I have a 3" Armattan Japalura quad with Armattan Oomph Titan Mini 1407/3650 kV motors, about 300 grams AUW with a 4S 850 mAh battery.  I love the way it performs and it's a really fun quad to fly.  Now I'm getting ready to build another 4S 3" quad.  It's going to have a DJI Air Unit, so it'll probably be a little bit heavier than the Japalura.  Do you folks have any advice about choosing a 1407 vs. a 1408 motor (or do you recommend a different size)?  I'm currently looking at these two options:

BrotherHobby Tornado T1 1407 3600Kv Micro Motor
iFlight XING X1408 3600Kv Micro Motor

I mainly want acro performance, not cinematic cruising.  The quad won't be carrying a GoPro or other HD camera.  I'll rely on the Air Unit for video recording.

Xing 4214.

Dont listen to all the jealous haters.
It will fly awesome. They dont want you hitting trans-warp-9 and breaking out of the simulation.

if you like how your quad allready perform, you might get close with different props on the same motor.
higher c-rated battery could compensate aswell a bit.

if you like to use the airunit rater than a vista, you will need to deal with the weight, you only will be able to get close...

you could also try to add bigger motors like 1606,1805 or 2004.
going more lightweight with the motor could also be a option to get close, a brotherhobby 1504,5 could probably do that, downside there will be limitations in propchoices.


show us your kind of flying with your 3inch, a video... to get close depends mostly on this.
do you bash/race/freestyle/cruising.... or what mix of it?

(15-Dec-2020, 12:38 PM)romangpro Wrote: Xing 4214.

Dont listen to all the jealous haters.
It will fly awesome. They dont want you hitting trans-warp-9 and breaking out of the simulation.

show us your build with 3inch and the named motors please

(15-Dec-2020, 12:38 PM)romangpro Wrote: Xing 4214.

Dont listen to all the jealous haters.
It will fly awesome. They dont want you hitting trans-warp-9 and breaking out of the simulation.

Meh.  I want something with a little more punch.

(15-Dec-2020, 03:58 PM)hugnosed_bat Wrote: if you like how your quad allready perform, you might get close with different props on the same motor.
higher c-rated battery could compensate aswell a bit.

if you like to use the airunit rater than a vista, you will need to deal with the weight, you only will be able to get close...

you could also try to add bigger motors like 1606,1805 or 2004.
going more lightweight with the motor could also be a option to get close, a brotherhobby 1504,5 could probably do that, downside there will be limitations in propchoices.


show us your kind of flying with your 3inch, a video... to get close depends mostly on this.
do you bash/race/freestyle/cruising.... or what mix of it?

Thanks for the advice.  I'll definitely use the Air Unit, because it is already sitting in my parts box.  (It's a long story, but I ended up with an extra one.)  I'm tentatively planning on using the NewBeeDrone Whirligig 3" frame, which they say is "Design[ed] to work best with 1404-08 motors, 600mah 4s", so I don't know if it would accept larger motors.  The BrotherHobby motor you mentioned looks interesting, but I'm pretty sure I want to have the standard 5mm prop mount.  I'll look at other 15xx motors, though.

As for the type of flying I do ... it's more about what I aspire to do than what I can do currently.  First, I want to be able to do bolder, more aggressive diving down this bluff.  The new quad will have Crossfire so I should have less fear of venturing out over the water.



Also, with a 3" quad I like to fly around my yard and through the trees, like this:



Hopefully, with practice I can work some acro moves into these kinds of flights.

PS - I edited the videos for my 6-year-old nephew, who thinks it's all about the crash at the end of the flight.

i couldnt see specs on newbeedrone, weight, arm thikness... did i miss the specs?

the framedesign seems leightweight and skinny to stay on a low weight, that let me beleive a motor like 1507 might be to powerfull and heavy, would need a more heavy battery aswell.
as the frame seems skinny, the uaw will be important for durability.

t-mount motors are generaly more lightweight, the props are aswell more lightweight. personaly i would choose a brotherhobby 1504,5 about weight, regardless the t-mount. there would be an emax rs1408 also lightweight... also t-mount but these would be my powerfull but lightweight choices to compensate the weight of an airunit. both choices should give torq to easy punch out of a dive.
the frame isnt made for performance overall, as a cruiser, 1404 might still work.
if you use the throttle like in the two videos, 1404 settup should still provide that power.

i would choose another frame if you like to have much spare power, 1507-1606 on a more rigid frame, 850mah lipos. it wont have the ability to be efficiency or nearly lightweight compared whirligig.

(15-Dec-2020, 08:29 PM)hugnosed_bat Wrote: i couldnt see specs on newbeedrone, weight, arm thikness... did i miss the specs?

the framedesign seems leightweight and skinny to stay on a low weight, that let me beleive a motor like 1507 might be to powerfull and heavy, would need a more heavy battery aswell.
as the frame seems skinny, the uaw will be important for durability.

t-mount motors are generaly more lightweight, the props are aswell more lightweight. personaly i would choose a brotherhobby 1504,5 about weight, regardless the t-mount. there would be an emax rs1408 also lightweight... also t-mount but these would be my powerfull but lightweight choices to compensate the weight of an airunit. both choices should give torq to easy punch out of a dive.
the frame isnt made for performance overall, as a cruiser, 1404 might still work.
if you use the throttle like in the two videos, 1404 settup should still provide that power.

i would choose another frame if you like to have much spare power, 1507-1606 on a more rigid frame, 850mah lipos. it wont have the ability to be efficiency or nearly lightweight compared whirligig.

Your reply is full of really helpful information and advice.  Thanks very much!

Yes, the information provided by Newbeedrone is pretty inadequate.  Albert Kim made a video about the frame, and it weighed 49.2 grams fully assembled.  I'm not sure about the thickness of the arms.  Several commenters on Albert's video said they thought the arms would snap at the screws in a crash.  I crash a lot (too many trees around here!), so that concerns me.  Here's a screenshot from Albert's video showing the underside of the frame.  It does look like the arms could break pretty easily.



I know of only three different 3" frames made for the Air Unit: this one, and two from iFlight.  If I went with iFlight I'd choose their DC3 frame, but I've seen complaints from several people, including Albert Kim, that they weren't able to achieve a good tune with that frame.

I'm starting to think that a 3" quad just isn't a good way to use my spare Air Unit.  I'm going to reconsider my plan and maybe build something different instead.

49g is pretty heavy, more rigid than i thought? probably the arms are 5mm? hmm... overall to heavy for my taste

more wingspan, longer blades will be better for carrying weight. maybee 4inch? there might be configurations where you could use the same batteries like on your actual 3". but nothing would be wrong with 5" for the airunit :-)


this would be an example of a 3inch with airunit and enough torq;
https://oscarliang.com/holybro-kopis-mini/

a nice flying space, i beleive a 5inch would be nice for that space.
5inch can be a bit more loud, on a low speed its not loud. more dangerous...

why not a 5inch?

(15-Dec-2020, 09:44 PM)hugnosed_bat Wrote: a nice flying space, i beleive a 5inch would be nice for that space.
5inch can be a bit more loud, on a low speed its not loud. more dangerous...

why not a 5inch?

Lack of skill? 

I do have a 5" Armattan Marmotte DJI Edition with T-Motor F40 Pro IV 2400 kV motors (4S batteries).  I tried flying it around the yard (I think with S4 props), but it just seemed much too powerful and hard to handle.  I was shaking after a few laps.  Maybe I can tone it down with some different props and/or a throttle limit.  Or maybe I just need more practice with it.  It's fine for the big empty 18-acre field at my friend's farm, but very hard for me to manage here at home with all of the tall trees everywhere.

What an awesome yard.

5" would be fine. Just reduce the angle on your camera so it is easier to fly slower. Personally I wouldn't worry about throttle limits etc.

a 5inch will cut these trees to a track over time and cost of props xD
maybe there can be improvements about handling on your marmotte?
if you have a 3s battery, give it a try, it will decrease the torq and accrelation. i enjoy flying 6s 1750kv motors on 4s batterys sometimes, close to 3s on 2400kv.
a throttlelimit is nice, 60% throttle range on 4s, change if you start to use the whole stickrange.
reduce the rates, add supperrate or some expo could also give presicion.

just start slow with a 5inch, you will crash a lot and progress fast around these trees.

(16-Dec-2020, 12:01 AM)UrbanJungle1966 Wrote: What an awesome yard.

Thanks, I am fortunate to live in a very scenic area.  I would love to watch a really skilled quad pilot fly around here.

Quote:5" would be fine. Just reduce the angle on your camera so it is easier to fly slower. Personally I wouldn't worry about throttle limits etc.

My camera angle is very low already.  I mainly have trouble with throttle control on the 5" Marmotte, but I think that can be improved with more practice and maybe with some tuning changes.

(16-Dec-2020, 12:11 AM)hugnosed_bat Wrote: a 5inch will cut these trees to a track over time and cost of props xD 

Good point!  And I can tell my wife I'm doing yard maintenance. 

Quote:maybe there can be improvements about handling on your marmotte?

Yes, definitely.  It had a big problem with low-throttle authority when I first built it.  That problem is solved now, by reducing the PWM frequency of the ESCs from the default of 96 kHz down to 24 kHz.  The BLHeli32 maintainer kindly made me a special build of the firmware to support 24 kHz.  The minimum in the standard release is 48 kHz. Changing the props from S4 to S3 seems to have made it easier for me to handle, too.  I reduced the filtering a little bit, but otherwise it is still on the BF 4.2 default tune.  So I think it could be tuned better.

Quote:if you have a 3s battery, give it a try, it will decrease the torq and accrelation. i enjoy flying 6s 1750kv motors on 4s batterys sometimes, close to 3s on 2400kv.
a throttlelimit is nice, 60% throttle range on 4s, change if you start to use the whole stickrange.

I like those ideas.

Quote:reduce the rates, add supperrate or some expo could also give presicion. 

Hmmm, I feel like the rates are OK, but I need to improve the throttle control--through tuning and/or more practice.

Quote:just start slow with a 5inch, you will crash a lot and progress fast around these trees.

OK, thanks for the advice and encouragement!