Aircraft Anti-Icing SystemsAircraft Anti-Icing SystemsGroup 4Group 4

Leslie MehlLeslie MehlAnnie ParsonsAnnie Parsons

Negative Effects of Ice Negative Effects of Ice BuildupBuildup• Destroys smooth flow of air over Destroys smooth flow of air over wing, leading to severe decrease wing, leading to severe decrease in lift and increase in drag forcesin lift and increase in drag forces

• Can change pitching momentCan change pitching moment• As angle of attack is increased to As angle of attack is increased to

compensate for decreased lift, compensate for decreased lift, more accumulation can occur on more accumulation can occur on lower wing surfacelower wing surface

• Causes damage to external Causes damage to external equipment such as antennae and equipment such as antennae and can clog inlets, and cause impact can clog inlets, and cause impact damage to fuselage and enginesdamage to fuselage and engines

• Considered a cumulative hazard Considered a cumulative hazard because as ice builds up on the because as ice builds up on the wing, it increasingly changes the wing, it increasingly changes the flight characteristicsflight characteristics

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Types of IceTypes of Ice• Rime: “has a rough milky Rime: “has a rough milky

white appearance and white appearance and generally follows the surface generally follows the surface closely”closely”

• Clear/Glaze: “sometimes clear Clear/Glaze: “sometimes clear and smooth but usually and smooth but usually contain some air pockets that contain some air pockets that result in a lumpy translucent result in a lumpy translucent appearance, denser, harder appearance, denser, harder and more difficult to break and more difficult to break than rime ice”than rime ice”

• MixedMixedhttp://virtualskies.arc.nasa.gov/weather/tutorial/images/32clearice.gif&imgrefurl=http://virtualskies.arc.nasa.gov/weather/tutorial/tutorial4.html&h=235&w=280&sz=29&hl=en&start=6&tbnid=NrYdps_943cEmM:&tbnh=96&tbnw=114

Ice DetectionIce Detection• Electronic ice detection common, but can Electronic ice detection common, but can

give false readingsgive false readings• GM is developing a mass based ice detection GM is developing a mass based ice detection

system where ice builds up on external system where ice builds up on external probeprobe

• After mass of probe has increased due to After mass of probe has increased due to additional ice, anti-icing systems are alerted additional ice, anti-icing systems are alerted and turned onand turned on

• This increases fuel efficiency and system life This increases fuel efficiency and system life as de-icing systems are only turned on as as de-icing systems are only turned on as required by conditionsrequired by conditions

Types of Ice RemovalTypes of Ice Removal• Anti-IcingAnti-Icing

– Preemptive, turned on before the flight Preemptive, turned on before the flight enters icing conditionsenters icing conditions

– Includes: thermal heat, prop heat, pitot Includes: thermal heat, prop heat, pitot heat, fuel vent heat, windshield heat, heat, fuel vent heat, windshield heat, and fluid surface de-icersand fluid surface de-icers

• De-IcingDe-Icing– Reactive, used after there has been Reactive, used after there has been

significant ice build upsignificant ice build up– Includes surface de-ice equipment such Includes surface de-ice equipment such

as boots, weeping wing systems, and as boots, weeping wing systems, and heated wingsheated wings

Propeller Anti-IcersPropeller Anti-Icers• Ice usually appears on Ice usually appears on

propeller before it propeller before it forms on the wingforms on the wing

• Can be treated with Can be treated with chemicals from slinger chemicals from slinger rings on the prop hubrings on the prop hub

• Graphite electric Graphite electric resistance heaters on resistance heaters on leading edges of blades leading edges of blades can also be usedcan also be used

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Windshield Anti-IcersWindshield Anti-Icers

• Liquids used include: ethylene glycol, Liquids used include: ethylene glycol, propylene glycol, Grade B Isopropyl alcohol, propylene glycol, Grade B Isopropyl alcohol, urea, sodium acetate, potassium acetate, urea, sodium acetate, potassium acetate, sodium formate, and chloride saltssodium formate, and chloride salts

• Chemicals are often bad for the environmentChemicals are often bad for the environment

• Usually uses resistance Usually uses resistance heat to clear windshield heat to clear windshield or chemical sprays while or chemical sprays while on the groundon the ground

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Thermal HeatThermal Heat• Air HeatedAir Heated

– Bleed air from engine heats inlet Bleed air from engine heats inlet cowls to keep ice from formingcowls to keep ice from forming

– Bleed air can be ducted to wings Bleed air can be ducted to wings to heat wing surface as wellto heat wing surface as well

– Ice can also build up within Ice can also build up within engine, so shutoff valves need to engine, so shutoff valves need to be incorporated in designbe incorporated in design

– Usually used to protect leading Usually used to protect leading edge slat, and engine inlet cowlsedge slat, and engine inlet cowls

• Resistance heaterResistance heater– Used to prevent ice from forming Used to prevent ice from forming

on pitot tubes, stall vanes, on pitot tubes, stall vanes, temperature probes, and drain temperature probes, and drain mastsmasts

Airplane Design, Book 4, Roskam

BootsBoots• Inflatable rubber strips Inflatable rubber strips

that run along the leading that run along the leading edge of wing and tail edge of wing and tail surfacessurfaces

• When inflated, they When inflated, they expand knocking ice off of expand knocking ice off of wing surfacewing surface

• After ice has been After ice has been removed, suction is removed, suction is applied to boots, returning applied to boots, returning them to the original shape them to the original shape for normal flightfor normal flight

• Usually used on smaller Usually used on smaller planesplanes

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Weeping WingWeeping Wing• Fluid is pumped Fluid is pumped

through mesh screen through mesh screen on leading edge of on leading edge of wing and tailwing and tail

• Chemical is distributed Chemical is distributed over wing surface, over wing surface, melting icemelting ice

• Can also be used on Can also be used on propeller blades and propeller blades and windshieldswindshields

•http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22http://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22

Electro-impulse DeicingElectro-impulse Deicing• Electromagnetic coil under Electromagnetic coil under

the skin induces strong the skin induces strong eddy currents on surfaceeddy currents on surface

• Delivers mechanical Delivers mechanical impulses to the surface on impulses to the surface on which ice has formed which ice has formed

• Strong opposing forces Strong opposing forces formed between coil and formed between coil and skinskin

• Resulting acceleration Resulting acceleration sheds ice from the surfacesheds ice from the surface

• Can shed ice as thin as Can shed ice as thin as 0.05”0.05”

•http://www.idiny.com/eidi.htmlhttp://www.idiny.com/eidi.html

Typical Anti-IcingTypical Anti-Icing• C-130: C-130:

– Engine bleed air used for anti-icing wing and Engine bleed air used for anti-icing wing and empennage leading edges, radome, and empennage leading edges, radome, and engine inlet air ducts. engine inlet air ducts.

– Electrical heat provides anti-icing for Electrical heat provides anti-icing for propellers, windshield, and pitot tubes. propellers, windshield, and pitot tubes.

• 777: 777: – Engine bleed air used to heat engine cowl Engine bleed air used to heat engine cowl

inlets. If leak is detected in Anti-Ice duct, inlets. If leak is detected in Anti-Ice duct, affected engine Anti-Ice valves close. affected engine Anti-Ice valves close.

– Wing Anti-Ice System provides bleed air to Wing Anti-Ice System provides bleed air to three leading edge slats on each wing. Wing three leading edge slats on each wing. Wing Anti-Ice is only available in flight. Anti-Ice is only available in flight.

ReferencesReferences• ““Airplane Design, Pt 4.” RoskamAirplane Design, Pt 4.” Roskam• http://www.aopa.org/asf/publications/sa11.pdf#sehttp://www.aopa.org/asf/publications/sa11.pdf#search=%22anti-icing%20systems%20aircraft%22arch=%22anti-icing%20systems%20aircraft%22• http://www.newpiper.com/promo/PIIPS/images/PIIhttp://www.newpiper.com/promo/PIIPS/images/PIIPSPropSlingerRing.jpgPSPropSlingerRing.jpg• http://www.fas.org/man/dod-101/sys/ac/c-130.htmhttp://www.fas.org/man/dod-101/sys/ac/c-130.htm• http://www.airs-icing.org/AIRS_II/AIAAReno2006/AIhttp://www.airs-icing.org/AIRS_II/AIAAReno2006/AIAA-2006-206-739.pdf#search=%22transport%20iAA-2006-206-739.pdf#search=%22transport%20ice%20%22in%20flight%22%22ce%20%22in%20flight%22%22• www.p2pays.org/ref/07/06047.pdfwww.p2pays.org/ref/07/06047.pdf• Ice PicturesIce Pictures• http://www.idiny.com/eidi.htmlhttp://www.idiny.com/eidi.html