US2926688A - Precise control distribution of airplane fuel stores - Google Patents

Description

March 1, 1960 R. A. MUMA EI'AL 2, 2

PRECISE CONTROL DISTRIBUTION OF AIRPLANE FUEL STORES 2 Sheets-Sheet 1 v Filed May 8, 1956 March 1, 1960 R. A. MUMA ETAL PRECISE CONTROL DISTRIBUTION OF AIRPLANE FUEL STORES Flled May 8, 1956 2 Sheets-Sheet 2 GT OENEY modified and 1 With n tt fi :t ue :intcnt and .scope 30f the invention as United States Patent .PREQ SE CONTROL DI TRIBUT OF AIRlPLANE FUELSTORES Richard A. Muma :and John Lee Markley, Wichita, Kano, :assignors to 'Beech Aircraft Corporation, .Wighita, .Kansx, a corporation of Delaware Application May 8, 1956, sen in 533,599

10 Claims. 01. 137-263 -scribed bydesign of the aircraft.

With growth in the loads of fuel to be carried, the

matter of C.G. control has become progressively more important and various systems for sequencing use of fuel from different tank cells have been developed. These, for the most part, have been complicated, expensive and hardly sufficiently accurate or reliable for practicalsafety requirements.

Accordingly, objects of the present invention are to provide simple, practical and reliable low cost fuel distribution accuratelto -the C-G. limits of the airplane desi readilymnderstood :by users, made up so far as possi-bletof readily replaceable standard parts and units and comprising a system which may be readily installed in airframes now in use and presently under design and development; further, -:to make this system fail safe throughout, :protecting the center of gravity control and enabling use of the main fuel supply after shutdown of the automatic control andtto pennit -dumpingwhile main- :tainingscenteriof gravity control.

The z-foregoing and other important objects attained by thelinvcntion and the movelfeatures of constructiomcom- 'binationtand relation of parts through twhichthe purposes .ofitheliuvention are accomplished are -set forth and will iappearmorefullydn vthe courseIofthe following specificatioh.

The drawing accompanying and forming part of the .spccjficationlisillustrative of present embodiments of the inyention {bl-1t, 1218 will become apparent, structure may be changed 18.8 regards immediate illustration,

.. en efin dand c im EEig. 1 n thetdrawingiisn brokenlplan vview of an air- .ng a lon i u ina tcontroltembodiment of the .inyent on applied thereto in the form of wing tip dividedjncells 1, 1231M 32with thecriticallylocated 1s and 1; a te nate y seque c d "t upp y t a loeate e tersells t. 1s; i -a side v c o QQF/Q th due s cr z uuit wit th timer ndl ansfe pump fo r ng om the and cel s n t e dii t h c te e ind ca e diagrammatically.

.Eis-Ai an e lar d a d par yz ect ned d e ation th wins t p-tan un ra t s wn mat in detail.

4 is afrontview ofan airplaneequipped forlateral c n rolas wins diagrammaticallvs tank 11 4 43 44 and 5 r spec ly sequ n ed: to the nun-c t ente tc ll .3-

;E s. .fli a iagram il ust a in n e tisn nd p atimb the el ment cmb edas inFig. 3.

In the longitudinal control forrn of th li yentionshown inliissza fi. thct wsi ar ue c cre ar c r by .1 2 th nks 7 and 8 d stoth aurilia ysn mam.taaksl ntc arde aitplanc- I l 2,926,688 Patented Mar. 1, 1960 ICC? This fuel supply system in the carrier airplane may be of conventional design with auxiliary and main tanks connected to left and right-hand engine pumps and tanks of the opposite pairs cross connected.

The left and right-hand stores units may be connected with the left and right fuel supply lines of the carrier by break away joints as indicated at 9, Fig. 3.

in the illustration the stores tanks are broken up or divided into the three longitudinally alined cells 1, 2 and 3 with the intermediate or center cells 2 located in non-critical and the end cells land 3 in the critical positions.

These end cells may be of equal capacity, say, 21.5 gallons and the center non-critical cell, designed to be drawn from, of greater capacity, say, twenty-seven gallons.

Fig. 3 shows the fuel transfer line 10 extending from the center cell 2 -to the pull-away fitting at the end of the carrier fuel supply line.

A booster pump 11 in the center tank cell provides the flow from the non-critical tank cell through the transfer line to the engine supply system. This pump, in the example under consideration, might have a capacity of fifty gallons per hour to feed one engine, to cross feed bot-h engines or to feed one engine plus transfer of fuel to refill an auxiliary tank.

Fuel quantity in the center cell is maintained by sequence pumping from the end cells and at much higher rate, for instance in the example given, at one hundred and fifty gallons per hour.

For accomplishing these results, the end cells are manifolded by a connection1-2 having inlets 13, 14 at opposite ends to the cells 1 and 3 and a greater volume positive displacement transfer pump 15 is connected at its inlet side into the manifold at 16 and at its discharge side into themiddle ccll2 at 17.

Dump valves for the end cells are connected into the manifold at 18, 19 and to provide immediate full flow to these valves the opposite ends of the manifold are shown as enlarged to the dump valves, as indicated at 20, 21. The center cell is shown as having a dump valve 22 connected directly thereto.

Suitable controls are provided usually by which the center cell can be dumped separately for ballast control or all three cells be dumped simultaneously as in case of an emergency.

Center of gravity control is retained during dumping by hydraulic balance of the dump manifolds, as shown and described.

Selection of the two end cells is effected in the illustration by normally closed C.G. control solenoid valves 23, 24 in the interconnecting manifold at opposite sides of the transfer pump inlet 16. These selecting valves are in turn controlled by a C.G. control float switch 25 located in the center cell. This may be a two-position switch connected as indicated at 26, 36, with the transfer pump 15 and with-a roto-timer 27 The latter is shown as connected at 28, 29 with the two selecting or sequencing valves 23, 24.

Theseconnections from the float controlled switch are arranged to start the transfer pump 15 and the roto tinier 27 when the float drops to its low positionand to stop th trans rl rn and time whe th flo rises to its p e hi h lc c positi n- Thegoto-timer when started selectfs which valve, either 23 c 24, is to open ,and hence the end cell to restore or to help restore the level oftliquid in the center cell.

A specia .QG- contr floa pe ateds w it h 30 is shown located in the center cell conneptedat 3,1 to turn off the transfer pump 15 and roto-tiiner 27 and close the sequencing valves 23, 2,4 whenfuelis exhausted from the end cells V and the, liquidjn the center cell drops t thi cw n w heate floatsw tshconnected to protect the booster pump 11 from a dry run.

Float opening valves 33, 34 are shown connecting the end cells with the manifold to assure complete draining of these cells in flight attitudes other than level.

A pressure switch 35 is indicated in the intake to the transfer pump, connected to turn off this pump and the roto-timer in case of malfunctioning of the sequencing valves 23, 24.

The roto-timer is constructed and connected to prevent closure of the transfer pump circuit in case of malfunctioning of any type in the timer. These features protect the center of gravity control.

After circuit shut-down of the automatic system, the contents of the center cell, 27 gallons in the illustration, are available for use.

Fig. 5 is a simplified diagram showing electrical connections by which booster pump 11 is started by float switch 25 in the center cell to effect transfer from one of the end cells in accordance with which one of the sequencing valves 23, 24 is selected by the timer 27 which, with transfer pump is connected to be started when the float switch lowers in the center cell.

In the lateral control embodiment of the invention illustrated in Fig. 4, tank cells 41, 42, 44, 45 respectively are disposed in pairs at opposite sides of the center fuselage located center tank 43. The latter is in non-critical position usually at higher level than the side cells as shown.

The outer cells 41 and 45 respectively are shown connected by manifolding sections 12a containing sequencing valves 23a connected with the timer at 28a, and the inner cells 42 and 44 respectively are shown similarly connected by manifolding sections 12b directly connected to the transfer pump and containing sequencing valves 24a having control connections 29a with the timer.

In this manner liquid is alternately drawn from the outer and the inner tank cells to replenish that removed from the center cell.

Since the action of replenishing the center collecting tank from the supply tanks at opposite sides of the same is the same as in the first described form of the invention substantially the same wiring connections may be emploved as indicated in Fig. 5.

By means of differently cut earns the roto-timer may be made to cause the transfer pump to Withdraw equal or unequal amounts of fuel from the different feed tanks and the timing may be such as to keep the transfer pump in action, taking relatively small quantities of fuel from the different tanks in a way to equalize and maintain practically constant C6.

The cells may be simply partitioned portions of a single tank unit or be entirely separate tanks and as has been shown these feed sources may be disposed longitudinally or laterally of a main supply body so terms emploved here are to be thus understood.

The sequence of pumping disclosed assures equal usage of fuel, in the present example, within approximately onehalf gallon limit, and hence for all practical purposes serves to prevent composite fuel center of gravity shift.

The timer selects the proper end or side feed cell for correct sequence and starts the transfer pump and keeps it running long enough to withdraw a volume of liquid which will balance or compensate for that previously removed from an opposing cell or such as will be balanced or compensated bythe following sequencing operation. If the CG. control float switch in the supply cell shuts off the timer before completion of a pumping cycle, the timer will automatically pick up and complete that cycle and then carry on from there on the next energization by the control float.

The system is fail safe" throughout. A solenoid valve and a check valve in the main fuel pressure line of the carrier airplane prevent fuel flow from the carrier back to the stores unit. The pressure switch 35 in the intake aeaaess a to the transfer pump turns off the transfer pump and rototimer in case of malfunctioning of sequencing valves 23 and 24. The rotor-timer 27, is designed to prevent closing of the transfer pump circuit in case of any malfunctioning of the timer, all these features protecting the center of gravity control. Float operated shut-down switch 30 shuts down the CG. control system, should transfer pump 15 become inoperative, so as to prevent continued sequencing of the solenoid transfer valves and possible transfer of fuel through transfer pump by-pass due to static head. When the automatic part of the system shuts down, as it does if anything goes wrong, leaving C.G. properly controlled, the main supply in the center cell continues'ready for use.

The controlled method of operation is accurate and reliable. The parts are relatively few and generally standard units which may be readily assembled and replaced if need be.

Cost of the complete system is reasonable, for results accomplished. Operation is readily understood and necessary controls and indicators may be few and simple in character.

While generally a positive displacement pump may be used as a transfer pump 15, it is contemplated that these transfer operations may be effected by tank cell pressun'zing.

What is claimed is:

1. In combination with an airplane, precise control distribution ofairplane fuel stores comprising a center fuel supply cell located in non-critical position with respect to the center of gravity of the airplane and supplying cells in more critical center of gravity positions at opposite sides of said supply cell, a manifold connecting said side cells, a transfer pump connected at inlet side with said manifold and at discharge side with said center cell, sequencing valves in said manifold at opposite sides of said pump inlet, a timer connected to alternately open said sequencing valves and to hold said transfer pump energized for predetermined intervals of time whereby to feed said center cell with predetermined quantities of fuel taken alternately from the respective side cells and a float actuated switch at said center cell connected to start said timer and transfer pump when fuel in the center cell falls below a predetermined level and to stop said timer and transfer pump when fuel taken from said side cells restores fuel in said center supply cell to the original predetermined level.

2. In combination with an airplane, precise control distribution of airplane, fuel stores comprising a center fuel supply cell located in non-critical position with respect to the center of gravity of the airplane and supplying cells in more critical center of gravity positions at opposite sides of said supply cell, a manifold connecting said side cells, a transfer pump connected at inlet side with said manifold and at discharge side with said center cell, sequencing valves in said manifold at opposite sides of said pump inlet, a timer connected to alternately open said sequencing valves and to hold said transfer pump energized for predetermined intervals of time whereby to feed said center cell with predetermined quantities of fuel taken alternately from the respective side cells, a float actuated switch at said center cell connected to start said timer and transfer pump when fuel in the center cell falls below a predetermined level and to stop said timer and transfer pump when fuel taken from said side cells restores fuel in said center supply cell to the original predetermined level and a shutdown float switch operating at a lower level in said center supply cell and connected to cause closure of said sequencing valves and stoppage of both the timer and transfer pump when fuel in the center supply tank drops to the lower level of said shutdown float switch.

3. In combination with an airplane, precise control distribution of airplane fuel stores comprising a center fuel supply cell located in non-critical position with spect to the center of gravity of the airplane andzsupplying cells in more critical center of gravity positions at opposite sides of said supply cell, a manifold connecting said side cells, a transfer pumpconnected at inlet :side with said manifold and at discharge side with said center cell, sequencing valves in-said manifold at opposite sides of said pump inlet, a timer connectedto alternate'lyopen said sequencing valves and to holdoaid transferupump energized for predetermined intervals of time whereby to feed said center cell with predetermined quantities of fuel taken alternately from the respective side cells, a float actuated switch at said center cell connected to start said timer and transfer pump when fuel in the center cell falls below a predetermined level and to stop said timer and transfer pump when fuel taken from said side cells restores fuel in said center supply cell to the original predetermined level, a boost pump for removing fuel from the center cell and a low level float switch at said center supply cell connected to prevent said boost pump from a dry run.

4. In combination with an airplane, precise control distribution of airplane fuel stores comprising a center fuel supply cell located in non-critical position with re spect to the center of gravity of the airplane and supplying cells in more critical center of gravity positions at opposite sides of said supplycell, a manifold connecting said side cells, a transfer pump connected at inlet side with said manifold and at discharge side with said center cell, sequencing valves in said manifold at opposite sides of said pump inlet, a timer connected to alternately open said sequencing valves and to hold said transfer pump energized for predetermined intervals of time whereby to feed said center cell with predetermined quantities of fuel taken alternately from the respective side cells, a float actuated switch at said center cell connected to start said timer and transfer pump when fuel in the center cell falls below a predetermined level and to stop said timer and transfer pump when fuel taken from said side cells restores fuel in said center supply cell to the original predetermined level and float valves in the side cells at entrances to said manifold.

5. In combination with an airplane, precise control distribution of airplane fuel stores comprising a center fuel supply cell located in non-critical position with respect to the center of gravity of the airplane and supplying cells in more critical center of gravity positions at opposite sides of said supply cell, a manifold connecting said side cells, a transfer pump connected at inlet side with said manifold and at discharge side with said center cell, sequencing valves in said manifold at opposite sides of said pump inlet, a timer connected to alternately open said sequencing valves and to hold said transfer pump energized for predetermined intervals of time whereby to feed said center cell with predetermined quantities of fuel taken alternately from the respective side cells, a float actuated switch at said center cell connected to start said timer and transfer pump when fuel in the center cell falls below a predetermined level and to stop said timer and transfer pump when fuel taken from said side cells restores fuel in said'center supply cell to the original predetermined level, the end portions of the manifold which are connected with the side cells being enlarged and dump valves in said enlarged end portions of the manifold.

6. In combination with an airplane, precise control distribution of airplane fuel stores comprising a center fuel supply cell located in non-critical position with respect to the center of gravity of the airplane and supplying cells in more critical center of gravity positions at opposite sides of said supply cell, a manifold connecting said side cells, a transfer pump connected at inlet side with said manifold and at discharge side with said center cell, sequencing valves in said manifold at opposite sides of said pump inlet, a timer connected to alternately open said sequencing valves and to hold said transfer pump energized :for predetermined f time" whereby to ,feed :said center cell. with predetermined quantities of fuel taken alternately from the respective side cells, a float actuated switch at said center cell connected to start said timer and transfer pump when fuel in the center cell falls below a predetermined level. and to stop said timer and transfer pump when fuel taken from said side cells restores fuel in said center supply cell to the original predetermined level, dump valves in the end portions of said manifold and the center cell having a separate independently operable dump valve.

7. In combination with an airplane, precise control distribution of airplane fuel stores comprising a center fuel supply cell located in non-critical position with respect to the center of gravity of the airplane center of gravity and supplying cells in more critical C.G. posi tions at opposite sides of said supply cell, a manifold connecting said side cells, a transfer pump connected at inlet side with said manifold and at discharge side with said center cell, sequencing valves in said manifold at opposite sides of said pump inlet, a timer connected to alternately open said sequencing valves and to hold said transfer pump energized for predetermined intervals of time whereby to feed said center cell with predetermined quantities of fuel taken alternately from the respective side cells, a float actuated switch at said center cell connected to start said timer and transfer pump when fuel in the center cell falls below a predetermined level and to stop said timer and transfer pump when fuel taken from said side cells restores fuel in said center supply cell to the original predetermined level and a pressure switch located in the intake to the transfer pump and connected to turn off said transfer pump and timer in event of malfunctioning of said sequencing valves.

8. Liquid stores distribution system for holding the center of gravity travel within prescribed limits comprising the combination of a non-critical center of gravity located supply cell from which liquid is taken and critical center of gravity located feed cells for replenishing liquid taken from the supply cell, a pump of limited capacity for removing liquid as needed from the supply cell, a pump of greater capacity for transferring liquid from the feed cells to the supply cell, liquid transfer connections between said feed cells, including sequencing valve means operable to alternate withdrawal from different feed cells, said larger capacity transfer pump being connected at the inlet side with said transfer connections and connected at the discharge side with said supply tank, a timer connected and arranged to time the action of said transfer pump and liquid level control means in said supply cell connected to start and stop said timer in accordance with the level of liquid in the supply cell.

9. Aircraft liquid stores distribution system comprising a center cell and end cells at opposite sides of the same, a supply pump for delivering liquid from the center cell, a transfer pump connected to deliver liquid from the end cells to said center cell, end cell selecting valves, a timer connected to control said selecting valves and volume controlled means at said center cell connected to start said transfer pump and timer when liquid in the center cell is reduced to a predetermined value and to stop said transfer pump and timer when liquid in the center cell is restored to a predetermined value.

10. Aircraft liquid stores distribution system comprising a center cell and end cells at opposite sides of the same, a supply pump arranged to deliver liquid from the center cell, liquid displacement means of greater capacity than said supply pump connected to deliver liquid from the end cells to said center cell, normally closed end cell selecting valves, a timer connected to alternately open said selecting valves and volume controlled means at said center cell connected to start said liquid displacement means and timer when liquid in the center cell is reduced to a predetermined value and to "7 4 s. stop said liquid displacement means and timer when 2,363,622 Rice Nov. 28, 1944 liquid'in the center cell is restored to predetermined 2,394,431 Curtis et al. Feb. 5, 1946 value. 2,557,438 Jo hnsgn June 19, 1951 2,759,424 Defibaugh Aug. 21, 1956 References Cited 1n the file of thls patent 5 FOREIGN PATENTS UNITED STATES PATENT-S 681,361 Great Britain Oct. zz, 1952 2,180,035 Cleghorn Nov. 14, 1939 719,012 Great Britain Nov. 24, 1952

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