UltraLight sub 250g 5 inch build

By freerider101 on Oct 27, 2019

9  2,131  10

I've been inspired by sub 250g 5inch attempts over the net. My goal is not speed but more on cruising, efficiency and long flight times. It's hard to find ultralight 5 inch frames in the EU. So far, drueckbaer's frames are pretty awesome. This is my first ultralight build attempt. I'm currently trying out the kingkong 5inch biblade. So far, it seems quite good, though I believe that it's drains a bit too much current with more than 1second punch outs. And thus, sagging the battery voltage too much.

With the the items I used, these are the flight times I have:
GNB 3S 450mAH : 3-4 mins
Tattu 3S 850mAH : 5-6 mins

It handles extremely well. With the stock PIDs, there is only a tiny bit of propwash which can easily be tuned out. The quad is extremely responsive. So responsive that I need to reduce P's a bit and thus also improving propwash performance.

I haven't weighed the quad yet but it's pretty light. From the components, it should be around 150g dry, maybe less. I will constantly update my findings (actual weight, props, battery etc..) here if someone is interested.

First FPV maiden:

Subsequent flights:

Some links that helped me out..



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Jodie Froster   Jun 05, 2020  

So it's been half a year, you still fly this lil guy? I am curious about durability. I ASSUME it's pretty resieliant in crashes, due to the weight, but it has some REALLY thin spots in frame. How has your held up?

freerider101   Jun 09, 2020 

I still do on some occassions. It's pretty fun to fly. It's very different from a traditional 5" freestyle or race rig. So far, I've only crashed on soft ground. I don't think will do well on concrete.. Arms are damn thin.. It's more or less the same betafpv's sub250g 5inch x-knight or racer x et5. But I think, these newer frames might be more durable. I don't really know. I don't dare crashing it on any solid surface. So far, it only crashed on soil and tree branches.

Ivokal   Mar 04, 2020  

I've build nearly the same quad with 1507 Motors, flying it with triblades.
Have to post my build here.
Do you have tried to fly bigger 3s batteries to archive longer flight times? I maybe want to try out 1400-1600 mah, to get around 8-10 minutes. And want to try biblades, are the kingkongs working well for you?

freerider101   Mar 14, 2020 

Hey Sorry for the late reply. I haven't been flying or building lately. The world is just goig to chaos. :( Yes, I tried it with a 1550mAH 3s lipo. I get around 8minsish.. THe problem with these motoros is they can't hanlde heavy weight. It flies like a mountaineer with super massive backback going up everest. I would also need to be careful with throttle as going full throttle draws a huge amount of current and sags the voltage. It takes a while for the voltage to recover. Other than that, it can fly. It losses it's reactiveness and punch but you do gain flight time. 850mAH is the best balance of flight time and manuverability. ~ 5mins..

freerider101   Mar 14, 2020 

For cruising and long range, I'm considering building a 3S lithium ion pack. It would probably just as heavy as a 1550mAH 3s but imagine a having 3000mAH! :D For now my building is on hold, I can't really order anything until this corona thing subsides. :(

newtrojan   Dec 11, 2019  

I am wondering if this could be converted to a DJI system

freerider101   Mar 14, 2020 

It's possible but tight. But it should work out with taller standoffs.

Elesar   Nov 07, 2019  

nice work!, i would try also airymotors 1306...should be ligher and more efficient bit maybe bi blade 5inch is too mich as they are well tuned for 4". Check the moby 4

Nightprowler   Oct 27, 2019  

Welcome in the ultralight Druckbär-family

freerider101   Oct 27, 2019 

Thanks. :) I'm actually looking into building a 5 or 6inch long range with a Druckbär frame but with a beefier 2207 or bigger motor. I can really see that weight helps a lot with efficieny. These ultralights react like speed-demons and flies like feather. I'm really mindblown. :)

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