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Old 12-03-2018, 10:45 PM
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Totally agree Cam. As long as you build the ailerons with twist strength in mind, and you take machanical advantage when you setup the servo, one servo would definitely work!

A couple unlimited pilots I’ve seen are experimenting with shortie ailerons/one servo... and they seem to fly just fine!

-Craig
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Old 12-04-2018, 12:30 AM
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My question is, is saving 5 oz worth losing the added redundancy of having 2 servos? Sure there is cost savings, but when you are talking about 400.00 against the total cost of the airplane... You can argue that it simplifies setup as well, but I have never found this to be a big issue either.
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Old 12-04-2018, 12:39 AM
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Quote:
Originally Posted by orthobird View Post

I wonder what the torque would be at 8.0 volts? And was it not tested there? Which is the voltage of a fully charged 2S lipo battery

anyone have any data / experience / info???
Futaba traditionally use 4.8, 6.0 and 7.4 volts as their stated specs for servos. This is based on 4-cell NiCAD/NiMH, 5-cell NiCAD/NiMH, and 2S Lion/Lipo.

You can extrapolate between those various points.
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Old 12-04-2018, 07:17 AM
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it depends on the servo model, some may get fried at 8.4V (don't support over 7.4V)
in this case Futaba does not reccomend the use of a voltage regulator so it must be fine.
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Old 12-04-2018, 08:48 AM
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If it says "7.4v" they really mean 8.4v since that is a fully charged 2S lipo. If it gets fried at 8.4V, I have no use for it.
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Old 12-04-2018, 09:45 AM
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A 7.4 volt rated Futaba servo in intended for use with 2S lipos. A fully charged 2S pack will not fry it.

However, a servo rated for 4.8 volts will likely not work for very long at 8.4 volts. Having said that, I have used the 3150 glider wing servo, rated for 4.8 volts with fully charged 2S LiFePO4 packs.
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Old 12-04-2018, 11:43 PM
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Futaba claims that these HPS servos are twice as energy efficient as the old BLS servos. I assume that an entire line of HPS servos will be developed. Not all of them have 1000 in-oz. There is a F3C servo with a mere 250 or so. The videos indicate that the servo performance is much better as regards overshoot and sludge into position. So apparently a new brushless motor and controller logic as well as a new control loop ? See RC Japan listings.
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Old 12-05-2018, 08:35 AM
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There is four servos in the new HPS line. Two for helicopter, one listed as surface CB700 and the A700 of 1000 + oz.
None are listed as F3C - but small and large heli.

Of interest for GS is the CB700 at 700 oz with a speed of .06 and of course the 1024 oz A700.

Got both A700 and CB700 - but will have to wait untill spring to use them - cold and snow here.
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Old 12-05-2018, 10:02 AM
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Send them to me!!! I will test it
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Old 12-05-2018, 10:15 AM
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Well according to RC Japan:

https://www.rcjapan.net/index.php?ma...2j3kqet0nlmdb7
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Old 12-05-2018, 11:02 AM
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Quote:
Originally Posted by ghoffman View Post
If it says "7.4v" they really mean 8.4v since that is a fully charged 2S lipo.
as I said above it depends on the servo model.
if so what's the maximum voltage for a 8.4V rated servo ?
why does Futaba not show its numbers at 8.4V if it really supports it ? (marketing wise)

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Old 12-05-2018, 11:12 AM
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I did not mean to say there is no performance difference between 7.4 and 8.4V, but that anyone that claims HV/7.4v is good for 8.4V.
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Old 12-05-2018, 11:23 AM
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I wouldn't think they would provide torque and speed data for 8.4 volts since that is a peak voltage only and doesn't normally last long. 7.4 Volts is the nominal voltage that you would expect from a 2S LiPo battery. The 7.4 Volts performance is something you can depend on throughout the flight.
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Old 12-05-2018, 11:31 AM
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Good point Steve

But.....

I got me a bird with CB 400 and I use 3S, I set the voltage output to 8.1

That way, flight after flight, my servos see a constant 8.1 volts from one charge
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Old 12-05-2018, 12:11 PM
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Quote:
Originally Posted by Flybye Steve View Post
I wouldn't think they would provide torque and speed data for 8.4 volts since that is a peak voltage only and doesn't normally last long. 7.4 Volts is the nominal voltage that you would expect from a 2S LiPo battery. The 7.4 Volts performance is something you can depend on throughout the flight.
There is a growing trend with using 3S batteries with a regulator above 8.0V.
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