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servos

What servos to use in a size 60 extra 300

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Russell Cowan16/12/2014 18:22:22
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Hi everyone.

I am fairly new to the sport, well just getting back into it after many years out. I used to have a glider/trainer with a very small cox engine with an internal fuel tank. Back then I always wanted an extra 330 so at the age of 29 I have decided to buy a seagull extra 300 size 60. I realise that this is beyond my skill set so I have also brought a 4 channel Phoenix x to get back into the sport whilst I build my extra 300.

The question I have for you all is what servos do I use in it? As I need 6, I don't want to spend a fortune on digital ones with metal gears as I don't think I would notice the difference, not at my level anyway. I just want some good reliable servos that are suitable for the 60 size acrobatic plane.

I would very much appreciate everyone's advise on this.

Thanks in advance

john stones 116/12/2014 21:15:36
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10824 forum posts
1482 photos

Hiya Russell

I tend to go belt and braces with servos..but think most would go with standard ones Jr 591 Futaba 3003 etc.

John

Lee Smalley16/12/2014 21:20:16
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2125 forum posts
68 photos
2 articles

the seagull extra 300 is a great model loved mine to bits ....litterally, i had a ST61 in mine and it was a great combo, for servos i used HS485HBs all round except throttle

Prop Nut16/12/2014 22:05:21
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336 forum posts
1 photos

+1 for JR591s.

Russell Cowan16/12/2014 22:12:26
2 forum posts
Thank you for your replies. I was looking at getting the Hitec HS430BH high voltage servos as I have checked and my Rx can handle it. They state that these servos are suitable for 21-60 size planes so I am hoping that they will do the trick. I have managed to get them at just under ?9 each, which for the spec is very reasonable price.
john stones 116/12/2014 22:22:59
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10824 forum posts
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Quick servo Russell, big fan of hi tec myself yes

John

Paul Marsh16/12/2014 22:23:10
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3809 forum posts
1097 photos

JR 591's don't work with 6v. They are 4.8v only and might burn out if using a Lipo or a 5 cell NIMH.

Rule of thumb: Go for the best servos you can afford. Using cheapos is not worth it, as a member at our club lost a plane for a sake of a couple of £5 servos. Bit silly spending £300 on an airframe and engine and installing a weak link, such as a cheap switch or dodgy servo just to save some money and losing the whole lot as a result.

Not logical

For servos, Hitec 645MG, or the Htec HS430BH that Russel suggested, more than enought power and can handle high voltage.You might want a more higher power one for the rudder, as it's only 4.1kg and fine for normal stuff, but for doing knife edge, a 10KG servo is required - and don't forget to use a decent battery pack, not a low capcity or old one.

Lee Smalley17/12/2014 09:03:48
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My 591 work happily with 6v and have done for 5 years!! The hs645 is a tad overkill I use them on my jet weighing 20lbs and flying at 160mph the servos he has looked at will do, he is not buying cheap hobbyking crud is he !!
Lee Smalley17/12/2014 09:08:08
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2125 forum posts
68 photos
2 articles
Although if I remember the elevator is a single servo using split pushrods, if it is I would put something a bit more powerful in there or use a servo for each pushrod
Paul Marsh17/12/2014 18:26:08
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3809 forum posts
1097 photos

JR 591's are 4.8v only. Period. You might get away with it, maybe not. Also a RCME review model crashed a few years ago when the 591 servos burnt out when using 6v. Don't know who it was, but was here.

The manufacturer states :"With plenty of torque and ample speed, the NES591 is the perfect budget everyday servo. Supplied with mounting hardware and additional servo output arms. The NES591 can only be used at 4.8v."

http://www.macgregor.co.uk/jrpropo/NES591.htm

Basic Information

Modulation: Analog
Torque:

4.8V:

71.0 oz-in (5.11 kg-cm)
Speed:

4.8V:

0.24 sec/60°
Weight: 1.34 oz (38.0 g)
Dimensions:

Length:

1.52 in (38.6 mm)

Width:

0.75 in (19.1 mm)

Height:

1.18 in (30.0 mm)
Motor Type: ? (add)
Gear Type: Plastic
Rotation/Support: Single Bearing

Edited By Paul Marsh on 17/12/2014 18:28:18

ChrisB17/12/2014 20:02:23
1220 forum posts
34 photos

I've got the Seagull 90/120 Yak. I use Hitec 5485digis.

In reallity i'd go for Hitec standard 400 size servos, or JR 591, or Futaba 3001. A lot of people over do servos, as unless you are doing a lot of hi 'G' 3D flying or blow back flying, i.e. lots of tail slides etc, then you don't really need hi Volt, hi torque.

I've done a bench test on Hitec 645 MG servos. 4.8V and 6v. At 4.8v the servo move across the bench, at 6v it jumps across the bench. Transfer that torque to an airframe, especially a light ARTF with balsa mounting and under load, in theory the servo could rip itself loose. Its only as good as its mounting.

Id go for hitec!

CB

Lee Smalley18/12/2014 11:22:15
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2125 forum posts
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2 articles

yeah yeah Paul, i have dozens of JR 591 servos and i always use 5 cell Nimhs and never has one failed, that is not really getting away with it is it ?? just my experience

Bob Cotsford18/12/2014 15:23:26
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8146 forum posts
449 photos

just to add to Lee's comment, my 1.20 power Dragon Lady came with 591s fitted and I've been running them off unregulated 2S LiFe for a couple of years now. I wouldn't advocate doing it on a 60 powered 3D model with large surfaces but for general sport/pattern flying it works for me.

john stones 118/12/2014 16:07:03
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10824 forum posts
1482 photos

Been doing it over 10 years..no fried servos nor JR rx's, never had a glitch either dont know

John

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