I want more flight time!

[Scratch]

...and no I'm not talking about that Harlem Globetrotter that was on The Amazing Race.


I'm talking about with my quadrotor. Right now I have an H-Quad with DT750's, 11x4.7 props and. 2200 3S 25C Lipo.

I'm wondering what the "recipe" is for a long flight time multirotor. Here's what I'm thinking.

Starts with big rotors
Need big motors to spin those big rotors
Need bigger ESC's to handle the more power
Need bigger battery
Lose some weight, like carbon fiber frame and props.

I've seen videos with 60+ minutes on a quadrotor. I'd like to get 30-40. With a GoPro, and FPV equipment. Does anybody have a proven design and parts list they know of?

And what are the trade offs?
I know it'll be a physically larger MR, but anything else? Like less battery life or something....?

 

[c172ae]

Low KV and props with large diameter and shallow pitch is a really good idea

 

[e_lm_70]

A guy in austria with 26" prop made over 2hours of fly time.

The best set up for long fly are 17x5.5 carbon prop and some decent 400kv motor on 3s or 4s

Ideal ratio between frame and battery shoidl be 50:50 ... so the battery shoud be as heavy as the rest for give best duration

The best battery for long fly time are some low C battery like panasonic liion, or some special 3c or 5c LiPo, normally used as TX battery

e_lm_70

 

[Tritium]

Major Tradeoff is MUCH greater expense. Big props are NOT cheap nor are big motors and esc's. Oh, did I also mention big frames as well. Woops, almost forgot big batteries too.

Thurmond

 

[Cyberdactyl]

Also remember, these guys getting extreme flight times are lifting just out of ground effect and static hovering. That's great to say you did it, but it's as boring as watching epoxy cure.

 

[e_lm_70]

The original 'record' from the guy that later made well over 2h with monster 26" carbon prop has been done with cheap parts:

5010-14 360kv motors with 17x5.5 carbon prop

These motors cost 18$ each, and the prop cost 8$ each ... not really cheap but not very expensive too.

Frame was a DIY carbon frame mainly just two carbon tubes smartly join together

With 5010 motors, the guy made 95min fly time on his DIY frame

 

[Stradawhovious]

The original 'record' from the guy that later made well over 2h with monster 26" carbon prop has been done with cheap parts:

5010-14 360kv motors with 17x5.5 carbon prop

These motors cost 18$ each, and the prop cost 8$ each ... not really cheap but not very expensive too.

Frame was a DIY carbon frame mainly just two carbon tubes smartly join together

With 5010 motors, the guy made 95min fly time on his DIY frame

Yeah, but you're talking about a multi rotor that has almost a 20sqft footprint at that point. I'm pretty sure Scratch's multi rotor is a wee bit smaller than that...

Assuming he's talking about his current airframe.

 

[Scratch]

No, I'm talking about building a newer frame. I'll keep this one as it is since it's smaller and already flies pretty well. But I'd be up for making a larger CF frame with bigger rotors, motors and everything. I'm up for spending more cash since this first one was so cheap to build.

 

[FinalGlideAus]

There is always a tradeoff in aviation. You never get something for free. Cost, complexity, size, power, load carrying capacity, maneuverability are just a few things that get effected by increased flight time. The big octocopters are getting 20 minutes plus but I think you are expecting too much of the technology right now to exceed that flight time if you are looking for a practical outcome. The weak link right now is battery technology. The Liion batteries have got a much better capacity/weight ratio but are limited to 1c current draw. Time will hopefully change things.

Those endurance copters are useless for anything other than the task they were built for. It's kind of like getting one of those solar powered planes and expecting it to be used as passenger aircraft.

If you are not after durability, are very careful with your design, prepared to spend a little extra money, actually spend time testing the best prop/motor/battery combo and are happy to forgo maneuverability, speed and power then 20 minutes is not of the question.

 

[e_lm_70]

Yeah, but you're talking about a multi rotor that has almost a 20sqft footprint at that point. I'm pretty sure Scratch's multi rotor is a wee bit smaller than that...

Assuming he's talking about his current airframe.

Nope ... the two copter were two different frame.

17" prop, need around a 100cm frame copter ... actually I made my own long flying copter, by using two square wood arms 1m each. ... I got a 10.000 5C 3S Lipo (4 x 2500mAh) ... but still did not fine the time to tune it and maiden properly ... but I did bench test the efficiency of 5010-14 motor + 17x5,5 carbon prop .. really impressive ... with little power (30w) they pull each motor around 500g with 50% power on 3S ...

Yes, it is quite big, but still manageable ... using folding arms it can be also relative easy to transport.
So, per my foot maths ... it is 9sqft footprint

Anyhow ... the trick for long fly time is :
- Use a quadcopter ... more motors will not make better fly time.
- Use the biggest possible prop
- Keep all the weight as low as possible.

If "toy" like Walkera and DJY 450 class can make 25min ... achieve 40min with FPV gears using smart selection of component it is not so complicated.

 

[Stradawhovious]

Yes, it is quite big, but still manageable ... using folding arms it can be also relative easy to transport.
So, per my foot maths ... it is 9sqft footprint

I get your point, but in my eyes even 3'x3' is impractical at best for the average hobbiest.

Scratch, if you're planning on building a monster like that, I get dibs on photographing the maiden.

 

[e_lm_70]

More info can be found here: http://www.rcgroups.com/forums/thumbgallery.php?do=threadgallery&t=1880665

I think there is a lot of good reading in this "closed" thread from EndOfDays ...