DaVinci XChord, or I Sell My Zeno

Hi-tech 2-liner with PWC ambition but user-friendly mood!

Construction. No! It's not a Zeno copy (as the rumours say sometimes). Definitively the XChord has been designed with Zeno in mind, but this is a new, original design having its own advantages and drawbacks but targeting the main aim to overcome Zeno in many aspects.

Let's begin from risers which have a very specific "Zeno, improved" look and feel. Big brake handles (Zeno has smaller ones) with swivels (which Zeno has not), wisely placed brake line extender (with Zeno, it always comes between your hands and rear handles when you try to catch them), small and very convenient rings for brake lines (Zeno has unreasonably heavy metal pulleys)... There's also a lot of similarities with Zeno (the schemes and geometry of risers are almost identical) but all that small improvements give you a very different feeling which i really like.

The canopy shares the same approach. The first thing you see is the very familiar, Zeno-like planform with straight leading edge and specific ears. The internal construction is also more or less Zeno-like, at least at first sight. But if you dive a bit deeper than many differences appear. XChord has more cells (82 instead of 78 for Zeno), different wing areas and weight ranges, different lineset and -- wow! -- monstrous plastic rods running almost 100% chordwise. The cloth is also different, promising better solidity and longevity compared to Zeno (for the cost of being very slightly heavier).

Takeoff and ground handling. It's something special, mostly due to that incredible plastic rods. In moderate and strong wind conditions the glider needs almost no pull on A risers, stepping back and firmly applying weight is enough to bring the glider overhead. The trailing edge needs some special attention because the wind can turn it downside up hampering the further operations with the glider (the Mantra R10.2 had more or less similar behaviour). During its rise the XChord demands special control on roll, it easily sweeps on one side if the initial pull was not perfectly symmetrical, and it's not so easy to counter the roll if it appears. Applying lots of weight on one side generally helps, the brakes being not very efficient before the glider comes up. The inflation takes some time, especially for the rear part of glider which tremors amply during inflation (this effect also occurs with Enzo 3). Due to the relatively long inflation process the glider reveals no powerful surge on pitch, coming up smoothly and steadily.

With light wind and no wind the things are still largely within admittable for a top EN D. You need to apply a long and powerful pull on A risers until the wing comes fully overhead. The rods prevent the wing from losing its shape even if it is partially deflated or producing no lift, so the errors during no wind takeoff may produce strange canopy configurations which are not always easy to untangle (same for the top level parafoil kites with AR>7 and lots of plastic in the leading edge).

The overall performance levelseems to be at least on par with Zeno, maybe even better. But the performance (however at the very very top of its class!) is definitely not the strongest point of XChord. This glider tries to redefine the performance-to-accessibility rate for top EN D, and i see very few possible concurrence for XChord on this specific criterion. It's truely amazing to have the performance level rivalling Zeno, but with more accessibilty and less headache.

The first difference: pitch dynamics and energy retention. The XChord is rather active on pitch, rocking back and forward even in relatively calm air, but all these pitches are limited both in amplitude and speed. The Zeno moves much faster on pitch; XChord is more dampened but grabs more energy on each pitch, impressively converting speed to height and vice versa. Imagine that you have the main lines 1-2 meters longer than they are in fact, the feeling would be very similar. This "calm power" demands a specific way of glider control: short but well-dozed inputs in precise moments of time instead of almost-constant "thrill" needed for gliders with less pitch dampening. In fact the XChord demands less attention than Zeno but the relatively slow conversions of speed to height and back are not very favourable for proximity flying near a slope. You just need some time to grasp the rhythm of pitch and to make the brake inputs a bit in advance (compared to Zeno).

The second difference: glider feedback. The feedback which XChord gives to his pilot is more "classic", more explicit, much easier to read and understand than the Ozone-style feedback. The glider reactions to turbulence are more calm, less nervous but more pronounced compared to Zeno. The airspeed changes have an impressive amplitude, the glider tends to gain lots of speed coming out from thermal cores. The speed loss while entering the cores is also very well marked, but fortunately there's no that strange effect well familiar to Zeno owners when the glider keeps the higher angle of attack and low speed for some time with no obvious reason. The XChord recovers from occasionally occuring high AOA in a relatively fast and well predictable manner.

The changes in load on main carabinners and the speed and brakes feedback while thermalling are very impressive: this glider has lots of power which needs a careful control! It's interesting that, despite of that "high power" feeling, the "snaking" and "wobbling" spanwise effects are at their normal level for a top EN D wing, the XChord is not more "wobbly" or "snaky" than Zeno.

The brakes feedback is very bright and well present, easy to decode, the typical brake charge being on par with Zeno.

It's difficult to say is XChord generally prone to be thrown off the thermal cores or to be sucked inside. In strong and narrow cores it's more possible that XChord will be thrown off; in weak but wide lifts the XChord seems to find the right way himself, demanding almost no assistance from the pilot. The overall behaviour while thermalling is somewhat between Zeno and the famous Icepeak 6 which, i think, still remains the easiest top-level 2-liner. XChord is more demanding that Icepeak 6 but definitely easier and more "user-friendly" that Zeno. Personnaly i needed around 20-30 minutes of thermalling with XChord to build some initial confidence and to feel myself more or less comfortable; with Zeno, i've got the similar feeling after 10 or maybe even 20 hours of airtime!

The third difference: the turn. For Zeno, the turn behaviour (especially in thermals) is one of the weakest points. Keeping the Zeno in narrow cores is always a heavy job demanding lots of brake input and very ample weight shift. With XChord it's much easier. The brakes efficiency is higher (compared to Zeno), but the glider especially "likes" the weight shift which is also very, very efficient. In fact, the marked brake input is rarely needed, and in general you may easily keep the XChord in a nice thermal spiral with reasonable bank angle using the moderate weight shift and small amount of brake input.

Could not find if XChord "likes" the flat or the steep spiral: it's easy to make both of them! It's most typical to keep some 30 or 40 degrees of bank while thermalling with XChord, the flat turn is rarely needed.

The wingovers are very nice, mainly due to high brake efficiency. It's better being precise on weight shift during the wingover because the glider easily gains lots of airspeed, and the inaccurate control may lead to unpleasant effects like being thrown off and having some crazy pitches (which however do not generally end with collapse). The Icepeak 7 Pro does it faster but also demands more careful control.

The steep spirals come in easily. Didn't force the glider to go down at really high speed, the sink rates around 10 m/s are okay.

Polar and high speed flying. This is the main destination of race machines like Zeno and XChord, and the measures say that both gliders have identical indicated airspeed: 34-36 km/h trim speed, 46-48 km/h at first bar, 57-58 km/h full speed. At the time of writing this report i had no chance to fly XChord side by side with other top EN D and/or CCC wings, but being a Zeno pilot during one seasion i can say that XChord always overcomes my glide estimations. Did some XC flights demanding precise evaluation of glide (flying above no-landing places), and XChord was always coming to planned destinations a bit higher than i was expecting. The counterwind flying performance also impressed me a lot: okay, i'm still subjective, but it appears that Zeno has less counterwind performance (less glide at high speeds).

Floatability. XChord appears to be a great floater, rivalling the Zeno again. Flying at my favourite spot in weak conditions revealed the possibility of taking thermals and ridge lift really low. XChord easily gains height even in small lifts, partially due to nice floatability, partially because of efficient and relatively simple thermal turn. Had no Zeno near me to compare but think that XChord could have some advantage while thermalling. Flying XC the day with scrappy thermals near the Enzo 3 brought me further -- the Enzo 3 pilot (a very expericnced one!) gave up after his first low save and went back to the takeoff, leaving me alone in the air.

XChord's landing behaviour and low speed flying has some peculiarities. The brake travel is reasonably long, efficiently killing the glide at speeds near the stall limit, but the brake loads have almost no increase near the stall point. Playing with the glider close the the stall limit reveals that it's not so easy to feel the glider entering the stall; the visual control becomes very important during these games. The drop of the glide near the stall point is very pleasant for top landings in windy conditions, but the risk of occasionally getting into stall is relatively high (Zeno prevents better about the stall vicinity), so to be practiced with extra care.

Conclusion. During a whole year the famous Zeno had no alternative encouraging Ozone to tweak the prices above any reasonable limit and forcing pilots to tolerate the subtle temper of this race beast with Mantra R-series pedigree. Now it's over! Meet the XChord: a naturally born Zeno-killer. However the XChord may appear a copy of Zeno (and being for sure created keeping Zeno in mind), it's definitely a new design aiming to overcome Zeno. And it really does! Better turn. Explicit and well-readable feedback. More user-friendliness and comfort. All this combined with the level of performance at least on par with Zeno or even better. A brilliant debut which deserves glory and recognition. Bravo DaVinci! And, just to confirm that i'm not too subjective -- i'm selling my Zeno now. No joke!

Strong points

  • The overall performance level at the very top of the class
  • Good handling
  • Good balance of feedback and comfort

Weak points

  • The brake loading has almost no change near the stall point

What is specific

  • The takeoff behaviour (due to long plastic rods)

Special thanks

  • DaVinci Gliders (glider, logistics)
  • Rinat Sabitov (logistics)
  • Dmitry Gavrikov (foto)

Foto: A.Tarasov, D.Gavrikov, DaVinci