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Old 06-27-2019, 02:10 AM   #1 (permalink)
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Default COMPARISON REVIEW: Nano S2 & Nano CP X

I have many months of experience with both the Nano CP S (2nd gen) and the Nano S2 (3rd gen). But I've never flown the 1st gen CP X. Multiple people here on HeliFreak have said that that the original Nano flies quite differently than either of the later two models, even in 3D mode. Must admit, I’ve always been curious.

Well, a few days ago I acquired a CP X from a fellow HeliFreak (thanks Chris!) and have put enough packs through it to give an initial review/comparison. I am writing this as someone who is most familiar with the S2 and will use its behavior as a basis to describe the CP X.

Both helis had the HH brushless mod installed.

Three-sentence summary

The Nano S2 is more stable, but the CP X is more fun. The S2 is a great trainer for learning maneuvers that with rudder movements that rely on piro compensation, while the CP X is better geared for high-cyclic 3D maneuvers. Both are great and serve different purposes.

Piro compensation: The good

Pirouettes are easier on the newer Nano S2. Plain and simple. This is where the newer model's introduction of piro compensation really shines. The S2 will better serve the pilot who is just learning upright/inverted orientations and stationary piros. The ability to crank the rudder stick and not worry about cyclic input as much—I say as much because the compensation is not perfect—cannot be understated.

With the CP X, constant macro cyclic corrections are needed during stationary piros. (While I'm no pro pilot, I found it nearly impossible to do fast-moving piros on the CP X. In fairness, it was quite difficult on the S2.) An experienced pilot will not have much trouble dealing with the lack of piro compensation, but it will create a larger hill for the newer pilot to climb.

Piro compensation: The bad

I have always felt that the Nano S2 was fighting my cyclic input while it was pirouetting. For example, imagine the S2 is pirouetting and you give a short burst of down-cyclic when the heli is tail-in. It ought to begin to move toward toward you and maintain that travel direction; at least bigger helis with proper FBL units would do so. But the S2 doesn't do that. Instead, the S2 rotor disc will quickly level-out and the heli will go into a stationary piro again. To get the S2 to continue traveling toward me, I would need to give a few more bursts of well-timed cyclic (or better yet, a slight stir of the cyclic).

Another way to say this is that the S2 sometimes feels like it's in some sort of Blade-SAFE stability mode even though it's nominally in 3D mode.

Now, I'm not saying the CP X will behave exactly like a proper larger heli if you go from a stationary piro to a moviing piro—it won't because of its lack of any sort of piro compensation. But at least it's not artificially stable.

Cyclic agility: So different!

Cyclic maneuvers like flips or agressive rainbows are quicker and easier on the CP X. This was my favorite part of flying the older model and why I found it more fun. The CP X feels similar to my T-Rex 150X or even my Oxy 2 with regard to how precisely & quickly I'm able to flip it.

In comparison, the S2 feels sluggish, especially elevator moves. In fact, after flying a few packs through the CP X, I did two things: (1) I gave more negative expo on my S2—right now I'm at –35%, which for Spektrum means more sensitive around center—and (2) I gave a fair bit of positive expo on my CP X—I think I'm around +15% now. Even with these drastically different exponential values, the CP X is quicker to flip and more enjoyable to go crazy in the air. I might need to go to –50% on the S2 for the two helis to even begin to feel the same.

(By the way, I even set up the two helis to have approximately the same max cyclic pitch. They really do fly differently! I will likely need to increase the S2's aileron and elevator travel endpoints on my TX.)

More than once I've seen HeliFreak posters say that the CP X was better than the CP S or S2. If I'm being honest, I thought they were just being cranky and basically saying "I never even touched anything with an accelerometer [like CP S & S2] and neither should you!" But I now better understand what they were saying. If I could rephrase this sentiment in terms of someone like me who is still relatively new to helis: The CP X will allow you to do more high-cyclic 3D maneuvers, whereas the S2 is slower, more stable, and more sluggish. This is again one of those cases where I think the S2 is better to learn on, but as soon as you look up the Game Genie code to unlock a certain maneuver, you're gonna want the CP X's agility. At least I do.

Can't do throttle curves on the S2. WHAT?!

There's a "feature" of the S2's FBL firmware that locks the throttle at 100% no matter what throttle curve you set up in your transmitter. Want a slower head speed with the S2? Sorry. Want to set up a V-curve in your transmitter so that you maintain constant head speed? Sorry.

You might say that on a tiny micro like the Nano S2 or CP X, 100% is fine, no big ideal.... That is true for me now, but wasn't true for me when I was initially learning to fly collective pitch helis. Back then I actually wanted a non-reactive head speed. 60%? Yes please! But even if someone is not an absolute beginner, the lack of ability on the S2 to customize throttle curves means that you can't maintain constant head speed as the battery voltage decreases during a given flight. On both my CP X and my T-Rex 150X (which don't have governors), I have different sets V-curves, one for the beginning of the pack when the voltage is high and another one for when the battery is about half spent and I need to simulate a governor by manually bumping up the power output (e.g., 80-68-65-68-80 and 100-88-85-88-100). With the S2 I don't have this flexibility. But I do with the CP X.

Horizon Hobby, why did you do this with the S2? Or was it unintended, as I suspect it was? (Given the existence of the firmware bug with throttle hold/cut on the Nano S2, my money is on it being unintended.)

Final word: Which do I like better?

There are features of both the S2 and the CP X that I like and don't like. I can best summarize it by describing what my ideal "Nano S3" heli would be: it would have the piro compensation of the S2 but the agility and customizability of the CP X.

I will be flying both helis. If I want to practice my aileron or elevator flips or aggressive rainbows, I'm gonna break out the CP X. If I want to practice small-radius nose-in or tail-in circuits (or anything else that requires constant rudder), I'd do the S2.

Both are great in their own way and serve different purposes.

Bonus video: First flight with the CP X

I filmed my very first flight with the CP X. Obviously the thoughts I communicate during the video were not as well-formed as they are now, so what you're seeing are just my initial impressions.

First flight with Nano CP X — Comparison to Nano S2 (11 min 3 sec)
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Brian — XLP 520, YGE 135LVT, IKON2 — Oxy 4 Max, YGE 65LVT, Brain2 — Oxy 2, YGE 35LVT, µSpirit — XK K110 — Horus X10S & OpenTX —

Last edited by xoexoe; 06-27-2019 at 03:21 AM..
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