RTGModel (Milan Demčišák) released in 2016 his brand new flagship the STRIBOG. This is the successor of the Rotmilan Midi and the latest F3F glider of a family that started with the Extreme, then the Rotmilan followed by a smaller version with the Rotmilan Midi and it features some nice evolutions. According to Wikipedia, "Stribog" is the god and spirit of the winds, sky and air. He is said to be the ancestor (grandfather) of the winds of the eight directions. The Stribog from RTGmodel has a 2.86 m wingspan which is ideally suited for F3F and slope soaring.
What is new?
There are several interesting improvements or modifications that I wanted to highlight below: Wing section is a HN airfoil (Norbert Habe) but different from the Rotmilan Serie. It seems to have higher camber. I don't have unfortunately much detail as manufacturers are generally reluctant to communicate around this topic. The tail section is thinner. Particular flap shape with a smaller flap chord at the root: After exchanging with Milan I understand that the objective with the flap shape was to reduce the turbulence near the fuselage and, as a side effect improve the efficiency of the V-tail. Another advantage is that when down, the flap are not exceeding the bottom of the fuselage, limiting or avoiding damages if you forgot to retract them when touching the ground. Ailerons are running all the way out to the wingtip for better agility and maneuverability. The servos location is very different. Both flap and aileron servos are now very close to each other at the middle of the wing with a single servo cover. My guess for the flap servo location is that the objective was to control the flap at its largest chord.
Full photo album about the kit overview: here
Component weights are the following:
- Left Wing (with servo frames in place): 619gr
- Right Wing (with servo frames in place): 614gr
- Fuselage with canopy: 371 gr
- Left Tail including the joiner: 41gr
- Right Tail including the joiner: 41gr
- Joiner: 84gr
- Total: 1770gr
- Ballast: 895 gr
The fuselage being the same as the Rotmilan, layout is therefore the same. The most difficult operation is the wire routing which need some patience and care to be done properly. Here is how I proceeded: I succeeded to pass 2 x3 wires on each side of the ballast tube. I first prepare the cable on the servos side, with the JR/Futaba connector. Then, from the joiner hole, I used a flexible plastic rod that I passed along the ballast tube up to the nose; I tape 1x 3 wires to it, and pull. Then I repeat the operation 3 times, 2 servo cables on one side, 2 on the other side. Then I can complete the routing to the plug hole and solder the green plug on hit. To maintain the cables in place along the ballast tube, I used some hard foam. A small piece of EPP works fine too.
To secure the 6 pins connectors in place on the root, I prepared first a sort of plug print by using a first part made from 0.8mm plywood crossing the fuselage and a second layer, shorter to create a stop. Doing this, I can then glue firmly the plug which is maintained on every side. I also created a 3D printed template to position the plug well perpendicular to the root while gluing. Before gluing, I protect the wires with some hot gun standard glue, easy to remove, no altering the wire or shrink, and providing a larger surface for the gluing.
Let's return to the wing. You can let the wing servos connectors free, or glue them in place. I prefer the second method even if it requires some attention to not glue everything in place. To do this, I protect the root of the wing and the fuselage with thin tape, put some polyvinyl alcohol release agent where needed on the fuselage plug, connect the wing plug on it and it on the wing side with the wing in place. This gives a perfect alignment.
Full assembly log photo album : here
At the slope
The maiden flight was in Ardèche on a nice cliff but in light conditions. Everything went well and I immediately felt that the Stribog was very different from its predecessors. When the Rotmilans were naturally fast but were lacking a bit of grip in turns, especially in light conditions, the Stribog is clearly keeping the fast straight speed, but adds lots of grip in turn, and a very good agility.
And the Stribog continue to perform when the wind and the lift is growing, and is not disturbed by strong wind. By adding two tungsten slugs in the joiner, I could go to 1.400 kg of ballast, and the Stribog was still happy and continued to deliver.
Rapidly, I was confident enough to decide to engage the plane in the battle and use it during the summer in my preparation of the world championship, achieving my personal best, still in Ardéche on the same cliff, with a 26.21s. I also used it as my backup plane during the FAI/world cup contest of Col de Tende, doing the last 4 rounds with it, and winning this competition against some of the best F3F pilots. Then, in August, I used it in a league competition and won this competition.
Overall, the Stribog desmonstrated to be very competitive and at the level of other popular competition planes. I'm very pleased with the progress made on the performances in flight.
"Flying the Stribog" Photo album : here
In brief the Stribog is a real step forward compared to the Rotmilan and Rotmilan Midi. It keeps the best of the Rotmilan, the straight speed, and brings now the agility and grip in turns. On the market, the Stribog is a very affordable and a very competitive F3F plane, with a superb molding quality.
Nothing is better than few videos to illustrate what I wrote. I propose you the video of the maiden flight, one showing a 29 and a 30s flight during French team practice this summer, but the first one is a more edited video with some onboard and slow motion sequences.
- wingspan 2867 mm
- Fuselage length 1463 mm
- Airfoil HN Straak
- Elevator airfoil HN modif.
- wing area: 55,2 dm2
- projected tailplane area: 5,7dm2
- Empty flying weight: 2320 gr
- Manufacturer website : RTGModel
|Elevator||7||mm UP||7||mm DOWN|
|Rudder||9||mm UP||9||mm DOWN|
|Ailerons||Flaps||15||mm UP||10||mm DOWN|
|Ailerons||25||mm UP||15||mm DOWN|