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The generalised chemical structure of polyisocyanurate showing the isocyanurate group. The polyols are abbreviated as R-groups.. Polyisocyanurate (/ ˌ p ɒ l ɪ ˌ aɪ s oʊ s aɪ ˈ æ nj ʊər eɪ t /), also referred to as PIR, polyol, or ISO, is a thermoset plastic [1] typically produced as a foam and used as rigid thermal insulation.
Rolls-Royce bought the Allison Engine Company in 1995, and has studied the Pratt & Whitney/Allison 578-DX propfan engine built in the 1980s. The engine has two contra-rotating rotors (fans) on the outside of the engine nacelle, either at the front of the assembly ("tractor") or at the rear ("pusher"). Both pusher and tractor open rotor designs ...
In high bypass engines, the fan is situated in a short duct near the front of the engine and typically has a convergent cold nozzle, with the tail of the duct forming a low pressure ratio nozzle that under normal conditions will choke creating supersonic flow patterns around the core [citation needed].
The Pratt & Whitney F119, company designation PW5000, is an afterburning turbofan engine developed by Pratt & Whitney for the Advanced Tactical Fighter (ATF) program, which resulted in the Lockheed Martin F-22 Raptor.
Diagram of a fan disk Fan disk assembly diagram, showing one blade and attachment hardware Cross section of fan disk Failed fan disk recovered from the center engine of UAL 232. A fan disk is the central hub of a fan in a turbofan engine. Fan blades are attached to the fan disk, which is rotated by a shaft driven by a gas turbine. [1]
The TF41 was jointly developed by Allison Engine Company and Rolls-Royce from the latter's RB.168-25R Spey. [1] Allison manufactured the TF41 under license, while Rolls-Royce supplied parts common to existing Speys. [2]
A propfan, also called an open rotor engine, open fan engine [1] [2] or unducted fan (as opposed to a ducted fan), is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop.
For the Boeing 777, the 84,000–98,000 lbf (370–440 kN), 112 in (2.8 m)-fan version development began in October 1990, achieved 100,000 lbf (440 kN) in May 1993, and was approved for 180min ETOPS at service entry in June 1995.The 777 launch engine, it entered service on 7 June 1995, with United Airlines. The 90,000 lbf (400 kN) PW4090 ...