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TBS Discovery Pro Build

nilsen

Senior Member
#1
As some of you know, I recently built a QAV500 after breaking down my hex for parts and to be completely honest, I was never 100% happy with the QAV500 for 2 reasons:
  1. It was too big
  2. I was never able to get completely stable video footage as there were vibrations in the frame so the gimbal always twitched.

I don't attribute this to an inherantly bad design, I have always favoured the lower KV motors with larger props for longer flight time, but the larger the props, the more vibrations are present, even with balancing you will end up with some vibrations unless you fork out on top shelf components and then the costs quickly add up.

Another problem is that with large props things get quite floaty and unresponsive, for example, fliyng in manual mode with the QAV on the APM was so damn scary, that thing would bob all over the place and when flying forward and then stopping it would spin around and would give me a heart attack and make me keep my finger on the switch to return to "stab" mode almost all of the time.

The vibrations in the QAV were picked up by the imu on the gimbal and this translated to noise which would cause the gimbal to twitch. I don't know how many hours I spent tuning and re-tuning, the footage was never rock solid, even a DJI phantom 3 and at this stage I may as well buy one of them... BUT I love building so...

The QAV was sold and I was able to get back most of my money as I built it pretty well so now someone
Enter the TBS Discovery pro.

When I was looking at the QAV500 I was also looking at the discovery pro with the integrated Alexmos board, compact design I was quite intreigued but was not sold due to the fact tat it uses 900-1000kv motors with relatively small (9x5) props thinking that this would only give about 15 minutes flight time I put it aside however in reality I don't ever fly much more than 10 minutes when filming so it's actually not a deal breaker.

Please note that I have already built the Discovery and am now writing this for the enjoyment and benefit of others so I don't have many build pics but will post pics of the finished build later.

Parts:
TBS Discovery pro
TBS 1000kV "custom" motors.
KISS 30amp ESC's
TBS Crossfire - yeasssss!
Graupner 9x5 e-prop
TBS Boss 500mw Vtx
Pixhack FC

The build:
So this is a wonderfully designed product using the cheap DJI flamewheel arms it fits together nicely with the top and bottom plate connecting with the interconnect cable, the RX sits at the back of the craft and the signal is nicely transmitted though the board so no cumbersome wires.

The pixhack doesn't really fit too well without modifying the gimbal dampening arm but this itn's a problem, it fits the Naza much better.

I used the pixhack because the quality is excellent and more importantly the corssfire will natively support MAVlink and the RX could connect to a phone/tablet via bluetooth which does away with any additional 3DR radios for telemtry which is a dream come true.

I'll post pictures later.
 

nilsen

Senior Member
#2
Ok so onto the performance.

Discovery vs QAV500 - No contest, the Discovery with the special 1000kv motors is as solid as a miniquad.
The QAV had 13x4.5inch CF props the Discovery has 9x5 Plastic props but of much higher quality.
The QAV felt like driving an old mercedes, comfortable and washy, like driving on a waterbed, the Disco is ROCK solid.

This was with the Naza which I had lying around from a downed Phantom, I haven't test flown with the Pixhack yet but will be trying it out tonight however I must say I have never experienced something so locked in besides a mini-quad.

I think this thing would be rather fast as well. Testing to follow.
 

Snarls

Gravity Tester
Mentor
#4
YESSSS nilsen always coming through to satisfy my hunger for sweet builds and this time he has my favorite recipe. Do you notice an advantage with KISS ESCs on a larger build? I thought those were mainly for miniquads and acro flying characteristics. Also can you tell me what your AUW is and what battery is best for max flight time.

Planning a Disco build myself and am concerned how stable and efficient it will be, so it is good to hear you find it rock solid. My most recent AP quad is so floaty and drifty that I don't feel confident flying it. I'm planning on the normal Disco instead of the pro and I will construct the gimbal system myself. I actually want to eventually get a 3-axis gimbal on it like the guy here. He also has a really cool mod with folding arms that I want to do as well.

I will surely keep an eye on this thread.
 

nilsen

Senior Member
#6
sounds like you found a nice AP plat form.

any pictures handy?

chris.
As requested:

Front with gimbal and Gopro
NMR_2889.jpg

The motors are a custom wound job designed by TBS and made by Tiger
NMR_2890.jpg

Top view, I think she's very sexy.
NMR_2891.jpg

The "Guts"
NMR_2892.jpg

The discovery has a current measurement built in however I also wanted to voltage/current measurement for the pixhack so I added the power module as well.
NMR_2893.jpg

The rubber bobbins which should help mitigate any jello
NMR_2894.jpg

Little handy Vtx holder - it's metal so it also acts as a heatsink.
NMR_2895.jpg

Crossfire - yeasssss
NMR_2896.jpg

The corssfire plugs into the pins at the back and then they pop out here in the man section of the board.
NMR_2897.jpg

Motor and arm
NMR_2898.jpg

More Crossfire.
NMR_2899.jpg
 

nilsen

Senior Member
#7
YESSSS nilsen always coming through to satisfy my hunger for sweet builds and this time he has my favorite recipe. Do you notice an advantage with KISS ESCs on a larger build? I thought those were mainly for miniquads and acro flying characteristics. Also can you tell me what your AUW is and what battery is best for max flight time.

Planning a Disco build myself and am concerned how stable and efficient it will be, so it is good to hear you find it rock solid. My most recent AP quad is so floaty and drifty that I don't feel confident flying it. I'm planning on the normal Disco instead of the pro and I will construct the gimbal system myself. I actually want to eventually get a 3-axis gimbal on it like the guy here. He also has a really cool mod with folding arms that I want to do as well.

I will surely keep an eye on this thread.
Yes indeed! I enjoy building as much as flying, glad I could tweak your interest!

The Kiss ESC's are an absolute dream, they run very cool and are whisper quiet, the motors just pur along, I must say, if anything, that makes them worth the money.
I originally purchased them for a miniquad but they are a little too big when compared to the 18amp etc so I didn't end up using them, now I had the perfect opportunity.

The AUW is: 1800g (3.97lb) with a 5000mAh Zippy compact and gopro.

I will take it out shortly to give it a proper test flight and a tune.

I have a 5200 mAh battery which fits nicely in the back, the Zippy compact barely fits, incredibly snug.

What else I like is the TBS core built right in to see mAh used as well as flight time and voltage, simple OSD, it's all you need.

I will be strapping this to a backpack for Skiing etc.

Maiden:

 

Snarls

Gravity Tester
Mentor
#8
A very good looking build indeed. Looks like she is flying well, and the gimbal looks very smooth. I'm surprised the AUW is only 1800g. I'm shooting for 1700g, but I won't have all the goodies you have so I'm hoping for much less. I'm also thinking of using a 5200mAh 4s, but I'm wondering if getting two 4000mAh 4s is a better choice.
 

nilsen

Senior Member
#9
A very good looking build indeed. Looks like she is flying well, and the gimbal looks very smooth. I'm surprised the AUW is only 1800g. I'm shooting for 1700g, but I won't have all the goodies you have so I'm hoping for much less. I'm also thinking of using a 5200mAh 4s, but I'm wondering if getting two 4000mAh 4s is a better choice.
Thanks Snarls,

I just came back from flying 3 packs, one Zippy compact 5000mAh, one "desire power" 5200mAh and one "desire power" 6200 mAh which I had to strap underneath.

1. Zippy compact - my opinion is stay away from these batteries, in the TBS core it said I had used 2000 mAh and but the voltage was already dipping below 14 however I still managed well over 10 minutes on this pack as I did the autotune which takes about 12 minutes.

The 5200mAh "desire power" got me 15 minutes and firs perfectly into the Discovery, it's a long, slender battery though.

The 6200 strapped underneath was good as well althoght as you can imagine it didn't allow the quad to sit on the ground normally.

I would say if you can get a 5200 4s which will fit then go for that, you will get a good 15 minutes, or more if you are creating a lighter craft.

What would you not add to save the 100g?
 

Snarls

Gravity Tester
Mentor
#10
What would you not add to save the 100g?
Well I plan on getting the regular discovery plates which have less on them and should be a little lighter. I will also be using a smaller receiver. I'll probably be using a Pixfalcon instead of a regular Pixhawk because it is lighter and cheaper. Lastly my gimbal for now is plastic and not metal. With all that said, adding a third axis to the gimbal may take another 100 grams.
 

nilsen

Senior Member
#11
So I have been flying twice with it.

On the Zippy compact 5000mAh the core told me that it had 1500 mAh consumed but the voltage was already dropping to 13.9V but it was about 14 minutes flighttime.

On the "Desire power" 5200 mAh I got nearly 16 minutes of mixed flight-time which is more than the QAV500.

On the "Desire power" 6200mAh which I had to strap underneath I flew for 10 minutes but I feel it was too heavy.

I had to drop the gains quite a bit as with the smaller props and 1000kv motors this thing flies like on rails, I love it.
 

nilsen

Senior Member
#14
Hang on... His folding mechanism is just removing 5 of the screws?

I am very curious how he attached those tarot CF tube holders to the frame. Did he use the holes already on the frame or did he drill new ones?

Nightram over at the FPVLab forums has a similar concept as well.
http://fpvlab.com/forums/showthread.php?43539-Concepts-for-the-TBS-Discovery-Pro-(all-forms)
I looked at the link as well, so the solution is simply to undo the screws and then re-insert them before fly-time...

Does anybody else have any experience with this?
 

nilsen

Senior Member
#16
I'm not sure whether that technique will wear out the screw threads over time though.
How are you strapping the battery to the bottom?
I actually just use the same strap which I use when Iput the battery in the rear comparment.

Next time I will use the second strap as well though as hanging on by a single strap was a bit dodgy.
 

nilsen

Senior Member
#17
Experts, hello.

I have been flying the discovery with the Pixhack and it is rock solid when in hover and when in ascent/descent after running an autotune however when I fly forward quickly or bank sharply there are a lot of shakes.

Is this due to the nature of Multirotors as they tilt forward or because the PID's for pitch are presumably too high.

For APM, would you add some D and remove some P?

Thanks!
 

Snarls

Gravity Tester
Mentor
#18
If the shakes are constant during fast flight then decrease P until they go away. If there is some oscillation/bounce after a quick movement, but that disappears after, then increase D. Not sure if the pixhawk has TPA, but you could also increase that so that the PIDs decrease a little as your throttle gets higher.
 

nilsen

Senior Member
#19
Thanks Snarls,

I have decreased i and P a little on the pitch axis as it was very very high after the autotune.

APM doesn't have any TPA unfortunately but I Took it out for a flight and it's much, much better. I think I can decreas a little more but it is pretty damn solid now.

Cheers!
 

jhitesma

Some guy in the desert
Mentor
#20
Seems like a lot of autotune routines tend to err on the side of too high on P's I don't fully understand why but it seems somewhat common across most autotune's I've seen.

You may want to try adding a bit extra D to help as well, I've found a lot of times that when I lower I and P it takes a bit of extra D to get things nice and stable. But that could just be my luck ;)