WBP-1 Flying Plank (oz14410)

About this Plan

WBP-1 Flying Plank. Profile scale model pusher, for rubber power.

Quote: "THE WBP-1 Flying Plank. Al Backstrom offers a model of his unusual aeroplane.

From my boyhood I have been fascinated by tailless aeroplanes and sailplanes including models of them. This led to the design and construction of flying plank type sailplanes in the '50s. Several duplicates have been built over the years and some are still flying.

The full scale WBP-1 aeroplane was aerodynamically based on these earlier sailplanes. It is not a powered glider but has always been intended as a powered craft. It has a good glide ratio with the engine stopped but I was never sure of this until it had an actual engine failure.

The design objective was to create a machine with the performance of normal light planes, but one that used minimal power. Due to engine availably in the early 70's when it was designed and built it wound up with a larger than intended engine.

The WPB-1 was flown extensively after early engine problems were solved but low engine reliability convinced me to put it in a museum rather than waiting for another engine failure in a very bad position. It is now housed in the Air Power Museum at IBlakesburg, Iowa in the US.

The model: The model is so simple there is very little to say about construction. Do not glue the anti-warp strips on the wing until it is installed in the fuselage and glue the anti-warp strips to the tip fins before gluing them to the wing. Use your choice of thrust bearing but use a large headed pin to form the front hook. The large headed pin will assure that the model doesn't stick into people, etc.

Do not cut the elevon area free at the inboard end and do not glue the tip anti-warp strip to the wing aft of the hinge line of the full scale aircraft. If you plan to fly the model outdoors you should apply a couple of very thin spray coats of lacquer.

Use your choice of propellers. I initially used a 6-9 light balsa prop but the model was very sensitive to thrust-line adjustments. The model did not require nose ballast with this prop. To reduce the sensitivity of thrust line adjustments I changed to a 5-1/2 in North Pacific plastic prop. This prop reduces the thrust line sensitivity but does require nose ballast with the rubber used.

To trim the model make a motor approx. twice the length between the hooks of 3/32 to .110 in rubber strip. Double this and install it on the model. Check the balance point it should be as shown on the drawing. Set the outer ends of the elevons up 1/16 - 3/32 and tack glue to the wing tips. Test glide the model. Correct a dive with more up elevon. Correct a stall with more weight on the nose. When a satisfactory glide is obtained install the rubber as a single loop and wind about 200 turns..."

Direct submission to Outerzone.

Supplementary file notes

Article.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction