Sub 250g 5 inch

By Cheredanine on Aug 03, 2017

7 1,420  12 

So faced with more impending drone restrictions in the UK I thought I would try building a sub 250g 5 inch quad.
The frame is not a full stick but 4x 4 inch arms (not a typo, the 4 inch arms allow 5 inch props in this config) and three of the small plates, I tried various standoffs, the pictures show 20mm but in the end have gone for 15mm. I could have saved some weight by using the kisscc fc but wanted tie asguard for current monitoring. The power system uses an xt30 (had to shorten lipo leads and change the connector. I have a set of rotorgeeks 1407 2800kv to test with also, will be trying various lipos in the 650-850 mah 3s and 4s to get the best flight times and performance
(Photo on the scales is auw with tattu 650mah 4s at 219g)

Edit: blew the fc (human error), replaced and fitted with 2800kv, second photo showing with optipower 850mah 4s (shortened leads and xt60 replaced with xt30)

Video below shows full flight with 850mah 4s, gf 5030 and rotorgeeks 1407 2800kv
About 6 mins flight time flying like that, top end not up with fastest racers, but not bad

Tried racekraft 5038, less efficient, didn't notice flight characteristic improvement, (about 1 min less flight time)
Then tried 650 mah (still with the racekraft, lost another minute flight time and pretty bad voltage sag, will try 650mah with 5030 next.

Switched to 3200kv, flight time with 5030 - 5 minutes, more speed, certainly plenty for acro, although wouldn't match top end 5 inch racer, cornering though is very quick (less inertia I suppose), in theory I could go higher kv and sell a bit more flight time for more speed, however voltage sag is pretty steep already, don't think 850mah would cope well with higher kv, this seems to be the sweet spot

I must say a big thanks to EngineerX for his motor tests data and extended conversions on motor choice

Note current monitoring not set up
Stock pids and filters

And with 3200kv, I am not a serious racer, but pushing the speed, still haven't bothered tuning, motor 4 has developed some vertical play after crashes, but this gives an indication of speeds, it can do faster, trick it to master its tendency to gain altitude
4 mins 30+ flight with juice still in lipo on landing (I know it's not Charpu, trying to give evidence of capability of quad, not the pilot :)

Tried hq5045 however two issues- firstly weight, even with my lightest 850mah it was 251g, secondly although the motors can handle the props, the lipos can't handle the amp draw, anything in the top part of the throttle produces lipo warning even on take off with a full lipo.
Then tried a set of carbon hq5045 and they were much better, lipo can just about handle, need to shave a gram off the weight and replace a motor that dies today in a crash. Below is a (short) video demonstrating speed using 5045 on 2800kv, flight time flying like that is about 3 mins 30

Hq5040 carbon/nylon:

Using 850mah 4s on 5 inch using rotorgeeks 1407 (other manufacturers may give slightly different results, testing done with carbon-nylon or glass-nylon, on occasions I used pure nylon performance was worse as was efficiency
For acro:
3200kv or 2800kv with 5030 is excellent with huge flight times
For racing:
2800kv with 5040 is best
Either with 5045 is a close second but has slightly less too end and bit of a plateau on throttle, 3200kv also pushes the lipo somewhat
In either case 3-3.30 flight times


Part List


The Stick (3 builds)

Flight Controller

Asgard V2 Flight Controller (integrated Omnibus F4 FC, 4x 24A Dshot ESC, OSD) (2 builds)


4 x Rotorgeeks 7075 Series 1407 3200kv (6 builds)


GemFan 5030 5x3 CW & CCW Propeller Pack Of 16 In Black & Red | Drones Direct
See Site

FPV Camera

Runcam Micro Swift CCD 600TVL Camera - Orange

FPV Transmitter

TBS Unify Pro 5G8 HV 5.8GHz Mini FPV Transmitter Race (SMA) (335 builds)


TBS Unify Pro 5G8 5.8GHz Linear Antenna (3 builds)


FrSky XM Plus EU-LBT 16CH Tiny Receiver with SBUS (5 builds)


Tattu 75C 650mAh 4s 14.8V Li-Po Battery (3 builds)


Optipower Ultra Racing Drone Pack 850mAh 4S 14.8V 50C OPR8504S50
See Site

Misc Parts

Titanium M3x6 button cap screw (2 builds)

Misc Parts

Aluminum M3 locknuts (2 builds)

Misc Parts


Misc Parts

Titanium M3x16 button cap screw

Misc Parts

Search - Camera mount
See Site
Show stores (7)


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GBFPV   Aug 10, 2017  

This is very interesting. Would like to know max flight time when available (and the type of flight you did). Is it for slow flying or racing?

Cheredanine   Aug 10, 2017 

The blown fc and motor held me up for a bit but intending to get flight times using both sets of motors for 650 and 850mah lipos, 3 and 4s, and where possible try a few different props. I will add details here together with flight times as well as some dvr footage so you can see the flying style for the flight time (then you are not at the mercy of how good I think I am in my own head :))

Querk   Aug 03, 2017  

I'm not sure if pirofliprc ships internationally, but they have 1407 2700kv. I think it would be perfect for this build

delta_fpv   Aug 05, 2017 

they do ship intl and to my country (the netherlands) its a fixed 12 dollars

Cheredanine   Aug 05, 2017 

Pyroflip ship internationally, however their motors are brother hobby rebrands, whilst they are excellent motors, they are 1.5g more weight each (and I believe that is without the lock nut so more like 2g) than rotorgeeks, which means an extra 8g overall. With an optipower 4s 850mah 50-100c (97g) this weighs 248g, putting the pyroflip motors on would push it over the 250g limit (the odd gram here and there is a killer)

SadisticLeprechaun   Aug 03, 2017  

This is very interesting, I didn't think a 5" quad was possible under 250g. My 5S batteries are 170g so . . yeah, this is cool. I live in the USA and a recent lawsuit (Taylor vs FAA) nullified the restrictions for registration for now, but this is good to know. This quad looks a little fragile :) so I am curious how it holds up to flights over time. A video would rock!

Cheredanine   Aug 03, 2017 

Hi mate,
It looks fragile, everyone who has seen photos says that, but the arms are 5mm, they have less flex than many of my normal 5 inch quads, on the whole it is very strong, although crashes will tell :), camera is more exposed than I would like, but largely protected by the arms

Will be testing various different lipos and props, as well as switching to the 2800kv motors at some point for testing, try and find the sweet spot for flight time and performance, will upload some flight footage during testing

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