Boeing's pace towards 787 first flight continues to accelerate as the static test airframe has completed the third and final pre-flight test required for ZA001 to fly, Boeing confirms.On Tuesday, Boeing completed limit load testing which flexed the wings of ZY997 to a deflection of over 17 feet (120-130%), considerably exceeding the test requirement which only called for the wing to be flexed to 100% of limit loads a 787 would encounter in service, says a source familiar with the testing.
Boeing says the test flexed the wings to an equivalent of 2.5 times the force of gravity.
The previous two required tests included:
- 1G check out, which deflected the wings to nearly 10 feet, checking for interferences in the flight control surfaces and was completed on March 20, 2009.
Today's test was used to further check for possible interferences of the movable flight control surfaces of the wing as well.
ZY997 has spent nearly a year entangled in the blue metal frame of the static test rig in Building 40-23 as ZY997's structure has been systematically tortured to find the outer limits of the Dreamliner's structural strength.
Later in the certification campaign, Boeing will conduct the ultimate load test, bending the wings to one and a half times, or 150% of limit load, to satisfy FAA safety requirements.
Boeing has not yet decided if it plans to bend the wings to critical load, demonstrating the conditions that would destroy the wing, a force greater than 150% of limit load.
ALSO SEE: Here to there: 787 pre-first flight milestones explained
on April 22, 2009 12:39 AM | Reply
Looks like the moon and planets are aligning. I am just waiting for the stars to shine.
on April 22, 2009 3:09 AM | Reply
Some clarification: 120 to 130% of limit load would be equivalent to greater than THREE times the force of gravity, as limit load usually is 2,5g. Ultimate load is 150% of limit load or 3,75g then.
on April 22, 2009 4:46 AM | Reply
I agree with guru josh. 17/26 = 0.65. It appears that the wing was tested to 2/3 of ultimate load (which is limit load).
on April 22, 2009 12:09 PM | Reply
3.75 g (150% limit load) produces 26 ft wing deflection
2.5 g (100% limit load) produces 17 ft wing deflection
1.5 g (150% 1G load) produces 10 ft wing deflection
First flight @ 75% MTOW should thus produce about 5 ft of wing deflection. How's that for flexy?
on April 22, 2009 1:43 PM | Reply
Thanks WingedMigrator for clarifying that.
I guess that the report said that the deflection was >17 ft and the load was 120% to 130% of limit load. So it's possible that the report was purposely vague about the actual deflection, but still was accurate.
Also, earlier reports here said that the wing deflection was 10 ft for the 1g test. That has to be incorrect based on your numbers, and fundamental engineering (unless the 1g test was really a 1.5 g test).