Spokane-based Rocket Engineering Corp. and JetPROP LLC arent well-known locally, but the two affiliated aircraft-modification companies are establishing a strong presence in the general-aviation industry nationally.


Specializing in the installation of more powerful engines in popular, mass-produced single-engine planes used for business and pleasure, the affiliated companies have grown gradually but steadily here as their reputation among aircraft owners has spread.


Together, Rocket Engineering and JetPROP now employ nearly 50 people at the Felts Field building they share, and that number is increasing by about one employee per month. Darwin Conrad and Jeanie Sadler, who are majority owners of both companies, say the companies work force could more than double in size over the next five years if demand for their airplane conversions continues to climb.


Conrad, who is president and CEO of Rocket Engineering and managing member of JetPROP, says JetPROP likely will expand by the end of this year into a new hangar thats to be built just east of the 12,000-square-foot building, at 6427 E. Rutter. Plans also call for that building to be expanded next year to include additional office and production space.


Were getting busier and busier as time goes on, he says.


Currently, Rocket Engineering and JetPROP are certified by the Federal Aviation Administration only to do specific piston-engine conversions on four-seat Mooney M20J and M20K models and jetprop conversions on six-seat, pressurized Piper Malibu and Mirage models, respectively. Conrad says, however, that the companies long-term success will hinge on their ability to come up with other aircraft-modification projects that have strong market potential, since each project has a limited market life span.


For competitive reasons, he declines to say anything about what some of those projects might be or when they might be rolled out. Were working on a lot of things all of the time, he says, grinning at his evasiveness.


For now, the companies are staying busy doing the Mooney and Piper conversions.


Rocket Engineerings conversion for the Mooney M20J is called the 300 Missile and costs about $68,000. It includes replacing the standard 200-horsepower Lycoming engine with a 300-horsepower Continental engine and swapping out the factory two-blade propeller for a three-blade model.


The companys conversion for the turbocharged Mooney M20K is called the 305 Rocket and costs about $78,000. It includes replacing the standard 210-horsepower Continental engine with a 305-horsepower model and also installing a new oversized supercharger.


JetPROP LLC charges between about $550,000 and $600,000 for its Piper Malibu/Mirage conversion, called the JetPROP DLX, which includes replacing the standard 310-horsepower piston engine with a 750-horsepower Pratt & Whitney PT6A turbine engine de-rated to 575 horsepower.


All of the conversions are much more than simple engine replacements. They require removing basically everything from the cockpits firewall forward and installing new beefed-up engine mounts, as well as new exhaust systems, hoses, batteries, controls, wiring, instruments, and so on. Much of the cockpit also has to be removed to allow for installation of new systems and instruments. Rocket Engineering designed the modifications and manufactures most of the specialized parts needed to do the conversions.


From start to finish, installing a JetPROP DLX package on a Piper Malibu or Mirage takes about 15 weeks to complete, compared with six weeks for installing a 300 Missile or 305 Rocket package on a Mooney.


The conversions result in markedly better performanceshorter-distance takeoffs, faster climb rates, and higher cruising speedsand have received glowing reviews from customers and the nations general-aviation press.


While not inexpensive, Rocket Engineering and JetPROP claim their conversions can turn used Mooneys and Pipers into speed machines that outperform brand new versions of the same planes, at a fraction of the cost of buying the new aircraft.


Conrad and Sadler, both Spokane natives, started Rocket Engineering in 1990. That company spent several years researching and then obtaining Federal Aviation Administration certification to do the Mooney conversions and since then has done nearly 200 of them, Conrad says. The positive marketplace recognition generated by that continuing work provided a springboard for the creation of sister company JetPROP in 1996 and its certification by the FAA about a year ago to do the Piper Malibu/Mirage conversions.


Weve completed 16 jetprops and are doing one a month. Our goal is to get up to four a month, he adds.


The dramatic engine change on the Piper adds 17 inches to the nose of the plane, which gives it a lean-and-mean look, reinforced by a new four-blade, reversible propeller, with the air scoop directly beneath the prop, and large swept exhaust stacks that extend out from each side of the stretched engine cowling.


The payoff, claims Conrad, is not only improved performance, but also a safer, smoother-riding plane.


A jet engine is much more reliable than a piston engine, about 50 times safer because its basic design makes it much less prone to wear and breakdowns than a reciprocating engine, he says. Also, compared with some underpowered piston aircraft engines that are forced to work at or beyond their intended limits, the jet engine typically is operating at a level well below its rated capability.


On the performance side, the benefits are obvious. A JetPROP DLX can take off in less than half the distance of a standard piston-powered Malibu1,200 feet vs. 2,550 feetand climb at up to 3,000 feet per minute, which is more than double the standard Malibus 1,220 feet per minute, the Spokane company claims. The JetPROP DLX boasts a cruise speed that ranges from about 45 to 65 knots faster than the standard Malibu and has a 2,000-foot-higher maximum cruising altitude, of 27,000 feet.


For pilots who dont already own a Malibu, good used ones can be bought for $300,000 to $600,000, Conrad says, which means someone would be out about $850,000 to $1.1 million to buy such a plane and have the JetPROP conversion installed.


Because of the cost of the conversions, Conrad and Sadler say they expected most of their customers to be owners of older Malibus and Mirages. However, they have begun to receive some newer planes for conversion too. They say some of their customers are coming from as far away as Europe.


Given the costs involved, 300 Rocket and 305 Missile customers tend to be small-business owners and JetPROP customers tend to be owners of mid-sized to large companies with multiple business locations and hundreds of employees, Conrad says.


Conrad seems ideally suited to be heading up Rocket Engineering and JetPROP LLC. He is a former corporate pilot and current engineering-related flight test pilot for the FAA. He learned to fly when he was 17 years old and now has more than 7,000 hours of flying time in about 30 different aircraft. He says he began developing a love for flying at age 2 or 3 from his father, an electrical contractor here, who flew a lot.


Conrad also has an aptitude and extensive background in engineering. He says he went from winning science project awards at an early age to studying mechanical engineering at Brigham Young University and aerospace technical engineering at Arizona State University. Along with spending a number of years as a corporate pilot, he later worked at a couple of aircraft-modification companies, including Turbo Plus in Seattle and Machen Inc. here before he and Sadler started Rocket Engineering. He says he has participated in 21 successful supplemental-type certificates, which are the exhaustive FAA review procedures through which proposed aircraft modifications must pass.


He now oversees research-and-development and production activities at Rocket Engineering and JetPROP, and Sadler oversees personnel and parts.


Speaking generally about the business strategies he and Sadler have developed for Rocket Engineering and JetPROP LLC, Conrad says, We look for things the manufacturer could have done to make a better airplane, then research the feasibility and market demand for doing those after-market upgrades.


Its something we enjoy, he says. Its fun, and its neat to put out a good product that people get excited about.


Adds Sadler, It makes it all worthwhile.