Davinci Rhythm: born to land

DaVinci is a brand new Korean paragliding brand. Let's try their glider for school and accuracy: the Rhythm.

Design


When the first time you pick up a product of a company just entering the market - there is always some concern about the quality of the workmanship. But in the case of Rhythm you can relax. Yes, the design looks rather modest - it's not Advance or Gin. But there is not the slightest claim to the quality of cut and tailoring. It was not possible to find the hand made markings on the wing - it means that the cut is very likely to be made by plotter, which is confirmed by very neat cut lines. Stitches and seals are also quite neat. I won't be surprised if it will turn out that Rhythm came out from under the same sewing machines, on which the legendary Gin are sewn. In any case, DaVinci's technologists and production workers honestly earn their rice with soy sauce, there's nothing to complain about.

Only the risers culd deserve some improvement. No, they are all right - but they are of a very simple make, without any frills, just like the second-third echelon brands do. The webbing is pretty wide (22 mm), the quality of Brummel hooks is very average, the pulleys of speed system have no bearings... The only sign of certain ambition of the Korean manufacturer are the decorative stripes with the manufacturer's logo and accurate brakes with swivels. The lineset is surprisingly minimalistic: A2A'1B4C3. A three-row, which, in principle, is not necessary for the entry-level wing. The choice of materials does not disappoint: the thick and durable Dokdo cloth, thick sheated lines. It can be clearly seen that Rhythm is a workhorse, not a competition-winning "gun" . The same can be said for the shape of the wing. Modest, neat, low aspect ratio, large cell openings. The coloring, for my taste, is a bit lurid - but it's rather a question of personal perception.

Take-off and ground handling

Classics! The Rhythm behaves exactly as it should behave. Inflation and rise up to the flight position is a leisurely, but very reliable. There is no need to "pull out" the wing with A-risers or, conversely, "slow down" it, preventing the overshoot. It is enough to somehow pull something - and after a couple of seconds, Rhythm will always be in flight position. Unfortunately, the weather did not allow me to practice ground handling with all my heart, but I had to master the wing in quite "combat" conditions - when starting from a limited area in a oblique gusty wind or almost at complete calm. And Rhythm did not disappoint, always safely and confidently going into flight position.

Performance

We are talking about the very fact that there is the enty level, "novice" wing, so everything is fine. And in some cases - even not bad. In a direct flight at trim speed, the Rhythm does not noticeably lose to the almost-training Ozone Buzz Z5 - provided that you arm yourself with a cocoon and try to fly as gently as possible. But any turn maneuver leads to a clear and very noticeable increase in the sink rate and drop of the glide. This is partly due to the shape of the Rhythm's polar curve. Like the much older wings, the trim regime and the minimum sink regime for Rhythm are quite noticeably spaced - at least several kilometers per hour and not less than 20 centimeters of the stroke of the brakes. Therefore, when you are climbing in thermals, you have to "slow down" the device quite strongly, and attempts to work in thermals with small strokes of the brake do not lead to anything good. Similar behavior is typical for speed gliders and mini-wings, but Rhythm's speeds are noticeably smaller, which greatly simplifies the flying.

Flight at bar

The Rhythm has a speed bar and it works. In practice, this is all that a pilot needs to know about the speed system of our examminee. In fact, there's a serious drop in glide from the very first centimeters of the speed bar travel which practically does not allow using the accelerator differently than to accelerate an already fast approach to the ground. Well, or just to train the accelerated flight. More precisely, Rhuthm is good for getting used to some of the characteristic effects that arise in accelerated flight, for example, to a slight increase in the sharpness of the wing movements along the roll and pitch. I could not measure the speed increase - in every flight I did not have enough time for reliable averaging, the altitude was wasted too quickly. On subjective sensations, the speed gain is quite normal for EN A, something about 10 km/h. Interestingly, while flying at bar, the glider is perfectly controlled by the rear rows, not at all worse than the gliders by a pair of classes above.

Handling

Here everything becomes interesting. On the one hand, for small moves the brakes (within 5-10 cm) Rhythm does not react almost in any way, which, in principle, is normal and even good for an aentry level wing. On the other hand, if you pretend to be a newbie and start pushing the breakes really hard - then Rhythm appears quite sane and even something pleasantly manageable. In combination with the above-mentioned features of the polar curve all this means that for thermalling on the Rhythm you need the good old style of piloting that arose long before the modern "do not prevent the wing from flying". Rhythm needs help to soar, and it should be a very vigorous help. Weight to the maximum on one side of the harness, both brakes to the carabiners, the inner hand another 10-15 centimeters down - and the Rhythm reveals a quite decent, compact thermal turn. On such strongly clamped brakes, the Rhythm responds to the extra brake input quite well, allowing a fairly quick change in the radius of the spiral and the intensity of rotation. Even more interesting is the fact that at very large brake strokes (about 70-80%) the Rhythm does not become too sharp and does not tend to go into parachuting, but simply loses the glide. Perfect for precision landing!

The behavior of Rhythm at low speeds is generally worthy of taking out in a separate chapter. It seems that this glider was created primarily for flying at low speeds. For a long time I have not met a paraglider with such a sane, simple and understandable behavior in the left part of the polar. It is quite possible to stall the Rhythm - the full course of the brake is very large, but does not go beyond the physiological capabilities of a typical pilot. This applies both to the brake travel, and the brake loading near the stall. Somewhere after 50% of the brake stroke, the drop in glide becomes very noticeable, and further the glide smoothly decreases without the appearance of vibrations, local stalls on the part of the span and other effects characteristic for wings with higher a/r. Even on the 70-80% of the brakes Rhythm is simply flying - very slowly, calmly, with very low glide, while maintaining a sane handling. Even at large strokes the control does not become too sharp, the glider forgives even quite noticeable piloting errors, but it is surprisingly easy to control the glide angle. It's also easy to correct the errors in the course and roll - the effectiveness of the highly clamped brakes is enough for that. As a result, you can safely go to the target with a height excess of a couple of meters - at the end of the approach this excess height can easily be removed by strongly clamped brakes, and you just go down in a smooth, quiet manner. The high dampening of the Rhythm very much helps when landing on accuracy in the bumpy air which tends to bring down the Rhythm from the trajectory given by the pilot.

Comfort and feedback

It's not a glider, it's rather a kind of a tank! It is clear that a glider with such a modest a.r. simply can not be sharp and uncomfortable - but Rhythm also has long rods in the leading edge, which provide this product of the Korean manufacturer with remarkable resistance to collapses. It is interesting that Rhythm very willingly rustles and crunches with cloth, warning about changes in loads to different parts of the wing - but all these rustling and crunching in practice means almost nothing to the pilot, because getting a real, "combat" collapse on the Rhythm is almost impossible. At dangerously small angles of attack, the rods willingly take a load on themselves, and Rhythm with honor comes out of tense situations. Rustling and crunching are not so useful, from my point of view, to search and center the thermals. Rhythm's feedback is expressed primarily by changes in airspeed and a slightly less changes in loads on the hands. The harness gives very little useful information. As well as it is typical to a wing with low a.r., the Rhythm is absolutely not inclined "to wave with ears", behaves very "monolithic" even in strong enough turbulence. Roll and pitch damping is at a high level even for the EN A level, although there are some special features. Falling out of the thermal, the Rhythm is inclined to suddenly "shoot" forward with an external half-wing, and it is desirable to slightly hold it with an external brake. But you can not do this - it still will not collapse.

Dynamics and energy retention

Normal average level for the school-training-accuracy wing. Having well tried and clearly knowing what and how to do, the pilot can quite achieve from the Rhythm wingovers and energetic spirals - but if you do not ask the wing about it very clearly and persistently, it will try hard to protect the pilot from sudden changes in the trajectory and unpleasant movements on roll and pitch.

Asymmetric collapse

Perfect! It's not easy to provoke a collapse due to relatively high load on A riser. The collapse goes around 20-25% chordwise, and sturdy rods in the leading edge prevent the collapse from going further. In fact the typical collapse cannot fully develop, the half-wing remains partially inflated and reopens instantly after releasing the A riser. The trajectory deviation and surge are almost inexistant. The similar collapse and opening behaviour is typical for well-known Cayenne5 from Skywalk.

Prestall during thermalling

Perfect. In general the entry level wings rarely have a prestall regime, but Rhythm has it, maybe because it is half entry-level, half accuracy wing. The regime develops in a smooth and predictable manner, the pilot has a couple of seconds to recognise te situation and to correct it. The surge angle during recovery is around mere 20 degrees, and it's easy to conserve the thermal spiral during recovery and after.

Conclusion

The Rhythm is a very specific glider for a narrow range of application: entry-level school flights and accuracy. But when used as implied the Rhythm really excels. High dampening and calm reactions to turbulence and pilot input are good for beginners, and the brilliant ability to nicely controllable low-speed flight with very low glide is just what you need to win an accuracy competition. When you try to soar or to make some XC, the Rhythm shines much less. Even in EN A category, there are wings with better overall performance. But i'm happy to conclude that this Rhythm is so user-friendly that it can be used from the very first flight. The Rhythm strangely has lots in common with mini-wings: low a.r., specifict polar curve, amazingly compact and nice turn at high brakes travel... but with much less speed compared to mini-wings which makes the Rhythm much, much safer. Okay, it's hard to fly far with Rhythm, however You may land almost everywhere with minimal risk.

Pros

  • High passive safety
  • Calm and friendly behaviour
  • High resistance to collapses
  • Unexpectedly good ability to turn at low speed
  • Very low glide at low speed, perfectly controllable low speed flight

Cons

  • Modest overall performance

I would like to express my gratitude to Rinat Sabitov (Russian DaVinci dealer) and to DaVinci Gliders for offering the Rhythm for testing.

Text: A.Tarasov / testfly.ru, R.Sabitov

Foto: I. Tarasova, A.Tarasov

 

 

 

 

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Производитель Davinci
Сертификация EN A
Информация на сайте производителя dv-gliders.com
Информация на сайте дилера altair-aero.ru
Класс Entry level, accuracy
Год разработки 2017
Технические характеристики
size M
area ,m2 25,1
a.r. 4,7
a.r. projected 3,38
cells 36
closed cells 8
lines height, m 7,15
lines scheme A2A'1B4C3
weight, kg 5,3
total in-flight weight, kg 80-105
cloth Dokdo 30DFM 41 g/m²
lines Edelrid, Liros
Условия тестирования
flysites Tenerife
harnesses Sky Country SeCtor
total in-flight weight 100 kg
Результаты
build quality
8/10
longevity
9/10
ground handling
9/10
takeoff
9/10
Vtrim
8/10
Vmax
8/10
glide @Vtrim
8/10
glide @Vmax
7/10
Vymin
7/10
Vymin in turn
6/10
brakes efficiency
8/10
weight shift efficiency
7/10
control precision
7/10
control precision in turbulence
8/10
airspeed feedback
7/10
brakes feedback
7/10
harness feedback
6/10
comfort, dampening
10/10
collapse resistance @Vtrim
10/10
collapse resistance @Vmax
10/10
asymmetric collapse
10/10
low speed flight
10/10
prestall
9/10
Средняя оценка
8.17
1