Vector II (oz6819)


Vector II (oz6819) by David Coltrin 1988 - plan thumbnail

About this Plan

Vector II. Radio control model. Pattern plane for .40 power.

Quote: "I love to fly, and to any that I am performance hungry would be quite accurate. However, being an engineering student on a tight budget, I found myself stuck with a tired old K & B .40 engine, a Futaba 4-channel radio, and no money to buy new equipment. Believe me, it is hard to find a kit that will perform really well on this equipment. After a long search for the right airplane, I gave up and decided to design one myself.

The Vector II was designed to obtain the maximum performance possible with a standard .40 engine, four channels, and no retracts. As I'm sure you realize, along with the benefits of retracts such as cleaner lines leading to lower drag and a sleek appearance, come some serious disadvantages, especially on a .40 sized ship. One problem is that the inherent weight increase that comes with retracts, although hardly noticed on larger airplanes, can take quite a large bite out of the performance of a smaller airplane. The vertical performance and the landing characteristics both suffer. Another problem is that in making room for retracts in a small airplane, some of the dimensions of the airplane must be enlarged. This increases drag and, at least in part, nullifies the positive aspects of retracts with regards to drag. And probably the most serious drawback to retracts is the cost.

The Vector II takes advantage of all these facts. It is light, fast, and a good, smooth flying pattern ship. Despite the fact that the model has relatively large overall dimensions fora .40 sized airplane, such as a 58 in wingspan, it is very light. The all-up weight with the K & B .40 is a meager 3 lb 14 oz. Even so, it is amazingly tough. This combination of light weight and sturdiness comes from the in-corporation of new construction designs for portions of the airplane which are mechanically superior to conventional designs. Whether you decide to build the Vector II or not, some of the ideas incorporated into this airplane could be utilized in a variety of designs to improve performance and appearance.

The airplane is also fast. I can honestly say that I could not have made the lines on this model any more aerodynamically clean than I did. It is the low drag coefficient (not the horsepower, certainly) which accounts for its high speed. Whether the model's appearance is pleasing or not you may judge for yourself. To me, beauty is just the icing on the cake, and the real meat of the meal lies in how the airplane flies. This airplane's outstanding feature is that on top of being an excellent performer, it is a very smooth flier. It tracks wonderfully, making maneuvers seem easier to perform, and it looks controlled and graceful. This is due in part to the model's unusually long wing and fuselage dimensions, providing large axial moments and rotational inertias.

Construction. At the risk of sounding a bit like my engineering professors, I would like to address briefly the topic of stress on beams (wing spars). To most, this will not be new, but to all it should be a good review. When a beam is under a load, the highest stresses are at the surface of the beam. Therefore, when a beam fails, the crack or deformation begins at the surface and travels inward..."

Supplementary file notes

Article, thanks to hlsat, JHatton.


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