seabosdca From United States of America, joined Sep 2007, 5385 posts, RR: 4
Reply 3, posted (9 months 1 week 4 days 14 hours ago) and read 3966 times:
Quoting StTim (Reply 2): Delta fly a 777 from JNB to ATL. It is a 17 hour plus flight mostly over water. It leaves early evening in Jo'burg.
That is a 777-200LR. A 777-300ER would not be able to make that flight without a stop.
Quoting 77west (Thread starter): I get a field limited MTOW of 154,577kg. With absolutely zero payload, it would only just make the flight.
Your field-limited MTOW seems wrong. Looking at the 767-300ER ACAPS (with high-thrust engines, which any JNB operator would have) it looks to me like on a warm day at JNB's altitude you should be able to lift over 170 t before hitting the tire speed limit. That would be more than enough to get you to LGW.
Edit: Looking more closely I think you need flaps 5, not flaps 15.
77west From New Zealand, joined Jun 2009, 125 posts, RR: 0
Reply 4, posted (9 months 1 week 4 days 10 hours ago) and read 3846 times:
I realized I was factoring in an obstacle incorrectly.
After re-doing the calculation, I get:
230 pax + bags = 22,310kg payload. Using an OEW of 90,011kg we get ZFW of 112,321kg.
According to calculations, fuel required is 70,300kg.
This results in a TOW of 182,321kg - within the MTOW of 186,880kg.
However - the system now says that at Flaps 5, Packs and Anti-Ice off, 22degC and 1020 pressure, with 9kt headwind component,
our field limited MTOW is now 171,192kg. This still implies that either my fuel calculations are wrong (probably) or that we
have to leave half the passengers behind, being 11,129kg overweight. 70 tons does seem like a fair bit of fuel for a 767. Flight is 5175nm (nominal).
I was just doing this to see roughly what the performance hit on a twin is from hot and high airports.