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Boeing 787 Dreamliner Reaches First Flight Milestone

Discussion in 'Off-topic Zone' started by adbutcher, Dec 17, 2009.

  1. adbutcher

    adbutcher K9NME

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    Boeing 787 Dreamliner Reaches First Flight Milestone
    Boeing's 787 Dreamliner's First Flight set for Tuesday, Dec. 15
    By John Loughmiller, contributing editor -- Design News, December 14, 2009

    To the outside world - and much of the aviation press - the Dreamliner storyline revolves around unmet delivery schedules, broken promises and a very embarrassing First Flight cancellation earlier this year.

    To the employees and managers involved in the actual creation of the airliner though, the storyline is different. It's about problems solved, objectives met and an incredibly long and detailed testing regime that culminates in the First Flight of Boeing's newest creation.

    Not since John Cashman piloted the Boeing 777 on its First Flight in June of 1994 has Boeing fielded such a complex new airliner. The 777 was Boeing's first Fly-By-Wire airliner which meant electrically controlled actuators, under the control of multiple computers, operated the flight surfaces.

    The 787 retains those characteristics and adds extensive use of composite structures to the mix. Seen in simplistic terms, the testing roadmap to First Flight appears straight forward. But the devil is in the details and the details for this extremely complex airplane are extensive.

    Legions of tests are performed on the individual parts and assemblies both in isolation and as sub-systems in preparation for integration.

    Eventually, all the parts and sub-systems are assembled into a finished airframe and additional extensive testing is performed. (It was during this rigorous testing regime that small portions of the wing disbonded last spring resulting in cancellation of the previously scheduled First Flight - much to Boeing's chagrin.)

    Finally, just before First Flight, the airplane is subjected to a systems integration test with an ominous name: "The Gauntlet."

    The Gauntlet is what stands between the preliminary tests and First Flight. During this phase, the aircraft is powered up and operating 24/7. Three shifts simulate all normal and abnormal ground and flight modes. Single and multiple failures are introduced and the designer's recovery procedures are verified.

    All of the design assumptions made over the several years prior to the creation of an actual airplane are either validated or they are refuted and changed. Sixteen test phases are utilized and each one consists of single spaced text printed on a stack of paper one inch or more tall.

    The detail is extreme. An example: every path and the reaction of every device associated with the tripping and resetting of every circuit breaker is analyzed. Nothing is signed off until all aspects of each event are understood and documented. Even if the engineering is understood and has a track record from tests performed on other aircraft, it has to be looked at again.

    The Gauntlet is a good name for the procedure.

    Finally, after a few days of high speed taxi tests, First Flight day arrives and the flight crew attends the pre-flight briefing. For months, the pilots have been working with the design and manufacturing engineers to sort out the details of the First Flight objectives.

    The general plan is to validate the basic design approach and to determine that the airplane has no bad habits.

    The airplane will be a flying telemetry platform. Designers and engineers will monitor the progress of the flight and be available for consultation should something unexpected occur. Afterwards, they'll pour over the data in excruciating detail, trying to dissect every bit of information.

    Take off speeds will have been generated by the designers and the cross wind, if there is one, must be well within the design parameters or the flight will be scrubbed. Once the aircraft rotates, the best rate of climb is established until a predetermined altitude is reached. From that point on, the airplane is kept within a block of airspace, by itself - with the exception of one or two chase aircraft - while the test objectives for the flight are ticked off one by one.

    Gentle turns are made in each direction as well as small pitch angle altitude changes. Bank angles for the First Flight will likely be limited to 30-45 degrees since extreme bank angles increase the wing loading dramatically. (As an example, at 60 degrees of bank, 2g are generated.)

    Power settings vs. fuel flow will be measured and compared to theoretical values. Power settings vs. airspeed will also be measured and compared to expectations.

    The landing gear will be cycled and the high lift devices will be deployed to check efficiency, pitch moments and effect on authority of the other flight control devices.

    The chase plane pilots will keep an eye on the aircraft and report anything suspicious to the Dreamliner's pilots. They will confirm landing gear operation, flap deployment, symmetry of flight control operation and keep an eye out for any hint of hydraulic or fuel leaks.

    Back in the cockpit, the pilots will determine if the instrumentation appears to be working correctly - something that will be thoroughly checked against the telemetry by the engineering test group.

    Finally, once the objectives have been accomplished, the airplane will depart its block of airspace and head back to Boeing Field. The approach and landing speeds it will use are specified by the designers for the aircraft's weight, weather and runway conditions.

    And after the taxi in and shutdown, everyone will receive high fives.

    For the media crowd, it's over, but for the employees and test pilots the testing goes on. Six prototype aircraft are involved in the testing and a full 24 hour day is used.

    Five hours each day are set aside for actual flight tests with the balance being used for maintenance and to make changes needed as a result of discoveries made in flight test.

    The objective is twofold: 1) to discover all problems before the first customer takes delivery of the airplane and 2) to reach the magic day when the Federal Aviation Administration gives Boeing its coveted permission to begin manufacture of the airliner.

    And when that day comes, the designers, pilots and test employees move on to another project. Somewhere along the way, they might pause for a moment to congratulate each other for what they've accomplished. Then it's back to work.
    John Loughmiller is an Electrical Engineer, Commercial Pilot, Flight Instructor and a Lead Safety Team Representative for the FAA.


    [IMG]

    The test roadmap leads from design to First Flight, but there are many stops along the way. Photo: John Loughmiller
  2. Aikmaniac

    Aikmaniac Well-Known Member

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    Thanks for the post! Really gives a perspective of what goes into test flights.
  3. adbutcher

    adbutcher K9NME

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    The amount of data that is being generated is sickening but necessary. In addition to flight test, production has its own inherit problems. However, despite all of the scrutiny from pundits that do not have a clue or all of the tags that will be generated by flight-test, it has still been one heck of a ride.:D
  4. big dog cowboy

    big dog cowboy THE BIG DOG Staff Member

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    AD - did you know the test pilot graduated from Wichita St.?

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