Dakotasport From Canada, joined Dec 2000, 228 posts, RR: 0 Posted (11 years 4 months 1 week 2 days 20 hours ago) and read 2178 times:
I was searching through the 'most popular' photos and came across an EAL 757-225 photo ID#564015 and I noticed the RR engines were similar in appearance to those on the L1011, 743 and was wondering why Boeing or RR went to the 'pop can' style cowl like those found on some of AA's fleet of 757s. I hope someone understands what I mean!!!
P.s. I like the older style engines myself, but are there any disadvantages to this design???
Panman From Trinidad and Tobago, joined Aug 1999, 790 posts, RR: 0
Reply 2, posted (11 years 4 months 1 week 2 days 19 hours ago) and read 2050 times:
What you are referring to is the common or integrated exhaust nozzle.
In earlier RB211's the cold stream (from the bypass airflow) mixed externally with the hot exhaust from the turbine exhaust nozzle.
In later models the cold stream and hot stream are mixed internally so to speak within the common exhaust nozzle.
This has the benefit that instead of having two airflows at different temperatures and speeds being exhausted into the surrounding atmosphere you now have one. This is a form of noise suppression - you only have the temperature/speed of the surrounding airflow and that of the exhausted gases. Only one shear layer to generate noise as opposed to two.
Viscount From Gibraltar, joined Dec 1999, 112 posts, RR: 0
Reply 4, posted (11 years 4 months 1 week 2 days 18 hours ago) and read 1928 times:
The difference in cowlings is between the RB211-535Cs that were fitted the early 757s, such as those delivered to Eastern and BA, and the subsequent and more powerful RB211-535E4s fitted to later models.
The only 757 at AV, N951PG with the 37,000 lbf RB211-535C engines operating at high altitude, high temperature airports such as BOG and RNG give us payload restrictions of almost 7000lbs less which does not occur with the rest of the fleet with RB 211-535E.