J-3 Cub Vs. F-15 Eagle”€”At 100 Feet

As the writer of a dozen or so stories on how to save fuel and continue to fly in an era of $5/$6 avgas, I've stressed over and over how you can nearly always reduce your fuel consumption (and, therefore, your operating cost) by 10% to 20% if you simply fly higher, where 55% to 60% power is all there is. That means operating at 9500 feet MSL or higher pretty much all the time.

Well, perhaps not all the time. I had my early introduction to flying in a remote section of America where we regularly flew quite a bit lower than that, and I loved every minute of it. When you're flying CAP search and rescue, high altitude is anathema to the mission.

Then, too, after I earned my license a few years later in California, I often traveled above the local terrain in a variety of minimum-performance airplanes that would have been challenged to even reach tall altitude.

My late friend, Don Johnson, based his prize-winning J-3 Cub at nearby Corona Airport, and he used to call me on a sunny Sunday morning and say, "Hey, Bill, d'you wanna go to lunch?"

If I had something else planned, I'd often cancel it, so I could flash back to the '40s and share Don's immaculate Cub. Don had lost his medical some years before, and he regarded me as his safety pilot, ironic since he had at least 1,000 hours in Cubs, and I had less than 100.

Besides, cruising a few hundred feet above the ground at 60 knots can be a soul-satisfying experience without the need for much practical application. Learning to read the wind on the ground by watching cows graze facing out of the breeze and looking for the lee in lakes and rivers was fun.

It was also interesting to travel no faster than traffic on the highways, waving through the Cub's open door at the cars below as the drivers waved back and immediately accelerated away from us just to see if we could keep up. We couldn't, but who cared.

Our flight plan was nearly always the same---start the engine, depart Corona and fly in whatever direction people weren't. Mostly, we chose to aviate away from the population. After we left the houses, the shopping centers and the roads behind, we'd drop back down to 300 to 500 feet with only the glory of 65 hp to protect us, bathing in the simplicity of flying in one of its simplest forms. Johnson's Cub was as playful as a Husky puppy, cavorting in the sky, willing to chase the imaginary ball wherever we chose to throw it.

Don and I were the same way, silly grin on our faces, long hair blowing in the breeze (remember, this was the '60s), temporarily relieved of any concern for gravity or departure stalls or spins or anything else that sometimes brings pilots to grief. We flew with the joy of uncomplicated sky overpowering our senses and the smell of roses and cows permeating our nostrils. (When will someone invent a smell-attenuating headset?)

My time in the Cub taught me that a J-3 almost never does anything wrong, and even when it does, it's in no hurry to do it. It was the best airplane I've ever flown for demonstrating adverse yaw---you led every maneuver with rudder, then followed up with stick. Do it any other way, and you'd be the brunt of jokes for anyone who witnessed your amateurish lack of coordination.

We did have a few close encounters with birds at that height, but other than that, the flying was gentle and unhurried. Don is no longer with us, and his estate sold his Cub for far less than it was worth. I wish I could have bought it.

At the opposite end of the low-level spectrum, the U.S. Air Force takes operating at minimum AGL to the high-speed extreme. I was fortunate to ride along on a minimum altitude demo flight several years ago in an F-15 Eagle. I flew with Lt. Col. Tim O'Keefe, then-commander of the 433^rd Weapons Squadron out of Nellis AFB in Nevada for a demonstration of what the Air Force calls "doctorate-level fighter pilot training."

Modern air-to-air combat relies more on heat-seeking missiles than cannons, so the WWII tactic to always attack from above doesn't necessarily apply today. In fact, a hot airplane against a cold sky presents a more attractive target for a missile looking for a heat signature. Some kills are even made beyond visual range, over the horizon where the two adversaries may never see each other, and a hot airplane against the hot ground makes a poor target.

For that reason, it may be better to be below your adversary in some air-to-air situations. To that end, the Air Force trains F-15 aviators to fly and maneuver as low as 100 feet at near-supersonic speeds.

I was invited along on a wild 1+30 ride in an F-15B to show me what a Mach II jet fighter could do in the hands of a skilled pilot. For a civilian with perhaps 30 hours in military fighters, the F-15 represented the tip of the spear, allegedly the world's most capable air-to-air fighter. (The F-22 has now assumed that mantle.)

Our takeoff weight at Nellis was 43,000 pounds, and the big, turbofan F100 engines were capable of developing 25,000 pounds of thrust apiece in max afterburner. In other words, our power-weight ratio was 1.16 pounds of thrust for every pound of airplane.

As every fighter pilot knows, lots of power is good, more is better and too much is just enough. With such a tidal wave of thrust under your left palm, the F-15 falls into the latter category. Release the brakes against max military thrust, and power comes on like a light switch. The F-15 comes out of the hole with an enthusiasm you might mistake for automotive, perhaps a Ferrari Berlinetta or Porsche Turbo. The airplane can leap into the air in less than 900 feet and bust the Mach in a vertical climb.

That would have been fun on my flight, but the sonic boom probably wouldn't have gone over too well with hotel owners in nearby Las Vegas. Instead, we settled for about 75 degrees of pitch and managed ground level to 39,000 feet in one minute, 50 seconds. You do the math.

(Back in 1975, a specially prepared F15, nicknamed "Streak Eagle," set 12 world time-to-climb records for 3,000 through 30,000 meters, flying out of Grand Forks AFB in North Dakota. The "Streak Eagle" required only 27.6 seconds from brake release to 3,000 meters, for a climb rate of 21,650 fpm. The high jump to 20,000 meters (65,000 feet) demanded a mere two minutes, three seconds for a climb at 31,500 fpm, faster than an Apollo Moon rocket. The 30,000-meter leap (97,500 feet) stopped the clock at three minutes, 28 seconds, for an average climb of 28,100 fpm.)

For this flight, our clearance was "ground level to 50,000 feet in Restricted Area Rxxxx." We probably weren't far from Area 51, but at that time, the top-secret base allegedly didn't exist, and there was no controversy over what went on in the skies northeast of Las Vegas.

Colonel O'Keefe let me test my G-tolerance to about plus 7.0 with some combat maneuvers at 35,000 feet, before we let the "Eagle" run out to Mach 1.5 (about 1000 knots, the limit with the centerline tank in place). Then, O'Keefe commanded a descent into a small valley, and he took control and leveled the jet at 300 feet AGL with the airspeed at 400 knots.

There was a fairly straight road that ran up the center of the valley with telephone poles spaced evenly along one side. O'Keefe lined up parallel to the poles, pushed the thrust levers into low burner, and we descended to 100 feet AGL and watched the knot count jump up to 500, roughly a mile every six seconds. At that speed, it's difficult to focus on anything closer than a half-mile on either side of the airplane. Fighter pilots call it the Star Wars effect, a condition where anything that isn't on the forward horizon or well to the sides becomes an incomprehensible blur. The telephone poles to our left, spaced 125 feet apart, looked like stakes in a picket fence flashing by at seven per second.

As we rocketed into a slightly wider section of the valley, O'Keefe pushed the power into full, fifth-stage afterburner and slammed the "Eagle" into a hard, 70-degree, banked left turn, still maintaining 100 feet above the desert at a blistering 500 knots. Everything below turned to an indistinct smudge of cactus, horned toads and sand.

The colonel had forewarned me not to be leaning forward during the hard 360 or the G's would pull my head down to my knees. He was right. Just to make the point, he repeated the maneuver, I straightened my neck the second time around and had an abbreviated view of slicing across the desert with the F-15 in a near-vertical bank.

The second maneuver O'Keefe showed me was a ridge crossing. Again, this was performed at extreme high speed and low level in a theoretical attempt to evade a pursuing enemy.

As we approached a predetermined point in the valley, O'Keefe again warned me to keep my back straight, then executed a hard-right vertical bank toward a slight V in the ridge line. As we shot through the cleft into the next canyon, O'Keefe continued the turn to inverted and pulled hard down the back side, trying to minimize time spent with the hot jet silhouetted against the cold sky. We rolled back to upright and dropped down to a guesstimated 100 feet altitude again, still screaming along at .70 Mach.

My brief exposure to the F-15 "Eagle," much of it at less than 300 feet and 500 knots, was certainly an adrenaline rush. Low-level flying can be its own reward, whether it's flying a leisurely J-3 Cub or taking an afterburner ride across the desert at close to the speed of sound.

As of January 1, 2016, Senior Editor Bill Cox has logged 15,100 flight hours in 321 types of aircraft. He also holds 28 world city-to-city speed records, has made 211 international delivery flights, and owns and flies a LoPresti Mooney. You can email Bill at flybillcox@aol.com.