Plane & Pilot
Tuesday, March 6, 2012

Carbon Dating

Beautiful, refined, muscled like a linebacker: a Cub for the hotrod soul

"It's What's Up Front That Counts"
That ancient cigarette commercial slogan befits the addictive thrill of the SS's well-muscled pedigree. Although its LSA-on-superfood power persona has garnered excitement from customers and grumbling from competitors, when operated within company-specified parameters, it's indeed ASTM legal.

The CC340 is, at heart, a CubCrafters-reworked Lycoming O-360 mill that went on a diet—it's now less than 250 pounds—yet rams out 180 horsepower. The airplane is placarded for (and derives its TBO of 2,400 hours from) no more than five minutes at full power. Then it must be throttled back to 80 hp for boating around at continuous power settings.

The controversy?

There's a horsepower-specific formula within the ASTM spec that I won't bore us all with. It's meant to make it impossible for an LSA to have a big-horsepower engine and still end up with a useful load of more than two gnat's whiskers.

CubCrafters worked around that with the proviso, specified in the operating instructions, that the herd of 180 stallions only can run at full speed for five minutes. Then 100 of them have to graze and let the remaining 80 carry the freight. That way, the formula, calculated using the 80 hp rating, not 180 hp, does indeed work out to allow a workable useful load.

In the company's promotional literature, it's spelled out in red ink: "It is the pilots responsibility to operate the aircraft in accordance with the pilot operating handbook and aircraft placarding. There is NO governor or limiting system that controls the engines (sic) power settings."

The Cub Is A Small Bear
There are a few timeworn rules about taildragger flying, chief of which is you fly a tailwheel airplane from engine start to engine shutdown. Disrespect that rule, and that cute yellow bear will straightaway become an angry grizzly.

Corollary to that sentiment is advice from friend and UK aviation superscribe Dave Unwin, who suggests that before you even get in an airplane of the rear-wheeled persuasion, you note which way the wind is moving and visualize its potential effect on the airframe's aerodynamics.

Tailwheel airplanes require a singular skill—using your feet—that was rendered moot last century by Clyde Cessna, William T. Piper and all designers of nosewheel airplanes.

We're talking about adept application of the rudder, which aligns the fuselage about the yaw axis. Rudder skills are imperative for successfully flying a taildragger, since the concentration of mass (pilot/passenger) is behind instead of in front of the center of gravity of the aircraft. Once in motion, that center of mass (you) has inertia and wants to keep moving, and move it will, in our case sideways, right around the center of gravity and on to scraping a wing, mangling a prop and damaging your personal equilibrium in one tidy handful of seconds.

Taildraggers weathervane into the wind, and in motion will always try to swap ends if you don't stay on top of them with constant, small applications of rudder to keep the tail aligned with direction of travel. That's the big secret: Keep that fuselage straight with your tootsies (and appropriate applications of aileron in crosswinds), and you've got it.

Let that tail swing too far, though, at below-flying speeds, and it will quickly reach the point of no return, overruling all your frantic, but way too late, attempts to keep it in line. Pass that point and next stop: Groundloop Town, where you, the pilot, become hapless passenger and nothing more.

Call it The Grizzly Effect.

Many pilots are intimidated by taildraggers though they need not be. It's simply a flying skill, and, to repeat: The flying begins between your ears before you ever climb aboard. Many CFIs wish their students started training in taildraggers.

Once you're off the ground, taildraggers fly just like nosewheelers. Until that moment, you're always in the bear's lair. And that's a vulnerable place if you never learn to be fleet of foot.

Labels: LSAsPilot Reports

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