Sunday, April 28, 2019

The Ultimate Flight Sim - My Day as a B-2 Bomber Pilot

 Wikipedia Commons

Through a series of events and personal relationships that aren’t unique or interesting enough to detail here, it transpired that I found myself at Whiteman AFB one fine morning, waiting with almost childlike anticipation for my turn to get some seat time in a B-2 ‘Spirit’ Stealth Bomber simulators. This would be one of the very simulators used in the training of actual Air Force Spirit pilots in the exotic and esoteric operations endemic to the amazingly complex process of stealthily, accurately, and hopefully survivably task of delivering bombs, both conventional and nuclear, to their assigned destination. As you can imagine, this is not an activity commonly offered to civilians. In fact, I myself was quite surprised when I received the invitation; I had to read it half a dozen times to make sure it said what it actually said, not what I wanted it to say. Frankly, I still can’t fathom it. The only requirements, and they were very strict on this, was that we leave all personal electronics (phones, FitBits, etc.) behind. There were no non-disclosure requirements or TSA-style detectors, and if we asked a question that they couldn’t answer due to security concerns, they politely deflected them.

Despite my initial disbelief that a civilian would ever be allowed to do something like this, I found myself poised to experience what will surely be one of my top five most memorable days of my life. It will be added to a collection of notable days that include the sunny morning that I first flew the airplane that I had spent three years building, the out-of-the-blue chance to ride in a Huey helicopter, and the day I drove four different Porsches on the factory test track in Leipzig, Germany. Oh, and I are dare not omit the day I was wed and the ensuing birth of my daughter, although those actually fall into a different category. 

This, though…. this was something so unique and completely unexpected, and let’s just come right out and say it, so cool that a lot of people simply won’t believe it. For this they can be forgiven for the simple fact that I didn’t believe it either. You can buy a ride in a Huey, You can buy the Porsche test track experience. There is no price assigned to being invited onto an Air Force base to fly an exact replica of a front line, nuclear-capable stealth bomber because it cannot be purchased. As a measure of the value of this offer, consider that it was a nine hour drive and it rained every hour of that, both going and returning, and I would do it again tomorrow if the opportunity arose. 

Our group had a two hour window for the use of the sim, and as I was in the ‘friends’ column of the ‘family and friends’ chart, I was to ‘fly’ last. I was waiting in the sim control center and I was able to see the out-the-window view and the screens that make up the majority of the instrument panel as the family members took their turns, but was really interesting was talking about the technology with the civilian factory rep that is responsible for the upkeep of the simulators. The sim is lot like airline-level sims in that it is an entirely enclosed pod perched atop a collection of massive hydraulic pistons. 

There are five servers, each supporting a different aspect of airplane operation. Some run on a Linux platform, and at least one is hosted by Windows 10. The software is kept in sync with updates to the airplane systems and flight models; it’s a twenty year old airplane, so there have likely been quite a few changes. As changes propagate through the fleet one at a time, there are periods during which not all of the fleet are identical. When this happens, the individual simulators also diverge until the fleet is again homogeneous.

Awesome stuff for a guy that has been passionate about  PC-based flight simulators since the release of the T80-FS1 Flight Simulator from subLOGIC in 1980. It cost $25 in 1980 dollars, which is equivalent to $75 in contemporaneous dollars. That program eventually became the venerable Microsoft Flight Simulator, and I had every new version of that as well. 

The state of the art these days is almost immeasurable as compared to the early days - $75 will buy you an extremely accurate PC-based simulation of modern airplanes like the F-18 Hornet, the AV-8B Harrier II, or the Top Gun star, the awesome F-14 Tomcat. As I was looking at the B-2 sim's options for throwing system failures, just about any type of weather conditions imaginable, and all kinds of emergency situations, I didn't see very much that I can't configure in most of my PC-based sims. 

The best of the bunch is DCS World and, inconceivably*, it is a free download. It comes with a high-fidelity P-51, but you have to buy any additional planes and helicopters you want, all of which are worth every penny. They are predominantly military planes ranging from WWII fighters to modern jet fighters. There are also a handful of helicopters and one general aviation plane. New planes are routinely added. Hint: wait for sales - they happen a few times a year.

These can all be flown in Virtual Reality, which adds an entirely new level of immersion that you just don't get with a flat screen - the VR experience blocks your peripheral vision which allows your eyes to be the sole contributor to your sense of balance. If you really let yourself forget that you’re sitting in a stationary chair, it is quite easy for your eyes to convince you that you are feeling actual banking and pitching movements. It is equally capable of making you airsick. 

With 45 minutes left on the clock (way more than I had hoped for!!), it was my turn to head down to the drawbridge that leads to the cockpit. Normally the drawbridge is raised to allow the pod to move freely, but as civilians we weren’t allowed to use the full motion function for reasons not explicitly given. I personally suspect that it was to avoid a messy clean-up job should one or more of us got airsick. That turned out not to matter all that much anyway, for the reasons mentioned above. The B-2 is a big airplane, but its interior is almost entirely filled with massive fuel tanks, a large void where up to 80 500 lb bombs or a couple of really huge bombs can ride, and four jet engines. The pilots get a space the size of a Ford F-150 cab. There is a large center console supporting a host of boxes festooned with a plethora of knobs, switches and displays, not a single one of which was recognizable for its function. Not that I cared; I wasn’t there to learn the plane, I was there to fly the plane. I only mention the console because it sits in exactly the spot you would want to plant your feet as you crawl into the seat. 

Once I had awkwardly plopped myself into the Pilot’s seat (the one on the left where the person primarily responsible for the flying sits) and my friend had settled into the right side seat (far more gracefully),which is known as the Mission Commander’s seat (the boss of the whole endeavor), I took a few seconds to get a feel for the space. Keeping in mind that these pilots often fly missions lasting over 24 hours, you would think the seats would be well cushioned and as comfortable as possible. You would be, in a word, wrong. I was sitting on an ejection seat and the “cushion” was a tightly packed parachute. It wasn’t quite like sitting on stone, but it was close. Being of slight build and not well endowed with natural cushioning, I cringed at the thought of having to endure that seat for seemingly endless hours in the air. I didn’t spend any more than a few valuable seconds thinking about it as I was almost instantly overwhelmed by the broad spread of screens, instruments, and other indecipherable things spread out in front of me.

My own airplane is flown with a stick (as opposed to the steering wheel-ish yoke you would see in an airliner or a Cessna) so I was instantly comfortable with it. I fly mine with my left hand, though, because my throttle is a single knob emerging from the center of the panel, but the B-2 has the throttles on the left side, just like fighters to. The stick was comfortable in my right hand, and the set of four throttle controls fell naturally under my left hand. I was surprised at how small they were; all four fit comfortably into my hand. If you compare that with the relatively massive throttles of a passenger jet, you will understand the difference. The view out of the windshield (not sure if that’s what the Air Force calls it - it probably has a three letter acronym (TLA) like just about everything else military related) was expansive. I would estimate it as around a 200° arc. As I saw later in the actual airplane, that’s a little less than they have in the actual jet, but there’s not that much reason to look around that far anyway, at least in the sim. 

We were soon ready to go and the operator set us up for the flight operation that I had explicitly requested. My desired flight scenario differed from the more typical requests, which I suspect are more commonly focused on takeoffs and landings. During more than 1,000 logged flight hours, I have done more of those that I could ever count While they wouldn’t have lacked appeal, they came nowhere near what I wanted to try my hand at, something that a civilian is very unlikely to ever do: air-to-air refueling. I have always been fascinated by it, and assumed it to be one of the more difficult skills that the already highly capable pilots must learn. If there was time left after that, though, I did entertain the notion of trying a landing.

We started out about one mile behind the KC-135 tanker, level at 25,000’ altitude and 260 knots. The speed doesn’t really matter, though - it is all about the relative speed between the tanker and the receiver. Before starting the approach to the tanker, I wanted to get a feel for the flying qualities of the bomber. The feel of flying the bomber was what you would expect from an airplane whose mission was almost completely dependent on a very stable platform: ponderous. 

I was not the least bit surprised at the glacially slow response to control inputs, but I was shocked at the relatively high stick forces. My little airplane is flown with very, very little force or movement of the stick - it’s actually primarily controlled by light pressure on the stick rather than large motions. If you were to watch my hand during an entire flight, you would likely not see any movement larger than half an inch, and that would only be for a steepish turn at landing speed. In the B-2, it takes an estimated 10-15 pounds of force to move the stick. Full deflection of the stick to either side gives you a response of… almost nothing. That took a lot of getting used to after years of flying a plane that could do an entire roll in a second or two, if it was stressed for it. 

This was surprising, but not hard to understand. The very mission of the airplane is to be a stable platform. No one wants to spend 24 hours flying a plane that is in need of constant correction. It would be like 24 hours babysitting a precocious and hyperactive three year old. On the other hand, when you have become accustomed to instant response to your control inputs, it is a recipe for disaster to attempt an intricate refueling operation with controls with an endemic, anemic response. More on that soon. But rest assured: there is a TLA for it.

After getting a general idea of the control feel and response, I was ready to approach the tanker. The first step is to slowly approach the tanker from below and behind until you reach a position relative to the tanker called “pre-contact.” This would entail radio contact with the boom operator in the tanker, at which point the operator would drop the refueling boom down to our level. You are very close to the tanker at this point, and the goal is to very slowly begin to move closer to the end of the boom. 

Wikipedia Commons

By ‘slow’ they mean a relative velocity of about one foot per second. This is performed with very small, but very frequent, changes in the throttle positions of the four engine controls. At this point I fully understood why the throttle controls were sized as they were. The idea was to approach in a straight line and any level of asymmetric thrust on the collection of engines could induce some yaw, which would be very unwelcome indeed. Even with the small changes in thrust, there was a commensurate change in altitude. Plane goes faster, plane goes up. Unless, of course, you make quick corrections with the stick. But as we’ve seen, there are no quick responses to be had from the ultra-stable plane. Having made a control input without seeing a response, my autonomous reflex was to move the stick more. By that time, though, the plane had finally gotten around to responding to my first input, so I reacted by shoving the stick forward, resulting in the exact same over control, but in the opposite direction. This all very quickly adds up to a pilot-induced roller coaster simulator. This kind of thing naturally has a TLA - it’s known as PIO, or Pilot Induced Oscillations.

PIO in and of itself can lead to some spectacular failures. Combine it with a flying wing like the B-2, which just like every other wing wants nothing more than to climb, and you are begging for a problem. In my case, that problem ended up in an unwanted climb that went so far as to cause us to collide with the bottom of the tanker. The sim is very, very accurate in what it models, but fortunately it doesn’t model the mid-air explosion of two valuable military assets. It was also quite embarrassing. Best of all, though, we were only a reset button away from starting over and trying again. It was also only the first of two things that I did that would have broken the real airplane, but the other incident is yet to come.

My friend took over and flew us back to the pre-contact position and it was fascinating to see and feel. The left and right side throttles and control stick are tied together, so by lightly resting my hand on the controls I could feel his inputs. The astonishing thing about them was how rapid they were. Neither control stopped moving more than a second at a time. He could see and respond to changes in our movements relative to the tanker that I could not even hope to see. I like to think that the difference was due to the 30 year difference in age, but that’s just an excuse. The raw talent on display was awe inspiring. Again, that’s no surprise. B-2 pilots aren’t selected because they have just average innate abilities, after all. There are fewer B-2 pilots than there are astronauts. 

My second, third, and possibly fourth efforts weren’t as deadly, but I still failed to get into a position that would allow the refueling boom to reach the receptacle back behind the cockpit of the plane. It’s actually pretty far behind the pilot’s location, so at some point it completely disappears from view, unless you accidentally run into it, which I did at one point. You have to maintain the proper position by a combination of using the visual position of things on the tanker such as the perspective of a couple of antennas mounted on the belly of the tanker and two strips of lights, one of which helps you with fore and aft position, and the other which helps with altitude control. When you get to this point, the operation from our point of view became nothing more than flying very tight formation with a four-engine Boeing.

That’s not easy. One challenge is the aforementioned PIO, but with the added complexity of areas of turbulence generated by the tanker. Suffice it to say, twenty minutes or more of this kind of flying results in a pool of sweat, and in my case, a crease in the surface of the parachute from instinctive clenching of certain muscles. It took a few minutes to get a feel for the inputs I would need to maintain the relative position, but there wasn’t nearly enough to become adept at it. I managed to get the boom attached twice, which is actually very, very gratifying, but it turns about that you only have 6 (or was it 9?) feet to get slowed down to the precise speed of the tanker. Both times I got connected, I was only able to stay that way for a few seconds.

That was good enough for me, and by that point we only had a few more minutes to try a landing. Unfortunately, the heading of the tanker was away from the base and we had travelled over 200 miles while I was ham-fisting my way through an operation as delicate as brain surgery. My friend called the operator and had him give us a 200 knot tailwind, but it still wasn’t enough. Just to have something to do, he suggested we do some low altitude flight, his suggestion being 100’ above the ground. This is not the forte of a stealth bomber, though, and to be brutally honest, the graphics down that low were far worse than what I have at home on my PC-based sims. I had a better suggestion.

We were doing 500 knots, so there was plenty of energy to quickly climb up a few thousand feet. After asking for permission, I decided to try a barrel roll. If you aren’t familiar with the term, Wikipedia has this to say:

A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on both its longitudinal and lateral axes, causing it to follow a helical path, approximately maintaining its original direction. It is sometimes described as a "combination of a loop and a roll." The g-force is kept positive (but not constant) on the object throughout the maneuver, commonly between 2–3 g, and no less than 0.5 g. The barrel roll is commonly confused with an aileron roll.

Because Wiki referenced it, this is what they have to say about the aileron roll:

The aileron roll is commonly executed through the application of full aileron in one direction. In some lower powered general aviation and aerobatic training aircraft, prior to applying aileron input, the pilot must begin the maneuver by trading altitude for airspeed (i.e. diving). This helps achieve enough airspeed to complete the roll without losing rudder and aileron control. The minimum airspeed needed depends on the aircraft's design, but is generally about 120 to 200 knots. Because full aileron is applied, structural limitations prevent many aircraft from performing the maneuver at very high speeds.

With the roll rate of the B-2 being accurately described as “glacially slow,” and the very likely chance that it would simply fall out of the sky once inverted, I deemed the barrel roll as the safest choice. And in order to spare you the suspense, here’s what happened: I did it. We made it all the way around, albeit with substantial loss of altitude. At this point I had already experienced something only a handful of other people have ever done. I was satisfied well beyond even my most optimistic hopes. But there were still two minutes on the clock. What to do? Hmmmm.

A loop. I wanted to try a loop. My friend had never heard of anyone completing a loop in the sim, but I was gung-ho to try it. I suspect that it probably has never been tried by an actual pilot - I know that simulator training is treated as being every bit as serious as flying the actual airplane and I doubt that a pilot working towards the responsibility of delivering nuclear weapons cannot afford getting a reputation of being frivolous. Not the case for me - I had precisely nothing to lose.

Having already made a short story long, here’s a brief synopsis of how it went. 

I climbed us back up to 8,000’, put us in a shallow drive to get as much scoot as the bird would take, and pulled the stick about halfway to two-thirds back. I didn’t want to use full back stick in the beginning of the loop because I intuited that I was going to need a lot of altitude to survive the backside of the loop. We went across the top of the loop at a pretty slow speed, but it was enough to get the nose headed back down. I pulled the throttles to idle, but I didn’t think to deploy the speedbrakes.  We actually made it through the loop, but I am pretty sure that it would have over sped and over G’d the airframe. It definitely would have caused a brutal meeting with the Wing Commander. I will never know if the speedbrakes would have alleviated that or not, but it doesn’t matter: I made a loop in a full-fidelity simulation of a B-2 bomber.

If that wasn’t enough (and it sure as h*** was!!), doing that loop also conveyed upon me a minor and short-lived celebrity status with the squadron of B-2 pilots later in the day when they gathered for some drinks and comradery. If someone had told me about all of this back in the early 80’s when I was a lowly airman maintaining the side-looking reconnaissance radar on the infamous SR-71 Blackbird and was in awe of the astronaut-ish pilots, I would never have believed that some day I would be chatting with them as if we were peers.

I hope to never forget that day.

* It does mean what I think it means.

1 comment:

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