Flutter and ground effects

We’ve just achieved a further two important steps in the 787 flight test program – we completed flutter testing and ground effects testing.

Both of these accomplishments move us much closer to achieving Type Inspection Authorization (TIA) from the Federal Aviation Administration.

Flutter” is something you definitely do not want to happen in flight. It occurs when aerodynamic forces act on airplane structures and control surfaces causing a rapid, self-feeding motion that can be very destructive.

So, during flutter clearance testing we purposely introduce oscillations to verify that the airplane is not subject to flutter when operating within normal parameters. We verify it by demonstrating that even when an oscillation is introduced, the airplane will dampen the effect.

image/photo

ZA001 takes off from Boeing Field during flight test.

We tested at a variety of altitudes, speeds and fuel loads on ZA001. During the testing, we saw altitudes above 43,000 feet, dive speeds as high as Mach 0.97, and calibrated airspeeds as high as 405 knots.

The technical team has made an initial assessment of the data and we couldn’t be more pleased with the performance of the 787. The damping was as predicted and the pilots report that the airplane responded as expected.

Based on this data, the 787 test fleet has now been cleared to fly throughout its full flight envelope.

For the ground effects testing, conducted in Victorville, we looked at the aerodynamic effects on the airplane during low-altitude operations typically experienced during the takeoff and landing portions of a flight. This testing, conducted on ZA002, also went very well and matched our expectations.

Our test data is being turned over to the FAA as part of our Type Inspection Authority submittals. Upon validation by the FAA of this and other test items, we’ll see their technical teams join ours as we move into the next phase of this process – certification testing.

During certification testing - the longest of the four phases - we look at the extremes of the flight envelope including hot weather, cold weather, high altitude, over-speed conditions, hard landings and engine-out conditions. We also explore the details of performance from fuel burn to community noise.

There’s a lot left to do in flight test but no doubt we’re making great progress.

Comments (19)

Sunny (Sacramento, CA USA):

Good to hear that the Boeing 787 is making good progress. Can not wait to actually fly this guy...

RobH:

Congrats on the milestones. You've got one sexy airplane.

Edward N.Kaplanian (Mukilteo ,Washington):

Great news concerning the 787 test flights,I follow your journal on a regular basis.I knew from day one that the 787 will be a great airplane.

THIAGARAJAN (Kuala Lumpur, Malaysia):

Congratulations again Boeing

Dave (Lake Zurich, IL USA):

Great job everyone. This shows that the design guys have what it takes to predict the outcome before it happens. Lets keep this success going so I can finally book a flight somewhere and fly in one of these.

Kinbin (Taipei Taiwan):

I am comforted to note that the aircraft responded to flutter tests as planned, without an hiccups.

Unlike the current A380 beast from Brand X, which took to flutter not too nicely first time around and require rectification, the 787 has remained "slick* and *sharp* after first flight, besides the engine glitch.

Barun Majumdar (Seattle, WA, USA):

Nice explanation Randy on the phenomenon of fluttering. In fact, multi-disciplinary optimization to improve overall aerodynamic efficiency of an aircraft is the way to go!

Michelle (Everett, WA, USA):

After so many years of struggle on this program, it's quite gratifying to see such success. WE all knew it was going to be a great, beautiful plane. Now the rest of the world can see that, too.

Becky (San Antonio) (SA):

Randy's journal is a great source of information across the Boeing enterprise.

I doubt that many employee's across the globe every thought about what actually goes into flight testing a commercial airplane or otherwise, so this blog gives out the best of information and is greatly appreciated.

Nice work and look forward to reading the journal weekly.

Norman (Long Beach, California, United States):

Congrats on the flutter testing and prevention, I look forward to the successes made on the future certification tests.

Bill Hackensack NJ:

When the 787 had its very first flight, the President, ( Mr. Obama ) should have had a single press meeting lauding this achievement. Sticking out his chest with pride. As an example of what USA engineers and Boeing can do. What a missed opportunity.

I am not liberal or conservative. But if this was the Airbus, you would see the European leaders out there pounding their chests.

Barrie (North Vancouver, BC, Canada):

Fabulous explanations. I have been following the progress of the 787 from the first announcements and
can't wait for the opportunity to book a flight. Continued success to a great team.

Paolo Salvetti (Italy):

Great Guys, it is so nice to see B787 flight test progresses !!!!!
go go go

Captain Sensible (Frankfurt am Main, Germany):

Lufthansa -There's no better way to fly-

Keep up the good work guys!
Can’t wait to fly the 747-8 myself.

Richard Dumois (Orlando, FL):

Agree 100% with Bill Hackensack, that is because airbus is not really a 100% private company.
I do not understand why United has signed for the a350, and really hope Delta will keep NW order.
Congratulations Boeing

DAVID A CONLEY (ANACORTES, WASHINGTON):

When will the VMU & RTO Tests be performed?

Harrison Correia (São Paulo, Brazil.):

I am very happy about the testing of 787. I 737NG pilot and I am anxious to fly the DL. Congratulations to all the project.

Captain Eleven (Paris, France):

To Bill Hackensack :
Are you sure that a plane designed with french softwares (from Dassault) by people all around the world, built by italian, japanese, and everybody-but-almost-no-american-people is such an example of an american achievement ?
With a delay of 2,5 years, I'm not sure at all that it deserves a tribute from the president of the US.

Raja Daniel (Sydney):

Great to hear about Boeing 787 performance. I had experienced flying a few times in Airbus 380. I am looking forward in flying 787. cheers.

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