Story ID: 609RollsPearl700
Rolls-Royce Unveils Pearl 700 Engine
By: Mark Huber
Caption: The new Rolls-Royce Pearl series engine will power the Gulfstream G700. 
Word Count: 603
Rolls-Royce unveiled the new Pearl 700 engine at NBAA-BACE 2019. The 18,250-pound-thrust engine will power the ultra-long-range Gulfstream G700. The Pearl 700 combines the company’s Advance2 engine core technology, a new low-pressure system, and various design and material changes to deliver 8 percent more takeoff thrust, a 12 percent better thrust to weight ratio (8 percent more thrust and 4 percent less weight), 3.5 percent less fuel burn, and 5 percent greater efficiency compared to the company’s BR725 engine on the current-production G650.

The new engine will meet or exceed Stage 5 noise standards and have nitrous oxide emissions that are projected to be 35 percent below the CAEP/6 standard. It is being developed at Rolls-Royce’s Center for Business Aviation Engines in Dahlewitz, Germany. 

The Pearl 700 features a 10-stage, high-pressure axial compressor; improved gearbox breather exhaust; new Safran-Aircelle nacelle; 24-blade, 51.8-inch blisked fan; bypass ratio in the 5:1 range; high-pressure compression ratio of 24:1 (compared to 16:1 on the BR725); six blisked stages; low-emission combustor; two-stage shroudless high-pressure turbine; and an enhanced four-stage low pressure turbine. The improved thrust comes from the larger fan combined with the more powerful core.

Significant weight savings come from the stronger and lighter nacelle, blisked fan, and the lighter, more powerful engine core. Compared with the BR725, the shape of the blades are different to optimize the fan to increase thrust, reduce noise, and limit resonance excitations to reduce fan flutter, according to Dirk Geisinger, chairman of Rolls-Royce Deutschland. He called the engine’s core “the most efficient in business aviation,” thanks to the blisks, new bearing cooling techniques, the increased use of composites including on the drive (tower) shaft, and advanced manufacturing techniques, including friction-stir welding.

The Pearl 700 uses the same nacelle line as that on the BR725 while accommodating a fan that is 1.8 inches larger. Geisinger said Rolls-Royce engineers were tackling 250 technical issues regarding changes between the BR725 and the Pearl 700. 

Other advanced technologies Rolls-Royce is looking at for the Pearl 700 include using 3D printing to manufacture ceramic tiles inside the combustor to limit heat and noise and ceramic nozzles to simplify manufacturing and reduce weight. “We’ve run these combustors already,” said Geisinger. "Now we have to decide whether they will enter into service with the G700 or later. It’s saving weight and making heat distribution more even.” 

The Pearl 700 is backed by the Rolls-Royce CorporateCare Enhanced hourly maintenance program and features a new engine health monitoring unit with advanced vibration monitoring, bidirectional communications, and the ability to remotely reconfigure engine-monitoring features from the ground. It feeds data into a system of cloud-based analytics, smart algorithms, and artificial intelligence.

Its health monitoring system detects all vibrations coming from the engines and identifies likely sources such as fuel pumps. Altogether, the system identifies more than 10,000 parameters, filters and livestreams data, and predicts to enable the timely replacement of line replaceable units. The engine will be maintained on condition with a goal of 10,000 hours before it has to be taken off-wing. Geisinger said the goal for the new engine is a 100 percent dispatch rate and that it was achievable with the engine’s new monitoring system. 

Rolls-Royce executive v-p for business aviation Scott Shannon said that adding vibration detection atop the traditional gas path monitoring of legacy health monitoring systems made this a realistic goal. “When your principal wants to go, he wants to go.” He said the hourly rates for CorporateCare Enhanced—which adds to CorporateCare by adding items such as nacelles and corrosion—on the Pearl 700 would be similar to those on the BR725.
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