About this Plan
Akro-Baby. Radio control sport aerobatic model. Wingspan 1050 mm, for 2.5 cc engines.
Quote (google-translated from the German): "A model with simple lines, yet beautiful and appealing in its shape, easy to build with little material expenditure and fully aerobatic - that was the goal when constructing the Akro-Baby. All these properties can be certified after extensive testing of the model.
The construction time is approx 14 days with normal 'after-work work', the required amount of wood is small, mainly because the usual wing planking is not necessary. The strength of the wing is sufficient for all aerobatic maneuvers and the associated loads. Thanks to the simplicity of the model, the building instructions can be kept very brief.
Fuselage: The side walls are made of 3 mm balsa, the front and rear area reinforced with 0.8 mm plywood provided with round recesses. Strengthening parts (doublers) are marked with small black triangles on the blueprint. The plywood frames and the engine mount are glued in between the finished side walls (parts 1-5). The fuselage top is made of 3 mm balsa, the bottom is 2 mm balsa.
Undercarriage: We bend the legs in two parts from 4 mm steel wire. The landing gear mount in the fuselage is made of 4 mm plywood. The landing gear is first pushed into the finished and painted or covered fuselage and fastened with two small screwed aluminum clamps. We tie the skid made of 1.5 mm steel wire to a piece of pine strip, resin it with two-component glue and glue it into the fuselage.
Tail unit: The elevator and vertical tail are made of balsa strips 5 x 10.5, 5 x 5 and 5 x 15 mm, the elevator is in the middle with 5 x 5 mm jaw reinforced. We sand the rudder in profile from small balsa sheets with a thickness of 5 mm. Small light nylon hinges serve as a suspension.
Wing: We need hard 5 x 20 mm balsa for the spar, 10 x 10 mm balsa for the leading edge and 7 x 10 mm balsa for the trailing edge. We manufacture the ribs as a block of 3 mm balsa. The wing center piece is planked on both sides with 0.8 mm plywood. From 3 mm plywood we saw the wing connectors that give the wing the V-shape. We sand the strip ailerons from balsa 30 x 10 mm, for the linkage we use a finished part or we bend it from 2 mm steel wire. We cut and sand the edge arches of the wing out of 10 mm balsa.
Engine: With a 2.5cc engine, the Akro-Baby is well powered. In order to achieve the correct center of gravity without any trimming lead, it is advisable to place the battery as far forward as possible. But then the tank must be installed above the battery. The tank is pushed with its cap into the recess of frame 2 and fastened in the corresponding recess in frame 3. All connections are accessible from the engine compartment.
Finish: In its simplest form, the model can be covered with film most quickly. Paper covering of the model, or paper covering for the fuselage and artificial silk for the wings is of course also possible.
Flying: After the model has been adjusted (downthrust 0°, side thrust 2°, wing incidence 0°, EWD 0°) we can take off for the first flight. The model launches from the ground without any problems, hand launching is safer if the grass is too high. Thanks to the 0° adjustment angle difference, the acro baby behaves absolutely neutrally in all flight maneuvers.
For less experienced pilots it is advisable to adjust the wing incidence to 0.5 to 1°, this makes the model slower and much more inherently stable. After you have the Akro-Baby well under control, you can increase the setting angle difference to 0° and then get out of the model what's in it: A lively, agile, fast plane - an aAkro-Baby."
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Supplementary file notes
Article, in German.
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User commentsHi there, attached are some photos of the Akrobaby [main pic, 008-012]. The orange one is powered by a O.S 20 FS and the yellow one by a O.S 15 FP. They fly very nice. Thank you very much, Gustavo From Brazil
Gustavo Delazaro - 05/07/2022
Hi Outerzone, Another model built from your plan! The Akro Baby [pic 013]. Not yet finished but soon. Best Regards,
Erick Baccus - 03/12/2022
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