Long Range Lightning Bug

By Ewiley on Sep 01, 2021

5  195  0

Finally decided to jump on the light-weight LR bandwagon with the Flywoo LR4 frame, a Caddx Polar Vista, and some spare parts I had lying around.
This was a much more difficult build than I'd expected at first, the body is narrow and cramped, the motor wiring is very asymmetric, and there are a lot of components to cram into this little rig. Laying out everything multiple times to check clearance and fit took a lot of extra time but was worth it for a pretty good final product. This thing is a blast to fly around large open spaces at all hours of the day and with a conservative tune, feels like you're literally a soaring bird...

Thoughts on the LR4

This 'dead cat' frame is a little different than I was picturing
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(no cats were harmed in the making of this drone)

No, wait that's the wrong dead cat, here it is:
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  • I like the thick arms, but the body plates make me nervous, especially the aft stack
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    I appreciate the 16 and 20mm options, but drilling both holes here makes the 1mm carbon that much more prone to break. Ideally there shouldn't be many instances where there's a direct impact to this area, but still this seems like an oversight in an otherwise well-designed frame. Also the lack of 25mm AIO options seems like a miss on this frame.

  • There is just under 35mm front-to-back in the front stack mount between the standoffs. The 4-in-1 ESC I had lying around was just slightly too big to fit
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    Does not fit!

  • I initially thought about swapping the Vista to the front and mounting the flight stack in the rear, but then the fancy long antenna does not reach the Vista from there.
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    Nope does not work :(

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    Since I'm re-using motors I had from another project (Xing x1404 3600kv camos, baby), the wires were way too short. I happened to have these nifty LED racewires which I mounted top in the rear and bottom in the front, just to make the little guy more visible.

  • Alt TagSince I wanted to stick with 20x20, the Spedix IC25 was the only readily available >20A ESC I could find that was small enough to fit. Despite being BLHELI_S it's a pretty solid performer from what I can see. The fit was a bit tight so I opted for a sideways install, which I think works better for routing the xt30 connector.
    Protip: make sure to wrap the standoffs in something non-conductive like electrical tape! Shorting-out an ESC is a good way to have a bad day.

  • Alt TagThe included arm spars only seem to fit if you've got 12x12 mounted motors. 9x9 motors do not fit the holes on the spars. I left them off but I'd prefer to be able to use them. Doesn't seem like a huge deal in the end though.

Antenna Mounts

For the R9 dipole antenna, I noticed that Frsky did away with the plastic center node in favor of a *cough*cheaper*cough* shrinkwrapped loose antenna. I used this to my advantage to mount the diple vertically on a forever tube with some shrink wrap. I've heard this can actually work better with the dipoles since the null RF area is now directly above and below the drone, making for better radio reception in different orientations. (Paweł Spychalski has an excellent youtube video on 900mhz long range and antenna orientation, btw).
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Looks ok to me!

Putting it all together

Ok now I think we got it sorted here
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Other thoughts

This is not a hard core freestyle or racing frame. The setup is so light and the props so big I actually had some issues descending in the wind. This little guy seems affected by wind more than any other open-prop drone I've flown, but it sure is fun to fly. Cruising around is much quieter and discrete than a 5" freestyler and the battery life is phenomenal, I get easily 7-9 minutes cruising with a 650mah 4s.



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