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Help with Motor Selection

#1
Hello! I am new to the hobby! I was trying to find the best motor possible for both Pack B and Pack C compatible models. I have 20A ESC which seems to work with the motor below and 3S 2000mah, 4S 2000mah lipos;

Would this motor be ok to use in Edge540, Explorer, and SimpleCub?

https://www.promodelhobby.com/urun/a2212-980kv-330w-3-4s-fircasiz-rc-motor

and if it can be used; would it hover on Edge540 with 4S lipo(200g)?

Here is the specs of the motor:
Sunnysky-A2212-Fırçasız-Motor-Rc-Motor-DC-Motorlar-RC-Model-Uçak-Motor-Teknik-Detay.jpg
 
Last edited:

JasonK

Well-known member
#3
Can't answer if the motor would be ok to use, but I think I can read the spec sheet there.

The FT Edge 540 has a listed weight without battery: 1.5lb (680g) [I don't know if this is all up with recommended electronics, but am going with yes for now]. your stating that you want to use a 4S lipo with a mass of 200g -> which would put your total mass at 880g.

The spec sheet recommends a 9x5 or 9.4.5 prop and if I am reading the sheet correctly, it states that it can put out 1090 max gf of Thrust with the recommend prop. A quick google tells me that in 1 G (IE earth gravity) that is the force needed to counteract 1 gram of mass , so it looks like it is about 120% max of your total weight...

I recall reading some where that quads needed 2x or more (depending on the flight characteristics) lift to mass for stable flight. Given that this puts you over 100%, you have enough force to counter act gravity, however not a lot of wiggle room to counteract any mistakes.

Hopefully someone with some more experience can double check my math and intuition for you as that is just me trying to read your data sheet and doing some back of the envelope math.
 

JasonK

Well-known member
#4
I am also hoping that someone with some experiance can answer your question and confirm my logic or point out were I went wrong. I have a few ideas that I want to try out after I get some flight experience and this will be relevant.
 

BATTLEAXE

Well-known member
#5
I am also hoping that someone with some experiance can answer your question and confirm my logic or point out were I went wrong. I have a few ideas that I want to try out after I get some flight experience and this will be relevant.
I would concur with your theory, makes perfect sense. A 1:1 weight to thrust ratio would be where you would start to hover, and on 4s at 120% that would work. Mind you more power is always better. Maybe the same size motor but a higher KV rating with a 30-40 amp ESC. Even the battery with a higher C rating will make a difference there, it will max at 20amps as it is, a higher KV will increase the max amp draw some, plus you want a bit of cushion. I would say you want to max out the motor at 75% of the ESC rating, then of coarse is the burst rating. It will pull the Edge 540 no problem on a 9x5 or even a 10x5
 

Merv

Well-known member
#6
That motor looks about right for the cub, I doubt you will hover the edge with it. To hover you’ll want a 150% to 200% thrust to weight ratio.

Here are some guidelines that may help. It’s the total flying weight of the plane that you need, including motor and battery.

• 50 to 70 watts per pound is the minimum level of power, good for park flyers and lightly loaded slow flyers.
•70 to 90 watts per pound is perfect for trainers and slow-flying aircraft.
•90 to 110 watts per pound is good for fast-flying scale models and some sport aerobatic aircraft.
•110 to 130 watts per pound is what you want for advanced aerobatics and high-speed aircraft.
•130 to 150 watts per pound is needed for lightly loaded 3D models and ducted fans.
•150 to 210+ watts per pound gives unlimited performance for any 3D model.
 

"Corpse"

Well-known member
#7
That motor looks about right for the cub, I doubt you will hover the edge with it. To hover you’ll want a 150% to 200% thrust to weight ratio.

Here are some guidelines that may help. It’s the total flying weight of the plane that you need, including motor and battery.

• 50 to 70 watts per pound is the minimum level of power, good for park flyers and lightly loaded slow flyers.
•70 to 90 watts per pound is perfect for trainers and slow-flying aircraft.
•90 to 110 watts per pound is good for fast-flying scale models and some sport aerobatic aircraft.
•110 to 130 watts per pound is what you want for advanced aerobatics and high-speed aircraft.
•130 to 150 watts per pound is needed for lightly loaded 3D models and ducted fans.
•150 to 210+ watts per pound gives unlimited performance for any 3D model.
I'm saving your chart as a file. Thanks for the tips @Merv !
 

TDL

Active member
#8
What does "Hover on Edge 540" mean? If it means "hovering" in 3D terms and you are new to the hobby, I would said it is a long shot for a newbie to do that with his/her first 2 or 3 planes, especially on DIY ones unless you plan to use a fly controller (gyro). However, if you meant "limited vertical" then that Sunnysky works find.
I have a 3d trainer running Sunnysky 2212-10/1250kv, 30A esc, 10x4.5 sf prop and 3s 1000 30c. The all-up-weight is 537g (1.18lb) and it hovers just fine but still cannot get unlimited vertical. 3D setup is all about weight versus kv/prop selection. I personally don't think your setup (2212/980kv, 9x5 or 9x45 prop on 4s 2200) is the right choice for Edge 540. Maybe APC 10x4.7SF or 11x4.7SF (pushing a bit) on 3s 1500 would work but you need a 30a esc. With 20A you have no margin for errors.
Sunnysky 2216/880kv with APC 10x5E prop on 4s, or 2216/1100kv with APC 12x4.7SF on 3s is better choice for the Edge, but a overkill for the Cub and Explorer.
I would highly recommend this: forget about swapping electronics between a trainer and a 3d plane. Banging sticks for 3d flying is fun but my eyes get tired after 4 or 5 flights, I normally would take out a trainer or a warbird to relax a bit, that is the purpose for this hobby afterall, at least for me; and those electronics worn out fast on a 3d plane. I would definitely go with MG servos on 3d planes versus regular 9g servos which would last for long long time on a Cub. Motor/ESC/servos are pretty cheap today, batteries are not. All three planes you mentioned can use 3s 1300~1600. If you are constrained by budget, I would choose the right battery first.
Good luck!