registers to accumulators, the primary or gross moment being transferred to the gross moment accumulator 73M and the remaining moment accumulator 73M<SP>1</SP>. Typically, start button 137 operated by the programmer 217 operating stepping switches 91, 93-95 to effect the transfer, the accumulators 73M<SP>1</SP>, 73M being connected in parallel. The resistors inserted in the remaining moment accumulator are the complement of 9-9-9. Add switches 154 are opened and the position selector switch, Fig. 4, is now switched to D.C. (desired condition). Load, and desired moment are inserted in the weight register, and arm register respectively, the former introducing into the self-balancing bridge a resistance in series with the weight set in the gross weight accumulator to give the desired gross take-off weight and the moment is set up in bank F as before. Subtract switches are now closed and the weight from the register and the moment from its register are transferred to the remaining weight accumulator and the remaining moment accumulator respectively. The selector switch at " station load " enables the bridge to determine the moment of a weight to be added at a particular position, say in a particular compartment D, the weight and the position being injected in the weight and arm registers. The new conditions are set in the accumulators as before, the weight and moment being added in the gross accumulators and subtracted from the remaining accumulators. When considering the distribution of the remaining load the particular compartment D loaded above is excluded from the computation by closing switch 385D (Fig. 13) which shortcircuits the resistances RMD 1 , RWD 1 , corresponding to the moment and maximum weight of the compartment. Multiplier B, Fig. 9, compares:- EM - F sum of moments of compartments to be loaded less first/#W - F sum of weights of compartments to be loaded less first with RM (remaining moment)/RW (remaining weight) EM - F, #W - F values are supplied by the series resistors RMC 1 , RME 1 , RMF 1 , RMG 1 , and RWC 1 , KWE 1 , RWF 1 , RWG 1  and RM, RW by the series resistors set in the " remaining moment " and " remaining weight " accumulators. If EM - F/#W - F> RM/RW switch 251, Fig. 9, moves to position 2 to compare #M - L/ #W - L with RM/RW, where #M - L, #W - L are the moment and maximum weight of the compartments except the last. No output, i.e. M - F/W - F # RM/RW, lights " omit-thiscompartment " indicator which remains alight until the next compartment is selected by switch 48. When switch 251 is stepped to position 2 and #M - L/#W - L > RM/RW relay 431 is operated by a phase-sensitive amplifier 301 to light " remove-final-compartment " indicator. The compartment can be removed by switch 385G short-circuiting RWG 1 , RMG 1  and new #W - L, EM - L are set up. If new EM - L/ #W - L < RM/RW there is no output from the bridge and switch 251 is moved to position 3 by the multiplier 13 programmer after a predetermined time. In this position a check is made to see if the intended load is within the total capacity of the compartment or the remaining weight resistors and the compartment weight resistors being inserted in the bridge. If the remaining weight exceeds the capacity of the compartments the fact is indicated by a lamp 432 and a complete replanning as above is required. If the load can be accommodated switch 251 is switched to position 4 to determine the portion of the remaining load to be distributed into the first compartment B of the group, #R(#M - F/#W - F . RW - RM) and #B(#M - F/#W - F . WF - MF) being first determined. To obtain #R the bridge B2 is set up with the following arms: (1) the moment resistors RMC 1 , RME 1 , RMF 1 , for the compartments under consideration; (2) the weight resistors for the compartments; (3) the remaining moment resistor 203 of the RM accumulator, and multiplier B balancing resistors 314; and #R is given by value of resistors 314 at balance. The stepping switches which adjust resistors 314 set the wipers of a further bank B, Fig. 10, to corresponding positions. The programmer 313 then closes switch 343 and causes stepping switches 327, 328, 329, to set up #R on the resistor bank 330. #B, determined in a similar manner when switch 251 is advanced to position 5, is set up on a storage register, Fig. 11 (not shown) and the two #R, #B are subsequently compared in a bridge circuit including the two registers when switch 251 is moved to position 6. #R> #B indicates that the particular compartment may be loaded to its maximum capacity. Switch 251 is advanced to position 8 when #R> #B and indicator lamps are caused to indicate the maximum capacity by balancing the bank B contacts of the switches 307-309 controlling the adjustable resistors 314 which are balanced against the compartment weight resistor in the bridge B2. The new conditions, i.e. the computed weight and moment are set into the various accumulators to give new remaining weight and moment figures, gross weight and moment &c. When #B> #R the switch 251 is switched to position 7 and a proportion of the maximum load dependent on #R/ #B is shown by digital indicator lamps. The compartment switch is switched to the next compartment, and the procedure repeated for the remaining compartments, a last compartment lamp 423 being lit on the final step. The