New Tail Servo

[stargazer]

I need a new tail servo for my Trex 550 v3 dfc,I found this a RJX HV Fso521thv which looks good specs for the price.Problem is the voltage rating for it is 7.4 to 8.4volts and as I will still be running Align 615s on cyclic that require 6volts I wondered if its possible to run the tail servo at a higher voltage than the cyclic servos or if anyone had safely run the Align 615 at 7.4 volts.

Cheers Dave.

[TheDarkPassenger]

This one?
RJX FS-0521HV Metal Gear Digital Servo Ultra High Speed and Torque 21.3kg / 0.05sec / 68g

In the specs it suggests it would move pretty rapidly @ 6V so you should be able to run it happily on the same voltage as the cyclics.

[stargazer]

Would be a good solution but at 6volts would'nt the speed of 0.07 be slow compared with most modern day tail servos,should have good holding power with that amount of torque though.

[TheDarkPassenger]

I'd imagine there will be limited difference, however the 'real' difference in feel between 0.07 and 0.05 I couldn't answer, sorry..

[waveydavey]

I think you'd be hard pushed to see the difference, I used DS620's for a few years on my 600 which is 0.07 at 6.0v and I can't tell the difference between that and a 650 which is 0.05 they're both for 60 degrees so for normal movements you're talking milliseconds. Maybe some could tell the difference but I think most of us wouldn't notice. The hold will be more locked in with the faster servo but again a couple of years ago you were talking a good tail servo at 0.1 to 0.12 and that was considered okay(at the time)

[philipjdall]

Why not go for a secondhand BLS251, which is one of the best tail servos? specs say it won't run at 6v but it'll actually work beautifully. Far better than the rjx option and lighter too.

http://www.rcheliaddict.co.uk/sale/1...50-posted.html

[dj propo]

Why not go for a secondhand BLS251, which is one of the best tail servos? specs say it won't run at 6v but it'll actually work beautifully. Far better than the rjx option and lighter too.

http://www.rcheliaddict.co.uk/sale/1...50-posted.html

really.. is the bls251 defo ok @ 6v, was thinking of selling one of mine but will keep it if its absolutely no problem.

[philipjdall]

Yes, it's absolutely fine at 6v. I have four helis with exactly this setup (some of them been running for years) and never had a problem.

If you think about it, the 4.8v specification comes from a four cell nimh pack (1.2v x4). Fully charged these packs kick out 6v so the servo is more than capable than handling it.

I wouldn't go above 6v though (although some have, with success).

[trillian]

This one?
RJX FS-0521HV Metal Gear Digital Servo Ultra High Speed and Torque 21.3kg / 0.05sec / 68g

In the specs it suggests it would move pretty rapidly @ 6V so you should be able to run it happily on the same voltage as the cyclics.

That's not really intended to be a tail servo as far as I am aware. I have three of them on the swash of a heli but have a Futaba tail servo.

Tail servos don't need anywhere near as much torque but they must be capable of sustained constant and fast movement.

[philipjdall]

That's not really intended to be a tail servo as far as I am aware.

Trillian you're right, it isn't a tail servo – but in this instance i actually have used one of them as a tail servo for a few months and didn't give any problems. I can't comment on it's longevity though is it was only on the heli for about two months.

In my opinion the OP would be better off with staying with his BLS 251

p

[trillian]

Trillian you're right, it isn't a tail servo – but in this instance i actually have used one of them as a tail servo for a few months and didn't give any problems. I can't comment on it's longevity though is it was only on the heli for about two months.

In my opinion the OP would be better off with staying with his BLS 251

p

Yeah it makes me wonder exactly what the differences are these days between a dedicated tail servo and fast swash servos that are used in a FBL setup. I know most of the tail servos now are running at 760 instead of 1520 pulsewidth but I remember hearing once that the whole 760 thing wasn't any big advantage .

I will add though, that I am running those RJX servos at 5.6 volts from a Kosmik BEC. I also ran them direct off a 2s LiPo but they do the job perfectly fine at 5.6 volts and it makes it all much simpler (and yeah I know the BEC can be set to output more volts but I don't have a prog disc and it's working great as is).