Bernstein Research says ZA100 will be 8% overweight with a 10-15% shortfall in range.
Let’s take a look at what that might mean for aircraft performance:
- Boeing targeted a Spec Operating Empty Weight of 252,500 lbs for a 787-8 and maximum empty weight of 191,000 lbs at firm configuration, according to the Airbus assessment. 8% over puts the weight between 15,280 and 20,200 lbs over target.
- The figure of 20,200 lbs correlates closely to the Airbus Dossier, which cites 21,050 lbs of LN1 maximum empty weight growth since firm configuration. Airbus cited Boeing documents in this estimate. LN1 would be significantly heavier as a result of the significant instrumentation and associated wiring installed for the flight test campaign.
- Using this data (15-20K lbs) against the 1% SFC shortfall in Trent 1000
Build 4A[Package B] engines, the
PianoX performance analysis puts the 787-8 EIS range between 6,490 and 6,756 NM. (Up to 15% off of 7,650 NM) - However, Bernstein estimates the performance of the 787 “will translate into a range near 6,900 nm., well below the promised 7,700-8,200 nm. range.” (10% off off 7,700 NM and 15% off of 8,200 NM)
- Overall, using these various calculations, 787 range projections of overweight performance vary from 6,490 NM up to 6,900 NM.
- Great Circle Mapper comparison of 6,490 NM v. 6,900 NM v. 7,650 NM v 8,200 NM from Tokyo’s Narita Airport for rough range performance of launch customer ANA’s 787s.
ANALYSIS
Boeing has confirmed that it is actively seeking to reduce the weight of the 787.
The airframer has never publicly disclosed the actual amount of weight it needs to remove from the aircraft, though ILFC Chief Steven Udvar-Hazy, who has been closely involved in the aircraft design as one of the 787’s largest customers, says early aircraft will be overweight.
Airplane 20, which will be delivered to JAL, will be the first major production blockpoint incorporating significant empty weight savings and will see the max. takeoff weight grow to 227.9 tonnes.
According to documents dated April 2008 and obtained by rival Airbus, Boeing has already identified at least 1690 lbs of weight reduction for production aircraft, with up to 4000 lbs potentially available for elimination. If Boeing achieves an additional 4000 lb weight reduction, 787 performance would grow to just above 7,000 NM, per the PianoX assessment.
These weight overruns have the potential to be costly not only for ANA but for Boeing as well. For historical perspective, Boeing’s contractual arrangements with United Airlines promised the US carrier up to $500 per pound above contractual weight per year, per aircraft for the 777 program in 1995.
Using the available data from PianoX, analyst and competitor assessments, 787 entry into service performance is tracked between 6,490 and 6,900 NM.
Without aerodynamic data and route proving trials that can only be gained in the upcoming flight test program, many of these range estimates fall within a reasonable, albeit speculative, analysis.
Yet, the contribution of technologies such as trailing edge variable camber, raked blended winglets, drooping ailerons and spoilers, laminar flow optimized engine nacelles and additional engine performance improvements all leave open questions until real-world data can deliver a conclusive verdict on aircraft performance.
Boeing plans to conduct a final weighing of Airplane Seven once final assembly is completed later this year.
BOEING COMMENT
ATW – Boeing responds to skepticism, maintains 787 timeline – May 6, 2009
Regarding performance concerns, the company claimed the 787 will
“meet mission payload commitments to all customers.” However, it
conceded that “early airplanes are heavy and [we] are working hard on
implementing weight improvements.”Concerning the Bernstein
report, it said, “the conclusion on range is inaccurate and the 787-8’s
range is closer to 8,000 nm. than 7,000 nm.” Bernstein’s report said it
understood from customers and supplier discussions that the first
production 787s are likely to be roughly 8% overweight, with range
10%-15% less than promised, which translated into a range near 6,900
nm., well below the promised 7,700-8,200 nm. range.
This post was originally published to the internet between 2007 and 2012. Links, images, and embedded media from that era may no longer function as intended.
This post originally appeared at Flightglobal.com from 2007 to 2012.