Proven Design; Ison Aircraft’s Eros

CONTROL QUADRANT – Throttle and choke are mounted on a forward quadrant with friction lock, while trim is positioned to the aft. The black shape (near fuel line) is the instep used to enter Eros.

PLENTY BIG – The Eros has all the tail it needs as discovered in steep turn exercises and general coordination maneuvers. Directly in line with prop blast, the horizontal is so effective, I never used the installed trim (though you might on a longer flight).

PANEL SPACE – Davy Lee Cooper’s Eros has all the instruments you could want without being crowded. However, Cooper mounted his radio on the side wall (see extreme lower right).

HEEL BRAKES – Davy Lee Cooper fitted his award-winning Eros with heel brakes. A solid plywood floor gives good support during entry and exit.

HAPPY BUILDER – Cooper poses with his Grand Champion Eros. He seemed to truly enjoy building the Eros as much as Dan Johnson did flying it.

AIRFLOW – The Half VW-shaped engine cowling has a wonderful vent along the top and indeed, Cooper’s Eros ran cool. Even though an upright cylinder engine sits inside, the cowling lends a gutsy look to the Eros.

SWING-OVER CANOPY – The Eros uses a canopy that hinges over the pilot, giving a wide entry point. A summer version of this canopy can be substituted using a forward windscreen and similar wood frame.

BEAUTIFULLY FINISHED – The Eros is a wood design, making it easy enough for the average builder to construct, given designer Wayne Ison and staff’s reputation for assisting their customers. This one (N-1171H) took 2 years for builder/pilot Davy Lee Cooper to construct, including the gorgeous paint scheme.

The pretty blue Eros with bright yellow stars on it is no ordinary ultralight. On second thought, “ordinary” and “Eros” aren’t words that go together. Of those aircraft designed by Wayne Ison and his former TEAM team, this model is the hottest of the fleet. I believe I’ve flown all Ison designs that were put into manufacture and Eros is one of my favorites. (In truth, it’s a tossup between the Max-103, Air-Bike, and the Eros.)
The Legend of Davy Lee
For this month’s pilot report, I got the chance to fly a special Eros, a Grand Champion at Sun ‘n Fun ’98 in the Lightplane Class. It belongs to owner/builder/pilot Davy Lee Cooper and it represents my second review of an Eros.
Cooper’s Eros is Rotax 503-powered as was the earlier Eros I flew, but both are derived from the Eros-preceding V-MAX with a Half VW engine. Without a doubt the Rotax 503 is more energetic, yielding better climb rates and somewhat faster speeds. On the downside it has a higher fuel consumption and higher cost.
Cooper addressed the Rotax powerplant’s higher cost by obtaining a used 46-hp single-carb Rotax 503 from a Hiperlight that had been retired. He got a great deal paying only $1,700 for an engine with less than 10 hours on it. Normally a Rotax 503 SC with a B redrive would run around $3,500.
The other noticeable difference is the full enclosure Cooper built. The first Eros I flew used a flip-over canopy arrangement but I sat behind a windscreen and was not fully enclosed. While I always value a new experience, Florida’s steamy heat made the fully enclosed canopy less enticing. I was uncomfortably hot in Cooper’s Eros. Beyond the full enclosure, it lacked any cooling vents. My only savior was the presence of small cutouts on either side of the cockpit, about at my elbow. These openings in the wing root let you visually check fuel. Cooper told me I could stick my hands inside the cutouts and cool my palms. I was glad for that but it wasn’t enough.
Not only did Cooper get a good deal on his engine, his Eros is living proof that you don’t have to spend a lot of money to enjoy ultralight flight and ownership. Cooper completely scratch-built this Eros, starting from plans and including sourcing all the components. The only parts he didn’t build were the wheel pants and the spinner, which he bought.

The star-covered Eros represents a $6,500 investment including engine, airframe, paint, and instruments, leaving out only a lot of labor and love. I can almost hear you thinking that to have an ultralight that cost so little, the labor hours must have gone off the scale. In fact, Cooper spent about 2 years building his award-winner. He didn’t count hours, but 2 years isn’t an unreasonable commitment to most builders. Of that time the last 3 months were spent deliberating on and executing the fancy paint job.
Even if Cooper had bought a kit, he’d have spent around $10,000, still quite a bargain and one that shows why wood aircraft like the miniMAX and this Eros can maintain consumer interest even in an age of fiberglass and carbon aircraft.
Cooper found many bargains. For example, the seat, which weighs nearly nothing, was made from Home Depot aluminum tubing and a RANS padded seat, which Cooper got as a hand-me-down from another builder.
Though it has a Rotax 503 hiding under the hood, Cooper’s cowling is shaped to accommodate a VW engine. The Rotax 503 does not require such a form but the cowl lends sharp lines to the plane, in my eyes. Cooper chose the 503 over the VW because of its better power-to-weight ratio; the Half VW is heavier and has about 10 horses less.
Being a major advocate of very light aircraft, I certainly admire Cooper’s effort to keep his Eros light. Nearly all experts agree that, in the realm of light and slower aircraft, the lighter an aircraft is, the better it flies.
For my money, a single seat is also enough. One of my favorite sayings goes like this: Genuine sport aircraft have one seat.* A 2-seater’s purpose may be commendable – giving instruction, taking along a companion, or helping a nonpilot experience the thrill of flight. But for pure sport flying fun, I believe a single seat is best and lighter is better.
* Single-seat sport aircraft include many ultralights (38% of ultralights sold, according to a survey by Ultralight Flying!), and nearly all hang gliders, paragliders, powered paragliders, sailplane gliders, aircraft flown aerobatically, plus most skydiving.

The Rest of the Story
Cooper’s story of creating an Eros from Ison Aircraft plans is only one visible element from the work done by ultralight legend Wayne Ison.
Ison’s TEAM Aircraft company from Manchester, Tennessee, achieved recognition and success by making inexpensive aircraft based on wood construction. With steady support from Skip Little, Larry Israel and others, Ison has been at it for two decades. During that time, his designs sold thousands of plan sets and more than 1,000 kits, an overwhelming majority of which are completed and flying. TEAM was one of the most-respected companies in light aviation.
In an unfortunate turn of events, a Florida pilot who crashed his TEAM aircraft sued TEAM. In a long story any American can understand, that pilot ended up owning the name and rights to TEAM. Ison refused to spend thousands fighting an aggressive lawyer and let his old company name go. Now, Wayne’s company is named Ison Aircraft and his legion of supporters celebrates his return along with anyone seeking a truly inexpensive aircraft.
Prior to Eros, Ison was inspired by then TEAM president Scott Severen to introduce the Air-Bike. TEAM followed this launch with a Tandem Air-Bike for training or recreational flying for two. Despite the success of the Air-Bike models, Ison also observed the interest of other pilot groups. Hence, Eros.
Ison is now “looking at his 80th birthday,” says long-time associate Skip Little (himself a chipper 69). In May 2003, Ison wrote a note to the company’s e-mail list asking if any of their customers are interested in investing in Ison Aircraft. This inquiry isn’t about selling out to the first person with some cash, says Little. Instead it’s about carrying on with the tradition and Ison’s fleet of miniMAX and other aircraft. New ideas haven’t stopped flowing – just look at the nosewheeled Air-Bike that Ison Aircraft showed to airshow visitors this spring. But when a right candidate comes along, Wayne and company want to talk.
Whoever ends up running Ison Aircraft in the future, ultralight pilots with some hours in their logbooks might be intrigued with Eros today. Here’s a sleek, relatively speedy, conventional-handling aircraft you can build and fly for $10,000 or even less. At that price, you should sit up and pay attention.

Four to Two
Careful readers of Ultralight Flying! magazine, or those who have followed Ison designsmay know that the Eros is really the older V-MAX revisited, this time with 2-cycle power rather than a Half VW engine. Using the Rotax 503 single- or dual-carb engine brings lighter weights than the Half VW engine.
In transition from the older V-MAX, Ison gave the Eros a sleeker exterior finish from the gutsy-looking engine cowl to a full-height turtle deck (curved surface aft of the pilot), plus wing tips, wheel fairings, and a prop spinner.
At the time Eros was offered, Scott Severen was TEAM’s president. He believed the 2-stroke powerplant made the design a much more marketable product. He was right, depending on the community of pilots being sold.
Many pilots outside the ultralight community are skeptical of 2-stroke powerplants based on perceived low reliability. But 2-strokes maintained correctly can give years of reliable service, albeit with different overhaul schedules and costs. The problem with 2-strokes isn’t the engine so much as the way they’re maintained (or perhaps more correctly, not maintained).
The two key strengths of a 2-stroke powerplant are – as most ultralight pilots know – the lower weight and robust power available. This explains why the Eros is hotter than the V-MAX.
Since it was designed with the heavier Half VW in mind, V-MAX has a beefed-up airframe. It’s similar to all those miniMAXes or other TEAM/Ison designs, but has more wood in strategic places. This stout frame made adding the potent Rotax 503 a reasonable choice.

As noted, Ison Aircraft offers two canopy variations, one for warm-weather flying and another full enclosure which could be quickly swapped if the temperatures dropped. The windscreen-only version provides more-than-adequate wind protection with a nice sensation of openness on warm summer days. This half-canopy setup is borrowed from the company’s successful MAX 103 model.
Full canopy or windscreen only, the entire construction neatly swings open to the aircraft’s right side, allowing a larger opening for easier entry. Once swung back into position, the window latch mechanism is very secure. I had no concern about it opening inadvertently and it was easy to use.
Eros may be a bit challenging for older, less flexible pilots to enter, although experience shows that such pilots can find a routine that works for them. Ison Aircraft supplies a foothold instep to help you up and into position. Then you stand on the seat frame and work your way down inside the adequately roomy cockpit.
Cooper spun the prop to fire up the Rotax for me; to save weight he did not fit either electric or pull starting. Hand-propping is distasteful to folks like me who earn their living with their fingers but I was happy to see how easily Cooper accomplished it.
An interior fuel gauge system is very simple in keeping with the overall design. Cooper cut “windows” in each cockpit sidewall so he could physically view fuel in the translucent tanks. It was easy to use. In addition, both fuel caps were within peripheral vision making it nearly automatic to check against cap loss. (For those who don’t know, air passing over an uncapped tank can completely drain the tank in a short time.)
An instrument panel, while small, had all the essential gauges needed in a sport aircraft. Cooper had a hand-held radio located on the right wall of the cockpit. With a headset, modern hand-held radios are more than sufficient.
Cooper mounted the throttle in a quadrant-style box and he also thoughtfully fitted the throttle with a friction lock that worked well. A primer was located on the instrument panel. Just aft of the throttle quadrant was the trim wheel, beautifully made of wood.

My earlier Eros flight was behind the “summer” canopy that gave massive visibility. Since the screen was only 3 inches in front of my head, it deflected the windblast effectively, yet it provided lots of circulation enjoyable for flying in Florida’s warm breezes. Before the end of this flight, I wished dearly for the summer canopy instead of Cooper’s fully enclosed version. Yet the full enclosure will find its advocates and it would surely be welcome on longer flights at cooler altitudes.
Eros is Enough
Taxi visibility in Eros is blocked directly in front of you but since she’s a single-seater, a small degree of tail wagging allows forward vision.
Applying full power at the end of South Lakeland’s 4,000-foot turf runway, I found acceleration with the Rotax 503 to be quite brisk. In barely over 100 feet, Eros and I were leaving the ground and headed skyward at a steep angle.
Visibility was superb forward of the wings, which are mounted at shoulder level, as well as upward in all directions, and even somewhat to the rear.
After a period of checking flight controls and characteristics – including my favorite series of Dutch roll coordination exercises – I came in for a few touch and goes.
Following Cooper’s advice, I used 55 to 60 mph as an approach speed. This yielded plenty of gliding capability from the smoothly cowled Eros. Historically, the popular miniMAX design has not had strong gliding capability, but the smoother finish of the Eros model improved this characteristic.

While still flying over South Lakeland’s many surrounding fields, I’d checked the descent rate so as to be informed on my first landing approach. At idle thrust and at 55 to 60 mph where I judged sink rate to be the best, I measured a power-off descent at less than 500 fpm. With the engine stopped and propeller disk drag reduced, sink would be even lower. At 500-fpm sink rate (with prop turning), the Eros is competitive with most ultralights and less than some. Eros’ wing area is larger than a miniMAX but weight is slightly higher so better glide performance must relate to lower drag.
Overall on my touch and goes, I found only one negative: The rudder pedals are so responsive that you could enter a ground loop more easily than if the pedals gave more feedback. Usually, responsiveness is a plus in my mind. A builder can rig the pedals to suit his or her preferences.
Cooper had installed heel brakes and while they worked as well as any ultralight mechanical brake system, I feel heel brakes are more challenging to apply with the precise amount of force desired. Toe brakes give a better feel but they are more complex to engineer and build.
Delightful Control
Ison’s miniMAX line of single-place ultralights shows fine control characteristics and Cooper’s Eros was no different. She proved to be a delight to fly, handling easily and responsively.
TEAM’s V-MAX with the Half VW engine was also pleasant to fly and 4-stroke buffs may still prefer it. But the majority of pilots will be more impressed with the performance capabilities of a 2-stroke Rotax-powered Eros.
While familiarizing myself with Cooper’s award-winning Eros, I found a sweet spot. At about 5,200 rpm the Rotax 503 produced a trimmed flight condition yielding 75 mph of cruise speed. At this setting – a medium range for Rotax powerplants – I discovered a low amount of engine-induced vibration and noise plus a good range for economizing fuel usage (though still not as good as the Half VW).

When the engine is set at full throttle, speeds can run near 100 mph while the factory lists maximum speed at 110 mph. These aren’t ultralight-permissible numbers, but this too-heavy Eros must have FAA registration. With N-numbers and a pilot’s certificate in your pocket, the Eros can use the quicker speeds.
Cooper’s Eros proved to be rather pitch-responsive to throttle movements. For example, when I increased throttle, the Eros nosed up measurably. This may have been exaggerated by my ignoring the trim but is certainly in the right direction. The Eros was so easily handled in pitch movements that I never used the trim wheel. On a longer trip, trim would surely be of value. Thanks to light control pressures and adequate authority, gripping the joystick with a couple of fingers could fly the Eros.
Rudder pedals had the same light response while airborne as while taxiing. Given that the ailerons were medium-light in feel and the rudder lighter, the Eros did not have perfectly harmonized controls, although this is a modest criticism of Eros flight handling.
With stick forces quite light, my Dutch rolls (coordination exercise) characteristically went very well, even to steep angles. As with most aircraft, coordinating the controls will take a little practice to become very fluid. But being able to perform steep Dutch rolls right from the start has become a measure on which I can depend.
Perhaps you won’t be surprised to hear that my steep turns also went very well to a high bank angle. At no time did I notice any tendency to run out of stick range. Clearly the tail feathers of the Eros design are well suited to greater power and weight.
At idle thrust, the Eros wanted to drop its nose (again, the right direction), but the trim wheel Cooper installed could control this. Other builders might just set the trim for their weight.  Fortunately, pitch author
ity is enough that you always have control if you have the joystick in hand.

Since Cooper’s Eros was swift and glided well, compared to all ultralights and to other miniMAX models, I expected to have longer landing approaches and roll-outs. In fact, I was able to set her down comfortably in perhaps 200 feet of ground roll-out. Controlling approaches was done by slipping – which the Eros does well – or merely by approaching slower.
Loving Eros
Eros is defined as the god of love in Greek mythology. My computer dictionary also defines Eros as creative, and I’d say these references fit the enjoyment I gained from flying the machine. Designer Wayne Ison and his loyal staff were creative in their application of skill to the airplane.
Next comes the effort of builders like Davy Lee Cooper who clearly did great justice to this interesting design – and without spending a pile of money.
While you’ll invest some 400 hours of build time to include finish work, this effort is roughly average among ultralight construction kits. Many customers have told me that Ison and his team provide superior support and generous advice. In addition, with so many Ison designs in the field, you can probably find someone local to give you a few tips.
You simply must look at this: The price for the Eros kit is a modest $4,395. You can buy a brand-new Rotax 503 engine for about $3,500. Adding paint cost and a few instruments, you could get airborne for $9,000 to $10,000. For less than $12,500 you could have electric starting, differential brakes, and even accessories like an emergency ballistic parachute. Put it all together and this becomes one dandy sport aircraft for a very affordable price.
For those willing to invest a bit more effort – sourcing materials and fabricating parts as Cooper did – an Eros could provide delightful ultralight-type flying on a lean budget. Let me leave you with this thought: An Eros at about $10,000 is half the average price of a new car. Which is likely to deliver more fun?