Maiden Test Flights for a South Carolina Arducopter

 

The sun was out, the winds were light, the temperature was about 85F, it was my birthday. There was nothing else to do but discover if all the time, money, energy, planning, and hope would work out.

It was a qualified success! Qualified in that I think pitch is reversed but in the case of today's short effort, it was another event of discovery on the road to longer flights.

 

 

The good news was I did not break a prop! The casualty of the trials was a leg! Anyone out there want to report how the stock 3DR legs break? They do sell spares at the store so I suspect one or two have failed.

 

 

The leg breaking may have been encouraged by the tether arrangement. The quad was blown while the line was taught and circled into the yard while I lowered the throttle. It impacted on the leg sideways moderately hard. The ground was wet and the toe stuck in the dirt while the copter kept rotating. The break was where one might expect it, at the through hole for the cross brace. If it had been on the driveway, I suspect it would have just skidded.

From my previous blog posts you would have known that while cutting legs out with my home brew CNC mill, I made plenty of extra legs. 10 minutes on the bench later and the Arudcopter was ready to go again. Unfortunately it was time to pack up and go see the grandchildren.

The tether weight was an old lamp ballast I use for a glue weight. I didn't think the copter could drag it anywhere especially with the small 'purple' motors (3DR sourced).

While driving to Tennessee to see the kids, it occurred to me that some sort of telescope/tilt platform would be a good tool for a copter-in-adjustment. All too often I read posts of noobs like me wanting to blame the APM or code for a setup issue. I suspect some form of gimbal jig to allow a tethered hoover would confirm if a command axis is reversed.

Throttle was good with liftoff around 52% of stick. Yaw seemd correct but the tether would yaw the quad when wind blew it to the rope end.

All in all, I am pleased and it was not a bad way to spend my 54th birthday.

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Comment by Carl La France on August 10, 2012 at 8:22pm

Congratulations R.D. Happy Birthday! The tether looks kind of long for a first flight I thought it might  only be allowed to get a few inches off the ground on it's first flight (not any higher than it could go to be able to  tip over )

54 you are just a chick I wish I was 54 again (and know what I know now! )You will get the bugs out of it Have a

Great Day!

Comment by R. D. Starwalt on August 10, 2012 at 8:32pm

Thank you Carl. When I figure out how to edit video, I will post a montage. Except for the bench shot, the other two pics were frame grabs.

It actually got up to about 6 ft height but with the breezes it would reach the tether end and start a yaw or roll. You could hear the motors pitch/speed change as the APM tried to maintain orientation in Stabilized mode.

I have since downloaded the logs and have been looking them over for clues to determine if Pitch is reversed.

GN!

Comment by Carl La France on August 10, 2012 at 9:40pm

If the pitch was reversed wouldn't it fly itself into the ground? I am not a Quad guy so I am just throwing it out there?

Comment by John Campen on August 11, 2012 at 12:58am

i often fly my copters in my lounge room to test them and play around with the PIDs. The pain is having to change batteries all the time. So I was thing about using a power adapter and a wire ruining to the copter in the same way I see that you have a tether fitted. First when I saw your picture that what i though it was. 

I built a system to suspend my copters to test the axis and yaw using my wife clothes rack. http://www.youtube.com/watch?v=ri0n3UVbC9s

Comment by R. D. Starwalt on August 11, 2012 at 5:45am

Monroe - thank you! One idea always leads to another. I was thinking of a pole inside a larger pole for vertical extension. Slotted and pinned to prevent rotation. The top of the pole would have the caster/gimbal for rotation and tilt. When at rest, a double plate would make the copter level. Check out John's video for a simple solution.

Carl - perhaps I too have the term incorrect. On a traditional RC heli, the actual throttle is pretty much wide open or off. The lift postive/negative is done with the rotor pitch. Most of them are set up to provide neutral thrust at the middle of the stick setting - hover if you will. The 3D copters actually reverse the thrust when the stick is moved below neutral. Weird to imagine, easier to feel on a sim.

In my case, the better description is 'elevator' seems reversed. If I wanted to go forward, it went backward. Thus the need to have a gimbal/caster to allow confirmation of a control without the terror of cracking it up.

John - Those are simple and clever ideas using what you have. I like it! Thank you for the link. There is plenty of lift to pull a cable and if the connectors are secured, the ground battery idea is great. The actual flight battery could still be on the copter. The cable secured at both ends could tether it. A normal deep cycle lead acid battery would provide long events of terror and bliss.

Comment by John Campen on August 11, 2012 at 7:23am

Ok RD, no sooner said than done. I have now set up my battery charger power supply unit with a cable long enough to supply power for my small quad copter for inside testing. This will save the life of the batteries as well avoid the hassle of swapping them over constantly for when doing PID tuning etc. Only thing its not powerful enough to fly my X8 quad and trips the over load at about 29amps. Ill try see if ii will run my hex next. Here is the video of the small quad run           

http://www.youtube.com/watch?v=PM4oZEulyqg&feature=youtu.be

Comment by Bob Wilkinson on August 11, 2012 at 9:55am
You should be able to use the mission planner radio calibration page to check if you have a channel reversed. The pitch and roll bar graphs should follow the sticks (up when you push up, down when you push down, same for left and right). If they go the other way you need to reverse them at the tx.

What radio are you using? I have dx6i and I did have to reverse something (don't remember off the top of my head but I could check).
Comment by R. D. Starwalt on August 11, 2012 at 1:11pm

DX6i here also and I do remember running the radio cal and noting the directions moved as indicated on the cal screen, Bob.

I may try to hang the quad from a tree limb to make sure it behaves properly.

The next quad will have hard points for just such testing. This quad is my trainer.

I won't complain about her weight if she doesn't complain about my flying.  ;)

Comment by Carl La France on August 11, 2012 at 1:59pm

R. D. !  "long events of Terror and Bliss!"Sounds like the marriage to my first wife who was 16 years younger than me , When you came home and opened the door you didn't know which way it would go? I see you re getting sound advise from people "In the Know" Good Luck and you Guys have a Good Day!

Comment by Jon von Weymarn on August 13, 2012 at 12:27am

I had one of my 3RD legs break in the exact same location. It happened when the earth suddenly attacked my quad with high speed...

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