Building and Flying a RANS S-10 (30kb)

I always wanted to build and fly my own plane, but it wasn't until a real friend took me flying and let me take the controls for most of a two-hour flight that I finally believed I could do it. Or at least, at that point, I believed I could learn to fly. Once I believed I could do it, I had my license in just over four months. After that, it wasn't very long before I started thinking about what kind of plane to build, and a short ride in a Curtiss P-40, complete with a series of very rapid rolls, convinced me that it had to be aerobatic.

As I learned about the cost of Lycoming engines and parts, I became convinced that whatever I built would have to be powered by something else. A review of the alternatives left only the Rotax as a viable alternative. Except for VW's, there were not enough of any one type of auto engine flying to assure me that their reliability was acceptable. I felt that a VW wouldn't work because its power-to-weight ratio wasn't good enough for aerobatics.

After reviewing the Rotax-powered kit planes on the market (this was 1987), I found that there were only two aerobatic alternatives: the Murphy Renegade and the RANS S-9. The Murphy had a good reputation but had open cockpits and was intended only for mild aerobatics, while the S-9 had a canopy and was intended for competition aerobatics. Besides, the S-9 was a monoplane, and I liked that; it reminded me of the P-40!

The only drawback to the S-9 was that it was a single-seater, and I knew I'd want to take friends for a ride sometimes. But the magazine article which had reviewed the S-9 in glowing terms had alluded to a coming two-seat version, so I called the RANS factory and spoke to Randy Schlitter, the designer and head honcho. He said the prototype of the two-seater, called the S-10 Sakota, would be flying in a few months. Since the S-10 used the same wings as the S-9, I could order a wing kit immediately and start building even before the prototype flew.

I knew right away that this was my airplane, despite the risk entailed in buying a kit before the prototype had flown. I rationalized this by figuring that the S-9 was such a good airplane that the S-10 had to be fine, too. Awfully risky, I know now, but as it turned out, I was lucky.

The wing kit arrived in January, 1988. Naively, believed I could build the plane in the time quoted by the factory: 300 to 500 hours. I expected to fly my airplane to Oshkosh that summer! But I found building an airplane to be very different from tinkering with cars, which comprised the bulk of my previous experience with tools. The rest of the kit arrived on Memorial Day, and I was still working on the wings.

Weeks stretched into months, and then years. I learned some valuable lessons: touch the airplane at least 3 times a week. And break the project down into many small tasks. Whenever I tried to think of what was left to complete the entire project, I would get overwhelmed, and feel like stopping. But if I went downstairs, and concentrated on making one little part, or putting together some small assembly, I would find it manageable and quite rewarding. I'd get the satisfaction of completing another small project each time.

Touching the airplane three times a week kept me connected with the project. I always assured myself that if I didn't want to work on it that day, I'd touch it, and then turn around and go back upstairs. But I only did that once. Most of the time, I'd start cleaning up the workbench, or just put a clamp on somewhere, or drill one hole. One thing would lead to another, and before I knew it, an hour or two would have gone by, and I'd have another little project completed.

I found that I enjoyed working with aluminum. I found its cold silvery brightness pleasing to feel and look at, and it was easy to work with a file or a hacksaw, not much harder than wood. It was delightful to start with a raw piece of aluminum, and a little while later have a nice finished part, smooth and rounded and pretty.

Working with steel (mostly 4130) was more difficult. It was much harder, and not as pretty, either. I had to learn to use cutting oil and cobalt bits to drill it. Luckily there was not as much drilling or cutting steel to do in the S-10.

I loved bolting things together. I loved the cold hard feel of the AN nuts and bolts, and feel of the wrenches and sockets I used to put them together. I loved the rich golden color of the cadmium-plated AN hardware, and the silvery gleam and the solid clank of the tools as I worked. I found a special satisfaction each time some assembly was completed, and would often sit back and gaze at the results of my labor, as if I was viewing some exquisite work of art.

Always a reluctant seamstress, I dreaded the fabric work, but once I started I found it to be the most satisfying part of the project. I loved draping the fabric over a structure, and gluing it up, and then heat-shrinking it. It was delightful to see the fabric tighten up until all the wrinkles were gone, and see it form into gracefully rounded shapes, all pristine and white and beautiful. This part of the project was the most contemplative; as I worked, I would often sink into a kind of peaceful trance, hours passing by unnoticed as I cut and glued and ironed.

Painting, by contrast, was my least favorite part. It required a great deal of careful preparation of the surfaces, and was physically hard work, for I found I must keep the gun exactly the same distance from the surface, and move at an exactly constant rate, in order for the paint layer to be consistent in thickness. This was hard on the muscles, requiring a kind of steadiness that led to sore muscles and sometimes cramps. Disaster was always just one slip away; get a little too close, or drag a hose over a part, or bump it with the gun, and it would be ruined. Cleanup was no fun, either. But I must admit that the results were very rewarding indeed.

One of the most memorable moments was the first time I fired up the engine. The mighty Rotax roared for the first time just over 3 years after I started the project. I can remember the blast from the prop whipping my hair and sending the grass behind the plane into waves like a tiny windstorm.

When I think of it now, I am amazed at the amount of things I learned, from how to drill a hole to how to design and install an entire electrical system. Building this airplane was one of the most rewarding and educational experiences of my life. It beat college all to hell!

Eventually, after 3 1/2 years, the time came to make the first flight. So much has been written about the emotion of the first flight of a homebuilt, I won't attempt to add to that body of writing. I will say that I was totally focused on the early flights being uneventful and entirely lacking in surprises. Between this and the anxiety of flying a new airplane in which I'd invested 3 1/2 years of my life, I didn't really feel a lot of elation. It took some time until the newness had worn off and my anxiety had decreased before I could really feel the satisfaction of what I'd accomplished. Actually, the greatest satisfaction came a couple of years later after I'd had time to develop the airplane into a really capable performer, without the little bugs and distractions which it had at first.

My preparations for the first flight included taking a commercial flight out to Kansas to get some time in the S-10 and S-9 prototype. Randy Schlitter didn't know it at the time, but when he sent me up in the S-9 and I did a few loops and rolls, it was my first time doing aerobatics solo! I had a great time, and, more importantly, I knew what to expect when I began to fly my plane.

I also hired a DAR (Designated Airworthiness Representative) to do my inspection, instead of waiting for the FAA to get around to it. This cost $275, but it had the advantage of having a very experienced aircraft mechanic thoroughly examine my airplane. My DAR had been working on airplanes since before I was born! Very reassuring. He gave me a high compliment: he said that usually he has a long list of things that need to be corrected, but I had only three or four. It was great for my peace of mind to know that such an experienced pair of eyes had reviewed my work, and approved.

The first flights did turn out to be uneventful. The only scary thing (which I found on the ground, fortunately) was a broken prop bolt, a result of bolts which were too long and bottoming on the flange instead of properly clamping the propeller. My EAA advisor, Joe Gauthier, kindly flew up to New Hampshire from Connecticut with a replacement set. I asked him if he would like to take the S-10 up, and he accepted. He was very gracious in his analysis afterward, but I suspected that he found the airplane's lightning-quick pitch response and raucous, high-revving Rotax engine distinctly less appealing than the characteristics of the more conventional airplanes he was used to flying.

As an aside, I must say that I could never have built the airplane without Joe's help, and the help of others like him. The local EAA chapters provided a vital support system, both in terms of knowledge and skills needed to build the airplane, and in terms of emotional support and other forms of guidance. It is hard to express how encouraging it is to go to meetings and hear other people talk about their progress, or to actually visit a project under way. I found it to be equally encouraging to see the completed projects flying out of local airports, and sometimes I even got to ride in them!

A few hours into the test program, I did my first loops and rolls. Now that was exciting! Actually doing aerobatics in an airplane I built myself was an incredible reward for all the hard work and perseverance. Doing a hammerhead, my favorite maneuver, felt fantastic. I think this was the first time (of many) that I shouted with delight while flying the airplane.

My first contest was an experience of highs and lows. For various reasons, including tweaks to the plane which took longer than planned, it was over two years after the first flight before I flew in a contest for the first time. The contest was 200 miles from home, at Orange County airport in Montgomery, New York. The flight to Montgomery was in itself an adventure. With its screaming little two-stroke, the S-10 cruises at only about 100 MPH at just under 6000 RPM.

Before I flew the airplane, I got to know some ultralight pilots. I thought this would be useful because I could learn from them some of the subtleties of operating 2-stroke engines. I did. The first thing they told me was, "Don't worry about what you will do if the engine quits. Worry about what you will do when the engine quits!"

With this in mind, I always tried to fly with at least one potential landing site within gliding range. Flying west over unfamiliar territory, this just about committed me to flying along interstates, where I could land on the median or even on the roadway if there was no field within range.

I haven't said much about the flight characteristics of the S-10 yet. It flies well, but one of its characteristics is mild divergence in pitch and roll. In calm air, it is a delight. But in the mildly turbulent air which is typical during the middle of the day, it must be flown constantly. You can't let go of the stick for more than a second or two, because the airplane will start to climb or dive or roll off one way or the other. It's like flying on the head of a pin. I once counted my stick movements during one minute, and I made more than 60 movements in 60 seconds!

Looking for landing spots and keeping the airplane straight and level, not to mention navigating, doing the radio work, and scanning the instruments (especially the all-important EGT gages) turns out to be a pretty full workload. At 6 gallons per hour, with 13 gallons on board, the plane can manage just about 2 hours between refills. This turns out to be just about my limit, too; by then I need a break from the heavy workload and the stress of worrying about how I will handle things if the engine quits.

It turns out that the Rotax is not very happy on a diet of 100LL; the high lead content of this stuff fouls the plugs. Having mostly used auto gas to this point, however, I didn't know this, so I stopped at what I thought was Southbridge airport for a fill-up, bursting with pride to have gotten that far without any problems. I departed happily an hour or so later, after having mixed my 2-cycle oil in the fuel, and zoomed contentedly onward, following what I thought was I-84 west towards Hartford. I didn't realize that I'd actually been at Oxford, Massachusetts, and I was now following I-395 south towards Norwalk.

By the time I figured this out, I was halfway to Norwalk, and had to amend my route to take I-86 west to Hartford. I refueled again at Waterbury-Oxford, Connecticut and headed west, glad to be within a full tank's range of my destination. But the steady diet of 100LL was beginning to take its toll, and the engine seemed just a little rougher than normal, and it seemed a little less spritely in climb than usual. I put it down to just my imagination, but by the time I arrived at Orange County (with a big sigh of relief) it was clearly not running normally. It died when idling as I taxied in to the ramp. Slowed by 35 MPH headwinds and by my little detour towards Norwalk, I'd taken over 3 1/2 hours of flight time, and a good part of the day, to make the 200 mile trip.

My elation at having accomplished my goal of arriving at the scene of the contest was overwhelmed by my concern that I might have damaged the engine. After some thought, I realized that the lead had probably fouled the plugs, and possibly the rings. Replacing the plugs was not too difficult (if I could find some) but the thought of doing a ring job away from home was mighty intimidating.

Help from a local A&P, who picked up some plugs at an auto parts shop on his lunch hour, got me back in the air, and I was very reassured to find that the engine ran normally again. The rings were fine.

The rest of the weekend was the best of times and the worst of times. I met a lot of wonderful people, and I had a lovely flight in my first sequence in competition. I felt as though I was "in the zone" as I flew the Sportsman sequence. I was ecstatic when I landed, and was congratulated by one of the members of the US Aerobatic team, Diane Hakala, and many other people, for the quality of my flying in my first contest.

Concern about the engine, however, had distracted me (as did, I am sure, first-time jitters) and I'd forgotten the hammerhead. When I realized this, I was hugely disappointed. Then I had a close call when someone started an engine while I was standing very near its prop, and finally an unkind remark by a contest official put my mood into a tailspin, and I left for home almost in tears.

The flight home, at 7500 feet with a 35 MPH tailwind, was quite uneventful. I was able to make it home nonstop, with no more distress than some chilly toes and a full bladder. I landed back at home at Hampton Airfield, in the soft yellow light of the setting sun, with the voice of a good friend welcoming me back over the radio. I felt the glow of satisfaction which comes from successfully accomplishing a long-held, hard-won goal. I was home after competing in my first aerobatic competition in a plane I had built myself. This was a moment I will not soon forget.

That winter, I had a quite lovely trip to Plymouth, 90 miles south, for a practice contest. It was a delightful time, and I flew in company with a Cessna 150, which proved to be an excellent traveling companion, with almost exactly the same cruise speed as my S-10. I placed in the middle of the field in the single Sportsman unknown flight.

This and other shorter trips increased my confidence, and I entered two contests the following year, also in the Sportsman category. These again proved to be emotional experiences. At Orange, Massachusetts, I flew well but made some technical errors. In the first flight I again forgot the second maneuver and as a result, zeroed every one after it. I started the second flight outside the box and zeroed the first 5 maneuvers. However, I did fly well: had I been able to keep my scores for the second flight, my total for that day would have been four percentage points higher than the victor in the Sportsman class.

This was encouraging. I mentioned earlier that an official at my first contest had made an unkind remark. I had never heard of the IAC achievement awards at that point, and several people suggested that I get a form and apply for them. I thought this would help ease the disappointment of the forgotten hammerhead. But when I took the forms to the contest director for her signature, she harshly refused to sign it, saying the awards were not for those who forgot a maneuver. I was crushed.

Anyway, during the summer after the Orange contest, my local IAC chapter (chapter 35) organized a "Fly for Patches" event at Littlebrook in Maine. I participated and was able to earn smooth patches for Basic, Intermediate, and Sportsman all in one day. I found that, without the pressure of completing each maneuver inside the box and in rapid sequence, I was much calmer and was able to fly the maneuvers much more competently. I got a number of compliments, particularly on the snap rolls, and even got some 10's on one maneuver!

My confidence boosted by these positive experiences, I was determined to fly a clean sequence in the final contest of the year, at Orange County, NY. This time the flight down was uneventful mechanically, but weather socked me in at Oxford, CT, for two days. I was fortunate to arrive in Orange County on the last day of the contest, in time to fly my Sportsman sequence, and I did do it clean, scoring mid-pack for my best result so far. The return flight was almost a carbon copy of the year before, but a little warmer and more comfortable. Also, I was able to follow a straighter route because I had my new GPS on board.

All of this was immensely satisfying, and I was looking forward to a full season of competitions this year. Unfortunately, a month later, fate intervened. I replaced a minor part in the fuel system during my annual condition inspection, and this new part apparently uncovered a subtle design flaw in the aircraft's fuel system. On the second flight after the annual, the engine starved of fuel and seized on takeoff, and my little plane and I went into the trees. I walked away, but the aircraft was totaled.

* * *

Building and flying my RANS S-10 was the biggest and most satisfying accomplishment of my life. As you might imagine, coming to terms with its loss has been dreadfully painful, and I am struggling with it still. But it did lead to the opportunity to fly a Pitts, with one of the best aerobatic pilots in the country, Michael Goulian, and that has given me the chance to compare my S-10's flight characteristics with both Pitts and Decathlon behavior.

When I first flew the S-10 prototype, the predominant impression I had was how hard it was to control in pitch. I found myself performing PIO's while just trying to fly straight and level. After I completed mine, I let many other pilots take the stick, and there were very few who didn't do this at first.

The S-10's stick forces are extremely light in pitch, giving very little feel. It has a very powerful elevator, and it is actually slightly divergent in pitch. I found that if I trimmed up for straight and level, and nudged the stick either way, it would keep going until I grabbed the stick and brought it back to level.

By contrast, the stick forces in roll, while light just off-center, are fairly high near full aileron deflection. It takes a lot of muscle to get the stick all the way over at 100 MPH. Also, the S-10 is slightly divergent in roll.

The rudder is the nicest control. It is light and powerful, with very good feel and nicely linear response. The aircraft has very good yaw stability. On the ground, it is also very responsive, although the cable-operated mechanical brakes require a lot of effort and don't provide much stopping power.

The imbalance between light elevator and heavy ailerons made rolling maneuvers a challenge. I found it difficult to push very hard on the stick to the side without moving it fore and aft at all. Things improved when I added an electric starter and battery, because this moved the CG forward and reduced the pitch instability and increased the pitch stick forces slightly. Aileron spades helped as well, by reducing the stick forces in roll. With these changes in place, the plane was considerably easier to fly, and much nicer for aerobatics.

Its flight characteristics combine to make the S-10 very easy to land, and a delight in calm air once you've adapted to the control forces and responses. But as I said before, in the moderately choppy air often found on typical good flying days during the middle of the day, it has a fairly high workload. Combined with the need to look out for landing spaces, this makes cross-country flight fairly tiring.

The engine is what really differentiates this airplane from most aerobatic airplanes. The 2-stroke, 65 HP Rotax 582 screams away, with a 6800 RPM redline. I was fortunate enough to figure out how to make the RANS-supplied Mikuni pumper carburetors work, and so was able to fly sustained inverted for as long as I wanted (the size of the header tank would allow about 15 minutes).

The relatively narrow power band of the Rotax made it a handful with the original wooden propeller. The prop was pitched to provide good climb (about 1400 fpm solo) but was too fine for cruise. The engine was too lightly loaded in level flight, and this made aerobatics a challenge, because the instant the nose dropped below the horizon, the engine would zing towards redline. The airplane could easily overspeed even in level flight at wide throttle settings. The fastest I could cruise at a reasonable RPM was about 85 MPH.

Also, the light loading in cruise made it difficult to keep the mixture in the proper range. Often the EGT would creep dangerously near the redline, especially in descent, I think because the RPM's being turned were at too narrow a throttle setting relative to the design fuel flow characteristics of the carburetors. Consequently, the carburetors were not metering enough fuel to the engine.

All this changed when I switched to a Warp Drive High Aspect Ratio prop. This prop transformed the airplane. It is made of carbon fiber and is ground adjustable. It behaves like a constant speed prop, however, keeping the engine RPM within the power band at all speeds from 0 to over 130 MPH at full throttle. With this prop, I could cruise at 105 MPH, and I still had the same rate of climb as before. I no longer had to worry about throttle management during aerobatics; it simply wouldn't overspeed until I got near the 150 MPH redline. Hammerheads were much nicer because the engine was still pulling strongly (and much more smoothly) at the top.

The prop eliminated the mixture problems, giving nearly constant EGT's throughout the rev range. It also smoothed out the engine, and some balancers from Colorado Ultralight helped even more. As I flew it, I continued to tinker with it, finding small improvements here and there. By the time I first competed in it, it was flying about as well as I could make it fly, and I was quite pleased with it.

I did have a number of mechanical problems with it. It certainly requires more attention than the average Lycoming-powered airplane. Spark plug changes are needed at 25 hours (but they only cost $1.29 each), and in general more maintenance is needed, but the parts are cheaper. In the long run, I think the cost of operation is probably fairly close to that of a small Lycoming, the major cost difference being in the purchase price of the engine. Of course, the lighter weight of the Rotax allows a much lighter airframe, which in turn allows dramatically better climb performance.

My airplane easily outperformed most other light airplanes in climb. It would walk away from a similarly-powered Kitfox, and simply left a 65 HP Piper Cub in its dust. When I practiced aerobatics over the airfield, I could be at practice altitude just over two minutes after starting the takeoff roll. It is considerably higher performance in climb than a Decathlon. Only very high power-to-weight-ratio planes such as Pitts or RV-4's could outclimb it.

It also out-rolled a Decathlon, and is much more agile in other ways. However, its roll rate is inferior to most Pitts; I measured it at only about 90 degrees per second. Snap rolls are much faster. I found it fun to roll, but it does not roll effortlessly on a point like a Pitts. My plane was fairly easy to keep the nose on a point when rolling to the right, using only a little rudder and elevator. But nothing I did would prevent it from barreling a little and coming out slightly yawed to the left when rolling left. As a result, I almost always rolled to the right at contests.

Similarly, although there is almost no gyroscopic effect from the very light (7 pound.) propeller, judicious rudder work is required to keep it in line through a loop. Keeping feet on the floor results in a kind of corkscrew loop, yawed at the top but straight on heading again at the bottom.

These characteristics make the plane more difficult to fly in contests than a Pitts, I believe. When I flew the Pitts S-2B with Mike Goulian, I was stunned at how much easier it was to roll the Pitts than what I was used to. Looping maneuvers were much easier too. The Pitts seemed to work with me, requiring only very small, precise, light control movements to do exactly what I wanted it to do.

Like a Decathlon, the S-10 makes the pilot work harder to fly each maneuver correctly. If you ever see anyone win a trophy at a contest in an S-10, you know the pilot is good! On the plus side, altitude loss was never a problem, at least in Sportsman. In fact, I could fly the entire 1993 Sportsman sequence and end up higher than I started!

I could also fly the Intermediate sequences, although I never competed in that category. I think the plane could be competitive in Intermediate with a skilled enough pilot.

If you don't count your build time, or buy one already built, the S-10 is considerably cheaper to acquire and operate than a Decathlon or a factory built Pitts. However, I don't think it's very much cheaper to buy or operate than a Pitts S-1C.

In summary, it's a fun little plane. It's a lot easier to build than a Pitts (or a One Design, I'm sure) and less expensive than most. If building your own aerobatic plane is your goal, and you want to do it cheaply, the S-10 is a good choice. But it ain't no Pitts!

* * *

There were many times during the life of my little plane that I marveled at my good fortune. These times might happen when I was cruising down to Plum Island to visit my ultralight friends, the little engine humming smoothly, taking in the lush green fields from 2000 feet. Or racing the sunset across Connecticut at 7500 feet to be home by dark, southern New England spread out below me in a majestic panorama, fluffy white cumulus scattered between me and the earth. Or standing on the ramp at one of many small airports around New England, seeing the delight in peoples' faces as they shared my joy in my airplane. Or descending into Hampton Airfield after an aerobatic practice session, the white Hampton water tower turned golden in the late afternoon sun.

Many times I contemplated the miracle of flying an airplane I had built with my own hands. I felt myself the luckiest person in the world.

No matter what happens, whether I rebuild the plane, or buy a Pitts, or even if I never fly again, I will always have the memory of those moments, when I was the luckiest person in the world.