TEAM / Ison Airbike

The Airbike was my first build and still one of my favorite little airplanes. The original build was completed and the plane first flown in the spring of 2002. Since then is has been flown on trips across Washington, Oregon and Texas.

When I bought the kit, Wayne Ison's company was still called TEAM. All of the Airbike lawsuit ruckus happened soon after and the company name was changed to Ison Aircraft. It was a shame what happened to Mr. Ison, his company and the Airbike design as a result of all of that.

After ten years, the Airbike is still generating interest with the homebuilding community even though new kits and plans have been off the market. There are other designs that like the Legal Eagle and the new JDT AeroMax that fill that niche and have their own strengths and character. Even so, there is something about the design of the Airbike that really sets it apart in the field of ultralight and light experimental aircraft. It's aggravating that the design rights are tied up and probably won't ever see the light of day again.

The Airbike was recovered and painted a few years back with a new "L-Bird" paint scheme. Now it is disassembled in the hangar waiting for another engine. I could put the Hirth back on after a refresh from sitting in storage, but I've gotten tired of managing and feeding two-strokes. The next engine will be a four-stroke. It will almost certainly reduce the climb performance, but should make the flying much more enjoyable.

Construction

I started construction on the Airbike in the spring of 2000. It was finished in the spring of 2002 after about 850 hours of work. Not the fastest Airbike completion, but it did eventually get done. I bought the Airbike kit as originally offered from Ison Aircraft. This included the wing kit, a welded fuselage and a several other sub-kits.

Modifications

I stuck to the plans and all modifications were very minor and none that were structural. The two items that I've changed the most are the rudder pedals and the tailwheel. By the end of the first summer, I was not thrilled with the stock tailwheel installation and replaced it with an Aviation Products four inch tailwheel unit. I liked it better, but it was heavy. I used compression springs instead of the pushrod for steering and it took all the sensitivity out of the steering. Later, when I re-covered the plane, I put the stock tailwheel back on to help reduce weight. When it goes back together again, I will probably modify the stock tailwheel to accept springs. That should be the best of both worlds.

The rudder pedals were modified slightly for comfort. I welded small tabs on the sides of the toe pegs to keep my feet from sliding off. This lets me relax my legs a bit and not have to hold them up so much. I also welded a heel piece in the hoop that provides more area for the heel of my foot. The thin hoop tended to dig into my heels on long flights and would get uncomfortable.

I used a 90 degree muffler configuration and hung it from the rudder pedal support tube. The first attempt used thin steel strap, that would crack and break after 10-20 hours. Later, I welded two tabs to the muffler that simplified the mounting considerably.

Configuration

I chose most of my configuration knowing that I would register the plane as an amateur build experimental. This allowed me to include two five gallon wing tanks and not worry about breaking the Part 103 regulations. I also bought the brakes, droop wing tips and wheel pants. When the plane was re-covered, the tips and wheelpants came off to reduce weight and there were no noticable performance differences.

The engine is a Hirth 2702 40 hp two stroke. The gear box is a 2.29:1 reduction spinning a 62 inch two-blade Powerfin prop. I installed a Grand Rapids EIS for all engine instrumentation and used standard 3 1/8 inch steam gauges for airspeed and altimeter. I run the EIS and radio off of a small battery installed behind the seat. There is also a simple wingtip strobe system from Kuntzelman that runs off the engine lighting coil. I did not install a starter or a charging system for the battery.

If I remember correctly, the original empty weight was about 345 pounds. After the re-cover and weight reduction program, the empty weight dropped 30 pounds. I believe the empty weight is right around 315 now, but I haven't looked at the paperwork since it was pulled apart for storage. Gross weight is 560 pounds as specified in the original flight manual that came with the kit. Current usable weight should be about 245 pounds. With 60 pounds for full fuel, that leaves 185 pounds for pilot and gear. I weigh 160 pounds, so I have a little bit of leeway to haul some extra oil and a couple tools. Back when the plane weighed more, I weighed about ten pounds less, so it still worked without going over gross.

• Empty Weight 315 lbs
• Gross Weight 560 lbs
• Usable Weight 245 lbs
• Fuel Capacity 10 gallons / 60 lbs
• Fuel Burn ~3 gal/hr at 60 mph
• Duration ~ 2.8 hours at 60 mph with half hour reserve
• Range ~ 170 statute miles with half hour reserve

To be fair, I don't think I have ever flown more than about two hours in any leg of a flight. I start getting antsy about fuel long before I get down to the last gallon and a half. I typically plan for burning one tank and switching to the second as I start approaching the next stop. This usually works out closer to one and a half hour legs or less. Flying legs longer than 100 miles is pretty ambitious and the Airbike isn't known for comfort. Depending on the wind, you can easily fly two hours and not get anywhere near 120 miles. Much like flying a kite for two hours won't get you anywhere near 120 miles.

There are two good cruise speeds in my plane. Sixty miles an hour works well for going somewhere (slowly). If I'm just staying local, 45 mph is a nice comfortable speed. The wind and engine noise is much less and you're still comfortably above the stall speed. The temps on the Hirth agree with these speeds as well.

For long trips, I have a motorcycle tank bag that I install behind the seat. You can see it in the in-flight photos from the Arlington trip. I could put up to fifty pounds back there and still stay inside the CG range, but more than 20-25 pounds puts the plane at or just over gross weight. I've never loaded up more than about fifteen pounds anyway and that fills up the bag with oil, tools and a change of shorts. I usually haul a five gallon gas can as well to make mixing easier. I don't leave any fuel in it while flying, so it is not much weight.

Cross-country trips in the Airbike are similar to long road trips on a motorcycle. You can't take much, you're not that comfortable and you're in the wind all day. If the conditions are nice it can be a lot of fun. When conditions get lousy, it can turn into work very fast. Beating a path into a strong headwind all day can really wipe me out. I've had a couple days where I spent over seven hours in the saddle. After days like that, it takes a week or so for my interest in flying the Airbike to resurface. Those long trips are mostly fun, but always rewarding. It's a great way to get out of the usual day-to-day mindset and escape the daily grind.

Performance

• Cruise 55-60 mph
• Stall < 30 mph
• Vne 80 mph
• Take off roll on pavement is a little over 100 feet. About 200 feet on grass.
• Landing roll is about 200 feet on pavement and around 100 feet on grass.