Technicalities: What Worked and What Didn’t

After 14 years of flying my second homebuilt, preceded by nine years in my first, I wish I could say that most things that can go wrong already have, but the gods might think me insolent. By now, however, I can at least say with some confidence what has worked and what has not.

My first project, Melmoth, which was destroyed on the ground, as I sat in it, by an errant Cessna in 1982, had several features that were unusual at the time. They included downdraft cooling with a single intake below the spinner, wing-mounted airbrakes, automatic fuel-tank switching, a double-slotted Fowler flap, a T-tail with a stabilator and ailerons whose incidence could be adjusted in flight. The landing gear was retractable, of course. The association of speed with retractable gear was inescapable then, and the new breed of fast fixed-gear airplanes with powerful turbocharged engines undreamed of.

The official raison d’être of the Experimental amateur-built category is “education and recreation.” I got both. In the course of making retractable oleo-pneumatic gear from scratch, I learned random facts about O-rings, dissimilar metal bearings, heat treating, centerless grinding, heliarc welding and the effect of foaming on the damping properties of hydraulic oil. I added to my mental thesaurus phrases such as “hydrogen embrittlement” and “hard chrome plate and bake” that I could toss off to bolster my engineering cred.

As a homebuilder, however, I carried no hull insurance, donated my labor and found the gratification of a smoothly functioning retractable gear — which it was, most of the time — well worth the trouble of building and caring for it. I had a few mishaps — most notably an untimely genuflection of the right main on the ground at, of all places, the Bede factory in Newton, Kansas — but I never repented the choice.

The adjustable-incidence ailerons, however, proved to be a pretty useless feature. Melmoth’s airbrakes consisted of a rectangular slab of aluminum honeycomb that rotated out of a vertical slot in each wing. Driven by the same ancient Air Force-surplus hydraulic pump as the gear and flaps — once you have a hydraulic pump, you might as well use it for everything — these popped up rather abruptly, killing some lift in the process and giving passengers an unexpected, and I suspect undesired, thrill. They were good for getting down fast, but not much else. On my second airplane, a four-seater that I imaginatively named Melmoth 2, I tried a different approach: a flat surface of about 3 square feet that swings down out of the belly, like the airbrakes of World War II dive bombers. Air pressure ahead of it lifts the nose, helping to slow the airplane. At approach speed it helps trim out the flap, and presumably even adds a little lift.

Melmoth had a double-slotted Fowler flap that deflected 45 degrees; Melmoth 2 has a single-slotted one that deflects 30 degrees. Both travel aft all the way to the trailing edge, increasing the wing area, before tilting down to their full deflection and are very effective. My homemade hydraulic cylinders, however, have been a constant source of minor leaks and an occasional crimson tide. Sometimes I think I should have used clean, dry electric actuators; but then I remind myself that all untried systems are trouble-free.

Melmoth’s control stick was between the pilot’s knees. Melmoth 2 has a sidestick, which provides much less leverage. After flying for several years with rather high roll forces, I made a second set of ailerons with more aerodynamic balance. They are better, though still not so light as I would like. I also initially had the elevator trim tabs doubling as servo tabs to lighten pitch forces. This proved unnecessary and left me with limited trim authority. I eventually ditched the servo component and never missed it.

Very long range was a design goal of both Melmoths; the first held 155 gallons of fuel, the second 140. But the second, because of superior aerodynamic efficiency, has about the same 3,000-mile range as the first. Keeping accurate track of fuel quantity is hard when the fillers are at the wingtips and you never fill your tanks. In both airplanes I relied on a totalizer; in Melmoth 2, whose wings are entirely wet from root to tip, I added small fuel-tight ports at the wing roots to allow dip-sticking the fuel from time to time to reset it. Unbreakable transparent standpipes in the cockpit sidewalls would be better still.

Despite being bigger, Melmoth 2, which has the same 200 hp Continental engine as its predecessor, is slightly faster, cruising at 170 knots on a 60 percent-power fuel flow of 8½ gallons an hour. It also climbs better. The principal reason for both improvements is wingspan. Melmoth started life with a 23-foot span and an area of 92 square feet. After adding a turbocharger in 1980 — a change that many people said would be troublesome, but wasn’t — I increased the span to 28 feet and the area to 112, discarding my beloved cambered and beavertailed tip tanks. Melmoth 2 has a 106-square-foot wing of 37-foot span. When it comes to range and climb rate, span is magic; for roll rate, not so much. Area, on the other hand, is overrated.

On Melmoth 2 I kept the T-tail, which I liked, but replaced the stabilator with a fixed stabilizer because of some memorably unpleasant minutes when ice accumulation on the leading edge of the all-flying tail made it, and the rest of the airplane, bob up and down ominously.

Both Melmoths are roofless, with canopies almost completely transparent. Entry and exit have been challenging in both, but Melmoth 2 particularly because it is even more difficult to get into the rear seats, which face aft, than the front ones. I have perfected my own entry technique, however, and find that most passengers are too polite, or too anxious, or too busy grunting to complain.

I once took a blind girl flying. She sat in the back with her mother, whom I could hear narrating the sights to her through the intercom. Most of the flight was over open ocean. What terrors did she feel, I wonder, imprisoned in that all-but-inaccessible rear seat?

Perhaps the next Melmoth should have club seating.