SIA choice of engines. Why ?
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Hi all,
I realise that SIA's choice of engines and the ones 'recommended' at Boeing's website are different.
Plane-----------------Boeing site------------SIA----------------Remarks
772-------------------Trent 877--------------Trent 884--------Higher
772ER----------------Trent 895--------------Trent 892--------Lower
773-------------------Trent 892--------------Trent 892--------Same
773ER----------------GE90-115B------------GE90-115B------Same
744-------------------PW4062----------------PW4056---------Lower
My questions are
1) Why is there no specific trend of more powerful engines or less powerful engines ? Why were some planes fitted with more powerful ones and some less powerful ones ?
2) The 773ER are to be fitted with GE engines. That is understandable as I believe the Trent 895 is the most powerful Trent 800 engine and its inadequate for the 773ER. Am I right ?
What I do not understand is why are the 744 not fitted with Rolls Royce RB211? Won't SIA save money by using as many engines as possible from the same maker ?
3) The 744 has a maximum takeoff weight of 397 000kg. The 773ER has a MTOW of 351 000kg. The 744 uses PW4056 and the 773ER uses GE90-115B.
56 x 4 = 224.
115 x 2 = 230.
Why does the heavier plane, 744, require less thrust ?
My guess is the requirement is for the remaining engines to be able to continue the takeoff even if one engine fails.
56 x 3 = 168.
168 > 115.
Is that the correct reason ?
And can someone tell me how to use columns when typing these posts. So i can not waste time with the ------------. -
Not too sure, but I fink it must be something to do with the economics of ordering large batches of engines and their corresponding parts. Since SIA has a VERY large fleet of B777s, using the same engine from the same manufacturer might save some money.
Also, the choice of engines might also depend on the fuel comsumption. Now fuel prices are so high
, thus a feul-efficient engine will make a more sensible choice than fuel-intensive engines. So if an engine with a lower thrust can still fly the plane, why use another more powerful engine that consumes more fuel per kilometer.
Just my two-hundredths of a dollar worth. -
A little off topic.
Good for my bonus about the GE engines. -
Originally posted by vyniker:
First and foremost.
[b]Hi all,
I realise that SIA's choice of engines and the ones 'recommended' at Boeing's website are different.
Plane-----------------Boeing site------------SIA----------------Remarks
772-------------------Trent 877--------------Trent 884--------Higher
772ER----------------Trent 895--------------Trent 892--------Lower
773-------------------Trent 892--------------Trent 892--------Same
773ER----------------GE90-115B------------GE90-115B------Same
744-------------------PW4062----------------PW4056---------Lower
- SIA does not have B777-200s. All of SIA's B777-200s are ER versions.
- That said, all of SIA's B777-200s come with Trent 892s. The regional 772s are then electronically downgraded to 84,000 lbs max thrust hence rendering them similar to Trent 884.
Lets just use the 772s as Eg. The takeoff weight for a regional 772 is usually much less than a long haul 772. With a lower take off weight they require less power, and thus, lower engine thrust.
My questions are
1) Why is there no specific trend of more powerful engines or less powerful engines ? Why were some planes fitted with more powerful ones and some less powerful ones ?
Yes, and also because of an exclusivity deal that GE has with Boeing to produce the GE90-115s.
2) The 773ER are to be fitted with GE engines. That is understandable as I believe the Trent 895 is the most powerful Trent 800 engine and its inadequate for the 773ER. Am I right ?
[qupte]
What I do not understand is why are the 744 not fitted with Rolls Royce RB211? Won't SIA save money by using as many engines as possible from the same maker ?[/quote]
No, why should it save money? IIRC there's an advantage in using the PW engines, think they are the most economical ones but cant confirm that.
A 777 requires enough thrust to take off on should 1 engine fail on to. If 1 engine on the 777 fails, there's only another to complete the to.
3) The 744 has a maximum takeoff weight of 397 000kg. The 773ER has a MTOW of 351 000kg. The 744 uses PW4056 and the 773ER uses GE90-115B.
56 x 4 = 224.
115 x 2 = 230.
Why does the heavier plane, 744, require less thrust ?
My guess is the requirement is for the remaining engines to be able to continue the takeoff even if one engine fails.
56 x 3 = 168.
168 > 115.
Is that the correct reason ?
On a 744, if one fails, you have another 3 to complete the work. -
When it comes to spare parts and maintenance, it can turn into a logistical nightmare.
