The Pilot's Lounge #120: Cobra

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The Pilot's Lounge

Overhead, the massive, wide-chord blades begin rotating. Behind me the whine of the turbine builds as Walt Plentis goes through the start sequence and the 1800 horses of the Lycoming T53 collectively ask if we know what we're doing, if we really want to wake them up to power a two-place aircraft. Walt assures them that we are serious and introduces fuel. The igniters light it off and rpm and temperature needles move upward. The entire aircraft shakes and rocks on its skids. Those are big mother blades overhead; it takes some kind of power to get them whirling. As they spin up, seeming to grab hold and shake the helo to its foundation, I feel the torque in every fiber. It's warbird time.

It Started Innocently Enough ...

All photos  Frederic Lert

All photos Frederic Lert

Walt Plentis and the Cobra

The idea was a quiet lunch with Walt Pentis, restorer of helicopters, former corporate pilot and ex-Army aviator and mechanic. I'd been in the Pilot's Lounge at the virtual airport, chatting on the phone with Walt about his involvement with an AH-1S Cobra, when he suggested lunch at a place near the Oakland-Pontiac (Michigan) Airport. I wanted to find out more. I have been convinced that the Cobra was one of the coolest and toughest-looking helicopters in the sky, ever since I put together a model of one as a kid. No matter what my friends who served in Vietnam called it -- Cobra, HueyCobra or Snake -- as far as I was concerned, it set the standard for the whole attack-helicopter concept. It was capable of enough destruction to provide very-close air support to protect the guys on the ground and looked more than mean enough for any self-respecting combat pilot. Over lunch I found out that the Cobra I'd seen flying around is the tip of the iceberg, the first to be restored in the project he's become heavily involved with: adding a helicopter division, so to speak, to what had been an all-fixed-wing warbird restoration and sales outfit, Provenance Fighter Sales. Provenance's principal, Tony Raftis, has been in the warbird business for several years. With more and more of the Vietnam-era and later turbine helicopters finding their way into civilian hands, Tony and Walt got together and Walt's end of the business is now restoring and refurbishing Bell AH-1S Cobras and OH-6s. Provenance has started with a few that were released from various armed forces and that are in widely varying condition. The plan is to restore and refurbish them in the next few years for the civilian market. They are becoming increasingly popular on the warbird circuit and are starting to be used for airborne forest-fire fighting, primarily for the observers who help lead the fire bombers in and -- potentially -- to carry and drop fire retardant as well.

Huey Escort

Cobra Nose Guns

Over lunch I got more details and history about the Cobra. In Vietnam, the Army was using Bell UH-1 Huey helos for its concept of the air cavalry, to move ground forces rapidly to where they were needed. Unfortunately, the unarmed Hueys were getting shot up with some regularity and, harking back to fighters escorting bombers, the Army went looking for a pure gunship to escort the Hueys. Bell had experimented with the idea and was able to develop what became the Cobra in short order. Using the engine and transmission from the Huey (the transmission limited max power to 1400 hp), a tandem-cockpit helicopter was created for the purpose of carrying as much firepower as possible. It did so in the form of a minigun and cannon in a turret under the nose and missiles and rockets on stub wings. The original version, the AH-1G, entered service in 1967. It proved very successful in its escort and ground-support role, so much so that it was the subject of numerous modifications as production continued for decades. I learned that the Cobra that I had seen flying is painted in Israeli Army colors, because the person making the design decision thought it just happened to be the sharpest paint scheme he'd seen on a Cobra. While the Israelis use Cobras to this day (after great success taking out Soviet-built main battle tanks in combat in the 1980s), this particular one had only been owned by the U.S. Army before it was released to civilian life. Before Provenance came to own it, it spent some time in Hollywood, playing roles in the movies Home Fries, Courage Under Fire, Con Air and G.I. Jane, as well as a number of commercials. What I didn't expect as I tucked away the last bite of the enchilada was Walt casually asking, "Want to fly it?"

Did You Have To Ask?

Cobra Cockpit

I follow as Walt does the walk-around inspection, then I climb up the steps on the side. I slide in under the open canopy and into the front seat. Man oh man, is this thing shaking as the rotor comes up to speed. This Cobra was built as a trainer, so the front seat is for the instructor. (Normally it was the gunner's seat; the pilot flies it from the aft seat.) The stick -- oops, in a helo it's called the cyclic -- controlling pitch and roll is not in front of you; it's to your right, where it falls almost perfectly to hand. Full travel is less than a half-inch in any direction. It has been made clear to me that this cyclic only is hydraulically boosted, so the instructor can overpower the student in the back seat. Therefore, if Walt says, "Let go," he isn't going to be kidding. The visibility is superb in all directions. On the panel ahead, the engine instruments have come alive and indicate that all is healthy. Walt runs through the pre-takeoff checklist, explaining what he's doing as he goes. He started his Army career twisting wrenches on Cobras in the 82nd Airborne; later, after transferring to the National Guard, he went through flight training and flew Apache helicopters and, in an interesting twist of fate, Cobras. He is a helicopter CFI and happens to hold just about every rating a mortal can, including CFI for airplanes and gliders as well as being an A&P mechanic. He's been around Cobras long enough to know what they will and won't do. In combat, the Cobra had a gross weight of 10,000 pounds with fuel, two-person crew, the massive storage area below the crew full of ammunition for the cannon and minigun in the nose turret and the missiles and rockets out to the side. (An eyepiece arrangement on the pilot's helmet made the turret point where he was looking.) Demilitarized, empty weight is down to 6800 pounds. With 262 gallons of usable fuel (figure on burning 90-100 gph) and two people aboard, we're more than 1000 pounds under gross, so it's no wonder this machine seems ready to leap of the ground as the power comes up.

Hover Isn't Tough ... With Enough Power

Walt raises the aircraft into a hover. He explains that, in a helo, every control input has an effect on every other control. Those pedals underfoot are not rudder pedals; they are anti-torque pedals. The engine is spinning that big slab of a rotor; therefore, as Isaac Newton explained in his Third Law of Motion, there is an equal and opposite reaction, so the helicopter wants to spin in the opposite direction. The tail rotor exists to prevent the fuselage of the helo from playing corkscrew, and the anti-torque pedals control which way the tail rotor is going to push the aft end of the ship. Adding power means we go up, but it also means we start to rotate, so pedal input is needed to keep us pointed in the desired direction. The twist-grip throttle is on the collective, which I find by relaxing my left arm and letting it hang down to my side. Pulling up on the collective means going up, so long as there is sufficient power and rotor rpm. In a helo, more than in almost anything, there is no substitute for power. I was about to discover that I was in an aircraft that, for one of the few times in my flying life, I could not complain about having too little power. In the hover, I stay gently on the controls and become aware of the minute, almost indiscernible inputs Walt is making. The wind is anything but calm and is burbling around a big hangar off to the right, yet the Cobra is rock solid, three feet off the ground, staying right over the same spot. I sit and enjoy the way Walt anticipates the wind. It's not often a person gets to fly with someone who handles an aircraft at this level of mastery. "OK, now I'm going to have you handle one control at a time and work you into hovering this thing," comes through your headset. Darned defective headsets ... I could swear I just heard Walt say that I am going to hover. That could be ugly. The one time in my life I tried to hover a helicopter, the comment made to me from an onlooker was that it was like watching a monkey try to balance a basketball on the head of a pin.

Walt turns over the anti-torque pedals first. In moments I am silently grateful for the flying time I have in Luscombes, for it only takes only tiny pressures -- no discernable movement -- on the pedals to get an instant (and that's the only word for it -- instant) response. This is the way a warbird ought to be, an extension of the pilot's thoughts, perfectly responsive. So far, so good. Walt takes back the pedals and passes over the collective. Power is set, so I don't have to mess with the throttle; I just make tiny inputs up and down to hold altitude. At first it's a little difficult finding a suitable reference to tell how high we are and -- at one point -- I can't figure out why things are not moving around and Walt informs me that I've actually landed and the helo is simply sitting on the ground. Oops. And I thought I was holding altitude in the hover so well. Next I take the cyclic and the fun begins. On this control, there seems to be a tiny delay between cause and effect, perhaps due to the hydraulic boost. Even as I tell myself to make minuscule inputs -- nothing more than just gentle pressure -- it takes a while before I calm down the level of over-correcting to keep within an area the size of a baseball infield. Finally, I try all three controls, with Walt right there. I am mindful that you can easily overpower him, which would not be a good thing. The result provides some comic relief for the folks on the ground, but this is still far easier than the piston helicopter with its low-inertia blades I took a lesson in so long ago.

Up and Away

Walt suggests that we go see what the Cobra will do up and away from the airport. I agree. Departure clearance is received and suddenly it's as if someone loaded us into a high-speed elevator. In moments we are climbing sharply away at over 1500 fpm and accelerating, accompanied by the rhythmic thump of the blades letting us know that they are absorbing all that power behind us and putting it to work. In no time flat we are a couple of thousand feet up, torque is set at 85% (max is 88%) and we're cruising along at just over 135 KTAS. Flying along, the overwhelming sensations are of power and agility. Even at cruise speed, it becomes apparent that this helo can turn almost instantly, either by wrapping it around steeply or by pushing a pedal and pointing the nose where I want it. From what I can tell, this ship can fly along sideways, so it can hit a target almost no matter where it is. For some reason, I remember reading a piece by a British pilot who flew during World War I about how terrifying the Fokker Triplane was because a good pilot could cause it to point in almost any direction thanks to its amazingly responsive and effective controls. It, too, could fly along nearly sideways and put its nose on a target; a most disconcerting state of affairs for its enemy. As I experiment and delight in the responsiveness, I cannot help but think what a shock the Cobra must have been to the enemy when it first showed up on the battlefield.

High-Speed Acceleration

At Walt's suggestion, we return to the airport to see some of what the Cobra will do down low. I make an approach to hover over the runway numbers and then Walt takes it to show a few pedal turns and then demonstrates just how dramatically this snake will accelerate. In moments I am looking at the runway ahead through the top of the canopy as the helo is pitched steeply nose down, blade tips only a short distance above the runway, forcing air aft to propel us along. I feel as if I am being shot out of a gun. As the departure end of the runway approaches, Walt applies a little aft cyclic, the world falls away and we are suddenly at pattern altitude. Laughing, I wish there were time to do it again and again. As Walt hover-taxis to parking, I can't help but think what a ball it would be to put on an airshow with three or four Cobras. With their phenomenal maneuverability and ability to change speed so quickly, they would be right in front of the crowd all of the time. There would be no dead air because they don't have to go into the next county to turn around, as it is with some jet performers. The pyrotechnics that have come to characterize contemporary warbird shows would be extremely impressive with Cobras, down low, showing how they protected ground troops. At warbird prices, a Cobra is for those who can put it to work in the fire-fighting world or the serious warbird set. No matter who operates a Cobra, it will definitely turn heads on the ramp. You can reach Walt Plentis via email to find out more. Now I've got to start putting nickels, dimes and quarters in that great big jar in the closet ... See you next month.

Want to read more from Rick Durden? Check out the rest of his columns.