About this Plan
Finnair. Free flight towline glider. Contest winning A/1 class glider from Finland by Ilpo Haahtela. September 1957 Aeromodeller.
Quote:- "FROM TURKU in the southwest corner of Finland comes this neat and workmanlike A/1 Glider that has achieved excellent results in Finnish contests where competition in the A/1 class is keener and better supported than in Great Britain. For those who do not know, or whose memories are a little rusty, we quote the A/1 formula as follows: 18 sq. dm. maximum projected surface area, and loading of 8 grammes per square dm. minimum, which becomes 279 square inches maximum for a minimum weight of 5.08 ounces. In FAI events, the loading is increased to 7.61 ozs. min, and Finnair prototype weighs 7.7 ounces.
Designer-builder Haahtela of the Karpanen club is at Turku University studying natural sciences, in particular, zoology. He points out that the problem of building down to weight does not arise with the A/1 class, hence the ply ribs spruce spars, etc. Built in this fashion the model will withstand the roughest treatment without coming to harm and has an average still-air duration of approx. 2 min.
The prototype needed a touch of right auto-rudder setting for towing and a tight circle to the left on the glide is recommended for best results. Slightly more than the minimum ballast weight is also suggested and we gather that with the above trim the original climbs fast and straight, and as the designer puts it - 'Goes easily up in thermiks'.
Ilpo confirms our own experience that A/l gliders due to their smaller areas are not so happy under windy conditions as their bigger brothers, particularly when it comes to fast towing. He does guarantee, however, that Finnair, which is the ultimate development of a whole series of A/1's, will tow up fast without any weaving straight overhead, curving away to the left immediately after it is cast off.
Construction is orthodox although balsa cement is best replaced by a slower drying glue such as 'Durofix' when it comes to glueing spruce spars to plywood ribs. Ilpo recommends double covering for the wing as follows... "
Update 08/08/2017: added article, thanks to RFJ.
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by Ilpo Haahtela
all formers complete :)
got article :)
Found online 19/11/2011 at:
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