59:. As aircraft grew in size and performance, the aerodynamic forces on these surfaces grew to the point where it was no longer possible for the pilot to manually control them across a wide range of speeds - controls with enough advantage to control the aircraft at high speed left the aircraft with significant overcontrol at lower speeds when the aerodynamic forces were reduced. Numerous aircraft in the early stages of
90:". All these systems require three separate components, the hydraulic supply system, the valves and associated control network, and the actuators. Since any one of these systems could fail and render the aircraft inoperable, redundancies are needed that greatly increase the complexity of the system. Additionally, keeping the hydraulic oil pressurized is a constant power drain.
124:
With an EHA, high-power versions of these motors are used to drive a reversible pump, which is tied to a hydraulic cylinder. The pump pressurizes a working fluid, typically hydraulic oil, directly raising the pressure in the cylinder, and causing it to move. The entire system, consisting of the pump,
74:
Starting in the 1940s, hydraulics were introduced to address these problems. In their early incarnations, hydraulic pumps attached to the engines fed high-pressure oil through tubes to the various control surfaces. Here, small valves were attached to the original control cables, controlling the flow
136:
Redundancy can thus be provided by using two such units per surface, and two sets of electrical wires. This is far simpler than the corresponding systems using an external hydraulic supply. Additionally, the EHA has the advantage that it only draws power when it is being moved, the pressure is
354:
137:
maintained internally when the motor stops. This can reduce power use on the aircraft by eliminating the constant draw of the hydraulic pumps. EHAs also reduce weight, allow better streamlining due to reduced internal routing of piping, and lower overall weight of the control system.
46:
and tubing, because they include their own pump, simplifying system architectures and improving safety and reliability. This technology originally was developed for the aerospace industry but has since expanded into many other industries where hydraulic power is commonly used.
128:
Instead of the energy needed to move the controls being supplied by an external hydraulic supply, it is supplied over normal electrical wiring, albeit larger wiring than what would be found in a fly-by-wire system. The speed of the motion is controlled through the use of
163:
113:. Stepper motors are designed to move through a fixed angle with every pulse of current and do so repeatedly in an extremely precise fashion. Both types of motor drives have been in use for years, powering the controls on
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382:
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959:
55:
Aircraft were originally controlled by small aerodynamic surfaces operated by cables, attached to levers that magnified the pilot's input, using
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197:"Review and Analysis of the Reasons Delaying the Entry into Service of Power-by-Wire Actuators for High-Power Safety-Critical Applications"
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196:
954:
899:
764:
1019:
109:
The primary development that lead to the possibility of EHAs was the precision feedback controlled conventional motor, or high-power
75:
of oil into an associated actuator connected to the control surface. One of the earliest fittings of a hydraulic boost system was to
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133:. The result is a "power-by-wire" system, where both the control and energy are sent through a single set of wires.
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The systems evolved, replacing the mechanical linkages to the valves with electrical controls, producing the "
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on late-war models of the P-38L, removing the need for great human strength to achieve a higher rate of roll.
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the cylinder and a reservoir of hydraulic fluid, is packaged into a single self-contained unit.
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253:"Vickers Armstrong (Aircraft) LTD: VC 10; powered flight control units by Boulton Paul"
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303:"Performance of an Electro-Hydrostatic Actuator on the F-18 Systems Research Aircraft"
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160:"FTE New Electro-Hydraulic Clutch Actuator for Automated Manual Transmissions"
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317:"Electrohydrostatic Actuators for Aircraft Primary Flight Control"
86:" design, and more recently, optical networking systems called "
364:
195:
Maré, Jean-Charles (10 September 2021). Uchino, Kenji (ed.).
40:
self-contained actuators operated solely by electrical power
276:"Power By Wire for Aircraft - the All-Electric Airplane"
176:"Lockheed P-38 Lightning Pilot's Flight Manual", pg. 5
101:
airliner known as the
Powered Flight Control Units.
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1219:
1152:
1048:
883:
749:
586:
402:
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8:
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63:suffered from these problems, notably the
215:
151:
42:. EHAs eliminate the need for separate
319:, Technical University Hamburg-Harburg
7:
93:Some of the earliest use was on the
312:, NANASA/TM-97-206224, October 1997
25:
324:"A380: 'More Electric' Aircraft"
166:from the original on 2021-06-02.
1293:In-flight entertainment system
990:Horizontal situation indicator
278:, SAE, #771006, February 1977
1:
119:numeric control machine tools
1273:Environmental control system
355:Electrohydrostatic actuation
349:Electrohydrostatic actuation
18:Electro-hydrostatic actuator
28:Electro-hydraulic actuators
1355:
950:Course deviation indicator
641:Electro-hydraulic actuator
1181:Conventional landing gear
965:Flight management system
1268:Emergency oxygen system
1030:Turn and slip indicator
825:Leading-edge droop flap
795:Drag-reducing aerospike
770:Adaptive compliant wing
765:Active Aeroelastic Wing
1308:Passenger service unit
1109:Self-sealing fuel tank
1005:Multi-function display
351:, Young & Franklin
1288:Ice protection system
1206:Tricycle landing gear
1196:Landing gear extender
413:Aft pressure bulkhead
131:pulse-code modulation
1253:Auxiliary power unit
661:Flight control modes
315:Stefan Frischemeir,
274:C. W. Helsley, Jr.,
57:mechanical advantage
51:Conventional designs
1232:Escape crew capsule
1139:War emergency power
1010:Pitot–static system
855:Variable-sweep wing
563:Vertical stabilizer
265:Frischemeir, pg. 3
217:10.3390/act10090233
940:Attitude indicator
920:Airspeed indicator
915:Aircraft periscope
329:2014-02-22 at the
308:2023-06-01 at the
185:Frischemeir, pg. 2
1334:Aircraft controls
1321:
1320:
1248:Aircraft lavatory
985:Heading indicator
930:Annunciator panel
910:Air data computer
820:Leading-edge cuff
322:Charlotte Adams,
36:hydraulic systems
16:(Redirected from
1346:
1303:Navigation light
1283:Hydraulic system
1258:Bleed air system
1186:Drogue parachute
860:Vortex generator
478:Interplane strut
385:
378:
371:
362:
337:, 1 October 2001
301:Robert Navarro,
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1313:Ram air turbine
1278:Flight recorder
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1129:Thrust reversal
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1044:
1015:Radar altimeter
980:Head-up display
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879:
775:Anti-shock body
757:
745:
606:Artificial feel
588:Flight controls
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448:Fabric covering
398:
394:components and
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345:
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331:Wayback Machine
310:Wayback Machine
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44:hydraulic pumps
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1220:Escape systems
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343:External links
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121:for instance.
115:motion control
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69:P-38 Lightning
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111:stepper motor
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41:
37:
33:
29:
19:
1263:Deicing boot
1191:Landing gear
1134:Townend ring
1124:Thrust lever
1099:NACA cowling
1064:Autothrottle
1056:fuel systems
1054:devices and
845:Stall strips
815:Krueger flap
785:Channel wing
731:Wing warping
721:Stick shaker
716:Stick pusher
640:
636:Dual control
621:Centre stick
488:Leading edge
458:Flying wires
418:Cabane strut
334:
295:Bibliography
283:
270:
261:
247:
239:"Hydraulics"
233:
221:. Retrieved
207:
203:
190:
181:
172:
154:
135:
127:
123:
108:
99:Vickers VC10
92:
88:fly-by-light
81:
73:
61:World War II
54:
31:
27:
26:
1211:Tundra tire
1094:Intake ramp
1025:Transponder
810:Gurney flap
751:Aerodynamic
666:Fly-by-wire
548:Triple tail
223:11 November
95:Avro Vulcan
84:fly-by-wire
34:), replace
1328:Categories
1201:Oleo strut
1089:Inlet cone
1084:Gascolator
1050:Propulsion
1040:Yaw string
1035:Variometer
891:instrument
870:Wing fence
805:Gouge flap
780:Blown flap
736:Yaw damper
711:Stabilator
696:Side-stick
631:Dive brake
518:Stabilizer
493:Lift strut
483:Jury strut
210:(9): 233.
141:References
1339:Actuators
1176:Autobrake
1104:NACA duct
1079:Fuel tank
1069:Drop tank
1052:controls,
935:Astrodome
925:Altimeter
790:Dog-tooth
755:high-lift
706:Spoileron
691:Servo tab
671:Gust lock
626:Deceleron
611:Autopilot
568:Wing root
553:Twin tail
538:Tailplane
473:Hardpoint
443:Empennage
406:structure
204:Actuators
117:rigs and
1144:Wet wing
1119:Throttle
865:Vortilon
726:Trim tab
656:Flaperon
646:Elevator
601:Airbrake
573:Wing tip
498:Longeron
468:Fuselage
404:Airframe
392:Aircraft
357:, Parker
335:Avionics
327:Archived
306:Archived
164:Archived
77:ailerons
1154:Landing
945:Compass
893:systems
885:Avionic
875:Winglet
758:devices
701:Spoiler
596:Aileron
578:Wingbox
503:Nacelle
453:Fairing
396:systems
889:flight
850:Strake
681:Rudder
651:Elevon
616:Canard
558:V-tail
533:T-tail
463:Former
423:Canopy
1074:FADEC
960:EICAS
835:Slats
676:HOTAS
528:Strut
287:Adams
200:(PDF)
146:Notes
38:with
1156:and
1020:TCAS
1000:ISIS
955:EFIS
900:ACAS
887:and
840:Slot
800:Flap
753:and
741:Yoke
513:Spar
438:Dope
225:2022
105:EHAs
67:and
32:EHAs
995:INS
975:GPS
830:LEX
508:Rib
212:doi
1330::
333:,
208:10
206:.
202:.
162:.
71:.
384:e
377:t
370:v
255:.
241:.
227:.
214::
30:(
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.