Servers by jDrones

Skywalker X8 Quadplane Build 4

skwalker-quadplane

(darrell) #1

Almost two years ago I posted about my first adventures with building quadplanes. I’m up to my fourth build of a Skywalker X8 quadplane now having tried a few different approaches.

This time around I wanted to move from using slower vertical motors with large props, such as I would use in a multirotor build, to smaller faster lower voltage motors with smaller props. I’m still using separate power circuits for the vertical and forward motors to ensure I always have enough battery power left to land with. I did have to upgrade the wiring to handle the additional current required by using 4S rather than 6S batteries for the vertical motors.

I’m also staying with wing extensions rather than under the wing mounting of the motor bars. The next few weeks I’ll be doing some flight tests of auto missions and testing how long and far this build will go. Here are the components I used this time around.

  • Single HobbyKing graphine 5.0A 45C 4S battery for vertical motors
  • Mauch current monitor. 60A draw during hover, 90A peak.
  • Approximately 5 minute flight time
  • Single or dual HobbyKing Multistar 8.0A 10C battery for forward motor
  • HobbyKing current sensor
  • 14 Amp current draw during cruise with 40 amp peak
  • Forward motor – HobbyKing SK3 4240-740kv
  • HobbyKing 85A ESC
  • 13x8 forward prop
  • Vertical motors – SunnySky 3120-1100kv with 12x4.8 props
  • Droidworx multirotor motor mounts (designed for round tubes, modified for square tubes)
  • HobbyKing 60A Plush ESCs
  • Wing extensions. 180mm width. Allows for use of up to 15” props. Increases wing area from 80DM^2 to 96DM^2 – 980mm 15x15 square carbon fiber booms joined in the middle with a 12x12 aluminum insert to strengthen area that carbon spars pass through.
  • Digital air speed sensor mounted in 3D printed mount available from thingiverse.com web site
  • Custom balsa mount to fit Sony A6000 camera with 16mm lens mounted near center of gravity
  • Pixhawk 1 flight controller (upgrade to the amazing Cube if you can)
  • ArduPilot 3.9.8
  • Ublox GPS / Compass
  • RFD 9000X radio modem data link
  • FRSKY X8R receiver
  • Additional 5V BEC to Pixhawk power rail and to power Mach power sensor module
  • Wing tips connected with posts and magnets
  • Empty weight 5kg. MTOW 7kg.
  • Max flight time with two 8A batteries approx 60 minutes
  • Max flight distance ~60 kms
  • Cruise speed 18-20m/s – Stall speed 14m/s
  • Vinyl covering, same as used on cars
  • Wing tape on top and bottom of wings for additional strength
  • Elevons connected with hinges and tape
  • Elevons controlled with dual digital servos (one additional to stock airframe)
  • Two canopy latches added to rear of canopy

(RickyG) #2

Thats cool.
Your inspiring me.


(A. Murphy) #3

@Darrell nice job, you mentioned that you had separate power circuits for the vertical and forward motors. Are you saying that you have two separate batteries for vert and forward flight? Did you wire both to the pixhawk’s power module or just one or neither?


(juvinski) #4

Hi @darrell and @Airpig,

I’m looking for an alternative to https://www.foxtechfpv.com/pg20-dual-battery-swapping-board.html
to use 2 batteries and switch the power between 2 batteries on a quad plane, do you know something ?


(gmorph) #5

Very cool. Love all the detail - extremely useful.


(darrell) #6

Yes, two totally separate power circuits. I have two 8A 10C batteries in parallel for the forward motor connected to a Pixhawk power module and a single 5A 45C for the vertical motors connected to a Mauch 100A power module. Both power modules are connected to the Pixhawk so I can monitor voltage and current.


(darrell) #7

Actually, I looked at that same switching device and it’s the only one I know of.


(Luís Vale Gonçalves) #8

I believe that Mauch has something like that


(A. Murphy) #9

@luisvale that is what I thought @Darrell was talking about when he said a Mach 100A power module but I wasn’t sure. If you have separate batteries for vertical and horizontal propulsion do you actually need to have both hooked up, via a power module, to the FC? Can you have just the horizontial propulsion battery connected via PM and then just have the vertical battery connected straight to the ESCs, essentially just winging it in terms of knowing how much hover time you’ve got?


(Luís Vale Gonçalves) #10

I would still be using the 2 power modules and configure each according to its settings, because we want Failsafe to be triggered by different conditions on each one, and recent versions of Ardupilot allow the use of different settings for each power module connected


(darrell) #11

Yes, you are right. It’s not a requirement to have a power module for the battery used on the vertical motors. I’ve never actually referred to info it provides in flight. With vertical flight I know the time the battery will last from test flights and that it is good for two take off and landings, if they are quick. My goal with quadplanes is to get up in the air for transition to forward flight quickly and to land quickly. The less time in hover mode the better as far as I’m concerned.

I have the power module connected because I’m doing comparisons of different motors and I like to check the logs for current draw and voltage drop of the batteries. The more data the better.


(Anthony) #12

Currently, we are using the same setup and only have a power brick on the forward motor.

However, I am seriously considering installing a second power brick on the multi rotor part. It will give the following advantages:

  1. monitoring the health and condition of the multi rotor battery.

  2. have a secondary power to the pixhawk for redundancy.

I just recently learned the Cube doesn’t have redundancy from the servo rail which resulted in a serious crash. So to use the multirotor part to give redundancy would be a very good solution.