A Couple of KR's
Fixed Gears Are Now
The Choice of KR Builders
BY JACK COX
PHOTOS BY PHIL HIGH
Some homebuilt designs just seem to go on forever, and the KR-2 is one of them. We saw the tiny two-seater for the first time at Oshkosh in 1974...two of them, actually: Ken Rand's prototype, N4KR, and Wicks Organ's (now Wicks Aircraft Supply) N100MW, which had been built in just 74 days. Both were featured in the March 1975 issue of Sport Aviation, and here we are, 20 years later, writing about two brand new KR-2's that appeared at Sun 'n Fun '95. Hundreds, maybe thousands by now, have been built in the interim. It's hard to come up with a number, Jeanette Rand says, because so many sets of plans have been shipped to builders in other countries and she never hears from them again. We see pictures of completed KR's in magazines from all over the world, so we know they're being built and flown wherever wood, foam, glass and resin can be shipped, and that's nearly everywhere.
Twenty years ago builders started with a set of plans, a bag of bolts and a few metal parts and fittings, several boards of spruce, pillows of foam, 30 yards of Dynel cloth and seven gallons of resin...all of which cost less than a thousand dollars! Even after a VW engine, prop, control cables, instruments, avionics and paint were purchased, it was still possible for one to get into the air for as little as $2,500 to $3,000...and blow the doors off factory builts costing five to fifty times as much. That was the primary appeal of the KR-2: it offered about the greatest bang for the buck that was available at the time.
Little has changed in 20 years. The KR-2 can still be built in its original form, and although inflation has increased the prices of parts and materials, one can still be put in the air today about as inexpensively as anything available. Certainly for anything as fast. The difference today is that those who have a little more to spend have a lot more options. Premolded parts, a choice of several landing gears and much more are available, allowing the builder to tailor a KR to his or her desires and budget. Actually, there have never been two KR-2's that were built alike. The model airplane-like wood, foam and glass primary structure is so easy to build and the secondary structure is so adaptable to change that each builder seems to inevitably slide into doing his or her own thing on the canopy, the shape of the vertical tail or something. That's another thing builders like about the design.
The major change in the KR-2's we see being built today is in the landing gear. The original manually actuated retractable gear has largely given way to either a fixed taildragger gear, with both aluminum and composite springs available, or a tricycle gear. We'll be discussing one of each here.
TROY PETTEWAY'S TAILDRAGGER KR
Troy Petteway of Columbia, TN is the company pilot for Tennessee Aluminum Processors and is usually found in the left seat of the firm’s King Air 200. Otherwise, you’ll likely see him zipping around in his little Revmaster powered KR-2. Troy, who was born in Murfreesboro, TN and grew up in Dalton, GA, began building models when he was 10 and eventually progressed to RC models, which he still enjoys building and flying. His grandfather, Garland Pack, was a pilot in World War II and became widely known in the late 1940s and ‘50s as the designer/builder/pilot of five different midget racers (now Formula One), the most famous of which were #46 "Johnny Reb", #47 "Lit’ Rebel" and #2 "Grey Ghost." Pack later became a prominent figure in soaring and was operating a soaring school in middle Tennessee when Troy was growing up. It was Troy’s good fortune to solo one of his grandfather’s TG-3 gliders when he was 14, and to solo his 90 hp J-3 tow plane at 17. By the time he graduated from high school, Troy had about 150 hours in the Cub and had already decided he wanted to become a professional pilot. He initially enrolled at Embry-Riddle in Daytona Beach, but later transferred to Middle Tennessee State University at Murfreesboro to complete his formal aviation education. While at MTSU he also worked in line service at an airport in Nashville and made a lot of connections in the corporate aviation world. After obtaining his Commercial license, CFI, multi-engine and instrument ratings, he got a job as a co-pilot on a Lear Jet and some turboprop aircraft. After building up sufficient time, he took a job flying checks at night in a Cessna 210 and Barons, averaging 110-120 hours a month for the next three years. Once his experience level qualified him for a left seat corporate job, he went to work for Tennessee Aluminum Processors and has been with the company for 10 years. He has subsequently obtained an ATP license and, just this past January, a seaplane rating.
Tennessee Aluminum Processors is one of the sponsors of Sterling Martin’s NASCAR Winston Cup stock car and one of Troy’s jobs is to fly members of the team to and from the race tracks on weekends. Sterling is having his best year ever and is battling with Jeff Gordon and Dale Earnhardt for the season championship, so Troy’s role is of vital importance to the team’s efforts. As varied as his flying experience has been and as much as he enjoys his job flying the King Air, Troy has always had a yen for pure sport flying.
RC models provided the scratch for that itch for many years (and still does), but eventually, perhaps inevitably, to build his own airplane. Like every builder, his choice of a design was predicated upon price, but beyond that his top priority was speed. Putting those two together, it was obvious to him that what he was looking for was the greatest amount of speed for the least amount of money, both in initial cost and in operating expense. As a first time builder, another major consideration was a type of construction he felt comfortable with...and something similar to his model airplane experience fit that bill. In Troy’s mind, all these considerations led him to the KR-2...and, eventually, to Sun ‘n Fun ‘95.
As we saw his KR-2, N100TP, at Lakeland in April, it was powered with a Revmaster 2100 that Troy had rebuilt, installing a forged crank, new pistons, cylinder barrels and heads and stock valves. Short stacks sold by Ken Brock Manufacturing were also used. A Revmaster cowling was the only premade airframe component used. An Ed Sterba 52" x 52" propeller created the thrust.
Most KR-2’s have bubble canopies, but Troy wanted something more like a cabin arrangement. He cut his bubble apart and used the pieces to make a fixed windshield and a canopy with a roof and left side gull wing door. He is 6’ 2", so he had to make the roof wider at the sides. With the stock rounded bubble, he would have had to have flown with his head tilted toward the center of the fuselage.
Back outside, all the control surfaces are balanced 100% and the airplane has what is surely one of the widest track landing gears ever in-stalled on a KR-2. Troy used the spring bar gear legs off a Sonerai I, cut them down to the desired size and welded up his own brackets to bolt them to the main spar. He made up his own wheel pants for the main gear wheels and the tailwheel by simply carving blocks of foam to the desired shape and glassing them. The pants are a very tight fit around the wheels to cut down on drag and he was a little concerned with the length of the grass in the parking areas when he arrived at Sun ‘n Fun in April.
Fortunately, however, it was sufficiently tromped down after the first couple of days so there was no longer a danger of getting the pants jammed up. The wings were built up essentially as per plans with foam and fiberglass over the wood spars. Troy used DuPont’s Centauri acrylic enamel to paint his KR-2 and was very pleased with it. "I found if you put a coat of paint on you weren’t happy with, you could sand it with 1,200 grit sandpaper and use some compound and you could get a shine out of it. I didn’t have to re-paint anything."
Troy had a weight reduction program going throughout the construction of his airplane, which included the omission of an electrical system. The prototype KR-2 weighed just 430 pounds in its original, very simple configuration and the stress analysis, sizing of materials, gross weight of 800 pounds and the resulting performance figures were all based on that modest number. N4KR originally had a basic instrument panel, sling seats with cushions and no upholstery, carpets, etc., with the result that it has been very difficult for subsequent builders, who want to add a lot of bells and whistles, to equal the prototype’s weight. Troy’s N100TP weighed 520 pounds, so he is much closer to the 480 pounds Rand Robinson Engineering recommends today than most KR-2 builders. With the current allowable gross of 900 pounds, he has a good usable load but says he has to watch the distribution of weight to keep the CG from moving too far aft.
We asked Troy for his performance numbers and he gave us a takeoff, climb and cruise scenario that also provides some insight into the flight management of a low powered high performance airplane.
"My engine will turn about 3,200 rpm on takeoff. I raise the tail as soon as I can and I rotate at around 50 knots (58 mph). 1 hold in ground effect until I hit at least 70 knots (80 mph), then I begin a shallow climb until I hit 120 knots (138 mph), which is my normal climb speed. That gives me about 1,000 fpm. You can climb steeper, but you have less visibility and the engine runs a little hotter. The way I do it, I think you cover a little bit more ground and you’re easier on your engine. When I level off, I let the engine wind on up and the air-speed come up as high as it will, then I pull the power back to about 3,200 and it will settle down to around 145-150 knots (167 - 173 mph). Wide open at, say, a 1,000 feet, it will do about 155 knots (178 mph). It carries 14 gallons of fuel and on one of the legs down here (to Florida) I flew 300 nautical miles and still had over an hour of fuel when I landed."
Now that he has completed and is enjoying flying his KR-2, Troy has been helping a friend restore a Luscombe 8A. He received a Repairman’s Certificate for building the KR-2 and is using the work on the Luscombe to fulfill the experience requirement for obtaining his A&P license. As is the case with most builders, he has a lot of friends, companies... including Rand Robinson, of course...and family to thank for help and encouragement on the project. First and foremost, he says, were his wife, Mona, and four year old son, Graeme, who loves flying and probably thinks his dad’s airplane is the coolest toy in the world.
BOBBY MUSE’STRI-GEAR KR-2
Bobby Muse of Murfreesboro, TN is a second generation KR-2 builder. His father, Bob Muse of Marietta, OA, completed a retractable taildragger version in 1984 and has been flying it ever since...in fact, he flew it to Sun ‘n Fun ‘95 in the company of Troy Petteway in his fixed gear taildragger and Bobby in his tri-gear KR-2. Bob, Sr. had soloed in 1938 as a result of winning eight hours of dual instruction in a model airplane contest, was an Air Force mechanic in World War II and was a civilian quality assurance specialist for the Air Force at Lockheed’s Marietta, GA plant when Bobby was growing up. Both were modelers, but both wanted to build a full-size airplane. The elder Muse had been out of flying since the start of World War II for the usual reasons, military service, marriage and raising a family, but was looking forward to eventually getting back in the air as a pilot. As events transpired, it was Bobby who took the crucial first step. In the early 1970s Bobby was working for Lockheed-Marietta, had his A&P license and thus was primed and ready to tackle a homebuilding project. His fuse was lit when he saw a picture of Ken Rand’s tiny KR-1 in an aviation magazine and he immediately bought the plans...set number 28, in fact. Shortly thereafter, however, he joined the Air Force and left the plans with his father. Bob, Sr. was more interested in a 2-place airplane, so he waited until the KR-2 plans were put on the market and a number of them had been built and flown. He began work on his KR-2, N28RM, in 1979 and flew it for the first time five years later.
Bobby, meanwhile, had learned to fly in a Cessna 150 in an Air Force aero club at Biloxi, MS. Knowing a transfer was imminent, he began flying almost every day and got his license in just 56 days...thanks to a last minute cash infusion from ol’ Dad.
"I was an enlisted man and didn’t have much money, so I ran out before I got my license. I would never have been able to complete the course if Dad hadn’t sent the money to finish it."
Bobby was shipped out the day after getting his license and didn’t fly again for five years. He was a computer specialist in the Air Force and pursued that line of work after returning to civilian life. He used his GI Bill benefits to keep his hand in flying for a number of years, but it was just enough to keep him legal to carry a passenger. He still had his dream of building an airplane, but it remained on hold until his father completed his KR-2 and he had a ride in it... then he knew he had just run out of excuses and simply had to get himself into his workshop.
Because he was a low time pilot with nose gear time only, Bobby decided to build a tricycle gear version of the KR-2. He had the sawdust flying almost immediately, but over the next 11 years the project would be a roller coaster ride of furious activity, interspersed with weeks and months when the only work going on in his shop was the spinning of spider webs. Five years ago, Bobby made a pact with himself that from that time onward, he would do some work on the project every day, even if it was nothing more than cleaning up the shop or laying out materials and tools for the next work session.
Soon, real progress was evident, which provided incentive to work even harder... and in June of 1993 the FAA was at his place inspecting and signing off the airplane for its first flight. As we saw it at Sun ‘n Fun ‘95, Bobby’s N122B is powered by a Revmaster 2100D with a 52" x 50" wood prop by Ed Sterba. The engine has dual mags and an electrical system that includes a Subaru starter. The fuselage fuel tank holds 18.5 gallons and is unique in that it is easily removable for access behind the instrument panel. It’s the best modification of the airframe he made, Bobby says. The instrument panel is molded fiberglass with the center radio stack extended out slightly to divide the panel in half. The flight instruments, plus the tach, are on the left and the engine instruments are on the right. A Garmin 95 GPS is mounted on the far right and is canted toward the pilot. The upholstery is trimmed in the same burgundy that is used in the trim in the exterior paint scheme. Like Troy Petteway’s KR-2, Bobby’s was built with a single gull wing door on the left side. He started out with a Super KR-2 canopy, which is a full bubble, and moved it around a bit to get it to flow into the lines of his fuselage the way he wanted it to. Then the cutout was made for the door, and the piece removed was used as the window. The rear deck was given a bit more of a concave shape than most KR-2’s, but the flat sided wood "boat" of the lower half of the fuselage limits the amount of sculpting that can be done.
N122B’s wings are essentially stock, but the integral center section has been extensively modified to eliminate the retractable gear and use a fixed main gear instead. A taildragger version of the KR-2 sits so low to the ground and is so small that many owners simply swing a leg into the cockpit to enter and never step on the wing at all. With a tri-gear that first step would be practical only for NBA centers and power forwards, so Bobby reinforced the upper left wing root area to allow standing on the wing for entry and exit. Wing tie-down rings were built in during construction, as were wing lights, but the latter have not yet been wired into the electrical system. The plan is to install strobes at a later date.
The original nose gear was Bobby’s design and it worked until he installed a wheel pant. The first time he attempted to taxi with it in place, the gear shimmied and failed. It was replaced by a Dan Diehl nose gear and no further problems have been encountered. The nose gear is a castoring unit and steering is by differential braking. The main gear wheel pants are from Rand Robinson and Bobby made his own nose gear pant. Bobby is as proud of his paint job as he is any other part of the airplane, especially so since it was his first effort. He read everything he could find on the subject, asked a lot of questions, then just rolled the airframe out into his driveway and painted it. He used a Ditzler paint system, from the primer through the finish coats, and found it to be very forgiving...very easy to correct mistakes. When finally satisfied with his work, he sealed it up with a clear coat. The N numbers are vinyl. N122B weighs 629 pounds, which is not excessive for a KR-2 with a tri-cycle gear and wheel pants, an electrical system, pleated upholstery, an armrest, gull wing door, a large baggage compartment, nice paint and such. When the airplane was finally ready to fly, Bobby had to take an honest look in the mirror and decide if he was as equally ready as a pilot. He had flown little during the long building period, and even less in anything comparable to a KR-2. With most of his time in a high wing Cessna, he decided to get a few hours in a Piper Warrior to at least have a low wing orientation. He flew with four different instructors in Warriors over a four month period and each of them told him he was 0.K. and to go fly his airplane...but he wasn’t as confident. He had begun taxi tests in the KR and literally wore out a set of tires trying to convince himself that the transition from a wheel to a stick wouldn’t be a problem and that all the hangar talk about the pitch sensitivity of small homebuilts was overblown. He progressed as far as long runs with the nose wheel off the ground and the ailerons obviously effective, but he still couldn’t commit himself to flight. Finally, after still an-other such run he admitted to his father, who was observing and talking to him with a hand held radio, that he just didn’t have the nerve to do it. "Dad said, ‘O.K., if you can’t do it, then I’11 do it for you.’ That did it. I said, ‘Oh, no you’re not!’ I hung up the mike and went flying...and I’ve been flying ever since. That was just the challenge I needed, and Dad probably knew it."
To his pleasure and relief, Bobby found his KR to be easy to fly and, with the tri-gear, easy to land. He had some initial cooling problems, which were solved by increasing the size the cowling outlet, and the aforementioned failure of his nose gear, but, otherwise, no engine, systems or air frame problems of any sort. Top speed, according to the GPS, is just over 150 mph with his current prop, and, without flaps to create drag, Bobby says he wants to be indicating about 40 mph at touchdown, otherwise the airplane will float forever. At Sun ‘n Fun in April, he had not yet carried a passenger in the airplane, but intended to creep up on the situation this summer by flying with increasingly heavy sandbags until he reached the 170 pound "average man" equivalent in the right seat. Bobby had already won the Best KR award for two years in a row at KR gatherings before he set out for Sun ‘n Fun ‘95 and, along with Troy Petteway, was planning this year’s event at their home base in Columbia, Tennessee (see sidebar). Two years ago, Bobby got into still another kind of homebuilding. Moving to Murfreesboro, TN (he lives in Antioch), he is now in the residential construction business.
ON TO SUN’N FUN
Several KR-2s flew together to Sun ‘n Fun ‘95, among them Troy Petteway, Bobby Muse and Bob Muse, Sr. Troy and Bobby departed from Columbia, TN and met Bob, Sr. at LaGrange, GA. About 25 miles out of LaGrange, Bob apparently hit a bird which took almost half the blade off one side of his prop. The airplane began shaking so violently that Bob could not read his instruments or use his radio, but he was able to maintain level flight at about 65 mph... which was fortunate because he was over a densely forested part of Georgia with no place in sight to make a forced landing. Realizing his father had a problem, Bobby punched in the "nearest airport" display on his GPS and proceeded to lead him in for a landing. After carefully checking out the airplane and determining that no damage had been incurred by the airframe that rendered it unairworthy, Bobby took his father’s car keys and flew back to Marietta, GA to pick up his spare propeller. Within a couple of hours he was back, the spare prop was installed and the KR’s were off and headed for Sun ‘n Fun once again.
"I got the GPS for my birthday," Bobby says, "and it’s probably the best thing I ever had. With the terrain we were over at the time, being able to get to the nearest airport quickly might have saved my dad’s life."
At Sun ‘n Fun, both Troy and Bobby entered their KR-2s in the Sun 100 air race, along with Steve Alderman and Martin Roberts. Steve finished 25th overall at a blazing 196.96 mph in his 0-200 powered KR-2; Martin, who also runs an O-200, was 36th overall at 176.95 mph; Troy was 38th overall and first in Class 1A for aircraft under 100 h.p. at 163.97 mph; and Bobby was 41st overall at 147.54 mph. Martin Roberts was credited with the win in Class 1A in the results provided to Sport Aviation at Sun ‘n Fun ‘95 in April, and those results were used in our Sun 100 coverage in the July issue. The information was in error; however, because Roberts’ 0-200 powered KR-2 was competing in a different class. Troy was the winner of Class 1A in his 65 hp machine.
A lot of bang for the buck was what Ken Rand and Stewart Robin-son had in mind when they designed the KR-1 and KR-2 two decades ago, and that’s just what Troy Petteway and Bobby Muse were enjoying at Sun’n Fun ‘95.