24TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES AN OVERVIEW OF THE DEICING AND ANTIICING TECHNOLOGIES WITH PROSPECTS FOR THE FUTURE Zdobyslaw Goraj Warsaw University of Technology Keywords: Deicing, antiicing, ice protection equipment Abstract discussion. Basing on statistics of US air carriers [1] in the period 1990-1999 for This paper reviews selected technologies scheduled & nonscheduled airline service devoted to anti-icing and de-icing. Among the related to 89 716 000 departures & 139 027 000 discussed solutions there are Electro-Impulse aircraft hours flown one can figure out the System, Electro_Expulsive Separation Systems following rates (per to 100 000 departures): in a few versions, Weeping Wing Technology • based on De-icing Fluid, Shape Memory Alloys Current accident rate due to icing: 0.00668 • Deicing Technology, Ultrasound Technology General current accident rate: 0.37 and Electrical Heating. Some of these • Percent of accidents due to icing to all technologies are qualitatively compared and accidents: 1.7%. their specific features, including power Modern scheduled aviation has developed consumption, electromagnetic interference and through the years into a reliable economical & environmental issues are discussed. Only a few almost all-weather transport system. Through of these anti-icing and de-icing technologies are the use of ever-improving aerodynamics & commercially available to-day. Some of them engine technology, as well as the increasing use are still immature and need further extensive of light weight composite materials since 1970, investigation and testing in laboratories and in- the SFC has been reduced by more than 30%. flight. Other are commercially available and Radio navigation & approach systems, inertial are certified on older type of small and medium navigation systems, weather radar, ATC etc, in size aircraft. Most of these technologies are combination with ever-improving training and patented. Their full comparison and a selection standardized procedures, allow relatively safe the most safe and in-flight reliable solution for a flight, also in reduced visibility conditions. chosen class of aircraft would be possible if However, in instrument meteorological they are tested in the same laboratory under the conditions, the pilot’s situational awareness is same condition. Coming from this assumption quite poor due to the nonexistence of outside an international research project was proposed, visual altitude, navigation, weather (including which would create objective means for icing conditions) & terrain information. independent assessment of the methods Traditional approach to coping with ice available on the market. Patent descriptions and accretion problem can not be farther used different companies’ websites are widely efficiently, mainly due to the fact that ice is still referred. a reason of fatal crashes (6 well documented crashes of big commercial airplanes in the last 15 years, including 3 fatal accidents with 110 1 Introduction: Statistics and Goal people killed). The need to improve all-weather flying safety is absolutely necessary and beyond of any 1 Zdobyslaw Goraj 2 Worldwide accident’s statistics 0% 10% 20% 30% 40% 50% 60% 70% 80% Flight Crew 91 67% Airplane 15 11% Weather 10 7% Maintenance 8 6% Misc./Other 6 4% Airport/ATC 5 4% Total with 135 known causes Unknown or 65 awaiting reports Number of hull-loss accidents Total 200 Fig.1 Primary cause factors in hull-loss accidents, all airplanes, worldwide commercial Jet fleet, 1990-1999, after Commercial Aviation Safety by Aviation Week, 2001 [1] Landing Generation terrain into flight Controlled Loss of control Midair collision In-flight fire Fuel tank explosion Off end on landing Off sideon landing Hard landing Landed short collapse/fail/up Gear Ice/snow management/exhaustion Fuel Windshear configuration Takeoff takeoff on side Off vehicle/poeple incursion Runway strike Wing Engine failure/separation Ground collision injury crew Ground Boarding/deboarding fatality Turbulence Miscellaneous* Fire on ground structure Aircraft Unknown end off - takeoff Refused Tota l First 54 Second 134 Early widebody 49 Current 148 Total 385 where First Comet 4, 707/720, DC-8, CV-880/990, Caravelle Second 727, Trident, VC-10, BAC 1-11, DC-9, 737-100/200, F-28 Early widebody 747-100/200/300/SP, DC-10, L-1011, A300 Current MD-80, 767, 757, A310, Bae146, A300-600, 737-300/400/500, F-100, A320/319/321, 747-400, MD-11, A340, A330, MD-90, 777, 737NG, 717 Accidents per million departures 0 5 10 15 20 25 First 22.5 Second 2.2 Early Widebody 4.1 Current Fig.2 Accident categories by airplane generation, all accidents, worldwide commercial jet operations, 1990-1990 , after Commercial Aviation Safety by Aviation Week, 2001 [1] 2 AN OVERVIEW OF THE DEICING AND ANTIICING TECHNOLOGIES WITH PROSPECTS FOR THE FUTURE Fatalities 0 500 1000 1500 2000 2500 on–board power & demand very careful maintenance. CFIT* 28 2111(5) Loss of control in flight 29 1902(29) Reliability of such systems usually In-flight fire 3 600 contradicts to the degree of their complexity. It Midair collision 2 469 is especially difficult to accommodate all these Fuel tank explosion 2 238 Landing 14 178(37) traditional systems on smaller commercial Takeoff configuration 3 139(80) transport airplane, for example on business jet, Ice/snow 3 110 Fuel exhaustion 5 100 where weight of additional equipment & its Wind shear 2 91(5) complexity can be a real obstacle to install these Runway incursion 4 30 systems on–board. An example of the Misc. Fatality 3 6 parametrical comparison is presented in Table 1. RTO** 1 5 Total Fatalities = 6655 (6464 onboard) Turbulence 3 3 1999 fatalities = 361 (onboard) On ground 3 2 Table 1 Some features of EMEDS technology [47] compared to traditional Pneumatic Boots Unknown 7 482(223) Number of total accidents: 112 Parameter modern traditional *CFIT = Controlled Flight Into Terrain technology: technology: **RTO = Refused Takeoff EMEDS Pneumatic Note: Accidents involving multiple, non-onboard are included boots Accidents involving single, non-onboard are excluded erosion metal elastometric Fig.3. Fatalities by accident categories, fatal accidents, surface worldwide commercial jet fleet, 1990-1999, [1] surface life life of aircraft months, rather not years, An example: depending on • ATR-72 accident, Roselawn, Indiana, service Oct.31, 1994, all passengers (72) killed drag no increase measurable • Embraer 120, Monroe, Michigan, Jan.9, increment increase 1997, 29 passengers & crew members deice ice as thin as typically killed. performance 0.12 cm greater than & no upper 0.6 cm 3 State-of-the-art in aircraft ice protection limit Weight equivalent baseline Anti-ice aircraft protection should be Cost equivalent baseline based on deep knowledge of flight physics, electric power 25 amp* 28 V zero meteorology and icing phenomenon. In the for 12 m span DC = 0.7 kW relevant bibliography one can find a lot of books, papers and reports [2-39] describing the methodology of icing research and results 4 A review of modern technologies obtained from measurements and numerical simulation. 4.1 SPEED - Sonic Pulse Electro-Expulsive A traditional approach to coping with ice Deicer includes pneumatic deicing boots (usually used on propeller–driven aircraft), thermal anti–icing The Sonic Pulse Electro-Expulsive Deicer systems (to de-ice wing leading edges & (SPEED) is an acceleration based deicer for propeller leading edges & engine air intakes), aircraft ice protection [41]. The system was glycol based fluid (usually used to protect wing developed in collaboration with NASA Lewis surfaces & propeller leading edges). All these and ARPA’s SBIR program. SPEED evolved systems are highly complicated, need a lot of from the Electro-Impulsive deicing (EIDI) concept with a major improvement in the actuator coil and electronics. This is due to a 3 Zdobyslaw Goraj special multiple winding actuator that is seated in the leading edge substructure. As in EIDI, actuator coils are strategically placed behind the leading edge to apply impulsive loads directly to the aircraft skin or outer surface material. The rapid acceleration debonds and sheds ice into the airstream in a very efficient manner (ice layers can be shed as thin as 12 mm). SPEED represents the most technically advanced low power deicing system available. IDI’s (Innovative Dynamics Inc.) Icing Onset Sensor (IOS) can be added to the basic system to Fig.5 Original sketch from US Patent 6,102,333, provide an autonomous mode of operation. The Innovative Dynamics, Inc. IOS detects the initiation of ice accretion (icing onset) and continuously monitors the amount of accumulation. When the accumulation reaches a 4.2 The electro-impulse method thickness threshold at which efficient clearing is possible, the sensor commands the deicer to fire. The electro-impulse method was first patented Because the sensor continuously monitors the in England in 1937 [62]. Wichita State accumulation, the sensor can determine if the University extensively tested this method both ice was properly shed or if another clearing in wind tunnel and in flight using NASA Twin cycle is required. The sensor continues to Otter aircraft, [18]. monitor accretion and initiate deicing cycles as required. The IDI deicing technology has been extensively tested both in ice tunnels and in flight. It has been selected by Raytheon for use on the Premier I aircraft, scheduled for FAA certification in 2000. The design is protected by U.S. Patent Number 6,102,333. IDI company underlines the following features of the SPEED Fig.6 NASA Twin Otter used for the Electro-Impulse solution: Electrically operated; Very low power Method testing consumption; Erosion resistant; Low cost solid state design; Reliable and maintenance-free; When the high-voltage capacitors are rapidly Fault-tolerant operation and; Graceful discharged through the coils installed just inside degradation (of aircraft performance). the skin of the aircraft leading edge, the result is a sudden electromagnetic repulsive force in the skin which throws ice in all directions.