777 Qs

[Macgyver]

I was doing some reading on the 777-200 vs the 777-300 and something didn't quite make sense.

According to the info, both aircraft have the RR Trent 892 engines (at least for CX' a/c); however, the thrust for the -200 was 84000lbs, while the -300 has 92000lbs. How can the thrust be different if the engines are the exact same?

Also, the same source quoted the -200's range as 7150nm, while the -300's range as only 5200nm. This doesn't seem right at all. Wouldnt the -300 have the higher range?

Thanks in advance.

[highalti2d]

If you ahven't already found the answer, the 300 is a longer version of the same aircraft, essentially. Therefore, it weighs more and with the same engine and the same wing, it is a little less efficient in range. The 200 ER and 300 ER are the same comparison. Don't know about the engines yet though, sorry

[highalti2d]

My info says it's a trent 877 on the 200 and a 892 on the 300.

[jtr]

As far as I am aware it is basically a manufacturer derate i.e. the flick of a switch. You get what you are willing to pay for.
Never driven the tripler so take my opinion with a grain of salt.

[Fly3]

As jtr says you don't have to use the full rated power if your operation never needs it. It is easy to select a lower rating ( basically a flick of a switch as stated) and therefore safe engine life and reduce maintenance costs.

[GlueBall]

The latest GE powered version of the -300 is in the 115,000lb thrust category.

B777-300ER with GE90-115B engines has 7900NM range

[singleseater]

Don't know about CX but for the EK a/c
The 220's have RR 877 at 77000 lbs. MTOW 242 t
The 200er's have RR 892 at 92000 lbs. MTOW 286 t
The 300's also have RR 892 at (yes , you guessed it) 92000 lbs MTOW 299 t
The 200er's and the 300's have the same fuel load, so the 300 has less range because of it's heavier wt. The 200'er's have the best power to wt ratio, the 300's the worst
The 300 er's have GE 115's at 115000 lbs
The 200 LR's will have GE 110's at 110000 lbs Exactly the same engine, in fact they are interchangable, it's just a data card change

[BuzzBox]

At CX the 777-200s have the Trent 877, rated at 77,000lb thrust, while the -300s have the Trent 892, rated at 84,000lb thrust. It's essentially the same engine with a different thrust rating. When CX bought the original -300s the engines were rated at 89,200lb thrust, but for certification/contractual reasons we weren't allowed to use the full rated thrust except in emergencies. Later on they 'de-rated' the CX engines so they'll only produce 84,000lb at Max TO. If they paid the dollars I guess they could bump it back up again to the full 89,200lb thrust rating, but for our operation we don't really need it.

The 777-300 was bought by CX as a regional aircraft for bouncing around Asia and was certified with a relatively low MTOW. At typical zero fuel weights, the -200 can uplift more fuel than the -300 before it hits MTOW. The -200 is also lighter, hence the longer range.

For the CX aircraft, the actual fuel capacity of the -300 is much greater than the -200 (137,500kg vs 94,300kg), but even on a ferry flight the most we could uplift in the -300 is about 108,000kg before we hit MTOW. The most we carry in the -300 under normal circumstances is about 50,000kg, usually much less.

[gas path]

The Trent powered Triples in BA's fleet are RR Trent 895. Usually the only time a full power takeoff is used, is the first takeoff following an engine change. With 'power by the hour' a full power takeoff costs money!:8

[Fil]

The actual fuel capacity of the -300 is much greater than the -200 (137,500kg vs 94,300kg),

In my company, we only have 200's, 94,300Kg refers to only 3 A Market of none ER 777's. All of the others, both GE and RR can carry 137,500Kg of fuel. But, the RR aircraft are rated for 297t, the GE either 267t or 275t depending on config. That said, typically the RR aircraft have the potential to carry more fuel for a given pax load.

At 297t out of SIN bound for LHR in the winter with Prestwick as a div due fog inthe south of the UK, the fuel load was around 113t....from AUH to MCT same aircraft it was as little as 11t.

Back on the thread a bit I always though the second two digit's on the Trents referred to the power rating, ie we have 895's....95K of thrust.