Failure is not an option – the inspiring legacy of a dreamer

I am a dreamer, believing that the mark of a champion is the ability to thrive in tough times. Gene Kranz, mission flight director, US Space Program

The quote above is part of the attitude that Gene Kranz tried to inspire in his young team of space flight controllers when they realized, confused, that the Apollo space program had came to an end.

Eugene “Gene” Kranz started in the Space Program with the early Mercury missions (first single manned capsules to reach orbit on a rocket), Gemini (earth orbital missions with crews and multiple modules) to the Apollo missions that reached the moon. He also took part in the Space Shuttle program.


Kranz on his flight director console at Mission Control Center (NASA)

For the general public, and maybe to youngest readers of this blog, he is most known for the portrayal by actor Ed Harris of his role during the Apollo 13 mission in the Hollywood blockbuster named after that mission. In fact, the celebrated quote “Failure is not an option”, that gives title to the book subject of this post, was never pronounced by Kranz himself, but just by his scripted character in the movie. An irony that he has always enjoyed.

Ed Harris as Gene Kranz

Actor Ed Harris as Gene Kranz in Apollo 13 movie (credit to Universal Pictures)

Alone with these ingredients, a book telling his story would make an interesting reading for lovers of aerospace and history. My opinion after having finished his book is that it goes way beyond that.

book cover Failure is not an option

Book cover (Simon & Schuster, publisher)

With almost 400pages, the book was written in 1999, coinciding with the celebration of the 30 years of the first landing on the Moon.

In the narration, from his early years as a young small-town engineering student and later air force pilot, to his career in the Space Program, he tells a compelling story about reinventing himself, about inspiring leadership and being a mentor of young engineers under enormous pressures, speaking of technical excellence and teambuilding to dealing with the end of the glorious days of the space era. I found there many lessons, some of which I want to share here.

But before that, a remark on three of the passages of the book that, for me, really stand out.

First, of course, the narration of the first Moon landing during the Apollo 11 mission, which he led as Flight Director. In this passage, about 10 pages long in the chapter “We copy you down, Eagle”, he shifts from writing in past tense as in the rest of the book to present tense, thus creating a thrilling and vibrant account of the very last minutes of that historical feat. A master trick that had me stuck to the book.

Second, the account of the entire Apollo 13 crisis, with the explosion in the oxygen tanks during the transfer trajectory to the Moon. This was the stage of the mission where his outstanding people management skills resulted in setting the Tiger Team that made history recovering the crew alive, and which is so well protrayed in the blockbuster movie I mentioned before.

Third and final, the reaction to the fire in the Apollo 1 capsule, in which the astronauts perished. This accident deeply shocked Gene and many program employees, rising the stakes in his understanding of the meaning of preparation and excellence.

The book shares a technical account of the precedures, vehicles and problems solved along the program, but also a myriad of personal anecdotes and landmarks. Terms such as The Brotherhood, or The Trench, were forged out from the hard work of entire teams and marked a decade of engineering mastery.

Even if somewhat out of context not having read the book, the paragraphs reproduced below, spread throughout the narration, provide a path of good lessons to reflect on. I grouped them according to aspects that I thought relevant and to be common to them. I invite the reader of the book to select other quotes as well and maybe give another interpretation.

Preparation and Training

They [the astronauts] would double- and triple-check what the controllers said and did. We had to earn their respect and trust. To do that we had to be smarter tan they were in each of our technical specialties, and we had to be utterly precise and timely in every action”  On the preparation needed to become a controller, especially during the Mercury missions, at the beginning of the Apollo program.

“It isn´t the equipment that wins the battles, it is the quality and the determination of the people fighting for a cause in which they believe” On the factors of success in bringing John Glenn safe during Mercury-Liberty 7 mission, where some retro-thrusters of the capsule were thought inoperative.

“Flight Control rappidly became the systems engineering cadre in the U.S. Space program” On the success of the same mission.

“My greatest fear approaching launch day was that I would lose one or more of my books. To assure that they were easy to find, I used pictures of various striking young women from the Sports Illustrated swimsuit edition for all my book covers and, if one were missing, this virtually guaranteed a prompt return” On the knowledge he wanted to have ready at hand, and the funny way to avoid it got lost.

“Aaron paused in the middle of an exchange with his support staff, stared at his displays, then made the decisive call, ‘Flight, have the crew take the SCE(*) to Aux'” Recalling John Aaron´s brilliant instruction,  out from his technical experience, which practically saved the Apollo 12 mission.

Limit situations

“We had a blind crewman outside the spacecraft feeling his way with his hands back to the cockpit. I thought, ‘ God, those guys are like icemen, chock-full of guts”’ On the troubled Extra Vehicular Activity (EVA) of Gene Cernan during Gemini 9A mission.

“I advice the controllers to take five [minutes]. The rush for the rest rooms (…) is the first indication of the pressure the controllers are feeling. (…) I do not want to look at my face in the mirror for fear that I might let my own feelings show” The moments after separation of the lunar module during Apollo 11, initiating the descent to the moon surface.

“While the world waits, Neil Armstrong sends goose bumps around the globe with the words: ‘Houston, Tranquility Base here. The Eagle has landed’.(…)  Frustrated at my lack of emotional control, I slam my forearm against the console.” Account of the extraordinary emotional state at the historical landing on the moon.

“My three leads will be Aldrich, Peter, and Aaron. Make sure everyone, and I mean everyone, knows the mandate I’m giving them. (…) John Aaron will develop the checklist strategy and has the spacecraft resources.(…) Whatever he says goes. He has absolute veto authority over any use of our consumables” Part of the address at Mission Control Center, announcing quickly a clear way to proceed in the face of the Apollo 13 crisis.

Apollo 1 Fire

“I wished there were some way to get in a judo match. I just wanted to feel some physical pain. The beer was not helping anything” Gene´s desolation feelings hours after losing the crew in the fire.

“I climbed the four steps to the stage, looking at all those faces of people I knew so well. I wanted them to get beyond shock, then say, as St. Peter did in on of his epistles, ‘ Let us get good and angry-and then let us make no mistakes”’ Kranz first address to his team of controllers after the loss of the crew.

“When you leave this meeting today you will go to your office and the first thing you will do there is to write ‘Tough and Competent’ on your blackboards. It will never be erased. Each day when you enter the room these words will remind you of the price paid by Grissom, White, and Chaffee. These words are the price of admission to the ranks of Mission Control” Final words of his address to the controllers after the fire, setting the Tough and Competent motto.

“We fought and won the race in space and listened to the cries of the Apollo 1 crew. With great resolve and personal anger, we picked up the pieces, pounded them together, and went on at the attack again. We were the ones in the trenches of space and with only the tools of leadership, trust, and teamwork, we contained the risks and made the conquest of space posible” His final words at the end of Apollo 17 mission, remembering the struggle after the fire of Apollo 1.

Comradeship and team building

“Carpenter´s words would often be remembered. At beer parties, or during debriefings, if we wanted to get John Llewellyn to tell the story of Aurora 7 and his first mission as RETRO, we would stand and say, ‘I didn´t know where I was and the didn´t, either'”  Funny recall of the discussion between RETRO controller John Llewellyn and astronaut Scott Carpenter during a troubled Aurora 7 EVA.

“One of my primary responsibilities was team building. I remembered a key method we used in the Air Force to Weld rugged individualists into a cohesive working group. A squadron insignia is used to give a group of fighter pilots a unique identity […] I discussed my concerns about the White Team´s training with Marta one evening (…) she said ´Gene, white is your team color-why don´t I make you a white vest to wear (…) you can used it as your team insignia” On the origin of his famed “white vest”, aimed at uniting his group of controllers of the White Team.

“Sheeet, man, that´s Captain Refsmmat, the ideal flight controller! He´s the best we´ve ever had in the Trench” Quoting John Llewellyn on the invention of a character based on the vital Reference of Stabel Member Matrix, or RefSMMat, a tool for orbit calculation.

“The debriefing party at the Hofbraugarten was merciless, beginning with a parody of the mission. (…) The parody began and ended with the ‘inmortal words’ Liebergot and I exchanged early in the crisis. Kranz: ‘I don’t understand that, Sy’  Liebergot: ‘I think we may have had an instrumentation problem, Flight'” On the fun they had remembering the early discussion when many data sent from Apollo 13 did not make sense to the controllers. It was clearly not instrumentation.

“I knew how they felt. When I won my wings, I believed I would fly fighters forever. When my dream ended, my world folded. So I had to pick myself up and get on with life, and find a new vision.(…) I am a dreamer, believing that the mark of a champion is the ability to thrive in tough times. I was convinced that Mission Control would evolve, adapt, and exploit every opportunity” Giving direction to confused young controllers as the Apollo program came to an end.

Praise and recognition

“To this day, John remains the most respected engineer ever to work in Mission Control. He was a superb mentor for younger, less experienced engineers” On the controller John Aaron. Along the book, Kranz doesn´t spare praise and recognition to the skills and achievements, no matter how big or small, of many people.

“The highly talented and resourceful women of the computing unit, Mary Shep Burton, Cathy Osgood, and Shirley Hunt, started out in Mercury with mechanical calculators (…) They provided is with options that just months before we did not know existed. We had no choice but ot believe in the data and methodology they came up with, so our trust in their work was aboslute. (…) Their work had to be perfect, and it was…” On the “human computers”, teams composed of women. These days remembered through the book and movie “Hidden Figures”.

Final comments

These excerpts are, of course, far from completely capturing the flair of the book, which is full of uncompromissed optimism, derived from the deep impact that President Kennedy´s challenge to put a man on the moon had on Gene Kranz. On it he shows true love and curiosity for the work of others, which was at the base of his teamwork skills. It is thus a gift for every engineer or person involved in a big endeavor with fellow ones.

Finally, I just can relate with this story. When I write these lines, it is almost eight years since I started working with Airbus, and in particular, some time later, in the A400M program. Not trying to compare it with the Space Program, of course, this endeavor shares some similarities in terms of big amounts of people involved through the years, the timescales and, to some extent, the kind of risk and complexity associated with flight operations. I saw many situations and personal anecdotes reflected in the text.

Moreover, it is also near two years ago that I changed my position to one as a technical manager almost in daily contact to the flight crews. The change happened to be just days before the fatal accident of one of our aircraft on May 9th 2015 that cost the lives of four crew members, our colleagues and friends, with two other surviving it. When I look back at those days, and I read the comments from Gene Kranz remembering his experience with the Apollo 1 fire, a shiver goes down my spine. Alone writing these lines is quite an emotional exercise that reminds me of the “Tough and Competent” motto mentioned above.

This post is thus the best way I could find to express how inspiring and personally resonating I found the values and experiences reflected in the narration of Gene Kranz. I invite every reader to let me know if I succeeded, but above all to be inspired by the narration of this dreamer.

Thanks “Geno”.

Gene Kranz foto

Gene Kranz (credit Smithsonian Institution)


(*) SCE refers to Signal Conditioning Equipment, a redundant power supply to the crew module. Switching it to its Auxiliary mode saved the mission from being aborted in the instants after the lift off.

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Irrational Exuberance – book review

I recently finished the book Irrational Exuberance, by Prof. Robert Shiller, in its second edition from 2005.

The exemplar was a christmas gift from my brother Javier, knowing the appreciation we both share for Prof.Shiller’s work and ideas, as expressed for instance in different posts in this blog.


Irrational Exuberance cover

Book cover

With 230 pages, the book provides both a quantitative and qualitative approach to stock and real state markets analysis of Prof. Shiller, largely relying on the principles of behavioral economics, a theoretical realm he has mentioned many times in his scholar and public work.

Reasonably understandable even with basic knowledge of economy, it is rather a reference book which provides a good framework to understand and to get an overview on how the mentioned markets behave.

The author builds on data gathered that go back to the XIX century and on his own research and results of the many surveys conducted by himself and other colleagues since the early 80s. The analysis and discussion are structured in four main parts:

  • Structural factors: where a series of precipitating factors (up to 12 different ones) and amplification mechanisms are analyzed which are the basis to explain the volatility of the markets, eventually leading to economic bubbles.
  • Cultural factors: discussion on the role of the media and news, as well as the economic thinking and “Zeitgeist” characterising the times of great volatility.
  • Psycological factors: introducing concepts of the behavioral economics such as anchoring, herd behavior and epidemics, that help understand individual and society decisions.
  • Rationalization attempts: where some economic theories dealing with markets behavior, such as the efficient markets theory, are discussed and challenged (*).

I found it a very good read, with the credibility of having anticipated the housing bubble of the late 2000s with this book (a confirmation bias argument as the author would put it). To bear in mind the aspects discussed in the book may help to keep cool heads even in times of economic turmoil and be better off for the future, even if we are told otherwise. As he puts it:

In an attempt to attract audiences, the news media try to present debate about issues on the public mind. This may mean creating a debate on topics that experts would not otherwise consider deserving of such discussion. The resulting media event may convey the impression that there are experts on all sides of the issue thereby suggesting a lack of expert agreement on the very issues that people are most confused about.

I thank my brother Javier for this good anchor in times of economic confussion.


(*) Prof. Shiller won the 2013 Nobel Memorial Prize in Economic Science for his analysis of asset prices, very much the subject of this book. He received the award jointly with other economists, in particular with Eugene Fama, one of the main proponents of the Efficient Markets Theory (EMT). It is famous his lecture for the Nobel ceremony, where he gracefully challenges Mr. Fama (watch it here, 33min video). In my opinion, a quote from this book (pg.193) puts that theory in good perspective: “Campbell and I (…) estimated that 27% of the anual return volatility of the U.S. stock market might be justified in terms of genuine information about future dividends (my note: the backbone of the EMT)”

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Keep donating to Wikipedia in 2017

“…sometimes it’s just about someone encouraging you to do the right thing”

This appeal from my former boss Manuel to donate to Wikipedia was a timely reminder of what has become a tradition for me, at least since I write in this blog: funding Wikipedia.

Last time I did it, in 2015, I wrote a follow up post summarizing the reasons why I donated. Read about these reasons here.

From those, I want to remark here again the value I give to having an ad-free service in my internet activity. With the unstoppable emergence of mobile browsing (thanks to more capable smartphones and tablets), the annoyance of pop-up and other kind of advertising banners has just risen from the levels I wrote about in 2015.

Of course, the fundamental reasons remain the same. Mainly the almost unlimited and quality documentary resources for my research.

Finally, a note about the recent reminder also sent by Wikipedia founder Jimmy Wales to past donors. There he tells that he received criticism for his past fundraising campaign. Well, he was not the only one to get criticism. In my previous post you will see a comment from a reader telling me that I was unaware of how inefficient Wikimedia is with the resource allocation coming from donations. I answered that maybe that was the case, inviting the reader to provide me with facts to support that and alternatives to be considered.

I am still waiting such response. Even if it was the case after all, I will in the meantime keep funding Wikipedia.

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Elegance in flight – book review


Elegance in flight: A comprehensive History of the F-16XL Experimental Prototype and its Role in the NASA Flight Research” is a release of 2014, written by Albert C. Piccirillo, of the NASA aeronautic ebook series. I read it right after the one devoted to the historic Round One  aircraft that broke the sound barrier (post here). This one discusses the many research programs that were carried out with an in-house platform conceived by General Dynamics (now Lockheed)


Cover of the ebook (credit to NASA)

In similar fashion to the ebook about the sonic boom mitigation research (see post here) this one is serves as a good reference and starting point to review the many research initiatives that benefited from this particular platform. Among them, the most relevant was the supersonic laminar flow control program, which I will comment below.

The inception of the F-16XL derived from an internal GD proposal for product enhancement during the 70s, in order to bid for future Air Force Contracts. The first chapters of the book discussed the technical drivers of this proposal and the conversations with Air Force.

In the following lines I will summarize the research highlights of this “commercial” effort, concentrated around the SCAM and DRF programs, and then the derived research on the platform with the involvement of NASA.

SCAM and DRF Programs

As mentioned, not long after the entry into service of the basic F-16 type, an in-house program called SCAMP, or Supersonic Cruise and Maneuver Prototype, was put in place to enhance the payload capability and to reduce the drag of the aircraft. The reason for that was that the aircraft was being operated in other missions than those originally intended, and was comparing bad with competing types.

General Dynamics paired with NASA in order to adapt the F-16 with a wing planform which was being considered for the general High-Speed Civil Transport efforts nation and industry wide (further info in the link to the sonic boom post mentioned above). The design was the cranked arrow wing.

F16 SCAMP configurations

Wing configurations matrix analyzed during SCAMP program (GD/Lockheed)


This design intended to combine the supersonic advantages of a delta swept-back wing (at around 70º), with the higher aspect ratio provided with the outer sections with less sweep angle (just 50º). In addition, the larger wing volume would result in increased fuel capacity and range than the production F-16.


“Cranked-arrow” wing layout (Wikipedia)


As the CFD studies and wind tunnel efforts evolved to find the optimal form, the Air Force joined in the support providing two basic aircraft for conversion. They were modified into the F-16XL-1 and F-16XL-2.

By then, the Air Force had issued a set of requirements under the Dual Role Fighter program, or DRF, and GD intended to bid for it. The competitor was the F-15 Eagle, and although the evaluation criteria were not uniform for the two aircraft, the F-16XL indeed showed two main flaws that ended the commercial effort: a low thrust-to-weight ratio and high induced drag due to the new wing planform. These two factors combined led to a loss of airspeed in “dog fight” maneuvering and ultimately to the loss of competitive edge against the F-15.

At the end of 1990, GD was left alone with the two test aircraft and no production contract in sight. NASA jumped in again. As commented in the post linked above, at that time HSCT program had evolved to High Speed Research and NASA saw the chance to use the F-16XL platform to investigate the benefits of supersonic laminar flow control.

Supersonic Laminar Flow

In aircraft aerodynamics, the laminar flow, where a fluid ideally flows in “parallel layers”, presents advantages in terms of minimal induced drag as opposed to the “turbulent flow” where the build up of such drag is higher. On aircraft airfoils, there is a transition from laminar to turbulent flow. The possibility to control this transition and minimize the turbulent flow is obviously worth the effort. The SLFC program from NASA aimed at that goal.

transition laminar turbulent flow

Schematic of boundary layer with its laminar flow and transition to turbulent


The next chapters of the book go on describing the CFD (computer fluid dynamics) studies and wind tunnel tests to define the wing modifications that would allow to test in flight two ways of achieving such a control of the flow: passive control and active control through “boundary layer” suction. The second one led to the so-called “suction glove” which was the landmark modification that gave fame to the F-16XL:

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In essence, the “glove” consisted of a set of wing skin panels covering the inboard part of the cranked wing, from the leading edge up to 70% of the chord.It was manufactured in titanium with micro-holes drilled with laser. These holes were grouped in clusters connected through a network of tubes inside the wing, and then to a compressor located in the fuselaje, that generated the suction. The controlled suction of the boundary layer delays the transition from laminar to turbulent flow. The mechanism for induced drag control was put in place.

The chapters devoted to the SLFC describe the validation in wind tunnel and in flight test of the structural and dynamic characteristics (flutter, handling qualities, …) of the modification. After all, it was a major change in the airframe and the aircraft had an asymmetric configuration of wing as a result of it.

The test results, in summary, confirmed the feasibility of this control and demonstrated a control of the laminar flow up to 50 to 60% of the chord (see schematic in the figure below). The chapter gives detail of the specific test points and configuration in which this flow control was most effective. It details also the many manufacturing issues of the glove.

F16XL laminar results

Schematic view of left wing leading edge with flight test results of laminar flow control (NASA)


However, in 1996 the program was terminated, as the  consensus within the team was that supersonic laminar flow control was not a near-term technology that could be available in time for integration into an HSCT program on any realistic cost and development schedule.


F-16XL-2 in flight, not the active suction glove in right side of the picture (NASA)


Further Research

In parallel to the activities associated to the SLFC research, such a unique platform gave incentive to use it for further flight test programs. The book describes in detail some of them in its chapter 10. These were the most relevant research topics covered:

· Vortex Flap. This activity involved the wind tunnel testing and modification definition of special leading edge flaps, called “vortex-flaps” aimed at reducing the higher induced drag typical from low aspect ratio wings. This effort was also in support of the general HSCT program, in order to reduce the thrust (an its associated noise) that was required to compensate for lower lift/high drag in low subsonic regimes. However, the modification was never implemented although the tooling was made available already at NASA Dryden Flight Test Center.

· Acoustic tests. The test flights of the F-16XL supported also the noise research related to jet engines and supersonic boom perception that were ongoing in the early 90s. With microphone arrays and sensors deployed on ground, different flight profiles in terms of speed and altitude were measured with this A/C. In addition, with pressure sensors located in the nose boom,  the F-16XL measured the SR-71’s near-field shock wave pattern flying as “chase aircraft”, in support of the High Speed Research program that was commented in the post related to the sonic boom linked above.

F16 SR71 sonic boom

F-16XL-1 flying “chase” to SR-71 measuring the near field sonic boom (NASA)

· CAWAP, or Cranked-Arrow Wing Aerodynamics Project. This was an international CFD validation program across industry and academia. It included, on the industry side, Lockheed, Boeing from US, EADS (now Airbus DS) Germany and turkish TAI; NASA and dutch equivalent NRL; and universities in the US, UK, Belgium and Sweden. The main objectives were to advance the “Technology Readiness Level” (TRL) of the current CFD codes, and to develop turbulence models for them that would ease the “agreement” among CFD, wind tunnel and flight test results.

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· Other efforts. The F-16XL served for other flight test purposes. For instance, the validation of an in-flight flutter (*) excitation tool. This was employed during the validation of the “suction glove” structural and aeroelastic characteristics. The aim was to have a controlled active excitation element in order to enhance the quality and repeatability of flutter and vibration data in flight. Other line of investigation was related to a new Digital Flight Control System, that would allow an expanded flight envelope for some vortex control flight testing. Although the code for the DFCS was prepared, finally it did not fly on the F-16XL.

Final notes

Although General Dynamics could not benefit commercially in the Dual Role Fighter contract from the historical wing modification to the otherwise successful F-16XL, the extensive flight research and the amounts of data gathered really paid off, and its research benefits last until today.

The basic research regarding laminar flow control expanded to the F-15B, which still flies today for NASA in support of supersonic programs (link here).

And the aerodynamic studies around the CAWAP are still discussed these days. In fact (and to add a personal note as in other book reviews) my company Airbus DS keeps involved as some of our colleagues participate in papers in that forum.

The many apendixes of the ebook provide extensive data on the test objectives, results and pilots for each flight, the Cooper-Harper qualitative assessment criteria for handling qualities (as commented in other reviews of this blog) or, a novelty in the NASA Series, the definition of the NASA Technology Readiness Level (NASA PDF here).

In summary, the F-16XL was not only an “elegant” design flying, it was one of the most successful and versatile flight test platforms, and this NASA ebook is a recommended guide and reference to understand the research around supersonic laminar flow control.

To finalise this post, find below an interview with Marta Bohn-Meyer, one of the leading engineers and pilots involved in the supersonic laminar flow control program, who is mentioned in the book. In the video, of 30 minutes, she discusses some technical aspects and flight testing status of this technology. Unfortunately she passed away due to a plane crash in 2005, so this mention may serve as a homage to her and to her role in this program, and in NASA in general, which was a very good example of the role of women in technology fields:



(*) Flutter: this term, mentioned in other post of this series, refers to a phenomenon in which the deflection of a surface (flap, aileron, …) provokes positive feedback from the airflow it is deflecting, in terms of aerodynamic force, thus exciting aeroelastic modes. This excitation can grow uncontrolled and result in catastrophic collapse of the structure and the complete aircraft. Thus the high importance of its study and minimization in new and fligh test aircraft.

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Probing the Sky – book review

“The Round One pilots – Air Force, Navy, NACA, Marine, or contractor- were the first to see the sky turn black and see Earth´s curvature, its hallmark as a planet”

Round One: A Reflection – Probing the Sky

Probing the Sky: Selected NACA research airplanes and their contributions to flight” by Curtis Peebles, is a 2015 release of the NASA Aeronautics ebook series, which has been subject to reviews in this blog. The book is devoted to the so called “Round One” formed by the first experimental research planes, the “X-Planes”, that explored the frontiers of supersonic flight between 1945 and 1958.

Ebook cover to Probing the Sky (NASA)

Ebook cover to Probing the Sky (NASA)

The release covers the main research achievements of seven aircraft in the early days of supersonic flight: Bell X-1, Douglas D-558-1 and D-558-2, Douglas X-3 Stilleto, Northrop X-4, Bell X-5 and Convair XF-92A. Starting with the X-1 and the conquer of the sound barrier with Chuck Yeager at the controls, these aircraft explored the characteristics of the transonic and supersonic flight. The book deals mainly with flight mechanics problems, such as stability and control as well as different wing configurations: swept and delta wings, variable geometry and tailless aircraft. Some passages use quite technical jargon, especially those related to flight stability, a fact that marks the entire ebook series, as has been commented in this blog before.

The historical review also provides a glimpse on the transformation of the NACA research institution into today´s NASA, and the consolidation of the Muroc Field as the Flight Test site that is today home to NASA Armstrong center (former Dryden Flight Test Center) within the Edwards Air Force Base.

Below I share a summary of the paragraphs from the book that highlight what was relevant about each of these historic aircraft:

  • Bell X-1 (1946-1958)

This aircraft was born from a years-long discussion among Armed Air Forces, NACA, Bell and Douglas about the configuration and objectives to be tested in order to reach the Mach 1 mark. As the book puts it “There were many design ideas about how a supersonic airplane should be configured.”  In fact, out of the discussion, other two types were created, which are commented later in the book, the Douglas D-558.

As for the Bell X-1, a design with straight wings, it would fly powered by the famous XLR-11 rocket engine from Reaction Motors, after being released from a B-29 mothership and glided to a secure distance before firing the engine.

Finally, on October 14th 1947, Chuck Yeager, still recovering from two broken ribs after having fallen from a horse days before, made history:

“Yeager leveled out at approximately 42,000 feet and fired a third rocket cylinder. The XS-1 accelerated rapidly to an indicated airspeed of Mach 0.98. The Machmeter needle fluctuated and jumped off scale.(…) Yeager held the speed for 20 seconds before shutting off the engine. Yeager radioed, “Ridley! Make another note. There’s something wrong with this Machmeter. It’s gone screwy!” Ridley replied, “If it is, we’ll fix it. Personally, I think you’re seeing things.”82 NACA personnel analyzed the flight data and determined that the XS-1 had reached a speed of Mach 1.06.”

The barrier had been overcome. Still, there was a lot of work for the next decade:

” There remained an interrelated series of problems in aerodynamics, propulsion, and aircraft configurations to bedevil and bother the aeronautical community in the years ahead. Nevertheless, if there were many challenges and unknowns ahead, there was one major bedrock accomplishment: the myth of an impenetrable barrier had been forever vanquished.”


Bell XS-1 in flight (NASA-public domain)


  • Douglas D-558-1 Skystreak (1945-1953)

“With a largely similar configuration to the more famous XS-1, this aircraft complemented the results achieved with the X-1. The rocket-powered X-1 provided data at speeds above Mach 1, and the jet-powered D-558-1 covered the high transonic speed range. As a result, the X-1 did not have to make low-speed flights; this accelerated the overall collection of data. Additionally, this aircraft was the first to test vortex generators, which improved wing aerodynamics at transonic speed and became standard on jet aircraft.

Douglas D-558-1 (NASA)

Douglas D-558-1 (NASA)

  • Douglas D-558-2 Skyrocket (1948-1956)

“Research with this pioneering swept-wing aircraft showed how to avoid the stability problems inherent in these wings, in particular that the horizontal stabilizers should be mounted low on the fuselage. When this aircraft was being designed, all operational U.S. and British jet aircraft had straight wings. Swept wings introduced the potential for much higher performance. The D-558-2 was also used in external stores testing, which allowed combat aircraft to fly at high speeds while carrying streamlined weapons and fuel tanks. Information derived from the D-558-2 program made all swept-wing aircraft that came after it safer and certainly more controllable.”

Douglas D-559-2 (NASA)

Douglas D-559-2 (NASA)

  • Douglas X-3 Stiletto (1952-1956)

“In terms of performance, this was the biggest disappointment among the early X-planes. It never came close to reaching its design speed of Mach 2 due to its underpowered jet engines. But it did show that low-aspect-ratio wings were practical, and such wings were subsequently used on aircraft such as the F-104, F-5/T-38, and X-15. The X-3’s most valuable contribution was to reveal inertial coupling to be anything but theoretical. The fully instrumented X-3 greatly enhanced the NACA’s understanding of the phenomenon and was passed to industry as well.”

X-3 Stiletto (NASA)

X-3 Stiletto (NASA)

  • Northrop X-4 Bantam (1948-1953)

“The semi-tailless swept wing was the only configuration tested in the 1950s that proved impractical. It would be another three decades before computer fly-by-wire systems would make the semi-tailless swept-wing configuration a workable reality, in the first generation of stealth aircraft and in many other aircraft and remotely piloted systems that have followed.”

Northrop X-4 (NASA)

Northrop X-4 (NASA)

  • Bell X-5 (1951-1958)

“The aircraft pioneered variable-sweep wings, but at a terrible price. While its wing pivot concept was impractical, it did validate the concept of variable sweep, encouraging further development that spawned the fixed outboard pivot point, used on subsequent aircraft such as the F-111, MiG-23, B-1, F-14, and Tu-160.”

Bell X-5 (NASA)

Bell X-5 (NASA)

  • Convair XF-92S  (1948-1953)

“This accidental research airplane had more than its share of poor flying characteristics, control system flaws, design shortcomings, and engine deficiencies. Unloved by its pilots, it nevertheless demonstrated the value of the delta-wing configuration, which became one of the iconic planforms of the supersonic—and indeed hypersonic—era. The XF-92A directly led to a notable family of delta successors, and from this sprang as well (though not solely because of it) Richard Whitcomb’s concept of area ruling.

Convair XF-92A (NASA)

Convair XF-92A (NASA)

Final notes

Each chapter discusses the technical problems that each type dealt with. These efforts, globally observed, helped the progress of aeronautics. However, not only it was not easy. These efforts were not free from criticism. In fact, one of the most respected engineers of aviation history, often cited in these reviews, Lockheed´s Clarence “Kelly” Johnson reportedly “dismissed the X-planes as drawing resources and technical effort that could best be focused on the development of practical aircraft designs.”

As I mentioned at the beginning, another interesting aspect that is made evident throughout the book is the evolution of NACA into NASA, and also of its main aircraft test facility. It started with the establishment of a NACA Flight Test Unit at Muroc Army Air Field around 1947.  With the pass of time, both the Air Field and its inhabitants evolved. From the Army Air Forces the Air Force was created, and Muroc Army Air Field changed to Edwards Air Force Base. NACA became NASA and the Flight Test Unit went through High Speed Research Center, to Dryden to current Armstrong Research Center.

The book is then a recommended reading for aviation enthusiasts with interest in history and the early years of supersonic aviation. The Round One aircraft ushered a new era in the conquest of the skies, in which the Round Two, with the incredible X-15 at its front, would take the lead.


Posted in Aerospace, Books, Technology | Tagged , , , , , , , , | 1 Comment

Sevilla Marathon 2017

“Don´t ever fool with a marathon race…”

This line started what I tweeted last February 19th, right after having finished the Sevilla Marathon, my 11th race in the distance. I was with my brother Javier, exhausted, in pain and very, very happy.

The (bad) preparation

Funny (and with all the intention) that I wrote “prepare well” in the tweet. The year 2016 had gone without having run any marathon race, thus breaking the series initiated in 2011. Only the half-marathon of Los Palacios with work colleague Jesús, kept me connected to some running objective. Throughout last year I had not managed to balance work with a decent training plan.

However, my brother Javier wanted to come back to Seville after his DNF (Did Not Finish) of 2015. He had trained well through the end of 2016 and wanted to achieve his PB (Personal Best). I had the incentive I needed to get back on track. I registered for the race.


Javier, Andrea, David and myself, after picking the race bibs (credit to Luca for the picture and Javi for the tweet)


2017 started with a good mileage in the first weeks, combining series training with regular long runs during the week. I would not be as fit as Javier, but I would still enjoy the race.

The progress stopped again. A fatigue alert during fast pace series, and a peak of work at the end of January disrupted the training notably.

At some point at the beginning of February I knew I would suffer. With my experience of 10 races and the 100km of Millau, I was to some extent positive about finishing, but I even doubted that I would manage to run “sub 4” as I had initially intended.

Dibujo Sevilla

I announced the race with the same traditional drawing I prepared for 2015

The race

As I already indicated in the post about the Madrid Marathon, to run in a known course is a plus. Having run in 2015, and after almost two years living Seville, the course was a familiar one, and I could mentally prepare for the ups and downs during the race, anticipating long neverending streets or crowded ones where the spirit could be cheered up.

I started modestly with 5’45” per km, with the idea Javier had suggested: “run easy first half and try to aim for a negative split, it worked for me in Dublin”. A negative split means running the second half marathon at a faster pace than the first half. Javier had managed very good his pace at Dublin and enjoyed feeling strong at the end of the race. In a race that puts your resistance to test, this strategy calls for the mental control of running slower than you are willing to in the first half.

With this in mind, I thought that with a pace short of the 6’/km, way slower that my old standard race paces ranging from 5′ to 5’30”/km I would achived this. Wrong.

Until km 15 I maintained the initial pace but I already started to feel that I would need to slow down at least for the next 10km. And I didn´t see how it could get better afterwards. At the end of the long Avenida Kansas City, near half marathon milestone I was flirting already with the 6’/km.

Benefiting from the experience of 2015, I managed the next 7km through the long streets of the east side of Seville but I already realized that this would be a tough one. Reaching km 30 I had already run at 6’30”/km some strips. I then entered a new race and I was faced with long forgotten sensations.


This mark is well known for me. It is around the kilometer that many amateur marathoners know with name the Wall (this typically may start from km26 on, depending on the runner experience), when the physical fatigue really comes in. It had not hit me as hard as in my first one in Munich, in which kilometer 32 I first saw the line “Pain goes, Pride remains” that so much motivated in my last 10km and ushered a new era in my sporting life.

However the feelings were similar. I went very slowly through Parque de Maria Luisa, already around 7’/km. I was loosing speed and energy at such a pace that the image of myself that I had in my mind was that of the submarines in the movies that are sinking (take Crimson Tide or The Red October movies, for instance). Like the scared crews in the submarine I was going down, not knowing when this pain would end…or whether I, as the shell of the ship, would resist at all.

But, as I used to say to my brother, a marathon always offers an opportunity for epic. Right crossing the km36 milestone in the beautiful Plaza de España, mixed feelings arouse and I saw a guy overpassing me with his right leg completely rigid. I noticed by the smell he had received treatment for muscular injury. Despite this, he kept running, fighting for every meter. He left me behind, but triggered a sense of resistance that I had already had in the Athens inferno.

The next 4 kms through the city center helped with the crowds cheering the runners. We passed along the Cathedral, Town Hall, and the Alameda de Hércules Square. There, a work colleague saw me and cheered me. Although we had had some discussions at work, I really appreciated his words, they did me well. I thanked him explicitly for this some days after in the factory cantine.


The final rush. After the Alameda, a short strip uphill to the Puente de la Barqueta bridge led me almost to exhaustion. At the mark of km 40 I started feeling quite bad and I took my last sip of energy gel.

In every marathon, with no exception, I marvel at the milestone 40km. It is an insane number. Even if I am done already, depending on the race, just reaching that point gives me the push of achievement I need to finish.

The last streets and I reached the Olympic Stadion. With the slowest pace in the entire race, between 7’20” and even 8’/km, I enter the race track where, like especially in Athens, Javier was already waiting, spotted me and cheered me. With 8 marathons and the 100km of Millau run together, his voice cheering me is the best energy injection. I completed the round to the finish line at a 4’30”/km sprint!!

I met him in the finish strip. He was happy as well. Altough he had suffered more than expected in the second half, he still managed to achieve his 2nd best time!


Happy finishers inside the Olympic Stadion (credit to Javier, pic was taken with his Smartphone)


My colleague Jesús, that had kept me running at least the minimum in 2016 did a PB as well with 9min over the 3 hours! I encouraged him to join once for an ultra-race.

Next objective

Almost like a beginner, in my 11th marathon I had remembered the lesson of the distance: Don´t play with it. You need to train well. With mere 600km run along 2016, I had run less than half of the previous years. I need to learn from that, and balance my time to train more constantly.

Will it help to set new objectives as a marathon for the second half of the year? Another ultra-race, as some friends are proposing?

In any case, I promise not to fool again with the 26.2 miles.

Posted in Running, Uncategorized | 1 Comment

A review of my charities in 2016

“For people with a remakable financial or managerial talent, and able to anticipate the future for the good of others, there is the moral obligation to do that”                Rober Shiller, Nobel Memorial Prize in Economics 2013

One of the most rewarding things about writing a blog is the moment when you can report about the wonderful things that people around you do to help others. I speak about charitable work. In line with the quote at the beginning of this post, although at a modest scale, the reader of this blog has seen already some initiatives that I have supported in the last two years (see category social for the dedicated posts).

Although this post comes with a couple of months of delay, the fact is that last year has been fruitful regarding charities. I want to report on the three initiatives that I support from now on and how I got to know them last year.  Is the spanish chapter of debra international, the organization supporting families with members suffering of the Epidermolysis Bullosa, the rare genetic disease characterised by extremely fragile skin and recurrent blister formation. The kind of suffering for children, and its impact on their lives, is unthinkable. In a Toastmasters (1) contest in Marbella, I got to know fellow speaker Minerva, who works as PR (Public Relations) manager for the association. After a wonderful conversation with her, I did some research and as a result I became a donor. On PR, she definitely succeded 🙂 .  This spanish association works in four axis: global citizenship, women´s rights, local sustainable development and humanitarian aid.  I learn about alianza through my primary school mate Isabel, who in a recent dinner of the class of ’93, explained about her work on it. I listened fascinated and decided to donate soon.

The best thing about learning from alianza is that I got the “expert advice” from Isabel regarding a second initiative: As she put it: “they are the first responders”. Working in similar action axis as alianza, actionaid has built on experience to provide a specific approach for support in cases of emergency and conflict. This specialization is what Isabel valued with her comment and what I bring to your attention.

As I did in the other posts related to charities, I recommend the research exercise with these organizations for many reasons, and not the least for the learning part that comes with it. Once it becomes an habit, you can learn how people help others and identify what suits you better. See for example by brother´s yearly report on charities here.

And to end the post, just a little note. I didn´t reveal this before, but every time that I report on the new projects that I´ve been acquainted with, I really get goosebumps. This time was no exception. I am looking forward to the end of this year to know and learn about new people and their projects.


(1) Toastmasters is the non-profit public speaking organization through which I have grown as speaker in the last 6 years. I had tons of fun in the process as well…



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Running in southeast asia

“The running shoes, always in the suitcase”

My brother Javier loves this quote very much and he sticks to it whatever the trip he embarks himself on. I learned the habit from him and, although not as constant as he is in following it, it has provided me with good moments knowing the cities I have visited from another perspective while, practising sport.

So, when this year I fulfilled my old teenager dream of travelling southeast asia for some weeks (“in the pursuit of the brother pea” as my father would mock me 🙂 ), my running gear was with me.

Running in the places I have visitied has been an enriching experience and in this post I want to share it commenting about that runs. I will tell chronologically as I travelled the region.

Bangkok, Thailand

The intense megacity was my first stop in a tour that would take me to five countries. I stayed in the Suk11 hostel in the crowded Sukhumvit street. With high rise hotels, somewhat creepy backstreets I needed a proper place to run. From the elevated monorail to Silom Road I spotted the meadows of Lumphini park. On the third day I went there to run.

Even though after two days I got used to the mix of high humidity, above 80%, and temperature, running in these conditions was another business. I went running two times to Lumphini Park and the first day I almost collapsed. Bangkok had beaten me at my first attempt. Around the park I completed 5,1 km at 6:35 min/km.  I was determined however to come back and try to do some sprints. Knowing the place already, and where to buy drink water, I succeeded. I a round split of 2,44 km I ran at 5:24 min/km. I had my revenge.

The Lumphini Park is surrounded by embassies and high end hotels, providing an asian version of New York´s Central Park near Columbus Circle. The running atmosphere was ok, with mix of western and asian runners in the park the two days. I recommend visitors of Bangkok to put this park on their agenda.

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Bali, Indonesia

Second stage in the tour took me to the beautiful indonesian island of Bali. There I would meet good old friend Juan, who had arranged an amazing 4 days weekend. With a program full of activities it was not until the very last morning, before taking my taxi to the airport, that I went running to the beach of Seminyak, where our villa was located. Running on beach sand is quite healthy, but it prevents you from clocking good paces…unless a storm breaks and obligues you to take shelter and run as fast as possible to get back home, which is what happened to me. Of the 5,2km that I run, the first 4 were averaging 6:30 to 7 min/km, while the last one, rushing back to the villa under the rain was at 5:10min/km with peaks of 4min/km.

Beach course in Seminyak

Beach course in Seminyak

The town and beach of Seminyak being a spot for high end resorts and villas, it was not unexpected to find westerners running or walking along with me, even though the weather and hour, 7 AM, were not the most inviting:

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After discovering the jungle and modest villages of Bali, the contrast couldn´t be bigger arriving at the high tech city of Singapore, one of the most developed enclaves in the world. At the beginning I feared that the central location of my hotel, in such an urban environment, would make it difficult to find a place to run. The entire city proved me wrong. Even though I had the Fort Canning park few minutes from the hotel lobby, in the first walk to the riverside I discovered that Singapore was a city on the run. Nice walks, bike lanes and passages made it easy for the runner to go wherever he liked. And there were dozens of them, at every hour, in the morning or the evening. Never had I seen such a density of runners, except in the race events. My pick was to run around the Marina Bay, with its fantastic skyline scenery. I was not alone in my choice. I went running at 8:30PM but the humidity, a constant in the region, was very high. The Garmin recorded two separated legs totalling around 5,1km at paces between 5:30 to 5:50min/km.

The highlight, apart from the scenery, was that on that weekend the Formula 1 Gran Prix would take place and the street race course was already set up. The organization opened it for visitors the very evening I was running, so that I had the chance to run some 100m of a strip where Fernando Alonso, Hamilton and the rest would be driving a day after. Unfortunately the Garmin did not engage the GPS signal, so I have only the time, 25s, but not the exact distance or pace.

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Kuala Lumpur, Malaysia

Next stage in the tour was the neighbouring Malaysia. In Kuala Lumpur I had a bargain price for a 4 star hotel…not precisely with the best location. While it allowed me to know parts of the city no so touristic, I really did not find a park or a good spot in that jungle of asphalt and concrete to go running. The only option left to me was real street running. Considering also the heat, humidity and packed visit program, I went running on last day at 7AM, as I did in Bali. The surroundings of the hotel were really not the best and I recorded just 2,6km. The pace at least was quite decent at 5:16min/km.

Short street course in Kuala Lumpur

Short street course in Kuala Lumpur

In contrast to Singapore, so full of runners, or even the beaches in Bali (at 7AM!) or Bangkok´s Lumphini park, the morning view of Kaula Lumpur was not very inviting. But even in these conditions, I think I spotted a fellow runner. For the pace I am not sure that he was running at all, but his sporty gear and shoes were evident…

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Siem Reap /Angkor, Cambodia

Final stage of the southeast asian tour was the imperial region of Angkor, where the visit to the legendary khemer temples was planned. Although I will ellaborate more on that visit in a dedicated post, here I focus on the running side. The small city of Siem Reap is the base from which to visit the woods where the temples are located. Again, the location of my lodging was not very centric and offered the same “real life” taste I had had in Kuala Lumpur. The adjacent streets, in contrast to Malaysia, although not especially inviting, had less traffic and were more comfortable to run. I reserved the day before the departure for a morning run. At 11AM I started and parted for the royal gardens in the city center. In total 5km at a relaxed pace of 5:38min/km, ok considering the heat and humidity conditions that I had, by that time, gotten used to.

Circuit in the city center

Circuit in the city center

The streets offered a view of small shops and tents in the sidewalks, with nobler buildings and museums as I approached the city center and the royal gardens. This time, however I didn´t find any fellow runner. No one. I noticed some curious faces looking at the guy running along the street, but I continued. In fact, with Singapore, this run was the most comfortable of the trip. I had had a great stay in the city and had enjoyed inmensely the visit to the temples. I guess my face reflected it 🙂

Preah Ang Chorm temple in Siem Reap´s Royal Gardens

Preah Ang Chorm temple in Siem Reap´s Royal Gardens


In summary, having my running gear in the suitcase allowed me to run some 26km spread in 6 days during the 3 weeks. This modest amount of kilometres is clearly not enough to keep up with a typical training plan, but provides for an enriched travel experience, for example observing the differences in the “runner” atmosphere among the countries. I could gain also new running experience having suffered that extreme humidity in combination with heat. Now I know how my body reacts to it, as learned also troughout the years running in the snow, under heavy rain or with chilling low temperatures. And finally I reinforced the connection feeling with the cities and places I visited, and it was definitely healthier than not doing it.

For my next long holidays be sure I will repeat it.

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Quieting the boom – book review

With the undertitle “The Shaped Sonic Boom Demonstrator and the Quest for Quiet Supersonic Flight”, this ebook is a new release of the NASA ebook series, and comes just after the previous one devoted to the U-2 which was also reviewed here. From author Lawrence R. Benson, it provides historical overview on the more than 40 years of research towards quiet and efficient supersonic flight.

Cover of the book (credit to NASA)

Cover of the book (credit to NASA)

In these days when NASA has revived the effort to make the commercial supersonic flight possible, contracting to Lockheed a new X-plane, this book summarizes the research started in the 50s, after the first supersonic aircraft made “audible” the problem of the sonic boom, reviewing the main research programs that followed: the SST (Supersonic Transport), SCR (Supersonic Cruise Research), HSR (High Speed Research) and the two phases of the QSP (Quiet Supersonic Platform) which resulted in the Supersonic Business Jets demonstrator, which form the basis for today´s effort.

With over 290 pages along 9 chapters and four useful appendixes, the book can be considered as a reference and starting point to deepen in each of the specific programs that were devoted to the sonic boom minimization effort.

The historical review is quite extense, therefore the following notes briefly provide my understanding of the progress made in that quest and the highlights of the different programs. I have to remark again, as I did in other reviews of the NASA ebook series, that some knowledge of aerodynamics is needed to follow the technical descriptions.

Protagonists and theoretical foundations

Starting point are the first encounters with the sonic boom during the flight test campaing of the Bell X-1S with Charles “Chuck” Yaeger at the controls. The sonic boom, or the accumulation of pressure waves, or energy, provoked by a body moving faster than Mach 1 was soon characterized by the N-wave form and the sonic cone:

N-wave and sonic cone

N-wave and sonic cone (NASA)

The first significant paper on the N-waves and perceived pressure levels (measured in pounds per square feet or psf) date from 1955 paper “The Relation Between Minimizing Drag and Noise at Supersonic Speeds” of Gerald Whitham and Frank Walkden, that established relation between the sonic boom and aircraft lift and volume. These two factors would be on the focus of all the minimization effort during the next decades.

Other important names cited throughout the book are those of A. Richard Seebass and Albert R. George of Cornell University as well as Wallace Hayes of Princeton, who advanced the provious theoretical research towards optimization of aircraft designs. The prolific work of these and other men during the 60s can be reviewed in the papers compiled of the sonic boom research conference of 1967. See the conference´s report in this link [5MB pdf, 117 pgs]. The report lists the main lines of research at the time: propagation of the pressure waves, effects of atmosphere on propagation, effects of aircraft shapes on N-waves generation and first results on perception and effects of sonic booms on people and buildings on the ground.

This topic, the complaints of public to sonic booms would suppose the paramount barrier to the evolution of supersonic aircraft for continental flight, and due to regulation issued at that time, it lasts until today. During those years the consensus was established that an acceptance level of perceived boom would be around 1 psf. That would be the target for the optimization programs to come.

N-wave propagation (NASA paper)

N-wave propagation (NASA paper)

The theoretical efforts of the 60s crowned with the 1974 paper “Design and Operation of Aircraft to Minimize their Sonic Boom” by Seebass and George. With the advent of the computerized fluid dynamics, or CFD, it ushered a new era of computed models for boom minimization and propagation analysis.  NASA´s Christine Darden and Robert Mack are two of the key names for those years, where blunt nose shapes with higher drag were identified as generating quieter sonic booms.

Darden-Mack´s "low drag paradox" for boom minimization (NASA)

Darden-Mack´s “low drag paradox” for boom minimization (NASA)

From then on, a myriad of research projects went on to model the aircraft desings, predict their N-waves and simulate the propagation. The book goes on summarizing many of them that took place during the 80s and 90s.

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In parallel to the review of theoretical work, the book gives account of the main programs which involved flight testing (also including boom perception on ground test in some cases). The early programs of the 60s, 70s and 80s took benefit of existing platforms for real flight research, even though they involved extensive wind tunnel testing of dedicated optimized models (especially in the 80s, in order to validate CFD results).

Later on, the QSP and its follow up SSBJ programs led to the creation of a dedicated sonic boom research prototype. The following are my notes on that.

Early research programs: SST, SCR and HSR

As noted in the first chapters of the book, the sonic boom research benefited indirectly from the flight test of many US Air Force fighters and X-planes, especially during the 60s, such as the XB-70 Valkyrie or the Lockheed SR-71.

The main program at the time was the Super Sonic Transport (SST) which, from early 60s to the 70s, grouped the efforts of academia, NASA, FAA, US Air Force and industry to achieve a supersonic airliner for continental flights. Alone NASA funded $1bn in research in that decade related to the program. Altough the public opposition to the perceived levels of sonic booms grew as to put an end to the program in 1971, the design concepts and target levels established then helped to define boundaries to the problem for subsequent studies.

Boeing proposal for SST program, the 2707-300 (NASA)

Boeing proposal for SST program, the 2707-300 (NASA)

The next cited program following up the SST is the Supersonic Cruise Research (SCR), that is described as amalgamating a series of subprograms related to supersonic flight: Advanced Supersonic Technology (AST) and Supersonic Cruise Aircraft Research (SCAR). The book revises the objectives of the proposals of these programs, in the range of a 300ft long A/C, for 2 Mach cruise at around 60.000ft for a maximum of 1psf perceived on ground.  The program, which ended 1981, went along benefiting from the early results of CFD-backed designs and simulation of propagation of N-waves.

Chapter 4 of the book deals with the next program, the High Speed Research (HSR). It is noted that although different programs went on separately during the 80s (USAF NSBIT or NASA´s High Speed Cruise Transport) it was not until 1990 that the government launched a new ambitious effort under NASA leadership. That was the HSR, which comprised two phases. The first one, lasting until 1995, supported studies on aircraft configuration and design, acoustic propagation as well as continuing the noise acceptability research. This Phase I was backed with flight test with a SR-71 and a chase F-18 that took measurements of the acoustic near field of Blackbird. The second phase narrowed the design configuration to an airliner of 320ft long for 300 pax, flying at 2,4 Mach only over ocean and subsonic overland. The flight testing continued with the SR-71, for which optimized designs were proposed, followed now by an F-16XL for near and mid acoustic field measurements.

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However, the book details that, by late 1998, the HSR program confronted a combination of economic, technological, political, and budgetary problems, which led to its termination in 1999.

Modern programs: QSP and the F-5 SSBD

Last chapters of the book focused on the last 15 years of work, where focus has been put on advancing a smaller, but viable, supersonic aircraft for overland flight. The program that is discussed in the book is the Quiet Supersonic Platform (QSP). This program finally made the case for the arguments of Richard Seebass, that an aircraft in the size of a business jet and with an optimized shape for boom minimization could attain admissible noise levels overland.

Launched in 2000, the program established ambitious objectives and revamped existing lines of investigation across manufacturers, universities and insitutions. The book provides a summary of the projects and the roadmap of its two main phases:

Quiet Sonic Platform roadmap (NASA)

Quiet Sonic Platform roadmap (NASA)

I loved to read that among the many studies revised within the QSP, one had been done by spanish CASA, now part of my company Airbus DS, that at the time was building Northrop F5s under license for the spanish Air Force. A happy coincidence as I discovered later.

In fact, right after the QSP launch, Northrop-Grumman Corporation (NGC), decided to jump into the program and offered to modify an F5 with an optimized form. The decades of development of CFD optimization for boom minimization crystallized in the ultimate sonic boom protoype, the F-5E SSBD, for Shaped Sonic Boom Demonstration.

The result of decades of work was a very good match between computed simulations of acoustic propagation of the boom and actual flight test measurements. The figure below compares CFD computation vs. pressure wave of an unmodified F-5E measured from a chase plane F-15:

F-5E pressure data. Simulation vs. flight test measurements (NGC)

F-5E pressure data. Simulation vs. flight test measurements (NGC)

In parallel, the book goes on giving detailed account of the shape optimization effort, model fabrication and wind tunnel testing up to manufacturing of the full scale prototype:

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History was made on August 27th 2002, when the F-5 SSBD performed the first demonstration flight test. The measurement arrays on ground confirmed the mitigation of the sonic boom, the characteristic N-wave had been flattened thanks to the new fuselage shape:

Historic flattened N-wave of the F-5 SSBD vs. baseline (NASA)

Historic flattened N-wave of the F-5 SSBD vs. baseline (NASA)

The reduction of the pressure peak was attained, from 1,2 psf to 0,8 psf, below the admissible 1psf target. The program had been a success.

The book describes the further tests of the F-5 SSBD with different measuring arrays on ground, utilization of gliders and other chase aircraft for near and mid acoustic field measurement.

In the last chapter it is noted that after the SSBJ success, the program lost momentum, coinciding in time with the 11-Sept attacks and the financial crisis. It lists a series of smaller follow up research projects including the design of maneuvers for focusing or minimizing the sonic boom (performed with a F-18), the nose spike installed on a F-15 and the characterization of its pressure signature.

Current efforts and final comments

The last paragraphs of the book note that, altough at a slower pace, the advancement of viable civil supersonic flight has not stopped. It describes the last round of US government funding from 2009 on and the proposals of manufacturers for supersonic business jet in the range of 30 to 100 passengers. It cites some of the projects of NASA, Lockheed or Aerion, a project of supersonic business jet born in the wake of the programs discussed in the book.

In summary, this book is my opinion the perfect reference document to understand 40 years of supersonic research and testing. It is represents the entry point to put in perspective the different research fields, the successes and the failures and identify where future lines of work could be opened.

However, as the book was written 2013, it did not capture the advent of new private initiatives such as Boom, that, in the fashion of the Aerion project, pursues a supersonic business jet. But, more than that, it misses the opening of the new era of X-planes.

I will surely post on that, as NASA´s New Horizons 10 year initiative lays foundation for a new series of experimental aircraft, including the revamp of the quiet supersonic flight. For that project, Lockheed has been awarded a $20mio contract for the design of the next demonstrator.

On the personal side, apart from reading in the book about CASA´s past contribution to the sonic boom reduction effort, I am delighted to see how my colleagues in Airbus are engineering partners to the Aerion AS2 supersonic business jet program.

In any case, whatever the outcome of these efforts, the future of the civil supersonic flight will be based on the decades of work and the flight tes results of the successful F-5E SSBD, the pelican:

F-5 SSBD, "the pelican" in flight (NASA)

F-5 SSBD, “the pelican” in flight (NASA)

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Free falling

Not describing a chaotic life period, falling apart like Tom Cruise sung on Jerry McGuire, but meaning skydiving, free falling is literally what a group of work colleagues did last July.

Whitin the group of engineers supporting flight development and operations at Airbus in Seville, we are fortunate to have the frenchmen Dany and Jean Manuel, with hundreds, if not thousands, of jumps from an airplane on their logs. Some weeks ago, they proposed the activity to a group, and 8 of us enthusiastically signed up for the morning of Saturday 16th.

Jumping from an airplane has as much of experiencing an adrenaline boost as it has of overcoming the atavic fear of falling. For more than one of our colleagues, this fear would grow until the very moment of jumping. I have to say that, except for some minutes on thursday night, it was not my case. Believe me. What follows are my personal notes about this experience.

Jean Manuel and Dany jump with andalusian Skydive Spain club, located in airfield La Juliana, just 20min a ride from Seville. Apart from them, who have the license to jump on their own, the rest of us signed up for the so called “tandem jump“, that is, to jump tied together to an experienced instructor who launches and controls the parachute.

Tandem jump with instructor (up with chute) and jumper below (from Skydivespain web)

Tandem jump with instructor (up with chute) and jumper below (from Skydivespain web)

The jump is made at 15.000ft, or 4600m, from a Dornier Do 28d which, with a capacity up to 8 pax and a big lateral door, is especially suited for this activity.

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The “dive” consists of about one minute of “free fall”, reaching a speed up to 130mph, followed by the deployment of the chute, in a controlled descent of around 5 to 8 minutes where the instructor allows the jumper to take control for a while.

Before embarking into the Dornier for the ascent flight to jump altitude, a briefing takes place on ground, where the basics are explained:

· Basic positions: a) in the airplane prior to the jump and during the free fall segment, with the body in a concave position with arms and legs bent upwards in order to lower the center of gravity for better control b) during the controlled descent, in vertical position and c) at landing, with jumper´s legs held high to avoid tackling of the instructor ones.

· “Shoulder taping” communication code: by means of taping on our shoulder, with one or two taps, instructors would let us know when to go to different basic positions and when to move our hands free or holding them secure by grabing the breast straps of our jump suit.

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Following these basic instructions, one can leave the rest to the instructor and be confident that they are doing this several times every day, nothing should happen… 🙂  And indeed nothing happened to us! That thought at least allowed me to enjoy every minute of the ascent flight in the Dornier to 15.000ft laughing at the jokes of the instructors. It allowed me to not panic seeing others jump while I had the last turn, and definitely enjoy shouting from excitement in the first seconds of the jump.

One key aspect to get the maximum out of the jump is the confidence created by the instructor. In my view, these guys from Skydive are good at “reading people” and knowing who needs to relax with a joke or who needs serious instructions to follow. My instructor set the tone with his advice: “never go to the airplane without me, I carry the chute, not you, so you can jump alone, but then you will do it only once…” 😄 Great guy!

Me with instructor Manolo behind, tying tight the suit straps. Great mood!

Me with instructor Manolo behind, tying tight the suit straps. Great mood!

The free fall minute is a great experience loosely similar to floating in the water, where the aerodynamic noise doesn´t let you hear the instructor (thus the shoulder-taping). The controlled descent is more relaxing, and the instructor may allow the jumper to control the chute, showing highlights of the landscape visible from the sky, thus engaging in a great experience.

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After the briefing and during the preparation for the flight, we were made familiar by the instructors with some aspects of this sport. They explained us the climatic constraints, where autum and winter are preferred to summer due to termic currents, dangerous for this activity, and which makes Spain and Seville a real hub in winter for european skydivers. They talked about to the materials and rituals, from the different sizes of chute canopies necessary to control the descent speed (from 350sq ft for tandem jumps, to 120sq ft for experienced jumpers to the crazy 60sq ft ultrafast canopies for the risk seekers), to the art of repacking (where it seems that Dany especially excels) the canopy and all the harnesses.

As the group had to split among separated flights for the jumps, some of us were always present at the landing area to cheer and welcome the jumpers, who were high on adrenaline. We shared our feelings and some beers at the end in the airfield cantine.

Our "Skydive social club" in high sipirt after the jumps

Our “Skydive social club” in high sipirt after the jumps

Although Dany told us that what we did was in fact “just falling” (rather than the more complete experience of diving, as the jumpers do when going solo) this was a great event, a demonstration for some that almost every fear can be overcome and a perfect ocassion to share more of avgeek spirit with great colleagues. As we all said, this was the first time, but definitely won´t be the last.

“… Freeee, free faaaalling!!”

To finish the post, I leave you a video from Skydivespain´s website with an example of a tandem jump:

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