Building a Sonex: what it’s really like

As a young man growing up in Wisconsin, I was exposed to what was, at the time, the annual EAA convention in Oshkosh. Long before it became AirVenture, it was an aviation event of epic proportions that etched itself in my soul and led to the lifelong dream of building an airplane and flying it to Oshkosh for the show. On October 10, 2015, phase one of this dream came to fruition after 4 1/2 years of hard work and financial commitment to build a Sonex experimental aircraft.

When life permitted me to actually consider such a project, I began to research the choices. My wife would tell you I obsessed over the choices and she may well be right. If I was going to take this project on, I wanted to be certain I could finish it. But what to build?

My mission was simple – an airplane I could build and fly, which would seat two side by side and allow me to get my aviation fix, yet still be cross-country capable. I wanted an easy-to-build kit with a good completion rate, aluminum construction, and an affordable kit price. There were many choices, but narrowing it down was relatively easy.

Can I do this? An EAA workshop helped alleviate some concerns.

I attended an EAA Sport Air workshop to ensure I could actually perform the required skills, and left with the knowledge and confidence that I could do this. That workshop was well worth the investment of time and energy, and in the back of the workshop in the EAA museum was a Sonex under construction by the EAA staff.

I knew I wanted a simple kit that I could fly for under $40,000. I also knew that in spite of my lack of experience in conventional gear aircraft, I wanted to build a taildragger. My initial conversations were with Joe Norris of EAA, who was a valuable resource of information and insight. Ironically, Joe would figure prominently later as I prepared for my first flight. If I were to tell someone considering taking on such a project, it would be to choose the airplane that fits your intended mission. Mine was flying for fun, including local fly-ins, breakfast flights, and the occasional cross country flight.

Several years of searching at Oshkosh, in magazines and online, analyzing kits and completion rates, real world costs versus marketing hype, I kept going back to John Monnett’s Sonex kit. It looked like it fit my mission, it was popular and had several hundred completions, and was very affordable. Sonex also offered several models of aircraft, and the Sonex could be built from plans, as sub kits, or as a complete kit. Several engine options were available.

The option to build from plans was important to me. If the company went out of business during the project, it was possible to complete it from raw materials. The plans for the Sonex are also so detailed that I felt they were enough for me to successfully complete the build if no factory assistance was available. The kit uses pulled rivets and to me that was also a bonus – it was easier to work on without constant assistance that is required when bucking solid rivets.

Finally, the company had great technical support and a solid reputation with the homebuilt community. It didn’t hurt that a Monnett-designed Sonerai II was in the family garage as I grew up. I was familiar with his aircraft design.

Enjoy the process – you’ll be doing it for a few years.

In 2011, I finally reached a point where it became financially viable and I had time in my life to do this. With the support of my wife and son, I signed up for the builders workshop held at the factory in Oshkosh. The workshop was to introduce my wife and me to the company, the kit, and to allow us to get a feel for the construction methods required to build the project. (My wife is one-of-a-kind. We met and were married at an airport and are partners in everything we do)

Much like the EAA Sport Air workshop, the factory builders workshop was another boost in the “I can do this” mentality I would go back to time and time again in the next four years. We left with a small project completed, a set of plans purchased the final day of the workshop, and a tail sub kit on order.

And so it began. I set up a workshop in my basement to build the tail sub kit and, by fall of 2011, I had a completed horizontal stabilizer and vertical stabilizer, plus control surfaces. The sub kit was very complete: I purchased tools and two sizes of clecos. I made small pieces, which assembled into larger pieces, which became an airplane tail. Pilot holes were drilled, pieces were cleco’d together, and then final holes were drilled. The parts were disassembled, all holes were deburred, rough edges were smoothed, and the parts were reassembled and riveted together. Repetitive, but not difficult. In fact, it was fun!

Pulled rivets require only one person for final assembly, so even though my wife was an invaluable building partner, I was able to work alone for much of the project. The experience made me confident we could build the remainder of the kit, so we ordered wings and moved the project to the garage.

The wings were more complex than the tail, and I spent a good five months over-analyzing this part of the project as it sat on a large flat table in the family garage. I was so concerned about building wings with a twist or warp that I couldn’t get started beyond the initial assembly of the structure. For me, this was one of the low moments of the project.

There comes a point when you realize you will actually complete the airplane.

But I got past it. I began to work on it actively again and while it took me some time to get back into the project actively, I did. Homebuilders will tell you to work on the project every chance you get – every day if possible – my experience would reaffirm that.

I ended up putting the wing frame on sawhorses and using a laser level and shims to make sure it was straight. With some help I was able to get one wing completed and riveted together. As we completed it, I stood back in amazement and for the first time realized that, while it was a long path to completion, I would eventually complete and fly the airplane.

The second wing went much faster and we were then ready for the fuselage kit. One reason we had ordered sub kits was lack of storage space. When the fuselage kit arrived with one wing still under construction, our two car garage quickly became filled with airplane. A vertical storage rack allowed us to store one wing, and eventually both, off to one side of the garage.

The kit proved to be exactly as advertised: many holes were pilot drilled from the factory as part of the advanced CNC processes used in today’s kits. Matched hole construction meant many components fit together right out of the box. The parts were well executed, and the plans were easy to understand, extremely comprehensive, and are so well done that a build manual was not required. Anyone with a basic understanding of blueprints can read and understand the plans.

Next was the fuselage, built in two pieces and then brought together. By the time the fuselage was complete, our garage was simply out of room. It was time to get it on the landing gear and remove the work tables.

Finally complete!

With that major step complete, we purchased an AeroVee engine kit from Sonex. There are several engine options to power the airplane, but the AeroVee kit was the most affordable. Having not built an engine since high school some years before, I had my concerns. But my wife, who is definitely more mechanically inclined than I am, assembled much of the case and components. The result was a well-built, VW-based engine with dual ignition and a lot of aftermarket parts. It appears only the case and possibly the crank was actually a VW stock part. The engine kit is complete, well-executed, and thoroughly documented.

Once complete, we hung the engine on the airframe in December 2014. Wow. What a moment! My airplane had an engine! It was a pivotal moment in the project. Next up was finishing it, which included several very challenging components: the canopy and the cowling.

If I had been required to do these two parts first, I would never have completed the airplane. The canopy was challenging enough, but the cowling… Wow! Working with fiberglass made me realize that anyone who builds an entire airplane from it deserves accolades far beyond what they receive. Simply put, it is nasty work.

But we got through it and, in spite of making a serious mess and a small mistake that resulted in replacing the windshield, it was done. By late August 2015, it was apparent it was time to consider moving the airplane to an airport and for me to prepare for its first flight. I am certain many pilots have the skills to hop in a new airplane and safely fly it. I knew I had not flown much during the build process, had very little tailwheel time, and no Sonex experience.

The moment of truth – first flight.

As a result, I went and got transition training… twice. One of those was from Joe Norris, now the flight instructor at Sonex Aircraft, and in charge of their T-Flight transition training program. The result was that on October 10, 2015, my first flight was uneventful and a delight. The airplane performed flawlessly, and that flight was the reward for literally years of dreaming about it and all the sweat equity I had invested in the project.

If you are thinking about building an airplane, I would say go for it! Do your homework, define your mission, and get the commitment of family and friends you will most certainly need to see it through. If I can build an airplane, so can you!

• Author
• Recent Posts

Robbie Culver

Robbie Culver is an instrument rated private pilot, flying under sport pilot privileges. He has made more than 3,000 skydives (many with multiple cameras on his helmet) and has over 1,600 hours PIC in single engine aircraft. He has owned a 1966 Cessna 150F, a 1973 Piper Cherokee 140, and is the builder and pilot of Sonex 1517. An active participant in aviation since 1984, he and his wife Brenda live in Frankston, Texas at Aero Estates Airpark (T25) with their two rescue dogs and a 1945 Aeronca Champ.

Latest posts by Robbie Culver (see all)

• Friday Photo: Texas Skies on a Fun Fuel Run - November 1, 2024
• A fun fuel run - August 21, 2024
• The friends I do not know - October 30, 2023