Robert E. Henderson

Chief of Advanced Propulsion Division of APPD

United States Air Force


            It's a distinct privilege and honor to have been invited to participate in this auspicious occasion - the 50th anniversary of one of the leading propulsion companies in the world today, and the 100th anniversary of propulsion technology development and acquisition in France .


            Today, I am here representing the propulsion community of the Department of Defense back in the United States , but more specifically I'm here representing one Dr. Donald Dicks. Dr. Dicks is a staff specialist for propulsion at the DOD.  Regrettably, he cannot be here today and asked that I provide the symposium with a brief overview of our premier propulsion technology development program affectionately called IHPTET.


            It's at this point, considering what has been presented thus far in the last day and a half, that some would say we are now moving from the sublime to the ridiculous.  I'm going to tell you about some technology advancements which if we are successful, and will become reality, will provide some very significantly enhanced capabilities in the propulsion systems of the future.


            IHPTET itself is an acronym.  It stands for "Integrated High Performance Turbine Engine Technology".


            If I could move back one slide.  I think I have gotten ahead by one.  Well, perhaps not.


            IHPTET itself is a very comprehensive and highly coordinated three-phase government and industry visionary initiative.  I'm sure some of you have heard that term - IHPTET.  It includes virtually all United States government and industry sponsored propulsion R&D devoted to advancing technology for military turbine engines.


            The goal of IHPTET is to develop and demonstrate technologies by the turn of the century or thereabouts, that when applied will literally double the performance and operational capability of the jet engine as we know it today.


            Now IHPTET was birthed, if you would, back in the mid-1980s.  It officially became a national program, a DOD NASA national program in about 1987.  The program itself got started because of a challenge that was put on the propulsion community back in the United States , and some of you may have heard about it. A number of people at congressional levels felt that turbine engine propulsion had reached its limits:  it was a sunset technology.  Those of us working in the R&D however, knew quite different.  And so we had to put together a program to convince Congress that
financially supporting further technology developments in this area would be very beneficial.  Not just to the military but to the civil side as well.  And, as a result, IHPTET was formed.


            The baseline capability for the jet engine back in 1985 is our reference.  You heard yesterday engines ranging in thrust-to-weight, for example for a fighter engine from 7-1/2 to 9 to 1.  So with that as a baseline, we were looking again at engines that could provide a capability in a 16 to 20 to 1 range, for say a fighter engine.  Consequently the IHPTET technologies themselves offer significant payoff when applied to virtually any propulsion system.  As a result, IHPTET is now the technology base for all future military systems in the US and will serve as the springboard for many new commercial engines in the future.


            Now referring to this chart.  Under IHPTET, there exists one overall government plan, and six individual industry technology development and demonstration plans, all of which are coordinated among the DOD military services in the Army, the Navy, the Air Force, as well as the advanced research projects office, sometimes referred to as ARPA, and the National Aeronautics and Space Administration or NASA.  As seen here, a special steering committee provides overall IHPTET guides.  That committee is chaired by Dr. Dicks.  I had the good fortune for about 6 years of serving as a secretariat to that organization which gave me the responsibility if you would of providing oversight and managing the overall activities of all the services and agencies plus industries that were part of the IHPTET program.


            The six US turbine engine companies you see listed there participate in IHPTET and form an industry planning panel that advises the steering committee on specific industry issues related to IHPTET.  In fact, I would point out that industry plays a very major role in IHPTET, financially as well.  About half the cost of the program over a 15-year period is borne by our US industries.  We're talking program that has been estimated to run between 5-1/2 and 6 billion dollars over a 15-year period.  The government will underwrite about half of that and the rest will come from industry.  I should also add that for industry to be what we would call a card-carrying member of IHPTET, they had to, for the first time, put together a technology development plan over a 15-year period, and as you know most companies today because of their concern about near-term issues and problems, don't think much beyond 3 to 4 years in any kind of detailed planning.  But this was accomplished.  That in itself was a major accomplishment, and we are working today against those plans that industry has put together.


            The plan that I mentioned in the beginning, that's a government plan, consolidates all the industry plans and highlights the more critical elements of that plan those technologies that have to be done, or their show-stopper type technologies.  And those are the technologies that are actually sponsored by the government as part of their contribution to the program.


            In addition to what you see here, there are seven complement panels in the middle of the chart - compressors, combusters, turbines, nozzles, controls, mechanical systems, and technology demonstrator engines.  And then beyond that, we even have four pervasive technology panels.  Panels that deal with materials, computational fluid dynamics, engine structures, and the most recent and newest one, cost reduction.  And these panels oversee the technology planning and development process in each of these areas.  Each panel has membership from each of the services and agencies that participate from the government and is chaired by a single individual representing one of those services.  Each IHPTET technology then is developed individually or jointly to the agreed-upon plan by one or more of the five IHPTET government organizations.  And I would also add that government does not develop the technology of IHPTET, they merely sponsor it.  It's the industry that does all the development and they do the testing of those technologies.  Semi-annual reviews are held by the steering committee to review the progress and problems of each technology area.  And that's one of the prime responsibilities I had twice a year as a secretariat.


            Shown here are the three basic phases of IHPTET.  These phases were created to provide milestones against which one could assess progress and, perhaps more importantly, to provide opportunities for transition of our technologies as they were being developed to current, upgrade, derivative, or  even new engines.


            A phase of IHPTET is considered complete when the goals are met during a technology demonstrator engine test, through one or more of our advanced development programs under IHPTET.  Through the achievement of these goals, IHPTET will provide the technology base then for future propulsion systems that are lower in cost, lighter weight and easier to maintain than today's systems, yet can fly faster, higher and with increased maneuverability.


            You will note that IHPTET also has broken into three basic engine classes, as if we don't have enough structure to it already.  But there are three basic engine classes we focus our R&D on.  The fanjet class, which is the large engine class, typically referred to as the fighter engine size class, if you would.  Also large transport engines, cargo and the like.  The shaft prop class which deals with rotary engines, helicopters engines and turboprop powered cargo aircraft.  And last but not least, the expendable, or missile engine class, which focuses on both tactical and strategic turbine engine-powered missile systems. Where possible, of course, technology developments are emphasized for broad applicability to one or more of these engine classes.


            Now, through this process IHPTET has successfully met the technology challenges of phase I and is now working on the critical path requirements of phase II.  As you can see, the fanjet class, on the left bar, has now met its goal for phase I, of 30% improvement in thrust-weight capability or in fact has demonstrated 13 to 1.  Both the shaftprop and expendable demo engines have in fact exceeded their phase I requirements and are well on their way to achieving phase II.  In a moment, I will highlight two key component technologies which were critical to the success of phase I and will enable us to achieve the next major milestone of phase II for the fanjet class.  I will focus specifically on that class today.


            IHPTET itself is a synergistic effect of many applied technologies.  It represents the development and application of advanced aero-thermodynamics and new material families, integrated with totally new and innovative structural designs.  The turbine engines tomorrow will be quite different structurally than today's engines, made possible by the development and application of such advanced materials as fiber-reinforced metal-matrix composites, applied then to highly efficient, advanced aerodynamic rotating components.  Some of these are operating at cycle temperatures approaching the stoichiometric temperature limits of our hydrocarbon fuels today.


            The basic technology development process and demonstration process for IHPTET is shown here.  I won't go into all of these in any detail, but just to give you a feel for how this activity evolves.  Component technology advancements across the top and middle of the chart are individually developed and assessed against their own assigned goals, and then those components are integrated into an experimental engine demonstration vehicle illustrated at the bottom-left from which the target IHPTET performance goal is then measured.  Once the engine demonstration goals have been attained, those technologies are considered ready for transition to propulsion system developments for ongoing or perhaps the future or new weapon systems.


            Phase I itself was specifically completed this past year with a technology demonstration engine test at Pratt & Whitney shown on the cover of the November 14, 1994 issue of Aviation Week.  The fanjet experimental engine that was operated by Pratt & Whitney in fact exceeded some of its phase goals and accumulated more than 150 hours of testing during that period.  Work towards the goal of phase II, which as you recall now is a 60% improvement over the baseline engine, is now well under way.


            Let me just take a moment then to briefly describe two of those key technologies I referred to a moment ago which were critical to the achievement of these phase goals.


            A key element of phase I was the development and application of swept aerodynamics in the fan rotor.  The principle here is similar to that of the swept leading edge of a fan or of a jet aircraft.  Early research indicated that by sweeping the leading edge of a compressor airfoil, as much as four-count improvement in component efficiency could be realized.  The swept aero simply reduces the delayed tip shock losses, resulting then in substantial improvement in overall rotor aerodynamic performance, offering in turn a resultant significant reductions in the fuel burn characteristics of the engine.  Hence range and/or perhaps payload potential of the weapon system can be substantially increased.  I said four-counts improvement in performance, adiabatic performance of the compressor, the compressor designers would give their right arm just for one count.  So this represented a major advancement in aerodynamic performance capability of that one component alone.


            This technology then can be applied in the more conventional attached-bladed disk design but performs even better yet in the integral blade and disk, or blisk design I believe you heard that term yesterday a couple of times. This key technology was successfully validated during phase I engine demonstrator testing and has in fact already been transitioned into a number of military and civil engine development efforts.  It's of that much importance.


            The benefits of several new IHPTET innovations critical to the achievement of our phase II goals can be seen in this chart.  The application of innovative designs and advanced high strength low density materials is really key to IHPTET's long-term success.  I mentioned three or four charts back that there are really two major elements that feed a third in this whole development process - advanced aero-thermodynamics and new materials.  Well in fact, the materials part of the equation if you would, is really key.  About 70% of the advancement that we can apply to realize this 2X goal will come from materials improvements.  These advancements offer for example, in this particular case with this compressor, potential to reduce a compressor rotor's weight by as much as 70%.  This is accomplished by a number of means.  One through the application of advanced materials themselves to advanced designs, aerodynamic designs, including the integral blade and disk rotors or the blisk, hollow airfoils, and even composite spacers and ring rotors, sometimes referred to as an integral blade and ring.

            The final compressor design on the far right, lower right, outlined there, is envisioned to be made entirely of advanced metal matrix composite materials and will be composed only of a ring type construction or 'bling'. Literally, the engine hub region is gone.  When compared to the more conventional compressor design using traditional nickel-based alloys in a full web and bore arrangement for each rotor as you see in the upper left configuration, the resulting four-stage compressor that you see here would weigh over 300 pounds or about 140 kg.  Whereas the blisk on the lower right, that design would weigh under 70 pounds.  A significant factor in the design of a phase II 16 to 1 thrust to weight machine.  The Allison Advance Development Company, now a subsidiary of Rolls-Royce back in Indianapolis , has been developing this technology and are now leading the field if you would in this new technology.


            Just by way of comparison, what you are looking at in the upper right corner is their four-stage metal-matrix composite ring rotor compressor.  That compressor would be compared to, say, a J79.  The J79 had 17 stages and produced a pressure ratio of about 12 to 1.  This compressor produces essentially the same pressure ratio in only four stages.  That's the advances in aerodynamics.  Quite frankly, I don't know the weight of the J79 but you're looking at a component there that is just around 100 pounds.  So there's a dramatic difference in terms of both performance and weight capability we are demonstrating here.


            The four-stage compressor you see in the upper right-hand corner has also been successfully completed, fabricated and core-engine tested at Allison to validate the basic bling rotor structural design itself.  Technology advancements such as this will make the 2X goal of IHPTET an ultimate reality.


            Just to summarize then.  You can see that the IHPTET program is an ambitious, a well-coordinated and today a very successful program with major advancements underway.  Phase I is now complete, representing a 30% improvement over our baseline engine, roughly 13 to 1 versus about 8 to 1.  And phase II component technology development towards achieving a 60% improvement is well under way.  Additionally, multi-use technology applicability to the civil, marine and industrial power engine communities is an important feature of IHPTET.  And lastly, IHPTET is considered by many today to be the development model for future propulsion technology planning.  Its basic process is literally getting worldwide attention today.


            This concludes my overview.  Again I wish to thank Snecma for inviting me to participate in this auspicious occasion.


            Mesdames, Messieurs, merci beaucoup.




 Copyright www.stratisc.org - 2005 - Conception - Bertrand Degoy, Alain De Neve, Joseph Henrotin