I can remember around 1972, when I first began getting involved with the Lightweight Fighter program, that it was difficult to visualize just what they had in mind when I was reading about the cockpit layout for the F-16. When I tried to picture what it would feel like on someone’s wing during a night weather approach to about two hundred and one-half, I was not too sure I would like what I visualized. However, within my first ten seconds in the cockpit, I couldn’t believe we didn’t do this 100 years ago. It’s great!
I did realize that there would have to be changes in the way I approached some flying aspects that I’d been using in the F-100, F-104, F-4, and others. First of all, the increased seat-back angle made for a far more comfortable cockpit. It was difficult to gracefully enter. But once in the seat, it felt super. The rudder pedals only moved one-half inch, so I could put them where they felt comfortable. In airplanes, like the F-4, I was always concerned with being able to get full rudder pedal throw (and a lot of it), so I was forced to fly with the pedals practically under my chin. I was not forced to reach for the stick in the F-16. Instead, it fell nicely to hand just over the arm- and wristrest.
As the YF-16 progressed more and more toward an operational configuration, numerous small changes appeared in the stick and armrest/wristrest geometry. The first stick did not move at all, but rather depended strictly on the amount of force you were using to determine the desired pitch or roll rate. It was possible to fly the airplane very well with this fixed stick, but it was decided it would be still better if a small amount of motion was added. The stick still moves only three-sixteenths of an inch aft, three-thirty seconds left and right, and next to nothing forward. Although this is a very small amount, it is sufficient to give you the tactile cue of making an input. It also lets you know when you’re up against the limiter – something that was difficult to do with the old fixed stick.
Why essentially no movement forward? We found that, under negative g, you tend to move up and forward in the seat enough to increase the amount of forward stick more than you want to. As a result, it was decided to provide for minimal forward stick movement. The small amount of movement in the other axis seems to be just about the right amount. This stick movement was another area where people not completely familiar with the aircraft made a lot of erroneous inputs about how much movement was really needed. Stop and think about it. If you have much more movement in the puff direction, you quickly reach the point that you’re pushing on the bottom of the stick while pulling on the top. That assumes you have your arm on the rest and are not trying to fly the airplane by moving your whole arm. Instead, you should be using only hand or wrist movement. So, like the mistakes people made in evaluating the F-16 from an aerodynamic standpoint, people were making bogus decisions because they had not taken the time to completely understand the F-16.
Once I started flying the F- 16, I noticed right away that I had a whole new set of muscles in the front of my neck and upper chest. In thinking about this a little further, it should be obvious that the difference in the seat-back angle requires you to exert some physical effort to keep your head from being forced backward under elevated g loads. Even though you’re leaning back in the seat, the natural human tendency is to carry the head still aligned with the local vertical. This is much like watching television at home in your easy chair. Unless you’re asleep, your head is not back against the headrest. The airplanes you’ve previously flown wanted to force your head forward under the same g level. This slight discomfort with the newfound muscles quickly passes, just like any other new physical endeavor.
One often-heard item concerning this new seat-back angle is that some people feel they can’t look toward six o’clock as easily as with their previous airplanes. Once again, pay some attention to the fact that this is a different airplane. With a conventional cockpit, you’re sitting erect or leaning slightly forward in the seat. The human makeup is such that the head rotates fairly well about the vertical axis. Therefore, it’s fairly easy to rotate the head and eyes far enough left or right to see over your shoulder. You get comfortable with such a motion because you’re familiar with it. These very same people who are complaining seem to forget that they’re usually doing nothing but looking at aircraft structure once they get cranked around. Looking at six o’clock in the F-16 requires a little different technique. Instead of simply turning your head, try this (don’t even think about leaning forward): use the “towel racks” to push or puff yourself left or right as far as you can go. (Both directions will work, and, with a little practice, you’ll quickly learn which direction is better at that particular moment.) Now, lean your head toward your shoulder in the same direction you’re leaning your body. With a little practice, you can get to where you can support your head with your shoulder while you’re pulling g. Now rotate your head about the now-leaning vertical axis and you’ll be able to look nearly right down the back of the airplane. And better yet, those clever devils have not put any aircraft structure in your way. The only possible interference now is from the top of the seat. Amazing.
I’ve not heard many pilot complaints about the lack of a canopy bow in the F- 16. I get the impression that everyone is impressed with the markedly improved visibility that results. That is certainly the most lasting impression I had on the initial takeoff I made in the airplane. For a minute, I thought I’d forgotten something. I finally realized that I could see like in no other Air Force airplane I’d ever flown.
However, I have heard some complaints about reflections in the canopy at night. You must remember that the original design of the F-16 revolved around the role of lightweight daytime air-to-air fighter. However, this quickly changed to one of multirole fighter. The possibility of the aircraft spending much more time in the arena where it might encounter birds was one change. Without fully understanding the physics involved or the tradeoffs required, a lot of attention was suddenly focused on the F-16’s birdstrike problem. As a result, the canopy thickness went from three-eighths inch on the prototypes, to one-half inch on the full-scale development airplanes, and finally to three-quarters inch on the production version. Therefore, the possibility of reflections ricocheting around inside the transparency (and then into your eyes) increased markedly. It’s also interesting to note that this additional canopy thickness cost you twenty-two pounds of additional weight per one-eighth inch increase.
While I have mentioned birdstrikes, let me digress for a minute on that subject. It’s important to realize what we’re talking about when the subject comes up for discussion.
First of all, the failure mode with a birdstrike in the F-16 is rarely one of penetration (that is, the bird does not usually come through the canopy). Instead, the impact puts a big depression in the canopy. This depression (dent, if you prefer) then progresses back along the canopy in a traveling wave, giving rise to the possibility that it (the wave) will rap you on top of the head hard enough to incapacitate you. The sweet spot required for this to happen is hardly six inches by six inches, roughly centered on the head-up display, or HUD. Anything outside this area does not create enough of a dent to hit you as this traveling wave passes by your head. I feel the odds against just such a hit are astronomical, but it was not my decision to make. So, what you now have is a canopy that will take a four-pound bird in this area at something in excess of 350 knots. This capability assumes that you are sitting at design eye. If it looks like the mission is going to require that you fly at high speeds in an area where you know there are a lot of birds, you should make note that you can get an increased safety margin simply by lowering your seat below design eye. It is also very interesting to note that the F-16 is one of only a few airplanes that has been so thoroughly scrutinized in this area.
There are several other airplanes (I won’t mention any here, but you would recognize them instantly if I did) where the failure mode is one of penetration. And the airspeed that this penetration occurs is not too high (more like around 250 knots). What happens with these airplanes is that the bird hits anywhere on the windshield and travels up the windscreen, making a dent similar to one on the F-16. The difference is that, once it gets to the canopy bow, this traveling wave is severely snubbed by the canopy frame. The result is an immediate failure of the transparency, and your single-place aircraft has suddenly become occupied by another warm (but rapidly cooling) body. This is not too conducive to a much longer sortie on your part. Of course, there is always the remote possibility of taking a condor right in the chops at 600 knots in any tactical airplane, in which case all bets are off.
Anyway, we were talking about reflections. Because of several reasons beyond the control of both test and operational pilots, we have to live with a canopy whose thickness is conducive to reflections. Also the canopy geometry, which gives us such excellent visibility in the daytime, is hard to light from the inside without some annoying reflections. We have to recognize they exist and learn to live with them. There are a couple of things you should consider. First of all, learn to fly with the lights as dim as possible. Although not yet designated as the primary flight instrument within TAC (as it is with the Navy F-18 community), perhaps the time has come to consider using the HUD to fly with at night (or in the daytime for that matter). Through some judicious use of the night filter (in conjunction with the day, night, and/or auto bright switch in concert with the brightness knob), you can get the HUD where you can see it perfectly without any annoying reflections. With the panel and console lights very dim (to almost off, which the HUD will allow), you can virtually eliminate any annoying reflections. In fact, that’s exactly what we’ve been doing lately – eliminating reflections.
After spending a lot of time and money in apparent dead ends (electroluminescent strip lighting, many different filters, different bezel lights on the various gauges, and so on), we came up with the following solution: We added a master switch for the interior lights in much the same manner as the external lights. We use the present rheostats to set up the various panel lights to where we can see everything comfortably. Then, with a hands-on switch, we turn everything off (the warning lights are rigged to stay dim) and fly using the HUD until we need to check something. Then it’s click on, do our check, and click off. It works great.
There is still the problem of having to contend with the radar electro-optic, or REO, display, but we are working on a filter to help here (and it looks like we’ve come up with one that works well). With some practice on your part, you can come up with the right combination of brightness, symbology, and contrast settings that will allow you to use the REO at night and still not flood the cockpit with green light. There will still be those areas, such as night weather approaches (either single-ship or on the wing), where it could be a bother. In such cases, you can turn it down enough (even off) to where it shouldn’t interfere. Experiment a little and you’ll see it’s not too hard to come up with some personal settings that will allow you to see outside through the small amount of reflections that remain.
One final area before we leave the canopy is the refraction and internal reflections of such things as runway lights. I have seen these and do not like them either. I wish I could remove them entirely, but I can’t (with the present thickness). But don’t despair. I have never seen a circumstance in which it was not obvious which lights were the real ones and which ones were the pretenders. If you realize that the phenomenon exists, you have no reason to bite on the wrong picture.
I mentioned using the HUD. It seems like there’s a lot of misunderstanding about what it is that you now have in front of you. It is everything you had heads down, except now it’s all in one place. And better yet, you can still look at the real world while you’re looking at instruments.
This article appeared in the Semper Viper special issue of Code One Magazine.
Joe Bill Dryden died on 24 May 1993 when his F-16 crashed during a company acceptance flight over north central Texas. He will be missed by many people.