Happy Fathers Day to all the Dad's out there today!

I had a great day at the field yesterday with a new airframe, the Blitz RC Super Sky Surfer. With a 95" wingspan and a 6.25lb total weight fully loaded this is a big lazy plane! It has a cruising speed of apx 30-35 Mph and a duration of apx 15 minutes on two parallel 3S 2200mah batteries.

APM 2.5

uBlox LEA-6H


Attopilot 90A

MinimOSD v1.1

3DR 900MHz

Arduplane 2.73

I've been trying to tune the plane for better navigation, but I'm having some trouble getting it to respond crisply when flying a box in moderate winds. Yesterday there was a steady wind from the N-NE averaging around 8 mph and the orientation of the field runs N to S. The box pattern has WP1 to the South WP2 East from WP1, WP3 is North from WP2, and WP4 is West from WP3 closing the box. The segments from WP3-WP2 and WP4 to WP1 are parallel to each other.

When I enter Auto (about 50% of the way through the tlog) I start near WP3, the plane tracks well to WP1 then way overshoots, over-corrects, turns back on course to WP2 just in time to hit WP2 then slightly overshoots WP2 and turns back well on course to WP3. It reaches WP3 and turns well onto the course to WP3. The turn at WP4 is pretty good, then it wanders a bit on the way to WP1 in the tailwind. This is the pattern that is repeated for the rest of the flight till I exhaust the battery and need to land.

I have attached a copy of the tlog as well as a copy of the parameter file. Below are a few screenshots comparisons of roll speed during FBW-A Max Bank,roll speed during AUTO, roll to nav-roll during AUTO, Mission planner Way Points 1-4, and a Google Earth plot of the Auto portion of the flight including the Elevation profile.

Any feedback or suggestions on that I can do to improve navigation would be appreciated.

Screenshot from the MP with North at the top.

Google Earth View with Elevation profile. The arrow is at the start of the Auto portion of the flight. It maintains altitude fairly well with a deviation of around 50-60ft min to max. What can I do to tighten this up?

Comparison of Roll Attitude vs. Commanded Nav Roll. The first two left turns show a Nav Roll at max Bank of 50 degrees, but the Roll response is slow to reach Max Bank

Plot of Roll (value of 1=apx 60deg/sec) during Auto. To me it looks like the mean is about .5 which looks like I need to increase ROLL2SRV_P from .7 to perhaps .9?

Comparision of roll speed vs Bank Angle (max) during CW and CCW turns in FBW-A.......oops looks like I cut off the bottom of that pic! Oh well didn't lose anything important.

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I shall follow this with interest as I have set one of those up this week. As an aside, are you using the stock power setup and did you replace the spar which is almost heavier than my current airframe on its own.


No I am not using the stock power set up. What I didn't include in my configuration is that I have an FPV system with pan tilt camera. The plane is almost 2lbs over stock weight so I needed more power and a bigger prop. I would highly recommend the motor mount adapter from small parts cnc. This allows me to turn a 13" prop as opposed to the stock 8" prop as well as mount a larger motor. I'm using a Rimfire .32 with a Master Airscrew 13" x 8" 3-Blade prop on 3S at about 70 watts/lb. This provides enough power for me to takeoff from a well trimmed grass field without a problem. I might suggest a bit more power if you want any aerobatic capability and perhaps 4S would be nice.

I bought a pultruded carbon tube from goodwinds.com, but I'm still using the fiberglass rod supplied with the kit. I'm concerned about the strentgth of the carbon tube in an emergency. Even during landing, if the approach is too steep and I jerk back the stick to avoid a hard landing you can put a high g load and the tube perhaps 70lbs or more load is possible and I'm not sure the tube will sustain that. For normal flight, no problem. At 6.25lbs the plane flies fine on my current power setup so I'm not worried about the extra weight at this point. I would really recommend the motor mount adapter! The other thing I would do is replace the control rods to the Rudder/Elevator with  heavier gauge and use solder links at the control surface end to give you the needed length (you need about 37" and the rods come in 36" lengths).

Blitz RC Works Super Sky Surfer Adjustable Motor MountRegards,

Nathaniel ~KD2DEY

PM me if you want to talk more about it!

In the picture above, is the prop not on backwards?


Sure is! It's just a product shot from the website, I'm sure he didn't realize it when he took the shots.


Nathaniel ~KD2DEY

Nathaniel. Can't say I'm an expert but have you tried changing your RLL2SRV_I (Servo PID I) value any? I started off at Zero on my Skyhunter which flies about the same speed. I slowly brought it up by tenths of a value until I started seeing a difference. For the Skyhunter I stopped at 0.75. 

Now the SH will start the turn as it enters the waypoint bubble (20-30 meters). Before it'd fly through the waypoint marker before making the turn. I still need to adjust some of my L1 values after doing the changes to the "I" value. I'd like to get rid of some of the drifting I'm seeing after I hit a waypoint and I'm getting there. 

Either way you look like you have the L1 tuning down and just need to do some minor tweaks. 


Thanks for your reply! As of now I have only just begun to introduce any I term in the mix. Right now my I term is only at .1, so I'll try adding some more I in .1 increments and see how well that improves things.

Thanks Again,

Nathaniel ~KD2DEY

Sounds good! One thing I forgot to mention.. I set my Loiter Circle to 40-45 and my Waypoints to 30 to start with. It helps if you have the GCS and telemetry and can watch it it the bubble. In my experience you'll know you're close when you hit the edge of the bubble and you see the AFH bank to make the turn. From there you can narrow down the circle. Right now I'm down to 20 meters for my tight waypoint courses and 30 for my LONG waypoint courses. 

I will say it's nice being able to update things in real time! 


What's the span on your Skyhunter? How about wing area vs. weight? What do you mean by the difference between 'tight' and 'LONG' waypoint courses?


Nathaniel ~KD2DEY

Span is 1.8m, I'd have to go back and calculate my wing loading. and I'm coming in probably around 2000 Grams. 

I have one field where I can take the SH is a 2.5km by 1.5km field. Usually I do a bunch of my  testing at that field. Since I have more room to move around in out there I set my default waypoint sizes larger (30-40 meters). The other field I have is a AMA controlled field so I only have 600 meters by 150 meters to maneuver around in. I set my default waypoint sizes smaller at that field. 

Here's a flight I did after some tuning at started bringing up the "I" value. The wind out there was blowing a gusty ~24kph from West to East. Sadly my telemetry has about a 500 meter limit before I get packet loss. One reason why I want to get the AT working with a -8dBi patch! 

I just got one of the Blitz RC Super Sky Surfers today and am looking forward to moving my APM 2.5 over from a HK Phantom Wing to the Surfer. Should be an amazing bird for FPV. The Phantom is OK in calm air but has a weird yaw oscillation in strong winds. You don't even notice it from the ground but behind the goggles it's annoying. The Phantom has served me well but it's time to move on.

How is yours flying Nathaniel? Did you get it tuned out well? Hope you are still following this thread, will send PM.

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