SourceOne 7" Budget

By tehllama on Oct 26, 2020

9  527  17

This was the rush build that let me go film the No Coast Drift Party - although I would submit a version of this as my new budget recommendation for any new 7" user looking to have something capable of long range, cruising, and high speed chasing..

What this quad was built for:

The frame is the core of this build idea, the wonderfully cheap TBS Source One 7" frame. Deadcat if you need it works great, in this case I bought what was in stock, and put together my 35° Session camera mount and called it good. At $30 per frame, this is effectively the most budget-friendly big frame one can choose for top level performance. The absurd answer is that aside from the weight (6mm arms and robust top/midplates lead to a basically 200g frame after requisite TPU mounting for camera/antennas/stack.
In terms of Blackbox Log confirmed 'least noisy frame', this is it. I have 50 quads, and the cleanest traces I've ever seen are on this frame, despite having all the problems of 7" quads. That is an insane thing once I realize it, but it's true (I've ran these with all gyro filters disabled, narrow RPM notches, and D-Term filter slider at 1.6 - no joke. Not recommended, but it does work). It's a really good frame - full stop. The fact that it's the cheapest usable 7" frame just makes that great.

Motors came from CycloneFPV, and the BH 2806.5 1700KV are brilliant options, especially if you have a variety of batteries to use.
What I would recommend now would be the EMAX 2807 1700KV units for the same use case. As it stands now, these motors are brilliant and perform amazingly well.

Stack is a clearance special from RDQ, the Flywoo Goku 722 and TMotor F45-Pro ESC. Practically I wanted reliability, and the heat sink on the ESC is quite impressive, although I'd still trade the cost of the motors down to the cheaper ones and run the Hobbywing G3 ESC instead. The F7 FC is always a great choice, and quite practically any F7 will do brilliantly. Just don't overwrite the resource CLI tab that lets the PINIO 2 do camera selection, or you get no camera functionality.
Realistically, you can end up at similar cost with the HW G3 ESC, and HGLRC/Foxeer/Aikon F7 FC to round out the stack.

FPV Gear is another budget set of choices. The Foxeer Predator4 Micro is among my favorite cameras, as it is a PAL/NTSC camera with OSD capability, and practically the best image quality for mixed lighting conditions. While not strictly ideal for color replication or fixed lighting conditions, at golden hour these cameras are the best, and I can't see a difference between the V3/4/5's, so these were on sale when I happened to be building this quad. The VTX is a super-cheap eachine TX-805 that I picked up for $12. The antenna is now a Flywoo 110mm unit, because longer antennas are great for long range - although I have ran it with stubby units for racing tracks, because I'm the kind of idiot who puts launch mode on LR quads, and runs them through MultiGP type courses.

Props are usually the limitation for 7" setups, and it's likely to remain the case. I personally run Gemfan props on most everything, but there are some niches where I prefer running the DAL T7056C's (great for fast cruising), and on the lighter 2408 build the F7's are great low speed long flight setups... but I tend to run other options 95% of the time.
The best biblades are the HQ 7x4.5's and GF7042's - I like those better than the triblade gemfans, but you're stuck with clear for durability. The HQ 7x4x3's are the most consistent out of the box, just is a struggle for badly under-motored setups.
Practically, the HQ pairing is the most reliable, 7x4x3's for these motors are basically ideal, but the biblades on this higher KV setup allows for outright hilarity to ensue on 6S 1500mAh packs... most racecars cannot keep up with me even in high speed tracks.

Batteries are CNHL, and basically all budget decisions. This setup is remarkably usable on 4S 1300mAh packs, but this is clearly a setup that favors running 5S 2200mAh, 6S 1500-2200mAh setups. I have ran everything from 4S 850mAh packs on this up to 6S 5000mAh packs. When I say that 7" quads tend not to care about weight very much, this is what I mean - I can fly for 18 minutes on that huge brick of a battery pack, and it doesn't handle drastically differently than when I'm running a 1000mAh pack.

The version I'd actually recommend would be:

Get the TBS SourceOne 7" frame. Run the EMAX Eco2 2807 motors (1500KV for dedicated 6S, otherwise run 1700KV).
Spend on the ESC (Hobbywing G3 60A), but any F7 FC will do. Camera - run what you like, I still like the Predator and would consider that worth it. Any VTX is brilliant (this build should crush on DJI with an Air Unit also). Flywoo makes good antennas, no reason to spend more there. CNHL 6S 2200mAh batteries have been crazy cheap (as in sub-$24), which is impossible to ignore.


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bulesz   Jan 27, 2021  

Thanks for the great and detailed advices!
I have Emax ECO II 2807 1700kv and pland to fly mostly on 5S, I'm thinking hard to replace them to BH 2806.5 1700kv or 1920kv (I need that speed... :) )
plus the BH motora are 8g lighter / motor (so around ~32-35g lighter / config)
Dilemma... :)
That could be an option to finish my build and try my Emax motors in live... :D

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tehllama   Aug 14, 2023 

You can run 1700KV for high speed on those motors (I have and run a set of those like that - they'll run hot, but you can fully uncork them for a bit more pace). For adding efficiency, you'll absolutely prefer biblades to add flight time, especially if you're going comparatively fast. A lot of those things to track up to the larger domain... but realize that effective prop area is growing by a scaled term, so biblades aren't going to feel quite as 'loose' as would lighter setups where you really see a huge difference... honestly I forget sometimes when I'm running 7x4.5x2's on there as opposed to 7x4x3's.

Sam Lee   Aug 14, 2023 

Thanks a bunch for your reply!
I've got some bi blades on the way to test out.

What do you mean when you say fully uncork them?

tehllama   Aug 14, 2023 

Basically trade out battery life for marginally more speed - if you're willing to be mean to 6S packs and hammer them at 80A sustained draw, then you can really unlock the top end, but you end up in a range where PID authority starts to trail off because the props are getting dynamically unloaded and the tips are entering transonic airflow regimes, which makes it really hard to make more thrust (which is what the FC needs to do in order to keep things stable)

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