CKT523
Topic Author
Posts: 157
Joined: Sun May 09, 2004 2:56 am

Re: Tristar Early Birds

Wed Jun 02, 2004 11:48 pm

Hi, does anyone know why the engines on the L-1011 changed in appearance?If you look at the RB211 on early a/c the tail pipe part of the engine is quite long and tapered with sort of prongs coming out on the top and bottom of the pipe, looking not all that different to say a 767 engine, wheras,later models had a more stumpy cut off pipe similar to those on the 757 early models. Does anyone know why?
 
northstardc4m
Posts: 2724
Joined: Fri Apr 28, 2000 11:23 am

Re: Tristar Early Birds

Thu Jun 03, 2004 12:00 am

Early on, the RB.211-22 series had hot section reversers. After a few months in service it became apparent they werent needed and were removed to save on maintenance costs. This changed the profile of the engine somewhat by shortening the exhaust cone. This profile remaned the same thru the RB.211-524D and F models used on the 747-200/-300 and L1011-250.

Later RB.211-524G and H, along with the 535 series, models use a composite nacelle thats more aerodynamic. All RB.211 powered 747-400s, 767-300s along with most (some earlier ones have a 3rd cowl type) 535 powered 757s have the newer full length cowl instead of the shorter cowl seen on the earlier variants.
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broke
Posts: 1299
Joined: Wed Apr 24, 2002 8:04 pm

Re: Tristar Early Birds

Thu Jun 03, 2004 1:31 am

Actually, it took longer than a few months for the L-1011's to transition from the hot stream reverser to no hot stream reverser. The airplane went into service in April, 1972 and the change did not begin until late 1973.
It was a lot more complicated just getting rid of that portion of the reverser.
Most of the control features of the reverser system, both hot and cold stream, were tied into the hot stream reverser.
So much of the reverser control system had to be redesigned and then the whole system had to be recertified.
Problems with the hot stream reverser were not just a L-1011 problem; the 747 and the DC-10 also went through similar teething problems with hot stream reversers and, eventually, also got rid of them.
Today, no high by-pass powered airplane is equipped with a hot stream reverser; but the lesson was learned through the troubles of the early 1970's.
 
777236ER
Posts: 12213
Joined: Sat Aug 18, 2001 7:10 am

Re: Tristar Early Birds

Thu Jun 03, 2004 3:45 am

Later RB.211-524G and H, along with the 535 series, models use a composite nacelle thats more aerodynamic. All RB.211 powered 747-400s, 767-300s along with most (some earlier ones have a 3rd cowl type) 535 powered 757s have the newer full length cowl instead of the shorter cowl seen on the earlier variants.

535Cs that powered older RR 757s had the old cowl with the exposed hot exhaust. The updated 535E4 uses the longer cowl, with a mixer, a la 524G/H-T.
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