|When considering a new airplane it’s perfectly reasonable to stick to proven shapes and numbers, or to carefully develop our last successful design to an ideal shape. Sometimes however the urge to get out of the rut becomes stronger; especially if we have more than one airplane in our hangar which allows the luxury to choose their use depending on flying field, weather, and mood.|
trapezoid wing planform is probably the easiest to build, thus providing
for simple rigid construction at modest weight. With my building skills
I wouldn’t ever consider an elliptical wing shape. But something which
comes close to this shape can be a satisfying solution. After all there’s
the Thunderbird wing and similar designs which prove that aerodynamic requirements
and aesthetical viewpoints can mix very well. That’s how my new design
In the past I have published a few plans in a German magazine and in the British “Aeromodeller”. For these articles I needed pictures, so I took some photos during the construction process. On my latest building projects I tried to shoot a comprehensive photo sequence. This can represent a step-by-step instruction for the whole construction work. Since the complete work includes up to 200 pictures I cannot show this on the Internet. Instead I’ve chosen those segments which deserve special attention or where I differ from the norm.
For a better view a click on the thumbnails will open a larger picture.
|Rib production is explained in full detail on another page on this website. Just a short note: to get really symmetrical rib templates I only draw the upper half of the airfoil around a centre line. The paper is then folded along this line and the outline carefully cut with a very sharp knife along the drawn rib outline. That way the rib contour is 100 % symmetrical. Short pieces of spar stock help to precisely shape the spar cutouts.|
|It really helps to number the ribs. If the stack ever falls down you’ll have a hard time to collect the right pieces together again. I cut lightening holes on the inboard ribs only since the outboard wing half can be a little heavier anyway.|
|As a jig I use “negative” ribs : two each at the root and at the tip. These are cut from the original rib templates. Also there are about 20 little blocks to support the leading and trailing edge plus a tapered balsa strip to support the main spar. The whole setup is covered with transparent foil which will not adhere to cyano glue.|
|Bending the undercarriage wires is a big pain for me. It is helped with a very precise drawing and a wire bender with long arms. The gears are provisionally glued to the gear platforms and painstakingly arranged with the help of especially built templates in order to provide exact alignment.|
|On detachable airplanes we need a means to connect the elevator pushrod. I use a “two horn” version which gives me a wide freedom to select control surface deflections, plus choice of deflections in relation to each other. Of course both pushrod lengths are adjustable. To set the “flap pushrod” length correctly, I use a “help template” with the correct 90 degree pushrod/horn arrangement drawn on a piece of plywood, which is slid on the wing next to the horn. The inboard wing tip is built as light as possible. For the outboard tip I don’t care about weight.|
trailing edge of the stabilator is built up by three 1,5 mm ( 1/16 in )
strips forming a ( horizontal ) “U”. The vertical piece is strengthened
with carbon veil.
The engine compartment is filled with blocks and “dremelled out” as necessary .
|Detachable parts require some special attention. The “fuselage bottom part” ( as I like to call it ) has to be prepared very carefully. It is built up with the wing resting in the fuselage laying upside down.|
|. The shape of the mounting “tongues” is best found by cutting paper templates. These are transferred to plywood and sawn out precisely. The rear tongues should never be glued separately to the fuselage respectively fuselage bottom part. That’s a problem waiting to happen ! I bolt them together before gluing them into to fuselage sides. This prevents incorrect installation and possible mounting tension. Of course we have to make sure to not glue things together which shouldn’t !|
|For many years I have shaped the fuselage top out of balsa blocks. A much lighter and stiffer version is to use shells. Yes, it’s much more work but worth every minute. First we need Styrofoam moulds, a negative and a positive form. The shells are made from very light balsa sheets. For ease of production I use double layers : two layers 1.5 mm for the fuselage front, two 1 mm layers for the rear part. The sheets are soaked about ½ hour in water ( I didn’t find ammoniac to help ). The layers are bonded with thinned white glue and left for about three days to dry.|
My fin looks a little complicated. Because of the adjustable elevator horn the rear end of my fuselage is somewhat wider than usual. And since the rear end has to provide enough room for the rearward moving horn, the bottom part of the ( detachable! ) fin has to provide this space. This makes for a somewhat complicated construction and for some problems with weight.
The wheel pants consist of several parts. After gluing together the blocks and roughly shaping the outside, they are broken apart and finished inside. Great care is required to glue them together on the wire strut and to align them correctly.
the covering I copy an idea developed by Henk deJong. All open areas are
covered with light silk first. After this EVERYTHING is covered with light
tissue ; also the silk covered areas ! The silk makes for a rigid covering
which protects from falling screwdrivers and similar attacks, the tissue
provides the base for a good finish.
The front fuselage (until behind the canopy ) and the engine cowl are covered with glass cloth and epoxy. At last the recess for the canopy is cut ( oh how I hate this task ! )
|This story deals with the constructional phase only. I will not give any information about finishing here. There’s much better expert advice available elsewhere than what I can give. I’ve added a treatise on how to design a pleasing colour design on another page of this site. It’s based on my latest airplane but provides general rules of design.|
|Those who are interested in seeing a reduced size plan of my latest creation can download a DIN A4 ( 11 x 8 ½ in ) size drawing HERE. For a full size plan you can contact me via Email ( see “Contact” page ).|