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HelicopterMain Discussion › 7.4V system - is it safe?
07-13-2008 10:15 PM  9 years agoPost 21
AirWolfRC

rrProfessor

42½ N, 83½ W

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I have been running Hitec HS81's on throttle at 8 volts for over 1 year now with 0 issues.
Hmmmm . . . . I think I like that.

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07-13-2008 11:25 PM  9 years agoPost 22
Climax

rrVeteran

West London, United Kingdom

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Take a look at the top of page 2 of the JR UK importer's newsletter...

http://www.macgregor.co.uk/newslett...er_0608_web.pdf

Here JR is effectively saying that they do seem to work in this configuration, but they won't cover it as such under their warranty.

In Europe the 8717 is called the 8915 just to be confusing!

I'm planning to use these in my Trex 700 build, but will power them from an unregulated A123 Systems pack just to be on the safe side - as in fact has already been suggested.

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07-13-2008 11:44 PM  9 years agoPost 23
RCMed-x

rrVeteran

westpalmbeachflorida usa

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Mike F flew my Raptor 50 this week with all 8717s that have been beat for over 6 months and they still feel new .
4 8717's
TJ rev max
VR5203 reg
GY611 gyro regulated
No issues

A good teacher is a good listening student !

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07-13-2008 11:58 PM  9 years agoPost 24
AirWolfRC

rrProfessor

42½ N, 83½ W

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Ok, - - -

The old s9253 tail servo is 27 in oz at 0.08 sec & 4.8V
The s9254 tail servo is 47 in oz at 0.06 sec & 4.8V
The HS-81 is 42 in oz @ 0.09 sec & 6V

Aside from the faster pulse rate for the s9253/4,
- - How would the HS-81 work on the tail ?

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07-14-2008 12:04 AM  9 years agoPost 25
Mike Fortin

rrElite Veteran

USA

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The HS81 is a mini servo, I would not recommend it on the tail as precision is needed for tail as well as a faster frame rate.

Have Rotors, Will Fly!

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07-14-2008 12:11 AM  9 years agoPost 26
AirWolfRC

rrProfessor

42½ N, 83½ W

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Yes, I cited the frame rate difference and most gyros will accomodate standard frame-rate servos.

My question remains, will an HS-81 be "good enough" for something like a 50 ?

Especially after you add "chinese weights" to the tail ?

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07-14-2008 12:20 AM  9 years agoPost 27
Mike Fortin

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USA

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I would reccomend against it but hey, experimentation is what "Hobbies" are all about.

Have Rotors, Will Fly!

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07-14-2008 12:22 AM  9 years agoPost 28
AirWolfRC

rrProfessor

42½ N, 83½ W

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Precisely . . . . that's what happened with the 8717.

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07-14-2008 12:28 AM  9 years agoPost 29
PBusch

rrKey Veteran

Minnesota

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Why just the 8717 and not others?

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07-14-2008 12:52 AM  9 years agoPost 30
Yug

rrMaster

UK. Herts

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Is there a difference bewteen the DS8717 and the JR8717 ?

Vegetable rights and Peace

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07-14-2008 12:55 AM  9 years agoPost 31
JAGNZ

rrProfessor

Auckland, New Zealand

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Why just the 8717 and not others?
Because the Pro's proved the 8717's were up to the task at 8v. No other servo has been tested in this way. But feel free to try it out and report back.


Jason Greenwood

www.3dheli.co.nz

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07-14-2008 01:06 AM  9 years agoPost 32
Yug

rrMaster

UK. Herts

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I'm just a bit puzzled at the variants. Been using 8715s which I understood were mechanically and electrically similar to the 8717except for the heatsink but then there appear to be 2 or more variants of the 8717 so I'm confused and would like clarification. As is often the case, different part numbers are introduced for the exact same product, but these need to be verified as to being the same thing.

Vegetable rights and Peace

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07-14-2008 01:21 AM  9 years agoPost 33
Wingman77

rrProfessor

Pulaski Tennessee

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the ds8717 is JR I believe that just means digital servo

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07-14-2008 02:02 AM  9 years agoPost 34
PBusch

rrKey Veteran

Minnesota

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Because the Pro's proved the 8717's were up to the task at 8v. No other servo has been tested in this way. But feel free to try it out and report back
Thats just it, you could probably run most servo's at 8v. If their like anything else there's a bit of headroom in the specs put their for longevity.

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07-14-2008 08:11 PM  9 years agoPost 35
2DMAX

rrNovice

Clwyd, UK

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Gulp!!! is that a 2.0A draw on each?

I just do standard flying at present. Bought 3 x DS8715's just for speed on 4.8v a while back (not thinking about current draw). Using a 2400mah RX nicad plus DS811 throttle , 8900 on tail, I put back only 630ma after 2 flights (i'm using Futaba 2.4GHz in a Trex 600 pro). Have been looking at a Scott Gray Reactor X to run them on 6V, because i was starting to worry about current draw, but wasn't sure they would handle 6V comfortably.
Looks like I should get one before I do anything with a harder pull on the servos? .

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07-14-2008 08:20 PM  9 years agoPost 36
Wingman77

rrProfessor

Pulaski Tennessee

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they will only pull that much current under a heavy load. and if you go to 6v they should pull less current with the same loading

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07-14-2008 08:29 PM  9 years agoPost 37
AirWolfRC

rrProfessor

42½ N, 83½ W

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Any motor will pull MORE load with more voltage for the same load.
It will pull the higher load for a shorter period of time, however.

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07-14-2008 09:01 PM  9 years agoPost 38
2DMAX

rrNovice

Clwyd, UK

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So the DS8715's should run easily on 6volts, and the life of the servo should be a lot longer than a servo running on 7.4/8 volts , and not worry about the 4.8volt limit set by JR.

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07-14-2008 09:11 PM  9 years agoPost 39
AirWolfRC

rrProfessor

42½ N, 83½ W

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If the spec says 4.8V then 6V would not be a good idea.
There's nothing that says the 8715 is built like the 8717.

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07-14-2008 09:29 PM  9 years agoPost 40
2DMAX

rrNovice

Clwyd, UK

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OK! Thanks alot AirWolfRC. When Yug said he understood the 8715's were electrically and mechanically similar to 8717's, I started to worry a bit about using it with a 2400mah nicad pack.
I've been a bit of a battery worrier, that's why i've stuck with nicads for so long. (I've been happy with them).

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HelicopterMain Discussion › 7.4V system - is it safe?
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