Design
When you first pick up a product from a company that has just entered the market, you always have some misgivings about the quality of workmanship. But in the case of the Rhythm, you can relax. Yes, the design looks quite modest - it's not Edwards or Jean. But there are no complaints about the quality of cut and sewing. We could not find any hand-marked parts on the wing, which means that the production is most likely done by plotter, and the very accurate cut lines prove it. The seams and terminations are also quite neat. I wouldn't be surprised if it turns out that the Rhythm came from under the same sewing machines that sew the legendary Gins. In any case, the technologists and manufacturers of DaVinci earn their rice and soy sauce honestly, there's not much to complain about.
Some sense of artisanalism is caused except by the loose ends. No, there is nothing wrong with them, but they are arranged very simply, without any frills, like the ends of domestic producers of the second or third echelon. Pretty wide band (22mm), very average quality Brummel hooks, simple bearingless blocks in the gas pedal wiring... Only decorative patches with producer's logo and neat swivels with swivels speak about some ambitions of Korean manufacturer. The prototype has surprisingly few slings: A2A'1B4C3. This is not necessary for a training wing. The choice of materials does not disappoint: quite thick and durable Dokdo articles, thick braided slings. You can see that this is a workhorse, not a fluttering sports-record machine. The same can be said about the shape of the wing. It is modest, neat, low elongation, huge intakes. The coloring, for my taste, is a little garish - but to a taste and color...
Takeoff, wing work on the ground
Classic! The rhythm is pretty much how a beginner's wing should work. Ascending to take-off is unhurried, a bit wobbly, but very reliable. There is no need to "pull" the wing with forward rows or, on the contrary, to "suffocate" it, pre-empting the flight. It is enough to pull something and in two seconds rhythm will be in flight position. Unfortunately, the weather did not let me do any ground handling training, but I had to test the wing in severe conditions - launching from a restricted landing strip in a slanting gusty wind or in no wind. And Rhythm did not disappoint, always reliable and confidently entering the flight position.
Flyability. I think the epigraph of this test drive is eloquent enough in itself. But we're talking about the most training, "beginner" wing here, so it's okay. And in some cases, it's not bad at all. In a straight line flight at balanced speed Rhythm doesn't noticeably loses to almost-beginner Ozone Buzz Z5 - if you arm yourself with a cocoon and try to pilot as gently as possible. But any maneuver that involves deviating from a straight line flight results in a clear and very noticeable increase in rate of descent and glide drop. In part, this is also due to the shape of the Rhythm polar. Like on much older wings, the balancing mode and minimal sinking mode on the rhythm are noticeably spaced apart - at least by several kilometers per hour and by at least 20 centimeters of brake travel. This is why you have to really push the boat hard when steaming and attempts to work in thermals with small brake strokes do not lead to anything good. Similar behavior is typical for speedgliders and mini-wings, but with the Rhythm all speeds are noticeably slower, which makes life a lot easier.
Flying on the gas pedal. The Rythm has a gas pedal and it works. That's pretty much all a pilot needs to know about the gas pedal on this wing. To be a little more specific, the serious drop in aerodynamic quality from the first centimeters of gas pedal travel makes it almost impossible to use the gas pedal otherwise than to accelerate the already pretty fast approach to the ground. Well, or for learning to fly on the gas pedal. More precisely, to get used to some of the characteristic effects that occur, such as a slight increase in the sharpness of wing roll and pitch. I could not measure the speed increase - I did not have enough time for reliable averaging in any flight, the altitude ended too quickly. My feeling is that the speed increase is quite normal for EN A, something like 10 km/h. What is curious, on the gas pedal the device is perfectly controlled by the rear rows, not at all worse than the devices of a couple of classes above.
Controllability. Here everything becomes interesting. On the one hand, it doesn't really react to small brake movements (5-10 cm), which is actually normal and even good for a frankly educational dubolo... excuse me, wing. On the other hand, if you pretend to be a dummy and start swinging your arms to the fullest - then you get pretty sane and even somewhat pleasant controllability from the Rhythm. In combination with already mentioned above features of the polar, it means that to fly in the thermals on the Rhythm you need a good old style of piloting, which appeared long before the modern "don't let the wing fly". You shouldn't interfere with it either. You have to help it, and help it very energetically. Maximum weight on one side of the harness, both levers till the carabiners, inner hand 10-15 cm down and you get quite decent, compact turn. With so much clamped brakes Rythm responds to the work of the hands quite sane, allowing you to change the radius of the helix and the intensity of rotation quite quickly. Even more interesting is that at quite big brake strokes (approx. 70-80%) rhythm doesn't get too sharp and doesn't tend to jerk, it just looses a lot in quality. It's a good idea for a precision rider!
The behavior at low speeds in the case of the Rythm is worthy of a separate chapter in the test-drive. It looks like this machine was created, first of all, for flying at low speeds. It's been a long time since I've seen such sane, simple and clear behavior in the left part of the polar. It's possible to crash rhythm - full brake travel is very big, but it doesn't exceed physiological possibilities of a typical pilot. This also applies to hand travel and load on hands near stall. At around 50% brake travel the drop in performance becomes very noticeable and then glide decreases without any vibrations, localized stall on portions of the wingspan and other effects which are typical for longer gliders. Around 70-80% of brake travel the Rhythm simply flies very slowly, smoothly and with very low aerodynamic quality while maintaining a decent handling. Even at long brake strokes the control does not become too keen, the glider forgives even quite noticeable piloting errors, but it is surprisingly easy to control the planning angle. Turn and yaw errors are no less easy to correct - the effectiveness of tightly closed brakes is just enough to do this. As a result, you can safely go over the target with exceeding it by a couple meters - at the end of the approach the excess altitude can be easily removed by firmly pressing the brakes and smoothly "waking up" down. "The dumbfounded nature of the Rhythm helps a lot when landing for precision in turbulence - it is not easy for the boiling ground air to dislodge the Rhythm from the trajectory set by the pilot.
Comfort and informativeness. No, it's not a trunk, it's a tank of some kind! It's clear that a device with such a modest elongation simply can't be sharp and uncomfortable - but Rhythm also has long lines in its forehead, which provide this product of Korean paraprom with remarkable resistance to collapses. It's interesting that Ritm is very eager to rustle and crunch the cloth, warning about the changes of loads on different parts of the wing - but all this rustling and crunching in practice mean almost nothing for the pilot, because it's very difficult to get real "fight" collapse on Ritm. At dangerously small angles of attack the lines willingly take the load on themselves, and the Rhythm comes out of tense situations with honor. Rustling and crunching are not very useful from the point of view of finding and centering streams. Rhythm's informativeness is primarily changes in airspeed and, to a somewhat lesser extent, changes in arm loads, and very little useful information comes to the suspension. As a low-elongation wing should, the Rhythm has no tendency to "flap its ears" and behaves very "monolithically" even in quite strong turbulence. Roll and pitch damping are at a high level even for EN A, though it has its own features. When you drop out of the flow, the Rhythm tends to unexpectedly veer sharply forward with the outer bracket, which you should hold in place with the brake. But you don't have to do this - it won't work anyway.
Dynamics and power capacity. Normal average level for a school-practice wing. If the pilot tries hard and knows exactly what to do, he can get vingovers and power spirals from the Rythm, but if he doesn't ask the wing for it very clearly and persistently.but if you don't ask it very clearly and persistently, it will do its best to keep you from making drastic trajectory changes and unpleasant roll and pitch motions.
Dangerous flight modes
Asymmetric folding
Great. It is physically quite difficult to extend, as the input force is quite high. The wing breaks around 20-25% of the chord, but some powerful wires at the leading edge just don't let it grow. You get a kind of "undercompensation", which when you release the A-row opens instantly and almost does not lead to changes in the trajectory. Similar behavior can be observed with the Skywalk Cayenne 5, which also has very powerful lines in the leading edge.
Thermal spiral blowout
Great. Surprisingly, this mode gets triggered in a training wing (perhaps the "precision" specificity of the Rhythm affects it). The mode develops smoothly, predictably and unhurriedly, giving the pilot time to realize and correct his mistake. The exit slope is 20 degrees, and it is no problem to remain in the thermal spiral after exit from the underrun.
Conclusions
The Rhythm is a very specific device, designed to solve a narrow range of tasks. But it solves those problems well, maybe even perfectly. Impressive damping on all axes and very calm reactions to steering and bumping are very good for the initial training and fine tuning. Low maximum quality and smooth glide reduction on the left side of the polar - the fine-tuners will be just happy. But for hovering, and especially for cross-country flights, our glider is not very suitable, even for EN A class - there are more "flying" and "hovering" wings. However, in Russia high flying characteristics of the EN A class are not really required, but high safety and an ability to hit the target precisely even in difficult conditions - on the contrary, they are very attractive for flying schools and for spotters. The overall behavior of the Rhythm resembles an overgrown mini-wing: a modest elongation, a specific polar, an unexpected and pleasant ability to make a compact turn on strongly clamped brakes... but all this at much lower speeds than mini-wings, and, accordingly, more easily and safely. You can't fly far away on the Ritm, but you can almost fit it into a supermarket parking lot on a sale day!
The minimum flying time required... Usually this is a very difficult question, but not in the case of Rhythm. It is with great pleasure and a feeling of complete confidence that I write the word "zero". Yes, even an inadequate novice pilot can be safely trusted with this machine - and Rhythm will most likely do him no harm. Of course Rhythm is a very good option for initial training that for some reason has to be done in difficult conditions (limited launch and landing, presence of turbulence, etc.). It is also possible to consider the Rhythm as a mountain launcher - but in this case it is desirable to overload it by 10 kilograms to have some reserve of speed.
Pros of
- High passive safety
- Relaxed character
- Highly resistant to folding
- Ability to perform compact thermal turns
- Expressed drop in quality on the left side of the polar, ability to fly comfortably and controllably at very low speed with very low quality
Cons
- Not the highest flight performance
My thanks to Davinci Gliders and its Russian dealer Rinat Sabitov ( http://altair-aero.ru/ ) for providing the glider for the tests.
Photo: I. Tarasova, A. Tarasov.