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Friday, August 10, 2012

Hobby King i86AP 3-Axis Flight Stabilization – Flight Review

UPDATE  8/3/2012:  I learned that the Elevon jumper setting on the board causes the i86 to do your Elevon mixing for you.  So you have to turn off transmitter-based Elevon mixing or the two will cancel each other out.  It’s a nice added feature for people without computer radios and the mixing works very well, to include burning trim through properly to the control surfaces.


After Mike W. pointed out that Hobby King made Z83X cheaper, I immediately ordered a few boards.  Thanks for the tip, Mike!

Unfortunately, Hextronic charged my card but didn’t properly relay the payment status to Hobby King, so they didn’t send the board for 2 weeks.  Maybe it was an “error of convenience” since the boards went out of stock the day after I ordered, delaying the reshipment.  I think it is more likely that Hextronic just messed it up, since the same thing happens with about 1 in 5 orders in my experience.

At any rate, the boards are here.  Each 3-axis 8g board weighs the same and costs 45% less than a single-axis GWS PG-03, which currently form the basis of Z83X

GWS PG-03 based Z83X totally dominated AS3X in my head-to-head competition.   I’m anxious to see if HK’s version can do the same at 1/4th the price.

HKFlightStab

1

The i86AP instructions live here



On the Ground:                                                                        

Manufacturer Listed Features:
- Normal, flying wing (delta) and v-tail aircraft  selectable by jumper
- Supports 3D flight without undermining stability
- Independent gyro gain adjustment for aileron, elevator and rudder
- Functions including stick centering and gyro reversing
- Compact and light weight design
- Allows for mounting in the smallest of aircraft

Specs:
- Input Voltage: 4v to 6v DC
- PWM Output: 50Hz, 1020-2020us
- Gyro scale:
+/- 1000dps
- Gyro sample rate:
1KHz
- Operating temp:
-40° C to 85° C
- Size:
30mm x 40mm
- Weight:
8g

Required:
- 3 x male to male servo leads

Paid:
$18 (click for link)

In the Air:                                                                            

My recent flight review of the Parkzone Albatros received an overall F, mostly because of its wild ‘n wacky price tag.  But another reason was it’s sloppy ‘n sloshing adverse yaw combined with a lack of appropriate rudder effectiveness.  What luck!  The sloppy/sloshing part lends itself perfectly to this Flight Stabilization review. 

There are some solid aerodynamic solutions for adverse yaw which I suggested Albatros owners pursue, but instead of dialing them in to the Z8RC Ablo right away, I decided to add the new Hobbyking Flight Stabilization Board first.  This way, the i86 board is the only variable in a plane that desperately needs firm guidance.

AlbatrosInstall
The bad thing about using the Albatros is its iron chastity belt, making it impossible to open the plane and tune HK’s i86AP board in the field. 

The newer, even less expensive OrangeRX flight Stabilizer comes with a case, making it possible to mount the gain dials in an externally accessible way for flight test.  It also has a set of gyro reversing switches, but no apparent Elevon or V-Tail mixing:
OrangeRX Flight Stab

My 5 day old i86 board is already outdated!

The i86 board is simple to install and use.  It would be equally simple to pick up and move from plane to plane, already making it a Horizon Hobby AS3X killer, much like GWS-based Z83X. 

Contrary to Horizon Hobby propaganda that AS3X is a techno-miracle that took years to create and tune for RC, installing a 3-axis system could not be simpler.  You simply stick it in any plane with double sided foam tape (two pieces of devilishly sticky double-sided 3M tape are included in the i86 package) and fly.

The only tricky part of the installation that I discovered was my initial hookup of the rudder channel only, to make sure everything was functioning before hooking up the second two channels.  That didn’t work.  Apparently, the i86 board needs power to all three channels before it operates, so an in-plane one or two axis implementation might need a Y connector or two. 

You stick the board in the plane with the white arrow facing forward, then you connect the aileron, rudder, and elevator channels from your Rx to the board’s “in” pins using three male-male leads (40 cents apiece).  Then you plug the servo leads into the board’s “out” pins.   Servo signal wires (lighter in color) go on the top pin of each connector.

Done!

Unlike featureless AS3X, the 8g aircraft transferable i86 board provides gain controls for each axis and has the ability to do Elevon and V-Tail flight stabilization via jumper selection.  Since this was my first Merry-Go-Round ride and the aircraft is conventional, I left everything in the default position.

Result – perfect performance, first try.  Accuracy couldn’t have been better and there were no glitches.

Horizon Hobby’s one plane use AS3X is officially obsolete.  

With default gains set, directional stability of the PZ Albatros was significantly improved in every needed way: 

  • Yaw stability was better controlled
  • Nose-down tendency (from the nose heavy config) was muted when thrust faded
  • Hard stall breaks were better contained

I think the default gains are just about perfect for most applications.  The Albo, OTOH, could use more yaw stability, so the next time out I’ll gain the rudder up. Here is the first i86AP Albatros flight video:





The HK i86AP Flight Stabilization Board gets an
A+
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