A Labor of Love: An Engineer Builds a Helicopter

Adam Weaver builds the mother of all do-it-yourself projects: a full-size, working helicopter.

The completed Rotorway JetExec helicopter, which was years in the making.

The completed Rotorway JetExec helicopter, which was years in the making.

Design engineers, many confined to designing for the large corporations that employ them, take on projects of their own to satisfy a need to build. The urge to make something with our own hands is denied to us with the specialization of labor in the modern manufacturing world. Engineers are allowed to create their designs on a screen, but when it comes to creating the part or assembling it, that is left to the machinist, a model maker, the shop. It is conception without birth. The birth process is out of our hands.

Stripping engineers of the satisfaction of giving physical form to our creations leaves a void that we often must fulfill in our spare time. On the plus side, this gives us the freedom to choose projects for which we have an interest—whereas we may rarely have such a choice in the work we do for our employers. For the author, this is the occasional piece of furniture. For the more gifted, such as Adam Weaver, the project is a full-scale, flight worthy, single passenger helicopter.

This astonishingly complex project may have started with a deceptively simple looking kit—and Weaver thinking he had a leg up on ordinary hobbyists and hackers with his Masters in aeronautical and astronautical engineering (from Purdue University). How hard could it be to make a model from a kit? It had all the parts, right? And it came with a plan.

That is what engineering school gives us, a belief that we can assemble or fix anything—from Ikea furniture to the broken-down office copier. We have this pride. We have graduated from what is arguably one of the toughest of all curriculums. We are engineers.

Weaver was in for a rude awakening. The helicopter parts from the kit would follow him from college to his present position as director of
Rand Simulation. By his own admission, he had a lot to learn. Weaver knew nothing about avionics. He had never flown a fixed-wing aircraft, much less flown what is considered by many to be the most challenging of all aircraft
—a helicopter.

What follows is Adam Weaver’s story.

How It Started

Some people have a project car. Weekends and evenings are spent working Bondo and fiberglass to patch holes, cursing the frustrations of electrical work, then relishing the feeling that comes when the engine roars to life. My “project car” is actually a Rotorway JetExec helicopter. Same journey, same payoff, but I would need a different license to drive it. About a month before National Aviation Day (August 16), I found myself getting my airworthiness certificate for my home-built helicopter.

This project, unlike the rusty wreck on side of the road brought home on a trailer, came in kit form.

At the time, I was studying gas turbine engines at Purdue’s grad school. I was working at a local Irish pub. A friend and coworker was chatting with a regular patron about a helicopter project and I got sucked into the conversation. Though the patron had worked out the plans and purchased all the parts to assemble the craft, construction of the remaining parts and the assembly itself had proven to be too much for him. He asked if anyone at Purdue could be of assistance. We were all in. There was no hesitation.

Nothing like the picture. The beginning of the journey of building a helicopter starts with these parts.

Nothing like the picture. The beginning of the journey of building a helicopter starts with these parts.

Set a Target So You Can Miss It

We spent the next year working with our pub patron on the build, but his was a journey that was soon to end. He passed away that year. My friend and I purchased the parts and continued the work where we had started. Later, I was to become the sole owner of the parts. I moved from near Purdue to New Hampshire, taking the parts with me. It is now eight years later.

I can’t believe we thought it was going to take one year to complete the helicopter. I have learned that you set a target date so you can miss it. Again and again. Without fail, every task took longer than I thought it would. All the studying, trial and error took a lot of time. Plus, there was that day job.

There were so many things I didn’t know about building a helicopter. Filling in those gaps took the most time. When lives are at risk, you need to be confident in your own work, and that confidence comes only after doing, undoing, and doing again. In the end, hopefully you are undoing less than you’re doing.

The electrical was a prime example of learning by doing and undoing. I must have laid every wire in that helicopter at least three to four times.

First milestone: the engine and drivetrain are installed.

First milestone: the engine and drivetrain are installed.

Google Me Not

I realized quickly that almost everything I needed to know could not be Googled. Instead, I had to really learn. I had to get my head around a problem and come up with a solution. The answer was not online. To understand what an aircraft mechanic knows—like where to mount the antenna—cannot be Googled. I had to study antenna theory. To set up the avionics, I had to master wire looms. To change, adjust or fix body panels, I became an autobody expert.

I had to learn that nothing will be completely finished. Each time I thought I had completed a section, ready to check the box and move on, something would come up requiring me to tear it down and put it back together. For example, last winter after the helicopter had hovered successfully, I had to tear down the drivetrain for a minor fix.

Perhaps with my next helicopter, I’ll remember the backward steps and be able to reduce the number of iterations.

It Takes a Village

I am not the only one who has attempted to build their own helicopter. As Tobias Funke states in Arrested Development, there’s dozens of us. This small community had worked through the problems I was coming up against for the first time. Sometimes, it would take a phone call to brainstorm the solution. It is a community where people help each other. When I heard someone had suffered a fracture on their tail rotor, I designed an assembly and brought it to an engineer friend, who fabricated it. It was a safety-critical component, so I was happy to provide it to the community. Multiple people have implemented this fix.

The Heart of the Matter—the Engine

The engine that powers my helicopter is a Solar gas turbine from the ’70s. It is a military surplus engine originally intended as an APU (auxiliary power unit) to provide power to mobile military bases. The decommissioned engines are refurbished and have proven to be popular with the experimental aircraft community. A helicopter requires constant RPM throughout the entire flight, which makes the gas turbine engine an ideal power plant.

It was with the engine that my hobby in aviation was finally enhanced by my professional background. Having studied and worked with turbomachinery gave me much-needed insight into the physics of the turbine engine. When the engine wasn’t operating correctly, I was able to rely on my coursework to diagnose the problem. I knew how to prevent compressor surge during acceleration, for instance. And my controls engineering courses helped me tune the electronic governor system to regulate the fuel control and design the circuitry for the engine and gearbox instrumentation.

Finding Experience

But theory and brute force wasn’t enough to make my helicopter fly. I needed wisdom and experience.  Not having either, I had to look for them in someone else. In 2019, I packed up the bits and pieces of the helicopter and went to Missouri to work with Orville Neisingh, recognized as one of the foremost experts in helicopter building  — and certain to be on the short list of important Orvilles in American aviation history. I was nervous as I opened the door of the trailer to show him how far I had gotten. I was a newbie and here was an expert. What would he think of me spending six years building a helicopter? Would he think it was a mess and want to tear it all apart? And if so, would it work when we put it back together? How much time would the teardown/rebuild take? I expected he would find many things I had done wrong. But instead, he began sharing many of the tips and tricks he had learned over his career. We went through the whole project in detail. I learned more about aircraft building in a few days than I had in the last few years.

After a thorough check of everything in the engine bay, cockpit and tail, it was time to mount the blades for the first time and do the precise work of static and dynamic balancing. Here, my academic background was of great help and I was able to balance an articulating rotor system.

How to mount helicopter blades in 15 seconds. Orville Neisingh, helicopter building veteran, points out the intended direction of  flight. 

Unsteady pressure contours on the surface of the craft during level flight, as simulated by Ansys CFX.

Theory was also put into play when doing the simulation. I used Ansys CFX to model multiple simultaneously rotating bodies and to calculate the pressure contours on the helicopter surfaces, which was useful in determining lift and drag on the macro level and also to find the magnitude of aero-induced oscillations.

We Have Liftoff

Several times over the course of two days we had run the engine up to full RPM. My expert would test to see if it felt ready to take off, then would shake his head and say he needed to make an adjustment and shut it down. Then one time he said, “Yeah, feels good. Here we go.” And up we went. It lifted off the ground ever so gently. We moved out into the field to begin testing some gentle maneuvers.

Despite playing it over and over in my head for the last several years, I can’t fully describe the feeling of what it was like when my helicopter lifted off the ground for the very first time.

A year later, I was able to meet up with my expert in New Hampshire. I had completed my homework assignments over the past winter. We went over the helicopter again, and then we began my flight training. We started with hovering—which I had been warned was “hilariously hard.”

A near-ground hover makes both the pilot and the engine work harder than during any other part of a flight. Keeping a helicopter safely a few feet off the ground is an intense mental exercise requiring coordination of multiple inputs from feet and hands. You never feel like you’re stable or you’re coasting. By the end of a day of training, I was mentally exhausted. The training period for hovering alone is around 20 hours. I needed all of it before I transitioned to the next part of training—bringing it up to altitude.

Appropriately enough, National Aviation Day 2021 found me continuing the official test flight plan—the final step before official certification of the helicopter. It marked the completion of my training. I now had the freedom to fly.