SAWE Report - Cal Poly San Luis Obispo

Table 11.VIII - Landing Flight Profile
1. Approach from 50 ft obstacle on 3º glide slope
2. 1.15g pull-up for flare – touchdown at 1.2 V stall
3. Roll for 3 s
4. Brake and apply thrust reversers until stopped
MIL-C5011A defines field length to be the distance required to takeoff and clear a 50 ft (15.2 m)
obstacle or the distance to land from a 50 ft (15.2 m) obstacle. Takeoff and touchdown speed are
defined as 1.2 times the aircraft’s stall speed, and the speed over the 50 ft (15.2 m) obstacle must
be greater or equal to 1.3 times the stall speed for both takeoff and landing. The takeoff gross
weight for the design mission of 124,800 lb (56,610 kg) was used for the aircraft weight for both
takeoff and landing calculations. This allows the aircraft to land immediately after takeoff
without the need to jettison fuel or weapons. Takeoff and touchdown speeds were always greater
than the required 1.2 stall speed because of the acceleration during the 3 second rotation and roll
periods. During takeoff, due to the high speeds of the aircraft, the 50 ft (15.2 m) obstacle was
cleared before the climb angle was reached, so the climb segment of the profile was ignored.
Also, to simplify the calculations, the landing simulation was run backward so that the
touchdown point could be found without having to calculate the altitude and speed at the
beginning of the flare necessary to have the touchdown occur at the correct altitude and speed.
The results of the takeoff and landing simulations that are listed in Table 11.IX and Table 11.X
show that the RFP requirements for takeoff and landing on an icy 8,000 ft (2,438 m) runway are
met.
Table 11.IX - Takeoff Results
Weight
124,800 lb (56,610 kg)
Maximum lift coefficient 1.2
Stall speed 242 ft/s (73.7 m/s)
Takeoff speed 266 ft/s (81.1 m/s)
50 ft obstacle speed ≥ 290 ft/s (88.4 m/s) 326 ft/s (99.4 m/s)
Rolling friction coefficient 0.025
Runway length 3,842 ft (1,171 m)
Field length over 50 ft obstacle 5,280 ft (1,609 m)
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