Have you weighed your landing gear lately? It is surprising how much the simplest gear weighs. Two pounds is not uncommon for a twenty pound airplane. Of course, this includes wheels, pants, struts and etc. However, ten percent of the gross weight of the plane for the landing gear is a bit much in relation to full scale practice. We do land a little harder occasionally. Accordingly, it is nice when the gear saves a prop or prevents some structural damage because it is somewhat more rugged than required for "normal" landings.

We have all been frustrated trying to straighten a gear strut(s) on the field after a hard landing. It is sometimes very hard to "unbend" the gear or to remove the gear from the plane to make the job easier. A completely different gear design could possibly solve some of these difficulties. What is needed is a stronger, lighter and easier to maintain gear.

The adequacy of the basic gear used in six of my airplanes has been proven during the last ten years. The ruggedness and maintainability has been very satisfactory in the course of a few thousand landings. This new experimental gear is an attempt to address the weight concern. Perhaps a slight increase in complexity has resulted in construction using all steel parts and some high temperature silver soldering.

However, commonly available tools and supplies are all that are required. Even the silver soldering is pretty simple and is fun to do after you learn how to do it (see the Spring issue of High-Flight, page 48).

The gear shown in the drawings (Figure 1) was specifically designed for my new scratch designed airplane "Desert Storm," a 17 pound shoulder wing monoplane. The airplane was built during operations Desert Storm. Parts similar to parts 6 and 7 have been tested over a ten year period. However, the silver soldered part 6 has only been tested about 25 flying hours in POGO IV with no problems. The red hot temperature required for silver soldering does mess up the temper in the area of the joint, but the gear has survived a few hundred landings with no distortion.

Although this gear is more complex than the usual aluminum type, it has several features that I fee1 are worth the extra effort. Only a small hole in the fuselage is needed to insert each gear leg, making a cleaner installation. The easy gear removal is nice for transportation and maintenance purposes. The vertical and longitudinal stiffness can be readily tailored to the particular airplane. It is certainly inexpensive, although cost is not a factor. Weight can be saved in the gear and its mounting structure by careful sizing of parts.

The gear strut, part 6, uses 7/32" and 5/32" piano wire to provide the stiffness in both directions for a 17 pound airplane in only moderately hard landings. Gear drag puts part 8 in tension to resist this force. Gear spreading forces are put into the fuselage structure by parts 3. In any case where this structure may not be strong enough, the two parts 3 should be connected by a silver soldered tension wire (of 3/32" diameter for this 17 pound airplane).

Parts 1, 2 and 5 are 1/16" soft steel. Parts 3 are bent 90 degrees at the dotted line. Parts 5 are bent a few degrees depending on fuselage width. The drag wires (8) are silver soldered into parts 5 and 1. Drag wires 8 should be bent 90 degrees into parts 5 before silver soldering. The length of wires 8 should be determined in final assembly before silver soldering to part 1.

Part 2 is made from a 6-32 threaded rod or a long bolt. It is heated to a red temperature with a propane torch and bent around a rod of the right diameter. Parts 4 are made from 1/4" square soft steel stock (hardware store item). The slot for the gear wire is made by drilling, hacksawing and filing. Parts 4 were drilled and tapped for 6-32 socket head bolts. Note the clearance drilling of about 1/8" depth to make tapping easier. The bolt spacing should be done accurately to place the bolts against the largest strut wire. The slot in parts 4 should be of the same diameter as the forward strut wire.

T he notch at the top end of parts 6 is relatively easy to cut in the tempered wire. Put part 6 in a vise and use a hacksaw to cut the notch to the width of the wire diameter. The saw cuts are placed at each end of the notch then additional saw cuts may be done in between to make filing out remaining material easier.

Part 7, the landing gear fairing, is made of balsa. All grain should run in the fore-aft direction to allow for the flexing without breaking the balsa. I have used both Monokote and Worldtex covering on the balsa. Glue the balsa fairing to the wire strut at one end only. Swelling and shrinking from summer humidity could crack the balsa and the covering.

Socket head screws were used throughout this installation. "T" nuts were used in the wooden structure for the bolts from parts 5 and 3. This makes it easier to remove all gear parts. The answer to the question at the beginning of this article is "yes." The gear that I have been using for 10 years weighs 2 lbs., 4 oz. The new experimental gear for an airplane of about the same weight weighs 1 lb., 7 oz. This 36% weight reduction does involve smaller wheels, wheel pants and strut wire size. The old gear was admittedly designed for "student landings" and used two 1/4" piano wires in each strut. The flight log that I have kept for several years gives me considerable insight into the service seen by several airplane systems.

For example, I made a total of 1056 landings with POGO III, POGO IV and Floyd Bean Special airplanes in 1990. This involved 59 hours flying time and 13 gallons of gasoline. The number of landings made each year is about the same, requiring a tire change about every six or seven years.

Early experience with aluminum wheel bearing was very bad in terms of lubrication and the sizing up of the wheel on the axle. This major problem was solved by reaming out the aluminum hub and inserting simple brass tubing bearing locked to the wheel hub.

This gear was given a very good test as this was being written. I made one of those "3 D" landings (dead stick, downwind and dumb) in the process of tuning the new engine. Although definitely not planned, this landing was all a designer could wish for in testing a new design. ("Desert Storm" before and after "3D" landing!)

In summary, the gear did exactly what was desired. The struts were bent in the area between the fuselage and the wheels. There were no bent or broken parts in the fuselage. The struts were easy to remove and straighten, and even the strut fairing only needed to be cleaned before re-use. The gear repair only took about fifteen minutes but the fuselage repair required about eight hours!