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Aviation History
1946
1946 - 0093.PDF
jANUAKY I7TH, I946 FLIGHT A- Norwegian Amphibian Twin-engined Civil Flying Boat with Wheel and Ski Undercarriage : Ten Passengers and Crew of Two BEFORE, during and after the war we in Great Britainalways found much to admire in little Norway.During the occupation we learned something of the way in which the Norwegians, in spite of tremendous diffi-culties and much suffering, managed to thwart the Nazis in all sorts of ways. We came to know many Norwegianairmen, whose work was held in high esteem by the R.A.F. KingHaakon was a popular figure during his stay here, and we came to re-gard Riiser-Larsea as one of us and were sorry to lose him when he re-turned to his native land to take up a very important post. Making a Start And now, with the Royal Familyonce again safely back in Oslo and Norway once more master in herown country, we have cause to admire the way in which she is set-ting about the difficult task of get- ting back to normal. Even in thematter of aviation Norway is losing no time in making a start. A Nor-wegian firm has designed and begun -.onstruction of a ten-seater amphi-bian, a project which may well lead not only to Norway being self-sup-porting in this particular class but may even be in a position, pre-sently, to export to other countries. A very complete mock-up has beenbuilt already, although the detail drawings must obviously have hadto be produced in secret during the German occupation. The firm in question is B. Honningstad A/S, of Skoyen,near Oslo, and the new machine is known as the type 5A. In a general way it is of orthodox design in that it is ahigh-wing monoplane (to place the airscrews clear of water spray) with two radial engines mounted from the leadingedge of the wing, and sponsons for lateral stability on the water. On closer examination, however, it is found thatthe design incorporates certain not very common features, notably in connection with the " amphibiousness " of theundercarriage. British aircraft designers have, on the whole, not beenvery fond of using sponsons, the general opinion being that they tend to make for "' dirty " running, and outboardwing floats have been used on practically all British flying boats. While they do undoubtedly make for cleaner run-ning, they suffer from another disadvantage, that of vul- nerability. When a flying boat isin trouble on the water the cause is nearly always the collapse of a floator its supporting struts. Neat Wheel Stowage In the case of the Honningstad5A there was very good reason for choosing sponsons. With theirprimary function as lateral stabili- sers they combine that of support-ing the land undercarriage, and by a very ingenious arrangement thiscombines wheels and skis. The general scheme is shown in an illus-tration. To the wheel axle and undercarriage struts is attached aski in such a way that the wheel projects slightly through a slot inthe ski. When the undercarriage is retracted, the ski fits snuglyagainst the underside of the spon- son, and about one-quarter of thewheel diameter remains exposed. This probably atlds but little tothe drag, and when the undercar- riage is lowered the machine can beput down on a grass airfield or on the ice of a frozen lake or on asnow-covered field on which the snow is of too soft a nature toprevent the wheels from sinking-in. It has always been the extra* weight and complicationof the land undercarriage which has prevented the amphi- bian flying boat from becoming really popular. Accordingto our Oslo contemporary, Norsk Fly-Tidsskrijt, to which we are indebted for this information and for the illustra-tions, the disposable load for the plain flying boat is 2,050 kg. (4,500 lb.). For the ski/wheel amphibian thefigure is 1,690 kg. (3,725 lb.) so that the weight of the combined land undercarriage is apparently 775 lb. Thismeans that for relatively short stages (435 miles) the weight of mails and parcels is re-duced from 465 kg. (1,025 lb.) to about 105 kg. (230 lb.). One may regard a loss in payload of nearly800 lb. as a very serious one. Much will, of course, depend upon the; geographical and cli-matic conditions on the route on which the machine is to be used. It must be rememberedthat Norway has been liberally supplied by nature with fiords and lakes, whereas the pos-sibilities for establishing airports are distinctly limited, owing to the mountainous nature ofmost of the country. The fact that the machine can alight on fairly soft snow shouldhelp to avoid, or at least re The ingeniouswheel - ski am- phibious under-carriage. duce, the not inconsiderablecost of sweeping or rolling the snow on an airfield. The intention is to makethe 5A of all-metal construe-
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