Airliner brake performance

Some of FlightGear's airliners brake unrealistically well. To support aircraft modelers, this page collects typical maximum decelerations of real-world airliners, achived in real-world RTO tests or otherwise documented.

From all data I could collect so far, airliners' brakes typically generate a mean deceleration in the 3-4 m/s² range.

RTO and brake test videos on YouTube

A380 brake test

http://www.youtube.com/watch?v=m1dv_y_3EK0

Mean deceleration is given there as 3.62 m/s²

MD-80 Baseline Rejected Takeoff Test

http://www.youtube.com/watch?v=cieuEe7-lsg

Accelerates slightly above 180 kt, starts braking at 1:40 into the vid, you hear "50" at 1:57, yields 130 kt in 17 seconds, hence mean deceleration 3.9 m/s²

747-8 RTO

http://www.youtube.com/watch?v=DpLPkDLGVjk

Reporter mentions initial speed of "Above 200 miles or 320 km/h", brakes applied at 1:03, aircraft halts at 1:33. Mean deceleration would be 3 m/s²

A340-600 RTO

http://www.liveleak.com/view?i=cd3_1312399258

The crew applies brakes when reaching V₁ at 0:48, the plane stops at 1:17, so that's 29 seconds from V₁ to stop. Now what's the value of V₁? I estimated it using the length of the centerline markers. When announcing "100", the gear passes by one such dash in 19 frames. When announcing "V₁", just before braking, it's one dash in 10 frames, which translates to V₁ = 190 kt. So, from 190 kt to 0 in 29 seconds yields 3.4 m/s².

747 Flight Crew Ops Manual

For max manual braking, no thrust reversers:

Landing dist = ref dist + weight correction + no thrusters

Braking dist = landing dist - 1000 ft (==305 m)

At 200 t

V_ref30 = 127 kt

Landing dist = 1010 m - (15 m / 5 t) * (250 t - 200 t) + 75 m = 935 m

Braking dist = 935 m - 305 m = 630 m

Mean deceleration a = V_ref30² / (2 * braking dist) = 3.39 m/s²

At 400 t

V_ref30 = 184 kt

Landing dist = 1010 m + (20 m / 5 t) * (400 - 250 t) + 75 m = 1685 m

Braking dist = 1685 m - 305 m = 1380 m

Mean deceleration a = 3.25 m/s²

How to perform RTO test in FG

I did some tests with the 787-8 by Omega95. Static friction is set to 0.9 in Aircraft/787-8/Nasal/gear_system.nas. Decelerating from 185 kt to 50 kt (KEDW Rwy 17 is a nice place for that) using full brakes only (no spoilers etc) then takes only 12 seconds, yielding 5.6 m/s².

Setting static friction to 0.5, it takes 21 seconds to go from 185 kt to 50 kt (3.18 m/s²), and another 7 s to halt (3.4 m/s²). So, values around 0.5 seem to be far more reasonable.