A father of the design and development of the F-16 explains the unique philosophy and processes used to bring the most popular fighter of the post-Vietnam era from an idea to a finished product. Listen in as Gen. Michael Loh speaks to Aviation Week's Steve Trimble.

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Transcript

Steve Trimble:

Welcome to Aviation Week's Check 6 podcast. I'm Steve Trimble, the Defense Editor of Aviation Week based in Washington D.C. We are recording this episode on the eve of the 50th anniversary of the first official flight of the F-16, which took place on February 2nd, 1974. Of course, those familiar with program's lore know that the unofficial first flight happened 13 days earlier on January 20th when test pilot Phil Oestricher saved the YF-16 prototype and possibly the entire program by taking off to avoid a crash during a high-speed test. We all know that the F-sixteen went on to become the most popular western fighter of the post Vietnam era, selling more than 4,500 aircraft to over 25 countries, and it remains in production today with a backlog of about 125 aircraft and Turkey just approved last week to buy even more. So we at Aviation Week's Check 6 podcast are honored today to talk about the history and the modern relevance of the Fighting Falcon with Air Force General Michael Loh, who retired in the mid 1990s after a long and very distinguished career.

After graduating from the Air Force Academy in 1960, he flew 204 combat missions in Vietnam and went on to become vice chief of staff for the Air Force in 1990 and then served as commander of Air Combat Command. But the reason we are talking to General Loh today is because it would be hard to find anyone who wore an Air Force uniform that deserves more credit for the program's success. Starting in the late 1960s, he worked with another Air Force officer, the famous John Boyd, on applying Boyd's energy maneuverability equation to the design requirements for a lightweight fighter, which of course became the YF-16 prototype. Loh then became the program manager for the Lightweight Fighter competition in August, 1973. After the YF-sixteen won that competition a then Lieutenant Colonel Loh became the project's director for the F-16 development program. So General Loh, thank you for joining us.

Michael Loh:

Oh, thank you for having me.

Steve Trimble:

Okay, so let's start way back at the beginning. It's in the mid 1960s. John Boyd has developed this energy maneuverability equation. So what is that equation and how did it help shape the design of that YF-16 prototype?

Michael Loh:

Well, that was a breakthrough in terms of the ability to measure fighter aircraft performance. And as you asked, the basic equation was a Ps of S, which is specific excess power. Specific excess power is equal to thrust minus drag times the aircraft velocity over its gross weight at that measurement. So it's Ps of S equals T minus D times V over W. and Ps of S is specific excess power. John Boyd developed that simple equation after he graduated from Georgia Tech and went down to Eglin as part of the Air Force Weapons Center down there teamed up with a fellow named Tom Christie, and he was able to generate Ps of S charts, specific excess power charts of any aircraft, friendly or enemy, as long as we had the drag pullers and the thrust and drag curves of that aircraft, which were not easy to get for a MiG-21 or a MiG-19.

So at any rate, so he developed a P-sub-S [equation].. But I was a fighter pilot at the time in the 33rd wing at Eglin young captain, and we were going to go to Vietnam within the next two years or so. And so John Boyd came over and briefed us, and I took a special interest in this and talked to him a long time, developed a relationship with him, but he was able to develop P-sub-S charts, specific excess power charts, for the F-4 and for the MiG-21, he got that out of the foreign technology division at Wright field, their drag polars and their thrust and drag curves. And so we were able to show on a simple comparison where the F-4D would be superior in performance over the MiG and where on the chart the MiG would be superior to the F-4, so we could avoid those parts of the flight envelope.

That simple story starts a relationship that I had with John Boyd that existed over the next 20 years. And so when I came back from Vietnam, I was at Da Nang Air Base, and from 1968 to October 1969 came back, I requested an assignment to the Pentagon to be with John Boyd because he had moved up to the Air Force fighter requirement shop in the Pentagon. So I joined up with him and he was at the time, trying to advance his energy maneuverability theory as a design tool for new fighter aircraft. At that time, which was 1969, 1970, the F-15 aircraft was just under contract. Cost growth, cost was increasing on the F-15. Boyd said, "I've got a better idea, we can build another fighter." Of course, the Air Force didn't want to hear that we could build another fighter based on EM theory. And so he started a small group of people in the Pentagon based in the Pentagon to advance his EM theory as a basis for a new fighter.

And at the time, he was able to generate out of Wright field a $50,000 study, very nondescript, innocent sounding study that said the title of it was using Energy Maneuverability Theory for the Design of Fighter Aircraft … nobody noticed this study. It went out to industry. Industry got excited because Boyd and I and others were out talking to Lockheed and GD and LTV and Northrop about this concept and how to design a new fighter, everybody but McDonnell Douglas, because they were the contractor for the F-15, and they didn't want any part of anything that smacked of competition or a threat to the F-15. Anyway, more on that later. Do you want to ask another question? Did you want me to keep talking, Steve?

Steve Trimble:

No, no. I mean this is a perfect history of it, but I mean that was the key issue is you've got the F-15 and the F-16 moving forward. And as I understand it, you had OSD get involved with the launch of a lightweight fighter prototyping program.

Michael Loh:

The breakthrough at that time, and this was 1971, early '71, the breakthrough was when David Packard, CEO of Hewlett Packard was serving a two-year voluntary assignment as the Deputy Secretary of Defense, and David Packard said, "I'm tired of looking at these paper proposals for major weapons systems. I want to do some prototyping. I want to fly before buy." And that's where the expression fly before buy came up, with David Packard in the Pentagon in 1970, '71, and he said, "So I'm going to have a little study. We're going to show the advantages of prototyping and pick a couple of programs to prototype." Well, that's when Boyd and I leaped into action. We, and Christie, and Pierre Sprey, and everybody jumped at Packard and said, "Hey, we've got the program you ought to use for this." There was a lot of reasons for that. So because we knew we weren't going to get anywhere with the Air Force, and so if we had some stimulus from another outside agency, and Packard was terrific on this, he said, "Okay, let's do this."

So when his study was released, it had two projects in it, the Lightweight Fighter Project and the Advanced Medium STOL Transport Project, both for prototyping, competitive prototyping. Competition was to be a big part of it, competitive prototyping. So we leaped off then that was a breakthrough to get the Lightweight Fighter as a prototype program, and that was a breakthrough. So we were off and running with a funded study to do the prototypes on the YF-16 and YF-17. Now, we picked those contractors at that time through a source election from the Pentagon with a simple RFP based on energy maneuverability, and I was a part of that source election, and we had five contractors and we picked GD and Northrop. We had a simple RFP, which emphasized performance in the air combat arena, which was where P-sub-S, where we fight in air combat. It wasn't out at Mach 2. It wasn't real slow. It was in the heart of the envelope.

Steve Trimble:

And there was one other final, and as I read the history of it, I was surprised to learn that Boeing came out first in the initial analysis. Is that right? And it looked a lot like the F-16 without the blended wing body.

Michael Loh:

Boeing submitted a very responsive proposal from the standpoint of performance and capabilities, and it did look a lot like the YF-16. The problem with Boeing was that it was too little, it was too small. You had to be a small pilot, you had to be a jockey in order to fit into the cockpit. So it was very high risk. When we evaluated them, Boeing came out number five in terms of risk, although they were number one in terms of gross performance, GD and Northrop were both ranked very high. Lockheed, we went and visited each of the contractors, and when we visited Lockheed, Kelly Johnson, of course, was their designer of [inaudible 00:09:16].

Steve Trimble:

Founder Of the Skunk Works. Yeah.

Michael Loh:

We went to the Skunk Works. He didn't like our RFP. He said, "You got the wrong airplane. What you really want is a Mach 2, Mach 2.5 fighter that can get there the fastest and shoot down whatever's out there." And he even proposed that to the Pentagon in competition to the F-15, about a year earlier, he got thrown out. Well, now he got thrown out of us because he wasn't reading what we wanted. We wanted a highly maneuverable fighter in the air combat arena, which was from 0.6 to 1.6 Mach number, up to 35,000 feet. That's where we wanted the maximum performance. So we picked those two and off we were running with a prototype. Now, can I keep talking?

Steve Trimble:

Oh, sure. And then the other big design requirement was a 19,000 pound maximum weight ceiling. Was that-

Michael Loh:

It was 19 or 20,000. I'm not sure what it was. Yeah, it was right around there. We were trying to put a lid on the weight. We didn't want to specify weight, but we wanted to ensure that we were talking about a small fighter. And when we got picked to do the prototype, this was important for several reasons. One, that we were a threat to the F-15, and the F-15, and the Senior Air Force leadership didn't want anything to do with the lightweight fighter. We had a fighter underground going on, not the so-called Fighter Mafia everyone talks about, it was only in the Pentagon. I had a lot of friends out in tactical air command that were rooting for a lightweight fighter. And so there were a lot of others, Boyd and I were still the major guys in the Pentagon promoting this.

But one reason that we needed to have a flying prototype, Steve, was because we had to shoot down several myths. One, [because] GD was an all fly-by-wire airplane. It had no mechanical backup for the flight control system. This was unheard of at the time. We had other airplanes like the F-15, the F-111. They had parts of fly-by-wire, they had electronic boost and some things like that, but they always had a mechanical backup and a redundant mechanical backup. And so it was unthinkable at the time by anybody who knew what they were talking about at the current state of the art that you couldn't trust a totally fly-by-wire flight control system without a mechanical backup. GD had a totally electronic fly-by-wire system without a mechanical backup. And the reason it was important was not just because it was electronic, but it saved a lot of weight, more than you would appreciate not just the mechanics of the mechanical backup, but if you look at an F-15, for example, it carries 600 pounds of ballast up in the nose in order to keep the center of gravity forward of the center of pressure, so it maintains static stability.

So you have to have that with the mechanical system of the fly-by-wire. You can adjust the flight controls, elevators, and rudder, and ailerons in order to maintain artificial stability even when you're statically unstable by the distribution of your gross weight. And then there was other weight savings as well, by having an all fly-by-wire system. The other reason, which I mentioned in the letter, the other reason was we wanted to shoot down the theory that small airplanes couldn't go very far, that the range was going to be very low range. We had the T-38, and the F-5 were flying, and they were short-legged fighters. They couldn't do a good fighter mission that we would have to do worldwide. So there was this theory running around, especially brought on by the F-15 crowd that, "Hey, these lightweight fighters can't go anywhere. They're too small."

Well, actually, as we know, the range is not determined by the quantity of fuel in the airplane. Your range of radius is determined by the fraction of the gross weight that is fuel quantity over total gross weight. And when you look at F-16 versus F-15, the F-16 actually had a higher fuel fraction than the F-15 on internal fuel only. So we were able to, by flying the prototypes, we were able to overturn the opposition because it was all fly-by-wire and overturn the opposition because it was too small to go very far.

The third breakthrough with the prototypes was the miniaturization of electronics, at this time. This was the mid '70s, and now we were getting into T/R modules for radars. We were getting into miniaturization. Solid state was coming in for electronics, and you could package a whole lot of electronics into a small airplane.

And we started that, and we did that. And the radar was a T/R module radar. Well, initially it was a full aperture radar, but then it developed. And so every time we had a technical breakthrough in terms of electronics or sensors, it was put into the F-16 and F-17. So we were able to put a package, a lot of power and capability electronically for weapons and electronic warfare and other things that were unthinkable for airplanes before that. So the breakthrough of flying that prototype was terrific. So then, go ahead. I'll let you talk now.

Steve Trimble:

And as I understand, you get to the first flight of the YF-16 on February 2nd, 1974. A month later, YF-17 the Northrop aircraft, which eventually becomes the Boeing F-18, but that's a longer story outside of this podcast. They fly in March, and then something big happens in April when Deputy Secretary Packard comes out and says, this is not just going to be prototyping. This is going to be a, "Whoever wins this competition is going to go into full production."

Michael Loh:

Okay, so let me get into that. So we selected the YF-16 and YF-17 to build two prototypes each and fly them. In the meantime, I go off to MIT and get a degree, advanced degree in aeronautical engineering, and then go out to the program office where I become the project's man and manager for the Lightweight Fighter program. And yes, we had the first flight, the first flight occurred, at the end of January '74, and Phil Oestricher was doing a high-speed taxi test, but down the runway, he was going up to just before liftoff speed and then abort to show that we had sufficient braking and sufficient capability on the ground. And sure enough, the airplane took off. So anyway, that's the story itself, as you know, and that's been advertised a lot. But here's what happened. So in '74 starting in January, February of '74, when after the airplane flew, the cost growth of the F-16 was growing, F-14, also F-14, F-15 cost growth was very high.

And the Air Force was not going to be able to reach its goal in terms of tactical fighter wings, number of tactical fighter wings to deal with the threat. So F-15 was going to cost too much, and we weren't going to be able to buy enough of F-15s and other fighters to fill the force structure required against the threat scenario. So the second breakthrough was Secretary of Defense Schlesinger. Jim Schlesinger was now the Secretary of Defense, and he said that he became a convert of the lightweight fighter while the lightweight fighter was starting to fly. He was enamored by the F-16s and F-17s that were flying. Of course, several of the guys in OSD got to him and Boeing got to him. And so the second breakthrough was when he said, "I'll cut a deal with the Air Force chief of staff," who was general David Jones at the time.

And he said, "Let's cut a deal. General Jones, if I will give you all your full quantity of F-15s that you want, 750 F-15s, I'll give you 750 if you'll allow the rest of the force structure to be filled up with the winner of the F-16, F-17 competition so that we can get your 26 tactical fighter wing equivalents. You can get all the F-15s you want, and we'll fill it up with the rest of it." And David Jones says, "That is a good deal, I accept." And he called it the high-low mix. And that became the high-low mix. We've got a smaller quantity of high-performance fighters, the F-15, which they consider high-performance complemented by much larger quantity of lower capability, that they thought lower capability, and we'll get 26 tech fighter ones. That was the breakthrough. That was when the Air Force accepted the airplane, and that is when the air combat fight, it went from lightweight fighter to air combat fighter.

That became the program of record because now we were into the budget for the F-16s. So that was a big breakthrough right there in 1974. So then we formed a SPO after that. Okay, now you've got to get a SPO. You've got to, you've conduct a source selection. We were already working on the source selection criteria between the YF-16 and the YF-17, and you've got to get a whole program put together. And so that's what I was doing. I was missionizing, missionizing these airplanes. I was saying, "Take these prototypes that had no capability for war fighting in them or air combat fighting and let's see what we can put in them, a radar, electronic warfare, avionics, weapons. Where are the sidewinders going?" So that's what I was doing while the YF-16s and YF-17s were flying and while we were writing an RFP for the final source selection.

Steve Trimble:

And the thing that we write about constantly in current procurement and development is the challenge of just keeping aircraft requirements, just requirements creep, configuration creep. How did you look at maintaining discipline on the original requirements and the baseline configuration?

Michael Loh:

Okay, so let me get back with it. So we had all the prototype data in to support the source selection in January, 1975. The source selection was complete, and I was the one who briefed new Air Force Secretary McLucas, John McLucas, secretary of the Air Force at the time. And I briefed him and everybody who knew anything about Air Force and aviation was in that meeting, that source selection meeting. And McLucas picked the F-16, and now we had development underway. Then the Europeans came in. They wanted to buy some of these, and I was the chairman of the operational subcommittee. But what you're asking now is how did we keep cost and weight discipline in the program? Because as soon as the F-16 was picked for the Air Force Air Combat fighter, everybody who had a system, a widget, an idea from the laboratories, from industry, from DARPA, everybody wanted to come in and put their widget on the F-16.

So I was inundated with all this. "Oh, you got to have my system in there." [inaudible 00:20:26] Not unlike today, same thing today. So anyway, I went to the Pentagon, said, "I need some help." And the chief of staff said General Alton Slay, who was the director, DCS requirements at the time, two-star shop I was originally in when I started all this, he formed the Configuration Steering Group, CSG. The Configuration Steering group, met every three or four months to make a judgment on whether or not somebody's idea or somebody's system or some technology or an upgrade to an existing technology that was on the airplane, was ready to get it into the year to fight its way on the F-16. And we had ironclad discipline because all these ideas came to me in the program office. I would do a cost-benefit analysis on them and a threat analysis and do all that operational research on them myself, get with General Slay even before the meeting and say, "Here's what's on the agenda. We want to put more improved radar on there. We want to put the highly advanced EW processor on there."

And I would tell him the outcome of our cost-benefit analysis, and then we'd have the meeting. And Slay was iron. I mean, he was iron-fisted, iron. We exercised ironclad distal. We just said, "No, there is not one idea during that development program that found its way into the F-16, other than maybe an upgrade to a system that was already going on the airplane and had low risk." So that's what we have lost, Steve. Everyone wanted to sell their system in widget and Slay just said, "No," just said "No," over. [inaudible 00:22:12] Go ahead.

Steve Trimble:

Well, it seems like there was an ethos there that you didn't have to put everything possible on the aircraft to make it most effective against the highest threat and use tactics and perhaps skills-

Michael Loh:

Numbers, numbers, numbers.

Steve Trimble:

And numbers, yes, to offset any deficiency in absolute technologies.

Michael Loh:

To depart a little bit, that's the way we fly and fight. We don't put all systems on one airplane. I do not believe in one versus one analysis that you're always going up against the worst case threat every time in every airplane you send up has to be able to defeat the most advanced fighter that the threat might put up against you. Now, we had an F-16, which was much simpler. We could have put a lot more capabilities. It probably would've cost too much, and we wouldn't have gotten as many airplanes. But we said, "We're going to compensate for the difference between us and an F-15 in air to air combat with numbers. Instead of sending up two airplanes or four airplanes, we're going to send up 40 airplanes. We're going to saturate the sky with numbers, which was a good, and therefore, that's the way we ought to look at requirements for fighter aircraft is you don't have to put all of the capability."

That's the problem, in my opinion, with the F-35, maybe a problem with the B-21, but it's clearly a problem with the F-35. They tried to cram everything they could into every F-35, and they should have gone like we did with a basic bare bones baseline like we did with the F-16A Block 5, and then incrementally improve it over time as the systems that you want to incorporate the risk is reduced and they become affordable and we can put them on. That was the genesis of the MSTIP program. The Multi-stage Improvement Program for the F-16 was based on that theory, that we're not going to put anything on this airplane until it's been fully tested, fully costed. We understand the cost, we understand what it adds to the capability of the aircraft, and then we'll decide to put it on there. That started with the configuration steering group, and then we finished, we followed through on that with the Multi-stage Improvement Program. And that's about when I left the program in 1977.

Steve Trimble:

And then I'm curious, this skips forward a little bit, but then there were some alternative designs of the F-16 proposed over the next several decades, starting with the F-16 XL to replace F-111, which eventually of course was won by the F-15E. There was a twin tail that, I think it was the F-16 plus plus or something Super F, Super Falcon concept in the early 1990s, maybe to offset the F-22, if that was going the way of the F-15 back in the early '70s. And then there was the proposal of taking the Block 60 that the UAE eventually funded and buying more of those for the US Air Force. And as you looked at all those things, I mean, what did you think about them?

Michael Loh:

The F-16 XL was a bad idea for the F-16. They were trying to put a bigger wing to be able to have the extended range and weapons capability, the payload of the F-15E and it was non-competitive. They flew it, but I was never a fan of the F-16 XL, the F-15E was the right way to go there. So throw that out. Then the other variants that came up was just a way for general dynamics, which then became lucky to compete in what other people thought might be a good idea, but none of them would take it seriously, none whatsoever. Now, you mentioned the Block 60 that the UAE funded, and that is an excellent airplane, and we should buy it. And I don't know what the Block 70 is right now, but it may be the block 50, 60 that has the US invention in it.

But clearly, clearly the UAE have bought a wonderful airplane that the Air Force could benefit from by buying it and buying in quantity. And I think this notion that the F-16 has seen this last days is wrong. It's dead wrong because a modern Block F-16 is as capable as any fighter in the world right now. It only lacks one thing, and that is deep stealth doesn't have the on-board natural stealth that an F-35 has or an F-22 has, but in every other capacity, every other thing, the F-16 Block XX, whatever it is as capable as anyone else got. New engines, new avionics, new systems, new weapons, and the miniaturization of weapons has helped with the payload capability, the F-16. So in my opinion, the F-16 life is far from over right now. Although some would want to say that the F-35 is going to replace F-16s. I don't think you'll ever get the F-35 at a cost that you can buy them in any large quantities. And it's been a shame because we should have exercised the iron discipline we had in the F-16 program. We should have put that into the F-35 program like we did with the F-16, and we failed to do that.

Steve Trimble:

And also, just as you're talking about the relevance both today and the future, obviously right now the F-16 is becoming the frontline fighter for Ukraine. It already is for that in Taiwan two of the really big hotspots. But then as you look into the future, we see next generation air dominance and the sixth generation fighter. There's collaborative combat aircraft and whatever that turns out to be, there's of course all the F-35s out there. So what is the role of an F-16 in that kind of force, actually talking about US Air Force type force design and force structure. But what does the F-16 do that the others aren't doing already?

Michael Loh:

Well, it exists. It exists. NGAD is a paper airplane, CCA or paper drones and anything beyond that's on paper. I mean, I read about NGAD as though it were a finished product, and it's not. I don't even know what NGAD is. See, we have a breakdown in the requirements process right now where the operator doesn't have a strong enough voice against the technocrats in order to define a system like we had. And I did when I was in TAC and RDQ way back when. So you got to break down in the requirements process because the operator doesn't have a strong enough voice, and you've got an NGAD that I don't know what it's going to cost. But I'll tell you what, there's no discipline. There doesn't seem to be any discipline in that program because nobody can define it, and everybody will want their widget and their new technology in it.

So I'm glad that we have F-35s in production and F-16 in production because we may need both of them for a long, long time before any of these other notions come into being. So I'm not being facetious about all this, but NGAD to me is a paper design of something and I don't know what it is. And I don't think Secretary Kendall knows what it is or anybody else in the Air Force hierarchy knows what the NGAD is, and they ought to be writing it down, what's in it, what's not in it, what is it going to do, what are the requirements, and then get some discipline in the program. I don't see any discipline in any of those programs right now. I worry about the B-21. I mean, we've had a huge overrun, which we all expected, but I'm not so sure the production cost of a B-21 is going to be affordable in the quantities we need [for] long range nuclear and conventional bombers. And so again, I come back to the need for cost discipline, performance discipline. And like you and I both said, you don't need every airplane to have the ultimate capability in it because you can compensate with numbers and tactics. Over.

Steve Trimble:

Well, I think that's a lot to think about. And it's been fascinating to go back into that program and the history and just how relevant some of the lessons and the issues that came up are still today. But that's probably all the time we've got for today. I really want to thank General Loh for coming on and providing his insights, amazing insights over his career, and also special thanks to our podcast producer in southern Ohio Andrea Copley-Smith.

And don't miss the next episode by subscribing to Check 6 in your podcast app of choice. And one last request, if you're listening to us in Apple Podcasts and want to support this podcast, please leave us a star rating or a review. So bye for now. Thank you very much.