Emlid

Community Forum

Aluminium Weaver


(Anton Pryamostanov) #1

From Spruce Goose to Aluminium Weaver.

The new build is slightly larger, much more rigid and supposed to be much more stronger.

The project features welded aluminium X frame built using ‘+’ profile.

2216 Sunnysky v3 motors 880kv, 1045 carbon propellers.

5500mAh 3s 45c LiPo

Dalrc Engine 40A ESC

And same Radiolink R9DS radio.

Maiden flight to happen this Saturday.
More details, pictures and videos will follow.

So far very happy with welded aluminium frame - excellent rigidity in all axis, light weight.

Cheers


(Christian Grüner) #2

Hmm, that looks heavy and prone to vertical vibrations :confused:
It will be quite prone to vertical vibrations on the arms, because of the profile of the Aluminum arm. A carbon square or round tube is much better suited for this purpose. Also means that less prop-wash will hit the arm, further reducing the source of vibration.


(Anton Pryamostanov) #3

Hi Wizprod,

What do you mean by Vertical Vibrations?
High frequency or just misplacement?

Misplacement shouldn’t be the case as ‘+’ profile is rigid enough.

Reg. weight - the frame itself is around 250g or less. It is 500mm. Not sure how much are same carbon frames.


(Anton Pryamostanov) #4

Here is the profile section.

Optimal section shape - for rigidity and reduced weight.
Total cost for frame - 3$ + welding rods spent around 15$ but this can be reduced.


(Anton Pryamostanov) #5

Well the build has around 3 kg of extra thrust.
That makes is barely controllable even in super easy flight mode.

Any advises how to improve this? Like decreasing servo high level from 1900 to 1700?


(Tobias Dahms) #6

Adjust the throttle response curve on your controller.


(Tobias Dahms) #7

Is there a power switch between the battery and the copter electronics???


(Anton Pryamostanov) #8

Yes, 3000W switch to easily disable motors/ESCs for safety, keeping Navio and Raspberry powered via power module.


(Anton Pryamostanov) #9

could you please share link how to do it in Mission Planner?

Thank you.


(Tobias Dahms) #10

Interesting approach, but I have never seen that before, I think it would be better to implement the motor interlock option in Arducopter and your RC.
One szenario I would fear is that the switch surfes corrode with the time and the resistance will rise until the switch melts away. Had that in my car once ;-(.


(Tobias Dahms) #11

I think that depends on your RC. What kind of RC are you using?

Did you run the auto tuning procedure?


(Anton Pryamostanov) #12

I use Navio 2 with Radiolink AT9S/R9DS.
I didn’t do the autotuning. Will do today - thank you.

Reg. the switch - i will consider soldering it then; rather than plugging. Currently it is plugged into soldered connectors and removable. Good point reg. corrosion. It is normal copper that can darken. Thank you.

Otherwise this is really useful thing except for large size of this switch. Helps to avoid plugging XT60 all the time.


(Tobias Dahms) #13

I also think that the switch could corrode inside. Actually I think it is highly unlikely that the motors will spinup without being armed. At the other hand you could accidentally arm the copter with the switch off, throttle up and then switch the switch :wink: I think that is extremely dangerous. I would not recommend to have the switch there.

And yes, I also don’t like plugging the connectors… .


(Anton Pryamostanov) #14

Valiable thought about corrosion inside.
Thank you.

Let’s see how this specific switch performs.
Otherwise next time will use sea-suitable boat switch.

Otherwise its very useful - very easy to restart or power off ESC.

Here are couple if more “inventions”:

LiPo with locking tape and radio with lead battery.


(Tobias Dahms) #15

I find the locking tape invention quite interesting, could you make a short video if the battery moves if you shake the copter wildly around?


(Anton Pryamostanov) #16

Done, Uploaded to youtube

It holds easily both drone weitght and/or battery weight. However I still recommend at least 1 battery strap for failsafe.


(Sebastian) #17

Do not get me wrong, but it is a really bad idea to use flat aluminium to build a quadcopter frame. Flat material has low resistance against bending and torsion. It will be resonant on multiple frequencies.
Aluminium has a very bad bending behaviour, with a very small elastic deformation region, before it is bend permanently and then brakes. The constant vibration from the motors/props and the downwash from the prop passing over the arms will weaken the material and change the behaviour of the quadcopter.

The power switch is another thing. It does not add security. A plugged/unplugged battery is a sure thing to determine if the copter is powered or not. The switch may fail in many ways and it is not as easy to see if the copter is powered or not.
Leaving the flightcontroller powered while the ESC/Motors are not, is also not good.
Some ESCs power up if they get power through the servo plug. So the ESCs go through their normal startup and are armed, while the motors do not get power.
Depending on what you do before you flick the power switch, the ESCs might be throttled up and you get a nasty surprise.


(Anton Pryamostanov) #18

I agree about flat aluminium. It is fully unsuitable.
That’s why I used non-flat profile section shape.
Sorry I only now took pic with proper angle on the profile section.

There is a tricky reversed construction on the upper profile to keep all motors on the same level.

The construction is rigid so far.
However I will do test it and will tell exactly.

I am not fully sure it is successful yet.
The main issue is deformation. The aluminium is soft, and it tends to deform even in rigid modules.

I will update.

Reg. switch - it’s mainly for convinience, not for security. But thanks for explaining about ESC surprise thing - this is fully valid risk.



(Tobias Dahms) #19

That is fantastic, I have seen the velcro before but only for attaching cabinets inside of cruise ships :wink: I will order some for my copter. Thank you!


(Tobias Dahms) #20

Why didn’t you use 10mm aluminum square tubes? If you can weld them together with two aluminum plates you could get a rigid and light platform. But 250g is already very light fur such a sturdy construction.