tricopter maximum flight time

[treecopter]

Hi!
I'm new to this hobby and i have just finished my tricopter. the tricopter is made of aluminium booms and plywood frame plates, i'ts equipped with apm 2.6 with gps, ntm propdrive 26-28 1000kv with 1045 props, afro slim 20A esc's, 3s 2200 lipo and a tower pro MG90 servo for the tail.

I'm not happy with the way it flies. The flight time is only about six minutes, it oscillates in the yaw axis and lowering the p-gain dont seem to work.

I'm planning on rebuilding it in carbon fiber and do the wiring smarter to make it as light as possible. also I think my motors are bad. It sounds like the ball bearings have got sand in them, they go clacklacklack...

so... I'm wondering what motors and props i should buy for maximum flight time.I also wonder if you guys have some tips and/or tricks to make things as light as possible.

Thanks in advance!
/treecopter

 

[Montiey]

I would google what other people use as settings for their tricopters. That way you would know if you are forgetting something, or if your gains are way off.

I don't know much about copters, but I have a shipment of stuff on the way for my RCExplorer scratch build tricopter. Hopefully it will work good enough to keep.

good luck! Don't get discouraged.

 

[C0d3M0nk3y]

I'm not happy with the way it flies. The flight time is only about six minutes

What's your all up weight?

it oscillates in the yaw axis and lowering the p-gain dont seem to work.

Is it a slow or fast oscillation? What are you using for a tilt mechanism?

 

[treecopter]

@ C0D3M0NK3Y
It is a slow oscillation and my tilt mechanism is very similar to hallstudio's tilt that he use for his tricopters, exept the servo is under the boom.
I don't know the total weight because the kitchen scale is broken. All i knownis that it is quite a bit heavier than my brothers dji phantom .

 

[joshuabardwell]

For long flight time, first remove weight.

When you say six minutes, is that active flying or just hovering? My quad has a similar setup (980 kv motors, 10x4.5" props, 2200 3S battery) and I get about 6 minutes of active flying, or maybe 8-9 minutes of just hovering. My AUW is about 1 kg.

To get longer flight times, here are some options:

1. Larger battery. There are diminishing returns here, as the increased capacity is wasted on the increased weight, but depending on how close your current AUW is to the edge, you may be able to get more flight time with more battery. Test this out by building/buying a parallel adapter and running 2x your current battery and see how your flight time changes.

2. Go from 3S to 4S. May require different motors/props, but in general, you can squeeze more flight-time-per-gram out of a 4S power system than 3S. Your motors are already rated for 4S, and your ESC's can take the max those motors can, so there is little reason not to go for it. Use the biggest props you can while keeping the current draw below the rated amount. The product page for that motor says 9x6 is the max on 4S, but it also says 9x4.7 is the max on 3S, which you are currently exceeding, and presumably you haven't burned them out yet. Get an amp-meter and know for sure.

 

[treecopter]

@joshuabardwell
@C0D3M0NK3Y
I have som 8" props i will try tomorrow. The all up weight is 1000g.
The motors are 43 cm from the cg just so you know. I get six minutes of active flying. I want at least 10 minutes.

 

[joshuabardwell]

I have som 8" props i will try tomorrow. The all up weight is 1000g.

Smaller props will probably give lower flight time, all else being equal. With 1 kg AUW, you can probably afford to put another 2 Ah of battery on there at least. In gentle hover, I used to get something like 10 minutes off a 2200 mAh battery. With two of them, I got something like 18 minutes. Nowadays, I get less flight time because my batteries are getting older--which is something to keep in mind.

I would think if you used a 4000 mAh 3S you could get at least 10 minutes, and probably more like 15. If you go up to 4S with the 9x6 props, you will have a nominal 4 kg of thrust, for a TWR of close to 4:1. You will be flying at less than half throttle almost all the time. If it were me, as long as I was going to buy a new battery anyway, I would think about going to 4S with 9x6 props. But the cheapest/simplest thing to do in the short term is to get or build a parallel adapter and try 2x of your existing batteries.

 

[C0d3M0nk3y]

@ C0D3M0NK3Y
It is a slow oscillation and my tilt mechanism is very similar to hallstudio's tilt that he use for his tricopters, exept the servo is under the boom.
I don't know the total weight because the kitchen scale is broken. All i knownis that it is quite a bit heavier than my brothers dji phantom .

Have you tried lowering the yaw I gain? When your P gain is too high, it causes fast oscillation. High I gain causes slow oscillation (unless I'm getting the two confused).

Is there any slop in the servo or the tilt mechanism? I've had slow oscillations caused by a servo wearing out.

 

[C0d3M0nk3y]

@joshuabardwell
@C0D3M0NK3Y
I have som 8" props i will try tomorrow. The all up weight is 1000g.
The motors are 43 cm from the cg just so you know. I get six minutes of active flying. I want at least 10 minutes.

I would expect lower flight time out of 8" props, but it's worth trying. You might also pick up some 9" and try since someone pointed out in one of the previous posts that your motors are rated for those. Your 10" props might be putting too much load on them, causing them to lose efficiency.

I run 8" props on my tricopter with 1450 KV motors. When I keep the AUW under 800 g, I can get 8-10 minutes of flight on a 3S 2200 with no problems. When I add a clean plate and mobius camera and bring the AUW up to about 900 g, my flight times go down to 6-8 minutes.

 

[treecopter]

I tried my 8" props and it didn't even take off. My brother bought some 9x47 carbon fiber props but he didn't like the way his phantom flew so he will give them to me!
i will probably build a new frame in carbon fiber because my plywood frame plates got damaged in a crash with a tree, because of that my username is treecopter! x). My tilt mechanism dont have any slop and it runs with little friction I'll probably buy the sunnysky 2216 800 kv motors. they give me about 1.1 kg of thrust at 14-15 amps each! that will be plenty of power for my carbon fiber frame! they say that is on 11.1 v, is that a 3s lipo? in their diagram they have three different volt rows, 7.4, 10.0 and 11.1 volts. as far as i know 7.4 is 2s, 11.1 is 3s and 14.8 is 4s. so what kind of battery is that 10.0 volts?

 

[joshuabardwell]

11.1 is nominally 3S. I have wondered the same thing about 10 volts. I'm surprised you couldn't even take off with 8" props. There shouldn't be THAT much decrease in thrust. Are you sure you had them on facing the right way?

 

[Random_rc]

i use a website to tell me how long the battery should last. i have tested it by hovering my quad and timing it and it was pretty accurate. also the amount of throttle you use to keep it in the air will also change the result.
website : http://multicopter.forestblue.nl/lipo_need_calculator.html
matt

 

[HarleyRev]

Balance the motors and props , this might solve the clankity clank cclank sound.


Also check your weight/thrust ratio need to be 2:1 to fly , 2.2:1 to fly well . 2.4:1 for fast and agile.

If you dont have a scale , you should be able to determine a close estimate of weight by looking it up on the specs of all your parts.

I looked up your motor specs:Model: NTM Prop Drive Series 2826 1000kv
Kv: 1000rpm/v
Poles: 3
Motor Wind: 19T
Max current: 15A
Max Power: 176W @ 11.1V (3S) / 235W @ 15V (4S)
Shaft: 3mm
Weight: 54g
ESC: 20~30A

Prop Test Data:
9x4.7 - 11.1V / 113W / 10.2A / 0.632kg thrust
9x6 - 14.8V / 220W / 14.9A / 0.937kg thrust

On a 3s with a 9x4.7 prop your motors can lift 632 g , so around 1900g would be the total lift capability.
From what I see the 9x4.7 is the recommended prop size , the 10" may cause it to draw to high amps resulting in shorter flight time.

176 watts on a 3s , 6 minutes of flight is probably about right.

My quad weighs 1000g with a 2200mah 3s, motors are 130 watts and I get 10 minutes of flight out of that battery.

Since your motors are capable of 4s , you could try that , it will surely make it more powerful and should give you more run time because using a higher voltage on the motor would make it have a smaller amp draw.

you wanna run with the biggest battery your multi rotor can handle without taking away from its handling capabilities. The only way to do that is to find out the weight of your machine.

Using a 4s would give you 937g of lift with a 9x6 prop as per chart, for a total of 2811g of lift capability.

So with a 4s battery and 9x6 props, your max weight , with battery should be 1300g.

Hope this helps, best o' luck