Davinci X-Chord review

Hello to all eagles out there! 🙂

I’d like to share with you the XCHORD test report by Alexei at “Test Fly ” – http://testfly.ru/

Had a rest day with the conditions being too weak for good flying. So here are my first impressions on XChord:

The take-off

Take-off and ground handling is very specific, mostly due to monstrous plastic rods running almost 100% chord wise. 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. 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. 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 sudden surges on pitch, coming up smoothly and steadily. The overall performance level seems 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.

The flying

This glider tries to redefine the performance-to-accessibility rate for top EN D, and I see very few possible competition for XChord on this specific criterion. It’s truly amazing to have the performance level of Zeno with more accessibility 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, and much easier to read and understand than the Ozone-style feedback. The glider reactions to turbulence are calmer, 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 occurring high AOA in a fast and well predictable manner. The changes in load on main carabiners 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” span wise 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.

The thermalling

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 easier and more “user-friendly” that Zeno. Personally 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 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!

The fun

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 even a small error may lead to unpleasant effects like being thrown somewhere and losing the control over the situation. 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.

The landing

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 to the stall limit reveals that it’s not 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 is easier near the stall), so to be practiced with extra care.

The 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 simple thermal turn. Had no Zeno near me to compare but think that XChord could have a small advantage. Did a short XC today (around 30 km). The weather was among the strongest possible here: strong wind gusts, thermals up to +5 m/s (10 sec average). It was interesting to try XChord in relatively strong conditions. For sure it’s easier than Zeno. The gliders needs less control and gives more comfort.

The recovery

Had one ear collapse (a couple of sections, nothing to care about) and countered a bigger collapse (~50%) at trim speed. It was much more interesting: the leading edge broke at ~10% chord wise but it occurred with both brakes already pulled, so the collapse did not fully develop, and the glider recovered instantly. Didn’t see any tendency to cravat (which is a common problem for Zenos coming out of factory trim).

Final thoughts

Riding a strong thermal was funny 😉 much easier than with Zeno. The glider wasn’t thrown away, and it was easy to keep it near the core. Of course there was a lot of wobbling and some snaking but I had plenty of control efficiency to keep the glider where I need and to conserve the bank angle I want. Maybe still not the level of Icepeak 6 or Icepeak 7 Pro (which has fantastic thermal turn) but much, much better than Zeno. Did another flight in the afternoon with the primary aim to measure speeds. I have a Flymaster TAS probe which is a very precise and fair instrument. My Flymaster NAV indicates the IAS (instrumental airspeed) which does not depend on height and pressure. The results are strictly on par with Zeno: 34-36 km/h trim speed, 46-48 km/h at first bar, 57-58 km/h full speed. Don’t be perplexed by these relatively low speeds: IAS is the speed you could obtain flying at 0 m above the sea level at +15 degrees Celsius. The true airspeed (TAS) which depends on height and temperature was 5-7 km/h higher. Doing my measures I suddenly realised that something strange is happening with my glide. It was better than I expected! Could fly 4 km against 17-20 km/h wind and get back to the take-off with lots of height remaining. Still had no comp wing near me to compare but think that XChord may have better glide at high speeds than Zeno. The first bar is highly usable even in moderate turbulence, the glider appears to behave even a bit more comfortable than at trim speed. Didn’t fly a lot on second bar, need more airtime to explore the question.

Note from the manufacturer:

One of our test glider is at the Free Aero Magazine test team. They are having a test with M size our demo XChord. We should see the report in the near future.