"(F)looper" is the Dutch follow-up to the very successful American "Delta Dart" design, which originally introduced me into indoor modelling! Because Ebele Schouwstra (who runs a big school-modelling group) wanted a simple beginnersmodel for his club, he asked me to design and build a model to his specifications. The model should have a triangular wing shape in order to prevent wing warps as much as possible. In addition the design should meet the following requirements:
These goals were met by using a large asymmetric wing, but still with low aspect ratio in order to maintain a reasonably wide chord near the tip. The big area assured a low wing loading. We chose a long tail moment arm, a feature which Ebele and I strongly support and which you will find in most of our beginners designs. After a few test flights it was clear that the model was a good design and we introduced it as one of the first models a beginner builds when he joins our club.
The rear hook and the propeller bearing are distinctly different from other beginners models. This design is much easier to make. The somewhat larger friction in the plywood bearing doesn't noticeably influence the models performance. The wing should be glued to the fuselage with regular balsa cement. All other parts are glued with thinned down balsa cement. The plywood bearing is best glued with aliphatic wood glue! The propeller is from plastic and weighs only 2,6 grams. This is one of the reasons for the fine performance of this model. It is important to avoid brittle wood for the motorstick (density ±14 gr/cm3) . The paper covering should be ironed before applying it to the wing frame. Otherwise it will shrink later and distort the wing shape.
Specifically for this model we designed a special spar cutting tool, which allows a beginner to cut tapered spars easily. Against one side of a base block a plywood stop-block is glued, one at each end, which has a cut-out in it with the same width as the spar width to be cut. Cutting a spar is done as follows: cut a sheet of balsa to exact length of the spar and lay it on the jig. Shift it between the cut-outs and against the stops. Position a steel ruler along the stop-blocks and cut the spar with a razor blade. The razor blade slides along the outside of the baseplate hardly touching it and it cuts through the balsa in a single pass. For the (F)looper you need two different cutting tools, one for a spar tapering from 4 mm to 1,5 mm and one for straight spars of 1,5 mm width.
Since its introduction several hundreds of (F)loopers have been built. A beginner easily overlooks the asymmetric shape of the wing and can apply the covering on the wrong side of the wing. Even when the wing is glued to the fuselage the wrong way around, the model still flies. You may need a simple trim tab to correct the flight pattern. When you spot the problem early enough you can also glue the wing top-side down with the spars on the upper side. Will have no influence on performance! The only modification which might be considered is lengthening the motorstick a little to allow longer rubber motors. You should then also increase its cross section or choose harder wood.
Although the model usually flies straight from the board it can still be necessary to put some more up elevator into the stab. Continue decreasing the stabiliser incidence till the model flies close to stalling and than go back a little. The model is fairly insensitive to down-thrust. When you give the model a lot of up elevator it will fly loopings under high torque. You could oppose this with downthrust, but I have not tried that. And why should you? After the loop there will be a wing- over, and the model will continue to climb as if nothing has happened! This is where the FUN part enters and where the kids enjoy this model most. The model doesn't perform loopings easily, but it sure CAN do it when you make the proper trim adjustments. In our competitions we have introduced a bonus of 15 seconds for each looping performed during a flight! Believe me, this gets the kids going!
You may be amazed by this story, but the models flying characteristics are really great. It recovers easily from the most weird positions and still is fairly insensitive to changes in trim. The model is easy enough to build for 8-9 year old kids. Average flights are about 90 seconds but the record is already over 2 minutes. These times have been achieved in 8 meter ceiling sports halls. Some kids have also flown the model outdoors, but don't do this on your local sports field! We have seen 8 minute thermal flights ......!
After four years the (F)looper class is now an established beginners class in Holland. Only juniors up to 18 years may enter competitions. Many special beginner classes have been introduced over the years. Not all of them fully achieved their goals. For instance because some experts (to mention just something extreme) started to twist and carve on the plastic propellers ..... It is impossible to create a true beginners class as long as you allow experts into the competition. Even in this (F)looper class we 'gently' encourage the more talented fliers to move on to F1M or other classes when they start to dominate the competitions.
A propeller which suits the (F)looper perfectly is sold by SAMS. This is a 7" Sleek Streek propeller, diameter 180 mm and weight is only 2,6 grams. Address: SAMS, The Chapel, Sandon, Bunting- ford, Herts, SG9 OQJ, United Kingdom, tel.: 01763 287606, fax: 01763 288490, e-mail: aeroplanes@samsmodels.demon.co.uk
A good alternative is the 7" silver Peck propeller, item nr. PA022. Peck-Polymers, P.O. Box 710399, Santee CA 92072, USA, phone (619)448-1818, fax (619)448-1833, E-mail: PPModeis@aol.com.
