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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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
I would usually just suggest throwing battery at the problem, but at 1700KV, a 5S 2200mAh pack is probably enough to saturate the stator and push the props to the limit, so that wouldn't be it.
I think the BH motors would get you a marginal improvement, but it's more about the weight than any other change. I still feel like 1500KV is really the target because that opens up 6S setups for going really fast, which is enough to push the props to the distortion limit.
I'd say finish the build with Eco2's, see what pace you really end up with, and what props it likes (HQ 7x4x3 is most likely to be best, but the DAL 7056C PRO - must be the latest pro - are actually good for fast cruising, and GF7040Tri are also pretty good, but all of those options are limited at extreme top end power, getting above 200kph is a real stretch just because of the props, and being lighter weight is really how to address that... but there aren't many applications where holding sustained 175kph isn't adequate.
Thank you for your detailed reply!
I just came from 2207 1800kv Xing and they wre handling the 6" tri pretty well on 5S, but of course I have missed the torque there.
I have seen the great and "dynamic" video by Furadi (cant paste link so keyword "Emax 2807 1700kv")
Where he is flying with the same motor (1700kv on 6S on tri 7") and this bought me... :)
But the the nearly 40g weight saving / 4 motors and the huge 12x6x4 bearings of the BH motors + their famous quality are also sounds tempting.
(I'm thinking about picking the higher kv version, because the 1920kv with 6" on 5S also sounds like a dragster to me, the responseness and quick throttle handling must be great. - I like pushing the limits...in the prehistoric days I was using the Emax 2206 1900kv with biprops 7" on 4S :D and suprisingly those motors were performing very well.)
It's more KV than you need already, Conrad isn't spending much time at wide open throttle, realistically the 1700KV is just extra ability to pull amperage if you need it out of a crazy dive, the rest of the time it's not helpful.
I'd finish the build with the parts you have, see how well it flies for you and the batteries you have, play around with the cheap and easy to change parts (props, batteries) as well as settings (throttle limits, base tunes) and then consider throwing another $80 towards the problem in the form of motors.
If you want outright speed, 2808 is likely the better option (also BrotherHobby) and in the similar price range (actually cheaper if there's a Mid-Range Mountain Surfing group buy happening). If you want the control precision, 3106.5 motors (Kabab - again BH manufactured) are actually slightly nicer for that. There are more options to consider, but I'd suggest running what you have to see which is worth pursuing
Thank you for your reply! You pull me back to the racionality... :)
I have fallen victim to the dangers of having four extra motors sitting around wanting to turn into another quad.
Hehe I can feel your "pain" :)
I have already 4pcs 3BR 2408 1900kv PRO II, brand new...somehow I do not trust that brand and that motors...
(and I have 2 pcs Emax 2807 as spare)
Use those 3Bh Motors!!! For a Floss 7" build, they are absolutely perfect, they've been incredibly solid for me, honestly until the Eco2's came out those were my favorite $15 motor.
Do you mean the "3BHOBBY Racing Motor 2408 PROII KV1900" ?
I have these (the purple/black version, 29 USD (each) on the BG.
I have the older 'training' ones (see quad on the left) that aren't that nice, and I've sent that thing hard. Works better on biblades, or with 6" props because they're a pain to tune, but those are seriously nice motors, use them.
Thanks bro for the advices!
Happy flying! :)
Hey!
So I'm running the BH Avenger 2806.5 1700kv on a chimera 7 running 6s packs, I've been testing with 7" props trying to see what gets me the highest top end, and I seem to be maxing out at about 140kmphb (tested with 2200mah 6s) in a straight line, and upto 160kmph in a slight dive.
But if I'm reading this correctly, would I be better off running a 7" bi blade, or a 6" tri, with a 5s pack?
Rather than 7" on 6s?
Also, in my experience with tri vs bi on a flywoo explorer, tri seems to give better stability, while bi seems better on efficiency, does that track into the big prop domain? And do you find that the overall larger prop size means any loss of stability on bi blades is less noticeable than on a smaller quad?
Oh also, that top speed was on the HQ 7x4x3, I got about the same on a 7x5x3, but it didn't feel as nice to fly.
Heyho,
Thanks for your kind and detailed reply.
I have found this HQ props
https://www.racedayquads.com/products/hq-prop-6x4-5x3-tri-blade-6-prop-4-pack-gray
which seems to be promising, as kind of bullnose, so I hope with a high enough RPM it would provide the power and top speed you need.
Test flight with this will be on this week, I will get back with the result. I pland to test with 5S and 6S.
Cheerz,
B
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.
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?
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)