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flutter
  • designing flight hardware
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  • Galil servo motion control
  • updating an established product line

Flutter Exciter Product

The Flutter Exciter was invented in 1987 and refined for decades since. My contributions have been minor by comparison, including adding the 250 in² size into the standard line, redesigning “Remote Mode”…

The Calspan Flutter Exciter product is a uniquely capable and proven system that supports the aircraft OEM’s and other customers while achieving their aircraft flight flutter clearance needs. The Calspan system excites the aircraft flight surfaces using a fixed vane with rotating slotted cylinder; as the cylinder rotates it deflects flow up and down and matches the aerodynamic effect of an oscillating trailing edge flap. The rotating cylinder architecture requires significantly less energy than oscillating flaps and is more controllable.

Many of the world’s airplane manufacturers, including Gulfstream, Bombardier, SAAB, Embraer, Cessna and KHI rely on the Calspan Flutter Exciter system to clear flutter and certify their new or modified aircraft.

link (2017-11-18)

Diagram of Flutter Exciter with rotating slotted cylinder

Illustration of Excitation by Rotating Slotted Cylinder, link (2017-12-09)


Photos

Diagram of Flutter Exciter with rotating slotted cylinder

Flutter Exciter Photos, link (2017-11-18)


Key Features

  • Higher frequency excitation than from hydraulics, stick raps, bonkers, or turbulence
  • Lower power requirements
  • No hydraulic plumbing
  • Symmetric or anti-symmetric excitation
  • Single frequency or linear/logarithmic sweeps
  • Force level can be changed in flight
  • (4) standard Exciter Vane sizes: 60 in², 90 in², 120 in² and 250 in²
  • Remote Mode generates consecutive user-defined excitation test points in close succession, maximizing data collection opportunities during an aircraft maneuver and saving test time


Where Used (Recently)

Photo of Gulfstream G700 with Exciters (https://www.gulfstreamnews.com/news/all-new-gulfstream-g700-makes-first-flight, 2020-02-17)

Gulfstream - G700

Photo of Stratolaunch Aircraft (http://www.stratolaunch.com/gallery.html, 2017-12-09)

Scaled Composites - Stratolaunch

Photo of E-2D (By U.S. Navy photo by Mass Communication Specialist 2nd Class Ernest R. Scott/Released - An E-2D Hawkeye flies over Naval Base Norfolk, Public Domain, https://commons.wikimedia.org/w/index.php?curid=31969349, 2017-12-09)

Northrop Grumman - E-2D

Photo of Gulfstream G600 (http://www.gulfstream.com/aircraft/gulfstream-g600, 2017-12-09)

Gulfstream - G600

Photo of Saab 2000 (By Bluescan sv.wiki - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=3455856, 2017-12-09)

Saab - 2000 modified

Photo of Northrop Grumman / Scaled Composites Model 400 (http://www.thedrive.com/the-war-zone/14551/these-are-the-best-images-yet-of-northrop-grummans-t-38-replacement-that-could-have-been, 2017-12-12)

Scaled Composites / Northrop Grumman

T-X (Model 400)

Photo of Gulfstream G500 (http://www.gulfstream.com/aircraft/gulfstream-g500, 2017-12-09)

Gulfstream - G500

Photo of Gulfstream G650 (http://www.gulfstream.com/aircraft/gulfstream-g650, 2017-12-09)

Gulfstream - G650


Articles

New All-Weather Flutter Exciter from Calspan

February 6, 2020

For flight test operators working against the clock to clear a flight envelope, an All Weather Flutter Exciter offers extra flexibility when facing rain, light clouds, or other ill-timed weather. Calspan has released a new line of All Weather Flutter Exciters, which perform just like the industry standard Exciters used in flight testing for decades, but with weather proofing upgrades and additional RTCA DO-160G qualification tests.

Our 60 in² All Weather Exciter passed multiple tests at Eurofins MET Laboratories, Inc. in Baltimore. It proved fully operable in water spray and partly operable in ice, with absolutely no compromise to safety and full recovery after melting.

Operators who would hangar an aircraft equipped with standard exciters to avoid an afternoon shower can relax with All Weather Exciters – saving you stress, schedule, and program cost.

All Weather Exciters are available new or as an upgrade to most standard exciters. Contact Calspan for more information to discover how you can complete your testing on time and on budget.

link (2020-02-21)


Gulfstream G500 completes flutter testing

February 5, 2016

Gulfstream Aerospace Corp. announced on February 3, 2016, that the Gulfstream G500 has completed flutter testing performed by test aircraft T1 over the course of more than 50 flights.

As T1 performed flutter testing, the second test article, T2, finished climatic chamber testing at McKinley Climatic Laboratory, Eglin Air Force Base, Florida, USA. The aircraft endured three days of hot testing, with temperatures reaching 131°F (55°C), followed by two days of cold testing as low as -40°F/-40°C.

Since T1 took its first flight on May 18, 2015, the aircraft has surpassed more than 320 flight hours. It has reached a maximum speed of Mach 0.999 and a maximum altitude of 53,000 ft (16,154m). T1’s longest flight to date lasted more than five hours. Additional test activities are continuing on track, including envelope expansion, air data system testing, aero performance, brakes and field performance, handling qualities and flight controls.

The second and third G500 flight-test aircraft, T2 and T3, both took their first flights on November 20, 2015. In addition to the climatic chamber testing, T2 is focusing on flight loads validation, along with aircraft performance and systems testing.

T3 is the primary testbed for the all-new Symmetry Flight Deck. T3 will also be used to evaluate ice-protection system performance, landing gear and nosewheel steering operation, environmental control system performance and the cabin pressure control system, as well as community noise testing. T3’s longest flight to date lasted more than six hours.

In addition to the three aircraft currently flying, the G500 flight test program will include two more aircraft. T4 has been inducted into the Flight Test facility and is in the final stages of flight preparation. P1 is a fully outfitted production aircraft that will test the interior elements as well as complete integration of the aircraft systems with the passenger experience.

The G500 is expected to receive type certification from the US Federal Aviation Administration and European Aviation Safety Agency in 2017. It is scheduled to enter service in 2018, with the G600 following in 2019.

link (2016-03-10)


World’s Fastest Civil Aircraft Gulfstream G650 Reaches Mach 0.995

August 29, 2010

By Mike Mitchell

Gulfstream Aerospace Corp. announced that its ultra-long-range, ultra-large-cabin Gulfstream G650 recently reached Mach 0.995 as part of its 1,800-hour flight-test program. Accomplishment establishes G650 as world’s fastest civil aircraft.

The aircraft achieved this speed during flutter testing, which evaluates the aircraft’s damping responses following an input from an external test device. Flutter testing is performed at a variety of frequencies, speeds, altitudes, weights and centers of gravity.

For the initial series of flutter tests, the aircraft achieved clearance out to both its design dive speed (Vd) and design Mach dive speed (Md) at altitudes ranging from 10,000 feet to up to the aircraft’s maximum certified altitude of 51,000 feet.

In order to achieve the maximum speed of Mach 0.995, Gulfstream experimental test pilots Tom Horne and Gary Freeman along with flight test engineer Bill Osborne took Serial Number (S/N) 6001 into a dive, pitching the aircraft’s nose 16 to 18 degrees below the horizon.

During the dive, flutter exciters introduced a range of vibration frequencies to the wing, tail and flight control surfaces to ensure the aircraft naturally dampened out the oscillations without further action from the pilots. Even under such extreme circumstances, the G650 performed flawlessly.

“The airplane is very predictable,” said Horne, senior experimental test pilot, Gulfstream. “It’s very easy to control and to get precise control at those speeds. The airplane response has matched the expectations of our engineers, and we’ve been able to easily fly the test conditions and march through the test plan.”

During the flutter test missions, a team of multi-disciplinary engineers in Gulfstream’s state-of-the-art telemetry center in Savannah monitored the aircraft’s behavior and determined real-time the damping characteristics of the aircraft.

The vibration frequencies exerted on the aircraft ranged from 2 hertz, or twice per second, to 58 hertz, or about as fast as a fluorescent light flickers. “We’re doing very well,” said Pres Henne, senior vice president of Programs, Engineering and Test, Gulfstream. “The demonstrated flutter margins met or exceeded our expectations out to maximum speeds. That’s a good sign.”

As S/N 6001 continued with flutter testing, S/N 6005 completed initial phase manufacturing and began engine testing. S/N 6005 is the fifth and final aircraft in the G650 flight-test program. Each aircraft in the program has a specific purpose, with S/N 6001 focused on envelope expansion, air data calibration, flutter, in-flight performance and flight controls.

S/N 6002 is used to evaluate the aircraft’s systems as well as its takeoff and landing performance, while S/N 6003 tests the avionics, in-flight load measurement and ice protection system. S/N 6004 will be the first G650 outfitted and tested with a full interior, which is currently being installed. S/N 6005 will participate in the reduced vertical separation minimum testing.

The G650 flight-test program officially began on Nov. 25, 2009. Through Aug. 25, the four airplanes currently flying in the program have completed more than 170 flights and 575 flight-test hours.

More: PDF (2017-12-02), link (2016-10-08)


In-flight Investigation of a Rotating Cylinder-Based Structural Excitation System for Flutter Testing

1993 June

By Lura Vernon

NASA Technical Memorandum 4512

More: PDF (2017-12-07), link (2017-12-07)