XK X251 whirlwind (in construction) - RC Groups
Shop our Airplanes Products Drone Products Sales
Thread Tools
Mar 23, 2016, 03:45 AM
Registered User
SeByDocKy's Avatar
Mini-Review

XK X251 whirlwind (in construction)




EDIT: BE AWARE, XK INTRODUCED RECENTLY A NEW VARIANT OF THE FC: NO MORE ACRO BUT RATITUDE MODE INSTEAD. IT'S MORE EASIER FOR BEGINNER BUT LESS FOR ADVANCED FPV PILOTS. THEY ALSO REPLACED CARBON LEGS BY PLASTIC ONES.


EDIT 2 (07/24/16): BE AWARE, REAR SCEWS HOLDING THE LANDING GEAR BRACKETS ARE TOO LONG AND CAN DAMAGE TWO FETS OF THE ESC BOARD AS DEPICTED BELOW.







PLEASE REDUCE THEIR LENGTH FOR SAFETY





INTRODUCTION

Clearly since few months, we can see more and more cheap toy-quadcopter directly equiped of a brushless setup, of course thanks to some 4-in-1 cheaper ESC boards. After the very sporty JJRC X1, here is the XK X251 Whirlwind also sold around 125 USD. WIth the X251, a real "accro" flight mode is available and thanks to the presence of the Futaba radio protocol, we can expect great control range as well.


BOX CONTENT



+ 1 x XK X251 (with a 2S 950mAh LiPo w/ balancer plug)
+ 1 x Transmitter X7 (using 6xAA batteries not included)
+ 1 x Charger unit (2S balancer plug)
+ 4 x Spare props (2 CW, 2 CCW)
+ 1 x Allen key
+ 1 x Screw driver
+ 1 x Instruction manual (Chinese but please find the english PDF attached)

OVERVIEW


-Front view




-Side view



Each arm is well jailed into the main canopy stucture.



I am confident about crash durability. Sound to be real Carbon ... A good news



-Rear view

On the read side, you can find a bright LEDs turning to green in 6G mode and to red for the 3D/accro mode.



-Upper view



-Bottom view

With the battery inserted





You can find this ovoid hole where inside is located the bind button



As soon as you will need to match the X251 with another S-FHSS radio protocol, please press 1s this button. The status LEDS should turn off then lunch the binding procedure.

The battery connexion is done via the 2S balancer plug no more via classic lead connector such as JST.



Landing skid are made with plastic tubes





Landing skid system is solidly attached to the main structure



-Weight



Less than 215g with the battery installed, it's pretty light. A good news for the US market, no FAA registration required



Arms

As said previously, each arm are in plastic covered but there are in carbon.... They have 9mm of diameter and sound solid and well attached to the main central body.



Prop

Props are a little unconventional with a thinner hub (4mm)



Unfortunatly, it won't be very easy to install 5mm model. For XK it's an indirect way to sell more spare.



Prop cap are M4x0.7. For CW motors, you will need CCW/left hand model



Unfortunatly, as you will in my firt demo flight, I lost the front left one ...

Motors

Motors are 1307 type, so slightly taller than 1306 classic format.





The shaft section offers two diameters. The outter one is 5mm



while the inner is M4=4mm




For CW motors, a white dot is printed on the top of the shaft



Front lower motor pod are shinning in green colors while rear ones in red color. Ideal for night flights






LiPo

A 2S 950mAh LiPo with 25C as discharge rate... so pretty good. Unfortunatly, no main lead connectors installed. It means, you can really use
a professional charger and be forced to employ the provided one. With it, 2 hours are required to charge the LiPo (the red led should be turn off
when the battery is charged)









An alternative model can be installed, the turnigy nanotech 950mAH with JST connector





Last edited by SeByDocKy; Jul 24, 2016 at 02:58 AM.
Sign up now
to remove ads between posts
Mar 23, 2016, 03:46 AM
Registered User
SeByDocKy's Avatar
FPV module

Here is the pinout of the camera plug, so perfectly compatible with the V686G FPV module & the Yi-Zhan X6 one






- With the V686G







225g with the V686G module



- With the Yi-Zhan X6 FPV kit





235g with the YZ-Zhan X6 module



Disassembling

The camera port connector is a 4 positions 1.25mm mini-JST model.



No problem to split in two the canopy after the 5min unscrewing session (13 screws to remove)





The blue RF daughter board is installed on top. Here, we can find the CC2500 RF chip associated with the Futaba S-FHSS protocol.
In bottom right location, the invensense MPU6050C for the 6-axis stabilization. No USB slot for a direct software connexion but a free UART port is here.



The micro contact button is the bind button





Some of the FET populating the 4-in-1 ESC board






Transmitter

The X7 radio uses a deluxe and large chassis.



Versus the XK X350 radio, notice the presence of this red toggle button associated with the camera recording.
The right switches are the throttle hold (safety switch cutting immediatly motors) and the dual rate respectively. The left switches
are the 3D/6G and stabilized/accro ones respectively. If you turn on the accro mode, the main difference between the 3D/6G will be about maximum pitch&roll rates. In 3D of course, you can perform easy manual flips.

The top left switch is actually useless (but can be used) since no real 3D/inverted capacity

Gyro (6G/3D or call them Horizon/acro via the lower left switch Gear ) 75/25

Tcurve

point|top left switch (normal = FMOD0) point| (not used = FMOD1)
1 | 00 1 | 00
2 | 25 2 | 25
3 | 35 3 | 35
4 | 55 4 | 55
5 | 75 5 | 75


Pcurve

point|top left switch (normal = FMOD0) point| (not used = FMOD1)
1 | 60 1 | 60
2 | 60 2 | 60
3 | 60 3 | 60
4 | 75 4 | 75
5 | 100 5 | 100



For a more beasty machine in acco, you can play with the unused FMOD/3D button like

Tcurve

point|top left switch (normal = FMOD0) point| (not used = FMOD1)
1 | 00 1 | 00
2 | 25 2 | 25
3 | 35 3 | 45
4 | 55 4 | 65
5 | 75 5 | 95



FAILSAFE test

XK XK251 Failsafe test (0 min 28 sec)


FIRST USAGE

XK X251 first & very short demo flight (Courtesy Banggood) (2 min 57 sec)


As you can see, unfortunatly I lost after few second the front-left prop cap. I am doing my best to find a replacement asap (tricky since it's in M4 left hand format)

EDIT 03/29/16

Ok I received a compatible M4 prop cap from a 1104 motors.

XK X251 new demo flight (Courtesy Banggood) (4 min 59 sec)


As you can see, the vertical punches are already impressive thanks to its super light weight. The X251 is for sure more stable than JJRC X1 but rates probably less extreme too.

Ok in the next video, a real test in a large open space ...

XK X251 "Whirlwind" maiden demo flight (Courtesy Banggood) (13 min 51 sec)


What to say...... just I LOVE IT !!!!!!

and super crash resistant .... Ok Ok maybe I regret the absence of colored props and a strong front LEDs to keep orientation.

CONCLUSIONS

If you are looking for a first brushless & cheap machine robust, fast, agile, able to carry a small möbius or FPV kit and with a great radio range.... you can't be wrong with the XK X251... For me it's almost the perfect machine. The 6G mode is ideal for beginners very stable. Later the 3D/accro mode will let you to fly in real racer conditions especially equiped with the 5.8G FPV kit. The XK X251 is for me better than the JJRC in a lot of points: better and programmable radio, better lights, better radio range, real accro/3D mode available, more solid and lighter.. What else ? The XK X251 won my SebyAward Q1 2016.

UNBOXING

XK X251 "WhirlWind" Unboxing and quick analysis (Courtesy Banggood) (22 min 24 sec)


PROS

+ Super RTF packaging
+ Robust
+ Great punchout
+ Futaba S-FHSS protocol (range > 300m)
+ Accro mode (3D mode)
+ Compatible with V686G & Yi-Zhan X6 modules
+ Good X7 programmable radio
+ < 250g even with a FPV camera
+ Real JJRC X1 competitor
+ One of the cheapest potential FPV plateform
+ DeviationTX compatible (with a CC2550 RF chip installed)

CONS

- No power switch
- No arming/disarming sequence (potentially dangerous)
- No front LED (to help to keep orientation)
- M4 prop cap
- No lead connector for the LiPo
- No programmable settings X6/X7 have 10 memory banks

This quadcopter have been courtesy provided by Banggood in order to make a fair and not biased review. I would like to thank them for this attitude.
You can find it actually for 126/136USD at http://www.banggood.com/XK-X251-X251-A-With-Brushless-Motor-3D-6G-Mode-RC-Quadcopter-RTF-p-1038369.html
Last edited by SeByDocKy; Apr 30, 2016 at 02:57 PM.
Mar 23, 2016, 03:47 AM
Registered User
SeByDocKy's Avatar
reserved
Latest blog entry: Youbi XV-130 130MM FPV Racer
Mar 23, 2016, 03:05 PM
Fan of just about anything RC
SoloProFan's Avatar
I think the lack of disarming comes from the helicopters, where it's common to just switch on the throttle hold switch when powering on the heli. All this throttle up, than down, or other stick combos to arm the motors, that are common on (RTF) quads, are left out.

I agree it's something to be aware of, but coming from helicopters into the quad world, seeing other methods instead of throttle hold, was actually feeling weird, and needed getting used to.
Last edited by SoloProFan; Mar 23, 2016 at 03:10 PM.
Mar 23, 2016, 03:24 PM
Registered User
SeByDocKy's Avatar
Quote:
Originally Posted by SoloProFan
I think the lack of disarming comes from the helicopters, where it's common to just switch on the throttle hold switch when powering on the heli. All this throttle up, than down, or other stick combos to arm the motors, that are common on (RTF) quads, are left out.

I agree it's something to be aware of, but coming from helicopters into the quad world, seeing other methods instead of throttle hold, was actually feeling weird, and needed getting used to.
Yes, as you already knows, the X7 radio is used for both helicopters and quads...

Really I got very positive impression with this X251....

PS. Sorry, the web sever hosting my photos is down for at least the next 10-12h
Latest blog entry: Youbi XV-130 130MM FPV Racer
Mar 23, 2016, 03:29 PM
Fan of just about anything RC
SoloProFan's Avatar
Quote:
Originally Posted by SeByDocKy
Yes, as you already knows, the X7 radio is used for both helicopters and quads...

Really I got very positive impression with this X251....

PS. Sorry, the web sever hosting my photos is down for at least the next 10-12h

How about uploading the photos to a blog topic on your personal page on RCG? Would also make the pictures load a lot faster. Each of your topics that has a lot of photos, often takes 10 seconds or more to load
Mar 23, 2016, 03:33 PM
PALE OTAK KAU!!
KCreep's Avatar
This is everything the X1 should be. Programmable radio, acro flight mode, Futaba compatibility, compatible with several FPV cams and price is only jacked up by $10-20 vs the X1 price.

I can sense this will be more popular than the X1 if problems are few and far between..
Mar 23, 2016, 03:37 PM
Registered User
SeByDocKy's Avatar
Quote:
Originally Posted by SoloProFan
How about uploading the photos to a blog topic on your personal page on RCG? Would also make the pictures load a lot faster. Each of your topics that has a lot of photos, often takes 10 seconds or more to load
well ... I am already recuding photo's size to max 720p resolution. My experience with RCG personal page is a reduced audience IMHO..

Yes sorry for the time to load all my reviews but at least most of détails are here directly
Latest blog entry: Youbi XV-130 130MM FPV Racer
Mar 23, 2016, 03:39 PM
Registered User
SeByDocKy's Avatar
Quote:
Originally Posted by KCreep
This is everything the X1 should be. Programmable radio, acro flight mode, Futaba compatibility, compatible with several FPV cams and price is only jacked up by $10-20 vs the X1 price.

I can sense this will be more popular than the X1 if problems are few and far between..
I agree... and I think price will drop for the X251 relatively fast
Latest blog entry: Youbi XV-130 130MM FPV Racer
Mar 23, 2016, 11:28 PM
Registered User
I wonder how low in price the JJRC X1 will drop.
Mar 24, 2016, 02:47 AM
Registered User
the thing is,is it controllable?
Mar 24, 2016, 04:08 AM
Registered User
Quote:
Originally Posted by DroneRequired
I wonder how low in price the JJRC X1 will drop.
I think they are trying to run out all their stocks with the current promotional price of USD 85. Should there be any remaining ones after the XK X251/252 is launched then it shall be priced even lower. Even more so if the XK X251/252 could draw up an early bird sale price of USD 100 that will definitely shake them up.
Old Mar 24, 2016, 04:31 AM
lorenzo28469
A moderator felt this post violated the following rule: Excessive Advertising (Spam). It is temporarily hidden while lorenzo28469 edits it.
Mar 24, 2016, 05:30 AM
Fan of just about anything RC
SoloProFan's Avatar
Quote:
Originally Posted by SeByDocKy

A 2S 950mAh LiPo with 25C as discharge rate... so pretty good. Unfortunatly, no main lead connectors installed. It means, you can really use
a professional charger and be forced to employ the provided one. With it, 2 hours are required to charge the LiPo (the red led should be turn off
when the battery is charged)

You can split the balance connector in a balance and charge lead. All you need is a 2S extension wire, cut the red and black wires, and connect a wire with a plug that is compatible with your charger, red to red, black to black. When a LiPo has seperate discharge leads and balance leads, underneath the shrink wrap the same connections are made. Red to pos, black to minus, and middle balance wire between where pos of one cell connects to neg of the other cell of the 2S pack.
Mar 24, 2016, 05:40 AM
Registered User
SeByDocKy's Avatar
Quote:
Originally Posted by SoloProFan
You can split the balance connector in a balance and charge lead. All you need is a 2S extension wire, cut the red and black wires, and connect a wire with a plug that is compatible with your charger, red to red, black to black. When a LiPo has seperate discharge leads and balance leads, underneath the shrink wrap the same connections are made. Red to pos, black to minus, and middle balance wire between where pos of one cell connects to neg of the other cell of the 2S pack.
Yes for sure by modding the LiPo... What I mean here, I regret the non-presence of the main lead connectors.... Ultra beginners won't do the battery mod and will buy official spare....
Latest blog entry: Youbi XV-130 130MM FPV Racer