Beyond the Pitts

Reprint of: Beyond The Pitts
Sport Aviation, August 1992
by:Dan Rihn

BEYOND THE PITTS There is no way I could start this article without first giving my thanks to Curtis Pitts for designing one of the greatest aerobatic airplanes of all time...... thanks Curtis.

Dan Rihn and his Pitts Special

Twenty years ago this summer the Pitts Special swept the World Aerobatic Contest (WAC), american pilots came in 1,3,6,9, and 30 in the mens division, 1 and 10 in the womens division . They all flew Pitts Special aircraft . Charlie Hillard was named World Champion and Mary Gaffaney won the womens World Champion title , the mens team trophy was awarded to top three american pilots .

This contest was to be the ultimate achievement for the Pitts Special. After this event the Pitts Special went on to become the most popular aerobatic airplane in the world, either factory built , kit built or built from plans. No doubt about it the Pitts was here to stay . As in any motorsport the desire for more performance is a never ending objective . Through the years the Pitts Special has been modified , copied and redesigned in many ways , however underneath the skin lies the ancestry of Curtis's little biplane. This is a story of how I designed five different competition biplanes all based on the Pitts Special.

In 1972 I was a senior in High School logging as much time in our family Piper J-3 Cub as I possibly could. I had decided that I was going to become an aerobatic pilot someday and that I was going to fly a Pitts Special , even if I had to build it myself. I persuaded my metal shop instructor to teach me how to weld then I set off to build my Pitts Special. With help from my father the two of us built up a set of tail surfaces.

That was as far as that project got. In September I left home for college in southern California to become an aeronautical engineer. In '74 I convinced my parents that I should take the Cub with me to SoCal and to keep up my flying skills. I moved the Cub to Compton airport and fit right in with the homebuilders and antiquers on the field. As luck would have it I met up with Jim Young who was building a gorgeous Starduster TOO known as Big Red. Jim and I became very good friends and I began spending much of my free time helping him finish the Starduster. However I still had the bug to build a Pitts and spent countless hours telling Jim how he should have built a Pitts instead of a Starduster. During one of our marathon fabric sanding sessions on Big Red we decided that we would build two Pitts S-1S's in Jim's shop . Jim would later go on to win Grand Champion Homebuilt at Oshkosh in '75 with Big Red then promptly sold it so that he could concentrate on the Pitts project.

Jim and I each finished our Pitts, I was still in college and Jim was a far better craftsman than I so naturally he was in the air before me. We then started going to the regional International Aerobatic Club (IAC) contests , it wasn't long before Jim was bitten with quest for more performance. It was about this time that Kermit Weeks was really making some waves with his own design based on the Pitts. The Weeks Special (S-1W) was powered with a 200 HP Lycoming driving a two bladed Hoffman propeller. Kermit was flying circles around any stock Pitts. There were many other competition pilots modifying their Pitts but what really turned Jim and I on was that this was not a modified Pitts but a completely new design based on the proven Pitts formula.

Jim Young and the Sunbird, winter 1980

In early '78 Jim and I decided that we would design our own new aerobatic airplane and attempt to do Kermit one better by using a 260 HP six cylinder Lycoming engine. Hence the S-1X Sunbird was born.

I did all the engineering and drawings, Dave and Larry Massey did all the major welding, Jim purchased stock S-1S wings,horizontal tail,elevators, and spring gear from the Pitts factory. From the nose to tail this was a very different airplane. We used a stock Lycoming O-540 with a PS-5 carburetor driving a two blade 80"diameter Hartzell prop. The compound curve cowl was made up of several pieces of aluminum , we made up a "hoop skirt" type mockup of the engine then had a professional metal shaper bang out the shape on a yoder hammer. The finished product was a beautiful 2 piece that had most people convinced it was made from fiberglass, the finished cowl weighed only 12 pounds.

We made our own mold for the canopy using foam and fiberglass, a local windshield/canopy maker used the mold to pull a single piece canopy for us.

We designed our own control housing that fit under the seat, a very low profile affair that helped us get rid of the pot belly look usually associated with Pitts.

The ailerons were also our own design, symmetrical in shape and larger than on Pitts. We paid extremely close attention to weight control, not one part went into the airplane without being thoroughly looked at as to its degree of structural integrity versus weight. Most parts were laboriously lightened. Jim was a Dentist by profession and I was always amazed to watch him work with a high speed rotary file, he could reduce the weight of just about any part and still retain the strength. All of this extra labor paid off in the end our empty weight was 854 lbs, or about 100 pounds more than light S-1S's. Overall dimensions were 16.4 feet long, 17.3 foot wing span and a total wing area of 102 square feet. It took us eighteen months to first flight and it was obvious from the first takeoff we had a real performer. With a competition weight of 1090 lbs and a power to weight ratio of only 4.19 lbs/HP the Sunbird had a climb rate of 4,100 feet/min.. From an aerobatic performance viewpoint the Sunbird was capable of 2,600 feet on a vertical up line in a Hammerhead and had the ability of capturing 1,800 feet after a vertical up maneuver and flying away. The top speed was a 205 MPH in level flight.

Jim made his competition debut in the Sunbird while flying in the Advanced category at the Delano aerobatic contest in September of '79. Later in October the Sunbird was the hit at the Nationals in Sherman Texas. From the very start of the Sunbird project we had our eye on building a few more for other competition pilots. During the Christmas holidays we sat down and started re-engineering the Sunbird to fix some of the small things we had not liked on the prototype. The main problem was that it was a little nose heavy. I reworked the fuselage and moved the wings further forward and the pilot a few inches aft. We also wanted to use a lighter 3 blade prop from Hoffman. By March of '80 we were well on our way to starting up another project when disaster struck.

Dick Green and his S-1X Sunbird

While flying to Delano to deliver the new fuselage drawings to the Massey's, Jim became caught in a storm over the Gorman pass. Low ceilings,poor visibility and blowing snow forced him to attempt a landing on the highway at the foot of Mt.Pinos. Jim ended up under shooting the highway by a few feet. Unfortunately, there was a creek which made a vertical embankment at the edge of the road. The sudden impact totally destroyed the Sunbird and killed Jim. This was devastating for me to lose my best friend so needlessly. The lesson I learned from this experience was obvious. The very next day, when the Massey's and I went to the crash site the sky was clear with visibility over 100 miles. From that point on, I have never found myself in such a hurry that I had to be anywhere .

I didn't do any design work for anybody for several years after this accident. Mostly I modified my own S-1S and kept competing. During this time period I met many wonderful people and fellow competitors. I did decide to sell drawings of the Sunbird,and eventually sold three sets of plans. Tom Aberle, of Sport Biplane racing fame, bought a set and started building. This project was eventually bought and finished by Dick Green. Dick is currently practicing for airshows and competition. Another set of plans was purchased by Kenny Blalock who used them for the basis of his own design now known as the Pitts Falcon. Ultimately I decided to stop selling plans and only do design work for my close friends.

The Dick DeMars-built 8-cylinder Lycoming IO-720 engine for
Awesome Lady. The stock IO-720 was modified to use
parallel valve cylinders with a compression ratio of 11 to 1.
The estimated power output is 460 hp.

Awesome Lady's 4-blade propeller
built by Gerd Mulbauer, MT-Propeller

At the '83 National aerobatic contest in Mesa, Arizona two of my good friends, Amos Buettell and Mike Anderson talked me into designing new airplanes for each of them. Here again it was the influence of Kermit Weeks that got the wheels rolling. Kermit was now flying the Weeks Solution, another new biplane with 300 HP. Kermit was the hit of the contest and won the National title. Both Mike and Amos wanted something that could match or top Kermit. Mike had something along the lines of the Sunbird in mind but with even more power. Amos wasn't sure what he wanted so I came up with the idea of using a IO-720,eight cylinder, 400 HP, 4 blade propeller mounted on a S-2 size airplane. Amos was sold on the concept and contracted the services of noted Pitts builder Rich Bastian to build the airplane. Mike and I exchanged ideas until we were sure what we were after. By the Spring of '84 I had completed drawings for both airplanes. Rich got started immediately and Mike decided to build his airplane himself. From that point on Mike's plane became known as the Phoenix and Amos's was called Awesome Lady (all of Amos's airplanes were named "something"Lady). The name Phoenix was chosen because Mike wanted to symbolize the uprising of the Sunbird project.

Awesome Lady was truly awesome, Dick Demars built up the engine,we decided to modify it quite a bit from the stock IO-720. We used the lighter parallel valve cylinders and upped the compression ratio to 11 to 1,this along with other modifications which raised the output of this engine from 400 HP to 460 HP. Gerd Muhlbauer built up two 4 blade propellers, one for a spare. Fairly stock S-2 wings were built up by Dan Beckman however he made them much lighter and they had larger ailerons. The fuselage was pure Pitts in design, basically what I did was follow what the Pitts factory did to the S-2A when they went from a 200 HP 4 cylinder engine to the 260 HP 6 cylinder engine. The only difference was, I used the S-2B as my starting point. The "B" uses a 260 HP 6 cylinder engine so all I did was shift things around to accommodate the weight of two more cylinders.

The building of Awesome went very quickly, in twelve months time she was very near making first flight. Then disaster struck, someone broke into Rich's shop and vandalized it by setting it on fire. Several of the aircraft in the shop were destroyed, the wings of Awesome were reduced to ashes but the fuselage's damage was primarily limited to the fabric and the canopy. Amos was absolutely heartbroken, he decided to continue the project and rebuild Awesome Lady.

In order to have something to compete in for the '85 contest season he the purchased a Laser monoplane . Unfortunately it wasn't very long before tragedy struck again. While practicing in the Laser a propeller counter weight broke lose. The vibration was severe enough to eventually cause an in-flight fire. Amos was too low to bail out and too high to get on the ground quick enough. While attempting to land the burning aircraft he lost control on rollout, groundlooped and flipped over. Some people pulled him from the burning wreckage but Amos was not able to survive the damage done to his body. Again I was devastated with the loss of yet another very close friend.

Not much happened to the Awesome Lady project until Bob Veazie decided to buy it from the Amos's estate. Awesome Lady was rebuilt and finally took to the air in May 1987. The performance of this plane lives up to its name. Bob described some of the performance as follows," on an 85 degree day at Phoenix, Deer Valley airport (field elevation 1475 MSL) I started the stopwatch at brake release, 90 seconds later I was at 6400 feet MSL and doing slightly better than 200 MPH".

Awesome Lady XP 720

Perhaps the most impressive maneuver it will do is the Torque Roll, the roll rate is as fast or faster going back down than it is going up. Bob found that it was the easiest airplane he had ever flown to hold in the vertical line while coming back down in the Torque Roll. I often wonder what could have been if Amos were to have competed in it, Amos was well known for his extremely aggressive and imaginative 4-Minute Freestyle sequences. Awesome Lady is now owned by Bob Sears,Bob is planning on flying it in airshows and setting some time to climb records.

Some of the specifications for the Awesome Lady are ; wingspan 20 feet ,length 19 feet, empty weight 1380 lbs.. The top speed in level flight is 230 MPH with a cruise speed of 175 MPH. The noise of the 8 cylinder engine and 4 blade propeller is like no other aerobatic airplane. This should be a real crowd pleaser at airshows. Needless to say Bob Sears should have no trouble breaking some time to climb records in a more ideal conditions than Bob Veazie had in Phoenix, Arizona.

A size comparison of the Phoenix and the Goshawk

Meanwhile Mike Anderson continued building the Phoenix. Mike had originally wanted to build 4 or 5 airplanes but soon decided that he should build one first then see how it flew.

This project progressed slowly in the early stages. This was due in part to Mike modifying his flat wing Pitts by building a set of symmetrical wings for it. Also during this time I became friends with Rory Moore, an Unlimited competition pilot flying a stock Pitts S-1T. Rory was based in Phoenix, Arizona, and routinely practiced in 100 degree + temperatures and very high density altitudes. The stock S-1T was really struggling in these conditions. I might add that Rory is a big man and weighed over 240 lbs at that time . This put him at 1200 lbs aerobatic weight with a wing loading of almost 12 lbs/sq ft.and a power loading of 6 lbs/HP. Watching him start an Unlimited sequence in these conditions was like watching the Space Shuttle returning to earth. At the '85 Nationals Rory talked me into designing a new biplane. He wanted something designed around his large frame with performance and looks comparable to Kermit Weeks Solution.

The Goshawk just prior to first flight.
Another Dick DeMars-built , highly modified Lycoming IO-540.
This angle valve engine put out 345 to 350 hp on the dynamometer.

After returning home I started designing what was to become known as the Goshawk. Due to the excellent working relationship I had developed with Rich Bastian I convinced Rory to hire Rich Bastian to build and coordinate the construction of the Goshawk. Again we hired Dick DeMars to build the engine and Dan Beckman to build the wings. The building went very quickly , on January 25, ' 87 the Goshawk took to the air, this was only 13 months after the project was started. Rich had truly built a masterpiece this time, the joke was that if Rory couldn't win at the aerobatic contests he could easily win a trophy at a fly-in.

The Goshawk weighed in at just under 1100 lbs and is powered with a pumped up Lycoming IO-540, which had a dry weight of 410 LBS, with a compression ratio of 10 to 1 it is capable of producing about 345 to 350 HP, a tribute to Dick DeMars expertise. During the construction period Rory went on a serious diet, he is now a muscular 210 lbs, this put the competition weight is about 1400 lbs making for a power loading of just 4 lbs/HP. The overall dimensions are 18 feet long and a 19 foot wingspan , both upper and lower wings are swept back 7.5 degrees with a wing area of 124 square feet. A great deal of attention was paid to keeping the lines a more angular shape than the Pitts, this was done to improve the judging. The current monoplanes have benefitted greatly by presenting a straight,clean angular shape to the judges. Also, Rory designed the paint scheme to enhance this effect, the overall presentation to judges is a very clean silhouette. The performance of the Goshawk is as stunning, taking a back seat to no other aerobatic airplane. It wasn't long before Rory developed into a serious contender for a coveted spot on the U.S. Aerobatic Team. To this date Rory has won or placed in many regional contests and the highest place achieved at National contest was 8th in 1988.

The Goshawk is capable of performing 5 vertical rolls with relative ease, in his 4-Minute or airshow routine Rory has done Torque rolls with a total roll count as high as 13. Some of the other maneuvers Rory has developed in his 4-Minute routine are vertical Lomcovaks that transition into a torque roll, knife edge spins, a maneuver known as the Cartwheel (or also known as the Pinwheel) which is a total 540 degrees of yaw rotation at the top of a vertical line. Another unusual maneuver made possible by the high power to weight ratio and the large rudder area is the ability to recover from a flat spin without dropping the nose,(just use full power and lots of opposite rudder). Currently Rory and the Goshawk are based in the San Diego, CA area at Montgomery Field.

When Mike Anderson saw how quickly Rich Bastian had built the Goshawk and how beautiful it turned out he decided to hire Rich to finish the Phoenix. This proved to be an excellent decision. Once again Rich performed his magic and created a gorgeous machine. Rich and his gang started on the Phoenix in early '87. They nicknamed the project "Ol' Rusty",to this day they probably refer to it with this name. Rich would keep Mike abreast with the progress with occasional video tapes. These tapes would do wonders for Mikes spirits.

The Phoenix is somewhat smaller than the Goshawk and bears many resemblances to the Sunbird. Wing span is 17.33 feet, wing area is 102 square feet (including the fuselage area) and the length is 16.5 feet. The empty weight turned out to be 1023 lbs and the competition weight is 1280 lbs. Powered by a pumped up Lycoming IO-540 capable of putting out 350 HP and driving a 3-blade MT propeller the Phoenix has a power to weight ratio of 3.7 lbs/HP.

Mike Anderson and the Phoenix shortly after
placing 2nd at the 1989 Nationals

The first flight was in May '88. Mike spent about 150 hours in flight test and learning how to get the most performance out of the Phoenix. The top speed in level flight is 205 MPH and the stall speed is 80 MPH, it has an unbelievable acceleration rate and can climb at 4,000 feet per minute. Dive test have been made up to 250 MPH indicated but in a sequence speeds are kept down to 220 MPH. The roll rate is an honest 360 degrees per second and the stick pressures are very light making point rolls a delight. Mike can easily perform 6 linked vertical rolls and has done as many as 15 total rolls in a torque roll. From level flight at 100 MPH Mike can pull to vertical do a full roll then fly away upright (cap off). However it is snap rolls that are the Phoenix's forte', These are performed at approximately 140 MPH. During Mikes 4-minute sequence he does 3 linked vertical inside snaps. The spin characteristics are traditional and no surprised have come up other than that in an inverted flat spin with full power the nose pitches from almost straight up to nearly straight down. However if a little power is taken off it will flat spin just like a Pitts, which means very acceptable and honest flat spin characteristics. Recovery from any type of spin can be accomplished by just using opposite rudder only, the Gene Beggs method of power off, hands off, opposite rudder also worked beautifully. Visibility over the nose on the ground is not real good, somewhere between an S-1S and an S-2B, visibility in the air is quite acceptable for an aerobatic biplane. During an aerobatic sequence the fuel burn rate is 30 GPH and 15.5 GPH is the normal burn for cross country.

Rory Moore on his first flight in the Goshawk at
Rich Bastian's private airstrip.

It wasn't long before Mike started inventing new maneuvers and exploring the outer edges of the envelope. The Phoenix is capable of doing every thing the Goshawk is and, combined with Mike's own inventiveness many new maneuvers were created which made for an outstanding 4-minute routine. This sequence includes a Cartwheel, Knife edge, torque roll, fly away humpty bump, shoulder roll, and many other yet to be named convolutions.

Much of the same thinking went into the Phoenix as did the Goshawk in respect to the judging aspects. Mike designed the paint scheme and the effect has proven to work marvelously. The white on the fuselage bottom contrasts sharply with the black top side, this makes the airplane look much longer in the air which makes for easier judging. I really had a ball watching the Goshawk and the Phoenix go head-to-head in competition. I found it amusing to hear some people say that the Goshawk was too big and the Phoenix was just the right size, then I would hear exactly the opposite comment from someone else. My opinion is that they are both just right. The differences were designed and built exactly as their owners wished.

During the '89 contest season Mike would win every regional contest he entered including Fond du Lac. Later, at the U.S. Nationals ,only 25.034 points out of over 13503 points possible separated Mike from winning and placing him second to reigning national champion Clint McHenry. A 0.2 percentage of points made the difference between first and second place, however this assured Mike a position an the U.S. Aerobatic Team and therefore a trip to the '90 World Aerobatic Contest to be held at Yverdon, Switzerland. Unfortunately this trip was not to be, due to commitments at work he had to give up his spot on the team to the alternate pilot and good friend Pete Anderson. Pete would go on to become the highest scoring U.S. pilot at the World contest and also win the Nationals that year.

Cecilia Aragon and the Sabre - May 1992,
after the installation of the Zivko wing.

Recently, I designed an I0-540 powered mid-wing monoplane for Rory Moore, sort of a Laser/Extra/Superstar clone but with a larger engine. However there is still a whole lot of knowledge from my Pitts experience built into this monoplane. Rory hired Alan Geringer and Rick Kunkle to build and coordinate the overall construction. Wayne Barton was hired to build the wing. Half way into the project, Rory decided to sell it to Cecilia Aragon. Rick and Alan did a splendid job of finishing up the Sabre as it is now known. At the '91 Nationals Cecilia won a spot on the U.S. Aerobatic Team entitling her to fly in the '92 World Aerobatic Contest to be held in LeHavre, France this summer. Hopefully Cecilia will fly the Sabre in this contest and I can finally say that one of my designs made it to the World Contest. In summary, I would say that I have had a most enjoyable experience designing these airplanes. I've been asked by many people which one I personally like the most? I really can't answer that because I have good thoughts about each of them, I think that it would be similar tho answering which one of your children you love the most. I have also been asked how come I don't build one for myself? The answer to this is much easier, pure economics and time (or lack thereof). Fortunately for me, I have had the good fortune as an aircraft designer to have such wonderful friends who believed in me enough to build aerobatic airplanes of my design.