MBB-Rockwell X-31

PROJEKT Tkf-90 IN CRUCIAL PHASE
Tactical combat aircraft of the 90's

A new European combat aircraft project moves in the coming weeks into a crucial phase: In the summer 1979 the switches are to be placed for an international co-operation for the tactical combat aircraft of the 90's - *Tkf-90. we report on the conditions German pre-working and refer to our in the past years already published report in *FR 1/77 and 4/78.

Released by the combat effectiveness increase of air forces Warsaw Pact on the one hand and the at the beginning of the 90's lining up retirement from service of the Phantom combat aircraft F-4f and Rf-*ê an urgent need for a new tactical combat aircraft results in Central Europe. This combat aircraft should be suitable both and flexible component of the air defense and for the fight against ground targets (above all one had the air superiority roll with the *mehrzweck-Kampfflugzeug *MRCA Tornado according to Air Force inspector general *Obleser *bewusst *vernachlaessigt).

With increasing intensity run both in the Federal Ministry of Defense (project paper of aircraft *Rue IV 3) and in the Air Force operations staff (paper *Fue VI 4) and at the industry (working group MBB/VFW Fokker, in addition competing Dornier) pre-working for the *Tkf-90. In previously a not known close dialogue the test is undertaken, from the three basic conditions
* Budget/financial *Moegiichkeiten,
* Tasks and demands,
* technical possibilities
to come by a permanent coordination (Iterations *)Prozess to an optimum design.

At the three industrial companies Dornier, Messerschmitt Boelkow Messerschmitt-Boelkow-Blohm and VFW VFW-Fokker ran for some years in the context of the future technology programs (*ZTL) of the *BMVg preliminary investigations, and in the component trial program (*KEP) the *Vorbewertung of new technical components and the *Vorphasenentwicklung were introduced.

On the side of the German user, the Air Force, in a study group the operational, technical and industrial-economical aspects were arranged. The so-called position paper of the Air Force resulted from it is present in the meantime in the Federal Ministry of the defense (*BMVg). Afterwards to it then the tactical demands (*TAF) are to be compiled to center 1979. Although the conceptions of potential European partner countries lie still very much very apart, the *BMVg hopes that with France and Great Britain common, harmonized demands can be formulated, which follow the German demands to a large extent.

Main mission of the *Tkf-90 is the air superiority hunt against-flying targets at heights to approximately 50000 *ft. in all weather (the fight of very fast and highly flying targets, e.g. *MiG-25 belonged not to it, it will remain further task of the F-15 of the *USAFE). As of equal standing second roll the *Tkf-90 in addition, the mission are to be able to fulfill *Luftangriff ".

Mission *Luftverteidigung

For the air superiority hunt the *Tkf-90 is to have both over radar missiles of central range for the fight from the distance, and a outstanding turning speed, which ensures a superiority in turning-flight combat (*dogfight) in connection with infrared (IR *)Flugkoerpern and the not mounted gun interruptible by opponents. Great importance is attached beside it on a large *steigvermoegen, on sufficient speed, good launch with interior fuel, short radius of action and landing runs and - not least - to a progressive one-man cockpit.

With the avionics a relatively long-range on-board radar with TRACK while scan ability and look down, in addition a reliable identification system, *ECM (electronics *Counter *Measures)und *OCM (*Optical *Counter Measures) equipment and as conversion kit DATA LH for data communication with the *AWACS are to be essentially called.

Mission *Luftangriff

This roll should be possible without losses with the main mission air defense and serves the supplement of the two weapon systems alpha jet and *MRCA Tornado. The design of the *Tkf-90 must make therefore a high penetration speed possible at ground level, exhibit small gust sensitivity and make with supplementary containers large penetration depths possible. Most important components of the avionics for the air raid are a terrain avoidance system (in contrast to terrain *following with the Tornado), an efficient navigation system, radar and a *FLIR (forward *Looking *Infrared) for the homing and ECM/OCM systems. The armament might cover guided bombs, cluster bombs (modified *Mw-1), guided missiles, anti-radar guided missiles and conventional ballistic armament beside also the cannon required for the air-defense mission.

Out of the industry two competitive proposals for solution crystallized various pre-working, in order to fulfill the basis requirements described above. But only after being present the *TAF these suggestions of the industry on a definition of the weapon system *Tkf-90 can lead. Possibly it will come in the concept phase to a competition between the industrial's groups involved. In the following the different conceptions of the companies Dornier and MBB/VFW MBB/VFW-Fokker are outlined short.

Dornier

At Dornier one holds very expressly the point of view that only an cost-optimized design offers the possibility of being able to procure in the context of limited budgets also a sufficient quantity of combat aircraft. From pilot view naturally *bestmoegliche the aircraft one require, but because of the financial restriction one must less think more in the future substantially in *Flotten - and in Flugzeug combat capability. That is, that a larger quantity of economical aircraft represents a larger combat capability than few expensive.

Those today or in the near future being available new technologies wants to use Dornier therefore not unrestrictedly, but rather selectively. With the selection of the new technologies the criterion of the cost effectiveness is to stand in the first place (great importance has the choice of the engines in this connection!). A sufficient quantity in the sense of an optimal fleet combat capability can - as Dornier stresses - to be procured and used only if extreme demands and one-sided designs are avoided from the outset. No incompatible demands should be set up, neither be required unnecessary complexity nor exaggerated simplification and also no Sub optimization. From the outset the aircraft should be laid out after life cycle costs (*life *cycle *cost). All detail investigations are optimized at Dornier at expense.

The tendency to smaller, more economical combat aircraft sees Dornier not least confirmed by the decision of the Canadian government to only take the F-16 and *F-18 into the final selection for the future combat aircraft of the Canadian Air Force. The expensive, heavy types *F-14, F-15 and Tornado separated from cost reasons from the competition. There are even signs for the fact that the next generation of tactical combat aircraft will bring still more compact and more cost effective concepts than the F-16 in the USA.

In similar direction an expression of the inspector of the Air Force, general *Obleser can be interpreted, which had represented last yearly before the aviation press club the opinion in November, one may *von for the fascination of the future technology not roll over itself leave

However Dornier aims at with all project considerations from the beginning a design, which can profit also later still in the utilization phase from technical progress, not least, in order to be able to meet a possibly changing threat situation with justifiable expenditure. That means high development potential and flexibility e.g. by modular structure of the avionics.

In April 1978 Dornier of the Air Force and the *BMVg in a presentation had presented the conditions in this direction aiming and with considerable self financing portions of the accomplished studies. In the meantime in the close dialogue with the user the work was advanced in the *Vorphase. From the temporal operational sequence one has different conceptions than at at Dornier MBB one goes out clearly of the fact that the development program should be launched not too early, in order to be able to use still some years meaningfully for purposeful pre-working. Such a procedure would reduce the technical risk of the actual development substantially. The following development phase could be accomplished then however briskly, in order to keep the costs accordingly small. With a planned introduction schedule 1990/92 it would therefore be sufficient, if the common tactical demands of all partner countries end 1980/1980 of 1981 are present obligatorily.

Cost-effective organization
Also which concerns the execution and/or organization of the program for the *Tkf-90, Dornier develops other conceptions than MBB: As determining criterion the cost effectiveness is seen. In addition the following considerations are employed:
* On industry side a competent main contractor preferably faces the contracting authority.
* From political and psychological reasons the establishment of a controlling body could become necessary, which should be kept as small then as possible.
* In order to use the advantages of the industrial competition, the work up to the conclusion of the concept phase should be accomplished in the competition.
* Definition and flight test should take place in integrated teams.

General *Obleser gives *totalen, equivalent co-operation "as in the MRCA program however the larger chances. This way is to be aimed at despite the associated high expenditure. In addition, it stressed that the Air Force will keep out from all structure discussions.

Conventional design
Which concerns the general configuration of the *Tkf-90, then Dornier favors a conventional design with tail unit with reduced stability. Since 1975 from own resources and with promotion of the *BMVg examined Dornier lozenge wing concept (pointed in die to the *ILA 78) seems to be applicable only in the distant future - it is not included anyhow into the current TKF studies at Dornier. However test rows in down and high-speed wind tunnels had confirmed the expected decrease of the induced and the characteristic impedance and an increase of the maximum lift.

The examined wings of large span with large *Strakes ensure the extraordinarily large *manoevrierbarkeit and maneuverability wished for the *Tkf-90. The maximum stationary turning speeds at a height and a speed typical for the TKF missions lie more highly than stressed with the most modern US combat aircraft *F-1ã and *F-18l such as Dornier, bring in the aerial combat a turning speed higher around 2 degrees per second already a clear tactical advantage.

In the qualitative comparison with today's western combat aircraft Dornier believes not to be able to obtain a superior turning speed with to extreme thrust/weight ratio.

Mach 2 not necessarily
As maximum speed necessarily Mach 2 does not have to be aimed at according to Dornier, but design-determining a high accelerating power is in the *Transsonikbereich. From it a sufficient maximum speed results. For instance the division is sufficient Mach for 1.7, in order to be able successfully to fight the Soviet ground attack aircrafts (*Low level *Interdiction) *Su-19 and *MiG-23. The restriction within the high-speed division makes among other things fixed possible of engine intakes without adjustment mechanisms. If however for air raid missions the maximum demand should come to supersonic low-altitude flight (*Supersonic penetration) to the course, this would force according to Dornier opinion to one-changed, more complex design. Generally one can assume according to Dornier the *Tkf-90 for instance in the weight class of the *F-1ã lie will over-bid, but the performances of the *F-18l.

Engine selection still openly
The engine question is a substantial component for the cost effectiveness of the *Tkf-90, both which the number and which concerns the type of the engine. Dornier had examined, concentrates a single-engine design (*Tkf-90 *B1) from cost reasons first also the work however on a twin-engine version *Tkf-90b2. The choice of the type of engine is still open. Dornier tended to mission-fair and cost effective (speak simplified) discharges from existing engine samples and considers the *RB199 in the today's version (in the *MRCA Tornado) only conditioned suitably. Possibly from it however a version with reduced number can be derived from shafts and steps. The air intake should not be if possible because of the fuselage lower side, in order to have this division for the suspension point of guided weapons available.

Structure: more highly key-field-Kant-hurry
For the structure of the *Tkf-90 Dornier aims at a high portion (about 25 - 28%) of *KFK (carbon-fiber reinforced plastic). Pre-working for a KFK wing today already responsible at Dornier (in co-operation with MBB and VFW Fokker) are accomplished.

Great importance is attached to a cockpit most modern conception. Seat tilt optimal all-round visibility is to be ordered to the pilot with maximally 30 degrees, and the arrangement of the panels is to still exceed approved the high conditions of the *F-18 (depending upon state of the art to start of development). Additional expenditure for a two-seater would mean an additional expenditure of approximately 14% after Dornier calculations.

Most modern avionics
With the avionics Dornier sees the following centres of gravity:
* Integrated system with distributed intelligence,
* Digital signal processing,
* Multiple use of sensors and displays.
Which concerns the flight control and regulation, then Dornier wants to adapt in each case the flight characteristics to the different mission sections. In addition a trimable angle-of-incidence range up to over 60 degrees is planned. The control and maneuver surfaces are to be able to fulfill different functions (*Blended control, direct lift and component control), and particularly for the air raid roll a gust reduction system are planned.

A typical weapon load of 3 t (maximally 6 t) is to cover precision weapons, which promise high effectiveness also during relatively small disposable load beside the cannon and the surface weapons above all.

A mobile assembly of the cannon is not judged meaningful, since one can orientate the whole aircraft with the new control methods briefly, without changing the flight path.

No V/STOL ability
From a vertical take-off or at least holds one *does not landefaehigkeit for b i Dornier in connection with the *TKF much. However the launch and landing distances are to amount to only few hundred meters. The short take-off run arises as a result of also the high thrust/weight ratio anyway necessary for the application/mission missions and the good buoyancy coefficients of the wing. To the *verkuerzung of the landing distances the low approach speed (relatively small wing loading) contributes. In order to reduce the *rollstrecke at the ground, Dornier does not see small rolling speed large effect because of D it by a drag chute. On the other hand a thrust reversing system for costing and weight reasons separates. One favored therefore at present a space wheel braking (inclusive nose gear wheel), because because of the nose-heavy moment when braking can the straight nose gear wheel a large portion of brake energy install (a procedure, which is in former times already used with the ME 262 and today with Soviet combat aircraft).

Dornier maintains alpha of the jet program a continuous exchange of ideas on the basis over relevant key technologies with the partner company Dassault *Breguet and has since at the beginning of of 1978 a close co-operation with the company *Northrop, who developed independently very similar conceptions and approaches.

Dornier offers alternative
Dornier believes with these to the working group MBB/VFW Fokker competitive conceptional pre-working proposals for solution to have compiled in good time which offer important decision alternatives to the contracting authority and make a concretizing possible of the tactical demands.

MBB/VFW Fokker

Messerschmitt Boelkow Blohm is occupied in a *freiwilligen working group as well as a VFW Fokker project group with pre-working to the *TKF90. Contrary to Dornier one sees a chance only in the full exhaustion of all technological possibilities by research, science and technology of protecting the qualitative superiority of a weapon system in relation to the quantitative supremacy of the Warsaw Pact forces.

The objective of the qualitative demand, based on the expected threat toward end of the century must be it according to MBB opinion, the ratio application/mission expenditure to weapon success from at present 3:1 on 1:2 to thus improve in order the factor 6.

This target, also with consideration of the required bad weather combat effectiveness cannot be attained according to MBB/VFW opinion with a simple and cheap solution. Thus it concerns with the work on the project for the *Tkf-90 apart from the classical questions about aircraft size, number of engines, optimal wing loading etc. particularly the expenditure of modern technology.

The tendency for as large an application of new technological possibilities, as possible recognizable at MBB, seems to collide however with recent expressions general *Oblesers, according to those the possibilities of adjusting quantity by quality is covered already now. Further debited to the quantity on quality to position, become no longer fair the task fulfilment, and an idiom must be caused in favor of the quantity, without the quality may suffer thereby.

MBB favors delta canard
As one of the configurations possible for the *Tkf-90 MBB on the *ILA 78 presented a design, which represents a combination of *deltafluegel with canard tail unit. MBB *tkf is, at least in the basic version, single-seat and had two engines. Primary design goals at MBB are superior supersonic performances combined with outstanding maneuvering capabilities in the high subsonic region to down too much low speeds by eliminating, and/or extending the employing and sideslip angle delimitation. In detail MBB takes the following technologies for the *Tkf-90 in prospect.

In the area of aerodynamics the *delta-Fluegel are to ensure combined with artificial stability (*CCV) for superior *Transsonik and supersonic performances, the canard configuration make possible small trim moments with the penetration into the covered flight, and by direct booster control additional degrees of freedom of the aircraft price increase are to become possible. Together with *McDonnell Douglas accomplished *Simulationen of *unkonventioneller *Manoever in connection with new weapons, post office stable and direct booster control pointed out the large possibilities of these new maneuvers.

Which concerns the CCV technology, then from a *F-104 retrofitted in Manching on artificial stability to results which can be expected will surely have influence on *dasTKF-90. The effects of the CCV technology of these *F-104 seem to be however more from interest to than the way, how them were carried out thereby, because one still partly works at it with analog technique, while the *Tkf-90 is to be equipped with progressive digital technique.

Mach 2 and supersonic low-altitude flight
A maximum speed of Mach 2+ sees the company MBB with the current TKF design as attainable on (quasi as fall out of the actual TKF *Missionsforderungen, which presuppose a high thrust/weight ratio), and even the Supersonic penetration represents no extra large problem, since it concerns thereby only a brief maximum output over hostile area. For further distances in the supersonic low-altitude flight however are not those today admitted engines suitably.

Weight reduction by *KFK
During the airframe design MBB aims at weight reduction at optimal costs of basic structures by carbon fiber and GRP building method. With a KFK *Strukturgewichtsanteil of 41 a weight reduction could be obtained of approximately 18%.

A reliable uniform overall system both for flight control, flight control and avionics will become possible by a digital data processing system and a consistent use of microprocessors. Also the use of optical fibers for the data communication is examined.

Which concerns the drive, then MBB thinks of the adjustment *desRB-199 of the demands for air-to-air and of the assembly from thrust-vectoring nozzles to the production from control moments.

Does the mobile cannon come?
For the armament of the *Tkf-90 MBB suggests the development (possible with Great Britain) to a new active radar guided weapon with *fire and forget characteristics. For the air-to-surface roll improved avionics sensors are to be planned. In addition one is suggested for the *Tkf-90 optimized stand off armament.

A mobile assembly of the cannon is examined. In combination with supermaneuverability from it new combat potentials could result in the case of duels with several opponents. MBB does not underestimate the associated difficulties, and in the past obtained, outstanding success with fixed-Inge-built cannons are not to be surveyed likewise. But a combat aircraft with a turning speed of 18 degrees/seconds. (*F-1ã: approx.. 13 degree/seconds.) needs for a 90-Grad-Kurve five seconds, while e.g. ground or ship weapons can be orientated in only one second around 90 degrees to a target. If could succeed to solve this problem e.g. with a mobile cannon completely new aerial engagement possibilities would open.

V/STOL technology in discussion
vertical take-off *(VSTOL) MBB for the *Tkf-90 excludes abilities not completely. Some demands would cover themselves even with the TKF conceptions. The post office stable maneuvers e.g. require anyway additional control and stabilization possibilities, which come those from V/STOL aircraft already very close, so e.g. thrust-vector control and artificial stability.

An air intake suitable for angles of attack up to 90 degrees seems to be realizable. Thus MBB thinks of a *Tailsitter practically as fall out of the TKF demands. Horizontal short takeoffs are however the normal case. Modern control technologies make *Tailsitterstarts and landings today possible in relation to earlier tests quite. It remains natural pure speculation whether the V/STOL technology entrance into the *Tkf-90 will find. But in contrast to the situation, when the vertical take-off technology was in the *BMVg and at the Air Force completely taboo, this interesting possibility is included still a few years ago today again into the discussions with.

MBB does not see *unschliessbaren gaps in all suggested technological areas, since already theoretical and experimental programs were started. Substantially for the maximum performance gain of the *Tfk-90 the integration and optimal combination of these technologies are natural in a unit. This will have also influence on the relation of costs and performances, so that MBB is convinced of the fact that the *Tkf-90 will not be more expensive than a today's combat aircraft smaller *leistungsniveaus. While maintaining the today's *leistungsniveaus a cost reduction on 90% is possible. If one seeks to reach however the TKF *tKF-Leistungsniveau with conventional technology, this would mean a cost increase of 17,5%. A procurement of 705 performance-same aircraft in new technology corresponds to that with same budget with a procurement of 600 aircraft of the class *TKF in conventional technology.

*TKF within the Panavia framework?
For the organization of an international TKF program MBB for obvious reasons regards the structure of the Panavia GmbH as trailblazing, although one grants that one would have to modify the Panavia organization on the basis of the experiences made in the Tornado program.

VFW Fokker: TKF portion
Before the formation of the TKF working group with MBB VFW Fokker had compiled independent proposals for solution for the tactical combat aircraft *Tkf-90, and on the *ILA'78 in Hanover a wind tunnel model was publicly shown. VFW Fokker had suggested at that time a middle course between the *einfachen "Dornier conception and to substantially more complex MBB conceptions. In the meantime VFW Fokker with MBB represents the same direction within the TKF working group, held however still until recently an alternative solution ready (*fall bake").

Within the working group VFW Fokker processes primarily functional basic equipment systems (without armament), subsystems and application/mission equipment (optronic system, *Tv and infrared sensor, fire control system, radar) *Telezielerfassung, navigation systems) as well as structure investigations (KFK wing, KFK *Vollspante). The application/mission of new technologies with the *Tkf-90 VFW Fokker sees not so much under the criterion of the maximization of the performances, but more to the reduction of the costing and maintenance costs and the increase of the availability.

*Tkf-90: European program for the 90's

The next months will show whether and how after establishment of the German *TAF for the *Tkf-90 the conceptions of the potential partner countries France and Great Britain can be integrated into an international program. The German side seems to be convinced of it, the superior conception submits and the partners for it to join in to be able, certainly a high-put target.

Text: Peter *Pletschacher

http://forum.keypublishing.co.uk/showthread.php?t=49388&page=2

In West Germany, Dr. Wolfgang Herbst of Messerschmitt-Bolkow-Blohm (MBB) aggressively touted the advantages of post-stall technology (PST) for increased effectiveness during close-in air combat. Herbst’s conclusions were based on wind-tunnel tests of a German advanced canard fighter configuration known as the TKF-90 and piloted simulator studies during which the application of simulated thrust vectoring resulted in rapid directional turns at high angles of attack had increased the turn rate by over 30 percent. Technical discussions between the Rockwell SNAKE Program managers and Herbst were initiated in 1983, and planning for a mutual program on PST ensued. Discussions with the Defense Advanced Research Projects Agency (DARPA) were very positive. When funding for collaborative international activities became available from the U.S. (the Nunn-Quayle research and development initiative in 1986) and West German governments, the technical expertise of Rockwell and MBB were joined under DARPA sponsorship in the X-31 Program.

Ciders a écrit

N'oublions pas que le X-31 était une coopération entre les USA et la firme allemande DASA. Ce qui explique sans doute le delta.

rody1037 a écrit

la gueule du X-31 me fait penser à l'EF-2000