Impact OF A380s on guidance signs IES ALC 2015 Impact OF A380s on guidance signs October 21, 2015 COMPREHENSIVE REPORT OF CFD ANALYSIS

Evaluation of Wind-Loading on Airport Signs FAA Technical Note published in June 2000 investigated the forces exerted on airport signs caused by jet blast and wake turbulence Key findings & conclusions led to incorporating changes to FAA AC 150/5345-44F, with specific emphasis on third mode of signs designed to withstand wind loads > 300 mph with a 2.0 psi load factor Recommended for use of Mode 3 sign where airports have history of sign failures, especially with heavier transport like B747-400s Aircraft Type Engine Trust 747-400 747-400ER PW 63,300 lbf (282 kN) GE 62,100 lbf (276 kN) RR 59,500/60,600 lbf (265/270 kN) ER: GE 62,100 lbf (276 kN) Source: DOT/FAA/AR-TN00/32, June 2000 and Boeing

Dawn of Super Jumbo Entered services in October 2007 171 A380s have entered the fleets of 13 operators and 146 in orders The A380 fleet operates more than 100 routes to 48 global destinations, taking off or landing every four minutes on average Providing relief to dense, high-yield traffic flowing and severely capacity constrained airports or Hubs Introduced “super-heavy” wake vortex category, relatively high runway occupancy time as well as line-up times Increasing A380 operations at major hubs show more operational challenges for legacy airport infrastructure Airport Weekly Operations Dubai Intl (DXB) 297 London Heathrow (LHR) 104 Singapore Changi (SIN) Paris (CDG) 94 Frankfurt (FRA) 76 Seoul (ICN) 75 Los Angeles Intl (LAX) 70 Sydney (SYD) 47 Source: Airbus, Aviation Week & Space Technology

A380 & Airport Infrastructure Geometry On Runway On Taxiway 19.8m 30.2m

A380 Engine Diameter and Positions GP 7200 Outboard engine distance to edge – 19.3m (63.3 ft) Inboard engine distance to edge – 30.2m (99.1 ft)

A380 – Rolls Royce Trent 900 Engines Source: Airbus

A380 – GP Alliance GP7200 Engines Source: Airbus

Typical Guidance Sign Size

Geometry Created in CFD Top-down view Guidance Sign Front looking back The 3D-CAD tool in Star-CCM+ was used to create geometry Screenshots of the engine and sign geometry are shown below Engine

Effects of Increasing Wind Velocity Simulated CFD simulations for 100, 200, 300, and 400 mph head wind were performed Engines and wing tip vortices were not included According to the standards, the sign will break when the pressure on the sign reaches 1.3 psig Using this assumption, the sign will break for a wind velocity of 296 mph These wind velocities are associated with the strongest category of tornadoes and are very unlikely to occur under normal circumstances At this velocity, the force on the sign is 3830 lb Wind Velocity (mph) Max Pressure on Sign (psig) Force on Sign (lb) 100 0.14 420 200 0.58 1710 300 1.34 3960 400 2.36 7290

Velocity Contours for 300 mph Wind Significant wake region exists behind the sign Sign expected to break for this case

Engines Alone Do Not Produce Breaking Force Engine blast was simulated in two locations Per Geometry described earlier Maximum force on sign due to engines alone approximated by aligning the outboard engine with the sign Plume does not strike the sign for standard conditions (see next slide) When outboard engine is lined up with the sign, the force is much smaller than needed to break the sign The plume is therefore not the sole cause of the sign damage Because of this, secondary effects, such as wing tip vortices, must be considered Engine Location Max Pressure on Sign (psig) Force on Sign (lb) Default 2 Aligned 0.26 710

CFD Image of Velocity Contours Narrow plume – essentially no impact on the runway sign for normal conditions

Tip Vortices can Cause Significant Damage Force on Sign Time history of force on the sign shown below Cases where engines are 144 and 240 ft away from sign First 2 seconds not shown – solution still stabilizing Average force and peak pressure calculated for each case Instantaneous maximum force and peak pressure also extracted Strong buffeting is evident – force can vary by over 2000 lbs for 144 ft case Force and Pressure on Sign Results for the four tip vortex cases are shown below Force on sign reaches a maximum when engine about 150 ft from sign Peak force is near 3000 lb – this is relatively close to the breaking point If other factors are included, such as wind or other random effects, this could cause the sign to break Jet rotation could also increase the forces on the sign – this was not simulated for the present report Buffeting could also increase impact of these forces Variation of force on the sign is small when vortex is generated closer to the sign Beyond wind and jet blast, it was theorized that the cause of damage could be buffeting from wing tip vortices for a heavy lift aircraft A circular disc will be added to introduce tip vortices The tip vortex will be introduced at the tip of the wing, as shown below The vortex will be represented by a circular disc of radius 5.8 m The vortex core has a radius of 2 m, so the vortex boundary includes tip vortex effects beyond the vortex core Engines, along with tip vortex inlet, were positioned at four axial distances from the sign 240 ft – approximate length of an A380 144 ft – 60% of A380 length 72 ft – 30% of A380 length 36 ft – 15% of A380 length Time (s) Time (s)

Streamlines from Airplane – Case of 144 ft Guidance Sign

Visual of Aircraft Wing Tip Vortices Image shows that vortices can be strong and affect the runway guidance signs Source: Airline.net

Exhaust/Ground Interaction at Rotation Side view Top view These images show velocity contours (top) and a velocity isosurface (bottom) for an airplane during rotation When exhaust plume strikes the ground, it spreads more quickly, expanding the influence of the exhaust

Conclusions A wind of 296 mph is required to reach the breaking pressure of 1.3 psi on the guidance sign, current Mode 3 sign as per AC 150/5345-44K up to 300 mph The plume of an A380 engine is not strong enough to cause sign damage Two major causes contributing to sign damage due to A380 operations are: Wing tip vortices cause strong buffeting forces on the signs and can be responsible for breaking them Jet rotation could also increase the pressure on the signs due to exhaust interaction with the ground Need for fresh look at Lighted Sign Wind and Frangibility requirements to meet A380 operations Picture: AirTeamImages.com