Wing:
The mid-wing glider's cantilever wing had a rectangular planform. The flaps were placed on the trailing edge between the wing-roots and the inner end of the ailerons. The settings of the flaps were 5 degrees for winch-launching and 60 degrees for landing. The wing had a wooden structure with one main spar and an additional diagonal steel-tube spar at the root. In the wing uniform rib-structures were used as the wing section was constant on nearly the whole span. The ribs of the ailerons, flaps, elevator and rudder were made of thin duraluminium sheets fastened to a single light-metal tube spar. The wing in front of the main spar was covered by plywood. All the other part of the wing as well as the ailerons and flaps were fabric covered.
The fittings of the wing connection were formed such a way that it was possible to fold the half wings alongside the fuselage, however beforehand the horizontal tail surfaces had to be folded up.
The R-15b Koma was safe of unintentional spinning. Even it was practically impossible to spin it intentionally due to the gradually increasing gaps between the wing and the leading edge of the ailerons.
Fuselage:
The fuselage consisted of two parts. The fore part was a closed, streamlined wooden structure the lower part of which was covered by plywood, the upper part by fabric. The aft part of the fuselage was a plywood covered wooden beam with small cross section. This beam was braced by two cables on both sides to the wing. The landing gear consisted of a fixed wheel located behind the c.g., a rubber dumped skid under the fore part of the fuselage, and a small skid under the vertical stabilizer. The wings were protected by curved steel-tube skids located under the wing tips.
The side-by-side seats were covered with a two-part streamlined plexiglas canopy. The two parts opened sideways in the direction of the centerline. The small instrument panel contained only a speedometer, an altimeter and a variometer.
Tail unit:
The tail unit had traditional arrangement. The ribs of the elevator and rudder were made of thin duraluminium sheets fastened to a single light-metal tube spar. The horizontal and vertical stabilizers were covered by plywood. The horizontal stabilizer were strutted and foldable.
The first prototype, R-15 Koma
Dimensions: |
Wing: |
Span, m: |
14 (corrected) |
Area, m2: |
18,04 |
Aspect ratio: |
10,84 |
Chord (root), m: |
1,3 |
Chord (tip), m: |
1,0 |
Airfoil (root), m: |
Gö 549 |
Airfoil (mid-span), m: |
Gö 549 |
Airfoil (tip), m: |
Gö 549 |
Dihedral, degree: |
3 |
Sweep, degree: |
0 |
Washout: |
None |
Aileron: |
Span, m: |
3,6 |
Mean chord, m: |
0,514 |
Total area, m2: |
2,26 |
Balancing: |
None |
Flap: |
Type: |
Plain |
Area, m2: |
1,84 |
Relative length, %: |
39,2 |
Movement (up/down), degree: |
15/60 |
Airbrakes: |
Type: |
None |
Horizontal stabilizer: |
Span, m: |
2,44 |
Area, m2: |
2,56 |
Elevator: |
Span, m: |
2,56 |
Area, m2: |
1,1 |
Airfoil: |
Special |
Balancing: |
None |
Trim: |
Yes |
Vertical stabilizer and rudder: |
Total area, m2: |
1,604 |
Rudder area, m2: |
0,771 |
Balancing: |
None |
Fuselage: |
Length, m: |
7,0 |
Width, m: |
0,937 |
Height: |
1,12 |
Cross section, m2: |
0,78 |
Landing gear: |
Type: |
Fixed |
Wheel diameter, m: |
0,26 |
Masses: |
Wing, kg: |
106 |
Fuselage, kg: |
73 |
Tail unit, kg: |
6 |
Empty glider, kg: |
185 |
Gross, kg: |
340 |
Ballast, kg: |
None |
Wing loading, kg/m2: |
18,85 |
Speeds: |
VNE, km/h: |
130 |
Max. speed with flaps extended to 60 degrees, km/h: |
85 |
Max. aerotow speed, km/h: |
80 |
Max. winch speed, km/h: |
80 |
Max. speed in rough air, km/h: |
80 |
Stall speed, km/h: |
56 |
Performance: |
Min. sink, m/s (at gliding speed, km/h): |
1,05/63 |
Best L/D (at gliding speed, km/h): |
17,4/70 |
Start methods: |
Winch, Aerotow |

Origin of data and 3-view drawing:
Jereb Gábor: Magyar vitorlázó repülőgépek, Műszaki Könyvkiadó, 1988, Budapest
(Gábor JEREB: Hungarian Gliders, Technical Publishing House, 1988, Budapest)
Gábor FEKECS E-mail: fekecs.gabor@t-online.hu