The successful flight of XB-1, the world’s first independently developed supersonic jet, recently took place at the Mojave Air & Space Port in Mojave, California. XB-1 was flown by Boom Chief Test Pilot Bill “Doc” Shoemaker, and Test Pilot Tristan “Geppetto” Brandenburg flew the T-38 chase aircraft which monitored XB-1 in the air. The inaugural flight marks a major milestone toward the return of supersonic travel.
We talked to both pilots, Doc and Geppetto following XB-1’s flight to hear more about the milestone day, the lead-up to the first flight, and what’s ahead.
Bill “Doc” Shoemaker, Chief Test Pilot
What did the lead-up to first flight look and feel like?
For the years leading into a flight test program, your role as a test pilot is that of a skeptic. You should challenge the assumptions made by the team, and challenge the team to stretch its imagination when considering how the airplane might behave. As you get closer to the first flight, you have to make the transition from skeptic to believer. When you’re lined up on the runway for a first flight, you have to believe that all concerns have been adequately resolved, that the airplane and team are ready to go. You may have flown the simulator for hundreds of hours, but you really need to be ready in case the airplane doesn’t behave like the simulator.
What was the pilot mindset going into the day?
One thought that occurs to a pilot going into a first flight is: I don’t want this to fail because of me. You have an outsized impact on the outcome of the flight because you’re the one at the controls. You are confident that the team is well prepared, the plan is sound, and we have done everything we can to get ready. That’s the “intellectual” sense of readiness that you need to have. You also need to be ready to listen to the airplane and only ask of it what is required to get safely back on the ground. You also have to expect the airplane is going to show the team something we haven’t seen in the simulator. You only push the throttles forward when you’re confident the team is ready for whatever surprises the airplane might have in store.
Why was the landing gear down?
It’s very common to leave the gear extended during a first flight for a few reasons. If you have a malfunction after the gear is raised, you then have to worry about getting it back down. With XB-1, there are alternate ways to get the gear down if the primary method doesn’t work, but that takes time. Especially because you want to be slow and deliberate as you go through the steps in the alternate procedure. And in order to afford time for that in the air, it requires additional fuel. That means extra weight on takeoff and landing, which in turn means higher speeds. This did not align with our goals for the first flight and adds additional risk.
Why was XB-1 flying with a high angle of attack during the first flight?
The reason XB-1 flew at a high angle of attack is that an airplane needs to make lift with its wings equal to its weight in order to stay in level flight. The way that a wing makes lift is through angle of attack (the angle that the incoming air meets the wing). More angle of attack, generally means more lift. XB-1 and other supersonic aircraft tend to have relatively small wings in order to reduce their supersonic drag.
XB-1’s relatively low speed on first flight was intentional to investigate a small part of the flight envelope. For XB-1, we lifted off at about 10 degrees angle of attack and we flew the approach and touchdown at about 12 degrees angle of attack. Typical for a general aviation airplane would be maybe 4-5 degrees angle of attack, which is not too different from a commercial aircraft.
Do you have a fastest or favorite aircraft you’ve flown?
Of course XB-1 is high on the list. It’s a really unique airplane with fantastic performance. But I am partial to the F/A-18, which I flew for years in the Navy. You can fly it around an aircraft carrier, which is some of the most interesting, challenging, and demanding flying you can do.
Tristan “Geppetto” Brandenburg, Test Pilot
What are the goals of a first flight?
During a first flight, it’s the first time for a lot of things. And it’s an opportunity to learn from the aircraft in a way we’ve never learned before. The structures are flexing in a new way, the wings are generating lift for the first time, there’s faster airflow over the fuselage, fuel is transferring at a higher rate, and so much more. All the systems are working together during flight for the first time in the air, and we’re gathering data to assess performance. While all of that is happening, the biggest and most important goals of a first flight are to successfully and safely take off and land. As strange as it sounds, our goal for XB-1’s first flight was to make it as boring as possible.
What is the purpose of a chase plane?
The chase aircraft and pilot are there to play a supporting role during a test flight. The chase plane acts as the eyes and ears outside the primary aircraft — in this case, XB-1. I’m in a unique position where I can see things from 10 ft away from XB-1. For example, I may be able to see a leak before instrumentation can measure it. I can see the flight control surfaces moving. On XB-1’s next flight, the chase pilot will be able to monitor the retraction and extension of the landing gear for the first time. Additionally, the chase pilot takes as much workload as possible off of XB-1 and the test pilot. That means handling things like coordination with air traffic control and keeping track of where we are in the airspace. Finally, our airborne videographer, Matt Segler, is in the back seat of the T-38. Not only are the pictures and videos he captures really cool, they are also vital to data analysis.
What does it feel like to be part of a milestone like this?
First flights are a rare thing and it’s incredibly special to be a part of one. Mostly I feel gratitude toward the entire XB-1 team who made this happen. A lot of people worked for a long time to make this flight a reality and I’m just glad I got to be a part of it.
What’s next for XB-1?
Following XB-1’s flight, the team will systematically expand the flight envelope to confirm its performance and handling qualities through higher speeds. This includes in-flight checks of all systems, as well as multiple test points demonstrating safe margin to flutter (vibration) boundaries. We anticipate a total of 10-20 flights before we reach supersonic flight.
When XB-1 is ready for its first supersonic flight, Test Pilot Tristan “Geppetto” Brandenberg will be at the controls.
Do you have a fastest or favorite aircraft you’ve flown?
My first love is and always will be the Super Hornet. But in preparation for flying XB-1, I got to fly the F-104, which is by far the fastest aircraft I’ve ever flown. All that being said, I think the aircraft I’m most excited to fly is XB-1.
