Over two years ago when I first tested DJI’s XP3.1 I sent them some feedback on a wish list and thought it was just that; a wish.  But DJI listened to the masses and the replacement for XP3.1 was born. 

My initial reaction upon opening the box was “Wow, that’s small!”  Ace One is one third of XP3.1’s weight.  That is a considerable amount of weight reduction which translates to more flight time.  Each component's size is substantially smaller compared to XP3.1’s.  The size and weight allows Ace One to be installed into smaller helicopters.

The main controller is just slightly bigger than a Futaba 14 channel receiver and now has more inputs and outputs.  DJI got rid of the serial connection and is now using CAN-Bus and micro USB connections.  This also changed the weight of the cables that added to the weight lost. 

With XP3.1 the IMU and barometer was originally in the same housing as the main controller but it is now separate which allows for better placement.  XP3.1’s main controller came with an enclosure that included dampers to absorb vibrations.  Not to forget to mention it also increased its sized that made finding a location sometimes difficult.  With Ace One’s IMU the damper is built inside.  Again, this adds to the additional weight lost and size.

Ace One’s built-in tail gyro works like a charm.  It holds rock solid.  I remember having to test out various gyros for XP3.1.  Of course it wasn’t consistent as performance varied from one manufacturer to another.  Having a built-in tail gyro resolves this consistency issue while maintaining control over its programming.  Setting it up on the software is even easier.

Ace One’s GPS has been redesigned to include the status LEDs that was separate in XP3.1.  It’s smaller and more aerodynamic compared to XP3.1’s box shape GPS housing.

Unfortunately I was not able to test out the built in engine governor for this review.  If I get the chance to test it then I will update this review.

DJI completely redesigned the configuration software; it’s feature-loaded!  The Ace Assistant is easy to install and use.  Installing their provided USB driver works on the first go; XP3.1’s serial connection gave some users a difficult time with drivers.  It connects with the Ace One as soon as the USB is plugged in.  No more “connect” button. 

Future wish with the software and driver would be support for MAC users.  I’m sure many would appreciate this.

A new feature that everyone welcomes is the addition of flybarless support.  This was a long anticipated feature.  DJI made it easier to configure by adding a Remote Adjustment feature.  No more taking off, land, adjust and take-off again.  Simply adjust on the “fly”.  One thing I do have to mention is you should spend the time to make sure your flybarless gain settings are perfect for your flight preferences.  I used the suggested parameters as a starting point and adjusted accordingly.  But I made the mistake of not perfecting the gain settings that later on affected the auto pilot during test flights; lesson learned.

At first I was uncertain on the benefits of the various flight modes when I first saw them.  But after having the chance to play with them I’m finding them very useful. 

The ATTITUDE flight mode was already in XP3.1.  The difference between the two is Ace One resists drift.  What I mean is with XP3.1, when you push the cyclic forward, the helicopter will remain upright but will continue to drift.  This was actually a nice flight characteristic for shooting videos as the helicopter will naturally drift, without any input, giving a nice smooth shot.  ATTITUDE mode is specifically designed for when GPS position hold is not required or when GPS signal is weak or non-existent yet still stabilizing the helicopter without the fear of rolling over.

GPS Cruise flight mode is most useful when a specific flight speed is required.  Set-speed is achieved at full cyclic.  For example if you set Max Speed Limit to 15ms (or 54Km) then when you apply full cyclic the helicopter will fly at a maximum speed or 15ms.

GPS Attitude flight mode is for photographers that want to lock the helicopter at one position and altitude and shoot.  You can fly around in this flight mode but you will have to maintain your own speed. 

System Check was slightly improved from XP3.1 with the ability to reverse direction.

As shown in the Trex700 videos, in the gallery section, position hold works as claimed.  I admit I did not spend the same amount of time configuring after installing PhotoShip One’s 3XPro V2 camera gimbal.  The gimbal was installed two days prior to shooting the videos.  The change in weight will affect the auto pilot’s performance.  It’s simply adjusting a few gain settings to get it back on track.  You could clearly see this in the position holding test video where the helicopter was drifting within a 20ft area.  This is my fault; not Ace One.

The Auto Pilot gain settings also include the Remote Adjustment feature; again making setup that much easier.

Another wish by many users is the increase in speed.  Ace One now support speeds up to 72 Km or 44.8 MPH.  With regards to Ace Assistant speed settings I would prefer the speed settings are either in KM or MPH or have the ability to choose between different speed standards.  It’s much easier for the everyday person to relate to kilometers per hour or miles per hour than meters per second.  Hence I created and provided a speed conversion for this purpose.

Ascent and descent rates have also been changed where the user now has control; unlike XP3.1 where ascent and descent rates were controlled.  Climbing to higher altitudes is much faster now.   Of course this depends on overall weight.  I think I timed it, awhile back; climbing to 400ft took approximately 17 seconds with an overall weight of 15lbs.

Return-To-Home feature was added to both XP3.1 and Ace One.  It works as per their specs.  One thing I would like DJI to add is the ability to specify the altitude to fly home at and the hover point.  When the helicopter is below 30m (98ft) the helicopter will climb to 30m then fly home.  I think it would be best to have the option to specify this value so users can tailor their flights according to the location; just in case 30m is too low.

Proper setup of Center Position is crucial in transitioning between manual and auto modes.  If this is not setup properly the helicopter may change altitude during transition.  You want to fly in manual mode and record the hover percentage or pitch angle.  Then make this change in your pitch curve while at center stick.  If you changed the weight of the helicopter then you will have to set this again.

One thing to note is head speed will differ from an older pack versus a newer pack.  For example if you were to set the center position, with an older pack at your target head speed, changing from manual to auto modes will work just fine.  But if you were to change to a newer pack and fly in manual mode your head speed will be much higher.  So when you switch over to auto mode your head speed will drop to the saved value in Center Position.  This is fine; just something to watch out for.  But if you had Semi-Auto Take off/landing then you will not notice this change as the system will use the saved settings.

With regards to head speed I would probably want the option of being able to change head speed while in one of the auto control modes.  There are times when I wished I had a slightly faster head speed.  I don’t see how this can adversely affect the control modes as it’s only affecting the RPM and not autopilot control.

As I mentioned earlier, due to last minute decisions, I only installed the 3XPro two days prior to shooting the flight videos.  I was not able to get an onboard video displaying the gimbal stabilizing function of Ace One.  From the video, shot from the ground, you can visually see the camera platform stayed relatively leveled throughout the test.  I will add an onboard test later on.  Just remember if you are using the 3XPro, or any three-axis gimbals with the built in stabilizer, then you have to lock the pan axis. 

Camera operation can easily be separated from the pilot as shown in the diagram I provided.  I’m not sure if this is possible but if DJI could make it so the camera operator can be given rudder control when required.  This will take some practice between pilot and camera operator.  This will also eliminate the need for after market electronics.

A quick addition DJI can add to the Gimbal section is the option to enable/disable it.  Currently it is always on.  If you had to go back to your flybarless settings or auto pilot settings and had to use the remote adjustment feature the gimbal will also move as you are moving the slider/knob.  I do realize you could unplug the servos but sometimes that may be more work than required.  I think the gain settings may be getting affected while you are adjusting and the gimbal is moving at the same time.

Another option I would like to see is a separate pan axis stabilizer.  This is mainly for people that want to fully utilize a three axis gimbal.  This should be easy to accomplish as they already have the hardware.  This can be a totally separate hardware that does not need to be connected to the main controller but can still be programmed via USB.

Again, DJI listened; they added the ability to upgrade the firmware.  This was becoming expensive for XP3.1 users when a firmware upgrade was available as they have to ship the main controller back to DJI.  Updating the system firmware is simple with the Ace One.  Aside from their updates on their website DJI added a “Newsletter” function where they can communicate with their users.  Here they usually send a notice of any software or firmware updates so users are always aware of any changes.  Select Firmware Upgrade under the Tools menu; the software will connect with DJI servers and download the latest firmware.

Ace One can now be powered from the helicopter’s BEC.  This was a bit of a nuisance with XP3.1 as I would sometimes forget to fully charge the 2s Lipo.  This is an operational, weight and cost saving for the users.  A redundant power source can be plugged into any spare channel on the main controller. 

When accessing the flight log the one thing I wished DJI added is the Date Created and Date Modified file properties.  Sometimes when you need to send a specific flight log back to DJI it would be easier to locate if the file had a date and time associated with it.  You will notice how quickly the files add up.

Upgradable?  Yes, Ace One can be upgraded to various products DJI offers.  Upgrade path is Semi-Auto Take off/landing > Ace View > Ace View Keyboard/Joystick > Ace View Click & Go > Ace Waypoint.

Clearly DJI has done an excellent job with the Ace One.  With so many features jammed into a tiny unit, excellent performance, while maintaining a competitive cost; it’s an easy choice.  Given their history we can only expect more and more products and improvements in the near future with autopilots from DJI.

A special thanks to Advance RC - APV Canada, PhotoShip One and TSolutions for their contributions and assistance in making this review possible.  

Thank you! 

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