Builder’s Corner – Marty Maisel and the Cavalier SA102.5 Project

I started flying shortly after I graduated from college, got married and got a job. As with many private pilots flying was a passion, but expensive, and it had to get in line behind family, mortgage, car payments, etc. In 1970, after working 10 years in the aviation industry (first Hamilton Standard (propellers) and then Boeing Helicopters (VTOL aircraft)) I moved to California when the opportunity arose to work at the NASA Ames Research Center for an Army aviation research organization.

While living in San Jose I initially flew out of Reid Hillview Airport, renting tail draggers from Amelia Reid. Hoping to reduce the cost of flying and accumulate more flight time, I bought a share in a Piper Cherokee 140 based at SJC. Things went well for a while — until I encountered some maintenance issues. I realized that this relatively large group of owners was not the perfect arrangement for a safe airplane – so I sold my share.

It was clear to me then that to fully control the maintenance of the aircraft, I would need to be the sole owner. But, oh yes, I remember now – I couldn’t afford to buy a flying certificated airplane. What to do? No problem – I’ll just build one. Good idea, yes?

It’s somewhat embarrassing to report that my bright idea to build an airplane happened in the late 1970s. At the time composite homebuilts were the latest rage (the “kit” revolution hadn’t occurred yet). Reports of builders having to give up their projects because of allergies to the epoxy adhesives scared me away from that material because of my history with allergies (the usual stuff). I had no welding experience and the sharp edges of aluminum sheets looked dangerous (I hate the sight of my blood) so I didn’t choose to build a metal project. With years of balsa model building behind me, I thought my natural choice would be a wood airplane. After all, it was good enough for the Wright brothers, wasn’t it?

I selected a conventional-looking (engine in the front, tail in the back) two-place design called the Cavalier SA-102.5. This aircraft was based on the Minicab which was developed shortly after WWII by French designer Yves Gardan. The Minicab structure was strengthened for higher power engines and the resulting higher speed and modernized with a swept-back rudder and tip tanks by Canadian Stan McLeod. I bought my plans from Stan (and, amazingly, we are still in touch). I’ve included a picture of a completed Cavalier, for members who may not be familiar with this aircraft.

Since this was my first airplane project, I spent some time researching material sources (including a visit to Flo Irwin at the start-up Aircraft Spruce when they were in Fullerton, CA) and studying wood adhesives. In the good tradition of an “engineer” I selected FPL-16A (a two-part epoxy adhesive developed by the Forest Products Laboratory, a research entity of the U.S. Department of Agriculture) based on available comparative stress/performance data. As with all epoxies I use protective gloves during gluing and, to date, I have not had any allergy problems from this product.

I finished the empennage and fuselage structure in the early 1980s. That was when the FAA GADO (General Aviation District Office) would send inspectors to the site where the airplane was being built. I got my tail surface structures signed off in my garage by the GADO inspector before skinning. (I figured, since I was an “aircraft builder”, that if the FAA goes to Boeing, they should come to my house as well). Later, the huge growth of homebuilt aircraft starts caused the FAA to abandon interim inspections, resulting in the EAA Tech Counselor program.

Well, I learned a few things about building an airplane since then – including “life gets in the way”. My work (as in how I got paid) involved lots of travel and lots of time away from home – not good for making progress on my project. While still involved with a busy work schedule and the usually family commitments, the Cavalier project became dormant for the better part of two decades.

But, there is always hope. I retired in 2002 and the dusty airplane parts came with me when I moved to Lincoln (my wife liked the house, I liked the three-car garage). After taking some time to get settled, I restarted my building effort.

The first big challenge in my resurrected project was the fabrication of the wing forward spar – a 24.5 ft one-piece box structure employing caps made of multiple laminations of spruce and plywood webs. The gluing of the laminates in one operation required a coordinated effort by several people. One of the great gifts that EAA Chapter members have is the wonderful assistance of fellow members. My spar was fabricated during several sessions with the skilled help of EAA friends and a neighbor. Another “truism” I learned at that time is “you can never have too many clamps”.
Cavalier forward spar, prior to application of web plywood

While working on “real” aircraft projects I learned that engineers never seem to be content with the current design. That’s why they have management who force the design to be “frozen” at some point. I don’t have anyone telling me to freeze the design, so I seem to continue to find things that “need” to be changed. Among the changes from the original drawings are: elevator and aileron push-pull tube activation instead of cables, electric pitch and roll trim tabs, flap torque tube linkage instead of cables, dual control sticks instead of a center stick with “Y” handles, slotted flaps instead of split flaps, “gull wing” cabin doors, a modified rudder control linkage, and provisions for mass balance weights on the ailerons. Another deviation from plans is the use of a tail wheel instead of the nose gear. This change was prompted by reports of several Cavalier nose gear problems (ranging from shimmy to structural failure), although many Cavalier owners feel their nose gear has performed very well. The main landing gear brackets, made of thick 4130 steel, were bent (with considerable effort) on Ken Ledwith’s heavy-duty bending break – thanks Ken.

A valuable benefit available to EAA members is the Technical Counselor program. Several Tech counselors from Chapter 526 inspected my airframe structure during the building process.

After the wing was built up behind the forward spar, I assembled the wing, stabilizer and elevator to the fuselage to align all components, drill mounting bolt holes, verify proper control range of motion and to detect and clear any control component/structure interferences.

“Fit-check” assembly. Does it look like an airplane yet?

The next task was “skinning” the wing. With all control, fuel and electrical components installed the partially skinned wing is shown below.

All plywood joints had to be “scarfed”, that is the intersecting skins are cut at a 12 to 1 slope (or better) to achieve a structurally adequate joint.

One of the unusual features of the Cavalier design is that all of the fuel is contained in wingtip tanks. I like not sharing the fuselage with a fuel tank. The fiberglass tip tanks are fabricated on a male mold in two main sections with internal bulkheads.

The next photo shows a partially completed tip tank. The upper and lower sections of the tank are joined at the overlapping horizontal seam. Fuel is contained between the first and fourth bulkhead seen as the vertical lines (dark due to the use of a different epoxy).


The interior of the tanks was coated with Jeffco 9700 fuel tank sealer to avoid deterioration of the epoxy in the event that fuel containing alcohol is used.

The completed tip tanks were supported in a frame attached to the wing tip to establish its proper orientation while the fairing connecting the tank to the wing was fabricated. It is estimated that the tip tanks will hold about 16 gallons of fuel, so that results in about 100 pounds hanging off the end of each wing.



Tip Tank Positioning Frame Tip Tank Fairing

After I moved the project to Lincoln airport the aircraft was covered with Dacron, using the Stewart System adhesive. I switched to Polyfiber products for UV protection and the base color coat.

I decided to use polycarbonate (Lexan) material for the windshield because of its shatter-resistance and ability to be cold-formed. The downside of polycarbonate windshields is that they are easily scratched. The windshield is not permanently installed yet but the next photo illustrates the windshield/fuselage contour.


The instrument panel is set up for primarily day, VFR operations (but I do have position lights and a strobe).


On the main panel, basic flight instruments are clustered on the left and the radio, transponder and circuit breakers are on the right. The lower center panel contains the fuel gauges (with the associated electrical fuel pump switches) and the engine CHT and EGT gauges.

I acquired a Lycoming O-290D2 engine from a fellow Cavalier builder in Minnesota. It had been recently overhauled and has a Lightspeed electronic ignition in place of the left mag. I will be using a 74” Sensenich propeller with a 57 pitch. That prop/engine combination has flown on several certificated aircraft.

That’s Jack Parks under the hood welding my engine mount.

After the engine was mounted I made a fiberglass cowl over a foam form applied around the engine. To my surprise the cowl turned out to be a labor-intensive task, but after many moons, I think I finally got it right. My philosophy is “don’t let the inanimate object win”.

Recent work has focused on firewall forward stuff – electrical, fuel lines, baffles. ducting, instrumentation, etc.

Here’s a general view of how the airplane is looking these days:


Well I may not be setting the record for the longest time to build an airplane, but I’ll bet I’m a competitor in that field.

I have been fortunate to have had the counsel, guidance and encouragement of a number of fellow builders at KLHM. Among them I owe a special thank you to Dick Rupe, Lee Graybill, Ken Ledwith and Jack Parks.

Years ago when I mentioned to someone that I was building an airplane, he asked: “Isn’t that a big job?” My answer was “No, it’s not a big job ……it’s an infinite amount of little jobs.” It’s also great fun.