Transcript Slide 1
Cessna Model 162 (Skycatcher) Spin Compliance/Safety Lessons Learned C. Dale Bleakney (M) Cessna Engineering Flight Test1 Introduction – What is an LSA? ASTM 2245-xx: Max gross TO weight: 1320 lbs Min useful load - 430 lbs Vs min - 45 KCAS Vh max - 120 KCAS SE, fixed gear, fixed pitch prop 2 Cessna LSA History Program Launch – Friday, January 13, 2006 Proof of Concept 1st Flight: Friday, October 13, 2006 Prototype 1st Flight: March 7, 2008 Wichita Built P1* 1st Flight: April 30, 2008 *P1 = Production No. 1 3 Model 162: Final Configuration Wing Span 30 ft Wing Chord 4 ft Cabin Width 44.3 in Flaps 0° Stall 44 KCAS Flaps 40° Stall 40 KCAS Usable Fuel 24 gal 4 Instrument Panel 5 Spin Program Overview In 1980, the US Supreme Court concluded that "Safe" is not the equivalent of "risk-free." LSA Spin Testing Goal: Safe, Thorough, Efficient ASTM 4.5.9: ….(4) For the flaps-extended condition, the flaps may be retracted during recovery. 14 CFR 23.221 ….. For the flaps-extended condition, the flaps may be retracted during the recovery but not before rotation has ceased. The rules are technically identical, Therefore: Spin matrix was defined using FAA Advisory Circular 23-8B: 352 spin conditions 6 Safety Equipment/Process •First flight •Chute & Helmet •Chase aircraft w/video •Special Inspection •First Flight Readiness Review (FFRR) •Envelope expansion •Chute & Helmet •Chase aircraft •Stalls •Chute, Helmet, BRS (Aft cg) •Spins •BRS, Chute, Helmet •Chase aircraft w/video •Spin FFRR 7 Spin Program Weather/Test Constraints **Before 1st Spin Event Weather Ceiling – MIN 10,000 feet Surface Winds – MAX 10 knots with 5 knot gusts (chute limits) Spins per sortie No MAX - BUT fatigue will be watched Crew Rest MAX - 5 flying days per week NO work or flights on Sunday 8 Spin Matrix and Buildup Program Before 1st Spin Event Spin Matrix – Buildups (¼ , ½, 1 turn) Fwd cg, idle power Normal - flaps - up / down Turning - flaps - up / down Abused - flaps up / down Repeat with power on - Buildup to MCP Repeat at aft cg - Idle, then buildup to MCP 9 Safety Systems Overview Crew Entry/Egress Removable Door – 2 action Procedure practiced before 1st flight Spin Chute (Options) BRS Whole Airplane Chute –CHOSEN Tail mounted airplane spin chute – NOT CHOSEN 10 Spin Event No. 1 – September 18, 2008 BUILDUP Spins Successfully Completed: Fwd cg Idle/MCP Fwd cg MCP abused (ailerons with) Event SPIN: MCP, ailerons against: 3+ turns KEY FACTS 143 Successful spins completed Key spin characteristics identified: All spins were ASTM and 23.221 compliant Redundant safety systems and safety discipline - ALL important 11 Spin Event No. 1 - Lessons Learned Safety Systems BRS Spin Chute - Did not deploy Rotation rates and spin attitude contributed to improper rocket trajectory and failure Changed BRS parachute installation design Door Jettison - Dual action door delayed bailout Other Buildups - Did not forecast event 12 Risk Mitigation/Event analysis – Post Event No.1 Internal Review •Flight Test •Project / Advanced Design Outside Assistance •Former Cessna Test Pilots •Retired Cessna Aero / Advanced Design •BIHRLE •NTPS 13 Post Spin Event No. 1 BRS Design Changes OLD Canister Type Installation NEW Bed Mount Installation Parachute Actuation Handle Soft Pack Design – No Canister Parachute Bag - Oriented horizontally and near window Rocket aft of parachute - Close proximity to window. No way it will catch on anything on the way out. Cessna designed truss Supports both parachute and rocket Built in deflectors/guides Rocket 14 Post Event No. 1 - Door Release Changes Removable hinge pins Single Emergency Release Handle 15 Post-Event No. 1 - Bihrle Spin Tunnel testing Power model updated Predicted delayed spin recovery Now matched event No. 1 spin New vertical stabilizer w/ ventral Spin tunnel data - No unrecoverable spin modes 16 Safety Equipment/Process Spin Briefings (Before and after 1st Event) Include standard test card items FTE monitors air-to-air frequency Standard debrief, data review, and characteristics review Missing elements (Lessons learned after 1st Event) Telemetry Ground crew at spin sight Instrumentation Control positions Body angle of attack Real-time pilot feedback 17 Revised Spin Matrix – Post Event No. 1 Buildup redefined (look at aft cg earlier) Idle – fwd cg, then aft cg then, MCP – fwd cg, then aft cg Note: 2000 rpm to MCP (100 rpm at a time) 28 to 33% MAC (1% at a time) 18 Spin Videos – Mod 1 Configuration Idle, Flaps Up, Right Idle, Flaps 10, Left 19 Risk Mitigation – Post Event No. 1 SAME •Chase Aircraft •Spin Chute – BRS •Personal safety equipment •Brief and debrief NEW •Fly the spin aero simulator before each new configuration •Go/No go as part of pre-flight brief •Post spin discussion of characteristics-to-simulator correlation •Detailed characteristics discussions with Flight, Aero, Safety •NO-GO decision is okay – Proceed with caution •Same as before but with increased emphasis •High definition video for post-spin analysis Detailed flight reports to the Chief Pilot, Safety to independently assess positive and negative characteristics of each spin before we proceed. 20 Spin/Stall Progress Chart Cessna Model 162 Stalls/Spins 1400 1366 800 1263 1207 1200 1219 700 1171 Total stalls Total Spins 1087 600 1000 No. of Stalls 813 806 800 500 835 468 439 439 400 663 600 596 492 We are now here 400 200 141 98 66 82 102 132 0 1/1/08 3/1/08 5/1/08 7/1/08 300 283 213 363 236 375 346 324 200 151 143 118 143 100 73 51 24 6 9/1/08 No. of Spins 531 920 0 11/1/08 1/1/09 3/1/09 5/1/09 7/1/09 9/1/09 21 Spin Event No. 2 - 3/19/2009 COMM antenna damaged during BRS deployment No communication with chase airplane Rotation would not stop until engine shutdown Pilot Door Jettison – Failed (Door opened but would not jettison) BRS saved the Pilot – Impact still substantial (approx. 1600 fpm) 22 Tail Change No. 2 Original design Original tail (Mar 08) Rev 1 tail (Sep 08) Rev 1 Design Rev 2 (V4) Design 20% larger vertical tail 10º less rudder sweep Removed dorsal fin Shielded rudder horn (directional stability) Added ventral fin (not shown) Rev 2 tail (V4) (Mar 09) Increased rudder span Ventral moved further aft Maximum UP elevator changed from 30° to 22° 23 Spin Compliance Completion Plan Check Stability and Control/Stalls Look for max AOA change: Reduced max elevator travel (from 30° to 22°) Power-on stall checked – lower AOA/better characteristics Power-off stall speed checked - still ASTM compliant Spin Compliance New spin chute –Aft cg testing only (due to aft truss/chute mount) New spin matrix (with buildup) Redo critical case spins without spin chute/with BRS 24 Post Event No. 2 Safety/Flight Procedure Changes Check Door Release, then re-attach before every spin flight Maximum of 12 spins per sortie. Maximum of 2 sorties per day 1 spin pilot – Pick up on subtle cues between spins Early morning flights only – reduce pilot fatigue Real time feedback from telemetry room on entry/recovery on every spin 25 Spin Compliance Matrix (Post No. 2) Original Spin Matrix 352 Total Spins Fwd then aft cg Idle then MCP Power Turning – over-the-top/under-the-bottom Abused – ailerons with/against Remaining untested spins (with spin chute) 92 Total Spins Aft cg – Normal Aft cg – Turning Aft cg – Abused (ailerons with, ailerons against, Idle/MCP) Final Spins (without spin chute, with BRS) Aft cg – Normal (IDLE), Normal (MCP) MCP Abused (ailerons against) (Problem Spin) 26 Spin Video – Final (Flaps 10, MCP, abused , Left , Ail Against) With spin chute Without spin chute 27 Spin/Stall Progress Chart Cessna Model 162 Stalls/Spins 1400 1366 800 1263 1207 1200 1171 Total stalls Total Spins 1087 1219 700 FINISHED 7/17/2009 600 1000 No. of Stalls 813 806 800 500 835 468 439 439 400 663 600 375 346 324 596 492 213 363 236 200 141 98 66 82 102 132 0 1/1/08 3/1/08 5/1/08 7/1/08 300 283 400 200 151 143 118 143 100 73 51 24 6 9/1/08 No. of Spins 531 920 0 11/1/08 1/1/09 3/1/09 5/1/09 7/1/09 9/1/09 28 Spin Event Summary September 18, 2008 (28% MAC) (Event No. 1) March 12, 2009 (30% MAC) (3 turn recovery) BRS failure, Pilot bailed out Analyzed and thought to be caused by distributed ballast March 19, 2009 (32% MAC) (Event No. 2) (28%, 30%, 31% MAC successfully completed with new ballast configuration) 32% MAC – recovery not seen after approx 3 turns ∙ ∙ ∙ ∙ Pilot rode airplane to ground ∙ ∙ BRS deployed Communication antenna lost Jettison malfunctioned Door release malfunctioned minor injuries to pilot damage to airplane – most damage was after impact July 17, 2009 (32% MAC) Spins successfully completed (with and without spin chute) Stall and spin characteristics significantly improved Final spin completed - 1 turn recovery. Meets ASTM and FAR 23 29 Summary of Lessons Learned 1. Get recent spin practice in a similar airplane 2. Spin Tests should be done last - Final aero configuration 3. Look for excess flight control travels and limit them as necessary 4. Watch for subtle clues. Stall characteristics were a big clue. 5. NO two airplanes and NO two spins are identical (snowflake effect) 6. Safety systems must be robust. (Video) 7. TM data with experienced pilot feedback was very helpful 8. ¼ and ½ turn spin buildup did not predict 1 turn behavior However, it does acclimate and tune the pilot 30 162 Program - Interesting Statistics Are you superstitious ??? LSA Program go: Friday, Jan 13, 2006 POC First flight: Friday, October 13, 2006 First POC cross-country: AOPA, Palm Springs, CA Flight 13, 1300 NM, took 13 hours Spins First Proto spin event, Spin 13, Thur, 9/18/08 Second P1 spin event, Spin 13, Thur, 3/19/09 Final P1 spin flight, Flight 169 (13 squared) No more than 12 spins a day were done with the version 2 tail. Don’t give the big guy a free shot – superstition or not 31 Questions? Fun at Mach 0.162 32 Post Event No. 1 Aerodynamic Configuration Changes Original Proto configuration Post Event No. 1 configuration 1. 2. 3. 4. Dorsal removed Ventral added Vertical stabilizer chord increased Vertical stabilizer sweep angle decreased 33 Spin Video – MCP Abused (Final –W/O Spin Chute) Flaps 10, MCP, Left Spin, Ailerons Against – w/o chute 34 Post Spin Event No. 1 - BRS Design Changes (Details on Next Slide) OLD Canister Type Installation NEW Soft pack Installation 35 Bihrle Testing - Post-Event No. 2 Bihrle Test Matrix Baseline with flaps 10 Baseline plus dorsal (Event configuration) Three new vertical stabilizers (+20% area) Baseline vertical + 5-in chord extension (V1) New vertical with 10-deg sweep reduction (V4) New vertical with zero sweep (V5) Vented elevator Horizontal stabilizer moved aft Additional aileron deflections Additional down elevator deflection Conclusion Selected V4 with/without ventral for simulation (see next slide) 36 Post Event No. 1 Aerodynamic Configuration Changes Vertical Stabilizer Changes V1 V4 Thorough!! Area (ft2) LE Sweep (deg) HL Sweep (deg) Rudder/Stabilizer Chord Ratio Stabilizer V1 8.7 42.9 31.6 0.50 Stabilizer V4 10.4 37.3 21.6 0.40 37 Spin Video – Normal Spin Rev 1 Configuration: Flaps Up, Idle, Left Spin 38 Spin Video: Idle, Normal Spin Mod 1 Configuration: Flaps Up, Left Turn (Note Entry) 39 Spin Event No. 2 - 3/19/2009 Potential Causes Change in perceived AOA at stall/spin entry – Too much elevator?? BRS Spin Chute – Deployed but would not jettison Rotation rate, spin attitude, inability to jettison BRS ∙ High rotation rate caused risers to twist and increased friction in release pin attachment ∙ Friction forces caused cable stretch – pilot unable to generate enough force to pull the release pin 40 Stall/Spin Progress Chart Cessna Model 162 Stalls/Spins 1400 1366 800 1263 1207 1200 1219 700 1171 Total stalls Total Spins 1087 600 1000 No. of Stalls 813 806 800 500 835 Over 600 stalls completed before the first spin 663 600 439 400 492 141 98 66 82 102 132 0 1/1/08 3/1/08 213 363 200 5/1/08 7/1/08 300 283 400 236 439 375 346 324 596 We are here 468 200 151 143 118 143 100 73 51 24 6 9/1/08 No. of Spins 531 920 0 11/1/08 1/1/09 3/1/09 5/1/09 7/1/09 9/1/09 41 Spin/Stall Progress Chart Cessna Model 162 Stalls/Spins 1400 1366 800 1263 1207 1200 1219 700 1171 Total stalls Total Spins 1087 600 1000 No. of Stalls 813 806 800 500 835 468 439 439 400 663 600 375 346 324 596 492 213 363 236 200 141 98 66 82 102 132 0 1/1/08 3/1/08 5/1/08 7/1/08 300 283 400 200 151 143 118 143 100 73 51 24 6 9/1/08 No. of Spins 531 We are920here 0 11/1/08 1/1/09 3/1/09 5/1/09 7/1/09 9/1/09 42 Spin Video: MCP – Abused Spin Mod 1 Configuration: Flaps Up, Left, MCP Ailerons Against 43 BRS Installation (Before 1st Event) Actuation Handle Safe FWD 44 Spin Program Schedule – Before 1st Spin Event -Efficient -Test Team (Pilot’s share spin sorties approx. 50/50) Dale Bleakney – Project Pilot Bob Newsome – Contract Pilot (former T-6A Test Pilot, and spin pilot) Bob Rice – Assistance flying spins after first event Andrew Thorson – FTE (in chase airplane) Ahmed Mohamed – FTE (ground data analysis) -Sortie Generation Rate 2 – 3 sorties per day Spin Pilot/Chase Pilot alternate - Reduce fatigue 45 162 Configuration Change Summary September 2008 Original Configuration March 2009 Rev 1 Configuration Post Event No. 1 1. 2. 3. 4. Dorsal removed Ventral fin added Vertical stab chord increased Vertical sweep angle decreased June 2009 Rev 2 Configuration Post Event No. 2 1. 2. 3. 4. Rudder extended Ventral fin move aft Ailerons geared (reduce adverse yaw) Up elevator reduced from 30° to 22° (Significant) 46 Aileron Change – Reduced Adverse Yaw Pre 3-19-2009 aileron configuration 20° up/ 15° down Post 3-19-2009 aileron configuration 20° up/ 5° down (less adverse yaw) 47 Summary – Lessons Learned - 2 1. Safety Spin chutes are proven technology. Design them in at the beginning Spin tests should be done last in a program after all aero data are gathered. Otherwise, you may end up repeating the spin tests. 2. Get recent spin practice in a similar airplane 3. NO two airplanes and NO two spins are identical (snowflake effect) NO covenants with past programs. There may not be a correlation. 4. Watch for subtle clues. Stall characteristics were a big clue. Reluctant to reduce up elevator due to stall speed impact - BIG 5. Safety systems MUST be robust. 6. TM data - essential. 7. Experienced pilot feedback from TM - invaluable. 48 Model 162 Configurations Pre-September 2008 (Original) Post-September 2008 (Event No. 1) Increased vertical, added ventral Post-March 2009 (Event No. 2) (Final) Ventral Moved Aft, Rudder Extended Elevator UP Reduced, Aft cg limit Reduced, Ailerons re-geared 49 Compliance Spin Test Status Completed Power Off – Fwd/aft cg wings level Fwd/Aft cg turning Fwd/aft cg abused controls Power On – Fwd/aft cg wings level Incomplete Conditions Power On – Abused (Aft cg) Power On – Turning (Aft cg) 50 Ventral Variants Small ventral Large ventral Large ventral installed at a more aft location on the airplane is a potential option in work 51 Spin Test Status Stability & Control, Dive, Stall, Performance Testing – Complete Spins - 241 Conditions complete Power Off – Complete Fwd/aft cg wings level Fwd/Aft cg turning Fwd/aft cg abused controls Power On – Complete Fwd cg wings level Spins Remaining – 111 Conditions MCP – Aft cg - wings level – Turning (Fwd and Aft cg) – Abused (Fwd and Aft cg) 52 Flight Test Data Spin Comparison Summary Spin Rate (deg/s) Spin Rate (deg/s) CG Power Flaps Rudder Aileron Flight Spin Bef Recovery Input Aft Recovery Input Difference From Baseline 32 MCP 10 Left Right 140 13 92 216 - 28 MCP 10 Left Right 135 14 111 166 CG 31 MCP 10 Left Right 139 13 104 154 CG 32 2200 10 Left Right 140 12 98 196 Power 32 MCP 0 Left Right 140 10 94 174 Flaps 32 MCP 10 Left Neutral 132 7 97 193 Aileron 32 MCP 0 Right Left 140 11 93 113 Right Spin In each of the following slides, the event spin data are shown as solid lines, and the comparison spin data are shown as dashed lines. In each slide, one variable is changed from the event spin. 53 Flight Test Data CG=31%, MCP, Flaps=10°, Left Rudder, Right Aileron Solid line - Flight: 140 Spin: 13 Dashed line - Flight: 139 Spin: 13 50 [deg] Ele. Pos. Rud. Pos. 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 AOP 100 [deg] 3250 AOR 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 50 [deg] ALPSL ALPSR 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 HDG 100 [deg] 3250 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 54 Flight Test Data CG= 32%, 2200 RPM, Flaps 10°, Left Rudder, Right Aileron Solid line - Flight: 140 Spin: 13 Dashed line - Flight: 140 Spin: 12 50 [deg] Ele. Pos. Rud. Pos. 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 AOP 100 [deg] 3250 AOR 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 50 [deg] ALPSL ALPSR 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 HDG 100 [deg] 3250 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 55 Flight Test Data CG=32%, MCP, Flaps=0°, Left Rudder, Right Aileron Solid line - Flight: 140 Spin: 13 Dashed line - Flight: 140 Spin: 10 50 [deg] Ele. Pos. Rud. Pos. 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 AOP 100 [deg] 3250 AOR 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 50 [deg] ALPSL ALPSR 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 HDG 100 [deg] 3250 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 56 Flight Test Data CG= 32%, MCP, Flaps=10°, Left Rudder, Neutral Aileron Solid line - Flight: 140 Spin: 13 Dashed line - Flight: 132 Spin: 7 50 [deg] Ele. Pos. Rud. Pos. 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 AOP 100 [deg] 3250 AOR 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 50 [deg] ALPSL ALPSR 0 -50 3210 3215 3220 3225 3230 3235 3240 3245 HDG 100 [deg] 3250 0 -100 3210 3215 3220 3225 3230 3235 3240 3245 3250 57 Flight Test Data CG=32%, MCP, Flaps 0°, Ailerons Against Spin (Solid-Line=Left Spin, Dashed-Line=Right Spin) Solid line - Flight: 140 Spin: 10 Dashed line - Flight: 140 Spin: 11 50 [deg] Ele. Pos. Rud. Pos. 0 -50 2870 2875 2880 2885 2890 2895 2900 2905 AOP 100 [deg] 2910 AOR 0 -100 2870 2875 2880 2885 2890 2895 2900 2905 2910 50 [deg] ALPSL ALPSR 0 -50 2870 2875 2880 2885 2890 2895 2900 2905 HDG 100 [deg] 2910 0 -100 2870 2875 2880 2885 2890 2895 2900 2905 2910 58 Agenda Detail Airplane Configuration Review of SkyCatcher configurations flown to date Comparison between SkyCatcher and Cessna 152 Geometry Wing geometry Tail volume coefficients Aileron to wing area ratio Rudder to vertical tail area ratio Elevator to horizontal tail area ratio Flap to wing area ratio Mass properties comparison 59 Backup Slides LSA Geometric Comparisons Cessna SkyCatcher Cessna 152 Flight Design CTSW Fore/Aft Length Ratio 0.42 0.41 0.40 Engine Pitch (deg) 4 0 5 Forward CG 26.0% 23.7% 32.5% 18% 20% Aft CG 32.0% 30.2% 40.6% 31% 33% Elevator Chord Ratio 0.40 0.41 1 0.44 1 Horizontal Tail Volume Coefficient 0.55 0.46 0.52 0.66 0.47 Rudder Chord Ratio 0.4 0.4 ~.5 ~.32 0.35 Vertical Tail Volume Coefficient 0.038 0.032 0.040 0.046 0.052 Aileron Chord Ratio 0.20 0.19 0.21 0.15 0.23 Aileron Flapped Area Ratio 0.32 0.50 0.31 0.43 0.40 Flap Flapped Area Ratio 0.49 0.38 0.53 0.52 0.45 Wing Loading 11.0 10.4 12.3 11.2 10.2 Remos GX Tecnam P92 Eaglet 0.40 0.42 ~0 60 Backup Slides LSA Geometric Comparisons Cessna SkyCatcher Cessna 152 Flight Design CTSW Remos GX Tecnam P92 Eaglet Ventral Area (ft2) 1.1 0 5 2 0 VT/Rudder below Horizontal Yes Yes No No No MTOW (lbs) 1320 1670 1320 1320 1320 S wing (ft2) 119.9 160.0 107 118 129 48.0 59.0 46 50 55 359.8 400.0 336 366 342 1.5 1.0 1.7 22.2 28.5 18 22 21 142.9 154.0 144 173 157 10.4 12.5 10 12 15 159.1 165.0 146 168 153 total aileron area (ft2) 7.6 17.9 7 8 11 elevator area (ft2) 8.8 11.3 18 10 21 rudder area (ft2) 4.8 6.1 4 3 4 mac (in) b wing (in) dihedral wing (deg) S horizontal (ft2) horizontal tail arm (in) S vertical (ft2) vertical tail arm (in) 1.5 61 Model 162/152 Comparison Geometry Model 162 Model 152 22.15 28.52 Elevator Area (ft2) 8.80 11.30 Elevator Area Ratio 0.40 0.40 Elevator Chord Ratio 0.40 0.41 Horizontal Tail Volume Coefficient 0.55 0.46 10.44 12.45 Rudder Area (ft2) 4.78 6.10 Rudder Area Ratio 0.46 0.49 Rudder Chord Ratio 0.40 0.40 0.039 0.032 Horizontal Stabilizer Area (ft2) Vertical Stabilizer Area (ft2) Vertical Tail Volume Coefficient 62 Model 162/152 Comparison Mass Properties 152 Full Fuel, MTOW 162 Flight 140 Weight (lb) 1670 1351 Wing Loading (lb/ft2) 10.4 11.3 Ixx* (slug*ft2) 706 599 Iyy* (slug*ft2) 703 625 Izz* (slug*ft2) 1220 1077 Ixz* (slug*ft2) 72 53 * Weights Group Calculations 63