I am just finishing up two planes that I will be flying this flying season. I am looking forward to a good year of stick time without having to spend time building. Don't get me wrong, I love to build. I just don't like being in a position where I have to build when it is flying weather. At any rate, I am sure this will be a bumper year for model airplanes.
Airplanes have a tendency to roll around inside a van or pickup truck if it is not supported in place. I use wheel chocks made of 3/4-inch plywood. The chocks are about 12 inches long and 4 inches wide. I cut out an opening about 1/8-inch smaller than the size of the wheel at the 3/4-inch height. This allows me to slightly squeeze the wheel into the wheelchock. To keep the wheel chocks stationary, I put four nails in from each comer and cut the nails off leaving about 3/8-inch protruding so the nails will grip the carpet.
While this works great for vans, pickup trucks need a platform with the wheel chocks attached to it. The tail wheel should also be anchored. I usually throw a blanket over the tail. The blanket is heavy enough to keep the tail down in hard breaking. I have used this method for many years and I find that the planes do not shift during travel.
Bob Stocksen, a long time friend from Olathe, KS, has built a nifty hanger or stand to store his planes. Made of 2x4's and some scrap plywood, one can easily stack 3 to 4 airplanes. The hanger consists of two upright 2x4's with a 12 inch cross member at the bottom and attached to the floor joists above.
On each side of the upright 2x4's, a 2x4 is attached horizontally at each location that a plane is to be stored. A small piece of 2x4 is hollowed out slightly so a tail wheel will move around too much. This piece is attached to the horizontal 2x4's at the rear.
A piece of 2x4 is cut for the main gear support. On the each end of this piece are small 2x4's about 5 inches long that has a curved cutout to accept wheels. This curved cutout helps to keep the wheels from getting a flat spot from sitting for a long period of time. At the ends of the main gear support a piece of scrap plywood is attached to keep the gear from shifting from side to side.
He has also added a tray under the plane for storage of components like outer wing struts, bolts, etc. He keeps the radio lying on the horizontal cross members. Everything pertaining to the plane is all in one location.
Gerry Benoit, of Agawam, MA has a secure way of retaining the tail end of a plane while starting an engine. The base is made of a 3/4-inch thick floor Mange and 3/4-inch galvanized pipe threaded into the floor Mange. This is pounded into the ground. A pilot hole is started with a piece of steel rod so the base can be pounded easily and straight. The tail retainer is made of 1/2-inch copper waterline (galvanized pipe, similar to gas line, with the elbows soldered to the pipe can be substituted for more strength). The copper water line is covered with foam insulation. His club has several of the retainer supports spaced about 20 feet apart and each pilot has his own retainer.
(Note: I am not in favor of tail retainers on planes bigger than the 120 size. However, I have witnessed larger planes being started this way with no ill effects. I just don't feel this is the safest way to start an airplane.)
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Bob has been involved in building model aircraft since 1948. Becoming more involved in R/C in the early '70's, he has made this his major interest. The best times to call are 7:30 a.m. to 3:00 p.m., or 4:00 p.m. to 7:00 p.m. PST. He accepts VISA and MasterCard purchases with a $20.00 minimum order. You can also visit his page on the Internet - http://imt.net/~ims/scale.html
Many kits use longerons glued to plywood sides to form a basic box construction. Some of these kits use formers cut from plywood. Others use a simple cross member. This method leaves a weak joint between the fuselage sides and the cross members. I like to add gussets to greatly strengthen the joint.
I generally make them from liteply in the shape of a 45-degree triangle with the short sides measuring about 4 times the thickness of the cross member. If balsa gussets are used, then the grain needs to run parallel to the cross member. For extremely strong joints, a gusset can be added to both sides.
I have covered this topic before but some builders are not taking full advantage ofthe method of pinning the engine box. I see firewall pinned but no pins through the firewall into neither the triangle stock nor the box side through the triangle stock. I also see balsa triangle stock used. This should be a hardwood. In response to requests, I will again cover this topic.
My preferred method is pin and fiberglass the box. First, I generally make a firewall 1/2" thick by using two pieces of 1/4" plywood laminated together. If my engine has a cup mount, then I cut a hole in the center to lessen the weight. I make this hole as large as possible and still retain the integrity of the firewall. If I am using an engine standoff, then I will lighten only one of the two 1/4" pieces of plywood.
The box itself is generally made of 4 pieces of 1/8" plywood as shown in the drawing. After the plywood firewall is laminated, I then sand and true up the sides for a slightly snug fit into the engine box. I knock down the corners slightly to compensate for the slight buildup of glue from gluing the box together. I also slightly bevel the sides for right thrust and down thrust if required. At this point I lay out the mounting holes and drill them. If I am going to include right thrust, I will move the engine mounting holes towards the left about 1/8" so the spinner/hub will still be close to the center of the fuselage, and make final adjustments to the cowl so the spinner/hub will be centered over the cowl when mounted.
I adjust the engine box length to fit the engine length plus 1/8" so when the cowl is mounted the spinner will be 1/8" in front of the cowl. I now glue the firewall into the engine box. If there is a good fit, I use thin C/A liberally followed by thick C/A. If the fit is loose, then I will use epoxy. I then sand the front of the box flush with the front of the firewall and slightly round all corners.
I lay out the supporting hardwood triangle stock for the inside of the firewall. I cut the ends at a 45 degree and mark any triangle stock that needs to be trimmed for the blind nuts. I glue hardwood triangle stock to the back ofthe firewall and add 1/2" balsa triangle stock to the inside corners of the box sides.
It is time to pin the engine box assembly. I cut a 1/8" dowel into one-inch long pieces. On each side of the box, I drill 5 holes into the side of the firewall and 4 holes into the triangle stock (watch out for the engine mounting holes). I will also drill 3 holes for each side ofthe front of the firewall. These holes run through the firewall and into the triangle stock. All holes that go through the triangle stock will run completely through. To glue the pins in, either use thin C/A liberally inside and outside the box so it penetrates the joint, or epoxy. (The epoxy will have to be worked into the hole and the pin will also have to be coated prior to placement.) The pins are tapped in with a small hammer (prior to C/A gluing, after epoxying). After drying, cut the pins off flush and sand smooth.
Finally, as an option, I fiberglass two inches around the box and place balsa triangle stock around the box on both sides of the front former. This box is usually the only thing that survives after a crash.
Silver solder is preferred over soft solder for linkage hookups. I am not referring to the 45% silver types but rather the 5% type such as Stay-Bright silver solder. This is much stronger than soft solder. I have yet to see one of these solder joints fail. Usually a soldering iron is not quite hot enough to use silver solder. I use a propane torch turned down to a small flame and in a few seconds the joint is ready to be soldered. Usually an acid is used instead of flux paste. Just a drop of the acid on the joint is all that is required. Also let the acid sit for about 30 seconds so it etches the metal. It is very important that you wash the acid off with water after the joint has cooled or the metal parts will rust badly. Also the acid will make any small cut on the hand burn like crazy as well as eat holes in jeans.
Contact Bob Banka's at Scale Model Research, 3114 Yukon Avenue, Costa Mesa, CA 92626, (714)979-8058.