The MX

This was by far, the most popular plane ever built. The number of planes produced nearly matched the entire GA and Military fleet for the year 1982. Easy to fly and with the MXII to teach new pilots, the popularity of the MX almost exceeded that of the Piper Cub.

Eipper Formance was rather particular in choosing dealers for their products.
Requirements were beyond the casual sunday flyer. A larger percentage of their dealers were full time ultralight dealers. A training aircraft was required, an instructor was necessary and a minimum inventory was required. All this contributed to a professional sales force that made the product and the pilot look good.


The first MX was reminiscent of the early Wright Brothers plane in that it had a center mounted yoke. This version of the control system quickly was replaced by the present control stick. The MX mounts the stick just to the right of the seat. This offers easy access to the plane and keeps it safely out of the way.

One of the better features of the entire line of Quicksilvers over the years has been the preparation of the kits for delivery to dealers and customers. Every part is numbered with a part number sticker. Every smaller part is attached to cardboard by means of blister packaging. This keeps every part fresh, clean and in numerical order for assembly.


Eipper spared no expense in selling their product. Colorful brochures were printed and sold at reasonable prices to dealers. Getting a new mailing from the factory was very exciting. It always contained a new shot of a fancy and colorful sail pattern, new design changes and dealer information. Sails were all made is house and in rather large quantities too. This picture shows one of the 'flagship' MXs and another pretty sail pattern.

As the early years matured the line of aircraft, the sail patterns slowly evolved too. Most material sold for sails was dacron, 36 inches wide and a pretty variety of colors. Due to the volume of sail material and the need for better color schemes, a dyed three color material was purchased in the necessary large quantities to justify the dyeing process. This material offered an easy way to add multiple colors to the solid ones, creating an ever more colorful sail. The first of these dyed panels was three colors, the Eipper colors as I called them, red, orange and gold. The later dyed panel was the same colors in narrower bands with a four inch black stripe at each edge. Also purchased in the early 80's was a four color panel with dark blue, dark green, light green and yellow. These sails were very popular and very attractive.

While the plane itself always looked the same, changes were made almost every month. I would open a kit and find a new bolt, or some bolt size would have one or two less in quantity. These small changes were almost unseen by the average looker, but slowly made the MX line of craft the safest in the world. Most changes were minor resulting from trying to save weight, or make a part by a more expeditious method. Some were due to field problems. While the total changes were too numerous to discuss all of them, I will mention the ones that may still linger and cause problems.

1) Grade five bolts should be used for the coarse thread fittings. Grade eight is much to brittle and also more likely to have corrosion problems due to moisture. This came out in May of 1983. Even today, the GT-500 uses these grade five coarse thread bolts for the compression struts and in the tail parts.

2) The bearing for the lower shaft was changed to an LP-16 rather than the light weight type used on the Yamaha models. The present choice for this bearing is an expensive squeezeloc style which does not score the drive shaft at all. It should be installed with loctite however.

3) Two items which got little press or publicity, but caused my customers problems were the need for a push-pull restraint cable and changing the seat mount to one made of steel rather than aluminum. One customer bounced across a low curb taxiing to a take-off point and the push-pull tube hit the prop. The other incident was caused by doing aerobatics with the aluminum seat frame. Suffice to say, the plane and pilot are OK but we needed a small crane to remove the inverted plane from a tree.

4) We saw the early need to remove all of the pip-pins, push-pins, ball-loc pins or whatever from the airframe. These items offered no preload to joints and also were subject to falling out if a small piece of dirt or sand got into them. These should all be replaced with bolts.

5) The push-pull cable under the seat received a lot of abuse from pilots stopping planes and getting their legs back under the seat too far. The teleflex guard kit was offered as a means to stop this. The kit also had positive stops for the aileron or rudder control.

6) One item that was fixed by the factory and we fixed better is the balance strut on the rudder. This tube was originally attached to the vertical tube with a grade 5 bolt. This didn't hold the tube very well in relation to the rest of the rudder and the trim of the plane could be varied by rough handling of the rudder.
The factory fix was a small set of plates which more securely aligned the balance strut with the rest of the rudder. We also have available a much larger set of plates which do a much better job than the little plates used by the factory.

7) An important item, although I know of no problems as a result, is the cracking of the root tube at the aft spar attachment channel bolt. This bolt is a short bolt, installed prior to the prop shaft being installed. There are two of them at the rear of the shaft. The under side of the bolt head has a rather sharp corner. During hard landings and minor crack's, this sharp edge coins the inside of the root tube. This crack will propagate around the root tube due to the torque and fatigue cycles during operation. The crack is easily seen and the fix is to replace the tube, and install a large area washer under the head of the bolt. Assemblies with the washer installed will have only to threads showing beyond the locknut. Assemblies needing fixed, will have about four threads showing. This is an important change to older planes.

8) Another important change is the wire shackles at the tri-bar crosstube and the top of the kingpost. These shackles started as an item used in the sailing industry. It was a round cornered forging. Problems arose with this part and it was replaced by a machined plate part bent into a u shape. This part has more or less square corners. The original round forged shackles should be immediately replaced.

The MX was a neat plane, easy to fly, fix and even buy for many people. I was always making small changes to the basic design since I was usually there when something broke or wore out. One of the neatest things I changed was installing a 64 inch prop on an MX in 1983. I used an 8 inch pulley with four grooves that was left over from a Pteradactyl disappointment. The small pulley was the stock four groove Quicksilver. I mounted a shaft just above the root tube in two pillow block bearings. The prop bolted directly to the pulley.

This was a sweetheart of a drive compared to the 52 inch standard props. Thrust was comparable to the 503 and 52 inch prop. Fuel usage went way down and the noise was reduced a great deal too.

Another interesting change was done at the request of a customer. He and a friend had both purchased new MX's. His hangar was going to be his farm equipment building but the large door was only just wider than 30 feet. I very reluctantly cut the spars and the sail was restitched a foot shorter on each end. Both planes were identical with the 377 for power except for the clipped wing. I test flew both prior to the owners and was happy to see no difference in take-off speeds, climb rates, etc. He was elated to find that the clip wing went about five mph faster too.

This led to many changes to the MX airframe. We installed the tapered stabilizer, lowered the dihedral, added lower tail tubes and many other changes. The MX flew better and better. This picture shows a highly modified airframe which still retained the original 1982 Cuyuna engine. Cruise is 55 and top speed is over 62 mph.


This plane has been owned by several people over its sixteen years of existence, each added or changed a small part, some even flew it on floats. A hard landing just following this beach photo, sunk it in fifteen feet of water.

Another nice example of a re-manufactured MX is this one from Mt Vernon, Illinois, which is north west of me about 65 miles. He has many of the improvements discussed here and the plane flys very well.
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