New Power to the Commander

Will a bigger engine finally make this comfy, good-flying airplane fast enough?

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Super Commander

We were headed back toward Austin's Class Charlie airspace from our demo flight out to the west in a Commander 115, though it wasn't just any Commander 115. At the time it was the only one like it in the world. The frequency was pretty quiet. We were at 5,500 feet, about 25 miles out when one of the Austin Approach controllers gave us a call, "N115CE, say type of aircraft." "N115CE is a Commander 115."

"Uh, roger, is that a single-engine or a twin-engine aircraft?"

Then I got it. "Austin, N115CE is a single-engine Commander, but it's got a big engine, a Lycoming IO-580 in it. It's a new STC. This is the first one out there."

"Well, that sounds pretty cool," he came back on, completely forgetting about the AIM terminology for the moment, as I was. "I was wondering," he explained, "because you were doing 180 knots in level flight just a bit ago." (The controller, of course, was seeing our ground speed on his radar display. Our actual true airspeed was closer to 175, but he knew there was almost no wind, meaning that we were going fast. In his words, "cool.")

It's not very often that an STC can transform a nearly 40-year-old design into an airplane that's competitive with the latest new models, but that's exactly what the Super Commander conversion, which earned FAA approval late last year, looks capable of doing.

The promise of the upgrade is impressive. Replacing the existing Lycoming IO-540 in the 114/115 with the IO-580 adds at least 60 horsepower to the equation (though in fact, possibly much more) and gives the airplane the kind of cruise speed and climb performance that Commander owners have dreamt of for years.

A Complicated History

One of the more curious high-performance singles in the past four decades, the in-and-out-of-production Commander has been in many ways one of the most promising, too. There's a lot to love about the airplane. It's roomy, it's got nice flying manners and many of the models came from the factory well equipped and with fine interiors.

But the biggest downside is a tough one to overcome: It's always been too slow, and it gained that reputation long before the advent of Cirrus and Columbia singles, airplanes that both get a lot more performance from a similar sized airframe without retractable gear. Various normally aspirated models of the Commander 114 and 115 listed book cruise figures as high as 160 knots true, but those figures have always seemed really optimistic, especially on the earlier airplanes. Rockwell launched the first Commander single in the late '60s when it announced the development of the Commander 112 (along with a fixed-gear version, the little produced Commander 111). Powered by a 200 hp Lycoming four-cylinder engine, the 112 gave its owners a big cabin, which came in handy given the airplane's leisurely cruise and climb speeds.

The design got a much needed power boost in 1976 when Rockwell introduced the model 114, powered by a 260 hp six-cylinder Lycoming IO-540. Rockwell stopped building the airplanes in 1979, after having built around 1,000 in all.

In 1988 a new company, Commander Aircraft Company, bought the program and set up shop in Oklahoma, where it earned approval in 1992 for the improved 114B and, later, the turbocharged 114TC, incorporating a multitude of improvements. Later, it updated the models even more under the same type certificate as the 115 and 115TC. Neither airplane enjoyed much market success, and the company went bankrupt a few years ago after building around 200 airplanes. Its assets were acquired by yet another company, Commander Premier Aircraft Corporation (CPAC), which was formed by a group of more than 50 Commander owners, who were interested, for obvious reasons, in keeping replacement parts available. Since then CPAC has relocated to Cape Girardeau, Missouri, and is initially selling parts for existing Commanders, though it intends to relaunch production of the 115 later this year.

An Engine in Search of an Airplane, and Vice Versa

The Super Commander conversion is the brainchild of Jim Richards, who founded Aerodyme Corporation, a Burlington, Vermont, maintenance and repair facility, back in 2001. Richards' personal airplane at the time was a 1977 Commander 114, and owning it made him think the two exact things that countless other Commander owners have thought: One, "Isn't this a nice airplane," and two, "Wouldn't it be nice if it were faster?"

The search for a way to do that became Richards' goal, and as chance would have it, that quest dovetailed perfectly with Lycoming's desire to find a home for its big-bore six-cylinder engine, the IO-580.

Now the IO-580 started life ignominiously, as the chosen engine for Cessna's new 206 Stationair piston single. Only there were problems. The engine was late, which held up Cessna's launch, and once it did get engines, Cessna found problems with the cylinders. To avoid what it feared would be further development delays, it decided to scuttle the IO-580 selection, instead opting for the tried-and-true IO-540, which still powers the 206 today.

More than five years down the road, the IO-580, its issues apparently all ironed out, is installed in just a handful of aerobatic airplanes. Richards saw real possibilities with the 580, which delivers 320 horsepower, because the engine is very close in size to the IO-540. And Lycoming was an ideal partner, in part because it was looking for a home for the engine, which had languished since the loss of the Stationair program and in part because, according to Richards, it still believes strongly in the product.

The theory behind the additional horsepower isn't very complicated. It's a normally aspirated engine, so as you climb the power output decreases. At face value, it's a more powerful engine to begin with, and Richards, along with others, believes that Commanders never got full-rated power to begin with due to exhaust and prop inefficiencies. So even though the power output of the 580 decreases as it climbs, as is the case with all naturally aspirated engines, it still has a lot more in the bank at any given altitude than the IO-540 it replaces.

A Program Is Born

With help from Lycoming, Richards put together a plan for the conversion, and within a year he'd installed a 580 in a 1978 Rockwell 114. The airplane made its first flight in late 2005, and about a year later Aerodyme earned an FAA supplemental type certificate for it.

In addition to the engine swap, customers get a new prop, a 78-inch Hartzell three-blade Scimitar prop, and a new, lower cowl section. Airplanes built by Commander also get a new exhaust system, which is, strangely, an old-style Rockwell two-tailpipe system that fits the IO-580 to a tee and which, according to Richards, creates much less backpressure in the system, letting the 580 produce nearly full-rated power. The air filter is located right behind the round inlet on the lower cowl, and heated alternate air helps keep the filter free of ice when the conditions are right for it.

The conversion isn't inexpensive. With the new engine (around $57,000), prop (approximately $10,000), cowl and exhaust, plus the STC and the installation kit, the total cost is around $92,000. That cost can be brought down, Richards points out, by selling the old engine and prop on the used market, which can reduce the overall cost by between $10,000 for run-out components to as much as $30,000 for newer ones. As with many engine programs, the costs are most palatable for those owners who are looking at a complete overhaul in the first place.

Flying Fast in a Commander

Richards kindly stopped by in Austin to go flying with me as he was heading out to California to deliver the second STCed airplane, a 1999 Commander 115. It was late in the afternoon, and the wind was light and the air was smooth as we launched from AUS to give the most powerful Commander a try. In most installations, the Commander driver won't see any big changes when he straps in, as most of the changes are from the firewall forward. When you do start to fly, the changes are quickly apparent. Far and away the biggest improvement is in the airplane's rate of climb. While the book best angle of climb in the 115 is around 80 knots, Richards says that it's closer to 75 indicated in the Super Commander, which gives, he admits, much too steep a deck angle for most pilots' comfort. At a less startling 90-knot climb, we were seeing sustained initial rates well in excess of 1,500 fpm while burning about 25 gph, a typical figure for a big bore engine like this.

And even as we ascended, our rate of climb continued to impress. On our climb from 6,500 to 8,500 feet, we were seeing between 1,000 fpm and 850 at 110 knots indicated, which is just the kind of climb performance that operators of non-turbocharged Commanders are used to wishing they had. Most pilots want to know one big number when they ask about performance, and that's speed. How fast will it go? In the case of this, as with all airplanes, the answer is, it depends on how much fuel you put through the engine and how far you want to be able to fly.

The good news for the Super Commander is that it's fast or miserly, depending on how you want to set the power. At 6,500 feet (a density altitude that day of around 7,000 feet) we were getting 173 knots true at 25 inches of manifold pressure and 2700 rpm while burning right around 20 gallons per hour at 50 degrees rich of peak. At 8,500 feet at this same best-power setting, we were just a couple of knots off that mark, at 171 indicated.

But when we pulled the power back a bit, using 22 inches and 2700 rpm, we were still getting 165 knots true at just 16 gph. We didn't climb up that high, but Richards says that at 12,500 he consistently gets just better than 160 knots at just less than 15 gph. With 88 gallons in the tank at startup, there's a lot of range in the Super Commander at those figures.

And the installation seems to run very cool, too. Over the course of our hour-and-a-half flight, I never saw the CHT on any one probe go over 400 degrees. The airplane is equipped with cowl flaps, which helps get additional cooling air into the system when you need it. The cool performance is due in part to Aerodyme's own ram air induction system, which delivers a lot of additional air to the engine compartment, as well as to the dual oil coolers, which are a part of the installation package.

Aerodyme currently has six orders for its Super Commander conversion, and with nearly 1,000 candidate airplanes out there, Richards can expect to see a steady business for the foreseeable future. And he has other projects in mind for the Commander already, including a possible turbonormalized version of the IO-580 installation, as well as an STC to install the IO-540 in the normally 200 hp Commander 112.

For more information about the Super Commander conversion, visit Aerodyme's website, Aerodyme.com, or call 802/264-6400.