Tuesday, June 1, 2004
An Enthusiastic Cherokee
Maybe it isn’t the fastest 140 in the world…but then again it might be
Although the company hasn’t directly measured the power improvement on the Cherokee, a similar mod on a Skyhawk (that uses the same engine) was tested on a dynamometer and scored 23 additional horsepower. That’s a 15% power increase.
A little boost in climb and cruise goes a long way. Think three to five knots better cruise from the exhaust system alone. That may not seem like much, but it’s a significant performance margin for an airplane in the 115-knot cruise range. Specifically, I saw a 50-rpm power increase at the same density altitude, worth a four-knot speed improvement to 119 knots. This followed a 20% improvement in climb performance. All this was with the Power Flow system alone. Rhoads’ Cherokee is one of some 250 PA-28s flying with Power Flow’s tuned exhaust systems installed, and it’s a safe bet that most realize the same benefits.
But wait. Power Flow and Laminar Flow of Daytona Beach, Fla., are sister companies dedicated to the premise that speed isn’t only for Mooneys and Bonanzas. The two companies have specialized in extracting uncommon performance from unlikely candidates, and Rhoads’ Cherokee is the poster airplane for their efforts in the PA28 line. I flew the Cherokee again at the annual Sun ‘n Fun show, this time, fitted with the gamut of Laminar Flow mods, and the performance improvement was even more dramatic. The Laminar Flow mods included flap and aileron gap seals, flap hinge fairings, main-gear speed pants, a nose fairing and fuel tank fairings.
Collectively, all the mods, including the Power Flow system, cost about $8,000 plus installation. That might seem a sizeable investment, especially in an airplane typically worth less than $35,000, but consider what it buys you.
Rhoads’ airplane turned in a max cruise effort of 127 knots, a solid 12 knots quicker than its original speed and eight knots ahead of the pure Power Flow mod. Perhaps equally important, more so if you live out West where the rocks meet the sky, climb improves by probably 200 fpm over the stock airplane, a combination of more power and less drag. In fairness, Rhoads reports that he’s done some additional tweaking and squeezed another three or four knots out of the airplane since our tests, but we haven’t seen it, so we’ll take his word for it.
Like most Cherokee 140s, Rhoads’ airplane wasn’t designed as a weight-lifter, and all the mods probably add a little to the empty weight. The result is that, sitting on the ramp, empty of fuel and people, N140HC weighs in at 1,353 pounds. That leaves a 797-pound useful load or 509 pounds of payload after filling the tanks.
Piper does offer a hedge if you need to carry more weight inside the cabin. Full fuel is 48 gallons, but if you stop at the bottom of the filler necks, you’ll be hauling only 36 gallons. That will save you 72 pounds that can be allocated to the cabin, boosting payload to 581 pounds, a more realistic 2+2 allowance.
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Labels: Piston Singles