Skunk Works

Other Voices

Alan Brown

I was Ben’s program manager. Building the stealth fighter, we had to tightrope walk between extreme care and Swiss-watch perfection to match the low radar observability claims of our original computerized shape. We didn’t have the time, money, or personnel to build a flying Mercedes. But we couldn’t allow even the tiniest imperfection in the fit of the landing gear door, for example, that could triple the airplane’s radar cross section if it wasn’t precisely flush with the body. So we took extra steps to hold in those doors and put on an extra coating of radar-absorbing materials.

We were well aware that what we were doing was outside the scope of normal engineering experience. We were dealing with radar cross sections lower by thousands not hundreds of orders of magnitude.

Many of the airplane’s details required breakthrough engineering, particularly in the engine intakes and engine exhaust system. The exhaust especially gave us fits. It was complex, using baffles and quartz tiles to resist telltale heat signatures. To keep us as stealthy as possible, we used only infrared systems to get us to the target and aim our bombs. These systems emitted no electromagnetic signals but were vulnerable in stormy weather because water absorbs infrared energy. We gave up 20 percent in aerodynamic performance because of the flat plate design, which meant we would have to refuel in flight more often to get to our target and back. The F-117’s range was twelve hundred miles.

I had anticipated propulsion problems, which we didn’t have, but two of our biggest problems were how to keep the tailpipe from cracking and the data measurement systems from icing. The tailpipe set us back months. The problem was that a flat tailpipe, which we had to use, was not structurally sound under high pressure and easily cracked. We just couldn’t find a solution and finally got General Electric’s engine division to deal with it; they were expert in high temperatures and we adopted their design. The air data measurement system, called pitot probes, could have sunk the entire project if we couldn’t perfect it. Doing so took us the entire two and a half years. These probes, which extended out the nose in stiletto shapes, recorded for the onboard computer static pressure, dynamic pressure, airspeed, angle of attack, and angle of sideslip so that the computer could make its microsecond flight adjustments. If those pitot probes iced up, the airplane would go out of control in two seconds flat. So ours had to be foolproof and, while jutting out from the airplane’s nose, stealthy as well. How to heat these probes to keep them from icing without having them become conductive and act like antennas to radar or infrared devices was a problem that ate us alive. We finally developed a nonconductive heating wire the thickness of a human hair.

Another big problem was canopy glass. The pilot must be able to see out with no radar energy seeing in. The pilot’s head would be hundreds of times larger on radar than his airplane. We had to develop coating materials that would pass out one without allowing in the other.

Occasionally we ran up against a problem that just didn’t make any sense. For example, suddenly a special ferrite paint we used to coat the fighter’s leading edges lost its radar-absorbing potency. We couldn’t figure out what went wrong until one of our people decided to confer with DuPont, our supplier, and discovered that they had changed the way they made the paint without informing us.

Ben kept a close eye on all our problems, but he was never a second-guesser. The most striking thing about his leadership—especially in comparison to Kelly Johnson, who was totally hands-on with technical people—was that Ben let us do our jobs with a minimum of interference. His style wasn’t to redesign our design of our engine the way that Kelly absolutely would have done, but to let us do our thing and smooth our way with the Air Force and Lockheed management. Yet the F-117A tactical fighter was every inch Ben Rich’s airplane. If he hadn’t pushed for it right from the outset, we would never have got into the stealth competition. He was the perfect manager—he was there for tough calls and emergencies. He would defend and protect us if we screwed up and keep us viable by getting new projects and more money from the Congress, convincing them and senior government officials about the value of stealth. He had a hunch and a vision—and it paid off handsomely.