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Yuriy Yatsenko "Classic" control line F2B demountable model

Model: "Classic"
Сreator/Manufacturer: Yuriy Yatsenko
Weight: 1600±20 g
Engine: Discovery Retro 60, 10 cc

F2B - Classic model of Yuriy Yatsenko Yuriy Yatsenko Classic model scheme


"Classic"

The model created in 1992

Model of Yuriy Yatsenko, that was called “Classic”. Classic because it was made as the attempt to construct the model that joined classic model design with the best traditions of the control line abilities, that was got from studying of the best examples of function that time sport models , also from accessible literature and communication. The first models had vertical engine location, then it was changed to horizontal position, as more useful for more symmetric engine work. There were also attempts to install the engine to the position 30 deg. cylinder down from horizontal. Short history of the way to this model creating may be interesting for builders because we all know (who do not know, believe us), that it is impossible to calculate the model, the only way is to accumulate the experience from various models building, and step by step moving to the “gold middle”, to the model that can fly, as you feel, it must fly in your dream. In this way, the most important thing is not to go the wrong way or too far. I know a lot of talented people who spent a lot of time and efforts to the bright experiments. But it was so far from the “gold middle” that it was only loss of time, and the understanding of a long way from that point did not allow these people to finish the research works and to come to the good result. Be careful with the time.
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The first large model of author was built in 1974 from the drawing of the Soviet Union Champion Evgeniy Petrov. The example of the highest aesthetic view, this model had unique flying capacities and many new design working outs, like ball locks for the main landing gear (designed and used by Petrov the first time). This model drawing was designed on the base of drawing of  Evgenoy Kondratenko models (3rg place in tha WCh 1961), more correct, his pupil drawing, master of model building and famous sportsmen Viktor Kramskih.

Kondratenko modelKondratenko model

Kramskih 5.6cc model

( I add the drawings of all called models). I was lucky. This first big model had very good flying capacities. The first success is very important for the feeling that you are on the correct way.

Evgeniy Petrov 7cc model

3 next models was the experiments with the building of modified models of famous Soviet pilots, Anatoliy Kolesnikov and Alexander Listopad.

Anatoliy Kolesnikov with KA-5 model
Anatoliy Kolesnikov KA-5 model scheme with 5.6cc engine
Anatoliy Kolesnikov model KA-5 with 5.6 cc engine
 
Kolesnikov KA-8 model photo
Anatoliy Kolesnikov KA-8 model scheme with 7.5cc engine
Most famous Anatoliy Kolesnikov model KA-8 with 7.5 cc engine
 
Anatoliy Kolesnikov model KA-10 with 10cc engine
Anatoliy Kolesnikov model KA-10 with 10cc engine
 
Aleksandr Listopad
Aleksandr Listopad 7cc model
Aleksandr Listopad 7cc model

In 80th author had created some models on the base of American publications.
Famous American Stiletto, Exitation, Genesis, Eclipse had gave the inf. for the first experimental models, like showed on the picture. It was the base of the experience for the next own model creating.

GENESIS model scheme

From my first models, where was got the airfoils from the catalog of the aerodynamic airfoils, I had come with the understanding, that catalog airfoils are not good for the aerobatic models. It was very sensitive  to the turbulent air and get a lot of energy for the model turn (as loosing the speed after the sharp turning).

The successful airfoil was found from the talk with Anatoliy Kolesnikov. To the question, why his last wing airfoil have  visible  small radius on the leading edge (KA-8 model), it was answer, that the first models had large radius edge,  but it was difficult 1 lap gliding before the landing, and was not enough sharp in the air. With the sharp edge  the gliding ability become better. Also he said that one line location of the engine-wing-stabilizer creates the feeling of symmetric model control. And he had real feeling, that with this model he do not need so many training for good result, as with his old model, not one line. Seeing very stability flights of Anatoliys models, I had tried to create something new. According to my understanding of the airfoil configuration from the experience and this talk, I had created the airfoil that was found as very successful.  Models become to fly stability in wind and it was feeling of easy turning, with good stability then. First airfoil had the thickness 56 mm, then was modified to 64 mm thickness, more stability for turbulent air.

About one line models. I had start to build only one line models. And I understand, that it is correct way, when I had flown on famous Luchiano Compostella model with 4-stroke "Webra". As tradition, Luchiano's models have very low wing location and up stabilizer, this model was the European Champion. It was very interesting for me, how the champion's model flies. 

Compostella model photo
Compostella model scheme
Luchiano Compostella model with 4-stroke engine Webra T4-60 (10 cc)

I was very impressed of horizontal stability of the model flight, on inverted flight after the turning the model had absolute perfect stability. Sharp corners, that every time impress me from the old school pilots, as Luchiano. Just one thing in the model flight, that I had found not convenient. I understand, that I can not stabilize the model after the turning on square normal figures. Model every time try to make the wave after the turning. All my efforts to make correct figure was not success. My  sincere respect to Luchiano, who had the European Champion with this model, as to greatest pilot. It was need a lot of training to have this result.

But I understand the difference between the one-line scheme and the tradition old scheme. It is very correct inverted figures, and  problematic normal figures. I explain this as the wing close the stabilizer on the large angles of attack in normal figures. Thanks to the large distance between the wing and the stabilizer axis, this feelings was very bright on Luchiano's model.

That is why I like to test various models, every this flight it is the concentrate experience of the way of the person, who had made this model.
Small distance between the wing-stabilizer axis are not so visible in the control feeling. But no good to make very large distance, as I understand. 
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The prototype “Classic” was the model “Sigma”, used in 1992 WCh in Gradets Cralove. The first time was used “Discovery Retro” engine.

Sigma model photo
Sigma model scheme
"Sigma", my first one line demountable classic design model with the first 9cc "Discovery Retro" engine.

Next year was born the first “Classic”. The model was so successful, that without visible modifications it lives to the present days. Stability horizontal flight together with ability of sharp turning and possibility to stabilize the model very easy.
The result was so good because it was find the balance between all control surfaces area, and the position of stabilizer according to the wing place. Also very important, minimum moment of the model around the wing axis ( by another words, it is light nose and tail).
Now I will try to show the formula of success CL aerobatic model, that was find as result of building and using and tests of many planes:

1. Zero wing, stabilizer, engine angle position according to the horizontal model axis.
2. Symmetric airfoil of the wing, stabilizer (it means maximum possible symmetric that you can make, including the control surfaces mounting and contour).
3. Most minimum moment according to the wing axis.
4. Most easy moving of  all control system.
5. Harmony balance between the wing and stabilizer area, together with the distance between wing and stabilizer, and the area of flaps and the elevator, their angles of turning.

(important for the creators of the new model scheme).

If you will loose just one from showed characteristics, you will loose the flying capacity of the model.
If you want to build your model from the drawing of any successful or famous model, you must remember: if you will make this model according to the called points, it will fly perfect. May be even better, than prototype, if you will improve one or some of this characteristics.
But if you will not pay attention to this rules, probably you will be surprised by not good model flying. Probably you will explain this to yourself, that the prototype is not good.  But  really, it is just because you do not know, or do not pay attention to the main rules of CL aerobatic model building.

Now step by step, how to build the model according to showed rules:

1. To install all surfaces and the engine "zero" is possible, if you have absolute straight plane for assembling (the table with very straight surface). With simple tools it is possible to fix all model surfaces straight according to this base surface. You must control the surface and be sure that it is straight. Curved and twisted base plane will give the mistakes, that will act to the model flight.

2. Symmetric airfoil,how to make this? According to the construction of your model, step by step it is need to keep the dimensions of the airfoil. From the first step, the accurate making of the ribs templates, to the quality of covering, when the soft cover between ribs have symmetric curve on up and down surfaces of the wing.
Important to install flaps and the elevators to the axis of the wing (stabilizer). If it fixed upper or down, you receive not symmetric airfoil. This model flight will be not logic.

3. Minimum moment around the wing axis it means, that it must be very light nose and the tail. For this, better to start the model building from the stabilizer. If your built stabilizer is heavy, better do not use it for the model building, better to write off it to fighting looses, and to the experience accumulation. Using this experience, build the next, the next, until you will receive the waiting result. According to the weight of the stabilizer, and the engine weight, you select the nose length. Important to make this correct. Because if you will be mistaken, the center of gravity will be not on the place, you will be compelled to trim it by the weight, putting to the nose or to the tail. It is bad both, because it increase the called moment.

It is obviously, that better to select the light engine, than heavy. With heavy engine the nose must be shorter, also the total model weight will be higher. Both things are not good for the model.

Short nose model have not correct balance of the nose and tail area of the fuselage. Like weather vane, the model tries to turn the nose against the wind. Sometimes it is danger for the stability of the lines tension.
For minimum moment and weight of "Classic" was find the method of production in mould. The advantage of this method is the economy of the weight of the finishing surface layer.

Tradition way is to cover the balsa by paper with farther painting by some layers of paint, with intermediary finishing of every layer (nice but heavy finishing). Or cover by Oracover or another special covering films (not nice).
Painting the mould and receiving the good surface ready, give the advantage of the control of the finish surface weight. I do not find the possibility to have so good outside view with so minimum weight. It is the main advantage of the moulded models.Plus very good stability geometry, got from the mould.

One more word about the moments. It is the gyroscopic moment of the propeller. The best if the prop have no weight. It is impossible, that is why the prop must have the minimum weight. I had tried many kind of props, it was found that the wooden is the best as most light. From heavy plastic props the model twist the trajectory in the air, change the wing position according to the lines line, especial with more sharp turnings. Heavier prop, more RPM -  more action.
To understand the force, that acts to the model, it is easy of you will try to turn the axis of rotating bicycle wheel, if you keep this axis in your hands. You will be impressed.

4. Easy moving of the control system is possible to make, if you control all moving elements according to this aim. Every element. Better to use the friction pairs metal - plastic (Nylon), it is not need the greasing, and have minimum coefficient of friction. Also it is very long life and light weight.
Better to have limited shaking in the control elements, than hard control system moving. Our model is aerobatic, control system must be absolute perfect. To fly with hard control system is the same, as to drive the car with hard control wheel, all trees are your's. The same as hard control system increase the gravity action to the model, its possibility to "meet" the land many times higher.

How to control? When the model  is on the land, and you move the handle, you must not feel any friction. It reaches by every friction control system  element trimming during the assembly.
The weight of the control system is very important too. Inertia of very fast moving push rods makes the action of the control system more slow. It is not pleasure feeling, when the model is late for the handle moving. The same about the flaps and elevator weight. Minimum weight- minimum inertia. Faster model reaction.

5. You feel needs to create the new model of your construction.
Usually not very experienced designer gets as the example the drawing of famous or good model, and tries to modify it by changing of some dimensions.

For example , you want to have more stability and maneuverable model, than the prototype. You propose correct, that it is possible to do, if to increase the distance between the wing and the stabilizer. You correct this dimension and build the model.
Even if you will make all details according to the showed in the notes weight, probably you will not receive the waiting result. Because you did not think about the balance of the model. In wide understanding.
Every good flying model is good balanced. If you move the stabilizer farther from the wing, you change not only the aerodynamic moment of it, but move its mass too. So, you must understand, that you move the center of gravity back. Yes, the maneuverable will be higher with this stabilizer position, plus back center of gravity. But you loose the stability, the model is more sensitive in horizontal flight.

You loose the model total balance.
What you do when you understand this? You move the center of gravity forward, put the weight to the nose. But model do not want to fly better, it makes valve after the sharp turning. What happen? The balance stay lost. The moment of the model around the wing axis is higher, because the nose and the tail are made heavier. Plus the model is heavier to the weight of nose load.
For example, you is more experienced designer, and you understand, that you must save the position of the center of gravity. You move the stabilizer back, but increase the nose length, compensate the tail moment. It is clever and logic decision. However, you can not receive the waiting result again. Because you have the same higher moment around the wing axis, as before, only better situation, that there is no extra weight in the nose.

So, you start to understand at last, that if you change the stabilizer position, and want to save the model balance, it is need to save the center of gravity together with the moment around the wing axis. For this it is need to find the possibility to make the stabilizer lighter, according to distance, that you move it.

Is this all, as you think? No. We forget about the balance between the flaps and the elevator. Flaps moment and the elevator moment acts to various directions. If you increase the moment of the elevator, the moment of the flaps is the same now. So, you increase the effect of stabilizer many times more, than you had think. It acts to the possibility of the model stability after the sharp corners. To return the balance back is possible , if to make the flaps area bigger. Or to increase the flaps turning against to the elevator turning.

O.K., we have changed the flaps area. Or its turning. Possible, it will be need to increase the engine power, because the model needs now more energy for sharp turning, do not loose the speed.
You change the engine to more powerful. As rule, it is heavier. Again we are before the question of the position of the center of gravity and the moment of the model. Together, we have the question of the model total weight. But heavier model needs larger wing area… And so on, and so on.

I show this look like not difficult example of the model modification for showing, that not so easy to design the new model even from the prototype drawing. This 5th rule is important together with the showed before 4 rules of successful model.
I have showed only the characteristics, that is most visible. But there are many another things, that I did not show here. It have action to the model flight too, and you must know this. Its action one to another is so complex… If you design the model, and think, that may be you will be so successful , that without any knowledge and the experience you will draw now the best model…

The possibility of this is the same, as if you shoot to the sky with closed eyes think, that you will get the small bird, that flies some where high in this sky.

Literature, communication with experienced people, experiments with models, step by step you will move to the understanding of the model flight and the design.
If you feel the designer talent.
If no, better to build the famous model that you like. In the best condition, according to the rules of success.

Success

Yuriy Yatsenko

Painting

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