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Third Generation Twin Comanche PDF Print E-mail
Written by Bill Cox   

 

Mounting two engines on a Comanche was obviously a great idea. Mounting a pair of Lycoming IO-320s was somewhere between amazing and brilliant.” So says Twin Comanche owner Mike Adkins, of Butler, Tennessee.

It’s perhaps understandable that an owner of the type would be enthusiastic about his airplane, but Adkins expresses the sentiments of hundreds of pilots who’ve been fortunate to fly a variety of multi-engine machines, including the PA-30 Twin Comanche.

A reformed Wall Street analyst, as well as a pilot and instructor for nearly 50 years, Adkins knows whereof he speaks. He’s made a living in conjunction with flying machines long enough to have a deep understanding of all things aviation. He owned a glider school 30 years ago in New Hampshire, not far from the famous Mt. Washington where, says Adkins, “The winds and updrafts were sometimes so strong, you could cut loose from the tow plane at 1,000 feet and soar all the way to 30,000 feet.” Adkins has also instructed in turbine helicopters and jets, teaching in Cessna Citation jets.

Along the way, he’s owned a succession of airplanes, including a Cessna 120, Waco UPF7, a Cessna 310 and probably a number of others he’s forgotten. Today he flies a bush-modified Cessna 170 (with a 180-hp engine) and a Twin Comanche. “I prob­ably enjoy teaching tail wheel transitions more than anything,” comments the instructor.

Adkins and his wife, Patti (a U.S. Air 737 captain), always dreamed of refurbishing a Twin Comanche and went shopping for a 1964 turbo model two years ago—“I specifically liked the window line on the older Twin Comanches.” They found the perfect airplane. “It was a high time, slightly damaged machine with low-time engines, but otherwise a pretty reasonable example, and that’s exactly what we were looking for—a good, basic airframe prime for a full, ground-up rebuild,” Adkins comments. “Another attractive feature was it was already fitted with long-range tanks. We often like to fly long distances and the big tanks make that easy.”

Adkins’ enthusiasm for the PA-30 is mirrored by at least two generations of pilots. The first Twin Comanches were priced to make them competitive, not only with other twins, but with the top-line singles of the time. Beechcraft’s vaunted V-tail Bonanzas sold for about $34,000 in those days, and the first Twin Comanches were priced at $41,000—only 20 percent more.

Today the analogy continues. A typical 1964 model S35 Bonanza demands $77,000 and a ’64 Twin Comanche comes in at about $90,000— perhaps, more than coincidentally, 20 percent more. In other words, for only about $13,000 more, you can buy a roomier, more comfortable, better performing airplane that may be able to fly home after an engine failure.

If the price of admission is similar, that’s not to suggest operating costs will be the same. Adding the second engine does considerably more than double the operating expense. Twins typically fly with more complicated systems than singles—fuel burn obviously increases dramatically and other expenses also jump disproportionately. In one twin owner’s words, “Yeah, right. Operating expense does go up by a factor of two. It squares.”

As former 310 owners, the Adkins weren’t intimidated by the cost of operation. In collaboration with Mike Rohrer of Altus Aircraft in Altus, Oklahoma, an acknowledged expert on Twin Comanches, and interior specialist Mike Oakes of Buchanan Aviation in Concord, California, Mike and Patti invested much of their spare time and a significant amount of money upgrading the airplane. They mount­ed a new panel up front, including an S-TEC 55 autopilot with altitude preselect, plus a talented Garmin 530 nav system, dual ADIs, dual altimeters and other goodies.

The Adkins family also installed speed brakes, vortex generators and transformed the airplane from just another Twin Comanche to a multi-talented, long range, prize-winner.

“I like to fly high whenever possible,” says Mike, “and with the turbos in this airplane, I typically cruise at 14,500 to 17,500 feet, just below the flight levels. At max cruise up high and with a set of GAMIjectors installed, I can run the engines lean of peak, and I’ll burn probably 10 to 11 gph per engine.

“Flying three-and-a-half miles up is high enough to realize significant benefit from the turbos,” Adkins continues, “but not so tall as to loft up into the pressurized and turbine traffic. Technically, the service ceiling is listed at 30,000 feet, but another factor that limits the Turbo Twin Comanche to 20,000 feet or less is that the Lycoming IO-320s were never fitted with pressurized mags, and ignition begins to break down. Most of the time, I see 180-185 knots true airspeed at those medium heights, but I’m usually well above the weather and most other traffic, plus I’m always operating at least 2,000-3,000 feet above the terrain.”

The downside of the 162-gallon, long-range tanks is obviously reduced payload, and Adkins admits there’s not much allowance left after filling those monster tanks. “I can carry full fuel and about 350-400 pounds of people and baggage,” he explains, “but that works out just fine, as most of the time it’s just my wife and me traveling. The good news is, with all that fuel, the airplane has an easy seven hours endurance at high cruise, well over 10 hours pulled back to economy cruise. That provides us with plenty of options if weather goes down or plans change. Such endurance means we can cover 1,500 nm between fuel stops if we have to.”

I caught up with the Adkins duo at Oshkosh AirVenture. Flying their totally renovated Turbo Twin Comanche was like old times for me. Back in the 1980s, I was keeper of the keys of a most excellent PA-30 owned by auto racing photographer Jeff Hutchinson. Jeff’s job kept him on the road for eight months a year, chasing Formula One teams and drivers around the world, and he left his airplane in my care in Southern California for several years. Tough job, but someone had to take the airplane for walks. During those days and since, I’ve accumulated perhaps 400 hours in the type, and I share the Adkins’ enthusiasm for the PA-30.

The Twin Comanche makes an excellent choice for a traveling machine, despite (or perhaps because of) what came later. In the late ‘70s, everyone jumped on the light/light twin bandwagon, and there were suddenly a half-dozen different models available. In addition to the Apache, Twin Comanche and Beech Travel Air, Piper offered the T-tailed Seminole (basically a twin-engine Arrow), Beech adapted the Sierra to the Duchess and Grumman-American premiered the all-new Cougar. Many pilots who’ve been fortunate to fly all those models (this one included) regard the Twin Comanche as the best of the lot.

Today, the new kid on the ramp is the Diamond Twin Star, the first new multi in 30 years. The Twin Star is as modern as tomorrow and powered by a pair of 135-hp Thielert Turbo Die­sels. While the Twin Comanche was equally revolutionary in its own way back in the early ‘60s, it didn’t initiate the rush to multi-engine training. That job fell to the bulbous Apache. Piper’s slick little PA-30 nevertheless has the distinction of having trained more twin pilots than any other type. Even today, Twin Comanches continue to serve as multi-engine teaching machines around the world.

And therein lies the occasional rub. Such a constant diet of training initially resulted in an artificially high accident rate—not because of any basic design flaw, but a simple matter of exposure. In those days, the FAA demanded that Vmc (velocity minimum control speed) demonstrations be flown at low altitude, where asymmetric engine power was still high enough to cause the beginnings of a Vmc roll. (As twins with normally-aspirated engines climb higher, Vmc drops below stall speed, making it difficult to demonstrate single-engine control loss.)

Low level Vmc demos contributed to a number of accidents and triggered Piper to redesign later Twin Comanches with counter-rotating props, stall strips and a rudder/aileron interconnect that kept the ball in the center during all but the most violent maneuvers. This helped insure the airplane against spins. In hopes of distancing the improved airplane from the old, Piper even assigned a new model designation, PA-39, effective on all Twin Comanches produced after 1969. Today, the VGs (vortex generators) fitted to Adkins’ airplane further reduce the risk of a Vmc spin.

In a sense, turbocharging only exacerbated the Vmc problem, because it was possible to produce full-rated power all the way to 18,000 feet or higher. In another respect, however, the RayJay’s control system design made a Vmc roll less likely. The RayJay turbo was totally manual and utilized a second throttle to control boost. If you lost an engine with boost dialed in, you merely had to retard the two turbo throttles, and the airplane responded exactly like a normally-aspirated machine.

The obvious benefit of turbos in a twin (in addition to flying faster in the lower flight levels) is that single-engine service ceiling rises well above 10,000 feet. That means you can lose an engine over probably 80 percent of the North American Continent and still fly home, at least if the surviving engine doesn’t overheat and you’re proficient enough to handle single-engine operations in the first place.

Mike and Patti Adkins make optimum use of the airplane’s turbos on practically every flight. “With the turbos, I can maintain an easy 1,000-1,200 fpm for the first 15,000 feet,” Mike Adkins explains. “So there’s no reason not to fly high on any trip over 100 nm. We’ve become used to breathing oxygen on a regular basis and, it’s not an inconvenience for us, although it is an extra expense—about $5 per person per hour.”

For the Adkins family, the Turbo Twin Comanche offers the best of most possible worlds. It’s a comfortable traveling machine, modestly fast with twin-engine redundancy and operating costs aren’t nearly as high as for a Seneca, Baron or 310. “If you’re traveling cross country,” says Mike Adkins, “it’s hard to imagine a more cost-effective twin than the Turbo Twin Comanche.”

Mounting two engines on a Comanche was obviously a great idea. Mounting a pair of Lycoming IO-320s was somewhere between amazing and brilliant.” So says Twin Comanche owner Mike Adkins, of Butler, Tennessee.