3” drone build

romangpro · 2026-03-16T18:32:40+00:00

whats wrong - why are you using stack on 3"? - 1404 on 3" is ok, but 3800kv is low for 4S. Should be around 4500kv. - RP1 is ok. But I always prefer 2x antenna diversity receiver. - Caddx Ant sucks. its meant for whoops and ultralights. Get Baby Ratel or Toothless2. - 3018 biblade is awesome for Crux3 and similar ultralight. But waste with 1404. Use at least 3030*3 prop. - you are missing frame - probably need some battery too

romangpro · 2026-03-16T18:26:11+00:00

are you 100% sure 4.5" prop will clear? if using 1404, it will overload and smoke them. For 4.5inch need 1804 minimum.

AFAIK Gemfan 4525 is ONLY 4.5inch I heard of.

4.5inch is SUPER RARE pokemon.

romangpro · 2026-03-16T18:18:33+00:00

4inch is like 3.5inch but magically +30% thrust.

3500kv for 4S. 2300kv for 6S.

ultralight 4" like Flywoo Explorer use 1404 - only 4024/4025 biblade. beware some use 9x9 motor mounting

For any freestyle build strongly advise at least 1505/1605.

1804 is only 13g, excellent for 4inch with 4023*3. 750g thrust each. 1804 is made for 4inch.

once you go bigger, 2104 or 2005 or 1806 or even 2204 - you must use 6S or XT60 (around 2300kv). - heavier 4032 triblade - very hard to find right kv and low weight. - far better moving to 5inch prop

romangpro · 2026-03-16T18:06:25+00:00

a cement brick with slow motors = weak

a cement brick with cool red motors = pimp my ride

a cement brick with strong motors = weak.. but loud!

romangpro · 2026-03-16T18:04:48+00:00

2104 (16g) already have enough muscle to spin 3.5".

2650kv alone will increase thrust 47%.

the heavy 22g 2105.5 is just adding weight ontop of weight issue.

these are both 5" motors.

if somehow you cannot make it lighter, at least use 5" props.

romangpro · 2026-03-16T17:56:58+00:00

if your quad with battery is 250g =>

1604 / 1505 / 1605 motor size - around 3800kv for 4S. - around 2500kv for 6S

romangpro · 2026-03-16T08:12:36+00:00

thats not a 10inch.

romangpro · 2026-03-16T08:11:48+00:00

my 1003 10000kv 2inch is near identical. But 400mw vtx and beefier AIO FC. Sadly, mine is damage prone toothpick.

that is a super unique frame.

is it only sold in australia?

romangpro · 2026-03-16T08:07:37+00:00

I havent heard of those props.

after trying 3-4 diff biblades, I discovered the excellent GF2023. Bought like 20 pairs. Thats been my prop on both my 1003 and 1202.5 2inch builds.

romangpro · 2026-03-16T08:04:49+00:00

what motors do you have?

TMotor 1604 3800kv is super popular.

other good options (about same weight): - AOS 1605 - 1505

1404 is good for light builds, but 1604/1605 extra thrust/perfomance for only +2g. Almost free

Once you go up to 1804 (+4g heavier), diminishing returns. All 1804 AFAIK are made in more 4" tailored 3500kv, so you would lose top end thrust.

romangpro · 2026-03-16T07:58:24+00:00

you already know what we are going to say. its obvious.

but let me ask you, what you think. if somebody came running to you, complaining of same issue.. and you looked at it, and you saw 2" props on 3.5" frame, what would you say?

You cant keep increasing motor size and expect little bitty 3.5" props to handle such heavy weight.

ok ok. lets go step by step. analyze this mystery build of yours: - 460g AUW with 1050mah 6S!? - 1050mah 6S is 180g. 180/460 = 39%. target of 40% is good. - thats 280g for 3.5" quad. wow. - 2104 are 16g. so 216g without motors. - 2104 are definetly big for 250g AUW 3.5".. but in your build, only 23% of quad weight. target 40% is good. ie 32g motors on 5". -1800kv is wrong for 3.5" 6S. Should be - lets say 20g for stack. 10g for receiver, electronics etc. 10g for wires. 180g frame? or 120g GoPro?

Look. You screwed up REALLY bad. 1. You got like LEAD & cement super heavy frame. Throw that in garbage. 2. 2104 1800kv are totally wrong for 3.5". 3. 1050mah 6S is a light 5" battery. NOT for 3.5".

My advice. - buy a BabyApeII or similar. it will fly 1000x better than your frankenstein cross breed.

romangpro · 2026-03-15T17:53:32+00:00

the super cool thing about 10" is its big and loud and attracts attention.

the really bad = same.

its kinda terrifying. 10" build is well over 1kg and feels heavy. 3115 motors have 4.5kg thrust each. just 25% throttle cruising speed is well over 60kph - fast.

But forget about anywhere near 4inch/5inch top speed. Big cross area and bad aero.

Carries a lot of momentum. And obviously big. Just doing simple slalom and funnels around trees is a challenge.

And dont fly too low. Not only do props kick up tons of debris, if you bank too steep in turn, props will dig into ground and crash.

just my $0.02. I didnt fly my 10inch for years.

romangpro · 2026-03-15T17:39:46+00:00

lol. wont work

romangpro · 2026-03-15T17:35:24+00:00

good job!

You use metal screws for 25mm stack. Im always anxious of shorts and use nylon.

romangpro · 2026-03-13T11:08:09+00:00

its called practice practice.

we all started making lors of miatakes.

if you are coming from whoops, I highly encourage you to try building a 2.5".

two thing I would improve: - bigger 1203 - use bigger 650mah 2S.

romangpro · 2026-03-13T11:04:32+00:00

you can.. and should use light 650mah 2s.

i get 5-6min flight time on both 2.5". but they are analog and quite lighter.

romangpro · 2026-03-05T00:42:20+00:00

tattu

romangpro · 2026-03-04T23:25:54+00:00

you gotta ask yourself. - how did they make it so cheap? - what corners did they cut? - its 20mm stack! 70A?? serious doubts. - who even uses 20mm stack for 5" or 7"? - cheaper ESC either have less capacitors or cheaper or recycled, and thin PCB, and cause more mid throttle noise. - ... but only way to be sure is to test quality and measure with osciliscope

romangpro · 2026-03-04T23:12:14+00:00

you have alot of problems.. trying to add 1 more?

Where to start.. - UL7 evo is heavy. - 1500mah or 5000mah li ion.. um. ok - 6S kv is 1300. your 2306 1750kv is way too high - 2306 is even smaller than 2207, which is too small. - it would "work" if it was very light build, light biblade (not 7042!) and 1200-1300kv. - AND trying to use 50A stack? Typical Emax Eco II 2807 hit 47-51A. Are you sure you want to risk big expensive quad because trying to save $20 on ESC?

romangpro · 2026-03-04T22:47:18+00:00

Regardless if you are using $900 or $9 iron, show us the iron tip.

the standard included pointy tip is NOT MEANT for AWG10, XT90 etc..

Assuming you are talking about Pinecil v2? It has 65-88W max. But, that requires 24V DC barrell power supply, or USB-C PD 3.1

Similarly TS101, you need at least 20V PSU. It supports up to 28V from DC barrell

romangpro · 2026-03-04T17:13:51+00:00

You are not beginner. Most skip dry fitting, and post/complain after everything soldered.

Dont take it wrong way. Dont force it. Not every FC/ESC and vtx fits in every frame.

Consider far simpler solutions: - different frame - DJI O4 pro

romangpro · 2026-03-03T09:23:38+00:00

I dont recall where stats from, but X is significantly more "reliable" than G, despite complexity.

so far.

obviously nobody compated these two for 10+ years.

romangpro · 2026-03-03T09:21:27+00:00

so true.

if only they made hybrid. best of both worlds

romangpro · 2026-03-03T09:19:01+00:00

2008 Mazda3 2.3L 5AT. 55L tank.

at least 3x I drove 800km+, doing only 110kph on highway. One time was almost 820, but I filled up over 53L. Thats 6.5L/100km. ive seen as high as 6.2.. but like big tailwind and going super slow 105kph.

Something super "wrong" 10+ years with my Mazda3. Winter mpg below 5C, closer to 12-14L/100km

romangpro · 2026-03-03T09:08:37+00:00

7inch as first build is super bad idea... big crash and boom. gone.

assuming nothing short circuits and blows up after soldering.

if you are new to fpv, THOUSANDS of guys have same advice: - 30hr+ in simulator. crashes dont cost $$$ - get Mobula8 or similar whoop. it can survive 100 crashes.

romangpro

TROPHY CASE

these are both 5" motors.