Finwing Sabre FPV/UAV Elite___ Support / Build / Discussion - Page 35 - RC Groups
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May 15, 2017, 05:01 PM
Live Free and Fly
Quote:
Originally Posted by moti007
with 2X5200 4S its 85mm with pantilt and fpv camera and HDruncam
Thanks. I'm running a large Cobra motor and 12g servos in the tail so that's probably where the extra weight is coming from. I can't get it to balance at 85mm unless I move the 2x 5200 4S into the nose. Maybe it's time to get a 16,000mAh battery.
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May 20, 2017, 04:51 PM
Registered User
Yes 16 is the best...
May 20, 2017, 05:38 PM
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Took the maiden flight today. I believe the factory CG of ~85mm is a bit off. I think after seeing how it flew on my 35+ minute flight I will play around with the CG. It looked a bit tail heavy when balancing on the ground, but flew like it was a bit nose heavy, always requiring a bit of up elevator. I will run some calculations, take another test flight and report.

Other than that, it flew beautifully. Although there was a bit of blustery wind up there, it really didn't affect it at all. Just shrugged it off and was very stable.
May 20, 2017, 11:38 PM
Live Free and Fly

Factory CG wrong?


I took the time to input the Sabre specs (as good as I could measure them) into the eCalc CG calculator and it came up with the correct CG around 10mm further away from the wing LE. If anyone wants to do the same to verify my results, feel free.

For my maiden flight I balanced it on the factory CG of ~85mm and on the ground it looked tail heavy but flew definitely nose heavy. Now I know why.

Here's the link to the Sabre calculations I came up with.
May 21, 2017, 01:59 AM
Registered User
Thanks bmw111 ,
You fly with thus cg?
May 21, 2017, 10:12 AM
Live Free and Fly
Quote:
Originally Posted by moti007
Thanks bmw111 ,
You fly with thus cg?
Not yet. I will report on my results with the new CG after my next flight.
Jun 04, 2017, 06:07 PM
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Revised CG


I've flown two flights with revised CG, one at 95 mm from wing leading edge, and the second flight at 97 mm from wing leading edge. With my plane's current setup, 97 mm performs best. I have a Yi action camera with BEC and 1100mAh 3S battery in the nose, Mobius and flight camera on a ProPan at the pan servo mounting point, and running two 5200mAh 4S MultiStar batteries.

I have a 16000mAh MultiStar on order, when I install that I will probably remove the Yi action camera/BEC/battery. That will take out quite a bit of weight from the nose, so I may have to adjust CG again. But as of right now, it flies great at 97 mm from the wing leading edge. And when I say "great," I mean no mechanical elevator trim, flying straight and level at 50% throttle.
Jun 04, 2017, 07:04 PM
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smoothvirus's Avatar
Quote:
Originally Posted by bmw111
I have a 16000mAh MultiStar on order, when I install that I will probably remove the Yi action camera/BEC/battery. That will take out quite a bit of weight from the nose, so I may have to adjust CG again. But as of right now, it flies great at 97 mm from the wing leading edge. And when I say "great," I mean no mechanical elevator trim, flying straight and level at 50% throttle.
I have done some test flights with a 16000mAh 4s MultiStar installed in mine, it flies fine. It's a little heavy and the climb out is more shallow but it handles OK.
Jun 05, 2017, 05:06 AM
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someone use the landing gear?
Jul 11, 2017, 12:04 PM
Registered User
Since it was my first plane she went together well, its up and flying! Wish I would of got the whole package with the landing gear and FPV mounts. Working on a "Take off switch" for mine (Throttle and some up elevator), But she fly's good had a few bad launch attempts and busted the bottom nose module but its foam tac'd and taped on! Using two 5200's in the nose with some more weight added to get the correct CG.
Jul 11, 2017, 05:28 PM
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smoothvirus's Avatar
Quote:
Originally Posted by deepflight
Since it was my first plane she went together well, its up and flying! Wish I would of got the whole package with the landing gear and FPV mounts. Working on a "Take off switch" for mine (Throttle and some up elevator), But she fly's good had a few bad launch attempts and busted the bottom nose module but its foam tac'd and taped on! Using two 5200's in the nose with some more weight added to get the correct CG.
I came to the conclusion that the landing gear probably isn't worth it. Sabre is better off as a belly lander.
Jul 12, 2017, 01:59 AM
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It's my birthday gift


Well I now know what my girlfriend is getting me for my birthday
Jul 12, 2017, 11:05 AM
Extreme Superlative Hyper-Pro
Moto Moto's Avatar
The stock landing gear failed on the first landing for me. Both the main and nose are too fragile for an 8-lb airplane.

I've refitted with parts from the LHS. The alloy main gear was flattened to lower the profile. The 5/32" nose gear was rebent to shorten and align the wheel with the steering shaft. It has 1/4" nylon pipe nipples from Lowe's cut down for bushings, inserted from top and bottom and they fit perfectly.
Jul 15, 2017, 12:31 PM
Registered User
If anyone has been interested in using LiIon battery packs, I've used one with my sabre. I used a 4s3p pack of 18650GA cells for a total of 10.5 AH with a rated 30 amp discharge.
AUW with the pack was 2.7 Kg, so this is a pretty light set up for the sabre. At full throttle there was a lot of voltage sag and the amperage peaked at 33 amps, so a 3p set up is definitely not enough, I'm about to order more cells and make a 5 or 6p pack for an AUW of around 3.1 to 3.3 Kg.
All of these AUWs are with a bare bones pnp sabre, but I think they are still very low considering that it is with a 4s 10 to 20 AH battery.
Jul 15, 2017, 07:37 PM
Live Free and Fly
There has been a lot of discussion in the Mini Talon thread on Li-ion packs in comparison specifically to Multistar 4S 10C packs and the consensus seems to be that the Li-ion packs are only preferred in a very narrow use profile, such as very long range and limited throttle application, among other limitations.


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