Interesting viewing if you are considering a 7"
another guys approach…
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Good. I think I may go for 12 molicel p42a 21700 li-ions for a 6s2p pack. Max draw can go up to 60-90amps then? Should weigh less than 400g as opposed to my lipo at over 600g.
Also, considering a second vas crosshair extreme patch so I can do this to my goggles
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That makes excellent sense, would be great to see what range you get with that 
but how would you package them, at a push you could get 2 long 3 wide 2 high, my new GPS mast limits me to 2 long at 18650’s 
Shout me down if I’m talking bollocks, but with diversity is it not better to have two different antenna constructions for different signal paths/polarisations ??
2 rows of 6. Pretty sure they’ll fit. I’ll check.
I’ll be using diversity or fusion. I figure this way I’ll have a good coverage straight in front with a coverage angle of more than 180 degrees horizontal. But I’m not an expert, just what I’ve seen on youtube.
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21mm x 70mm. I have space for 150mm long and 40-50mm wide.
If I stand them up, I can get 2 rows of 6 no problem. The pack would be 126x42mm roughly.
Maybe I could go for a bigger cell 
Or lay them flat. That would be about 150mm long, 63mm high, 42mm wide. That might be better…
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With my GPS mast I’m limited to 142mm long, but I could always move it back, the joys of 3D printing
I’ve bought my 18650 cells so I’ll try those first. see what they give me. How many laps of the flying field it can do in ‘mission’ mode 
My opinion for yours FWIW would be …
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Here’s the parts list.
(link to Excel spreadsheet for the purchasing links to work)
Parts list 200124.xlsx (15.5 KB)
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Whilst I still intend for the main batteries on this craft to be LiIon I’ve got this 2600 4S pack from GMB for first flights whilst I assess the current draw. It’s a more suitable size for first flights than the 5200mAH shown in the last build video.
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Being unable to fly, I have been doing the odd hover test whilst changing settings in Betaflight.
I can hover for around 16 mins on a 6s 4000mah lipo, so I reckon I can get a good 10 mins (~8 miles) flying time in. The better the tune, the more efficient and smooth the flights will be.
I have been adjusting the PD gain mainly. As it is a bigger craft than the usual Betaflight 5" quads, you need higher PD. I’ve used a preset from the below website. The guy is pretty meticulous on tuning using the blackbox logs.
You basically fly a few manouvers / flips etc and analyse the saved blackbox file with spectral analysis, pid errors and filter effectiveness etc 
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I’ve also been spending some time reading up on PIDs and looking through blackbox logs over teh past week or so. I’d not come across that site though - looks good - I’ll take a look, ta!
edit: ah! I saw him mentioned in a Josh Bardwell video, apparently the guru of PID tuning. Cool!
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Great Video very informative 
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Upgraded the tail to fit the 6s balance lead to stop it flapping about.
The tail now has an immortal T mount (rx antenna), a bolted pigtail mount for a vtx antenna, a snap in gps mount, XT60 mount and a balance lead mount for a battery up to 6s.
All at 30 degrees (my flying angle, the same as my cameras) except the balance mount.
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Thank you, appreciated 
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Nice one Karl
How do you secure the XT60 in place? they usually need a good tug to disconnect them
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Um. I’ve used some E6000 adhesive 
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Good stuff, I use it a lot
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7" running on 18650’s 6S2P
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