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1st flight....well sort of........
#1
Hello,

I have just finished my 1st build, an Alien 5", built as per Rotor Riots build tutorial, same equipment , not 100% sure about ALL the software/ firmware. It was a little hard to tell if the ESC firmware was the same, I don't think so, due to the release dates I noticed on the KISS website............so I must make the best decision I can with that one.....

I have installed KISS GUI 1.14,

 Ver. 1.1RC6 on the FC,

 And flashed the ESC's with ESC24A_108f..........I believe these to be the latest and most stable versions.........................I hope.................

Now before I do anything, I always run up a machine without props (or rotor blades in the case of my 60 size helis) just to try and catch any program issues that may cause a machine to suddenly lift off uncontrollably, that being said, when I powered up the quad for the first time, all seemed normal, the quad responded to my stick inputs as I would expect, motors spooling up and down depending on what stick commands were given.

All motors returning to "idle" when throttle was reduced to zero. (there may have been a small imbalance in prop speeds due the the fact I may not have nulled out any pitch or roll commands completely................but for the most part the props reduced their speed as expected.........

Fail safe tested and working normal

Now for the next test, props on, quad restrained from moving, by holding in place with arms ty-wrapped to a piece of small plywood, and the plywood held down by two cinder blocks:

I noticed when I armed the quad, that all the motors spooled up to a low rpm, nowhere near enough to generate lift, just enough to let you know the quad is working, motor #4 was idling noticeably slower than the other 3 not a ton less, just enough to know it was less than the other 3, but once throttle was increased, #4 came up to speed with the other 3......as near as I could visually tell anyway.

So my 1st question is this, the fact that motor 4 was idling a little slower than the other 3, is this a cause for concern ?


And my 2nd question is a little more unorthodox, having watched many videos of people "hand launching" and "hand retrieving" their quads, I felt safe holding the quad firmly in my hand (wearing leather work gloves and my arc flash face shield, Yea I know, maybe a little carried away, but one can never be too safe........!!)

Anyway, with my wife holding the TX a safe distance away (level mode on) As the throttle was advanced, the quad started to spool the motors up and down in a very wild and concerning way, that caused me to go "what the heck is wrong !!" like it was trying to fly off in any direction............................

I put the quad back on the bench, removed the props and ran my "pre-tests" again, everything was back to normal, behaving as I would expect............OK, so now I'm a little confused.........which is very easy for me.................

After I sat and thought about it for a few minutes, I had the following thought:

Because I had the quad in "level" mode, and I was not holding it level, was the gyro trying to compensate for me not holding it level and the more I moved it, the more the gyro was trying to bring it back to "level" ???????

Thoughts...................

Or should I buy a book on needlepoint..................

Thanks
Danny
#2
When you give some throttle, You activate the PID loop, which again will make your motors spin up. There will always be a small error when on the ground, and since the I-term is dependent of time, the I-gain will increase, making the motors spool up. If you have activated airmode, you will see that when releasing the throttle, the motors will still spool up. this is perfectly fine, because as soon as the quad is in the air, it will behave just normal. Airmode is very nice to have on when you start flying a bit more acro, as you will still maintain control of the craft at zero throttle. it is nice to have in dive situations.
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#3
Thank you for the reply, I do not even pretend to understand the PID loop yet, I will be hitting you tube hard and heavy to hopefully get a BASIC understanding of it and how it affects the quad, good to know I dont need to worry about motor 4 being a little slower on the ground

Thanks again !!!
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#4
Oyvinla explained it quite nicely.  The only thing I would add is to go ahead and get the book on needlepoint......you'll find it a great stress reliever when mulling over that equipment or flying problem you haven't quite solved yet!!! Big Grin Big Grin Big Grin
"Damn the torpedoes!!!  Full speed ahead!!!"
[-] The following 1 user Likes sirdude's post:
  • sloscotty
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#5
lol, I will take your advice on the book !!!!!!!
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#6
This guy explains the PID loop quite well:
[-] The following 2 users Like oyvinla's post:
  • DannyZ, Grisha0
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#7
Great video, thanks for sharing..............................I will try to put the info to good use !!!!
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#8
And for tuning your quad, my best advice is to check out Joshua Bardwells youtube videos about the topic.

[-] The following 1 user Likes oyvinla's post:
  • Tom BD Bad
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#9
Thank you for the great vids, they are very informative !!!!!

I will let you know how the maiden flight goes, when we get some flyable weather here in the northeast !
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