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Old May 16, 2015, 07:30 AM
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Mini-Review
Cheerson CX-90A Brushless Helicopter



Introduction

I'm back. I guess we don't have time for a long-winded review so I shall cut to the chase and get on with the important bits. Feel free to ask questions if I had missed anything; I'll try my best to answer them or seek advice from Banggood.

Pros:

+ Fast and powerful - The 2S power plant and large collective pitch range allow CX-90A to be an aggressive 3D helicopter. Like the HCP100S, due to my limited skills, I am unable to unleash its full potential. Loops are easy and fun, but I had problems flipping to inverted as shown in my review video. Maybe it was because I used the V977 TX, which may not have enough negative pitch.

+ Tail holds very well - Tail locks in nicely during pitch pumps. No visible wags during fast forward flight or transitions between fast-slow flights. It has piro compensation but it's not perfect. Don't count on it.

+ Works with V977 and DeviationTX transmitters - The stock TX is crap so I flew it with my V977 TX. The collective pitch range is lower with the V977 TX so that's another benefit. As it works nicely with V977 TX, DeviationTX users will be able to fly CX-90A with their "deviated" transmitters.



Cons:

- Not very stable - the stabilizing effect is relatively low and the pilot has to apply quite a bit of corrections during hover. I suspect the low level of stabilization is to allow it to be more agile and aggressive during 3D flight.

- Issues with tail rotor design - Tail assembly seems heavy and that shifts the center of gravity backwards. Tail-heaviness can be felt during hovering as well as during the start of forward flight. Tail blade is very fragile. I installed my tail rotor too tightly and the thing snapped right after take off. The heli plummeted like a rock for 1 feet, whew! The (pinion?) gear slides during a crash. This may help prevent it from stripping but the downside is that it may pop out and be lost in the grass. Sometimes the tail motor slides towards the nose, causing the gears to not mesh together. Simply push the motor towards the tail.

- Poor transmitter - Maybe mine was a pre-production sample. The sticks feel loose and flimsy. My commands translated to the swashplate feels like they suffer from low resolution. This may be the "disconnected" feeling that some pilots refer to. The numerous buttons beside the LCD do nothing. There is no way to change rates or pitch range (which is possible on certain versions of V977 TX).


Notes:

1. Not for beginners - CX-90A is like a larger version of V977 but without 6G mode. It is very agile and due to its weight, it can be dangerous to the pilot and the surroundings. Be careful!

2. Fly in large, open spaces - It is fast and it gets near or away from you very, very quickly.

3. Recommended spares - tail rotor blades, tail gears, canopy. The rotor blades and tail boom are surprisingly durable.


Links

CX-90A RTF: http://www.banggood.com/Cheerson-CX-...-p-970959.html

CX-90A BNF: (hope it's available)
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Old May 16, 2015, 07:30 AM
FyreSG is online now
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新加坡的飞儿
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Resources

Videos

Unboxing
Preview: Cheerson CX-90A Brushless CP 3D Helicopter (1 min 7 sec)


Review & Test Flight (with V977 TX)
Cheerson CX-90A Brushless CP 3D Helicopter - Review & Test Flight (9 min 0 sec)


Binding demonstration with V977 TX
Cheerson CX-90A Brushless CP 3D Helicopter - Transmitter Compatibility / RF Protocol (1 min 8 sec)
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Old May 16, 2015, 08:49 AM
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Thanks for the review.

You mention under "Poor transmitter", "There is no way to change rates or pitch range (which is possible on certain versions of V977 TX)."

Are you saying that using a V977 TX you will have access to the same rates (low & high) as with the V977?

And, you say it does not have 6G, but BG's Description states "Gyro:Six axis". Are these not the same (sorry, still learning)? And on that note, did you try the V977 TX's 3D/6G button? Does it do anything? Is it needed, like with the V977, to access Idle-up mode?
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Old May 16, 2015, 09:15 AM
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Thanks for asking. I realize the ambiguity now.

There are high and low rates when using V977 TX. I can tell the difference between the high and low rates: swashplate tilts more (on the bench) and the cyclic feels more responsive (while in flight).

With the stock transmitter, I don't feel like it is in 6G mode. There is no way to switch between 3D or 6G mode with the stock TX. That said, I did not try 6G mode with V977 TX. I hardly switch to 6G mode with my V977 or V931 so I totally forgot about this function. I shall try this next.

I wish my V977 TX allows me to adjust the collective pitch range like some special versions of the V977 TX. The stock TX is very bursty as it has a large collective pitch range, but it is poorly made. Maybe it was damaged before it reached me; maybe the sample was poorly made. I hope the final version will be ok. Otherwise, we'd have to rely on V977 TX to fully appreciate this helicopter.
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Old May 16, 2015, 10:00 AM
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Looking forward to what you find, thanks.

Hopefully they will provide a better TX (and implement all that should/could be on it) when they become available.

As far as adjusting pitch range via TX/RX, I remember reading that BG/WLtoys were saying that all should be able to, but that in fact only some RX boards were able to be adjusted. I actually ordered a spare RX, in part because I hoped to get one that could, but, I've not gotten around to testing it yet.

If this is true, and the capability is related to the particular V977 RX, might it be possible the CX-90A has this capability too? If I'm not too far out in left field (or lost in the trees), you may want to try it with the V977 TX (and maybe even the stock TX).
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Old May 17, 2015, 03:38 AM
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Interesting review FryeSG ,looks like some good and some bad in the one you got ,always a little early to judge if you have a preproiduction model ,certainly the tx looks half finished with the right stick not even centering and buttons not working ? It would be a shame if this is the way its intended to be ,it would put me off a heli that otherwise i might be interested in.
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Old May 17, 2015, 06:17 AM
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Yo

So I guess you change the pitch range

by moving the metal pushrod link in or out on the servo arms ,

to get the range you want

Im a bit worried on geared tails , can you just have a say v911 main motor on the tail with a smaller prop ?
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Old May 18, 2015, 02:37 AM
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Yo

Maybe an old V922 main motor would do OK out on the stern, no gears ?
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Old May 23, 2015, 03:08 AM
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Hi FyreSG

Great review, as always.

I wonder, could I possibly ask, if youve been able to try CX 90 in 6 axis mode ?.
This heli is first on my list to buy when available, and when you demomstrated it shares the v977 protocol, happy days. I do like flying v977 in both 3 and 6 G.
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Old May 23, 2015, 08:27 AM
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Hi FyreSG,

Is it the same size as walkera master cp?

Where can I see the real helicopter itself in Singapore?

Thanks.
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Old May 23, 2015, 08:40 AM
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Sorry guys for the lack of updates! I don't really have time to work on CX-90A right now.
Quote:
Originally Posted by NX-687 View Post
Maybe an old V922 main motor would do OK out on the stern, no gears ?
I think it will make the heli tail-heavy and that will not be good. I suspect the gears are there to either increase or decrease the output of the motor so that the blades spin at an optimum powerband.
Quote:
Originally Posted by Spoon68 View Post
Hi FyreSG

Great review, as always.

I wonder, could I possibly ask, if youve been able to try CX 90 in 6 axis mode ?.
This heli is first on my list to buy when available, and when you demomstrated it shares the v977 protocol, happy days. I do like flying v977 in both 3 and 6 G.
Thanks! I will examine 6G mode with V977 TX in detail but from my quick check, it is affected by V977 6G Hover Calibration setting. I applied a lot of left trim while I calibrated my V977, and this is saved in the TX. When I flew my CX-90A under 6G, it kept flying left and I couldn't correct it. I need to find a way to reset the Hover Calibration setting before reattempting to fly it with V977 TX at 6G mode.
Quote:
Originally Posted by rchobbyfly View Post
Hi FyreSG,

Is it the same size as walkera master cp?

Where can I see the real helicopter itself in Singapore?

Thanks.
Sorry, I haven't seen a Master CP in real life so I can't comment. You may need to compare with the dimensions stated in the product website.

I don't think you can find it on sale here in SG. In fact, it is currently only available for pre-order in China. If you're keen, we could meet up for a test flight.
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Old May 23, 2015, 11:55 AM
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Quote:
Originally Posted by rchobbyfly View Post
Hi FyreSG,

Is it the same size as walkera master cp?

Thanks.
Definatly smaller than Master CP . I have Master CP , Ive placed V977 beside
If you compare it to FryeSGs picture also with V977 , you can see the difference. Its some where in between
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Old May 23, 2015, 01:22 PM
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Frye so the cx-90 should fly with my deviation devo 8s using the v977model, if so i might buy a bnf
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