A funny thing happened on the way to 2030, what everyone thought the US Air Force fighter force makeup was going to be changed. In a big way. In particular, the long standing position that all fighter/attack aircraft had to be (seriously) stealthy has crumbled. One could try to address this by answering each “Why is the USAF doing X” or “Does that mean the F-35 sucks” or a hundred other questions individually, or with a broader narrative. I decided to pursue the broader narrative. Which means this is going to be long.
The first thing to keep in mind is that defense programs tend to have long life spans. I always think of it as 10+ years of technology development, 10+ years of product development, 10+ years of production, and 10+ years of sustainment. The “+” is important since each of these 4 phases can last a lot longer than 10 years, but they almost never take less than 10. So this gives you a minimum 40 year lifecycle for a weapon system. At the same time as you are doing that research work you are trying to figure out the threat environment for the program’s lifecycle. So again you are forecasting 30-40 years, or more, into the future. How much has the world changed in the last 40 years? A lot. The Cold War ended. Which is a huge wow from a defense standpoint. Just 20 years ago we were at peace, friendly with Russia, and on a really friendly growth path with China. We had some terrorism concerns, but these were definitely things short of war. But in a few months we will arrive at the 20 year anniversary of 9/11 and 20 years of war against terrorist groups and nations that supported them. Orthogonal to that Russia and China have risen to be major threats again. On the technology front we all know how much has changed. 40 years ago people didn’t have PCs and computer networks were in their infancy. 20 years ago the Internet was in its toddler phase, only some of us had cell phones, and they were just phones. Drones were things the military used for target practice. Etc. Tech was primitive. And so was defense tech relative to what we know today.
The F-35 program has its roots in a program the US Marines worked with DARPA on starting in 1983 to look at a successor to the AV-8B Harrier (which had just entered service). So conceptually it goes back almost 40 years. Then the US Air Force also started a program to look at what should come after the F-16. And the US Navy, well they were still smarting from the cancellation of the A-12 and were back to trying to figure out how to obtain a stealthy strike aircraft. But the Cold War had ended sending ripples through all these programs. Aircraft were used less, and wearing out more slowly. The threat environment abated of course, taking some of the pressure off to stay ahead of potential adversaries. And defense budgets were cut dramatically. So in 1993 these separate efforts were merged into the Joint Advanced Strike Technology program. It was renamed to JSF in 1995. So as we sit here in 2021 and ponder the F-35, what we have is the world’s most advanced fighter aircraft that is also based on a view of warfare, future threats, and technology that is over 25 years old. Certainly that view saw tweaks before the final product definition for the F-35 was locked down, but even those tweaks are 20 years old now. That’s one reason rolling out the so-called Block IV changes have become so important. They update the F-35 to incorporate much more of what has changed in the last 20 years than could be done during its elongated development process. But the important thing to keep in mind is that the vision around the F-35 is a 20-40 year old vision, and not everything about that vision stood the test of time or march of technology.
First up in discussing the Air Force’s apparent change of position on stealth is to think of what they were trying to accomplish with an all stealth fleet. Stealth is not something you need for every mission, but the number of missions where it is required started to break the “first days of war” model that was in place in the late 80s and 90s. In that model you used a small number of specialized stealth aircraft (e.g., F-117), along with Navy ship/sub and Air Force strategic bomber launched cruise missiles, to severely degrade an adversaries integrated air defense network and command and control systems. Within days those were ineffective enough that you could use your non-stealthy aircraft to continue the strikes. The problem was, as sophisticated air defense systems proliferate the number of specialized stealth aircraft and their geographic positioning become issues. You will have heavily defended targets where it takes weeks or months before you can degrade their defenses. So the Air Force went in a different direction. If every aircraft was potentially stealthy, you could make the decision on a mission by mission basis on how stealthy it had to be. Going into an area where air defenses are minimal, hang as much ordinance as you want off the aircraft and don’t worry about stealth. Need to worry about heavy air defenses in another mission? Just use internal ordnance. So you shift the stealth decision from “Do we have any F-117s in the area that are available” to “What weapons should we load up each aircraft with today”. That’s a huge benefit, and one that works for everything from a peer state adversary to a regional adversary to we are going up against a terrorist group that is getting support from a state-level adversary with air defense weapons in the vicinity. So on that level, all aircraft are stealth aircraft makes sense.
Second up is to think about the weapons of the late 80s and early 90s when these decisions were made. Although we are very used to precision guided munitions, glide bombs, and cruise missiles today that was all pretty new stuff back when these decisions were made. Cruise Missiles, for example, were just on ships and large strategic bombers. And they weren’t capable of hitting moving (e.g., tanks) or relocatable targets (e.g., ballistic missile transporter erectors). Laser-guided bombs were available, but had to be released at short range (just a few miles). Laser-guided missiles were also available, but again range was only about a dozen miles. Even JDAM GPS/INS guided bombs were a few years away, and like cruise missiles only useful against fixed targets. Oh, and their range wasn’t much better than the Paveway and Maverick laser guided weapons already in inventory. Basically the idea of standoff weapons in the mid-90s was that 4th generation fighters could stay out of the way of Short-Range Air Defenses, but they were very vulnerable to medium range air defenses. And those were proliferating. A stealth aircraft could evade both long and medium range air defenses to safely close within range to use a Paveway Laser Guided Bomb (LGB) or a JDAM. The U.S. would also start work on longer range standoff weapons, such as the JSOW glide bomb and JASSM cruise missile (which unlike earlier cruise missiles was slated to be carried on larger fighter aircraft). But even though JSOW could be released at the fringes of a medium range air defense system, overlapping air defenses still leave 4th generation fighters vulnerable. And even JASSM, with its 200 mile range, doesn’t sufficiently shield aircraft from longer range air defense systems. In their original form, the form that was under development when F-35 decisions were made, JSOW and JASSM could not deal with moving or relocatable targets. For that you had to fly in and locate the target, then illuminate it with a laser and use a LGB, or other laser guided munition, to engage it. So even knowing that longer range standoff weapons were in the offing, stealth was still a key feature for any new aircraft.
Third is to talk about some cost factors. With weapons like LGBs and JDAMs you are looking at under $50,000 per weapons. In some cases half that. With cruise missiles you are looking at $1M and up. Glide bombs are somewhere in the middle, with those just capable of hitting fixed targets costing little more than a JDAM. When it comes to moving targets things get far more complicated. A simple laser guided glide bomb isn’t going to cost much beyond a JDAM, but requires the launch aircraft to be within range of medium range air defense missiles while it illuminates the target. When you add in alternative, autonomous, terminal guidance (imaging infrared or millimeter wave radar) costs soar and the glide bomb can approach cruise missile costs. Cost matters, as anyone who watches the ups and downs of U.S. (and other countries’) defense budgets can testify to. You are never going to afford enough cruise missiles to attack all necessary targets, you are going to have to use lower cost weapons for most targets. And back in the 1990s it was pretty clear you could only afford to use cruise missiles for the highest value targets. For everything else you would have to get in close with an aircraft and use standoff weapons with modest range and low cost guidance. And that means having to evade medium range air defenses.
Up until this point it should be clear why you want a stealth fighter, and why every fighter a stealth fighter makes sense. Of course the F-35 isn’t just a stealth fighter, it is a combination of all the latest and greatest technologies in one aircraft. For example, the F-35’s EOTS system combines the functions of a Targeting Pod and an IRST and is built into the aircraft. For an F-16, F-15, or F-18 these are pods that you swap out depending on mission. Air Superiority? Put a Legion IRST Pod on the F-16. Ground Attack? Instead of the Legion you throw a Lantirn, Sniper, or LITENING pod on it but lose the IRST capability. And while Rafale also has an integrated targeting/IRST capability, the F-35 goes further with its DAS system. That’s 6 IR sensors around the fuselage that gives it 360 degree situational awareness. There is a lot more there as well, just want to go into this saying the F-35 is an amazing aircraft. Even if you doubt that, just take it as an assumption for the rest of this.
Now of course the F-35 has its downsides. Although the purchase cost is now down to the same amount as a 4th generation aircraft (particularly when avionics, targeting pods, etc. are included), the cost per flight hour are way too high compared to other fighters. While this is supposed to be brought under control by 2025, there are skeptics of course. Then there are supply chain problems that make it difficult to increase production rates, not to mention holds readiness rates down when spare parts aren’t available. But these are short term concerns when you are talking about an aircraft that is early in its production life. They do impact short term decision making, but should be secondary factors in overall fleet mix discussions.
So it’s 2021, and a lot has changed. Certainly much of what fleet planners and defense analysts projected back in 1995 has come true. So called Area Denial/Anti-Access environments validate most of their fears. What they less anticipated was how other offensive technologies would change heading into the 2030s. And it is those changes that bring the “every fighter a stealth fighter” requirement into question. Before I go into that let’s set one more baseline. There are sets of missions that a fighter/attack aircraft might seek to fulfill, and within each mission there are numerous scenarios. We used to buy separate aircraft for each mission, or even for subsets of the scenarios within those missions. We had fighters, interceptors, light attack, all-weather attack, close air support, long range strike/tactical bombers, etc. Over time we were able to merge these missions into a small set of aircraft types. The multi-mission fighter/attack aircraft became the norm. And the F-35 is peak multi-mission. So one of the questions that you need to ask when evaluating fleet composition is simply “is a single type the right solution for all missions or could some missions be better served with other types”.
Multi-mission vs. single mission has already been answered in at least one case. While a case can be made that the F-35 (and particularly the F-35B) is a fine close air support aircraft, we’ve decided to retain the A-10 to fulfill at least the core of that mission. In reality every aircraft at our disposal has been used for close air support over the last two decades. Including the B-1 bomber. But for those cases where “low and slow” still make sense, nothing is going to beat an A-10.
How about the decision to replace the remaining F-15Cs with the F-15EX, rather than the F-35 (or staying on the original plan of waiting for a next generation air superiority fighter to replace the F-15C)? Now things get interesting, and first off lets talk about things that have changed and are changing since the every fighter a stealth fighter strategy came into play.
We need to talk about Drones, Cruise Missiles, and Standoff Weapons. Back in 1995 the vision of a Drone/UAV/RPV was as either target drones or as an ISR (Intelligence, Surveillance, Reconnaissance) asset. It wasn’t until post-9/11 that the Hellfire missile was jury-rigged onto a Predator RPV (Remotely Piloted Vehicle). The Reaper, which replaced the Predator, is much larger and can carry a variety of weapons. It started out as a civilian project (for a cellphone communications relay system), but the military saw it and realized it would make a great Predator replacement. While we had a hint of the future in the 90s when the IAI Harpy loitering munition, nee “suicide drone”, appears as an anti-radiation weapon it wasn’t until a more general purpose version (Harop) appeared about 2005 that things really began to change. Still it is only within the last half-dozen year or so that we’ve seen an explosion of armed drones, loitering munitions, consumer-grade drones modified to drop small weapons, swarming drones to overwhelm defenses, etc. We are still at the beginning of this trend. Likewise we’ve gone from long range cruise missiles being a U.S. only capability carried by large aircraft to being a threat to the U.S. itself. A great deal of U.S. effort these days is in figuring out how to stop saturation cruise missile attacks and deal with the wide variety of armed drones that are proliferating. That’s on the defensive side. On the offensive side, new types of drones and cruise missiles represent an opportunity for the U.S. The last factor is the growth in standoff weaponry.
In a major conflict there are going to be hundreds of thousands of targets that need to be engaged. Back in the 90s or early 2000s the U.S. could only have enough cruise missiles to engage hundreds of targets. Glide weapons weren’t yet in operation. But today standoff weapons are being acquired in large quantities. SDB and Stormbreaker, JSOW C/C1, JASSM-ER, upcoming weapons like JSOW-ER and JASSM-XR, etc. Many of these have autonomous moving and relocatable target terminal guidance. Cruise missiles can now be used to engage thousands of targets, 10s of thousands with glide bombs. While non-stealthy aircraft are still at danger from long range air defense systems, they can launch weapons from beyond short and (most) medium range air defenses. These weapons give new capabilities to the F-35, but also expand the set of scenarios where a 4th generation aircraft can be successful. And then there are hypersonic weapons. More on this later.
Now we can really start to delve into the U.S. backing away from the “all fighters are stealth fighters” strategy. Let’s start with the purchase of the F-15EX to replace the F-15C. When the air force announced this strategy there was a lot of pushback of the “why not the F-35” form. Going back to the point that there are various missions, the F-15C is primarily used for North American Air Defense. The Air National Guard also uses the F-16 for North American Air Defense. A few F-22s are used in that role as well. But the observation here is that hundreds of fighter aircraft are used for North American Air Defense, and for the most part they don’t need stealth. Their primary mission is shooting down large numbers of cruise missiles launched at the U.S., not at all something where stealth would help. In fact weapons like the APKWS laser guided rocket are being tested for cruise missile defense, a weapon not compatible with being carried inside a stealth aircraft’s weapons bay. And so capability and cost for a very narrow mission set made the F-15EX along with F-16 upgrades very attractive. There is now talk of new purchase F-16s, or even more recently maybe a new build 4th generation fighter. New F-16s probably follows the rationale of the F-15EX purchase. The F-15Cs were so old and worn out that maintenance costs quickly exceeded replacement cost. The F-15EX is a really easy way to replace the F-15C; minimal retraining and other costs. And you get a major upgrade to the F-15 as a result. I assume the original “new F-16s” falls into the same arena. We are upgrading existing F-16s, but they are worn out. Buying new ones in the latest configuration makes more economic sense. Again for missions where the F-35s unique capabilities aren’t needed. Both buys avoid the F-35 supply chain and cost per flight hour problems. The F-15EX also keeps the U.S. manufacturing base healthy by maintaining a second major airframe supplier.
The recent revelation that the Air Force might actually develop a new 4th generation F-16 like fighter is more interesting. Isn’t that likely to bring with it some of the same problems as with the F-35? Development costs. Creation of a new supply chain. Going through a maturization process. Extensive re-training? Etc. Why do this? Also, there is more chatter on replacing the existing F-15Es with the F-15EX is picking up. Why?
I’ve talked about missions that don’t require stealth. I’ve talked about the growth in standoff weapons. I’ve mentioned hypersonic weapons so let’s talk about that next. With great speed and range comes great size and weight. A long range (1000nm+) hypersonic cruise missile is probably too big and heavy to carry on the hardpoints of most fighters. Even the subsonic JASSM-XR is probably too big for many fighters. The F-15EX has a centerline hard point that can handle 7500lbs, which probably handles the large hypersonic missiles currently under development. Otherwise these missiles are going on bombers not fighters. The JASSM-XR may not be that heavy, but is almost certainly over 3500lbs. How close to 5000lbs I wouldn’t venture to guess. While the 30,000lb MOP bunker buster is not a fighter weapon, the 5000lb bunker busters are also pretty much an F-15 weapon.
The F-35 has two external hardpoints that can carry 5000lb weapons. That’s great, though of course that means you are flying in beast rather than stealth mode. The F-16? It doesn’t have any 5000lb rated hard points, they top out at 4500lbs. And the 4500lb hardpoints are usually used to carry external fuel tanks leaving the maximum weapons size at 3500lbs (on two other hardpoints). That could handle a JASSM-ER, but it is possible that the JASSM-XR may exceed the 3500lb limit. The F-16 also is very short range, about half the F-35 range, on internal fuel. So if you put heavy weapons on the two hardpoints that can handle heavy weapons you have a range issue. Yes there are conformal fuel tanks. There is also the centerline tank, but that is where you mount the Legion pod. So you can’t have IRST and lots of fuel and heavy weapons. The F-16 also has internal space limitations for many systems, so that you need to hang electronic warfare (and other) equipment that is carried internally on the F-15, F-18, and F-35 in pods. So what if you could design an aircraft that was in the same class as the F-16 (small, light, relatively inexpensive) but addressed these limitations? Perhaps that is what the revelation that a clean-sheet aircraft is being considered are all about.
Think of such a clean sheet aircraft as more internal fuel, more space to bring at least some podded systems inside, and a hardpoint or two that are always free for heavy weapons. At least meeting the 5000lb threshold, but imagine one that can handle 7500lbs. Now, beyond the anti-cruise missile mission, you have a 4th generation fighter that could handle the full gamut of standoff weapons. That’s interesting, though I’m not sure why you wouldn’t just buy more F-15EXs. Only details of what the aircraft is and what it costs will explain that.
The growth in standoff weapons is just one change, and perhaps the less interesting one, in terms of why more 4th generation (and by that I do mean 4+++ generation) fighters could make sense. The big investment area right now is in “loyal wingman” and other air-launched drones. These are often described as attritable, that is cheap enough to risk. Some may be attritable, some may be expendable, and others as undesirable to lose as the fighter itself. But as much as possible they are what you send into harms way. They have autonomous capability, but are under the command of a manned aircraft. They come in varieties for air defense vs strike vs other missions. They could be stealthy or not. They could be long range, or not. In any case, if your fighter is acting as the controller of such drones and it is the drones that are sent into harms way, why exactly do you need a stealthy fighter? It depends on the mission and specific scenarios, but it is not hard to imagine that as the Air Force re-examines the fleet mix in light of “loyal wingman” drones, ubiquitous long range standoff weapons, and other developments (e.g., efforts to create low cost cruise missiles), it finds a significant portion of its mission set doesn’t need a stealthy manned fighter. And that could put it on course to a roughly 50/50 mix of stealth vs. non-stealth fighter/attack aircraft supplemented by a large number of loyal wingman kinds of drones.
Now is this the right strategy? I don’t have a strong opinion yet. I certainly don’t see things as black and white. Not every fighter has to be a stealth fighter. But what is the right mix? That I don’t know.