14 M forum December 2000

T W E N T Y Y E A R S AG O, on 20 November1980, the experimental aircraft CCV-F104Gtook off from Manching. It was the first take-off in a so-called E1-configuration, i.e. adestabilizing canard wing was mounted onto the fuselage behind the cockpit.

A modified F-104G Starfighter was used totest the CCV flight control system (ControlConfigured Vehicle). For the experimentalprogram natural stability was renounced.Parallel to the flight control system normallyinstalled in the F-104 series productionaircraft a newly developed digital "fly-by-wireflight control system assured an "artificialstabilization of the unstable test aircraft andthe appropriate and required flight propertiesof longitudinal and lateral movements. Theability to artificially stabilize unstableaircraft configurations was a prerequisite forthe design of a new military and commercialaircraft generation and is still considered tobe a key technology area. The technologyused for the CCV program was the startingpoint for the design and development of theflight control system for Eurofighter.

During the 45-minute test flight, CCV projectpilot Nils Meister was at the controls of themodified Starfighter. Although the mountingof destabilizing canard wings considerablychanged the aerodynamic characteristics ofa normal F-104G, the CCV flight control system ensured stable flight characteristics.

Dr Gerhard Loebert, former CCV program manager, explained in MBB-aktuell (a MBBnewsletter): "The goal of this flight was notto attain spectacular instability values as theaircraft remained within the neutral stable

CCV- F - 1 0 4 GA H I STO R I C A L CO R N E R STO N EThe first artificially stabilized aircraft flew 20 years ago

range. It was far more important to prove theefficiency of the CCV system and we managed to do so.

The performance of the CCV-F-104G teamwas honored this fall and the team wasawarded the Badge of Honor of the Gesell-schaft fr Luft- und Raumfahrt (DGLR;German Aviation and Space Association).The CCV program was a major milestone inthe conception and development of the Eurofighter.

Daniela Bommer

Picture above:The CCV program was tested in a F-104G

(Starfighter). In 1981 and 1982 the aircraftflew with its most unstable configuration:

canard control surfaces and tail ballast.

Picture beneath:Earlier test flights were done without the

canard control surfaces.

Programs Technologies Strategy and Goals History Miscellaneous

Mforum_engl_dez2000 07.05.2001 12:16 Uhr Seite 14

15M forum December 2000

Erwin Kunz, who today works in the MT6 division, was the CCV flight test manager atErding at the time.Mforum interviewed him about the program.

How long did you work for this program?

After approximately five months of familiarization I was appointed manager ofCCV testing in June 1977. We successfully completed the program in 1984 after 176 testflights. During this time we proved the functionality of the CCV system and all itscomponents, various CCV control versions forstable and unstable configurations, a back-upcontrol and a modern autopilot were success-fully developed and tested. And already atthat time we knew that our program was thecornerstone for a modern combat aircraft. Thefar-reaching consequences for the conceptionand development of the Eurofighter naturallyonly became apparent years later. We weredelighted that the DGLR has now honoredthis achievement.

What was the greatest challenge of this program?

Without any doubt the greatest challenge ofthe program was to develop a flight controlsystem for unstable aircraft configurationswithin the extremely narrow limits of a costand time frame and on the other hand tosafely demonstrate and prove the operative-ness and the efficiency by flight testing. Therewas not enough a/c model information available, therefore we had to derive the required data from test flights. Subsequently,another challenge was to recognize the risksof the development trials required by a com-pletely new flight guidance system concept.Accordingly, we had to define and plan thetest steps in such a way as to eliminate theprobability of catastrophic events occurring.

How did testing in the old days differ fromflight testing today?

It is extremely difficult to make a fair com-parison. First of all, Eurofighter the presenttest object, is not an in-house experimentalprogram, and secondly, 20 years ago it wasstill possible to act quickly and adequately inan individual, unbureaucratic way. In extremesituations we were still able to implement orrealize any necessary modification within acouple of days. As far as the testing was concerned, in those days it was possible to befar more efficient, because formalism was only applied where formalism was necessary.

In the case of traditional, aerodynamically stable aircraft, the ascending forceof the wings is induced behind the center of gravity. In order to equilibrate theresulting top-heaviness, a downward force must be generated at the horizontal tail unit.This reduces the ascending force and increases the aerody-namic total drag.

If the ascending point is in front of the point of gravity, the horizontal tail unitinduces the ascending force and the total drag decreases. However, theaircraft is no longer stable and must be actively controlled (CVV).

The CCV in its final configuration with ballast and canard wings.

ascending force

ascending force

ascending force

descending force

weight

weight

CO M PA R I S O N O F STA B L E A N D U N STA B L E CO N F I G U R AT I O N S

Programs Technologies Strategy and Goals History Miscellaneous

Mforum_engl_dez2000 07.05.2001 12:17 Uhr Seite 15