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3d - Printworx

Printing 3d Forum

Help choose new motors for 4inch quad.

Started by atomiclama, Tuesday,June 13, 2017, 13:46:58

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OK just thinking out loud about my next motor choice for my 4 inch quad.

Would like ~20g in weight or less.
Mainly for speed and agility.

Brother hobby
or some RacerStar ones

Never used motors this size but they seem to have good reviews.

Current motors are DYS jobbies and ran well but are no longer available.

So these

I';ve also used some sunnysky 2204 2300KV motors but they are lacking top end speed so could try some higher KV but needs to be light.

Decisions decisions  ::)
Wasdale X, Ow that hurt


Unless you are building a hyperlight floss I would look at 1806

I would suggest brother do some, I think tmotor, xnova, Armattan, etc etc


4" prop quad,surely you would need something bigger than 1407?i run both brotherhobby and racestar 1407 on 150 frames with 3" tris and both ate fast but 4" props requires something bigger surely?

Would have said 22xx for power and spin 4" tris?

That said i am considering the new brotherhobby 1608 but they would be for 3" on a small frame round 150.

I just put the geprc leopard together with a set of racestar 2206 on 4" tris cos thats the max size of props the lx4 can fling,hovers and punchs good but need a vtx to go fpv.

Racestar have 2306 or something,thought someone said they did 2405 or something,cheap but cheerfull motors perhaps?


The problem with 2206 etc is the weight ~30g per motor

That';s an extra 40g on a 250g quad that I';m trying to reduce the weight on. no no no.
Wasdale X, Ow that hurt


Tuesday,July 11, 2017, 09:40:17 #4 Last Edit: Tuesday,July 11, 2017, 09:46:21 by Cheredanine
Hi mate, so working with a couple of manufacturers trying to produce under 250g 4 inch racers so have a bit more info on this, although by no means at final stage. (But definatley revise my previous answer)

If I wasn';t going for sub 250 and was running 4 inch, the motors I would be running are these, hands down, no question:

Generally if you want light, it';s 1407s on 4s with 4inch, mostly non bullnosed 2 blades
Motors typically used include:
Brother tornado 1407
Rotorgeeks 1407
Xnova 1407
Hyperlight 1407s
I am looking at Armattan oomph which may be a good choice.

The kv depends, the 4 inch are pushing it, although seen light 5inch on some of those, so the more aggressive the prop, as a general rule, the lower the kv. Bullnosed props are a bad idea due to terrible efficiency, they drag too many amps


I';m currently running 2204 quad blades on the front and 1806 triblades in the rear.

Still can';t make my mind up what to do with it.
Want to go light but the frame is an indestructible brute and a bit too heavy.

Also my attention has wander over to my larger quad which I';m enjoying more at the mo. Got a few more motors to destroy before I need to replace them.
Wasdale X, Ow that hurt


5 inch is the sweet spot for me, absolutely, the 250g thing is simply to avoid regulation, in the us sub 250 doesn';t need to be registered, in Canada the generally accepted version of the law is it is almost impossible to fly self built fpv over 250g legally, EASA are gonna crap all over self build over 250g in Europe including uk, requiring pilot and drone registration, pilot passing online test, there are also comments about technical controls, (geo fencing, altitude limits) which at least add weight to a 5inch and altitude limit is impractical - it';s fine on a phantom that is always the right way up but to cut the motors when you are inverted may effect your ability to recover


im running 1407 brotherhobby on a 4" setup using gemfan 4045 bi props and 4s 850mah 75c Acehe batteries,

AUW 290g power to weight on paper just over 10:1

and its a monster,

Tried some dys tj4045x3 and they haul butt, but the bullnose just eat the amps.

if you do use the 1407 keep it light,

1806 I would go for the X-nova they are very nice and provide good power.

Look at the F20ii T-motors. they are 1408 size.
Cost of ongoing battle with Gravity, .........:( Don't Ask :(...........

Typhoon H
Rotorious Rad 5", Gat 4" 1407's on 4s
Rotorious RIP 120 BL, Rotorx 1105b
Taranis Q X7 with hall gimbals


The f20ii are a slice over 16g with wires (but no locknut)
Xnova don';t have indication of weight with wires and lock nut, I am a big fan of xnova for smooth and they generally do decent power but not the top end and not the lightest.

Best power out of 14xx is oomph but quite heavy (18g with all)
Best 14xx for weight with second best power rotorgeeks, come in at just under 15g all in, also a wife selection of kv

But if you are just after power those 2204 from pyrodrone are the way to go