(19) &   

(11) EP 2 202 151 A2

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication: (51) Int Cl.: 30.06.2010 Bulletin 2010/26 B64D 15/14 (2006.01)

(21) Application number: 09176205.4

(22) Date of filing: 17.11.2009

(84) Designated Contracting States: (72) Inventor: Botura, Galdemir C. AT BE BG CH CY CZ DE DK EE ES FI FR GB GR North Canton, OH 44720 (US) HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK SM TR (74) Representative: Cummings, Sean Patrick et al Designated Extension States: Keltie AL BA RS Fleet Place House 2 Fleet Place (30) Priority: 17.11.2008 US 115264 P London EC4M 7ET (GB)

(71) Applicant: Goodrich Corporation Charlotte, North Carolina 28217-4578 (US)

(54)

(57) An ice protection system (40) is provided for an (51-55), and input channels (71-79) which conveys data aircraft surface having a plurality of ice-susceptible re- to the controller (60). The controller (60) uses the chan- gions. The system (40) comprises an ice protector nel-conveyed data to determine optimum operation for (51-55) for each ice-susceptible region, a controller (60) each of the ice protectors and controls the supply elec- which independently controls each of the ice protectors trical energy thereto in accordance with such optimiza- tion. EP 2 202 151 A2

Printed by Jouve, 75001 PARIS (FR) 1 EP 2 202 151 A2 2

Description below, the regions 31-35 are simply a conceptual map- ping tool and they are determined by the placement of [0001] Ice can accrete on exposed or otherwise sus- ice protection components (protectors 51-55 introduced ceptible surfaces of an aircraft when it encounters super- below). The aircraft surface 30 does not need, and prob- cooled liquid. When ice accretes on airfoil surfaces, such 5 ably will not have, any structural features defining region- as wings and stabilizers, shape modifications occur al perimeters or boundaries. which typically increase drag and decrease lift. And ice [0006] In the illustrated embodiment, the regions are accretion on engine inlet lips can disrupt desired flow arranged in three rows (a, b, c) and each row has five patterns and/or contribute to ice ingestion. To avoid per- consecutive regions (31, 32, 33, 34, 35). Regions are formance problems during flight, an ice protection system 10 characterized as consecutive if they precede one after must be able to shield an aircraft from the most extreme the other in a substantially fore-aft direction. Thus, de- icing conditions. picted regions31a - 35a could be considered consecutive regions, depicted regions 31b - 35 b could be considered SUMMARY consecutive regions, and depicted regions 31c - 35c 15 could be considered consecutive regions. [0002] An aircraft ice protection system comprises a [0007] Depending upon the aircraft 10 and the partic- controller, a plurality of consecutive ice protectors, and ular aircraft component, more or less rows, and/or more information input channels. The ice protectors can be or less regions-per-row may be more appropriate. With independently controllable by the controller and, depend- the 18 and/or the pylon 22, for example, ing upon channel-input information, they can operate in 20 a single row of consecutive regions and as few as two either an anti-icing mode or a deicing mode. In this man- regions may be sufficient. And the congregation of re- ner, ice protection can be accomplished effectively and gions in regular (or irregular) rows is certainly not re- efficiently for specific flight circumstances, instead of rig- quired. In the same regard, the aircraft surface 30 need idly expending power that would be required to remedy not be segmented into rectangular or similarly shaped the most extreme ice impingement conditions. 25 regions as shown; the regions 31-35 can comprise a col- lection of sectors of varying sizes and/or geometries. DRAWINGS [0008] While the regions appear in a flat array in the drawing, this is simply for ease in illustration and expla- [0003] nation. In most instances, the regions will form a curved 30 profile wrapping around the associated aircraft structure. Figure 1 is a perspective view of an aircraft having Specifically, for example, the region 31 will form one end several surfaces protectable by the ice protection of the curve, the region 35 will form an opposite end of system. the curve, and the regions 31-34 will extend therebe- Figure 2 is a schematic diagram of one of the air- tween. craft’s surface and the ice-susceptible regions ther- 35 [0009] If the surface area 30 is on one of the wings 14, eon. the regions 33 could be curved about the wing’s leading Figure 3 is a schematic diagram of the ice protection edge, the regions 31-32 could be upper regions, and the system, with ice protectors associated with one of regions 34-35 could be lower regions. The rows could the aircraft’s surfaces. extend spanwise across the wing 14. An analogous ar- Figure 4 is a schematic diagram of the ice protection 40 rangement could be used if the surface area 30 is on one system, with ice protectors associated with several of the horizontal stabilizers 16. of the aircraft’s ice-susceptible regions. [0010] If the surface area 30 is on the vertical stabilizer 18, the regions 33 could likewise curve around the lead- DESCRIPTION ing edge. The remaining regions 31 - 32 could be right- 45 side regions and the remaining regions 34-35 could be [0004] An aircraft 10, such as that shown in Figure 1, leftside regions. The regions 31-33 could be likewise lo- can comprise 12, wings 14, horizontal stabiliz- cated if the surface area 30 is on one of the pylons 22. ers 16, a vertical stabilizer 18, engines 20, and pylons [0011] If the surface area 30 is on one of the engines 22. The wings 14 are the aircraft’s primary lift providers. 20, the regions 33 could be wrapped about the The horizontal stabilizers 16 prevent up- down motion of 50 inlet lip and the rows (a, b, c) could extend radially there- the aircraft nose, and the vertical stabilizer 18 discour- around. With such a circular profile, the regions 31-32 ages side to side swinging. The engines 20 are the air- could be outer regions and the regions 34-35 could be craft’s thrust-providing means and the pylons 22 serve inner regions. as underwing mounting means for the engines. [0012] Referring now to Figure 3, the aircraft ice pro- [0005] As shown in Figure 2, each wing 14, stabilizer 55 tection system 40 is schematically shown. The system 16/18, engine 20, and/or pylon 22 has a surface 30 that 40 comprises an ice-protector grid 50 associated with can be viewed as having a plurality of consecutive ice- the relevant aircraft surface 30 and the grid 50 comprises susceptible regions 31-35. As is explained in more detail an ice protector 51-55 for each ice-susceptible region

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31-35. Thus, with the illustrated regions 31-35, the ice rule (keeping in mind that real life frequently disagrees protectors are arranged in three rows (a, b, c) and each with general rules), ice will not form during flight unless row has five consecutive ice protectors (51-55). The ice the temperature reaches the freezing threshold .This protectors 51-55 can each comprise an electrothermal temperature input can be used, for example, in the de- heater that converts electrical energy into heat energy. 5 termination of whether icing conditions are present and, [0013] The ice protection system 40 also comprises a if so, the severity of such conditions. controller 60 that controls the supply of electrical energy [0019] An input channel (e.g., channel 72) can corre- to the ice-protector grid 50. At least some of the ice pro- spond to region specific temperatures (RST) of the rele- tectors 51-55 can be independently controllable by the vant aircraft surface 30. When supercooled drops contact controller 60. An independently-controlled ice protector 10 an aircraft surface 30 that is below 0° C, they will freeze. has its own supply path of electrical energy and this sup- With large supercooled drops, the freezing process is ply can be adjusted by the controller 60 autonomously relatively gradual (due to the release of latent heat) re- of the other protectors. sulting in runback and an increased likelihood of clear [0014] At least some of the independently-controlled ice formation. Tiny supercooled drops, on the other hand, ice protectors 51-55 are multi- mode ice protectors. Each 15 will freeze on contact, into easily removable lime ice. multi-mode ice protector can be selectively operated in Troublesome clear ice formation usually occurs at below one of an anti-icing mode, a deicing mode, and an inac- freezing. While rime ice is most commonly encountered tive mode. In the anti- icing mode, electrical energy is con- with OATs in the -10° C to -20° C range. tinuously supplied to ice protector 51-55 for an extended [0020] The input channels 71 and 72 can together con- period of time (e.g., greater than 10 seconds) to prevent 20 veyinformation to the controller 60 that can help ascertain ice from forming on the corresponding region 31-35. In the chance of clear ice formation. If these channels 71/72 the deicing mode, electrical energy is intermittently sup- collectively signal a high chance of clear ice creation plied (e.g., for distinct periods of time separated by at (e.g., an OAT hovering near 0° C and a RST below 0° least 10 seconds) to the ice protector 51-55 to episodi- C), the controller 60 can aggressively supply electrical cally remove ice form on the corresponding region. And 25 energy to runback-risk regions (e.g., aft regions 31 and in the inactive mode, electrical energy is not supplied 35)to curtail such formation. If the channels 71/72 instead (and is not scheduled to be supplied) to the ice protector suggest the strong possibility of rime ice (e.g., an OAT 51-55 for an extended period (e.g., more than 120 sec- below -10° C and a RST below 0° C), less assertive meas- onds). ures can be adopted. [0015] All of the ice protectors 51-55 in the grid 50 can 30 [0021] Additionally or alternatively, the input channel be capable of multi-mode operation as this may afford 72 can relay temperature information regarding areas the most embracing portfolio of operational patterns outside the ice-protected regions 31-35. If non-ice-pro- and/or facilitate modular manufacturing and inventory. In tected regions of the aircraft surface 30 (e.g., non-heat- many instances, however, certain ice protectors need ed) are below freezing, runback solidification can be con- only operate in one of an anti-icing mode and a deicing 35 cern. If this challenge presents itself, the controller 60 mode, regardless of climate conditions and/or flight cir- can strategically deprive the aft-most regions 31 and 35 cumstances. For example, on a wing 14 or stabilizer of heat so as to, for example, build temporary dams to 16/18, the fore-most protectors 33 could be dedicated block water flow beyond the protected regions. anti-icing components and/or the aft- most ice protectors [0022] An input channel (e.g., channel 73) can be de- 31/35 could be dedicated deicing components. 40 voted to data about aircraft altitude (ALT). Icing is rare [0016] The controller 60 can further be adapted to pro- above 2500 meters because any clouds at this altitude vide one, some or all of the ice protectors 51-55 with a generally contain already-frozen water droplets. If the range of power draws ( e.g., 100%, 50%, 75%, 25% etc.). channel 73 indicates an acceptably high altitude, and no These different power draws can be accomplished by other information signifies icing apprehension, the con- direct voltage reduction, if possible and practical. Addi- 45 troller 60 can relax the ice protectors into inactive modes. tionally or alternatively, a range of non- zero power draws If the channel 73 indicates a lower altitude, this indication can be created by an incessant series of on- off modula- in combination with other data (e.g., OAT readings) can tion increments (e.g., 150 millisecond increments) sum- be used to tailor optimum ice protection operation. ming into a resultant anti-ice or deice time period. [0023] An input channel (e.g., channel 74) can be re- [0017] The ice protection system 40 further comprises 50 lated to aircraft speed (SPEED). A general rule is (again, an input-channel constellation 70 comprising a plurality remembering that general rules often have exceptions), of input channels 71-79. The channels sense, measure, that the swifter the speed, the warmer the relevant sur- detect, receive, or otherwise obtain information during face 30, and the less chance of icing incidences. While flight and convey this data to the controller 60. The con- speed will usually not alone dictate appropriate ice-pro- troller 60 then controls the supply of electrical energy to 55 tection parameters, it may be a helpful ingredient in the the ice protectors 51-55 based on this information. overall analysis. Additionally or alternatively, speed in- [0018] An input channel (e.g., channel 71) can corre- puts can also alert the controller 60 to sudden changes spond to outside air temperature (OAT). As a general in aircraft travel, and may be a determinative factor in

3 5 EP 2 202 151 A2 6 choosing between two otherwise adequate options. length); the flight phase becomes quite significant. The [0024] An input channel (e.g., channel 75) can corre- controller 60 can be programmed to notch up ice protec- spond to the (AOA) at this particular point tion on the horizontal stabilizers 16 if the channel 76 con- of flight. The angle of attack typically changes significant- veys that the aircraft 10 is an approach/landing phase. ly during aircraft climb/descent. And in any event, a var- 5 [0030] An input channel (e.g., channel 77) can be used iance in the angle of attack almost always causes a mi- to provide the controller 66 with information regarding gration of airfoils’ stagnation lines. the position of movable parts of the aircraft 10. These [0025] While anti-icing is persistently viewed as oblig- movable parts typically comprise control surfaces hinged atory at a stagnation line, deicing is usually deemed suit- or otherwise movably attached to fixed aircraft compo- able at locations immediately adjacent (i.e., fore) thereto. 10 nents such as the wings 14 and/or the stabilizers 16/18. If multi-mode ice protectors 52-54 reside on non-aft re- The wings 14 can have, for example, for roll, gions 32-34, the controller’s knowledge of the stance of flaps or slats for lift enhancement, and/or spoilers for lift the stagnation line allows anti-icing (e.g., very power in- reduction. The horizontal stabilizers 16 can have eleva- tensive) to be confined to this location and deicing (e.g., tors for up-down deflection and the vertical stabilizer 18 less power consuming) to be employed at adjacent loca- 15 can have a for left-right deflection. tions. This energy-saving advantage can be further en- [0031] The positioning of movable parts during can hanced by the regions 33 and ice protectors 53 replaced heighten the importance of ice protection on certain air- with several thin regions/protectors. A strip-like (rather craft surfaces 30. For example, if wing flaps are deployed than patch-like) geometry can permit fine-tuned pro- to improve lift coefficient, such deployment will also in- gramming of mode selection to closely follow the stag- 20 tensify nose-down pitching moment and thereby amplify nation shift. the download duty of the horizontal stabilizers 16. With [0026] An angle of attack can additionally or alterna- the input channel 77, the controller 60 can be notified of tively influence the relative ice accumulation on the dif- part movement and adjust ice- protection parameters ac- ferent regions of an aircraft surface 30. A greater angle cordingly. of attack, for example, can often cause less ice on upper 25 [0032] An input channel (e.g., channel 78) can be used aft regions and more ice on lower aft regions. The con- to convey cloud characteristics to the controller 60 as the troller 60 can use the conveyed AOA data in the formu- aircraft 10 encounters such cast members. This informa- lation of the best (and probably non-symmetrical) oper- tion could be obtained, for example, by meteorological ation of the upper/lower ice protectors. satellites and screened for alignment with the aircraft’s [0027] An input channel (e.g., channel 76) can corre- 30 global position. As icing depends largely upon cloud spond to the flight phase of the aircraft 10. Ice issues structures, such data would certainly be beneficial in the generally introduce themselves with the greatest inci- controller’s creation of the most advantageous ice-pro- dence during non-cruise flight phases (e.g., takeoff, tection strategy. climb, and approach). This is because, in part, there is a [0033] Cumulus clouds (i.e., clouds have heaping cau- greater probability of encountering liquid water at the low- 35 liflower-like appearances) present the greatest icing con- er altitudes traveled during these phases. cerns worries at OATs between 0° C and -20 °C, with [0028] And regardless of altitude (and even with cloud- less cause for concern at OATs between -20° C and - less skies and temperatures above freezing) icing con- 40° C. At OATs less than -40° C, icing fears essentially cerns may lurk within engines 20 during taxing and take- vanish with cumulus clouds. With a stratiform cloud (i.e., off. During pre- cruise flight phases, reduced pressure ex- 40 a cloud having a vertically thin layer-like appearance), ists within the engine intakes, which can lower tempera- the most aggressive ice protection steps are necessary tures to such a degree that condensation and/or subli- at OATs between 0° C to -15° C, less aggressive steps mation takes place. If the input channel 76 indicates that are necessary at OATs between -15° C to -30° C, and at aircraft 10 is in the taxiing phase or the takeoff phase, less than. Thus, an OAT at -35° C corresponds to either and the channel 71 indicates an OAT less than 10 C, the 45 a medium (cumulus) or low (stratiform) alert level de- controller 60 can initiate preventive measures. It may be pending upon cloud structure. noted that, during other flight phases, a temperature of [0034] Cloud structure aside, freezing rain and drizzle 9° C would not trigger any increased awareness. should be cautiously heeded when the OAT is at or below [0029] The flight phase of the aircraft 10 can also be 0° C. Clear ice is most likely to form in freezing rain, a used to reprioritize the deicing hierarchy. The horizontal 50 phenomena comprising raindrops that spread out and stabilizers 16, for example, normally take a back seat to freeze on contact with a cold aircraft structure. As clear the main wings while in the cruise phase. But these com- ice has a tenuous personality, the controller 60 can be ponents can become increasingly important during the programmed to treat potential clear-ice conditions with approach/landing phase of a flight (due to increased pitch the utmost care and caution. control demand). Enter into the equation that the hori- 55 [0035] An input channel (e.g., channel 79) can be used zontal stabilizers 16 can collect proportionally two to to provide information concerning liquid water content in three times more ice than wings (due to the relatively the ensuing airstream. The channel 79 can be fed infor- small radius and the wing-dwarfed chord mation by, for example, an instrument sensor mounted

4 7 EP 2 202 151 A2 8 on the outside of the aircraft 12. (See e.g., http:// Claims ntrs.nasa.gov/archive/nasa/casi.ntrs /.nasa.gov/20090- 022002 200902156.) A liquid water content up to 0.125 1. An ice protection system (40) comprising at least one g/m3 could correspond, for example, to trace intensity ice protector (51-55) that is a multi- mode ice protec- with barely perceptible ice formations on unheated air- 5 tor switchable from operation in an anti-icing mode craft surfaces. The controller 60 therefore could be pro- to operation in a deicing mode, or vice-a-versa, de- grammed to rest the ice protectors 51-55. A liquid water pending upon a non-temperature input; content of 0.125 g/m3 to 0.25 g/m3 and a liquid water wherein, in the anti-icing mode, each multi- mode ice content of 0.25 g/m3 to 0.60 g/m3 could correspond to protector (51-55) is operated to continuously prevent moderate ice intensities and the controller 60 could be 10 ice from forming on a corresponding region (31-35); adapted to bolster its attack upon receiving such data. and Channel-conveyed LWC data upwards of 0.60 g/m3 wherein, in the deicing mode, each multi-mode ice could trigger the controller 60 in a watchful stance protector (51 -55) is operated to intermittently re- whereat it monitors icing conditions with escalated dili- move ice formed on the corresponding region gence. 15 (31-35); and [0036] In the ice protection system 40 shown in Figure wherein, in an inactive mode, each multi-mode ice 3, the ice protectors 51-55 are associated with one air- protector (51-55) is not operated. craft surface 30 and the controller 60 optimizes the ice protection of the regions 31-35 of such surface based on 2. An ice protection system (40) as set forth in claim 1, data input through the channel constellation 70. As20 having a plurality of consecutive protectors ice- shown in Figure 4, the ice protectors 51-55 for several (51-55) that proceed one after another in a substan- of the aircraft surfaces 30 can be controlled by the same tially fore-aft direction, these ice protectors including controller 60 based on the channel- input data. The latter the multi-mode ice protector(s). arrangement may facilitate overall aircraft power optimi- zation, as it allows the controller 60 to take into consid- 25 3. An ice protection system (40) as set forth in claim eration the aircraft’s overall ice protection needs. 1or claim 2, further comprising: [0037] One may now appreciate that with the aircraft ice protection system 40, the ice protectors 50 can be a controller (60) independently controlling each operated so as to most effectively and efficiently address- of multi-mode ice protectors (51-55) depending es the flight circumstances, instead of rigidly expending 30 upon the non-temperature input; the power required to remedy the most extreme ice im- and input channels (71-79) which convey opti- pingement conditions. mum-control-determining data to the controller [0038] Although the aircraft 10, the aircraft surface 30, (60), this data including the non- temperature in- the system 40, the grid 50, the controller 60, and/or the put. channelconstellation 70 have been shown anddescribed 35 with respect to a certain embodiment or embodiments, 4. An ice protection system (40) as set forth in any of it is obvious that equivalent alterations and modifications claims 1 to 3, wherein each ice protector has an elec- will occur to others skilled in the art upon the reading and trothermal heater which converts electrical energy understanding of this specification and the annexed into heat; drawings. In regard to the various functions performed 40 wherein, when an ice protector is in an anti-icing by the above described elements (e.g., components, as- mode, electric energy is substantially continuously semblies, systems, devices, compositions, etc.), the supplied to this multi-mode ice protector to prevent terms (including a reference to a "means") used to de- ice from forming on the corresponding region; scribe such elements are intended to correspond, unless wherein, when an ice protector is in a deicing mode, otherwise indicated, to any element which performs the 45 electrical energy is intermittently supplied to the ice specified function of the described element (i.e., that is protector to remove ice formed on the corresponding functionally equivalent), even though not structurally region; and equivalent to the disclosed structure which performs the wherein, whenan iceprotector is in an inactive mode, function. In addition, while a particular feature of the in- electric energy is not supplied to the ice protector. vention may have been described above with respect to 50 only one or more of several illustrated embodiments, 5. An ice protection system (40) as set forth in claim 4, such feature may be combined with one or more other wherein at least some of the ice protectors (51-55) features of the other embodiments, as may be desired operate only in the anti-icing mode and the inactive and advantageous for any given or particular application. mode and/or wherein some of the ice protectors 55 (51-55) operate only in the deicing mode and the inactive mode.

6. An ice protection system (40) as set forth in claim 4

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or claim 5, wherein at least some of the ice protectors tible region on each of these aircraft surfaces. (51-55) can be selectively operated at different non- zero power draws in the anti-icing mode and/or the deicing mode. 5 7. An ice protection system (40) as set forth in any of claims 4 to 6, wherein at least one input channel (71, 72) provides temperature data to the controller (60) and at least one input channel (73-79) provides the non-temperature data to the controller (60); and 10 wherein the controller (60) uses both the tempera- ture data and the non- temperature data to determine an optimum mode of operation for each of the multi- mode ice protectors (51-55). 15 8. An ice protection system (40) as set forth in claim 7, wherein the temperature data corresponds to the outside air temperature (OAT).

9. An ice protection system (40) as set forth in any of 20 claims 1 to 8, for an aircraft surface having a plurality of consecutive ice-susceptible regions (31-35) that proceed one after another in a substantially fore-aft direction, and one of the ice protectors (51-55) being associated with each ice-susceptible region of the 25 aircraft surface.

10. An ice protection system (40) as set forth in claim 9, wherein the non-temperature data comprises at least one of altitude (ALT), aircraft speed (SPEED), 30 angle of attack (AOA), flight phase (PHASE), and part position (PART).

11. An ice protection system (40) as set forth in claim 9, wherein the non-temperature data comprises at 35 least two of altitude (ALT), aircraft speed (SPEED), angle of attack (AOA), flight phase (PHASE), and part position (PART).

12. An ice protection system (40) as set forth in claim 9, 40 wherein the non-temperature data comprises at least three of altitude (ALT), aircraft speed (SPEED), angle of attack (AOA), flight phase (PHASE), and part position (PART). 45 13. An ice protection system (40) as set forth in any of claims 9 to 12, wherein the non-temperature data includes cloud characteristics (CLOUD) and/or liquid water content (LWC). 50 14. An aircraft comprising at least one aircraft surface (30) and the ice protection system (40) set forth in claim 9.

15. An aircraft as set forth in claim 14, comprising a plu- 55 rality of aircraft surfaces (30) and the ice protection system (40) set forth in claim 9, wherein each ice protector (51-55) is associated with an ice-suscep-

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