Above & Beyond: Milk Run

How a milk run from an aircraft carrier nearly killed me

(David Clark)
Air & Space Magazine | Subscribe

(Continued from page 1)

“Stand by, Knightrider,” he said. “Supply wants you to move a load of milk back to home plate for dispersal. How many gallons can we load, max?”
With our fuel load, we could lift about 7,000 pounds, but I hadn’t a clue as to how many gallons of milk that would be. I looked over at Dave, my copilot. “Any idea what milk weighs?”
Dave shrugged and turned his palms upward in what is known in Navy parlance as an ensign’s salute.

“I need a number, Knightrider,” the air boss growled.

Forklifts began driving off the elevators with pallets of milk. I pulled the calculator out of my helmet bag and typed 7000. Now I just needed to know what to divide it by.

“Knightrider! I need a number—now.”
“Milk must weigh about the same as fuel, right Dave?”
Dave gave me another ensign’s salute.

I knew that jet fuel weighed about 6.5 pounds per gallon. Even though the voice in my head told me to slow down and think this through, I decided that a liquid was a liquid. I plugged 6.5 into my calculator. Just as the Boss started to growl again, I transmitted, “One zero five zero gallons, Boss,” with far more confidence than I actually had. It was meager comfort that I had figured in a 27-gallon cushion, just in case milk was a little heavier than fuel. How much heavier could it be?
“Okay, Knightrider. Here it comes. Be ready to lift as soon as we stuff you.”
In minutes the cabin was crammed with hundreds of plastic jugs that I prayed weighed no more than my hasty calculation.

“Knightrider, cleared for takeoff.”
I pulled the aircraft into a hover and stabilized it for a ground-effect power check.

Ground effect—the cushion of air that provides extra lift for a helicopter operating within one rotor diameter of the surface—can be a blessing or a curse. With a long hovering run, a pilot can accelerate in the ground effect cushion until reaching flying speed, thereby lifting far more than would be possible from a standard climbing transition. The carrier, however, presented the opposite situation. From our position adjacent to the deck edge, I would take off into a ground-effect hover, then transition over the edge of the flight deck, 90 feet above the water, to an immediate loss of ground effect. The voice in my head warned me as I raised the collective to increase rotor pitch and add engine torque, but the big voice in my headset drowned it out: “I need my deck, Knightrider!”
Normally I would have taken my time to evaluate a takeoff this critical. But this was the air boss’ deck, and he wanted it back. “Get that damn helo off my deck, now!”
Without the stabilized torque reading that would tell whether the aircraft would fly at this weight, and against my better judgment, I eased the cyclic stick forward and the aircraft lumbered across the deck edge.

Immediately we were in trouble. The aircraft settled, and I instinctively countered by raising the collective. But instead of slowing its descent, the helicopter settled faster. The steady hum of the rotors changed to a distinct whump whump whump, and the familiar blur of the rotors slowed until I could see each individual blade. A quick glance at the instruments confirmed that both engines were operating normally. I was simply demanding more power than they could produce, and the strain was making the rotor speed decay.

I should have predicted what would happen next. With a jolt, both generators kicked off and we lost everything electrical. Powered by the rotor system, the generators had been designed to “shed,” or drop offline, at 88 percent of optimum rotor speed to preserve torque for lift. The jolt was the loss of the flight control stability system. The helicopter was still controllable, but controlling it took far more work without the stability system. Things were starting to go very badly.

As the rotor speed continued to decay, I realized the only chance we had was to get back into ground effect. If I continued wallowing, the helicopter would “run out of turns”—lose lifting rotor speed—and crash, or settle into the ocean and sink. I had to try what the old salts called “scooping it out.”
Faced with an undesirable sink rate, it is counterintuitive to decrease either power or pitch, but scooping it out required both. To dive back into ground effect, I lowered the nose, and the windscreen filled with the sight of blue water and white foam. To preserve rapidly deteriorating rotor speed, I lowered the collective. The bottom dropped out and the ocean rushed upward. I blurted “Brace for impact!” Dave immediately understood what I was attempting and began calling altitude and rotor speed.

Comment on this Story

comments powered by Disqus