3.5” 4S sub 250 freestyle quad

[tawny seal]

so far I have just looked for all the parts online and put them in a excel spreadsheet, which you can find a link for here (or pic below):

https://1drv.ms/x/s!Alot2d7R2q4QqoN94pANDjPk4R-Q7w?e=mfBdnP

If anyone could help me to reduce the weight (see excel or pic) other than choosing a smaller battery), help me find a good VTX and/or check if everything is good and compatible, it would be awesome!

I'm planning to buy all the parts next month and assemble the drone.

[lone flower]

TBS makes great light VTXs, I can also recommend the Rush Tank Mini which is the same size and weight as the TX800

to use that antenna you will need an SMA adapter though

[tawny seal]

That adapter is included in the SpeedyBee TX800 VTX, hence I didnt put it in a seperate row

[tawny seal]

Rush tank mini vtx was my first option, but on a video it only delivered half of the output it said it was doing. Instead of 800mW it did 475 I think. Which is very disappointing and lost my trust in that vtx.

The speedybee TX800 vtx on the other hand performes extremely well

Kinda sad its out of stock everywhere (on EU websites)

[lone flower]

I have the TX800 myself, I don't have a clue why but when it's on 800mw it doesn't preform as well as my Rush VTX on 800mw, even with the same exact antenna setup

[tawny seal]

Thats pretty shocking to me

Il do some more research about those 2 vtx’s

[tawny seal]

Does the rush heat up really fast?

[tawny seal]

Would be interesting to see if you had something to get the power output of both

[lone flower]

any VTX does, it does have a heatsink though so its not a big problem

[tawny seal]

Yes ofcourse that’s normal, but not all of them heat up that fast

After doing some research, although the rush tank vtx outputs power is less, it seems to he getting better range than the speedybee one

Which I find weird but hey how it performs in reality is what matters

So Il probably get the rush tank mini vtx

[lone flower]

The Rush tank mini and TX800 both have 800mw tho

[tawny seal]

Thats what they say

Not what is actually happening

(My facts are based on just 1 vtx, it could perfectly be that that one vtx is just not working and that I get everything wrong now)

From “Kremer fpv” his tests,

Rush tank vtx at 800mW does 650mW

While speedybee tx800 at 800mW does 1000mW

But he says the rush vtx filters the electronic noise a lot better

[lone flower]

makes sense

same reason why some AKK stuff is so bad even though it has a really high output power

[tawny seal]

Yes

I guess Il have to switch to a smaller battery and more lightweight frame to get under 250 grams

As 257 isnt ideal

Smaller battery saves me 10 grams,

Current frame weighing 58 grams is far from ideal as there are frames only weighing 48 grams or so. Although I really like this one and would rather prefer a smaller battery

[lone flower]

they dont say the weight but the Carnage 3.5 V2 is great

@long scaffold do you know?

[long scaffold]

Nope

[tawny seal]

Looks great except stupid me doesnt like the looks and therefore wont pick it

[lone flower]

looks nice to me

[tawny seal]

It looks nice yeah and as I am more into a racer quads performance I do not like their design that much sadly

[graceful geyser]

you can save quite a bit by going AIO instead of a stack

if you prefer large pads, diatone has an AIO too, not the lightest for an AIO but still much lighter than the stack

weight specs also are rarely accurate it seems, every frame I had so far is heavier than specified and thats not even including stack screws, damper etc

[tawny seal]

You’re right although Im not really a fan of AIO’s

[tawny seal]

Thats my main problem. When buying a stack they dont tell me the weight with all the screws and dampers. Only how much the FC and ESC weigh seperately

So I assume about 5 grams for the screws

[graceful geyser]

Hmm didn't measure everything, maybe that works out. Are you sure about XT60 btw? 5g would have to be a very short cable and most batteries that size are XT30 I think?

Capacitor is another 2-2,5g

Oh, is it supposed to be 4S or 6S? The motors are 6S but your batteries are 4S

[tawny seal]

Motors are 3-6S

[graceful geyser]

Well yes, but 2450KV on 3,5" with 4S is probably a bit low? I have 3800KV on my AOS 3.5 4S

[tawny seal]

I chose the XT60 because the stack comes with one and spending €5 to switch to XT30 seemed a bit a waste of a money for me. And yes most batteries that size are XT30.

As this build will cost €450 already (for just the drone and 3 batteries) 💀

[tawny seal]

Then Il add that too

[tawny seal]

Hmmm I have seen some builds with a 2450kv 4S 3.5”

[tawny seal]

Which seems to be good

new total take-off weight is 265 grams, a smaller battery and new frame would make it 245

although I have seen someone with the same frame as mine get it under 250 grams

[graceful geyser]

I'd double check that, seems too low for me for freestyle at least and there is a 3450KV version of that motor too. rcinpower seems to have basically the same motors too btw (and available at DFR)

[tawny seal]

for racing you would recommend a higher kv too?

what exactly makes the higher kv a difference? More power? (with the expense of less flight time)

[graceful geyser]

I'm not a racer and that frame is probably not the best for that but yea probably. KV means how many 1000 RPM it can achieve per V, so at 16V (4S) it can in theory do 16 * 2450 = 39200 RPM at 100% throttle. More KV = more top end power and amp draw. Chris Rosser has a video about it if you like more details

Is it your first quad or do you have others to compare?

[graceful geyser]

5 Euro for like 4 grams (male + female XT60 vs XT30) is pretty cheap for sub250 - assuming you even find small batteries with XT60

[tawny seal]

I have a 5" quad with 2300kv motors

[tawny seal]

I'l watch that video from Chris Rosser then

[tawny seal]

I think I added the XT30 to it

Edit: nvm I'l add it now

[graceful geyser]

The tip speed is kinda what matters, so with smaller props you usually go for more RPM - at least thats what I learned the last 4 months or so, can be wrong ofc 🙂

[tawny seal]

That very much makes sense to me yeah

X220S 5" I fly with

With the 2300kv motors

I think I'l go for the GEPRC SPEEDX2 1804 3450kv motors then

[graceful geyser]

Those should work nicely I think. If it's your first build also don't forget a soldering iron and (good!) solder, DFR has some leaded solder which is much easier to use than lead free

[tired yew]

any reason for a stack over an AIO? Could probably save some g's there

[tired yew]

could probably go even higher

[tawny seal]

I have a good solder with bad soldering tips and TBS solder, I have soldered an EP1 Reciever on my 5" already without much problems

[tawny seal]

Heard that AIO's can be pretty fragile, also don't like the fact that on an AIO everything is cramped.

I like to use the space there yes but yes ur right I could save some grams.

[tawny seal]

That probably is a yes?

Also higher = more power? (I don't really care about how fast it drains the battery)

[tawny seal]

Currently watching this one

https://youtu.be/uvyi6hPIt8w?si=rpPlYIgoHOp2dw99

[graceful geyser]

It can get pretty complex and deep 😄 Easiest to orient on other builds that work, I'm using 1604 and 1404 3800KV motors on 3,5" and think thats fine, iFlight BNF ships with 3100KV

[tawny seal]

Would like to use 1804 ones

Although the 3450kv geprc aren't available on droneshop.nl or done-fpv-racer.com

I like them since they are completely black but these gold black ones wouldn't look bad either

[lone flower]

RCInPower is really good

[tawny seal]

Il get those then

Was a bit skeptical about those motors as I didn't know the brand

They look very clean ngl

[tawny seal]

Any AIO's you recommend?

Possibly with a barometer

Doesn't need to be cheap, it needs to be high quality and durable

[tawny seal]

Switching to these means I'l save 4.8 grams which is huge

(in theory)

[graceful geyser]

rcinpower is one of the most premium brands (I actually have the 1804 2450KV on the way for a 6S build), but weight is probably more measuring difference than real. I have one rcinpower 1804 2450KV here and it is 13,45g with the full cable length

"with cable" means with 2cm cable for some manufacturers xD

[tawny seal]

13.45grams is pretty dissapointing

If the 3450kv is 13,45g aswell that means I won't save any weight (so I can forget those 4.8 grams)

It comes with a 3cm cable they say, although I find that pretty short but idk If that's a normal length

On the website it says it weighs 12 grams, both the 2450kv and 3450kv, so seeing yours weigh 6 grams in total more is pretty dissapointing yeah

[graceful geyser]

It comes with 14cm cable and thats what I measured at 13.45g, you'll shorten that on a 3,5" and probably get down to 12.5 or something like that

[tawny seal]

https://youtu.be/YkFSf8gRvao?si=2jUJURL1NYtHOlHk

Albert Kim his motors are 11.8 grams when he weighed them

[graceful geyser]

Sadly you can't really trust any manufacturer weight specs as they all measure differently

[tawny seal]

14cm cable is very long yeah, will definitely be cut and save 2 grams per motor

[tawny seal]

The 12grams on their website is with 3cm wire but again that seems to be pretty short in my opinion

If I can save about 4.8 gram on that and reduce battery to a 650mah I would be under that 250 gram limit in theory

I'l try to look into more detail tomorrow for each component to see where I can save some more weight

[graceful geyser]

I suggest to leave some headroom and maybe start with one battery if sub250 is important. I'm trying to perfect my 3,5" builds for weeks and it's really hard and everything weights more than it seems xD even solder weights a bit

[tawny seal]

Yeah I'm scared to leave some headroom and round everything up as that is how I get faster to that 250grams or up

[tawny seal]

https://1drv.ms/x/s!Alot2d7R2q4QqoN94pANDjPk4R-Q7w?e=mfBdnP

I have updated the excel spreadsheet, updated the motors and selected the smaller battery.

Still 5.5 grams overweight but if the motors are 12 grams each and some other stuff is a few grams lighter then it would be under 249.

[tired yew]

Airbot G4 35A

https://www.vitroidfpv.com/articles/reviews-airbot-fenix-g4-am32-aio

[tawny seal]

Using this AIO (just the board) would save me 3 grams compared to the Mamba stack.

But maybe shorter screws and other stuff would save me a few more grams too

[tawny seal]

maybe a weird request.

But I could buy all the parts escept the diatone stack. If I have 20 grams over I can safely use buy and use the diatone stack. In case not I'l buy an AIO.

Although it would be very helpful to see someone have the full weight of the diatone mamba stack posted somewhere.

[graceful geyser]

Do you know of any shop in EU or from China that sells them? Otherwise it's like 135 euros and weeks of waiting for us in EU sadly

[tired yew]

they ship them from their warehouse in China very quickly

[graceful geyser]

Oh I thought they ship from US, so better chances to skip customs I guess 😄 Might give it a try then, it sounds pretty good

[woven bone]

Is the whole idea of this to build the quad, or to have a sub250g 3.5" capable of freestyle acro?

If it's the building of the thing, press on, I like the cut of your jib.

If it's the latter, why not just buy something like a Crux35 and some 850mAH 4s packs and get to flying?

[tawny seal]

The idea is to get a sub250 3.5” capable of freestyle acro yes

The sub250 and 3.5” has its reasons

[tawny seal]

Part of it is building it and the other part is to have a custom build fpv drone with my own specs that I would enjoy to fly for many years

But you are right, sometimes I wonder too why everything has to be this complex and why I would not just get a Crux35

My second quad would actually be a 7”. But that’s pretty big and so far I dont really see any reasons to get a 7” over a 3.5”.

7” is nice for some very long range but the laws here do not want me to fly further than 150 meters anyways, its also big and heavy, not really easy for transportation and is a bit more expensive than a small 3.5”.

Since I have a 5” I can use that for long range as it uses ELRS and a 600mW VTX already.

[woven bone]

Crux weighs about 90g for the analog version without battery, and you'll get about 15minutes playtime on a 850mAH CHNL Ministar.

And it'll be waaay cheaper.

Drone and two packs for under 200

What HMD have you got?

Also: going the crux route would give you a firm idea of how a drone with a certain spec actually flies so you can make a better decision on how you'd change it, if at all.

[tawny seal]

Its very lightweight yes, and cheap too

[tawny seal]

What does HMD stand for?

[woven bone]

Head mounted display, sorry, I'm a PC gaming nerd

Goggles, basically. 🙂

[tawny seal]

I kinda have in my head a bit how it will fly from watching videos and how my 5” flies. The problem a bit with my 5” is that I run out of space very fast since at 40-50km/h, a field of 300*300m is a bit small

[tawny seal]

Vrd2 pro, bought them in 2017 and just using them now

[woven bone]

Then you want something tame, arguably something on the underpowered side.

If you build it, don't try and build it like a racing drone. I have a sub250g 3" racing drone that will clock over 100mph. Waaaaay too fast for flying round the park (or similar).

[tawny seal]

100mph is crazy. What are the specs of it?

[woven bone]

Again, I'd argue the crux35 would be a wise choice. It's really nice and easy to fly, very forgiving, handles a light wind well. Good for smaller playgrounds.

[woven bone]

It's an old Diatone GTR349 Mk2

[tawny seal]

Yes I believe you, although for some fields I think it would be nice to fly a 3.5” as with my 5” I just run out of space honestly

[woven bone]

Eats a 4s 850mAH in under 5 minutes.

[tawny seal]

Hold on I have to eat

[woven bone]

Is frankly terrifying to fly anywhere near... Anything.

No worries, I'm off to bed anyways.

🚁

[tawny seal]

I definitely believe you. My dad thinks a small not too expensive drone is a wise choice too

Although Im not that type of person

[tawny seal]

That's pretty crazy for a little quad

[tawny seal]

https://1drv.ms/x/s!Alot2d7R2q4QqoN94pANDjPk4R-Q7w?e=mfBdnP

updated everything one more time, in theory it would be overweight by 2 grams but I have added about 1 gram for a multiple parts which would probaly be a few grams lighter when I get the quad and build it.

Will focus on my school exams which I have in 2 weeks before ordering and building the drone.

[woven bone]

That's a nice little frame that is. Wasn't sure at first, but that looks pretty nice actually.

[tawny seal]

I madly fell in love with it

[tawny seal]

I'm thinking to maybe not go from MMCX to SMA and then use a SMA Antenna as that is pretty heavy.

I could save 3-4 grams of weight by just using an MMCX antenna.

SMA Antenna: 4,5 grams + MMCX to SMA Cable (1-2 grams)
MMCX antenna: 1,9 grams

Although I have one problem then, I have no place to really mount a MMCX antenna on the drone or so that it doesn't sit lose and can move everywhere. The good thing about SMA is that the frame comes with a place to mount it there on so that the antenna sits rigid.

[woven bone]

3d print one?

[tawny seal]

3d printing it was an option until you realize you dont have a 3d printer and no one near you has one

Finding someone with a 3d printer isnt easy

I sadly so not know much about 3d printing and also have no idea how much certain things would weigh

[tawny seal]

Safest would be now to use the MMCX to SMA adapter and SMA antenna from my 5” drone and put it on the 3.5” when I build it and see how much the total weight would be.

[woven bone]

I mean, where are you based? If you pay postage, I can print you out some TPU mounts for things. Not claiming super high quality, yet, but still, the offer's there.

[tawny seal]

Belgium, West Vlaanderen

[woven bone]

Pffft, ez. 😉

[tawny seal]

Where are you from?

[woven bone]

UK. Sheffield atm 🙂

[tawny seal]

Hmmm, dont really like buying from UK since they left the European Union

Since then I basically stopped buying from the UK

Only doing Dutch/French/German stores now

[woven bone]

I totally agree, on the whole Brexit thing, my country are fucking stupid.

Equally, I'm not a store or doing it for any profit at all. It was just a friendly offer to help out.

[tawny seal]

I appreciate any help ofcourse, just a bit sad considering the location

[woven bone]

Me too. The idiots that inhabit this island infuriate me.

[tawny seal]

I just ordered the 650mAh 4S XT30 dogcom battery where on the website it said they weigh 82 grams.

I just received it and it weighs 75 grams. That means 7 grams less than expected, that's huge