Document
Cessna
June 9th, 2009 A Textron Company Airframe Icing Workshop NASA Glenn Research Center
Icing Perspective
Small Airframe Manufacturer’s
NASA/CP—2009-215797 119 Cessna A Textron Company Background/Perspective Icing Effects & Mitigation Icing Certification New Technologies Summary and Recommendations
Agenda
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Background/Perspective
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approval
*
cing
I
nown
K
nto
I
light
F
Two models offer equipment for inadvertent icing
= Certification for
Cessna currently offer ten models with FIKI
Product Line
FIKI
*
NASA/CP—2009-215797 122 Cessna A Textron Company Freezing Point Depressants Freezing Point Depressants Pneumatic Deicers Pneumatic Deicers Bleed Air Thermal Systems Bleed Air Thermal Systems Stabilizer Wing
Speed
525 KTAS 458 KTAS 441 KTAS 435 KTAS 417 KTAS 418 KTAS 389 KTAS 340 KTAS 184 KTAS 186 KTAS 235 KTAS 191 KTAS
Max Cruise
47000 ft 18000 ft 45000 ft 41000 ft 25000 ft 51000 ft
Ceiling
Certified
8,645 lbs 8,750 lbs 8,000 lbs 3,600 lbs 3,400 lbs
MTOW
36,100 lbs 30,000 lbs 20,200 lbs 16,950 lbs 13,870 lbs 12,500 lbs 10,700 lbs
Aircraft
Citation X Citation Sovereign Citation XLS+ Citation CJ4 Citation CJ3 Citation CJ2+ Citation CJ1+ Citation Mustang Grand Caravan Caravan 675 400 Corvalis TT 350 Corvalis
Aircraft Size/Technology
NASA/CP—2009-215797 123 Cessna A Textron Company Transport & Regional Jets Business Jets FIKI Certification Regional Turboprops
(KTAS)
Business Turboprops
High Speed Cruise
cing for Icing Systems I Available Energy Pistons Performance nown Available Aircraft K nto I light F
Service Ceiling
= Certification for
Trends
FIKI NASA/CP—2009-215797 124 Cessna A Textron Company 737 Next Gen 117.4 ft wingspan Citation X 63.9 ft wingspan Increases local water catch rates Increases relative size of ice shapes (w/ respect to chord)
Small leading edges have high water collection rates Typically unpowered flight controls Majority are fixed leading edges
Characteristics of Small Aircraft
43.2 ft wingspan Citation Mustang NASA/CP—2009-215797 125 Cessna A Textron Company ~30% Protected Area ~88% Protected Area Small aircraft typically protect a much larger percentage of the airframe Large proportion of available energy is required for ice protection Protected areas provide the majority of aerodynamic effect on small aircraft
Protected Areas
~90% Protected Area NASA/CP—2009-215797 126
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Icing Effects/Mitigation
NASA/CP—2009-215797 127 Cessna A Textron Company The rate of accumulation is such that deicing/anti-icing equipment Severe -
Avoidance Monitoring Identification and exit
Scale effects limit the ability of small aircraft to operate unrestricted in icing Performance effects can be significant Current ice protection technology can not protect against “severe” icing Severe conditions require FAA Aeronautical Information Manual: fails to reduce or control the hazard. Immediate flight diversion is necessary.
Icing Effects on Small Aircraft
NASA/CP—2009-215797 128 Cessna A Textron Company Training Preflight planning/exit strategies Adherence to operating limitations and procedures Avoidance and exit from severe icing
OPERATION • • • •
Validation of aircraft performance & handling qualities (w/ ice shapes) Validation of ice protection system performance Validation of Operating procedures and Limitations Validation of Abnormal & Emergency procedures
CERTIFICATION • • • •
Aerodynamic Configuration Airframe Ice Protection Systems Engine Ice Protection Systems Air Data Sensors Stall Warning/Protection System Safety Aspects
DESIGN • • • • • •
Risk Mitigation
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Icing Certification
NASA/CP—2009-215797 130 Cessna A Textron Company Small aircraft standards amended in 1993 Large aircraft standards amended in 2007 FAA Guidance/Policy continues to evolve Natural icing is typically a validation of the results of the artificial ice shape testing
Icing certification has taken an increasing role in mitigating icing risk As part of certification, extensive flight testing is performed with artificial ice shapes Artificial ice shapes provide the data used to develop performance information, operating procedures and limitations
Current Icing Certification
NASA/CP—2009-215797 131 Cessna A Textron Company Primarily used for unprotected ice shapes Water catch distributions are also used as input to heat and mass transfer analysis
Most small aircraft manufacturers rely heavily on NASA developed simulation tools LEWICE 2D/3D are the primary ice accretion codes in use for certification LEWICE is also used to provide collection efficiencies and impingement limits that are used in designing protection systems NASA IRT is often used for developing protected area ice shapes for certification
NASA’s Connection to Certification
NASA/CP—2009-215797 132 Cessna A Textron Company With respect to aerodynamic effect Too high of stall speeds adversely affects approach speeds/landing distances Excessive drag can affect performance and climb information
Conservative ice shapes are required for certification However, excess conservatism can have unintended consequences As such, conservative and accurate ice shapes are an objective
Conservative versus Accurate
NASA/CP—2009-215797 133 Cessna A Textron Company Takeoff ice, Final takeoff ice, En route ice, Holding ice, Approach ice, Landing ice, “sandpaper” ice Requires transitions between Appendix C and Appendix X icing conditions
Certification ice shapes are transitioning from a single operating point to scenario based shapes Large droplet rulemaking define scenarios for recognition and exit of conditions Current available version of LEWICE does not address such scenarios
Certification Changes
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FZDZ FZRA
Unrestricted operations Unrestricted in a portion Detect and exit
Draft rulemaking has been proposed for SLD Options include: Simulation and compliance methods are limited Interim methods focus on detect & exit
Future Icing Certification
NASA/CP—2009-215797 135 Instrument (performance) Cessna * * installation effects) (position or A Textron Company Instrument Air Data Sensors Updated FEB 2009 Instrument (performance) ** ** installation effects) * * (position or Instrument * * ** ** (Reference Surface) Visual Cues Detection Methods Fluid Freezing Point Depressant (aft of protected area) Mechanical (protected area) Mechanical (Aft of protected area) Thermal Protected Areas (protected area) Thermal modifications) ** ** ** ** (antenna, inlets, external Non-lifting Surfaces Radome * * * * ** ** Tail Unprotected Areas Wing Codes Codes Codes Codes Tankers Tankers Tankers Tankers Icing Tunnels Icing Tunnels Icing Tunnels Icing Tunnels It may be possible to test small scale installation effects, but large scale installations are not currently feasible Current 2D capabilities exist with large droplet effects, but limitations exist in the use of 3D codes for simulation of Appendix X effects The capability exists today and is suitable to be an element of a means of compliance, or is readily achievable based on current experience The capability is possible, but has not been demonstrated, or there is limited or no validation. The capability is unknown, or does not currently exist * ** FZRA FZDZ FZDZ FZRA MVD < 40μm MVD < 40μm MVD > 40μm MVD > 40μm LEGEND
IPHWG Phase IV Review
NASA/CP—2009-215797 136 Instrument (performance) Cessna * * installation effects) (position or A Textron Company Instrument Air Data Sensors Updated FEB 2009 Instrument (performance) ** ** installation effects) * * (position or Instrument
Small Aircraft
Emphasis Area
* * ** ** (Reference Surface) Visual Cues Detection Methods Fluid Freezing Point Depressant (aft of protected area) Mechanical (protected area) Mechanical (Aft of protected area) Thermal Protected Areas (protected area) Thermal modifications) ** ** ** ** (antenna, inlets, external Non-lifting Surfaces Radome * * * * ** ** Tail Unprotected Areas Wing Codes Codes Codes Codes Tankers Tankers Tankers Tankers Icing Tunnels Icing Tunnels Icing Tunnels Icing Tunnels It may be possible to test small scale installation effects, but large scale installations are not currently feasible Current 2D capabilities exist with large droplet effects, but limitations exist in the use of 3D codes for simulation of Appendix X effects The capability exists today and is suitable to be an element of a means of compliance, or is readily achievable based on current experience The capability is possible, but has not been demonstrated, or there is limited or no validation. The capability is unknown, or does not currently exist * ** FZRA FZDZ FZDZ FZRA MVD < 40μm MVD < 40μm MVD > 40μm MVD > 40μm LEGEND
IPHWG Phase IV Review
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Benefits flying public by improving safety Conserves limited resources
As illustrated, much work remains to mature SLD simulation methods With individual icing tunnel tests on the order of $500k to $1M, no individual manufacturer has the resources to mature simulation methods This effort is best accomplished through joint efforts between NASA and industry
Simulation Efforts
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This area is less mature than SLD and requires significant research and development
Much of the funding for icing research appears to have shifted towards engine/ice crystal research However, the maturity of the SLD simulation methods will likely have a larger near term impact on icing safety Continued development of both the ice crystal and SLD technical areas is recommended
Balance of Needs
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New Technologies
NASA/CP—2009-215797 140 Cessna A Textron Company Energy requirements Aerodynamic effects Weight Reliability Affordability For both Appendix C and SLD
Continued interest in new technology ice protection systems that balance design parameters Severe icing detection methods
New Technologies
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Summary and Recommendations
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Potential accretions aft of protected areas
Particularly combined effects of SLD with ice protection systems
NASA’s simulation tools are essential for aircraft development and certification Artificial ice shapes developed using these tools are fundamental to the certification process Continued maturation of SLD simulation tools are essential for future certifications
Summary
NASA/CP—2009-215797 143 Cessna A Textron Company Current certification standards provide a rigorous evaluation prior to field operations Provides the basis for any aircraft specific training that may be required Changing icing and aircraft conditions, etc. Aligns LEWICE with current regulatory requirements
Atmospheric research that supports a detect and avoid strategy Aircraft level simulation of icing effects Computational simulation of ice accretions during scenarios
Needs/Recommendations
NASA/CP—2009-215797 144 Cessna A Textron Company Can be readily simulated in scale wind tunnel tests Reynolds number issues Improved predictability of full wing stall behavior Ties in with aircraft level simulation of icing effects
Performance of ice shapes with well defined separation features is fairly consistent with scale Roughness based ice shapes still present challenges with respect to scale Ability to effectively model roughness based ice shapes is critical for design and certification
Needs/Recommendations (cont.)
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NASA’s Role
Roadmaps, consortiums, industry cooperative programs Proactive approach to icing safety Addresses the issue before the aircraft are placed in the field
Provide technical leadership Fundamental research to be used in simulation methods Continued support of development and certification tools (with focus on SLD)
Recommendations:
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Questions?
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