Thread Tools
Jun 03, 2014, 10:07 AM
Registered User
SeByDocKy's Avatar
Thread OP
Mini-Review

JXD 389 "The Flying car"





INTRODUCTION


Since the success of the JXD 385, the Hubsan X4 clone using the V2x2 protocol, JXD is very active in the micro/mini quadcopter world.
Few months later, JXD announced the 388 and the 392 models still in microquad size and V2x2 compatible.
With this model 389, JXD is introducing an orignal combo concept: an hybridation between a quadcopter and a car... "The flying car" is born.




BOX CONTENT





+ 1 x JXD 389 (with a 14g 500mAh LiPo, rated 25C using a micro-Losi connector)
+ 1 x Controler (using 4xAA batteries not included)
+ 1 x USB charger (ending with male micro-losi)
+ 4 x Spare props (2 CW, 2 CCW)
+ 1 x Instruction manual (english/chinese)
+ 1 x Screw driver



OVERVIEW

This micro quadcopter-car is based on a H-frame of 140mmx130mm approximatively.




From left to right: JXD 389, SYMA X4, JXD 388 and the WLTOYS V272:



The upper body part have a nice sportive car canopy copying a bit lamborghini design. A total of 5+8 screws are closing the top part.
The upper canopy is scaling 11.2g.

The bottom part is welcoming the battery bay, a micro switch and fine steering tuning button


Each Arms are composed of two branches ending with a plastic pod jailing a coreless 8.5mmx20mm motors







8.5mmx20mm motors:



Unfortunatly, the pinion with 8 theeth is in pastic.


The 389 is based on a geared setup in order to improve vertical trust.



For me this part is the weakest point of this machine. When I opened the 389 box, I immediatly noticed that one of the prop was not spinning normaly. I found some friction/resistance during the prop rotation. I STRONGLY ADVICE TO CAREFULLY CHECK ALL GEAR/PINION JUNCTION BEFORE FIRST USAGE. If one prop is not correctly freely spinning (you meet some resistance during rotation), your MOSFET as well as your motors will getting warm and will be damaged. When I completly disassembled the motor pod, the shaft was perfectly spinning as well as the motor standalone. It's clearly indicate that junction between motor pinion and gear can be problematic with brand new plastic and/or after a crash. After some short flights (in order to not hurt the corresponding motor and MOSFET), the props started to spin normally. So if happens for you, please don't try more than 30s-1mm of flight.

The motorpod standalone:

You can notice than there is no ball-bearing installed. This last point can explain partially the eventual presence of friction in the geared setup. It's a real drawback.

Props are identical to the JXD 393 model, i.e. 88mm long

The battery bay is quiet small (25mmx45mm)

and welcome a 500mAh LiPo rated 25C using a micro-LOSI connector



As LiPo replacement, you can install a nanotech 750mAh 35C but with model,

YOU NEED TO INVERT POLARITY WITH THIS MODEL OF LIPO BE AWARE!!!!. .
With this LiPo I was able to fly more than 7mm.

When you remove the top canopy, you can access to the RX board as well as the car motor and steering servo

The car's motor part is located in the rear part.


The steering servo in the front

Two ultra thin wires are powering the servo and connectect to the M5 pins on the RX board

Front Leds are probably enough strong to allow Night flying




You can also access to the micro-switch to turn on/off the 389


On the upper layer of the RX board, you will find the "classic" Invensense 6050C the 3+3 axis stabilisation unit as well as the RF chip BK2423 (nRF24L01 compatible)



The 2.4G antenna is correctly tuned to 31mm



Finally, the total weight of the JXD 389 is 79g



The transmitter is copying the WLtoys TX desing. For the 389, the TX is including a LCD display, two shoulder buttons and 1 front button (the other ones are fake).
4 x AA batteries are required for the TX (not included)

The panel button allows to select between car and quadcopter mode. For other JXD models such as the 390, 391, 393, this button allows you to turn on/off lights.
The left shoulder button is selectioning between three speed mode. The biginner mode is the default one. If you press one, you will enter in the intermediate mode and if you press twice, you are entering in the sportive mode.

The right shoulder button is activating flips.
If you press this button more than 2s and put both sticks in lower-left position, you are entering in the gyroscope calibration procedure.

Gimbals are ok and will let allow you to control your quadcarcopter with a relative good precizion.




The TX daughter board is branded by "ABE". The same compagny you can find for the last SYMA model for example

By the way, this quadcopter is DeviationTX compatible with the 'YD717->Sky Wlkr' protocol (Actually flipping button and car/quad mode button are not yet recognized, probably soon)

The TX antenna is 31mm

I drilled a small hole in the canopy to install vertically the antenna in order to optimize control in the horizontal plan.



FIRST USAGE

To arm your quadcopter, you need to push/pull the throttle stick. After this operation, the LEDS becomes solid.
By default, you are starting in car mode. At beginner speed, the car is rather slow (3 km/h approximatively). The steering control as expected for such toy is not proportional but you can control your car relatively easily.
In the sportive mode, the car should run at 10km/h. Be aware that tire can pop out from the wheel time to time.

When you are entering in the quad mode, you immediatly notice that this small quad is relatively noisy probably due the absence of ball-bearing (direct contact of the metal shaft with plastic).

The quad is hovering around 40-45% of throttle. If beginner mode is rather slow, the yaw rate is not bad at all . It's a good news.
With intermediate and sportive mode activated, the pitch/roll angles are largely improved and the 389 can take very easily some velocity.
I noticed, especially outdoors that, when you are releasing the right stick, the quad is not immediatly horizontaly stabilized (as for many quadcopters). More, if you have a lot of speed, your quad can drift a long distance before immobilization. To air-break, you will need to action in the opposite direction. Flips are good and fast. You don't loose really altitude....

EDIT 06/04/14 I am wondering if this quad is really a 6 axis because no steadu hover when releasing right stick ....

At the end of the flight session, motors was warm, almost hot (> 40 degrees Celsius but < 60 degrees)

Unfortunatly, when you are in car mode, you don't have access to the the quad's throttle .... It would be nice, if at least the left stick controls would be available.

The range control is good. I was able to reach 50-60m without any problem and I can control it likely over longer distances . Controled by a Devo 7E, this quad becomes great to fly with ....


CONCLUSIONS

If one could expect that this hybridation between a car and a quadcopter would give birth to a mediocre toy, finally it's not the case.
Of course, the car part is less interesting compared to the quad part and what's a pity that in car mode, you can't access the left stick's controls.
But the quadcopter mode is fun: a stable and fast quad, it's good surprize.

I think in a near future, I will remove the car parts (motors, servo and wheels) and replace them with nanoFPV setup.




UNBOXING AND QUICK TESING

JXD 389 Unboxing and quick testing (Courtesy Banggood) (16 min 18 sec)

PROS

+ Nice idea to mix car and quadcopterconcepts. Why not a boat-quadcopter ?
+ Good yaw rate
+ Fast forward in quadcopter mode
+ Strong front leds
+ Good range control
+ Nice TX in the RTF
+ DeviationTX compatible
+ Good value for the price

CONS

- Is a real 6 axis stabilized quadcopter ?
- No ball-bearings (direct constact/friction between metal shaft and plastic house guard)
- Requiring regular shaft inspection parts (to check if blades are spinning normally), especially after a crash
- Noisy (a direct consequence of the absence of ball-bearings)
- Not proportional steering
- Not returning fast in steady hover after FFF


This quadcopter have been courtesy provided by Banggood in order to make a fair and not biased review. I would like to thanks them for this attitude.

You can find it at:
http://www.banggood.com/JXD-389-2-in...105842201212FRYou can find it actually for 47 USD at
Last edited by SeByDocKy; Oct 08, 2014 at 09:50 AM.
Sign up now
to remove ads between posts
Jun 03, 2014, 10:08 AM
Registered User
SeByDocKy's Avatar
Thread OP
Reserved for mods and videos

JXD 389 "flyingcar" outdoors test (Courtesy Banggood) (7 min 52 sec)


The excellent review of Flyin' Rian

Jin Xing Da - JXD389 Flying Car - Detailed Review and Indoor Flight (8 min 35 sec)


and this other one

The Arctic Cat Wildcat Trail Meets the JXD 389 Flying Car (10 min 33 sec)
Jun 03, 2014, 10:11 AM
Registered User
'eh, neat. ...but, I'd like to see a bearings on a rig like that, for that price. Bushings would have brass or teflon/nylon even been better.
Jun 03, 2014, 10:14 AM
Registered User
SBD, can you set the car for 100% rates, go as fast as you can in a straight line, hit the "Run/FLy" button without lowering throttle, will the quad activate and do a rolling takeoff?
Or, do you have to arm the quad after you change to "fly" mode?
Jun 03, 2014, 10:27 AM
Registered User
SeByDocKy's Avatar
Thread OP
Quote:
Originally Posted by EhnTeePee
'eh, neat. ...but, I'd like to see a bearings on a rig like that, for that price. Bushings would have brass or teflon/nylon even been better.
1000% agree .... What's a pity . The shaft's diameter is small (~1-2mm) so it need some 2mmx4mmx2mm ball-bearings. Unfortunatly, the housing won't allow you to install Ballbearings
Jun 03, 2014, 10:28 AM
Registered User
SeByDocKy's Avatar
Thread OP
Quote:
Originally Posted by EhnTeePee
SBD, can you set the car for 100% rates, go as fast as you can in a straight line, hit the "Run/FLy" button without lowering throttle, will the quad activate and do a rolling takeoff?
Or, do you have to arm the quad after you change to "fly" mode?
i) I have to try

ii) No you don't need to arm the quad .... so It can work maybe
Jun 03, 2014, 10:29 AM
Registered User
Gah....
Jun 03, 2014, 10:30 AM
Registered User
Quote:
Originally Posted by SeByDocKy
i) I have to try

ii) No you don't need to arm the quad .... so It can work maybe
Get on that!

It would add a new dimension to the flight operations as a flying car should be able to transition to and from flight mode, while still moving.

Jun 03, 2014, 10:32 AM
Registered User
SeByDocKy's Avatar
Thread OP
Quote:
Originally Posted by EhnTeePee
Get on that!

It would add a new dimension to the flight operations as a flying car should be able to transition to and from flight mode, while still moving.

What I did also ... is to race the car with the quad's throttle , I mean only by playing with the left throttle and F/B right stick. That's fun
Jun 03, 2014, 10:36 AM
Registered User
Yes of course.
That is a good news, I imagine it get's pretty crazy when you give it a lot of input.
Jun 03, 2014, 10:38 AM
Registered User
SeByDocKy's Avatar
Thread OP
Quote:
Originally Posted by EhnTeePee
Yes of course.
That is a good news, I imagine it get's pretty crazy when you give it a lot of input.
Yes ... but you need to train in these very low-riding conditions
Jun 03, 2014, 11:14 AM
Registered User
Thanks for your review
enough power for lift a mobius?
Jun 03, 2014, 11:25 AM
Registered User
SeByDocKy's Avatar
Thread OP
Quote:
Originally Posted by Chrisprolls
Thanks for your review
enough power for lift a mobius?
I don't think so ...... Maybe if you sacrify the car part ... you can save 10-15g...
In this case, maybe but really not sure
Jun 04, 2014, 11:25 AM
Registered User
SeByDocKy's Avatar
Thread OP
Ok .... I corrected a small error in my Devo config file and now Flips are working
Jun 04, 2014, 12:59 PM
Registered User
SeByDocKy's Avatar
Thread OP
I removed the car part in order to save some weight (10.7g but maybe 2-3 extra grams can be saved). Of course the quadcopter become much more sportive .... real challenging. I performed a new outdoors test with my nanotech 750 mAh lipo... I was able to fly > 9mm without problem. Be aware that motors become hot (due to some small friction in the gear setup)

By the way, I am really wondering if this quadcopter is 6 axis .... coz the 389 is absolutly not steady hover when releasing right stick. If you throw it in the air ...it won't stabilize itself when you push throttle .... Very strange situation coz the 389 got a 6050C chip


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product Jxd 389 Flying Car Quadcopter SeByDocKy Mini Multirotor Drones 49 Jul 23, 2015 02:12 AM