Wattflyer RC Network: RC Universe :: RCU Magazine :: RCU Forums :: RCU Classifieds :: RCU User Reviews :: RCU YouTube
Home Who's Online Calendar Today's Posts RealTime Post Spy Mark Forums Read
Go Back   WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > General Electric Discussions
Register Members List Wattflyer Extras Articles Search Today's Posts Mark Forums Read Social Groups

General Electric Discussions Talk about topics related to e-powered RC flying

Thank you for your support (hide ads)
Reply
 
Thread Tools Display Modes
Old 12-30-2016, 04:41 PM   #1
tkametz
New Member
 
Join Date: Dec 2016
Location: Scotsdale AZ
Posts: 4
Thanked 0 Times in 0 Posts
Club: Sun Valley Flyers
iTrader: (0)
Friends: (0)
Default How do I choose a servo?

I'm building a Super Sportster 60 that I am converting to electric. It has a 60" wingspan and will weigh 6 - 7 lbs. What size servos should I use?

Tom
tkametz is offline  
  Reply With Quote
Old 12-30-2016, 06:53 PM   #2
dahawk
Super Contributor
 
dahawk's Avatar
 
Join Date: Jul 2011
Location: Keller, TX
Posts: 4,880
View dahawk's Gallery6
Thanked 281 Times in 275 Posts
Club: 114th RC Aero Squadron
iTrader: (0)
Friends: (21)
Default

Standard size. Lots of choices in terms of torque, digital versus analog, cost, etc.

I'd check with Hitec, Savon and Futaba for the higher end.

You can spend $8.00 each or $80.00 each. I've used several different brands. Pick your poison but on such a nice model, I'd go for quality.

Check Tower hobby, headsuprc, HK, servo city, etc. Compare torque.

Hawk
dahawk is offline  
  Reply With Quote
Old 12-31-2016, 11:44 AM   #3
ron_van_sommeren
homo ludens modelisticus
 
ron_van_sommeren's Avatar
 
Join Date: Jul 2005
Location: near Nijmegen, Netherlands
Posts: 880
Thanked 169 Times in 148 Posts
Club: www.rmvc-cumulus.nl
iTrader: (0)
Friends: (0)
Default

Calculate the required torque of your servo
www.ecalc.ch
→ toolbox
→ control surface movement

ron_van_sommeren is offline  
  Reply With Quote
Old 12-31-2016, 01:45 PM   #4
Bald Paul
Member
 
Bald Paul's Avatar
 
Join Date: Mar 2011
Location: Boiling Springs, SC
Posts: 547
View Bald Paul's Gallery9
Thanked 35 Times in 33 Posts
Club: Campobello Flyers
iTrader: (1)
Friends: (4)
Default

One more thing to consider is the draw of the servos. I would suggest you use either a UBEC unit, or just install a receiver pack (you have the room, and the added weight isn't worth worrying about). In a model this size, don't rely on the BEC circuit of your ESC.

What goes up, must come down. The trick is to keep it in one piece.
Bald Paul is offline  
  Reply With Quote
Old 12-31-2016, 02:17 PM   #5
ron_van_sommeren
homo ludens modelisticus
 
ron_van_sommeren's Avatar
 
Join Date: Jul 2005
Location: near Nijmegen, Netherlands
Posts: 880
Thanked 169 Times in 148 Posts
Club: www.rmvc-cumulus.nl
iTrader: (0)
Friends: (0)
Default

+1 Paul
But don't use Eneloops or similar NiMH. They hold their charge good over time, a bit too good for servo's, not high current. Excellent for Tx though.

SBEC = UBEC
I prefer the SBEC acronym because the S gives information: switching, as oposed to linear (just BEC).
UBEC (universal) was/is a SBEC make.


The higher the power-pack voltage, the fewer servo's a non-switching = linear BEC can handle. Switching BEC's don't have this restriction.

Battery voltage?
The higher the battery voltage, the hotter a linear BEC will get, for a given current/load/servos.
Or, in other words ...
The higher the battery voltage, the lower the current a linear BEC can supply. In depth:

ron_van_sommeren is offline  
  Reply With Quote
Old 01-01-2017, 04:01 AM   #6
FoxProGT
Member
 
Join Date: Dec 2015
Location: Troy Michigan
Posts: 87
Thanked 0 Times in 0 Posts
iTrader: (0)
Friends: (0)
Default

I too am in the search for the right servos. All my research is pointing me in the analog direction. Im starting to feel that digital servos wouldn't put me at ease while flying. Id give up smoother servo movement for less amp strain on the bec.
FoxProGT is offline  
  Reply With Quote
Old 01-03-2017, 09:47 PM   #7
Xpress..
Team Hitec, CSR
 
Xpress..'s Avatar
 
Join Date: Jul 2008
Location: San Diego, California
Posts: 168
Thanked 11 Times in 11 Posts
Club: Alpine Aero Squadron
Awards Showcase

3kW 
iTrader: (0)
Friends: (2)
Default

Originally Posted by FoxProGT View Post
I too am in the search for the right servos. All my research is pointing me in the analog direction. Im starting to feel that digital servos wouldn't put me at ease while flying. Id give up smoother servo movement for less amp strain on the bec.
Generally speaking, the same size digital servo won't tax a BEC much more than an analog servo. For example, the Hitec HS-645MG and the HS-5645MG have identical current draw specs, the only difference between the two is one is analog and the other digital. If you want to get down to the technical details, the digital servo may be drawing just milliamps more than the analog servo due to its constant re-centering, it's not enough to be concerned over.

I am using 4 HS-7954SH's on my 70" Aerobeez Slick powered by a Castle 20 amp BEC Pro set to 8.0V, the BEC doesn't get warmer than the ambient air temperature. There's plenty of BEC choices out there to power your servos depending on the load. Some of my real good friends are using the same BEC PRO unit on their 35% gasoline airplanes with 8 high torque high powered digital servos and don't have any issues. They run the BEC PRO on 3S to give the servos a constant feel. On bigger airplanes, I generally won't use an integrated BEC on an ESC.

For the OP, I'd recommend the HS-5645MG if you want a digital servo or the HS-645MG if you want an analog servo.

Team Hitec, Customer Service Representative
Team Aerobeez Pilot
Xpress.. is offline  
  Reply With Quote
Old 01-04-2017, 11:19 AM   #8
FoxProGT
Member
 
Join Date: Dec 2015
Location: Troy Michigan
Posts: 87
Thanked 0 Times in 0 Posts
iTrader: (0)
Friends: (0)
Default

Originally Posted by Xpress.. View Post
Generally speaking, the same size digital servo won't tax a BEC much more than an analog servo. For example, the Hitec HS-645MG and the HS-5645MG have identical current draw specs, the only difference between the two is one is analog and the other digital. If you want to get down to the technical details, the digital servo may be drawing just milliamps more than the analog servo due to its constant re-centering, it's not enough to be concerned over.

Yeah im alittle paranoid on the matter.
FoxProGT is offline  
  Reply With Quote
Reply

  WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > General Electric Discussions


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
The Extreme Flight Edge 540T-EXP ARF-48 x-nitro 3D Flying 16 02-25-2016 02:58 PM
Very Strange Servo Interaction kyleservicetech RC Radios, Transmitters, Receivers, Servos, gyros 10 12-02-2014 07:48 AM
old airtronics servos? k-vette RC Radios, Transmitters, Receivers, Servos, gyros 9 02-06-2012 01:13 PM
3S or 4S Battery Question(s) RCFlyer44 Power Systems 22 03-29-2011 04:55 AM
servo zero, angle of the dangle, and flight surface equal travel DanWard Beginners 4 02-10-2011 04:57 AM


All times are GMT +1. The time now is 12:51 AM.


Powered by: vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

Charities we support Select: Yorkie Rescue  ::  Crohn's & Colitis Foundation



Page generated in 0.09197 seconds with 36 queries