avec la participation de Stanley W. Kandebo

Senior Technical Editor Aviation Week




Jacques Vedel

Directeur des constructions aéronautiques

Président de séance


            Mesdames et Messieurs


            Comme Directeur des constructions aéronautiques, j'appartiens à la Délégation générale pour l'armement et, bien que non spécialiste des moteurs, je suis venu ici aujourd'hui pour essayer d'assurer la régulation de cette table ronde consacrée aux moteurs du XXIe siècle, aux moteurs futurs.

            Ces moteurs marqueront, nécessairement, un saut significatif de performances par rapport aux moteurs qui nous ont été présenté hier, je pense notamment aux moteurs militaires comme le F 119, le J 200, le F 404 ou le M 88. Les objectifs et plans d'actions pour les atteindre, dans chacun des trois pays que nous connaissons, vous ont été présentés successivement par Robert Anderson qui est Chief of Advanced Propulsion Division de l'armée de l'air américaine, par John Chisholm, qui est Chief Executive de la Defence Evaluation and Research Agency britannique, par Paul Kuentzmann qui est directeur scientifique de l'ONERA et par Stanley Kandebo, Senior Technical Editor d’Aviation Week.

            Nous commençons tout de suite de répondre aux nombreuses questions.



Robert Henderson

Chief of Advanced Propulsion Division of APPD

United States Air Force


            I have a lot of questions. They're all good questions and there's just no way we'll be able to go through them all. Perhaps some of you that have questions that I may not address, you can catch me on the side and I'll try to answer them for you at that time.

            Let me just take a few. One question : Do you think that the IHPTET research program is very effective relative to commercial engine technology ? The answer to that of course is 'yes'. The commercial side is an important part of our equation. Although the IHPTET program is dedicated to the military system needs, multi-use applicability of the technology is always being considered. In fact, industry would not be playing as large a financial role with us in IHPTET if they did not see the benefits that could be realized in their commercial market.

            Some examples of technologies that can and to some extent are currently finding their ways into the commercial market, is the swept aerodynamics; there are a number of civil engines that are now being considered for modification to incorporate swept aerodynamics in the first-stage fan; hollow airfoils, and as you've heard about even
yesterday, that's a part of our IHPTET activity ; brush seals, which is a new technology that's rapidly being developed and is finding its way into the commercial market ; eventually fiber-reinforced materials: it's gone far enough, I think that's definitely going to be coming. That'll be the new materials system of the future, and you're going to see a lot of that, both in military and civil applications.

            And of course a very heavy part of our IHPTET program is turbine cooling advancements as was mentioned by Dr. Chisholm. Turbine cooling is getting less and less in terms of the amount of air and you have to be able to more effectively apply the little air you have to cool the hot end of your engine. Under IHPTET, we're looking at advanced heat transfer design codes that can predict where to place the air, not just flood the whole airfoil with air and hope you hit the hot spot, but actually identifying to the external heat transfer work that was described by Dr. Chisholm – we have similar work going on in the States – and from that determine just where to apply that air flow.


            Another question : Is IHPTET a new Star Wars program, like SDI, or is it a program that we will see on new aircraft ? No, it's not an SDI-type program at all. Again, the program started back in 1987. It is a dedicated, long-term technology development and demonstration program. As I said, it involves both government and industry, it represents a commitment that quite frankly has been held together all these years by Dr. Dix. Without him at the helm, if you would, at the Pentagon I don't know quite where IHPTET would be today, but he's been able to maintain the funding requirements to support the program. And that leads into another part of this question : What are the funding for such a program ? As I mentioned, the total program was originally estimated to be around five and a half billion dollars over a 15-year period. The government is contributing about two and a half billion over that same timeframe and industry is picking up the balance. And that's still pretty close to what was projected. Obviously that can go up and down depending on inflationary costs and things of that nature, but that's generally what the program cost is.

            Now the Air Force is a prime government contributor ; about 70 % of the government's resources from the Department of Defense come from the Air Force per year, almost a hundred million dollars.


            Let's see, another question. Well, I'm not going to be able to answer this question directly but it does stimulate another question that goes along with it. The question was : Could you tell us what is the highest speed reached by the F-22 aircraft ? I don't know. I know it's got a super cruise capability, that means it can fly supersonic, but what the actual mach number is that they've actually flown to I don't really know. Relative to IHPTET though, that technology, for instance, one of the selling points is that if we were able to achieve a 20-to-1 thrust-to-weight capable engine, you could take that technology and put it into an aircraft that would have, say, a Mach 3 capability in an aircraft size about like an F-15. It would not be a huge airplane as one might think today. That's the kind of payoff that one could realize if that technology had applied to such a system.


            Here's an interesting question, and it's one that I didn't go into that relates to the new cost reduction panel, that's a new panel. I admit it was formed after I got out of IHPTET, so I don't know all the details and implications of that panel, but I know that its primary responsibility is to examine a lot of the new technologies that are being pursued by the various component areas from a cost-effectiveness standpoint in terms of acquisition costs that they might project, manufacturing costs, and even life cycle cost. In fact, you may not be aware but 20 to 40 % of the weapon system life cycle cost today is made up of the engine and fuel, so consequently any improvement we can make in terms of the engine's performance capability, i.e. getting to a 20-to-1 thrust-to-weight machine if you would, will substantially improve the life cycle cost picture of that weapon system. So that's a very important issue today.


            There's a question about, so there are some interesting advanced technology studies at present, and they refer to the magnetic, it says 'gear', I'm not familiar with 'magnetic gear', it's 'magnetic bearings' that I'm familiar with for engine shafts, and fluidic controls for the nozzle area. The question is : Do you believe these technologies will be integrated in the next generation of military engines or in a later generation ? Well interestingly enough, under Phase III the magnetic bearing is an integral part of that particular phase of activity, and there is some initial research being done right now in that regard. I've heard about the fluidic control aspects, especially with the nozzle area, but I don't know of any specific work going on right now that's being funded other than the IHPTET effort. Not to say that that might not also evolve in the future.

            Probably the biggest challenge in Phase III will be materials. As some of you may know, there is a program in the UK called ACME (Advanced Core Military Engine). That's very similar to IHPTET, it has very similar goals, it's not structured quite the same way but they're having the same problems and issues they're trying to deal with technically that we are under IHPTET, and we exchange views from time to time. And they view Phase III the same way: that materials is going to be the biggest challenge, it will probably force us definitely into some of the more exotic materials that we don't often feel comfortable with, like composites, ceramics, materials like that. We might be willing to accept that type of materials system for missile applications, non-man rated systems if you would, but to find those particular materials in a man-rated system makes a lot of people very uncomfortable. And there's a lot of work yet to be done if we're ever to realize any of those kind of materials.


            This is a question that I can't specifically answer, it's... but I can address a little bit. You may want to talk to Rolls-Royce to get a more specific answer. The question has to do with: How will you be managing the Allison role relative to Rolls-Royce's recent acquisition of that company and in terms of IHPTET ? IHPTET is a national program, it's not international as yet per se, and of course that's created a lot of consternation. As I mentioned, Allison is a subsidiary, really a stand-alone subsidiary of Rolls-Royce today. There is to be no migration if you would of technology from the subsidiary to the mother company, but of course we all know that in time that will definitely take place.

            On the other hand I would add that there is an element of IHPTET I didn't even mention, which is a structures part of IHPTET, one that involves a gas generator engine test of a number of these technologies from the various manufacturers. Interestingly enough, Rolls-Royce is one of the participating manufacturers. It's called the CAESAR program, another acronym, for Core And Engine Structural Assessment Research, C-A-E-S-A-R. But Rolls, Allison, General Electric and Pratt & Whitney are all planning to put some of their new technologies into a common gas generator for mutual assessment. So to some extent you might say the 'I', a second 'I' is about to be added to IHPTET, an IHPTET-'I' meaning IHPTET International, and I hear that every once in a while, so who knows? There may be a number of collaborative activities in the future even in this area.


            Well, there are a number of other questions, they're pretty scattered so... One question I'll just answer very quickly : What kind of plane or aircraft do you expect after the F-22. Its life has been reached, especially features of that engine. Well, of course, as you might expect, that's really difficult to say. Some say the F-22 will be the last, it's certainly going to be the last new engine to be developed in the US in this century and probably for many years to come the way our defense budgets have been reduced. But, there will be derivatives and upgrades of that engine. They are already talking about it. In fact, Phase I technology that I just talked about, some of that technology is already beginning to find its way into the F-22 engine. They are already either seriously considering or they are seriously applying it today, so IHPTET is already having an effect on that new engine as it's being developed.

            Relative to Phase II, it's difficult to say how much of that technology will be exploited, but it's definitely going to be considered very seriously, I'm sure. Thank you.



John A. R. Chisholm

Chief Executive Defence

Evaluation & Research Agency (Royaume-Uni)


            First of all I'd like to thank you all for your interest. Like Bob I've got danger in here of being buried in a blizzard of questions, but fortunately mine seem to fall into three categories, and if you don't mind that's the way I will answer them, and therefore I hope to catch up perhaps a bit of time on that.

            Firstly, I seem to attract some interest on the subject of funding. A number of you wanted to know what the size of our program was and how it compared to the US program. Well, the program that I was talking about, which is our research program, government-funded research program, which industry also contributes to, but the government contribution to that, annual contribution is 12 million pounds per annum. Now, the implication of asking how that compares to the US program which as Bob has just said is the IHPTET program, two and a half billion dollars over five years, it's kinda different, and if you ask me, "do I enjoy that ?", well, that's life. We've lived with it for some years and we still seem to be here, and it's not a fair comparison anyway because inevitably you're slightly comparing apples with pears - they don't exactly address the same thing.


            I'm asked to carry on from that thought to address the issue of research collaboration with France and with the USA. Well, the answer is we have research collaboration in both directions, we have a number of memoranda of understanding, for instance, between DRA and NASA, and also arrangements with Wright laboratories in the US, which we wouldn't both do if we didn't find it mutually attractive and beneficial to do those things.


            We also have collaborations with regard to colleagues here in France, which perhaps brings me on to my second area of questions, because a number of people asked me about the general subject of monofilament fibers, perhaps, particularly occasioned by the relationships that we have in the UK with Snecma on the Sigma fiber plant. Well, what can I tell you, we have a collaboration in place on monofilament fibers. It is a collaboration which sprung out of us taking up research which had been started by the British Petroleum Company, it's now a joint venture between DRA, Rolls-Royce and Snecma, and relates to a number of other programs which are funded both in the UK and France and by the European Union. Dr. Habibi particularly asked about that and I guess we'd be happy to provide longer answers than just these but it is based upon long fibers and powder, but the plant is still not in a mass production phase, it's in an early exploration phase where we are inevitably addressing the applicability and suitability of it for future programs.

            Moving on to my final set of questions, I'm asked here: Why did I put the 'E' in DRA to make it 'DERA' ? Well, the simple answer to that is that in the D-E-R-A's business, which runs to about one billion pounds a year, half of that is research and the other half of it is what we call evaluation, which is test ranges, major test facilities, undertaking evaluations on behalf of procurement customers and undertaking assessments on behalf of customers about future programs. So it is, if you like, providing confidence to customers that they are going to get what they want, and that they're getting what they want and they've got what they asked for.


            Right, moving on from that, somebody asked me, obviously interested by the amount of research work which we're asked to do in NOx these days, why so, given that motor cars produce at least a hundred times more. Well, of course that's true, but on the other hand airplanes fly a bit higher. And that clearly could influence the atmospheric chemistry in ways which we don't yet understand. So it's clearly a political issue, it's clearly an issue which excites the environmentalists and it's clearly one, if we want to make and sell airplanes in the future, that we've go to go on top of.


            My final question, which I've left to the end because, since I like to answer it, I'm asked whether we shall be collaborating in the UK more with the US or with France in the future. Well, a straightforward answer is : both. Thank you.



Paul Kuentzmann

Directeur scientifique de l’ONERA


            Le premier groupe de questions porte sur l’utilisation de nouveaux combustibles pour les moteurs aéronautique :

            Pensez-vous que le gaz naturel liquide ou l’hydrogène puisse remplacer le kérosène ? Menez-vous des recherches dans cette voie ?

            Quel est l’état des travaux sur l’emploi de nouveaux carburants en aéronautique civile et militaire ?


            C’est une idée ancienne qui est revenu à la mode récemment depuis que l’on a beaucoup plus de sensibilité aux problèmes d’environnement. Le kérosène, c’est à peu près deux atomes d’hydrogène pour une molécule de carbone alors que dans le méthane, qui constitue principalement le gaz naturel, vous avez quatre hydrogène pour un carbone. Evidemment dans l’hydrogène, vous n’avez que l’hydrogène. Cela veut dire que la combustion formera moins de CO2, moins de CO. Par contre, l’avion à hydrogène pose un certain nombre de problèmes d’isolation thermique qui ne peut être conservé liquide qu’en dessous de 20 K. Cela pose des problèmes de volume parce que l’hydrogène liquide a une densité très faible (007) alors que le kérosène a une densité très supérieure. Nous sommes également confrontés à des problèmes de sécurité car l’hydrogène est extrêmement fugace et ne demande qu’à s’enflammer.

            Je ne pense pas que ces problèmes soient déterminants. Ce qui est déterminant c’est que ça constituerait un bouleversement des avions -  des moteurs ont déjà marché avec ce type de combustible -  mais aussi un bouleversement aéroportuaire extrêmement important. Je ne pense pas que les compagnies aériennes soient prêtes à changer leurs avions et les aéroports changer leurs équipements en fonction de considérations quelque peu futuristes. Il me semble que cela ne viendra pas très vite à moins qu’il n’y ait un choc pétrolier important. Actuellement, il y a relativement peu de travaux sur ce sujet.


            La deuxième catégorie de questions porte sur le contrôle actif du jeu de turbines haute pression.

            Je ne pense pas qu’il y ait encore de procédé qui soit utilisé. J’ai présenté cela comme des perspectives qui pourraient apparaître si on voulait aller vers des moteurs très silencieux. D’un point de vue physique, ces systèmes seront comparables aux systèmes qui sont utilisés actuellement pour contrôler le bruit des cabines.


            Les deux autres questions portent sur les ordinateurs.

            Quels sont les besoins pour l’exécution des codes de calcul ?

            A quel niveau le supercalculateur est-il nécessaire ? Y en a-t-il un besoin pour de nouvelles générations et selon quels axes de technologie ?

            Il faut distinguer entre les besoins de la recherche et les besoins industriels. La recherche ne fait pas de calculs trop systématiques. Pour faire avancer les connaissances, elle peut utiliser quelques centaines d’heures de calcul d’un gros ordinateur.

            Pour les industriels, ce n’est pas la même chose. Ils ont besoin de faire beaucoup d’applications pour déterminer les conditions optimales. Ils ont besoin d’ordinateurs performants et économiques.

            Actuellement, on peut dire qu’au-delà d’une vingtaine d’heures d’un gros ordinateur il devient difficile à utiliser systématiquement. Il y a un réel besoin, au niveau des performances mais également du coût. On peut dire qu’un objectif raisonnable serait d’augmenter la capacité de calcul par dix.


            Y a t-il une confidentialité sur les codes de calcul ou est-ce une propriété internationale ?

            Je pense pas qu’ils soient une propriété internationale.

            Ces codes représentent des investissements considérables qui se chiffrent par des dizaines d’ingénieurs/an. Ce ne sont pas des choses que l’on peut se procurer facilement.

            Les codes développés sous financement DGA appartiennent à la DGA. Il en est de même pour l’ONERA qui sous tutelle de la DGA.


            Deux questions sur la coopération :

            Il semble que dans le programme IHTEP on assiste à une approche très pragmatique des problèmes par rapport aux solutions à base de simulation préconisées par la France. Ce découplage ne provoque t-il pas un désengagement des donneurs d’ordres français qui lancent des études trop théoriques et trop rarement transposées sur moteurs pour essais réels comme cela se fait dans IHTEP ?

            En fait, nous sommes un peu victimes de la façon dont nous avons préparé les exposés. Monsieur Henderson a focalisé sa présentation sur les choses extrêmement concrètes en montrant l’avancement du programme IHTEP mais je suis persuadé que derrière les produits qu’il nous a montré, il y a aussi des activités scientifiques qui ressemblent beaucoup à celles que j’ai présenté.

            J’ai fait la présentation inverse. Je n’ai pas présenté une partie des activités françaises parce que je ne savais pas si j’avais le droit de le faire. C’est tout ce qui concerne les développements exploratoires qui consistent à développer des objets et démontrer qu’ils marchent. Cela représente une grande partie des activités françaises.

            Le programme IHTEP et les programmes français représentent à peu près les mêmes caractéristiques. Toutefois, le programme IHTEP est parti depuis plus longtemps, il a donc des résultats plus spectaculaires aujourd’hui. Les développements actuellement en cours en France suivent une voie assez comparable avec un équilibre assez similaire entre les recherches de base et la technologie.


            Dans le cadre de la recherche de technologies nouvelles applicables aux moteurs d’avions, y a t-il des coopérations franco-américaines et/ou Europe/Etats-Unis ?

            Oui, il y en a beaucoup. Il existe un certain nombre de coopérations européennes. Par exemple des relations bilatérales entre les organismes de recherche, entre la DERA au Royaume-Uni et l’ONERA, entre la DLR en Allemagne et l’ONERA. Il y a également un groupe de recherche aéronautique qui comporte une composante moteurs et qui réunit des représentants des sept établissements de recherche européens et une participation des industriels. Il y a également tous les programmes de recherche de l’Union européenne auxquels tout le monde participe. Il existe également des relations qui dépassent l’Europe, dans le cadre de l’OTAN, avec l’AGARD qui comporte un panel qui s’appelle Propulsion Energetic Panel et qui traite ce genre de coopérations ou d’échange d’informations.

            Il existe également un certain nombre d’accords bilatéraux entre la France et les Etats-Unis : Data Exchange Agreement par exemple qui porte sur certaines technologies dont les turbomachines avancées.



Jacques Vedel


            Merci Messieurs pour toutes vos réponses. Je passe maintenant la parole à Stanley Kandebo.



Stanley W. Kandebo


            I think the presentations today have shown that there is quite a bit of work going on in both Europe and the United States, and I think that given the level of interest you can see that there is probably room for much more cooperation, perhaps between countries on each side of the Atlantic. As a journalist and as an engineer, sat here today, heard many of the questions focused on technical aspects, because we have technical experts. Many questions focused on funding, because people are curious as to what type of moneys are available and how difficult it is or is not to find them.


            I'd like to ask a general question about policy. Sitting here, it seems to me that from what I heard today, US emphasis has been more on military engines, it's more on performance, less on cost. European research, including that in France and in Britain, seems more to emphasize cost, seems more directly applicable to and oriented towards commercial engines. I'm curious, if each speaker could comment on these observations a bit, and on what their implications could be to the commercial manufacturers in their countries.



John A. R. Chisholm


            Well, perhaps I can kick off on that and... well it's true, because I would certainly claim to have emphasized in what I said that we see cost as incredibly important and an increasingly dominant theme. But we see cost as important not just in the commercial sphere, we also suffer from the fact that our Air Force does not have unlimited funds and that it seems to want to buy airplanes and aero-engines rather cheaper itself. So cost we see as a big driver simply to make projects feasible in the future. Clearly, they've got to have performance as well, and we have to achieve both in the future, but it's a question of balance.



Jacques Vedel


            Je remercie l’auditoire pour les nombreuses questions et les intervenants qui ont apporté de judicieuses précisions. Nous laissons maintenant la place à la séance suivante.




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