Episode 4 : SK450 Dead Cat maiden flight with HackHD

Hey Guys,

I tested out my new SK450 Dead Cat quadcopter yesterday, with my HackHD onboard . I am running it using an APM 2.5 on ArduCopter 2.9.1.

I am testing Stabilize, Position hold and Altitude hold in this video. We don’t have a camera on the ground this time unfortunately, so only on-board video recorded by the HackHD is available to us. You’ll see some nice aerial views of the park where I was flying.

This is my first flight on this frame and all PIDs are all stock.

I added something, which is not a part of stock APM setup, a DIY 4 channel LED strip driver (only 3 channels in use presently), controlling LED strips on the arms to display ARMING and GPS status. Two long parallel strips on the quad’s bottom is present for night flying and orientation. The front arms have red strips (Arming status) and the rear ones are blue (GPS lock status). The bottom ones are pure white (not controlled by APM ; they light up on plugging in the battery) All the strips are excellent for orientation, especially when it starts getting dark.

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Setup :

  • APM 2.5 (no telemetry yet)
  • MediaTek 3329 with v1.9 firmware
  • SK450 + Dead Cat conversion kit
  • MultiStar 30A Opto ESCs
  • Turnigy Aerodrive D2836/9 950 kV motors
  • 10 x 4.5 SF propellers
  • HackHD (recording to microSD)
  • FS-TH9x with stock module and Rx  (FAILSAFE working!!)

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We reached a maximum height of 29m from the launch position according to the post-flight analysis of the flight logs and recreation of the KML file in Google Earth. Total distance flown was 150m.

The total flying time was around 9 min, but we could go another 5 minutes or so. I had a 10 min alarm set in ER9x to warn me to land. The video is edited down and we had some camera issues in the first liftoff, so a bit of footage was lost.

I had calculated the theoretical flight time with the help of xCopterCalc, which proved extremely useful since I didn’t have a battery alarm on hand or a Volt/Current sensor on my quad sending back data using telemetry.

Flight Performance of ArduCopter 2.9.1 :

Stabilize : Superb, very stable.

stab

Position hold : It drifts around a lot, and couldn’t keep it in position hold for long as it was going out of my view. Perhaps its got something to do with the GPS bug in AC 2.9. Should improve in 2.9.2 which will have inertial control on X and Y axes as well. PID tuning should get it a bit better though.

poshold

Altitude hold : Superb, best ever. The inertial control on the Z axis has done wonders.

althold

I am using a two stage vibration absorption and dampening system, (of which only one stage is actively working as of now) which gives me +/- 5  vibration on all axes. The second stage, which is supposed to have some Kyosho Zeal tape, is inactive at the moment and I have substituted it with soft double sided foam tape until I can get hold of some Zeal.

The first stage consists of small sections of the softest silicon tubing I could get (aquarium air hose). This coupled with Zeal tape, I think will be a far easier method than suspension using O-rings, etc. I belive that  this system has the potential to bring down the vibrations to atleast +/- 1 if coupled with Zeal tape or Align adhesive gel.

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Vibration graph from the flight:

vibr

Thanks for reading through!

Kabir

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One response to “Episode 4 : SK450 Dead Cat maiden flight with HackHD

  1. hey dude,
    beautiful post very rich.
    i’ve just finished to build a dead cat sk450 with an APM 2.5, but i’m coming from an X config, so i facing a forward drift at take off.
    can you please advice me about your pid configuration? i will very appreciate it. thank you in advance. dj

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