Friday, July 31, 2015

Book Review: Debrief: A Complete History of U.S. Aerial Engagements 1981 to the Present

Craig Brown
Debrief: A Complete History of U.S. Aerial Engagements 1981 to the Present
Atglen, PA: Schiffer Publishing, 2007
Category: Aviation History

Rating: 5-Stars

For anyone who loves first-hand accounts of air combat, this book is a must-have.  Covering the period from 1981 to 2006, it provides a summary of every air-to-air kill recorded by U.S. pilots during that period.

The author provides a brief introduction for each description, introducing the pilots involved and the mission they were assigned to at the time.  Then he "gets out of the way" and allows the pilots to retell their experiences in their own words.

Libya during the 1980s, through Desert Storm in 1991, to Operation Allied Force over Bosnia in the 1990s - it's all here, accompanied by a wide assortment of photographs and illustrations.  Strap-in, and enjoy the ride!

Thursday, July 30, 2015

Book Review: Loud and Clear

Iftach Spector
Loud and Clear: The Memoir of an Israeli Fighter Pilot
Minneapolis, MN: Zenith Press, 2009
Category: Israel Air Force - Biography

Rating: 4-Stars

A book is about more than just a simple retelling of a story.  It is about the relationship between the reader, the writer, and the story.  When it comes to Iftach Spector, that relationship is complicated.

On the one hand, Spector was a first-hand eyewitness to many major events in the history of Israel's Air Force.  His first squadron assignment in December 1960 was to the Scorpions - under Yak Nevo, the pilot who had literally written the book on Israeli air combat tactics.  In the course of his career, Spector's path would repeatedly intersect those of such figures as Zorik Lev, Ran Ronen, and Shmuel Hetz.  Spector would take part in every major Israeli war and operation from the 1967 Six Day War, to the 1982 Lebanon War - with more than his fair share of MiG kills along the way.  The insights that he provides into each individual, and into each event are invaluable.

On the other hand, as becomes apparent through the pages of the book, Spector's own relationship to his peers and subordinates was somewhat terse, and removed.  A loner since his youth, Spector repeatedly made choices that cast into doubt his personal judgement.  As newly appointed commanding officer of the 101st fighter squadron, Spector's demanding, sometimes dictatorial leadership style succeeded in alienating most of the pilots under his command.  In another episode, years later as base commander of Ramat David he would insist on taking part in the historic raid on Iraq's Osirak nuclear reactor - bumping a younger pilot with far more hands-on experience in the F-16.  Past his prime and less familiar with the airplane, Spector would become disoriented over the reactor site, dropping the only two bombs that missed a direct hit on the reactor dome.  Still later, long after retirement, Spector would write a letter in protest of Israeli tactics that called on the IAF to carry out targeted killings of individual terrorist leaders in Gaza - a letter that was published precisely as waves of suicide bombers were targeting Israeli bus stops, restaurants, and night clubs on a daily basis.  His public letter of protest could not possibly have been more poorly timed.

So for a supporter of Israel and a student of modern Israeli military history, the relationship with this book will be complicated.  Spector was an expert dogfighter, and delivers detailed accounts of historic engagements.  He was also, however, a man - flawed like any other - who lays bare many of those flaws for all to see.  Still a great book, still a lot of history to absorb, but . . . complicated.

Wednesday, July 29, 2015

Book Review: Synthesis of Subsonic Airplane Design

Egbert Torenbeek
Synthesis of Subsonic Airplane Design
Delft, Netherlands: Delft University Press, 1988
Category: Aerospace Engineering

Rating: 2-Stars

Many years ago, when I was a teaching assistant for Airplane Design at the University of Michigan, we had two professors who would alternate as teachers for the course.  The one professor used a combination of Daniel Raymer's Aircraft Design and the first two volumes of Jan Roskam's Airplane Design series as the textbooks for the class.  The other professor used Torenbeek's Synthesis of Subsonic Airplane Design.  The students who learned under the former professor walked away with a far superior understanding of the mechanics of airplane design than did those that learned under the latter.  That was partly due to the professor, but it was also a reflection on the two sets of textbooks.

Torenbeek's book goes through the motions of airplane design calculations.  It has the essential mathematics laid out.  But it has neither the breadth and depth of Jan Roskam's multi-volume set, nor the ease of access of Dan Raymer's writing.  While I still keep a copy of Torenbeek's work on my own book shelf as an alternative reference (in case I want to explore trends using an alternate weights model, for example), this is not the book that anyone would want to learn airplane design from.

Tuesday, July 28, 2015

Book Review: Fire in the Sky: Flying in Defence of Israel

Amos Amir
Fire in the Sky: Flying in Defence of Israel
Barnsley, UK: Pen & Sword Aviation, 2005
Category: Israel Air Force - Biography

Rating: 4-Stars

Brig. Gen. Amos Amir served in the Israeli Air Force during that crucial period spanning from the 1956 Sinai Campaign, to the 1982 Lebanon War.  Both a Mirage and Phantom pilot, Amir's writing includes the kind of details that help to bring his experience to life, describing not only the events that happened, but the scenery and sensations that he experienced at the time.  Take for example his description of a reconnaissance mission over Egypt:
"The shimmering expanses of the Bardawil lagoon now came into view in all their beauty, and I had a couple of seconds free to make a mental note of the spot's extraordinary magnificence.  It even seemed to me that I caught a glimpse of a huge flock of flamingoes covering part of the blue-green lake."
The chapters of the book alternate between wartime events, and flash-backs to Amir's experiences as a child, then as a young man, and later as a cadet learning to fly.  For me, however, part of the charm of the book comes not merely from Amir's own retelling, but from the individuals and events that his life intersected - offering an alternate vantage point for recalling events and people that were also prominently featured among other memoirs and other pilot interviews.  There are Amir's own rememberances of the bright smile and gentle demeanor of Zorik Lev, for example - the Israeli pilot perhaps most fondly remembered among all his peers, and who died in the 1973 Yom Kippur War.  Or there were the missions that Amir flew as wingman to Ran Ronen, who was perhaps Israel's most famous squadron commander of the 1967 Six Day War.  Then there are his first encounters flying the Mirage, the fighter that formed the backbone of Israeli air power during the Six Day War: an elegant French weapon, contrasted sharply against the powerful but brutish F-4 Phantom.

Although shorter than some memoirs, Amir's book stands as an able companion to the story of the Israeli Air Force: its formation, evolution, and the men who made it all possible.

Monday, July 27, 2015

Aircraft Performance - Part 2 - Video and PDF

Video edition for Part 2 of the Aircraft Performance Review.

Original chart pack is available below.

Aircraft Peformance - Part 2 - Basic Calculations

In Part 2 of this series on aircraft performance, we will be discussing some of the basic calculations that go into aircraft performance evaluations, with an eye towards gaining a basic appreciation for the mathematics involved.

The cornerstone of any performance or mission analysis calculation, will be the airplane's drag polar.  For the purposes of this presentation, we will be looking at a classical drag polar representation.  There are modified versions of the drag polar in use, but for our purposes, the classical representation should serve just fine.
The drag polar relates the airplane's total drag to a combination of the zero-lift, or parasitic drag, and the induced drag - or the drag due to lift.  The induced drag, in turn, can be related to the lift coefficient squared, divided by the airplane's aspect ratio and the aerodynamic efficiency, or Oswald's efficiency.  It should be noted as well that the aspect ratio is itself related to the airplane's wing span squared, divided by the wing reference area.

In order to be effective, the drag polar needs to take into account a variety of real world effects.  The first element to note is that the wing reference area is itself a somewhat arbitrary quantity.  It's what we would get if we were to extend the wing leading edge, and the wing trailing edge all the way to the airplane's centerline.  What this means in practice is that the aerodynamic efficiency must be adjusted to take into account such real world effects as the wing cross section, wing-to-fuselage integration, whether the design has a canard or a horizontal tail, and so forth.

Similarly, the parasitic drag will be a function of the airplane's wetted area, the coefficient of friction (book keeping the effects of rivets and similar protrusions), and the Mach number.  Particularly in transonic and supersonic flight, the parasitic drag can be expected to rise significantly due to wave drag.

Finally, in addition to being affected by fuselage integration, wing cross section, and similar effects, the aerodynamic efficiency will also be a function of the airplane's Mach number, and aerodynamic loading (or g-loading).

The mission analysis in turn is calculated by breaking the mission down into small segments, which can then be analyzed for fuel burn.  Effectively, the airplane is analytically "flown" through the mission.  In its most simple form this principal can be expressed by the Breguet range equation - which also provides insight into what these equations can tell us.
The Breguet range equation relates the range of an airplane to its initial weight, at the beginning of the flight, and its final weight, at the end of the flight - in a logarithmic manner.  In other words, the relationship will be highly nonlinear.  Range is also affected in direct proportion to the cruise velocity, as well as the lift-to-drag ratio, and is inversely proportional to the thrust specific fuel consumption (TSFC).  The Breguet range equation, however, is also accurate only if the velocity, fuel consumption, and lift-to-drag ratio remain constant.  It should also be pointed out that the lift-to-drag ratio is itself an output of the drag polar.
More detailed mission analyses will break a mission down into a series of segments, each small enough that variations in speed, altitude and specific fuel consumption become negligible across that particular segment.  As an example, an equation for a constant altitude and speed cruise segment is portrayed here.  For a complete mission, each segment of flight would need to be evaluated separately, with longer segments - such as cruise - further subdivided.

Part of the real beauty of the relationships described here, is that they allow us to draw comparisons and conclusions from different design trades without necessarily exercising a detailed mission calculation.  Consider for example the Boeing 777X currently under development as a more fuel efficient, longer range development of the original 777 design.  The 777X is expected to increase the wingspan of the airplane from the 212-ft 7-in found on the 777-200LR, to 235-ft 6-in for the 777-8X - a 10.8% increase.

From the drag polar, the maximum lift-to-drag can be calculated from the relationship shown below.  Note that the lift-to-drag ratio is related to the square root of the wing aspect ratio, which in turn is related to the wingspan squared.  Assuming a constant wing area, therefore, we would conclude that the 777X should offer a 10.8% increase in range over existing 777 models - just by virtue of the increased aspect ratio alone.
This of course, might lead us to wonder why Boeing did not take advantage of an extended aspect ratio design much earlier.  The answer to this lies in the structural limitation for an all-metal wing.  The existing 777 design represents the practical limit for airline aspect ratio for an all-metal structure.  What makes the higher wing span and aspect ratio of the 777X possible is the introduction of a composite structure.

Again, a great deal of insight can be gained just by virtue of examining the underlying relations for range and the drag polar.

Sunday, July 26, 2015

Lou Lenart - USMC Veteran and IAF Volunteer - 1921-2015

Capt. Lou Lenart in his USMC uniform
in 1945.  (courtesy photo)
Lou Lenart, a World War II American war veteran who volunteered to fly for Israel during the 1948-49 War of Independence, passed away this past week.  He was 94.

Born as Layos Lenovitz in a small Hungarian village in 1921, his family moved to the United States when he was 10.  His family settled in the Pennsylvania town of Wilkes-Barre, where he became the target of anti-Jewish taunts and beatings.  Toughened by his youthful experiences, Lou would go on to enlist with the U.S. Marines, because "I heard they were 'first to fight' and I wanted to kill as many Nazis as I could."  Lenart became a fighter pilot, flying the F4U Corsair in the battle for Okinawa.  Discharged at the end of the war, and facing continued anti-Semitism in the U.S., Lou volunteered to become a pilot for the newly established Israeli Air Force in early 1948.

At the time, Israel was facing an invasion by five Arab armies, while the Western allies - the United States, United Kingdom and France - were enforcing an arms embargo on the new Jewish State.  Whereas the Arab armies of Egypt and Jordan were being supplied and trained by the British army, and the armies of Syria and Lebanon were being supplied and trained by the French, Israel's army relied on clandestine arms deals to equip its new armed forces.

Thus it was that in May 1948, with Egyptian troops marching through on their way to Tel Aviv, that the only fighter planes available to the  Israeli Air Force were a handful of German-designed Me 109 fighters, equipped with engines borrowed from Stuka dive-bombers - newly arrived in crates from Czechoslovakia.  Four fighter planes was all that the Israeli Air Force had at the time.

The original plan had been to use the four airplanes to stage a surprise attack on the Egyptian airfield at El Arish.  However, on May 29 they received an urgent plea for air support from the Israeli defenders south of Tel Aviv, where the Egyptian army had captured the town of Ashdod, just 17 miles from Tel Aviv and 10 miles from the Tel Nof airfield.

As the most experienced pilot of the new Air Force, Lou Lenart was chosen to lead the first sortie of Israel's first fighter squadron.  Making multiple passes in the face of heavy anti-aircraft fire, the attack succeeded in halting the Egyptian advance.  Unaware of the truly meager number of fighters that the Israelis had at their disposal, the Egyptian officers ordered their troops to dig in while they waited for direction from their headquarters in Cairo.  Lou Lenart had led the mission that saved Tel Aviv.  As he would later testify, "It was the most important moment of my life, and I was born to be there at that precise moment in history."

Lou Lenart's passing this week comes as a sad reminder that we are fast losing the last survivors from that bitter era.  World War II, the Holocaust, and Israel's War of Independence, is fast becoming the exclusive reserve of history books, and legend, as the last individuals with first-hand memories of that era are lost to us.

Four rag-tag fighters, cobbled together from parts in different factories.  An assorted crew of volunteer pilots: Lou Lenart, the former U.S. Marine; Ezer Weizman and Modi Alon, who had been trained in the RAF but had never seen combat; and Eddie Cohen, a South African volunteer.  We often forget by what a razor thin margin Israel's independence was established.  Eddie Cohen's fighter would be shot down on that sortie, and Ezer Weizman's would be damaged on landing.  Too often we take for granted the survival of the free society in which we live - in Israel and the United States, both then and now.

Lou Lenart would go on after the war to participate in the covert evacuation of Jewish refugees from Iraq to Israel, and later became an airline pilot in Israel's national airline, El Al.

I cannot help but feel that we are today, a little poorer for his passing.  As if part of our collective memory was being lost.  Rest in peace, Lou.  May we never forget all that you, and so many others gave.


Chawkins, Steve. "Lou Lenart Dies at 94; War Hero was 'The Man who Saved Tel Aviv.'" Los Angles Times, July 22, 5015.
Dolsten, Josefin. "Lou Lenart, US Pilot 'Who Saved Tel Aviv,' Dies at 94." The Times of Israel, July 21, 2015.
Pressfield, Steven. The Lion's Gate: On the Front Lines of the Six Day War. New York: Penguin Group, 2014.

Saturday, July 25, 2015

Book Review: Air Warfare in the Missile Age

Lon O. Nordeen
Air Warfare in the Missile Age
Washington DC: Smithsonian Institution Press, 2002
Category: Aviation History

Rating: 5-Stars

Air Warfare in the Missile Age provides a comprehensive overview of how aerial warfare has evolved over the decades - from the Vietnam War beginning in 1964 through the Balkan Civil Wars during the 1990s.  There are of course, many books that have been written covering many of these subjects in great detail.  What sets Nordeen's book apart is the broader perspective that it provides for how air war has been conducted, and has changed across the decades.

Nordeen mixes first-hand accounts from many of the crucial conflicts, with summaries of the role of air power in each confrontation, and the armament and training of the respective air forces.  His rolling, easy-to-read style helps to make the information readily absorbed.  The book further supplements the text with a variety of tables that help to quickly summarize the respective losses and victories of each combatant, as well as the aircraft and weapons involved.

Although the book includes conflicts that have been heavily covered elsewhere - such as the Vietnam War and Arab-Israeli Wars, it also provides an overview for conflicts that are less well known, including the Indo-Pakistani Wars of 1965 and 1971, the Iran-Iraq War of 1980-1988, and the Balkan Civil Wars of the 1990s.

Now in its second printing of its second edition (released in 2010), Air Warfare in the Missile Age offers a sweeping overview of how modern air power continues to evolve and change the face of war.

Friday, July 24, 2015

Book Review: The Design of the Airplane

Darrol Stinton
The Design of the Airplane
New York: Von Nostrand Reinhold Company, 1983
Category: Aerospace Engineering

Rating: 4-Stars

Unlike many of the other airplane design texts reviewed here, Darrol Stinton's book was aimed not at the commercial or military aircraft designer, but at the home-built airplane market.  As such, the author has striven to provide additional descriptions and explanation in an attempt to keep his text accessible.

This then, is what makes Stinton's book unique, and for some, a treasure.  Well written, with plenty of figures, Stinton succeeded in producing a useful text for a market that is less well served by other, more detailed volumes.  You won't find any methods for dealing with transonic drag rise or the effects of compressibility on control surface effectiveness, for example, but you will find plenty of practical advise and descriptions for the subsonic aircraft designer.

Stinton's book was actually my own first aircraft engineering text - long before I had entered graduate school, or the university.  Even today as an aviation professional, I continue to appreciate Stinton's text as a good go-to guide under circumstances where other volumes might be less clear or practical.  An excellent starting point for many analyses, or even just to gain an understanding of the mechanics of airplane flight in general.

Thursday, July 23, 2015

Book Review: Solitary

Giora Romm
New York: Black Irish Entertainment, 2014
Category: Israel Air Force - Biography

Rating: 4-Stars

Giora Romm was the first Israeli fighter pilot to make ace - shooting down five opposing aircraft while flying the Mirage III during the 1967 Six Day War.  Only a few years later, on Sept 11, 1969, he would be shot down by an Egyptian surface-to-air missile during the War of Attrition.  Romm would spend the next three months as a prisoner of war in Egypt, bed-bound by the injuries sustained during his ejection.

Solitary is the story of Giora Romm's captivity, recovery, and eventual return to flight.  The descriptions of his interrogation - from the beatings to solitary confinement - is punctuated by flashbacks to his life in Israel: attending boarding school; earning his wings; dinner at a restaurant in Gedera after a night-time flight.  His left arm shattered, both legs broken, Giorra Romm would eventually heal - left with an arm that would never completely straighten and with a right leg two-inches shorter than his left.

Despite all that he had been through, and the painful rehabilitation that followed, Giora Romm would insist on returning to flight status - going on to fly the Mirage fighter yet again during the 1973 Yom Kippur War.

At its heart, Solitary is not a tale of air combat.  Romm's descriptions of his air battles are relatively terse, lacking the sweeping vistas and descriptions of other first-hand accounts.  What this book is, however, is a tale of determination.  The story of a man who refused to give up, even when doctors told him that he would never fly again, even when the Israel Air Force offered him a desk job, or a quiet career as a transport pilot.  Giora Romm's determination is what shines through: the qualities that made the very best of Israel's fighter pilots the successful warriors that they were.

Wednesday, July 22, 2015

Book Review: Fighter Combat: Tactics and Maneuvering

Robert L. Shaw
Fighter Combat: Tactics and Maneuvering
Annapolis, MD: Naval Institute Press, 1985
Category: Aviation History

Rating: 4-Stars

For years Shaw's book was part of the required curriculum at the U.S. Navy's "Top Gun" fighter weapons school.  What it offers is a rare insight into some of the tactics of a modern air force.  This includes basic fighter maneuvers (such as the high and low yo-yo, and scissors), but more importantly tactics for one-on-one, two-on-one, two-on-two, and multi-aircraft engagements.

The chapters dealing with two-on-two fighter engagements are probably the most valuable, and the most hard to come by from other resources.  A wingman is more than just another set of eyes, and in any truly professional air force the wingman does more than just staying glued to his lead's wing the entire engagement.  There are a variety of modern tactics that make maximum use of a wingman, including "double attack" and "loose deuce".  In essence, a professional air force must operate as a team.  That is what makes a pair of fighters far more deadly than two airplanes with one leading and one following.  Working together, two aircraft are many times more lethal than one - as this book makes clear.

There will be technocrats, of course, who will argue that in the modern missile age, the kind of tactics that Shaw describes are no longer necessary.  Nothing could be further from the truth.  A pilot is not a passenger, and the electronics - as amazing as they have become - do not do the work for you.  Energy management is essential in any air combat engagement, whether within visual range or beyond.  A pilot has to know how to bring his weapons to bear for maximum effect without giving his enemy the advantage.  Moreover, even in a missile age, during the large-scale air engagements of the 1991 Gulf War, over half of all air-to-air kills occurred within visual range.  A pilot is a tactician, not just a passenger or a radar operator.

This book is not a novel, and not a biography.  It was not intended for the casual reader.  Like a textbook, you have to be paying attention and taking notes as you read.  But for anyone who wants to understand what goes into fighter tactics - and not just what the movies portray - this book is an exceptional find.

Tuesday, July 21, 2015

Book Review: Eagle in the Sky

Ran Ronen
Eagle in the Sky
Tel Aviv: Contento De Semrik, 2013
Category: Israel Air Force - Biography

Rating: 5-Stars

Ran Ronen has been described by the men who served under him as "the greatest squadron commander ever."  A man who exemplified the ethos of the Israeli fighter pilot, Ronen was among Israel's earliest high-speed reconnaissance pilots, flying Mirage fighters deep into enemy territory to gather intelligence in the years prior to the Six Day War.  The commander of Squadron 119 in 1967 (the "Bat" squadron), he ran a rigorous training regimen - and was rewarded with the only squadron not to loose a single pilot or aircraft throughout the Six Day War.  When Shmuel Hetz, Israel's first F-4 Phantom squadron commander was later killed during the War of Attrition, Ran Ronen would be selected to rebuild the shattered squadron, leading it into battle throughout the latter days of that war.  During the 1973 Yom Kippur War, Ronen was a base commander, flying F-4 Phantoms on some of the most hazardous missions of that conflict.

Ronen was an Israeli legend, and it comes through in the pages of his memoirs.  From his eight-minute-long battle with a Jordanian Hunter (the longest one-on-one air battle in IAF history), to his recovery of an engineless Mirage fighter at low altitude, Ronen's career spanned the heyday of Israel's Air Force.  Anyone who follows this period of Israel's Air Force history will have come across Ronen's name, over and over again.  Giora Romm, Israel's first jet fighter ace, served under Ronen in the 119 Squadron during the Six Day War.  Menachem Shmul, who went on to be the lead test pilot at Israel Aircraft Industries, also served in the 119 Squadron in 1967.  Yiftach Spector, the commander of Israel's third Phantom squadron, attended one of Ran Ronen's training courses and wrote in praise of demanding methods.  Even Ezer Weizman, the Air Force Commander who transformed Israel's fighter fleet during the 1960s, speaks fondly of Ronen in his own memoirs.  Well written, with detailed descriptions of aerial encounters, Ronen's autobiography provides the back story to the most accomplished air force of the jet age.

Monday, July 20, 2015

Aircraft Performance - Part 1 - Video and PDF

Video edition of Part 1 of the Aircraft Performance Review.

Original chart pack is available below.

Aircraft Performance - Part 1: The Design Crossroads

The following is the first in a five-part series tracing how aircraft performance is calculated, and its relationship to the mission requirements for the aircraft.  This combination of metrics for performance and mission requirements go hand-in-hand throughout the early phases of the airplane design process.
Performance encompasses a broad series of design requirements, from take-off and landing distances, to cruise and maximum speeds, to turn rate and acceleration.  All of these metrics describe how an airplane will fly.

The mission requirements, on the other hand, define how far the airplane is expected to fly, and with what payload.  Both a 737 and a 747, for example, might have many performance metrics that are similar, from take-off distance to cruise speed.  Their range and payload requirements, however, are radically different.  Where these two sets of requirements meet - both the performance metrics and the mission requirements - will define how large the airplane will need to be.

Early in the airplane design process, during conceptual and even into preliminary design, the airplane's performance requirements will typically be portrayed in the form of a constraint diagram.  This diagram will plot the thrust loading, or thrust-to-weight ratio on the vertical axis, and the airplane's wing loading or the weight divided by the wing area on the horizontal axis.  On this diagram - for a given airplane configuration - the developer will plot lines that define the thrust loading and wing loading combinations that meet the minimum performance objectives laid out for that aircraft.  Collectively, these lines will identify the boundary for the solution space, defining all possible thrust loading and wing loading combinations that meet all of these performance objectives.

Within this solution space, the developer will typically down-select to the configuration with the minimum thrust-to-weight ratio, and the highest wing loading (minimum wing area) that satisfies all of the design criteria.  This is because the customer will seldom pay extra for additional performance that they did not require.  A larger engine or a larger wing would require additional raw materials to produce, driving up the unit cost with no appreciable increase in what the customer is willing to pay.  Moreover, if forced to choose between an airplane with a higher thrust-to-weight ratio (larger engine), and one with a lower wing loading (larger wing), the developer will usually gravitate towards the solution with the larger wing.  Pound-per-pound, adding wing area will be far less expensive than adding a larger engine.

Finally, the resulting design combination - the airplane's configuration, thrust-to-weight ratio, and wing loading - will be exercised in a simulated mission analysis to determine the size of the resulting aircraft.  As we will see in the following segments in coming weeks, this design effort will be an iterative process.

Sunday, July 19, 2015

Book Review: Israel's Best Defense

Eliezer Cohen
Israel's Best Defense
New York: Orion Books, 1993
Category: Israel Air Force - History

Rating: 4-Stars

It is tempting to compare Eliezer Cohen's history of the Israel Air Force with the similarly sized tome from Ehud Yonay - both of which came out in the same year.  Cohen's book similarly traces the history of the Israel Air Force from its inception in 1947, but covers a few more years in time - into the early1990s.  Cohen was himself an Israeli fighter pilot, and later a helicopter pilot, lending a certain degree of autobiography to sections of the book.

On the whole, however, Cohen's writing style lacks some of the polish of Ehud Yonay's prose - the difference between a pilot turned author and a professional journalist.  You can see Cohen's style and voice evolve and mature through the course of the book, and Israel's Best Defense clearly stands as an able compliment to Yonay's work.  Cohen knew many of the historic figures of the Heyl HaAvir first-hand - providing additional insights into critical personalities and into critical junctures in history.

So all told, an excellent history book.  Not quite as well polished as Yonay's historical text, but definitely worth adding to your library if you're an avid reader of air force history in the Middle East and elsewhere.

Saturday, July 18, 2015

Book Review: Aircraft Design: A Conceptual Approach

Daniel P. Raymer
Aircraft Design: A Conceptual Approach
Washington DC: American Institute of Aeronautics and Astronautics, 1989
Category: Aerospace Engineering

Rating: 5-Stars

Airplane design is an extremely broad topic, embodying many competing disciplines and spanning decades of learning - much of it earned the hard way: through tragic failure.  The young engineer therefore needs to start somewhere, and I know of no better introductory text than Daniel Raymer's Aircraft Design.

Daniel Raymer's book forms a worthy compliment to Jan Roskam's more expansive Airplane Design series.  While it doesn't have all of the calculations and formulae of Roskam's multi-volume set, Raymer's text is far more readable and accessible to the new engineer.  He also includes a number of subjects that Roskam omits, including approximation methods for drag rise and supersonic wave drag, as well as how to estimate drag rise due to external stores.

The chief advantage of this text, however, remains its readable prose.  While Roskam's more detailed works take time and patience to absorb, Raymer provides the concepts and outlines in a more friendly format.  The book does have its weaknesses.  Raymer's treatment of stability and control, as well as sizing methods for control surfaces, pales beside that of Roskam's volumes.  But for a new engineer intent on making a career in this industry, Raymer's book is the place to start.

Again, none of these books is aimed at the casual reader.  These are engineering texts.  But for someone with the right background, Raymer's work provides the starting point for the decades of professional learning that will follow throughout a career.

Friday, July 17, 2015

Book Review: Viper Pilot

Dan Hampton
Viper Pilot
New York: HarperCollins, 2012
Category: U.S. Air Force - Biography

Rating: 5-Stars

Dan Hampton was a U.S. Air Force fighter pilot from 1986 to 2006, flying the F-16 "Viper" in Wild Weasel squadrons during both the 1991 Gulf War and the 2003 invasion of Iraq.  For those not already aware, U.S. pilots have referred to the F-16 as the "Viper" since it first entered service in the latter 1970s, and the "Wild Weasel" squadrons are the units dedicated to hunting down and eliminating the surface-to-air missile batteries intended to shoot them down.  Awarded four Distinguished Flying Crosses and one Purple Heart, Hampton would retire as a Lt. Colonel, and one of the most decorated U.S. fighter pilots of the past twenty years.

Dan Hampton delivers the kind of in-the-cockpit memoir that comes along only once in a decade.  His accounts of life as a pilot, of the cocky self-assurance that is needed to strap yourself into a supersonic jet and fly towards, not away from missile batteries firing at you, is what brings the adhrenaline pumped world of fighter aviation to life.  Hampton was also a "patchwearer" - meaning that he was one of the select few pilots to pass the rigorous training regimen of the USAF's Fighter Weapons School (the Air Force's equivalent of the Navy's "Top Gun").  Only the very best pilots are selected to attend the full training program at Nellis - and many of those who do attend are washed out before completing the program.

In addition to being an exceptional, well-written book, Hampton's descriptions also highlight the evolution of the U.S. Wild Weasel fleet between the 1991 Gulf War and the 2003 Iraq War.  In 1991, the Wild Weasels were primarily tasked with suppressing enemy air defenses (SEAD) - utilizing radar-homing missiles to eliminate the missile tracking stations (or at least coax them to shut-down).  By 2003, the electronics and missile technology had evolved to the point where the Wild Weasels could focus on the destruction of enemy air defenses (DEAD), targeting the missile launchers themselves.

All told, one of the best first-hand pilot accounts out there.

Thursday, July 16, 2015

Book Review: No Margin for Error

Ehud Yonay
No Margin for Error
New York: Pantheon Books, 1993
Category: Israel Air Force - History

Rating: 5-Stars

There have been many history texts written about the Israel Air Force - the Heyl HaAvir.  Among them however, Ehud Yonay's work nonetheless stands out as a classic, sweeping tale.  What sets Yonay's book apart is the quality of the writing.  Israeli-born, educated in the United States, Ehud Yonay was the journalist who wrote the original "Top Gun" article for the California magazine in 1986, which became the inspiration for the hit motion picture by that same name.  In No Margin for Error, Yonay combined his exceptional writing talents with unprecedented access to the pilots and pioneers of the Israel Air Force - to produce a history of the Heyl HaAvir which captures the nuances and personalities of many of its pivotal leaders.

Yonay's book traces the history of the Israel Air Force from its beginnings as a ragtag band of foreign volunteers flying cast-off warplanes in 1947, to the early 1980s, flying some of the most advanced weapons platforms in the world.  Where Yonay most excels is in bringing life into the men of the IAF, and the battles in which they fought.  His vivid portrayals of Yak Nevo, Ezer Weizman, Moti Hod, and Beni Peled allow each to be brought to life across the pages of this book.  Over 60 interviews went into producing this unique text, a chronicle that provides the personal perspective that is so often lost in many history texts.  These kind of personal portraits, well crafted prose, as well as his direct access to many of the pivotal figures themselves (some of whom are no longer living), are the reasons why I put this book at the top of my Israel Air Force history list.

Wednesday, July 15, 2015

Book Review: Douglas A-4 Skyhawk

Jim Winchester
Douglas A-4 Skyhawk
Barnsley, UK: Pen & Sword Books, 2005
Category: Aviation History

Rating: 5-Stars

The A-4 Skyhawk was an exceptional airplane - the last great bequest of Douglas' chief attack aircraft designer, Ed Heinemann.  The A-4 exceeded its expectations in ways that no aircraft either before, or since has ever accomplished: delivering the required range and bombload at less than half of the U.S. Navy's weight requirement, and with a top speed that was 90 knots (170 km/h) faster.  Thirty five years after the first prototype flew, the Skyhawk would still be flying into battle - as part of the Free Kuwait Air Force in the 1991 Gulf War.

For an airplane of such an illustrious pedigree, it has therefore often been disappointing that so many of the histories written on this program have fallen short.  Jim Winchester's book at long last corrects for this.  Providing a combination of technical history and first hand accounts from both U.S. and foreign operators, Winchester's text provides the breadth and depth to place this historic little attack jet into its rightful place in history.

In addition to the finely crafted first hand accounts, the book adds serial number lists for Skyhawk deliveries, for each of the Skyhawk models, as well as tracing the units that they served in, and aircraft on display today.  The appendices further supplement this with statistics for each Skyhawk model.  A must-have for any Skyhawk enthusiast.

Tuesday, July 14, 2015

Book Review: Airplane Design

Jan Roskam
Airplane Design
Ottawa KS: Roskam Aviation and Engineering Corporation, 1989
Category: Aerospace Engineering

Rating: 5-Stars

Jan Roskam's eight-volume compendium of Airplane Design calculations stands out as the ultimate reference set for conceptual and preliminary design, combining airplane development experience spanning decades in time and across multiple manufacturers.  As a reference source for design calculations, it is without parallel.

Nowhere else is there an airplane design reference as comprehensive as this, representing a collection of design and analysis techniques in virtually every aspect of airplane design and dynamics.  The set is divided into eight volumes as follows:

Part I, Preliminary Sizing of Airplanes
Part II, Preliminary Configuration Design and Integration of the Propulsion System
Part III, Layout Design of Cockpit, Fuselage, Wing and Empennage: Cutaways and Inboard Profiles
Part IV, Layout Design of Landing Gear and Systems
Part V, Component Weight Estimation
Part VI, Preliminary Calculation of Aerodynamic, Thrust and Power Characteristics
Part VII, Determination of Stability, Control and Performance Characteristics: FAR and Military Requirements
Part VIII, Airplane Cost Estimation: Design, Development, Manufacturing and Operating

I was first introduced to this remarkable resources decades ago, when I was the teaching assistant for a senior-level Airplane Design class at the University of Michigan.  The first two volumes of this set formed the textbooks for our course.  The balance of the set was employed in the follow-on class (for which I was also the teaching assistant): Advanced Airplane Design.

Over the years, I have repeatedly referred back to these texts.  Particularly in the vital areas of Stability and Control, Jan Roskam's publications are a must-have for the serious engineer.  It's all here.  How to estimate take-off distance.  How to estimate weights.  Sizing control surfaces.  This is the design reference for the serious airplane engineer - not the casual reader.  This is not the type of book that you pick-up and read, as if it were some novel, or history of aviation.  These books are meant to be used.  It's when you put these volumes into practice that they become truly exceptional.

So, for the casual aviation reader, who likes to read about the history of aviation or perhaps about the latest technical trend: this is not the book for you.  For the engineering professional however, there is no other resource that can compare to the breadth and depth of Jan Roskam's collection.

Monday, July 13, 2015

Review of CSBA Study on Future Air Dominance - Video and PDF File

Video edition of independent review:

Original chart pack is available below:

Review of CSBA Study on Future Air Dominance

A study published this past April by the Center for Strategic and Budgetary Assessments raises some important questions about what the future of air combat, and air dominance holds in store.  The study projects forward to make recommendations for the next ten to fifteen years of defense spending, based around past and current trends.  Among the conclusions drawn by this study, and certainly the one that will draw the most attention, is the assertion that:
"An effective sixth-generation 'fighter' may look similar to a future 'bomber' and may even be a modified version of a bomber airframe or the same aircraft."
In other words, the study is suggesting that in the future, air combat maneuverability will become less important, and that a future fighter will need to carry lots of weapons and travel over long distances.

The CSBA study highlights a number of trends in air combat from the past half century, which bear repeating:
  • The key role of situational awareness
  • The transition from guns-only to missile-dominated engagements
  • The integration of hostile IFF (identify friend-or-foe) interrogation systems
  • The increasing role of AWACS in battlefield management
  • The emergence of infrared search and track systems (IRSTS)
The study also takes note of the growing concern surrounding the United States' force projection capabilities in the Far East, where there are relatively few friendly air bases and where the distances are much greater.

Proposed CSBA model for future air dominance (CSBA Graphic)
What the study proposes as a solution to this scenario, is a new air dominance model: one which relies on a combination of bomber-sized command and control centers and unmanned air vehicles.  It is assumed that both the command and control aircraft and the UAVs would be low-observable aircraft, and that they would be armed with beyond visual range missiles.  The study further suggests that in a future stealth-on-stealth engagement, where the opposing aircraft would likewise have some measure of low observable capability, that the principle sensor for detecting, tracking and firing upon an opponent would become infrared search and track systems (IRSTS).

Unfortunately there were a number of gaps in the data set from which the CSBA study drew its conclusions.  The study does not differentiate between BVR missile kills that were launched from beyond visual range, and those that were launched from within visual range.  In other words, just because it was a radar-guided missile that made the kill, that could have been launched from beyond visual range, does not necessarily mean that it was launched from beyond visual range.  The study also accepts at face value the air-to-air kill claims made during the Iran-Iraq war of the 1980s - failing to take into account the vast cultural differences in combat reporting between the West and the Middle East.  This is equivalent to accepting the reports of "Baghdad Bob" during the 2003 Iraq War as if they were gospel.

Fiberglass mockup hailed as a "fighter" by  Iranian
authorities in 2013 (Mashregh News)
The study takes at face value some 290 air-to-air kills from the Iran-Iraq war of the 1980s.  To put that into perspective, that's more than all of the other air-to-air kills, from all other air wars, in the 1980s, 90s, and 2000s - combined.  The study further credits the Iranian air force with "sixty-two kills by F-14 crews using AIM-54 Phoenix missiles."  These claims fly in the face of assessments from the U.S. Central Intelligence Agency which maintain that shortages in spare parts and coolant had rendered most of Iran's air-to-air missiles inoperative.  The CIA also reported that only three Iranian F-14 Tomcat pilots had actually completed the entire F-14 training syllabus prior to the outbreak of the Revolution, and further confirmed that Iraqi fighters were able to carry out repeated attacks on Iranian-bound oil tankers with no appreciable losses throughout the war.

Again, there is a fundamental difference in the accepted norms for reporting between Middle Eastern nations and the West.  It's akin to the fiberglass mock-up that was hailed as a "fighter" by Iranian authorities in 2013.  None of the official air-to-air kill claims made during the Iran-Iraq war can therefore be taken at face value.

There is credible data available regarding the air-to-air kills that are confirmed to have been made.  That data was assembled into a study for the U.S. Air Force by Col. James Burton in 1986, covering the period from 1960 to 1986.  That study confirmed the transition from a guns-only to a missile-dominated environment.  However, out of 2,014 air-to-air missile launches, and 407 successful missile kills, only four air-to-air victories could be credited to missiles launched from beyond visual range.

The reasons for this are closely tied to rules of engagement, and the requirements needed to prevent fratricide.  It's not enough to know that another aircraft does not respond to a friendly IFF signal.  You have to verify what that aircraft is before you are authorized to fire upon it.

The other credible, publicly available air combat data comes from the 1991 Gulf War.  This war marked a turning point in the use of beyond visual range air-to-air weapons.  This was the first war where the United States possessed aircraft - in the form of the F-15 Eagle - with the necessary hostile IFF capabilities to independently verify the identity of an opposing aircraft.  During the Gulf War, 16 out of 38 allied kills were made from beyond visual range - an unprecedented total.  That amounted to 42% of all allied kills.  However, this also meant that 58% of the kills were still made from within visual range.

The air dominance proposal presented by the CSBA report therefore has a number of gaps.  The proposal relies exclusively on beyond visual range intercept capabilities, which from the historical data, can be expected to fail the majority of the time.  The proposal also relies on infrared sensors to obtain a BVR intercept capability.  However, all of our existing BVR weapons are radar guided.  There is therefore no explanation as to how an LO-capable opponent would be engaged from beyond visual range without development of a new class of missile.

The proposal also relies on a fleet of unmanned interceptors.  So the underlying assumption is that the development and procurement cost for a manned bomber fleet, that would double as a command and control center, and for an unmanned combat air vehicle to accompany them, would be cheaper than the cost for developing a manned interceptor.  However, in order to have sufficient range to be useful, these unmanned aircraft would have to be as large as a long-range manned fighter.  From our Global Hawk experience, we know that there is no automatic cost reduction from the deployment of an unmanned air vehicle.

Northrop-Grumman Global Hawk (USAF)
Global Hawk was the first time that an unmanned aircraft was developed that was similar in size and role to conventional, manned aircraft.  All of the prior unmanned platforms were inexpensive largely because they were piston powered, and relatively short on range, speed, and payload.  The eventual acquisition cost for the Global Hawk came out to be 76% higher than was initially projected.  The U.S. Air Force would cut its Global Hawk procurement from 63 to 45 aircraft, and would actually mothball all of the Block 30 versions of the aircraft, as being more expensive to operate and less capable than the manned U-2 aircraft that they were intended to replace.  This confirms what prior cost models for aircraft development and procurement had already told us.  The principal contributors to aircraft cost are: empty weight, maximum speed, and the quantity produced.  For equivalent range, payload and cruise speed, the cost will be the same, whether manned or unmanned.

The key assumption of the CSBA study is that the vast majority of future air engagements will occur beyond visual range, with the study further pointing out that only 38% of the visual range engagements that did occur during the 1991 Gulf War involved "significant air combat maneuvering."  The study fails, however, to assess what attributes lead to a high kill probability for either a beyond visual range, or non-maneuvering within visual range engagement.

Studies into the dynamics of air combat do exist, however.  Most of the research in this field is no doubt classified, under contract to the U.S. or other air forces.  A number of pivotal studies were nonetheless publicly released in the early 1980s by Wolfgang Herbst - then director of advanced design at MBB (Messerschmitt-Bolkow-Blohm), the forerunner to Deutsche Aerospace and which today forms the German partner under the Eurofighter Typhoon.  Herbst's study assessed alternative attributes for future fighter concepts employing West German Luftwaffe pilots in simulated engagements.  These studies concluded that BVR combat was "characterized by very careful power management," as each aircraft maneuvered to bring their opponent within the kill envelope of its own weapons, while avoiding exposure to the lethal envelope of the opposing aircraft.  Of the projected future technologies explored, supercruise was identified as having the highest impact to the successful outcome of BVR engagements, with a kill-to-loss ratio of up to 8:1.  In essence, the study concluded that the aircraft with the advantage in excess energy would the aircraft that controlled the engagement - an outcome very similar to decades of experience with close-combat maneuvering engagements.

In conclusion, the CSBA study raises significant issues.  The future of U.S. air dominance is a vitally important subject that needs to be debated - both for budgetary reasons and for the sake of U.S. national security.  However, the CSBA study was also based on faulty data.  The majority of historical air-to-air kills, even in the 1991 Gulf War where the U.S. brought to bear all of the modern tools of airborne warning and command as well as hostile IFF interrogation, have occurred within visual range.  A strategy based exclusively on a beyond visual range intercept will fail the majority of the time.  The strategy proposed by the study also relies on a fleet of unmanned air vehicles, without taking into account the cost of developing such a system.  Further, the study also assumes a beyond visual range stealth-on-stealth intercept capability, without highlighting the need to develop a new class of missiles to make these intercepts possible.  Finally, studies into air combat dynamics have suggested that, even from beyond visual range, the advantage resides with the platform possessing superior excess energy.  This conclusion is fundamentally no different from decades of visual range air combat experience.


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