Let’s design a multirotor together.

[SandervG 1,521]

..I like where you are going!

 

[woofy 12]

I decided to have a go at building the waterproof quad I illustrated earlier.

These are the parts I ordered for it:

Hobby King 2.4Ghz 6Ch Tx & Rx V2 (Mode 2)

Thunder QQ Super - Multi-Rotor Flight Controller

Multistar 2212 - 920KV Multi-Rotor Motor Set w/CW and CCW Threaded Shafts (4pcs/box)

MultiStar 10-4.5 (CW Rotation) Multi-Rotor Prop slot (DJI) Style Hub (pack of two)

MultiStar 10-4.5 (CCW Rotation) Multi-Rotor Prop slot (DJI) Style Hub (Pack of Two)

Afro Slim 20Amp Multi-rotor Motor Speed Controller (SimonK Firmware)

Turnigy nano-tech 1300mAh 3S 45~90C Lipo Pack

This turned out to be a bit of a poor choice. Firstly the motors are fitted with 3.5mm bullet connectors and the ESC's has 2mm bullets. Next the ESC's did not have a built in UBEC so I had to order:

2mm Gold Connectors 10 pairs (20pc)

Turnigy 5A (8-40v) SBEC for Lipo

 

 

Finally built I was ready for my maiden flight, this lasted for about 6 seconds. I gently lifted of about 0.5 meter and the quad began to drift towards a brick wall. I mover the rudder to correct and guess what?

The rudder on the Tx is reversed and I accelerated into the wall - crash. I released the throttle and it fell to the concrete - crash. Poor thing has two broken legs. I now have a programming lead on order for the Tx.

After a repair I was ready to try again. The next flight was much longer - around 10 seconds. I had decided to take it onto the back lawn. It took off and again started drifting but this time I was ready and corrected it. However it then started to drift down again so I gave it a bit more throttle. My finger slipped and it powered upwards - and I mean really powered upwards. Phenomenal acceleration. It hit a high branch of an apple tree and flipped over. I released the throttle in a panic and - crash. This time with much more damage, broken legs, arm and back. Also damaged a prop. It's now grounded until I can get more props.

I'm down, but not out

 

[mrwong 5]

Wow Woofy Nice design! What is the weight of that thing loaded? 1300 mah 3s seems a little small for a copter with 10 inch props.

 

[woofy 12]

Take off weight is 0.8 kg. I have no idea what the flight time will be with 1300mah. There might be space for two batteries with a few changes but its quite cosy in there. I will continue using it as a practice machine.

I have a better https://www.hobbyking.com/hobbyking/store/__56052__HKPilot_Mega_2_7_Flight_Controller_USB_GYRO_ACC_MAG_BARO.html on order. I think I will eventually need a better radio as there are not enough switch options on the one I have for mode selection on the new controller.

 

[mrwong 5]

I can see your diving right in! Im using a turnigy 9x receiver and transmitter for my acro quads and such (9 channels). On my long range phantom 2 v+ i use a turnigy 9x controller with a UHF Dragonlink for maximum range and control stability.

What i would recommend, is that you get a low battery buzzer from hobbyking as well. This will give you an indication when your pulling to much amps from the battery drawing it down past its safe zone. You dont want that lipo catching fire inside there!

 

[woofy 12]

I agree, I have a voltage/current monitor for the APM and telemetry link on order as well.

(Also have a https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=62530 too, but it's not getting fitted until I stop crashing).

Do you use a mode 1 or mode 2 transmitter for your quads?

 

[mrwong 5]

I use a mode 2 for my quads Throttle and Rudder just feels right on my left stick. Seems to be the common default for most games and comes natural to me like that. Fly in the configuration that feels natural to you.

That camera is a GoPro look a like! So Cheap and seems to have some good specs too!

 

[coen 11]

I decided to have a go at building the waterproof quad I illustrated earlier.

[...]

Wow man, great to see you moving so fast! Too bad about the crashes... did you manage to test the waterproofness of the frame? How did printing go?

For me I've got little time to spend on this project at the moment: new job, new house...

 

[woofy 12]

Just uploaded a video of my MK1 waterproof quad flying - and crashing.

 

 

[SandervG 1,521]

Hi Woofy,

you are speeding ahead! The crash was luckily/..unfortunately ( :wink: ) not as spectacular as the title made it sound.

Of course by all means you should do whatever you want to do, but I was hoping we could do this as a group project

and we could all benefit from the amazing wide range of skill sets we have in this community

 

[gr5 2,172]

I'm speeding ahead also. I already designed the critical 3d printed parts (still want to create prop guards and some kind of ninjaflex mount for camera) to get into the air.

I care more about folding arms than water proof. And photography is by far the most important thing. That's the main reason for the asymmetry. Anyway I'm still waiting for a few more parts (RC wires, bullet connectors). I will publish my design when it's a little more "done" than it is now. It's a 500 meaning the diagonal motors are 500mm apart.

 

[gr5 2,172]

By the way I updated my parts list slightly as I managed to save some money and my total parts list is down to $395 post #132 in this forum - here's a direct link:

http://umforum.ultimaker.com/index.php?/topic/6657-let’s-design-a-multirotor-together/?p=69049

I will keep this topic informed. Contact me directly if you want any details and I'll probably publish the answers here. Everything is in flux plus the actual ordered parts were often on ebay and shipped from USA so the actual shopping links may not be relevant to you but they are easy to find once you know what the part is called e.g. "m3 8mm screws".

The 3d printed frame by the way is about 250 grams which is about half to 1/3 the weight of the typical "500" quadcopter frame. And weaker but I can always just print up anything that breaks. My total weight is 1100 grams at this point including camera and gimbals and everything. The heaviest things are the frame (260g) the motors+props (250g) gopro+mount+gimbals (195g) and 2.2Ah 3S battery (105g).

 

[Labern 774]

Hi Woofy,

 

you are speeding ahead! The crash was luckily/..unfortunately ( :wink: ) not as spectacular as the title made it sound.

 

Of course by all means you should do whatever you want to do, but I was hoping we could do this as a group project

and we could all benefit from the amazing wide range of skill sets we have in this community

 

I would also like to contribute to a group project as my main expertise is engineering and not with electronic equipment.

It Is kind of good having a few people build some, so they can tell us what works and what doesn't.

I think if you want a group project then at some point someone will have to decide what will be the requirements.

[Titus 170]

Anyone with even greater ambitions? What could our Ulti-Drone do?

 

 

[woofy 12]

My 1st quad has now been retired after have one crash too many :sad:

but the 2nd version is ready to go

I learnt allot from the 1st one, especially not to by cheap rubbish. The flight controller did not have the sophistication I needed so that had to go and I'm now using this one. The body was not large enough to hold a decent sized battery and all the new electronics so that is now much bigger - about as big as I can print on my UM2.

below is a cut-away showing the battery mount and above that the printed sprung mount for the flight controller. The original flight controller was stuck down with a double sided pad that did not want to come away again - yech! So this one has a proper printed clamp.

The GPS module (with the compass) is mounted high in the dome away from high current motor wires.

Here is the printed and assembled quad. I have so far only done a stamina test, by making it hang stationary in the air exactly the way bricks don't. It reached over 18 minutes before going into RTL mode and landing safely

So what's everyone else up to?

 

[jonnybischof 60]

Very nice work!

I'm too busy with other stuff :(

Making a better printer is taking up more of my time than expected...

 

[gr5 2,172]

My copter has been taking a ton of my time. A few times I almost gave up and ordered a frame but I'm still using my own frame for now.

I had many crashes or not-so-gentle landings and all my props have nicks and such and so I ordered some new props and am waiting on them. I've had many successful flights but the thing is just too unstable. I have the same apm controller by the way. It's very cool but calibrating PID is a pain!

I learned a few important lessons. One is probably to tie it to a strong horizontal wire/string and calibrate PID thoroughly before the first flight in both roll and pitch.

Another lesson is that the battery can't just be loosely attached - if the battery swings at all it confuses the PID controller and makes for extremely unstable copter that is flying fine one minute and suddenly upside down with no warning.

I learned on the APM how to turn on "IMU" logging (in addition to default logging) and it's important to "fly" while holding the copter indoors for a few seconds and then look at the acceleration noise for x,y,z and keep it under .3g or even better under .1g.

Balancing props doesn't help if one of the blades is subtly bent such that one blade has more lift than the other. This can actually be violent enough to twist the arm hard enough to snap it off to say nothing of x,y,z acceleration noise.

I got my go pro camera gimbal mount working nicely.

I think your vibration reduction might be too severe. You want the low/medium frequency acceleration to make it cleanly to your apm. The high frequency stuff is the only thing you want to dampen. I'm not sure that those PLA twisty/springy mounts will work. But please let me know if they do!!

 

[drayson 75]

Guys, your lucky... your quads grow and fly, but mine... don´t ask...

The Fatshark stuff has arrived and works great, my printed frame is ready, the electronics mounted - but when switching on and starting, it rolls immediately to it´s back... (pls. no comments related to girlfriends... :-) )

Seems I have some issues in the sensor config...

So I guess, there´s a long way to my 3D printed flying scorpion... :-(

 

[woofy 12]

@gr5

What is the take off weight of your quad? From the motors you listed a few posts ago it looks as if you have over 3.5kg of thrust available. From what I've read, a quads thrust should be double its weight so a 1.5kg quad would be about correct. If its much lighter than that it could give stability problems for being over powered.

Do you have a photo in ready to fly condition?

My 1st quad had a similar sprung flight controller mount. I've had quite a few iterations of this and I think its firm and stable enough now. I'll try to get a flight video together over the weekend - weather permitting. By the way, there's no PLA in it. It's 100% ABS and mostly weld bonded with acetone. Only the dome and legs are screwed on.

@drayson

I've had this too and wrecked a few props on this. Some things I'd check:

Make sure your flight controller is set to the correct configuration, quads can be + X or H shaped, it matters to the controller. Make sure the motors rotate in the correct direction, Make sure the controller is facing the correct direction and the ESC's are plugged in to the correct position on the controller. You should also ensure your ESC's are calibrated otherwise some will start before others and the quad can flip before the controller PID's can compensate.

Please show us a photo and maybe a parts list for your quad.

Who else is working on a multicopter - any hexcopters in the works?

 

[drayson 75]

Thanky for the hints woofy!

I printed the nice V-tail quad you can find on thingiverse via "sorpion" (I know, it should be named scorpion, but it is written this way there...) in scale 1:2.

I will use your list as a checklist - hopefully I´ll find the problem...

 

[gr5 2,172]

drayson I recommend holding the quad in your hand very level minding the rotors and then with your "weak" hand give it some lift then push the control sticks in the directions to make it tilt and such and see if it "tries" to go the correct direction.

Also yes double check that you plugged the correct motors into the correct spots.  If you reverse some of the wiring then the controller corrects in the wrong direction and flips right over.

More likely though there is some kind of loose thing or instability.

I'll post weight and photo in a minute.

Edited July 14, 2015 by Guest

[gr5 2,172]

1322 grams. It has incredible power. I'd say I've done a 2g climb and it's amazing to watch - it just shoots up like a rocket. Like dropping a rock - but up instead of down.

Okay so here it is as it is today. I have *not* flown it with the camera attached. I'm quite worried about stability and may need to redesign that - the battery is way the hell back there which is needed for center of gravity with the camera way out front like that. Before I try flying it again I will be removing 2 inches off the back of the aluminum bar stock on the back and about 1/2 inch on the front so it won't hit 10 inch blades (I have some brand new 10 inch blades which I might test out if I don't get my new 9 inch sooner).

Note the 4 arms have 2 different designs. I'm printing the second red one now and a new white one later today. Replacing only those 2 arms reduced the vibrations significantly. The new design has a "eifel tower" grid look and they are much more stable for twisting motions when you have crappy prop blades.

The APM is currently on 2 inches of foam which is *worse* than one inch of foam because the green velcro is so tight. I ordered some vibration isolators (they cost almost nothing) and plan to print something up when they arrive to mount the apm better.

I really want to redesign so many aspects of this copter! The top plate redesign is next so that I can attach everything more simply, elegantly, and symmetrically. And without so much velcro. And without so many drilled holes and dremelled slots, lol. When I designed the top plate I didn't have any parts and I didn't know where anything was going to go and just put in some randomly placed slots for velcro.

 

[gr5 2,172]

Those motors can put out 880g each with 200 watts but my battery can only put out 528 watts maximum. Divide that by 4 and you get 132W per motor if all working equally hard. That "2G climb" was without the camera and aluminum bar stock and gimbals or 235g less (I have weights and position of all items in a spreadsheet for easy access) or 1087 grams when I was flying it (again, have not flown it yet with 1322g weight).

So perhaps the motors when all working can only put out 2323 grams of lift versus 1087 g weight. yeah - that's still over 2 gravities. :eek: :-P

Even worse, if the apm decides to roll the copter, the battery isn't working to capacity and can give those motors full 200W power. So maybe "yes it's over powered". I don't know. But adjusting PID values should help. I already lowered the P values and that helped a lot. I have notes somewhere about the original and current PID values. I will be tuning that some more when I get my new props.

 

[woofy 12]

1322g is heavier than I'd expected but I can see it now with the photo. Mine is 1.4kg and I've yet to fit the camera and gimble.

The apm has a pid autotune feature. If you can get it to hover in Alt. hold mode, maybe you can use that to do the fine tuning.

If you are using the compass in the GPS module and if it's the same as mine (the hobbyking kit) then you might want to check the direction, it looks to be around 45 degrees CW from where it should be for north to be the forward direction.

I like where you have the gimble, and that you have made your own. I have this controller winging their way from hongkong at the moment.

Here's a peek at the inside showing my sprung apm mount and gps orientation.

 

[gr5 2,172]

There's no arrow on mine to indicate "north" although I think there might be an LED. I'll bring it outside and check to see if it agrees with where North truly is. Does yours point to true north or magnetic north when you are running the apm planner 2 software connected to the apm unit with a USB cable?

I ask because for me they are 13 degrees apart. Plus I haven't hooked it up to a laptop while outdoors.

I've been able to hover but I'm not sure what happened to the auto calibrate thing. I think it was too windy when I tried that. I guess I'll try that again just to see what PID values it comes up with.