This is from the July 1978 Sport Aviation.

John Chotia and the Weedhopper at Chino '78

The WEEDHOPPER is my 23rd ultra-light design. Over the last 12 years I have built 18 hang gliders of both rigid wing and flex-wing types; the other 5 were powered ultralights, some foot launched and others wheel launched. All of these planes went through several configuration changes, so all together over 50 aerodynamic concepts have been tried.

The goal has always been a low cost, fun, safe airplane. The pure hang gliders were certainly fun but lacked convenience and safety. I concluded that hang gliders are okay for young, single types with the time to chase the weather, but for me with 4 children and a wife, flying time is limited so I didn't want to spend it traveling and waiting for the wind. Foot launching lends itself to scrapes and bruises, too, and I was getting tired of that.

I tried foot launched powered hang gliders but I was near 200 lbs. so I still needed a hill and wind. This led me to a rolling launch and aircraft status. (It interesting to note that I've found the FAA much easier to work with than some of the very political hang gliding clubs which control flying sites!)

This slow reinvention of the airplane has allowed me to re-evaluate just how much structural complexity was necessary. The Weedhopper is the final result. I could have made it perhaps 15% lighter, but construction time would have been easily 10 times as great and the plane would have not been nearly as rugged. A 15% savings is only 24 lbs. anyway. I found it very easy to add pieces to achieve a particular function, but much more difficult to simplify while retaining all the functions I consider necessary for safe, convenient, fun flying.

The final design (Weedhopper) came down to the following:

1. It must be powered to be independent of wind and hills.
2. The wing structure must be rigid to retain stability, controllability and safety in all attitudes (even inverted).
3. There must be aerodynamic control of at least pitch and yaw; dihedral has proven adequate when combined with rudder for roll control when airborne.
4. The plane must be capable of lifting a "mature male", i.e., 220 lbs., at field elevations of at least 5000 ASL.
5. Wheels are needed to allow less-than-athletes (soft old men) to fly in safety.
6. Ground handling must be easy and convenient; to me this meant tricycle gear with a steerable nose wheel.
7. Since there are no ailerons, the landing gear must be very stable. The Weedhopper's main gear is 4' 4" wide and the pilot sits only 6" off the runway.
8. The structure must be simple, low-cost and rugged.
9. It must be easily portable and only require one man to set up.
10. Oh, yes, It must be attractive! Everyone has an ego to deal with!

Any smooth area is a runway for the Weedhopper

Earlier "short nose" version of the Weedhopper in flight

The Weedhopper meets these goals and then some. The tractor engine choice allows the empty plane to balance at the proper point to fly so the pilot's seat can be located directly on the C.G. Weight and balance tests with various pilots show about 1/2" max. contrast to most pusher-type ultra-lights which are very sensitive to pilot weight changes. This feature allows several people to fly the same plane without worrying about stability or trim. The central pilot forward engine arrangement is safer in the event of a crash since you don't have a screamin' 5000 rpm engine out back waiting to punch through the pilot's back and the pilot is protected at least a little by the surrounding structure. The central pilot position also lends a feeling of security because the pilot is more In the plane than perched on it; he has better attitude reference, too.

The wide, low landing gear handles crosswinds better than I hoped for. Take-offs and landings have been made in up to 10 mph winds 900 to the runway. Just keep the nose wheel down until take-off speed is reached and don't get caught halfway between rolling and flying. Landings have been made at crab angles approaching 45° (on grass) and the plane just plops down and straightens itself out.

The Weedhopper has been flown in moderate turbulence and handles it quite well, the only problem being low speed and high drag. This allows sudden gusts to sap your momentum so you need to use more power. Attitude control and auto-stability are very good and the rudder is as effective as ailerons in leveling the wings, if needed. Most often the pilot must correct pitch to avoid ballooning in gusts. Flying in gusty winds is not recommended, however, since at low altitudes the space needed to correct could be greater than the space available, especially during turns, but if the wind comes up during a flight, the best method to get down is a straight in, fast approach and fly it onto the runway. Also with a 30 mph cruise you might be surprised at how little headway you can make into a 25 mph wind; you could walk faster.

Stalls in straight flight and shallow banks aren't unusual except that only about 25-30 ft. is lost, power off and slightly less power on. With the small high speed propeller, torque isn't much of a factor. When stalled at moderate to steep banks, the inside wing drops. I've never allowed it to spin beyond V4 turn but the recovery is rapid and normal. The altitude lost in such a wing-drop-recover maneuver is about 50 ft., sometimes less.

The Weedhopper has flown with adequate performance with a 220 lb. load at 4500 ft. ASL on its single surfaced wing and direct drive 19 hp engine, but there are add on options, such as a double surfaced sail and streamlined struts which are recommended for pilots over 190 lbs. who plan to fly at altitudes over 4000 ft. These will be especially important on warmer days. I feel that a plane isn't fun to fly if the performance becomes marginal even once in a while.

I feel that the Weedhopper really opens a new area of recreational flying. It is low cost, yet still safe, functional and not under-powered or difficult to fly. Ultra Systems was incorporated early this year to promote and produce the Weedhopper. I had personally carried the cost and effort of development over the last 12 years with just the help of my wife and a few friends. Now Ultra Systems, Inc. has the capital and facility to do a proper job of marketing my dream. For me it is a dream come true, one I hope many other people can now share.

Further information is available from Ultra Systems, Inc.,P; O. Box 2253, Ogden, UT 84404.

Er ... "cockpit" details

Yamaha engine details

This information came from the March and April, 1958 issues of Sport Aviation.

Ray Stits designed a number of very successful airplanes in the 50's and 60's. The Skeeto was his experiment with what we now call an Ultralight. In its initial form, the Skeeto weighted in at 170 pounds. With a 3 hp engine, it would just maintain level flight if it was towed into the air behind a car. Ray went through a number of engine options, but was never able to find an acceptable installation. His final attempt, number 8, was an Evinrude outboard engine that put out about 18 hp with a direct drive.

Quoting from the article:
As a summary of the whole ultra-light project, my opinion is that any aircraft with a wing loading of 3 or 4 lbs. per sq. ft. is not practical. With a 10 mph wind blowing, it is necessary to "walk" the airplane out to the runway to play it safe. With a stalling speed of 18 or 20 mph, there isn't much of a margin between flying and landing when you have gusts of up to 15 mph, which is quite frequent in many parts of the country. As a novelty and a hobby, ultra-lights are a lot of fun but just not practical.

The following article is from the January 1964 issue of Sport Aviation. (I left out the builder’s name. By the grace of a benevolent God or just plain dumb luck, he may still be alive.)

Every project has to have a start, but in this case it isn't very clear when we started planning. Ronnie Streeter, a neighbor boy who likes to build things, and I had been cloud-nineing on the building of the simplest, easiest to build and cheapest airplane we could conjure up. The airplane was going to be a test bed for ideas.

We started to work on this crime late one night after sitting around the shop stove and talking. We were thinking that if we just had the ribs built we would have it made. All of a sudden, I remembered that dad had a set of old Piper J3 ribs overhead in the garage. We had the airplane half built, we thought! We built most of the wings in a week while designing the fuselage.

After putting aside many different ideas, we ended up with the common tractor arrangement. We thought a lot about sticking the pilot out in front and sticking the engine a little back of the CG, but this looked too wild.

We built the fuselage in one night, then spent a week finding a set of wheels and a way to tie the front of the fuselage together. The wheels were old bicycle wheels that would fit fairly snug on a 1 1/4 inch tube... no bearings, but lots of grease. Although there were no shocks, with the big wheels smoothing the ground and the slow landing speeds, they were not needed. Besides, do you know of a cheaper, lighter, easier to get and easier rolling wheel? The nose wheel was a tricycle wheel with the fork cut down.

At this time, it was evident that we had somehow placed the seat too far back, so it was just moved ahead and things left as they were. How we got the CG off so far was never explained, as we had taken a 12 foot plank and a saw-horse to get the measurements. Not having the seat back running down the landing gear made the fuselage much weaker.

To save work, a set of dad's old Pietenpol tail surfaces were put on, and taken right off as they were too heavy. We built a set one night which weighed 9 lbs. Again, the lightest, simplest and easiest to build that we could think of. A weight and balance was run with the saw-horse.

The wing was attached by drilling two holes through the fuselage and putting in bolts with short lengths of tubing welded to the head. With this attaching method, the angle of attack could be changed with washers and the CG changed by drilling new holes and moving the wing back and forth.

The wing, having 3/8 inch plywood spars, caused much talk. We knew they were big enough, as we had set the wing on saw-horses positioned at the root and strut fittings, then figuring a load of 2 1/4 G's, and static loading, we didn't get too much deflection. The tie rods were hard telephone wire micropressed to eye bolts run through the spars.

We had decided at the start to warp the wings, and this we did, even after reading that it didn't work years ago on airfoils that were more sensitive to changes of angles of attack than the Clark Y. We had the idea that maybe we were not so smart. We went ahead anyway, but instead of moving the trailing edge up and down, we moved the leading edge. Besides being simpler in this case to hook up, it looked like it would give faster, more positive control.

The engine used was a Homelight war surplus tank heater generator engine developing 7 1/2 hp on 15 cu. in. This engine was very heavy for the horsepower, and weight was 38 lbs. The original idea was to hop it up, as it was heavy enough to stand it. The idea was fine enough, but we never seemed to find the time.

EAA member Lester Robb carved several props, the last of which produced 34 lbs. of thrust, on the scale used to weigh everything that went into the airplane.

We found, on taxi tests, that the small prop would keep you cool, but wouldn't pull you very fast. But by laying down on the fuselage, it would taxi twice as fast. Now we were starting to learn something about frontal area, compared to prop length, and the effect on efficiency.

It was clear now that the engine should have been set back of the pilot. We had thought of this, but hadn't followed it through. The fuselage was built so that it could have been modified for the engine in the middle arrangement very easily.

It was during the taxi tests that the tricycle wheel bit the dust. A tail wheel was put on, which, though weighing five times as much, made steering much easier.

The covering was muslin, bought on sale for 10 cents a yard. This fabric tested 36 lbs. undoped. The rib stitching was waxed nylon cord used by Western Electric. By putting the covering on tight, we got by using two gallons of dope and one of thinner. This gave a clear, tight, but rough finish.

The airplane was assembled using hard telephone wire for bracing. We were going to use cable but didn't have time, as the Army had called, and I didn't have any time left.

We had hoped to keep the weight down to 150 lbs., so we lifted the airplane with a scale and a rope over a rafter. The airplane weighed 147 lbs., this with an engine that weighed 38 lbs.!

Since we knew that the engine didn't have enough power, and the FAA hadn't yet looked at the airplane (thank God!), we hooked a tow cable on to it with a scale at the tow car end. The airplane hopped right off very fast with 80 lbs. of pull at 22 mph in level flight. It took 30 lbs. of pull to fly the airplane at a very solid 30 mph. I had very precise control and the airplane was very stable. I think I would have let go of the stick if I had known that the stick wouldn't turn upside down. The controls were very light, except warp, and it didn't want to move out of center.

The airplane was assembled and flown one overcast Sunday afternoon. When the day was done, the airplane was disassembled with wire cutters and a saw. So, the airplane has been reduced to hardware, stovewood and memory.

If I were to build another one, just a few changes would be made... stronger, lighter material, and the use of aircraft building practices. Most of the fittings were cut out of an old gas tank with tin snips. I'd try the engine in the middle and let it go at that. We were satisfied with the controls and landing gear, but would stick the nose wheel out further in front and wouldn't put any more weight on it. (It only had 18 percent of the weight).

In designing this airplane, we went with the idea that what wasn't there didn't weigh anything, cost any money or cause any trouble. The idea behind this lark was the same as Ray Stits and his "Mosquito." We tried to cut building time and make it easier to build, plus controls that were positive at low air speeds, yet didn't absorb too much horsepower working.

I wish that I had had more time to fly the airplane. I would have liked to fly the airplane through all kinds of turns, cross-control and spin, and to learn if ailerons alone could fly it out. I've never heard of a warper being internally spun.

There were a thousand things I wanted to try with the warper. I don't know of anyone who has ever flown one with a stable airfoil to find out what they would do. As a matter of fact, I don't know of any built after 1918 or so, except by Pete Bowers. I am satisfied that warpers would fly differently, but not enough so to put ailerons on.

We were going to try go-kart engines that were put on the market since Ray Stits' airplane was built. Kart engines are a little like car engines, and they are getting more powerful all the time. I shouldn't think it will be too long before one sees a cheap one in the l5 cu. in. class. An engine of this size, producing 15 hp, should fly the airplane nicely. Working and playing with these little engines points to the fact that they burn lots of gas per hour. Fuel economy isn't one of their virtues. Vibration isn't any worse than on a 65 hp Continental.

I hope that this account will give someone new ideas, and the incentive to do some work on an ultralight aircraft. After all, a hot B class (7 cu. in.) go-kart engine in a 70 lb. airplane, and if you weigh 50 lbs., you're in business!

Seriously, ultra-lights aren't good for anything but playing with, but that's where the fun is. Here's an area where your ingenuity will show big. Let's see what you can do!

This one came from the July 1967 Sport Aviation.

A Wisp of Airplane
By Val Banes, EAA 2880
718 Broadway, Monett, Mo.

The era of the "minimum airplane" appears to be at hand, with a great deal of effort being expended in this direction by various people.

Wilbur Staib, EAA 31095, an old hand at building small airplanes, has done it again with a rig called "Airy-Plane." The only apparent design criteria for the craft was Staib's limited spare time and working and hangar space. So, it evolved that the airplane had to be something which could be built in a short time, and had to be built and hangared in his one-car garage.

The "Airy-Plane" is unique in that it is also a twin-engined aircraft, even though the powerplants are only 10 hp West Bend 820 chain-saw engines. The little craft nets at 175 Ibs., is only 14 ft. long, with a 14 ft. span. Three months and about $500 were spent on the craft.

Minimum may be an understatement where the fuselage is concerned. Except for the main cradle supporting the pilot, wing and landing gear, the rest of the fuselage consists of a high-strength steel tube to which the tail section is attached and held in truss by a system of rigging wires. This boom is removable so that the plane can be towed to the airport and stowed in the garage.

The engines are more or less inserted into the leading edge of the rather thick wing. They swing 24 in. Troyer wood propellers, and most of the early test flights were straight take-offs and landings to build up confidence in the little engines. Range is best not discussed, as the fuel is carried in two one-gallon paint thinner cans.

Starting of the engines is accomplished with a few yanks of the starting cords, and take-off occurs at about 50 mph. The "Airy-Plane" is no homesick angel with that kind of power, but the altitude was deliberately held down during the testing period. Think of the prestige a builder of such an aircraft can have when, with a handful of throttles, he has the power of a couple of engines at his command! Instrumentation is what might be called "basic." Actually, it consists of an airspeed indicator and a tachometer with a left-right toggle switch to pick up the reading from either engine. Space is available in the instrument panel for presumably an altimeter, if the need for it should arise.

Staib, who is presumably an inspector at North American's Rocketdyne Division, has a considerable background in sport aviation circles. He was the designer of the Carpenter "Special" biplanes dating back to around 1930, and has designed and built several other small biplanes in the years since World War II.

One of the designs resulted from a competition with Ray Stits who had, at the time, built a small low-wing airplane billed as the "world's smallest airplane." Wilbur felt that he could go Stits one better and built a still smaller, if similar, craft which weighed 390 lbs., was 11 ft. long, and sported a 7 1/2 ft. wing span. Ray Stits went on to design and build his little "Sky Baby" biplane which is currently in the EAA Air Museum. That seemed to settle the matter, and Staib subsequently dismantled the "Little Bit", as it was named, as it was a "hazard to the life and limb of Wilbur Staib." The parts of this airplane went into a small 13 ft. span biplane.

All told, the Staib "Airy-Plane", N-11V, looks like a winner, and plans may eventually be offered to the homebuilder.

So, now Wilbur Staib, who lives in Diamond, Mo., has yet another "world's smallest" airplane to his credit... the smallest and lowest-powered twin-engine aircraft!

The Windy was in the February 1968 Sport Aviation. At 450 pounds, it was not exactly an ultralight, but it would be right at home on our club field. I especially like the tri-engine version.