Short flight times, in the hope of increasing made it even worse. Please explain what to do!

ArduCopter
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1

Hello, I built a F450 quadcopter some time ago, basic thing: Old APM, some generic ESCs and crappy motors, FlySky receiver and a gensace 5000mah 50c 3s battery. After some configuring and messing around with some settings, especially PIDs I got it flying pretty well, added FPV, good range and LED lights that I almost never use.

But there was always one thing that was frustrating me is the flight time. Yes, I have done a post about this in the past in this forum, I’m sorry if you think I’m duplicating the question, but the conversation in that post went in the wrong direction that I hoped, people started telling bad advice to each other, etc…

So from there I made some progress on my copter. Here is what I upgraded:

  • Added gimbal

After that it just fell from the sky in the first flight, also have a topic posted about this, was underpowered, overheated motors. After that crash I replaced landing gear, thought it wasn’t enough, bought another very lightweight Tattu LiPo Battery that I thought is very good for the drone. It is the Gens Ace Tattu 2300 mah 25C 3s XT60 battery, I went to test it out and to my surprize it didn’t fall from the sky but rather very, very fast discharged the battery, in LESS than 4 MINUTES! Yes, the PID’s were off, I adjusted some more, it isn’t shaking as much at it was in the first flight, but still got 5 minutes only. It eats 25 amps in hovering…

I saw other people posting about this in this forum and most of the answers were: “Just live with the short flight times and buy more batteries”, or “reduce weight and that’s it”

Believe me, I tried to reduce the drone’s weight by changing the landing gear to VERY light Bamboo, the drone now weighs around 1.4 kg, IS IT STILL NOT ENOUGH??

Then I see some drones on the internet, like the DJI mavic air 2s or the Autel evo that can fly for 20 - 30 minutes, and yes, they weight twice as less, but have 10 times more flight time as mine!!!

Please give a normal answer and not like the examples I said above!

Thank you very much to anyone dedicating time on this question! Hope to see some improvements because I’m very frustrated and about it and about to throw it in the trash and buy a mavic mini and get flying normally.

If you need some additional info, logs, or something else, please tell me and I’m happy to provide anything you want!

P.S: Here is the most recent photo of my drone:
https://drive.google.com/file/d/1n0jfKgO5aRIguUL_hGwbPeqC7HQjDC-X/view?usp=sharing
https://drive.google.com/file/d/1aJKEJgGS-kQXd1X96JqoDm0ZreEQ_CA6/view?usp=sharing

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With the sparse specifics on the drone, there isn’t much to go on, other than the obvious that you stated.

Weight: 1.4kg ??? Hmm, basic rocket science here, lots of weight takes lots of power. Too much power (batteries) adds weight, counter productive. Commercial drones at half the weight get 10 times more flight time? Yours is too heavy. Those arms are one problem, so is the gimbal and camera and so on. Strip it down, see what you can get out of it naked, then add weight to see if you can live with it.

Batteries: 3S ??? Not for a craft that weighs in over 1.4kg. Going to need 4S or more.
25A at hover on a 2A battery? 12A @ 30min, 6A @ 15 min, 3A @ 7.5 min, 1.5A @ 3.75min and that is pure math, not the real world - you get the picture?

Props: Are they carbon fiber and not plastic? You want the biggest, stiffest props you can find that the motors will spin at a decent speed and lowest amp draw to optimize your flight time. Bigger props, lower kVA rating, slower speed, less amp draw …

Your experiments are just verifying what others have already stated, as they have also been down this same road. Best of luck.

3

So again, I didn’t have a clear answer, a solution, what should I do in this case? The drone works fine without the additional gear, if I use 4s my motors overheat, I have plastic big props, tried another type of props, no real difference, can try wood props but I don’t think that would help!

4

I gave you help based on the minimal specifics you provided.

Ok, what does ‘works fine without additional gear’ mean? How much does the craft weigh without the ‘additional gear’ and what is your flight time? Which battery ?

4s overheats your motors. Yep, plastic big props, they aren’t stiff enough, they bend and lose lift. Look at your first picture, see the big bend in the turning props? Wood is stiffer and would help, but probably too much weight for your wimpy motors.

Go check out https://www.ecalc.ch/index.htm . Plug in your hardware or the closest you can, see what it tells you. Maybe your configuration just won’t work as it is?

Again, Best of luck.

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5

Without any adittional gear it easily flew for 12-16 minutes! After that I added FPV, Camera, Landing Gear, Gimbal, LED’s and now it doesn’t even fly for 5 minutes!

I will try to replace the props this weekend and see how it performs!

6

A manufacture of custom industrial drones that I used to work with would joke that on these smaller drones it was “1oz/minute”. Meaning every gram of weight will have a direct and tangible impact on your flight time. My F450 will get 20-25 minutes on a 4S 5200mAH battery. But with a 1300mAH battery I get 10-12 minutes. The only change is the weight of the battery.

EVOs and Mavics have all been optimized for their performance. Their manufactures are a little generous with their estimates (especially DJI) but overall they will perform well. But they put a lot of time into the details of prop & motor combos and overall weight. If that’s your goal, remember you’re competing with some pretty big engineering departments with sizeable budgets. You can beat their performance, but you will need to be aware of all the smallest details and it’s probably going to cost you.

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What are your props, motors, frame and overall weight of your drone? @Allister

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With the 5200mAH 4S it’s 1150g, and with the 1300mAH 4S it’s 842g. It has no FPV, gimbal/camera, or landing gear. I might add FPV just for fun but, meh… I have 5" for that.

Motors and props are DJI. Motors are 2212, 920 KV. The props are the DJI 9450.

9

I really don’t know what you expect. But here is another example:
Quad-1732g
3508-380kV motors
13" CF props
6S 5000mah battery
~30 minutes of flight time which is almost exactly what eCalc predicts it would be.

There is no free lunch. The data drives the answer.

3 Likes
10

@dkemxr @llamatrails @Allister

Okay, I will probably rebuild the quad.

I don’t want to change:

  • RC Tx and Rx
  • Telemetry
  • Camera
  • Gimbal
  • Landing Gear
  • Apm Controller, old but functional

What I am expecting to change:

  • Motors
  • Esc’s
  • Frame

Can this make some improvement? If so, please link the items you have and know that work (I prefer amazon links), and thank you to everyone who helped!

11

Perhaps you should state if you are willing to pay for quality components before anyone wastes their time suggesting them. You have a poor quality frame, poor quality motors (collet adapters?), plastic props and those giant ESC’s suggest old school generic units. This looks like the cheapest kit of F450 parts you can purchase on alliexpress or similar. With a Flight Controller from 2015.

But to answer your question, build the quad I posted above. You can keep all that stuff you don’t want to change but for sure you would want to replace the Flight Controller. Why not, the battery will cost more than a decent FC. At 1400g it will fly for 35 minutes.

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Yes, I am willing to pay for good motors and ESCs, I don’t want my quad to overheat and fall again. What motors do you use? DJI motors? I can’t find the original ones and there are a lot of clones around them, especially on places like Amazon and aliexpress.

What ESCs do you have? Do all ESCs work with all motors or they need to be replaced together?

Fc is another story, should be replaced and probably will soon after I get it flying back again.

13

Never used DJI anything other than the Mavic Air I had for awhile.

I have used LD Power, Sunnysky, Emax, RCx and BetaFPV motors. Probably some others I have forgotten. For ESC’s now BLHeli_32 only which will do you no good with the old APM but they will work with PWM and are a better choice than the old generic ones you have. For ESC’s;, Spedix (many), Aikon, Airbot, ZTW.

All ESC’s work with all motors.

If you want long flight time with a heavier load build for 6S power with 13" Props (give or take an inch) .

14

First of all, I read that the maximum output of the motor should not exceed the maximum power of the ESC or it will overheat and burn.

I decided to go with this frame, I don’t know if it is good, but the weight is pretty good

I can’t find the motors you’re telling me, I have 2 3s batteries, don’t tell me they are useless now. Maybe I will try to build for less weight, 800g for example to use them, at least try.

15

This is obvious. You asked if the Motors and ESC’s had to be replaced together. They don’t, but I assumed you understood basic power requirements.

That’s a copy of the F330 frame. The largest prop you could put on that is 8". You are going backwards if you want long flight time which is what you posted about to start this thread.

Why don’t you buy a subscription to eCalc for $2.99 and plan a build?

16

Probably I’m wrong, but if you have smaller frame, you have less weight. Then less air resistance,
So with a less heavy battery you can probably achieve 15 minutes of flight time, or not??

As I can see, smaller drones most of the time have more battery life and flight time, a good example of this is the mavic series from DJI, it has more flight time than any of the phantoms, that are heavier and bigger!

Also I don’t want to buy another battery, 6s or 4s just to rebuild.

And please tell me the difference between free and paid eCalc

17

This is true and if you manage weight well you can get good flight time. I have a sub 250g 5" and with a 2S Li-Ion battery it flies for 25 minutes. But it’s not carrying a gimballed camera or much of anything else. So if you manage weight you could get 15 minutes of flight time yes.

You can’t can’t use the DJI craft as an example for the reasons (and others) that @Allister gave. You can’t even buy a gimbal like that, the frames are monocoque, some use Li-Ion batteries and everything is optimized. I had one, forget about comparing to DJI.

The free version is limited to a small fraction of the available components in the full version. Didn’t you check it out and see all the greyed out stuff?

18

Dont use that frame kit - it has the bendy arms and problems that you want to move away from!

This would be better:
https://www.amazon.com/FPVKing-500-X4-Quadcopter-Upgrade-Landing/dp/B087LT81C8/ref=sr_1_3?dchild=1&keywords=quadcopter+frame+kit&qid=1622669224&sr=8-3
or this if you need folding arms for some reason, but folding arms are another thing to go wrong


A bigger frame is more expensive, but you can run bigger props too, and that increases efficiency.
Master Air Screw make good props when you’re done testing and crashing

I can’t really vouch for either of those frames, I have not used them, but they are going to be stiffer and more versatile that the old flamewheel copies. If you are just going to have one good quad you need something where you can upgrade motors and props over time if you find needs are changing.
We bought one of these frames to see what it was like, and it’s been GREAT and we’ll buy more when we need to. We chose that one for the substantial arm mounts in the center plates.


We didn’t use the little upper deck, and the lower deck(s) are modified - but that’s what it’s all about!

Best idea is to get an ecalc subscription, it’s less than the price of a set of cheap props, and plug in all the values you can, like expected frame size, weight, battery, generic ESC size (like 40 Amps).
https://www.ecalc.ch/xcoptercalc.php
Run the Prop/KV wizard as a starting point. Then go through the extensive list of motors it suggests, click on some and see what Thrust-Weight ratio you get, 2:1 and above is good. You’ll probably need about to 3:1 if you’re going to add a bigger battery, gimbal and camera later (and all those extra radios and LEDs :slight_smile: )
Once you find a few motors that are likely to work, try to find if you can actually buy them somewhere, and if they fit your budget - if not keep searching.

If you stuck for motors, we’ve had really good success with the old NTM PropDrive motors from Hobbyking - now a lot of people will run screaming but we’ve got old 1000kv motors that have more flying-hours than Kingsford-Smith and had more crashes than I’ve had hot dinners.
And we’re currently using these big heavy motors with MasterAirScrew 12 inch props and 4 cell, great flight time and power to spare:


…yes there’s better things out there, but these are working.

We’ve used the Holibro tekko32 4in1 ESC with success, and any that Dave mentions will be good.

And get a flight controller where you can run DSHOT, ESC telemtry and Yaapu Telemtry - that means plenty of serial ports. You won’t look back.

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19

Hey, how about that great advice? Dispense with the obsolete hardware and posts and move into something supported. Plenty of people have things to add then…

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20

Or the Holybro X500 kit - it comes with everything except RC radios.
https://shop.holybro.com/c/x500-kit_0503
Yes - it’s expensive, but it’s known to work, no guessing. You can just buy the frame kit or individual parts too.
The only downside with the full kit is the “Pixhawk4” has some DSHOT limitations.

Edit:
Actually if you just want to go for flight time and a smaller frame then forget about carrying a normal sized sport camera or anything else, you’ll need a lot smaller camera like FPV size if any.
Either that or go with the bigger better frames that will carry a camera and other accessories.

One thing I’ve noticed, everyone starts out chasing long flight time, then after a while and some more experience you realize that all you really need for hobby use is 10mins. If you can’t do it in 10 minutes then you’re probably trying to do too much. Much better to go for reliability and a really good tune.
Now commercial and specialized situations - that’s different! A useful quad with 45mins flight time can cost a LOT of money.

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