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Dec 12, 2019, 04:54 AM
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Sub 120g 5" (wo battery)


I hope this overview/guide will help others select parts and build ultralight 5".
Sub 120g thread title because want to fit 120g battery in 250g build, and too many "sub 250g" threads are dry weight, which is SUPER-COMICALLY-EASY.

Guide:
* must be full functional, camera fpv, but meant for freestyle, not racing
* durability will be compromised, but no homemade balse wood frame
* no weak sauce: XT30 (peak 60A) or 11.1V 3S.
* 500mah 65g battery makes 250g super easy ->
Build an Under 250g 5-inch Drone 😯 (11 min 9 sec)

* 5030 props need 27-30A @ 14.8V,

Frame:
--------------------------------------
"1407" 12 M2 motor pattern - looks very nice
url]https://www.amaxshop.com/index.php?route=product/product&product_id=1573[/url]
Armattan 185mm, but no canopy
https://armattanproductions.com/pages/kit_detail/885
Druckbar 25.4g
https://www.rcgroups.com/forums/show...t-5-inch-frame


FC/ESC:
--------------------------------------
20x20mm HGLRC F4 28A - 6.5g 35A burst
https://www.banggood.com/20x20mm-XJB...r_warehouse=CN

20x20mm HGLRC F4 40A - 8.9g BLHeli_32 50A burst (doubt) 5S!
https://www.banggood.com/HGLRC-XJB-F...r_warehouse=CN

26.5mm (save space) GEPRC 20A - 7.3g 30A burst (big doubt)
https://www.banggood.com/GEPRC-GEP-2...r_warehouse=CN

20x20mm Mamba F4 mini - 11.5g 25A burst - sufficient for 3" only
https://www.banggood.com/MAMBA-F405-..._warehouse=USA

20x20mm Racerstart 40A - 7g 45A burst, BLHeli_32!
https://www.banggood.com/20x20mm-Rac...r_warehouse=CN

Camera/VTX
--------------------------------------
Eachine TX04 25-200mw 5g
https://www.banggood.com/Eachine-TX0..._warehouse=USA

Eachine TX06 25mw 2.8g this is lie
https://www.banggood.com/Eachine-TX0..._warehouse=USA

Caddx Baby Ratel - 4.6g would need separate VTX
https://www.banggood.com/Caddx-Baby-...r_warehouse=CN
For reference, Caddx Turtle is 12g+ which is too heavy

Receiver
--------------------------------------
pretty much everything is about 1.0-1.5g
https://www.banggood.com/FrSky-R-XSR..._warehouse=USA

Capacitor
--------------------------------------
https://www.amazon.com/pcs-Panasonic.../dp/B073YQ8N55 1.8g


Propeller
--------------------------------------
5030 - 1-2g each?
https://www.buddyrc.com/propellers/5...prop/5030.html

=====================
Subtotal (rounding up): 55g
=====================

+ screws + solder + 4 motors (Part2)
Last edited by romangpro; Jan 30, 2020 at 10:09 PM.
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Dec 12, 2019, 05:24 AM
Registered User
Thread OP

Motors - need your help. Whats the best option for efficiency with 5"


I have followed sub250g 3" and 5" ultralight on many forums. Vast majority basically just put small battery.
I want to emphesize, too small battery will handicap your quad. Dont just stick 500mah on a 5"!!

2204/2205 motors with 500mah battery is as comical as inserting a 5L V8 inside a Prius/Civic, with same intake/exhaust/suspension.

Weight vs size (this is rough guide)
disk area in cm2 optimal weight
3" - 182cm2 80g
4" - 324cm2 160g
5" - 507cm2 280g
7" - 993cm2 600g
For good performance, you want AUW <1g/cm2.
Bigger props are more efficient and more forgiving.
On paper over 10:1 thrust to weight, but the props have to quickly change the momentum of your (heavy) quad.
Everybody in community already knows a 700g 5" feels sluggish.
Likewise, when you strap a gopro, a 250g 3" is all sloppy. Cheating with 3052 only leads to huge Amps and problems.

KV / Power Math
Ideally, we would run 6s, but no 15g small sub 2000KV motors. Stuck at 14.8V. Need sub 3000KV.
XT30 can peak 60A. -> 225W/motor, suitable only for small 3"
XT60 can peak 160A. -> 600W/motor

Battery and thus system power is proportional to size. Extrapolate
Code:
weight     mah        5sec        peak     Peak Motor Watts @ 14.8V)    
360g      3000mah     160A        260A      962W
180g      1500mah      80A        130A      481W   <- 14.8V tested by JB/others  Tattu R-Line 3.0. BEST CASE.
120g      1000mah      53A        85A      314W   <- 85A will kill XT30.
78g       650mah       35A        56A      207W
This is **rough** max of what LiPo tech can do. 6s is ofcourse 50% higher Watts and 50% higher weight.

Lipo C ratings are a HUGE LIE. Best case, Tattu 3.0 can only do approx 55C/90C peak
Thunder Power Adrenaline vs. Tattu R-Line | BATTERY TEST RESULTS (17 min 10 sec)

Mr. Steele and Le Drib try a "TRUE 175C" battery (13 min 2 sec)

CNHL 1300 and 1500 4S 100C | BATTERY TEST RESULTS (19 min 17 sec)


What does this mean?
For split second, the 1000mah cannot provide more than 314W per motor. Thats the max.
If big 2208 motors, their power is wasted unused.
If XT90 or thick cable, it will never use its potential, but always add its weight.
Doesn't matter if same weight, 6s 650mah, which will have same Wh, and thus same power.

A 120g battery is a sponge that can only squeeze out 314W per motor.

Powerful motors MUST have bigger battery.
Running 650mah battery on 2207 5". Vast majority of motor power never used!
Running 650mah on 3" high power 1408/1507. Still not enough battery!
650mah belong on 13xx/12xx on a 80g toothpick.

Roughly how much battery is needed? Motor weight x2.
8g 1204/1303 motors-> 65g battery.
17g 1506/1507 motors -> 140g battery.
30g 2207/2306 motors -> 240g battery.
And again, this is BEST CASE, brand new Tattu 3.0, sub 1sec peak.


Lets find best 15-17g motors for 5"

Motors
==============

1. BrotherHobby started it all with Avenger 1507
15.5g, 18g with wires 3000KV
https://www.banggood.com/BrotherHobb...r_warehouse=CN

2. 15.5g, 17.0g with wires, RCInPOWER GTS-V2 1506 - 3000KV - [email protected] and 110mohm
https://www.banggood.com/RCINPower-G...r_warehouse=CN
I bought these RCInPower for efficiency, and ability to handle 400W+.

3. 15.2g with wires. T-motor F1507 - 2700KV - 12N14P - [email protected] and 131mohm
https://www.banggood.com/T-Motor-F15...r_warehouse=CN

4. 15.8g with wires. iFlight 1507 - 3000KV - [email protected] and 208mohm
https://www.banggood.com/IFlight-XIN...r_warehouse=CN

5. 16.3g BrotherHobby VY1507 - 3100KV -12N14P - [email protected] and 137mohm
https://www.brotherhobbystore.com/vy-1507-p0102.html

6. 15.4g. XNova 1804 - 3100KV - [email protected] and 123mohm - > WORSE
https://www.xnovamotors.com/xnova-18...-motor-series/
1408/1507 have stator volume ~400. 1806/2204 are both about 500. 1804 is low 320.



Didn't quite make it - too low power for 5":
------------------------------
https://www.banggood.com/HGLRC-Flame...r_warehouse=CN
https://www.banggood.com/Hobbywing-X...r_warehouse=CN
https://www.banggood.com/IFlight-XIN...r_warehouse=CN
12g. 13g with wires. T-motor F20 - 1406 - 3200KV... looks good, right?
http://store-en.tmotor.com/goods.php?id=302
16g and can do almost 300W
https://www.banggood.com/FLYWOO-NIN-...r_warehouse=CN
Last edited by romangpro; Jan 31, 2020 at 12:05 AM.
Dec 12, 2019, 09:37 PM
Registered User
Thread OP
Bought 2x Tattu 1050mah 14.8V 95C. (120g).
15.5Wh.

predicted flight times....

EngineerX and Gal Kremer thrust tests of 1408/1507 motors and 5030 on 4S :

~16-17W for 60g thrust (hover). 3.7g/w
~29-36W for 150g thrust. 5.2g/w
~70-80W for 300g thrust. 4.3g/w

flying will be better. Also 3S would help.

250g @ 4g/w =62W... 15/62=14min
250g @ 5g/w =50W... 15/50=18min

problem is the 1A idle current... 10W+ before props start spinning
Jan 08, 2020, 05:01 PM
Registered User
On the tmotor 1507 what do you mean by only 2mm shaft?
Jan 08, 2020, 10:10 PM
BisDak2
humayraykinaon's Avatar
Quote:
Originally Posted by wiigelec
On the tmotor 1507 what do you mean by only 2mm shaft?
My guess is the inner shaft
Jan 10, 2020, 09:47 AM
Registered User
But the prop adapter is m5 for standard 5 props?
Jan 10, 2020, 12:17 PM
BisDak2
humayraykinaon's Avatar
Quote:
Originally Posted by wiigelec
But the prop adapter is m5 for standard 5 props?
Yes, but the inner 2mm is clamp with set screw.
Jan 10, 2020, 01:07 PM
Registered User
Thread OP
other option is BrotherHobby YV 1507.
I think the idle current and resistance is bit high.

Ideally a 1806 or 2204 motor, but weight is 20g+.

Our budget is only 120g. 20g motors means extra 20g.
Cant save enough from FC stack which is 6g.
So.... 15g 5" frame sounds ridiculous.

There is obvious weight problem solution... less motors -> 2 motors with bigger props.
Jan 10, 2020, 08:23 PM
BisDak2
humayraykinaon's Avatar
Can't wait to see it done.
Last edited by humayraykinaon; Mar 10, 2020 at 08:46 AM.
Jan 22, 2020, 08:23 PM
Registered User
Thread OP
Well guys. Boat made it over the ocean.
The parts are here. I measured:

Armattan 190 frame - 32.7g assembled.
RCinPower1506 - 17.2g

HGLRC 28A stack got lost in mail.
so Im using Racerstar 20mm 40A. - 8.7g
20mm F4 FC - 3.4g
Eachine TX06 (cam + vtx) - 4.6g!!

Thats 118.2g already!
and we still need propellers, standoffs, solder

To puthings in perspective, my 2207 MambaF4 5" build is 350g, auw 550g+

Backup plan.. 100g lowC 3S battery.
Jan 26, 2020, 02:02 AM
Registered User
Thread OP
Quote:
Originally Posted by romangpro
Well guys. Boat made it over the ocean.
The parts are here. I measured:

Armattan 190 frame - 32.7g assembled.
RCinPower1506 - 17.2g

HGLRC 28A stack got lost in mail.
so Im using Racerstar 20mm 40A. - 8.7g
20mm F4 FC - 3.4g
Eachine TX06 (cam + vtx) - 4.6g!!

Thats 118.2g already!
and we still need propellers, standoffs, solder

To puthings in perspective, my 2207 MambaF4 5" build is 350g, auw 550g+

Backup plan.. 100g lowC 3S battery.
too heavy.. maybe need lead free solder

≠====≠=====≠====≠=====≠
redid ESC soldering.. sucked up solder. wire strands exposed... but saved 1-2g. Maybe can suck up 1.0g more.

The 600uF and 470uF caps were too heavy..
almost 1.5g.. so 330uF it is.

I got beautiful M2 rubber standoffs... but the weight!! I cant afford over 1.0g.. so plastic standoffs and little clear rubber donuts.

Canopy (optional?) will be 2.5g. Ughhh..
Maybe take out 1 M2 screw per motor to compensate.

The OBVIOUS: trim battery and and power wires. Is 2cm enough? 1cm?

Extreme: trim motor shaft... just grind away until 1.5 turns left for locknut...

XT30 or going to AWG16 is big no no.. 100A+ is required.
Last edited by romangpro; Jan 27, 2020 at 10:52 PM.
Jan 29, 2020, 03:10 AM
Registered User
Thread OP
###########
# 139.8g dry #
###########

Remaining:

2.5g canopy
battery strap.
120g 1050mah Tattu 4s (slow china boat)


So just need to shave 12g.
Jan 29, 2020, 07:58 AM
Fan of just about anything RC
SoloProFan's Avatar
I wonder if those 1506 will draw 100+ amps anytime. These motors are also used on 3 inch quads, and max amp draw then often comes between 40 and 50A.

You might also try low profile lock nuts for the props, shaves off a bit of weight, though not that much, since you already use alu prop nuts.

Are you using 2 screws per motor, or 4? You can get away with 2 screws, with good thread lock.
Latest blog entry: For the love of the hobby!
Jan 29, 2020, 05:04 PM
Registered User
Thread OP
No. The calc says RCinPower 1506 3000KV, should draw 27A on 4s (400W) with the 5030 props, and around 1000g thrust.

EDIT
============
This is extrapolated from RCInPower and similar motors. Same size, KV, brand makes very little difference, worst case a couple percent (ie 83% vs 85% efficiency)

============

5040x3 will probably suffer.. I estimate 32-35A (500W), and up to 1100-1200g. => motor will certaily overheat at this level

In hindsight the BrotherHobby VY 1507 may be (lighter) better.
https://www.brotherhobbystore.com/vy-1507-p0102.html

Other options, that can handle 400-500W like T-Motor F1507 and Xing1507. But, max power is poor indicator.
Need to be able to rapidly change prop speed during maneuvers. Unless somebody discovers superconductive, or N66 Mmagnets, nothing beats wider stator. If it was so good and easy, all the racers would have done it already.. lol

In hindsight, limiting to bi-blade wouldnt be issue on a BrotherHobby 1806 :shruggs:

Im hoping XNova, Xing or Brotherhobby makes a sub16g 25% lighter 1806...

* Stubie shaft.
* square stator wire
* Drill holes in side of bell between magnets.
* carbon fiber base.
* hollow bearings
* heck throw $$millions$$ at Musk, and ot will happen
* 0.004 air gap
Last edited by romangpro; Jan 30, 2020 at 09:16 PM.
Jan 30, 2020, 09:53 AM
Fan of just about anything RC
SoloProFan's Avatar
Quote:
Originally Posted by romangpro
No. The calc says RCinPower 1506 3000KV, should draw 27A on 4s with the 5030 props, and around 1000g.

5040x3 will probably suffer.. I estimate 32-35A, and up to 1100-1200g.

Where does it say 27A for that motor? Is that static test? Peak, or continuous? Amp draw in flight is usually much lower than in static test. If you draw 100A regularly than the flight times on a 1050 mAh will be less than a minute. I doubt that is the case, flight times are more likely going to be much longer, so average current draw will be much less than 100A.
Latest blog entry: For the love of the hobby!


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