What It’s Like To Fly The F-15EX According To A Boeing Test Pilot

webnexttech | What It’s Like To Fly The F-15EX According To A Boeing Test Pilot

While the F-15 may have been in service for nearly 50 years, much has changed during that time. One of the most impactful technical enhancements to the iconic fighter has been the major redesign of its flight control system. The Advanced F-15 now features digital fly-by-wire. This means pilots can maneuver the jet in an unrestricted manner in all regimes, without the fear of the aircraft departing from controlled flight. It has also unlocked a host of other benefits and features that work in part with other upgrades to transform the F-15 into a more potent weapon than ever before. The new control system was fully illustrated at the Dubai Air Show, held in the United Arab Emirates, in 2023, where Boeing performed an impressive flight demonstration of the Advanced F-15. The routine utilized an F-15QA of the Qatar Emiri Air Force and it was designed to highlight key performance features of this new breed of Eagle. The routine was flown by Jason “Mongoose” Dotter, an F-15 experimental test pilot, and Mike “Houdini” Quintini, an F-15 flight test weapon systems operator, both of whom are employed by the jet’s manufacturer Boeing. The War Zone talked in depth with Boeing F-15 Chief Pilot Matt “Phat” Giese, who helped plan and coordinate the demonstration. Our wide-ranging conversation not only explored what it’s like to fly the latest iteration of the legendary F-15, but also how its other features work in tandem to bring entirely new capabilities to the Eagle’s repertoire. The War Zone: In basic terms, can you tell us what the fly-by-wire system gives the latest F-15? Giese: The advanced fly-by-wire [FBW] flight control system allows the pilot to focus less on flying the airplane and more on executing the tactical mission. The design is such that the pilot can set the flightpath marker on the horizon and the jet flies straight. We have a digital rig on the jet, so it’s never going to change and it means the pilot and Weapons Systems Officer [WSO] can focus on displays, on the sensor management, and actually being tacticians and battlespace managers, as opposed to worrying about how the jet is flying. The digital rig of flight controls on fly-by-wire jets is much easier, faster, and more accurate as opposed to the legacy flight control system, where the actuators were rigged via adjusting the length of the mechanical input control rod ends to the actuator where resolution was limited to a half turn on the rod end. The digital rig extends to four decimal places in accuracy and should only need to be overhauled once in a jet’s lifetime assuming no major control surface changes or replacements. The other thing fly-by-wire gives is redundancy and reliability. In a six-year flight-test program out at Palmdale [California] on the advanced fly-by-wire flight controls, we attempted to spin this airplane and we were just unsuccessful even with lateral asymmetry [loading heavy stores on just one side of the jet]. So it is very rugged, it is departure-resistant even with large lateral asymmetries. We wanted to revisit the entire envelope during that testing that we hadn’t touched corners of in 20-30 years probably. So we had to go low and slow. We had to go high and fast, we had to go high and slow. We had to do all these things with the control surfaces that you would never regularly do in the airplane to try to force a departure or spin. And it’s just too good, it’s too redundant. It’s not going to depart from controlled flight. That’s great to know when you’re carrying 30,000 pounds of stuff and you have maybe a weapon that doesn’t come off. You don’t worry about the lateral symmetry. Again, that allows the pilot to focus on the mission at hand and completing mission tasks as opposed to being concerned about how the airplane is flying. The War Zone: In terms of engineering, what went into changing the F-15 from an analog control system with a stability augmentation system to the fly-by-wire system? Giese: A complete redesign in the 2011 timeframe extended into the 2013 initiation of flight testing. New identical flight control computers offer quad-redundancy on the stabilators and dual redundancy on the ailerons and rudders. The mechanical push-pull rods were removed and a control surface mixer was added to reconfigure flight controls in the event of failure or battle damage. We also incorporated a g-limiter and a roll limiter [which prevents a pilot from over-stressing the airframe by pulling excessive g-forces]. The War Zone: Can we talk about acceleration of the jet and high-end speed, and comparison between a clean and heavily-loaded F-15? Giese: The General Electric F110-GE-129 engines combined with the F-15’s unique air induction system with the movable inlet ramp allows us to get to those top-end speeds – just under Mach 2.5, actually Mach 2.497 – that has been advertised and that we demonstrated in the fly-by-wire flight control system development program. The acceleration to get to those high-end speeds is unmatched. Just as important as the high-end speed is low and slow fighting – high AoA capability is so important, and that’s what you can get from this platform as well. We do level accelerations on the first flight of this airplane [at the factory]. We climb up to 40,000 feet and can touch Mach 2 almost immediately. We see very good acceleration in both a clean jet or a jet that has conformal fuel tanks fitted. What’s probably equally as impressive is that you can take a clean jet and show those high-end speeds, and you can take a jet and put on 12 missiles on it for example and still get close to those high-end speeds. You can still fly all those maneuvers that you saw in Dubai last year with a loaded aircraft. To me, that’s an impressive show of capability because the clean demo is interesting to watch and it definitely shows fly-by-wire angle-of-attack capability and the power of the motors, but to demonstrate that with munitions on board is pretty darn cool. The War Zone: The F-15QA and the F-15EX feature large area displays (LAD) in both the front and rear cockpits. Can you explain why that was considered to be an important upgrade for the jet? Giese: Now that we’ve added these new sensors such as the APG-82 AESA radar, you’ve got the Advanced Display Core Processor II [ADCP II] mission computing processor that’s the fastest in the world. You add the advanced electronic warfare system EPAWSS with a lot of sensors and a lot of information and it’s important for the pilot and WSO to be able to manage that information in the cockpit. One way to do that was by adding a large area display. It’s a high resolution display and it’s touch screen. It’s also similar to the type of devices that pilots use nowadays to manage systems on an airplane. It allows the pilot and WSO to focus on very detailed pictures and large color displays and manage those advanced systems on the jet, and that provides a greater combat capability. Each cockpit can set up their own displays, their own colors, their own touch zones, how they want things to be displayed. All these young aviators going through pilot training right now, this is what they understand, this is what they’re used to. They’re going to fly the Boeing T-7 Red Hawk, and it has a LAD that looks very similar to this. They can then step into an F-15EX and they know exactly how to use it. It’s going to be very, very, easy to use. You can set up the LAD with an eight window display, a five window display, or two large displays. You can have radar, the targeting pod, or whatever you want on those larger displays, and it allows for more precise targeting. You can also see a lot of information about what the flight controls are doing, how they’re reacting and how they’re functioning. It’s a very redundant, reliable flight control system, quadruple redundancy on the stabilizers, dual redundancy on the other flight control surfaces. We’ve seen an Eagle fly home with a wing missing in the past and that was a customer with the old flight control system. I would say this one’s at least 10 times better! So just imagine the type of battle damage this airplane can take and still still RTB [return to base], with very good situational awareness on what is happening with the control surfaces. I can’t even remember my last ground abort for flight controls in the entire development of those flight controls over six years. I never ground aborted for flight controls, which while testing a new flight control system is just unbelievable. The War Zone: Is the LAD configured to present different displays in different situations? For example, does it automatically prioritize a particular display if something important relating to that display is happening? Giese: The large area display can be customized from one common layout for the fleet, down to an individual pilot’s choices. It will be up to the squadrons and pilot communities to take advantage of the customization options. We have looked at future fusion battlespace displays and have shown 3D looks in our simulators. Our mission systems engineers are pushing the apps and software forward for our fighters – this will become a reality for the future battlespace. The War Zone: Jets with the LAD have a new, narrower, head-up-display. Why did you change it from the wider HUD and what is the new HUD like from a pilot perspective? Giese: The new Low Profile HUD is very similar to an F-15C HUD. It was necessary to choose a narrower HUD in the advanced cockpit redesign due to incorporating the LAD – due to decreased physical space for the electronics required for the wide field-of-view legacy HUD. F-15C pilots will not see a distinguishable difference in the HUD in the F-15EX except for slightly crisper display symbology. The War Zone: Can you tell us about that flight demonstration in Dubai and what it was designed to achieve? Giese: The Dubai Air Show demonstration in 2023 was all about demonstrating combat capability. A lot of air shows have demonstration teams like the U.S. Air Force Thunderbirds or the U.S. Navy Blue Angels, and those demonstrations show teamwork and formation flying. With the Advanced F-15 we are all about demonstrating combat capability, that’s how we designed the demo – to be low and loud, and close to the crowd in order to get us maximum attention. We specifically designed our demonstration to stay in a very tight airshow display box to show how we can move, how we maneuver with high AoA [Angle-of-Attack] capability, and show the power of the two F110-GE-129 engines. These are the major components on today’s Advanced F-15. The War Zone: How do you go about developing a display routine like that? Does a lot of that work happen in the simulator? Giese: Hundreds of hours are flown in the Manned Flight Hardware Simulator [MFHS] to create and design an advanced demo like was flown in Dubai. Detailed and prescriptive Boeing processes and guidelines are followed that include formal documentation of training folders, sim practices, site surveys, emergency procedure practices, and multiple layers of oversight and instruction. Numerous flights are flown starting at high altitude and working down to airshow altitudes as confidence in the display builds. It’s a full-time job when done correctly to generate a safe and enjoyable demonstration of the aircraft’s capabilities. The War Zone: What’s your favorite part of that demo? Giese: I love all of it, the entire airshow from takeoff to landing, starting with the square loop to a tailslide at the end. But I would say my favorite maneuver is the demonstration of combat power, going from a slow speed pass down the show line at Cessna 172 speeds and going right into a double Immelman. I was the airshow coach and was in the control tower when we were demonstrating in Dubai. I heard from airshow coordinators behind me “wow, I’ve never seen that done before” and that was kind of what we were looking for. The War Zone: Bearing in mind the handling qualities you’ve outlined here, how does the F-15EX fare in basic fighter maneuvers [BFM] compared to an F-15E? The slow handling qualities and fly-by-wire in knowing it’s not going to depart the jet must make a big difference? Giese: Flying BFM in an F-15EX is more predictable, more precise, and allows pilots to fine-tune lift vector placement and the pipper [gun targeting symbology in the HUD] on the target. The EX is far better at BFM than the E-model, especially when considering the F110-GE-129 motor performance over legacy engines. The EX flies well at slow speed, it flies well when you’re fast, and it will not depart controlled flight. The War Zone: What sort of flight sciences laboratories do you have at Boeing to aid with the development of new F-15 systems and capabilities? Giese: We have some of the most advanced labs anywhere in the world. Everything the F-15EX does today was first tested in our labs and simulators. As we move into the digital future, and our fighters accept the apps-based solutions of the future – our labs and software teams only become more important to the capabilities of this jet. The War Zone: In terms of ongoing test work, what kind of missions are you currently flying out of St. Louis? Giese: A lot of the flying that you’ll see here are production acceptance flights after the jet has been built and prior to delivering the aircraft. The U.S. Air Force has F-15EXs down at Eglin Air Force Base in Florida and they’re very busy. They are mainly working on software upgrades and weapons development. They are also starting Auto GCAS [Ground Collision Avoidance System] technical discussions with Boeing. So they’re interested in those types of systems moving forward. I see a lot of advanced flight-tests, not just mission systems but in flight sciences on the F-15EX aircraft over the next several years. That might include roles that the WSO would have to have to play in the EX. The Advanced F-15 is currently a two cockpit airplane, and it is designed for a pilot and WSO. However, it is also designed so that it’s fully operable with a single pilot. Every sensor and mission system can be turned on and operated from the front cockpit, and that was an intentional move. But there are advanced missions on the F-15 today that a lot of communities are now realizing probably require another crew member in the rear cockpit, and that’s where the WSO is very, very, important. Some of those advanced missions could involve manned-unmanned teaming. Bringing in new technology improvements with communication and using the aircraft as nodes, things like that. The F-15EX is a perfect platform to exercise those capabilities and to test those capabilities as we move from manned machines to autonomous machines. In the future, there will be some sort of transition and this is a good platform to demonstrate some of that capability. As the F-15 has transitioned from air-to-air single role when it was initially designed through to the multi-role of the F-15E, now the F-15EX multi-role capabilities, the mission set just gets more and more complicated. It’s important to have another operator in the jet that can help manage a lot of those weapon systems and allow for more battlespace effects. Contact the editor: tyler@twz.com

0 0 votes
Article Rating
Notify of
Inline Feedbacks
View all comments