• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

[Build Log] QAV250 CF edition

nilsen

Senior Member
#1
Hello everyone,

I have long marvelled and wished for my very own mini-quad since I am normally into the much larger aerial photography platforms.
Since I am the only RC flyer I know here in Switzerland I sent an email to some of my friends with links to some of the best FPV videos (charpu, juz70) I could find and asked "does anyone want to race mini-quads".
Surprisingly I had 2 takers and since they both have 0 experience in RC I thought this was going to be tough.

For christmas I got each of the 2 a Hubsan x4 and said "practice every waking moment" and they both obliged.

Anyway, eventually the parts arrived from getFPV and we got to building.

Here is my build log, I'll add to it as we finish and eventually, hopefully, fly.

I like a neat build and certainly shared my opinion with my mates who also saw how pretty these machines could look so we took a lot of time doing things slowly and meticulously (wrapping all the cables took a LOT of time.)

PDB with covered wires. This is the first step.
hex.jpg


This is for the LED's in the front and rear
hex-2.jpg


The frame itself is beautiful, light and strong.
hex-3.jpg


The first time this guy lifted a soldering iron.
hex-4.jpg


The PDB on the frame (my lovely wires are waaaaay to long :) )
hex-5.jpg


LED's
hex-6.jpg


ESC servo cables nicely wrapped up.
hex-7.jpg


hex-8.jpg


hex-9.jpg


hex-10.jpg


This is how it all fits together.
hex-11.jpg


hex-12.jpg


hex-13.jpg


My friend chose purple a his wire covering. It's a popular colour.
hex-14.jpg


Tonge out at an angle to get that screw.
hex-15.jpg


Motors on, receiver in.
hex-16.jpg


I was able to complete mine, my friends still have some time to go, they stopped at the motor part.
hex-17.jpg


hex-18.jpg


hex-20.jpg


hex-21.jpg


hex-22.jpg


hex-23.jpg

So my thoughts on the build.

1. This was the first miniquad I have seen and touched, I had NO idea they were that small.
2. The motors (2208 2300kv) are so tiny, I mean I can best describe them as "cute"
3. It's a slight challenge fitting everything, you have to cut all the cables to make things fit.
 
Last edited:

nilsen

Senior Member
#2
Next is the tuning and the software.

Naturally I flashes the naze with cleanflight and opened the juz70 video in youtube where he kindly shares all of his PID's.
Set the PID's and make a first flight.

Flips instantly.
try again.
Flips instantly.

ahhh, board orientation.

Set correct board orientation and this thing is like a stone sitting in the air. So incredibly solid, I am truly amazed. I haven't ever seen something just hang in the air like that, not even my huge hex is that stable.

The last thing I need to do is setup the FPV gear and get my mates setup and we'll go for some flying.

On a side note, I set profile 3 to the same PID's as those taken from the video and which I really enjoy flying with and tried out autotune. The results were surprising and were more aggressive than I expected. The autotuned PID's are a lot more fun to fly so in this particular example it worked out well.

Before:
Screen Shot 2015-01-19 at 13.54.50.png


After:
Screen Shot 2015-01-19 at 23.28.34.png

Coming from APM it's interesting how much difference small changes in PID values make.

I look forward to trying PID_Controller 1 but that is for another day.

Cheers!
 

nilsen

Senior Member
#6
Thank you Twirchity, I can't wait to fly this FPV through some trees and into the ground :)
You were the one who first showed me the concept of paracord sleeving and I now use it everywhere.
 

nilsen

Senior Member
#7
Sorry if it's a bit lame but I am really facinated by the size comparison, so I shot some size comparisons between my current biggest hex and the qav 250

For a size comparison...

Motors

From Left to right;

3525-850
2206-2350
4225-390
mini.jpg

Props;

13x38
5x38
??? - I'll use 15x60 on the very large hex
mini-2.jpg


Another Prop shot
mini-3.jpg


The mini-quad motor is a little more forward than the other two.
mini-4.jpg


Here the QAV is sleeping under big brother's legs
mini-5.jpg


From the top
mini-6.jpg


On Top
mini-7.jpg


Anther gratuitous prop shot
mini-8.jpg


Bye
 

nilsen

Senior Member
#8
So I would like to give an update on this little project.

Firstly my mates loved the damn things, haven't flown FPV much however one of them ended up in a lake on the 3rd flight as the owner thought that the sunset over the lake would make wonderful footage.
It's gone, "something went wrong" and it dropped right into the water :) Very very sad and I don't think he'll be re-investing. I think I will get all of my other friends together to pitch in and get a new one, although this time a cheaper frame and parts :)

Secondly I have been absolutely loving it, honestly I can see why the whole mini-quad hobby took off so quickly but when flying on Sunday my beloved qav took a hard fall and I broke an arm :(

I wasn't doing anything, just a full throttle run and all of a sudden it freaked out completely and just fell from the sky.
This is in rate mode by the way.
Here is the video


Any idea what could have happened?

Anyway, here is the damage.

Crash-1.jpg

Crash-2.jpg

Crash-3.jpg

Crash-4.jpg

While I wait for a replacement base plate I will try and repair it using a piece of aluminium. I'll keep you all posted.

Cheers!
 

HawkMan

Senior Member
#10
So I would like to give an update on this little project.

Firstly my mates loved the damn things, haven't flown FPV much however one of them ended up in a lake on the 3rd flight as the owner thought that the sunset over the lake would make wonderful footage.
It's gone, "something went wrong" and it dropped right into the water :) Very very sad and I don't think he'll be re-investing. I think I will get all of my other friends together to pitch in and get a new one, although this time a cheaper frame and parts :)

Secondly I have been absolutely loving it, honestly I can see why the whole mini-quad hobby took off so quickly but when flying on Sunday my beloved qav took a hard fall and I broke an arm :(

I wasn't doing anything, just a full throttle run and all of a sudden it freaked out completely and just fell from the sky.
This is in rate mode by the way.
Here is the video


Any idea what could have happened?

Anyway, here is the damage.

View attachment 43447

View attachment 43448

View attachment 43449

View attachment 43450

While I wait for a replacement base plate I will try and repair it using a piece of aluminium. I'll keep you all posted.

Cheers!
This is the main drawback of the QAV where the Emax250/Nighthawk copies are better. all the arms are part of the main bottom plate, so you need to replace all of it when at arm breaks as opposed to just the arm.

of course, usually the arms don't break since they really take a beating. But as happened here, sometimes it happens.
 

jipp

Senior Member
#11
ouch, nice build. t o bad about your friend who lost his to a lake.. man i would need a lot of flying experience and know for sure my quad was working 100 percent with zero bugs before id try to take a fly over water. but i live in the desert so finding water here takes work. :D
chris.
 

nilsen

Senior Member
#12
Yeah I know, he was devastated and cried, his girlfriend laughed hysterically and said "well you're the idiot who flew it over the lake". I think he knows his mistake :)

Anyway here is the fix attempt, will see if I can take it for a flight later to see if it holds up.

Crash-1.jpg

Crash-2.jpg

Crash-3.jpg
 

jipp

Senior Member
#13
should hold up till you take another hard crash. yeah, i could see people laughing at me for being stupid.. sometimes thing sound good at the time.. not so much in hind sight. heh.
chris.
 

Kanifee

Junior Member
#14
I feel your pain, I'm on my second baseplate and have just cracked that one. Admitidly this looks to be a hairline crack in the top layer and the arm is still rigid but the last one I cracked 2 and broke one like yours. I guess that is what happens when you fly these things hard and the ground catches up to your faster than your flying skills can.

Im thinking about investing in a blackout mini H quad but I love the lumy frame so much!

I would fly with caution for a bit and not too high, it may well have been a esc that overloaded or some sort of faulty joint maybe? certainly looks like a one motor failure the way it fell out of the air.
 

nilsen

Senior Member
#15
Oh wow, number 2 already. I thought they were indestructible however the force during one of those crashes cannot be underestimated.

Anyway I took it flying yesterday and thrashed it on 4s, it handled like a pro, the fix seems to be holding up. Maybe I'll keep the extra baseplate for when it's absolutely necessary to replace it.

I think so too, I think an ESC cut off but the thing is after that crash I tested everything and it ran flawlessly. It could be something just overheated from the full throttle run.
 

Kanifee

Junior Member
#16
Glad to hear it was all Ok, the first crash I had was a massive one, not very high but it was at high speed and landed belly down in a dip, I think the arms met ground before the belly so a lot of stress on arms indeed.
The second I think really shouldn't have cracked the frame but I have read a couple of forum posts that state luminier may have changed the CF on the later frames as the earlier ones did indeed seem more rigid. Maybe the demand in numbers out stripped the stock a particular vendor could provide the carbon fibre in.
 

nilsen

Senior Member
#17
Oh that would be a real pity if they are now shipping a lower quality product.
Maybe replaceable arms are the way forward, I don't know. The QAV is just so pretty!
Maybe G10 is way to go for the base plate alone.
 

nilsen

Senior Member
#19
I wanted to share a small flying montage from my first flights after fixing the focus on my Xiaomi Yi.


Incidentally after fixing the focus the camera performs surprisingly well, compared to my Gopro Hero 4 Silver it's not quite there but it is way better than the mobius.
 

nilsen

Senior Member
#20
Hello All,

I reflashed the ESC's with BlHeli and took the opportunity to do a bit of a rebuild with the replacement frame.

I made a build video, be aware it's 12 minutes long but maybe some of you will enjoy it :)

Cheers!