By Mark Pensenstadler, EAA 9030636

This piece originally ran in the April 2026 issue of EAA Sport Aviation magazine.

My newest creation is a Zenith CH 750 Super Duty that I’ve affectionately named the ACME Bomber. Looking at the self-designed and -built cargo bomb on the bottom of the airplane, one can see where the name ACME Bomber might come from. I even designed and created nose art for the right side of the cowl that had to include my favorite Looney Tunes character Wile E. Coyote.

This is my fourth homebuilt I’ve completed and my second from a Zenith Aircraft kit. In 2020 I completed the Blue Angels Cruzer (see the November 2020 issue of EAA Sport Aviation) and enjoyed the project so much that I wanted to build another one. This time, however, I’d go for the larger three-seat CH 750 Super Duty.

This airplane belongs to the fictional 750th Aerial Surveillance Squadron, better known as the Flying Donkeys. In my case, building airplanes is more than just riveting parts together to create a flying machine. I derive a lot of fun and enjoyment in creating an entire theme around the airplane — even if it’s a fictional story like the number of bombing missions this airplane has flown (as seen by the art on the left side of the cowl). There is direct evidence that this airplane has seen combat — if you look closely, you may see some bullet holes in the fuselage. And don’t tell anyone, but I already have a theme in mind for my fifth project!

The ACME Bomber is built from a standard kit with only a few modifications. I added two small cargo compartments to the rear bulkhead, hardpoints for cameras on both wings and the vertical and horizontal tail, and many custom-made fiberglass fairings to clean up the airframe and give it a professional “finished’ look. Oh, and of course the “cargo bomb” on the bottom. I know modifications add time (and usually money), but it’s a part of aircraft building that I really enjoy. The Super Duty has plenty of cargo room behind the two pilot seats, so I didn’t really need any additional space, but early on in the project I knew I wanted to add a fake bomb to the bottom of the airplane. And why waste all that empty space? I might as well design it with a door so I can open it and add some cargo.

One of the best mods I made was to replace all of the plastic brake lines and all the Zenith supplied fuel and oil hoses with high-quality stainless braided Teflon hoses from Aircraft Specialty Flightlines (ASF). Each firewall-forward hose has an integral fire sleeve and is pressure tested, data tagged, and ready to install, so I didn’t have to add the bulky “old-school” fire sleeve. Unlike regular rubber hoses, which have a life of five to seven years, the stainless Teflon hoses have no defined max life and can be used as long as they are inspected and cared for. I value this because I will never need to drill out rivets in the wings to change standard rubber hoses. Steve, from ASF, was great to work with and very helpful in designing a fuel and oil system I have great confidence in.

The bomb is built almost entirely from 6061 T6 aluminum and solid 3/32-inch rivets. I made two 12-inch round bulkheads using the same exact method one would use to make wing ribs. Then I wrapped 0.016 aluminum around the bulkheads to make the body of the cargo bomb. There is a math formula for making the cone in the back, and then I just designed and cut out some fins to make the whole thing look like a bomb. I also had to scratchbuild a 12-inch fiberglass nose, and that was simple to do but time-consuming with the amount of filling and sanding required. In the end, it turned out just as I envisioned and provides the airplane a unique way of carrying some additional cargo.

The panel hosts dual Dynon HDX screens with an autopilot controlling pitch and roll. I am the first to install an autopilot in a Super Duty, so I had the pleasure of engineering the servo installations for the elevator and aileron servos. Also included is a Garmin 175 IFR GPS for occasional IFR flying. I’ve always been happy with the Dynon Avionics products because the information is presented well on the screens, the quality is outstanding, and the whole system is easy to install and wire. Even connecting the Garmin GPS to the Dynon system was a simple task with clear instructions from Dynon’s installation guide.

Power is provided by a Lycoming O-360 with two standard mags mated to a Sensenich ground-adjustable prop. The simple engine setup is exactly what I wanted for reliable backcountry excursions.

I painted every part on this airplane myself using AkzoNobel U-Tech U500 paint, which I was able to source locally. I started off with a temporary paint booth in my hangar made out of large tarps and then ended up building an 8-by-18-foot fully enclosed paint booth in my garage with inlet filters and an explosion-proof exhaust fan.

Painting the airplane green may not have been the best choice for visibility in the backcountry, but I’ve made up for that with lights. All are super high-quality lights from AeroLEDs and include a beacon on the bottom, nav/strobes, wig-wag lights on the leading edge slats, and a SunTail light on the trailing edge of the rudder that acts as a strobe or a solid white nav light. For the leading-edge wig-wag lights, I wired one switch so that in one position they both remain on for use in taxiing or landing. Move the switch one more step up and they wig-wag for high visibility in the pattern.

For those interested, I have documented every part of this build (including the cargo bomb) on my Kitplane Enthusiast YouTube channel, from receiving the crate and finishing construction to completing the first flight and test program. Filming the build process certainly increased the build time, but I’m hoping the education the build series offers to other builders is well worth the time and effort.

Now I’m looking forward to those backcountry excursions and camping trips!

Attention — Aircraft Builders and Restorers

We would love to share your story with your fellow EAA members in the pages of EAA Sport Aviation magazine, even if it’s a project that’s been completed for a while. Readers consistently rate the “What Our Members are Building/Restoring” section of the magazine as one of their favorites, so don’t miss the chance to show off your handiwork and inspire your peers to start or complete projects of their own. Learn more ->