Juan Vela
Filing Flight Plan
- Joined
- Apr 29, 2017
- Messages
- 5
- Display Name
Display name:
mistervela
Hey guys, I'm getting mixed answers with this problem: (Below is the attached performance table)
Cessna C-150. Calculate the takeoff ground run and total takeoff distance on a grass runway. QNE = 2500 ft; OAT = +20 °C; Headwind = 5 Kts; Max takeoff weight; Flaps up.
The answer is: 917 ft and 1637 ft
I calculated the Ground Roll and Total take off distance by interpolating:
[1] 910-630=280; 280 / 2=140; 630+140=770ft for Ground Roll
[2] 1660-1250=410; 410/2 = 205; 1250+205 = 1455 ft for Total Take off
[3] For a grass runway: 7% of 1455 = 101.85
[4] ISA Temperature at 2500ft = 15-2(2500/1000) = 10c = 50F
[5] OAT = +20c = 68F
[6] Difference between ISA and OAT @2500 in F = 68-50 = 18F
[7] 10% for each 35F above ISA = 5.14% for 18F
Final Answer:
770 * 1.0514 +101.85 = 911 and 1455*1.0514 + 101.85 = 1631.6
911 and 1631 are nowhere close to 917 and 1637, am I missing something?
Cessna C-150. Calculate the takeoff ground run and total takeoff distance on a grass runway. QNE = 2500 ft; OAT = +20 °C; Headwind = 5 Kts; Max takeoff weight; Flaps up.
The answer is: 917 ft and 1637 ft
I calculated the Ground Roll and Total take off distance by interpolating:
[1] 910-630=280; 280 / 2=140; 630+140=770ft for Ground Roll
[2] 1660-1250=410; 410/2 = 205; 1250+205 = 1455 ft for Total Take off
[3] For a grass runway: 7% of 1455 = 101.85
[4] ISA Temperature at 2500ft = 15-2(2500/1000) = 10c = 50F
[5] OAT = +20c = 68F
[6] Difference between ISA and OAT @2500 in F = 68-50 = 18F
[7] 10% for each 35F above ISA = 5.14% for 18F
Final Answer:
770 * 1.0514 +101.85 = 911 and 1455*1.0514 + 101.85 = 1631.6
911 and 1631 are nowhere close to 917 and 1637, am I missing something?