First build - maybe bitten off a little too much!

[jtbutcher]

Hi!

Relative newbie and lurker here, with a little experience building a couple of foam flyers, and some experience flying (controlled crashing) a hubsan h107c round, I decided to build something a little more ambitious.

https://rotorbuilds.com/build/12935

I think its finally ready to fly, the only issue I may have is that a clockwise yaw on the floor with no props seems to make it want to vibrate and dance around the floor, I think this is just calibration been out and the flight controller not been happy about the local em environment, but I'm surrounded by computers and power lines at the office so calibration never seems quite right.

Please can anyone offer any advice on the build (or point out some fundamental flaws!) before I commit to a maiden flight and risk the ire (or mocking) of south Brum dog walkers?

[Cheredanine]

Hi,
So I build a lot of quads but mostly in the 5 inch class, nothing that size.

What you are describing though (worrying behaviour when testing with props off involving shakes, oscillations etc) it typical and in and of its self is nothing to worrry about.

The yaw axis is the most problematic for quads.

When you command the quad to do anything with the props off it tries to do it, however without props, it’s efforts have no effect directly on what it is trying to do, so the P and I terms make it try harder and harder.

This causes motors to spin faster, which, without props, causes oscillations, some of which are sudden movement in the direction the quad is trying to move, then the d term kicks in and p and I drop, only to bounce back as the oscillation changes direction, causing motors to spin up and slow down rapidly, making the oscillations worse and quite typically making the quad dance across the ground

In short then what you are describing is normal, it does not describe a problem (it doesn’t mean you don’t have one but it isn’t indicating one)

Ps you are by no means the first person to encounter this when they start to build

[ched]

I couldn't work out what components (Flight Controller, esc etc) you are using so this is just a quick check list.

Have you calibrated esc? If not calibrate them.
Have you calibrated the gyros? If not calibrate them to a level surface.
When you have the quad connected to a computer and move it around does the 'model' quad image move the same way? If not the FC might not be in the correct orientation (can correct either in software or by rotating within the frame).
Have you taken it outside and checked it gets enough satellites? If you have no way of verifying this in the field DO NOT rely on gps to get you home!!! It may not have locked on to enough sats and may think it's home is in China!!!!

Have you set failsafes? i.e. if you switch your tx off does quad cut power? This gives you a safety if quad tries to fly off! With props OFF arm qud and give it a little throttle, then switch tx off. Does it shut down the motors? If not set failsafe.

Might be worth adding a few more cable ties to attach wires to frame a bit more.

Sorry for all the warnings but you have 4 10inch sharp props spinning fast and you want to make sure you are as safe as possible.

Good to see people building 450/500 size quads, they are great for aerial photography and learning. As it's bigger it is much more docile than a 250 size quad so great for learning with.

Have fun and stay safe and legal.

[jtbutcher]

Hi,
So I build a lot of quads but mostly in the 5 inch class, nothing that size.

What you are describing though (worrying behaviour when testing with props off involving shakes, oscillations etc) it typical and in and of its self is nothing to worrry about.

The yaw axis is the most problematic for quads.

When you command the quad to do anything with the props off it tries to do it, however without props, it’s efforts have no effect directly on what it is trying to do, so the P and I terms make it try harder and harder.

This causes motors to spin faster, which, without props, causes oscillations, some of which are sudden movement in the direction the quad is trying to move, then the d term kicks in and p and I drop, only to bounce back as the oscillation changes direction, causing motors to spin up and slow down rapidly, making the oscillations worse and quite typically making the quad dance across the ground

In short then what you are describing is normal, it does not describe a problem (it doesn’t mean you don’t have one but it isn’t indicating one)

Ps you are by no means the first person to encounter this when they start to build

Thank you! I had kind of picked this up googling round and reading about PID, but its one of those niggling things I had to check on before kicking the baby out of the nest 

[jtbutcher]

I couldn't work out what components (Fliht Controller, esc etc) you are using so this is just a quick check list.

I should have put a full parts list in here rather than linking to that other place 

Components are:

• S500 Frame
• Mini CC3D Revolution Flight Controller (F4 Based) running Librepilot 16.09
• Oplink Mini Air Ground Telemetry (433Mhz)
• UBLOX Micro M8N GPS and Compass (Compass connected by I2C to the Revo)
• Turnigy Multistar 4-in-1 30A ESC (Supports dshot125)
• 2 sets of Multistar Elite MT2312 980kv Motors with DJI style 9443 self tightening props (I have some 10" carbon fiber props as well once its air worthy and tested)
• Turnigy Multistar SBEC 5/10A 5v/12v output
• Turnigy iA6c Receiver (with battery detect connected to the battery source for battery monitoring) with a Turnigy TGY-i6 (with 10ch firmware update)
• Cheap crappy Pano360 (270 degree) camera hanging of a cheapo rail mount from amazon (to be replaced by something more appropriate when filming the fast approaching ground is less likley  )
• Turnigy 5000Mah & Zippy 8000Mah 20/30C Lipos

Have you calibrated esc? If not calibrate them.

ESC's are calibrated (I think, certainly the esc made the calibrating noise)

Have you calibrated the gyros? If not calibrate them to a level surface.
When you have the quad connected to a computer and move it around does the 'model' quad image move the same way? If not the FC might not be in the correct orientation (can correct either in software or by rotating within the frame).

Gyros have been calibrated, but I think I need to redo along with the board level on the ground instead of a first floor office where the floor level is questionable.

Have you taken it outside and checked it gets enough satellites? If you have no way of verifying this in the field DO NOT rely on gps to get you home!!! It may not have locked on to enough sats and may think it's home is in China!!!!

GPS has been able to establish lock, but I think initially I plan to test fly on gyro/compass only, I do need to get the compass properly calibrated, pig to do without help on this biggish frame (and needs to be done away from the power lines 300ft away.)

Have you set failsafes? i.e. if you switch your tx off does quad cut power? This gives you a safety if quad tries to fly off! With props OFF arm qud and give it a little throttle, then switch tx off. Does it shut down the motors? If not set failsafe.

Failsafe is set to dead throttle. I even went so far as setting dual switch arming to try and minimise the chance of finger choppage!

Might be worth adding a few more cable ties to attach wires to frame a bit more.

I have an open pack ready, it will look like a flying cable tie by the time I am done ::)

Sorry for all the warnings but you have 4 10inch sharp props spinning fast and you want to make sure you are as safe as possible.

Thank you, this was why I posted, I really don't want to hurt myself and definitely not anyone else through some silly mistake.

Good to see people building 450/500 size quads, they are great for aerial photography and learning. As it's bigger it is much more docile than a 250 size quad so great for learning with.

Have fun and stay safe and legal.

Once I am happy I want a more capable camera on there and maybe take things further, for now I just want to get to grips with it and have some (safe and legal) fun 

[atomiclama]

I know you have it all built up but I'd strip it down to the bare minimum and put some cheap sh$it props on it for the initial flights.

First time you power it up and the props are on wrong or the motor order is out, I wouldn't want you to flip that quad and smash all the components sticking out on top.

[jtbutcher]

I know you have it all built up but I'd strip it down to the bare minimum and put some cheap sh$it props on it for the initial flights.

First time you power it up and the props are on wrong or the motor order is out, I wouldn't want you to flip that quad and smash all the components sticking out on top.

No worries, the dji style 9443 are cheapos from amazon, my less cheapo (but still pretty cheap) carbon fiber props are not going anywhere near to start. The thread on the sets of motors is cw/ccw so I went as far as drawing little arrows on the motors to get the spin direction right  ::)

So.... the two CW motors go at the front and the two CCW at the back..... that's how it works isn't it?? 

[atomiclama]

So.... the two CW motors go at the front and the two CCW at the back..... that's how it works isn't it?? 

That's what I'm doing wrong 

[ched]

I started my learning with my F450 after a failed attempt to learn with a zmr250  ::)

I started without any 'landing gear' on the bottom just the little feet under the motors. That gave me a feel for it and less weight to crash. Less weight is always better in a crash as less inertia  ::)

I would make sure you have a way to differentiate between sides. Reason being that when its about 50m away it's difficult to work out which way it's facing!!! I put white led strip on front, red at rear gReen on right and Blue on left. That way I could see the orientation much easier. I just bought 0.5m of each rated at 12v from ebay.

How many cells are in the lipos? Mine runs 3S on 10inch props and 4S on 8inch props.

On mine with PROPS OFF I gave it a little throttle indoors while I held it then tilted it forwards to ensure forward motors spun faster to try and level it. Then same test either side and rear just to check it should perform as expected.

Good that you have done all the checks etc. Sometimes you don't know how much reading people have done and if they know what they should be doing. Seems like you are going in the right direction.

Maybe for first flight leave off landing gear as sometimes it's not that strong 

[hoverfly]

Just in case you forget. ::)

[jtbutcher]

almost scuppered before I've had time to take it out! decided to get the antenna sleeves on the antenna mount (https://hobbyking.com/en_us/hobbykingtm-adjustable-receiver-antenna-mount-dual-45deg-2-pack.html) and in stripping the clear plastic covering the exposed core, managed to break one not sure if it was the receiver or telemetry wire, but google says strip back the silicone and outer core to the same length as before and pray to the gods of UHF that its enough!

[hoverfly]

Panic ye not, it can be repaired. It is a fiddley job but with care it will be as good as new, just take your time and cut accurately.   

https://oscarliang.com/repair-2-4ghz-antenna-rx/

[ched]

Just remember that the control rx (the iA6c ) the frequency and length will be different to your Oplink Mini Air Ground Telemetry (433Mhz). So don't get the wrong length on the rx/tx as the range will be effected.

I have not had to change the antenna length just coil up the spare length. The stripped back bit doesn't need to be exposed wire just strip back the outer conductor.

[jtbutcher]

Unfortunately I am still trying to find a quiet time to maiden it, why does everyone want to go to the park when the suns out?! 

[Shawn]

I have just built a big camera bird and I had trouble with it being very unstable.
Was my ESC calibration. I sorted mine by having my transmitter on and linked whilst doing it.
First flight was on our double bed in the bedroom.
Wait listen ::) I held it in my hand above the bed and armed it and flew it whilst holding it. I was able to fly it and see if it was OK without letting go. Not recommending this but I have really strong upper body strength from being a wheelchair user and it wasn't going anywhere with me holding it. It was erratic and would have instantly crashed outside. One motor wanted to bend the arm it was on and one did not spin at all.
That's when I discovered the bad ESC calibration.

That remedied the next bed test I felt like I could have let go of it and it would have hovered.
Next test I tied the drone to my spare wheel in the country with a 3m long nylon 200lb break strain line.
Took off and it was perfect. Could control it and it hovered well. Untied it and took it for a spin. No problems!
I tend to do things my own way :evil :evil

[jtbutcher]

I have just built a big camera bird and I had trouble with it being very unstable.
Was my ESC calibration. I sorted mine by having my transmitter on and linked whilst doing it.
First flight was on our double bed in the bedroom.
Wait listen ::) I held it in my hand above the bed and armed it and flew it whilst holding it. I was able to fly it and see if it was OK without letting go. Not recommending this but I have really strong upper body strength from being a wheelchair user and it wasn't going anywhere with me holding it. It was erratic and would have instantly crashed outside. One motor wanted to bend the arm it was on and one did not spin at all.
That's when I discovered the bad ESC calibration.

That remedied the next bed test I felt like I could have let go of it and it would have hovered.
Next test I tied the drone to my spare wheel in the country with a 3m long nylon 200lb break strain line.
Took off and it was perfect. Could control it and it hovered well. Untied it and took it for a spin. No problems!
I tend to do things my own way :evil :evil

Pegging it down with some string has crossed my mind, but I'm struggling to get away from the missus of an evening to go and test at all!