Hi Guys,
There is something I don't get right with Take-Off performance. I fly boeings but I guess it's same for every type. When we use Onboard Performance Tool, it gives us a longer ENGINE INOP GO DISTANCE, with FULL DERATE than DERATE AND ASSUMED TEMPERATURE
Here are some figures from OPT to illustrate:
Airport is RAK, RWY10, DRY, 0 WIND, 15°C, Q1015, Flaps 5, A/C AUTO, A/I OFF
FULL 24K 94.6% V1 138 VR 139 V2 146
R-24K 31°C 93.4% V1 140 VR 140 V2 146
Here is the thing I don't get:
24K MAX TAKE OFF POWER
Engine inop go distance 3051M
ASDR 2069M
all engine go distance 2027M
24K Assumed
Engine inop go distance 2165M
ASDR 2238M
all engine go distance 2210M
How come we need a longer distance engine inop go with FULL than ATM ?
thx for your help
Pilots.... !! Extra Information... Any how.
I tried the same experiment with on various fields (ATM/No Atm with and without Derate/No Derate).
Your reference to de-rate was not required.
>>In the case of ATM or FULL the V2 remains the same.
>>In ATM the v1 is higher
>>In FULL the v1 is Lower
In any case Vef (considered ) would be higher than v1 therefore in the case of ATM i would need lesser runway to accelerate from vef to v2 where as I would need more runway to accelerate from vef to v2 in FULL
ATM v2-v1 < FULL v2-v1
Also in the case of an ATM the speeds are based upon a higher density altitude there fore the actual performance achieved by the aircraft is better than that calculated