Too much power?

SchrodingersCar

SchrodingersCar

Member
Just wondering - I've been testing a possible setup on ecalc, and it's hovering at ~30% throttle, and saying that it can support an extra 3000g payload. Is this acceptable for aerial photography? Or does it lead to problems with stability or otherwise?

I'm looking to upgrade my F550 with some of the extended aluminum arms, and some beefier motors and props (most likely T-motor MN3110 700kv or similar). The plan in the near future is to try to lift an LX100 and gimbal - once the camera's been tested a little more, and once I have the $$ - so in the meantime, it will still be lifting my go pro. Is overkill ever a bad thing? Or does it just mean longer flight times?
 

kloner

kloner

Aerial DP
theres a line you cross and alot has to do with how much power you ask it to make through fast forward flight that can cause stability problems, some aircraft work better than others in wind in those conditions. I usually try setting them up to be 40-50% hover throttle with the ultimate max AUW i'm targeting, when i fly them without a payload they dont really give a crap,,,, but if your at that low of throttle with a payload hanging under it making cg low, then it can cause stability issues, even more so going the other way and being say 60-70% i've seen some crazy stuff happen even just hovering....

this is 33% hovering on u7 and 18" prop.....
 
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SchrodingersCar

SchrodingersCar

Member
Thanks kloner, I guess I just mostly want to make sure I'm not looking at any catastrophic problems, I really only expect to be flying under-weight for a couple months, just to feel it out with a go pro before I do the camera upgrade. Do people ever add "dummy weight" to smooth out AP? Is that just plain stupid?
 


C

cootertwo

Member
Kloner, that there's got some balls! Off the subject a bit, but I've always believed in a big stock engine in a car, rather than the stock small engine tweaked all to hell, that constantly needs attention. Example, my 1980 Plymouth Fury cop car (318) that I stuffed a 440 into, sorta Blues Brothers style. What a blast!
 

SchrodingersCar

SchrodingersCar

Member
Even though on paper it's fine, my poor f550 with the stock e300 just sounds like it's struggling to keep up at times... It might be totally psychological, but I suspect I'd feel a lot more confident flying if I slapped a v8 on this sucker...
 

gtranquilla

gtranquilla

RadioActive
Schrodinger..... where went the cat?

I am following the same strategy, i.e., test out the 3 axis BGC with GoPro on my Octo until I am satisfied with overall functionality before moving up but now with the new GoPro4 Black might stick with the lower AUW....a while longer.... makes the Octo look like overkill..... might have to add a couple more GoPros to increase AUW.

I was under the impression that disk loading that is too low, allows wind gusts to have too much control over FC and/or RC control. Also that the ESCs are operating outside their optimum efficiency range, i.e., get too warm when running below mid throttle for too long..... sounds counter-intuitive but that is what was stated.

BTW - Does Heisenberg's Uncertainty principle apply to DJI A2?
 

kloner

kloner

Aerial DP
theres theory and theres proof..... it was 92 degrees in the dark and that was my very first 80 amp/u7 flight so i locked in on taking temps, if i remember right it was less than 10 deg over ambient and when the wind came up later it didn't make much a difference....
 

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Gary_In_PHX

Member
As a newb to this hobby, this arrangement is in the same vein of what I was trying to plan in my head.

I am thinking of "future proofing". By building for more lift than necessary, I allow myself the ability to modularize/modify the payload. Maybe it's counterintuitive with multirotors, but normally, a better power to weight ratio is a good thing.
 


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Gary_In_PHX

Member
kloner said:
the biggest problem is it costs more to crash and you hurt more things doing it...
Click to expand...

Is that because of the potentially better/more costly components to gain the P:W?, the potentially higher speeds upon impact? It seems like with less mass, the structure would be more likely to take a hit and survive.
 

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Gary_In_PHX

Member
So if I am understanding what you are saying Kloner, a Multi with an approximately 30% of throttle hover in full flight trim is bad because of the low center of gravity in effect making it top heavy like a weeble.

This is because the wind acting on the "platform" that is the copter area between the rotors provides makes has a mechanical advantage and the slower props have to catch up and then overcome the rotation to remain level. By using a faster hover spees the props are able to respond more quickly to changes in position by changing rpm with less rotational mass.

Sent from my phone using pixie dust and magic unicorn farts.
 

kloner

kloner

Aerial DP
at 30% your a bit like leaving a stop light in 2nd, will it do it, yea, but the power bands not there to effectively deal with turbulence like one at 50% would be able to manage
 

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Gary_In_PHX

Member
This is the same reason why large powerful engines are no longer used in super high performance racing and hypercars.

It makes sense once you can get your head around what is happening in the motions of the multicopter.

Sent from my phone using pixie dust and magic unicorn farts.
 

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edgarmillennium

Member
When I first designed my hex , it was with 12" props 690Kv and 4s batts. It is s F550 with the aluminum arms. I had very bad stabilty issues due that it was over power. The DJi are set to hover when control is at 50%, so when I hit %50 on the radio it still wanted to go up. So the Controller slower them, but it was so slow that was very difficult to maintain level performance. Sometimes it was close to flip. I had to reduce props to 10" to get it to flight easy.
 


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