Go Back  RCU Forums > RC Airplanes > Beginners
Reload this Page >

exponential definition please,

Notices
Beginners Beginners in RC start here for help.

exponential definition please,

Old 11-04-2007, 07:28 PM
  #1  
JDV500
Senior Member
Thread Starter
 
JDV500's Avatar
 
Join Date: Oct 2007
Location: Huntsville, AL
Posts: 129
Likes: 0
Received 0 Likes on 0 Posts
Default exponential definition please,

good evening,

my futaba has a setting for exponential, and i have them all set at 0% value as it's default setting. i see this option come up on the screen as i adjust my hi and low rates while setting up a new install. asking here how this applies to the flight controls and what it's intended use is.?
thanks in adv.
Old 11-04-2007, 07:59 PM
  #2  
Campgems
Senior Member
 
Join Date: Feb 2006
Location: Arroyo Grande, CA
Posts: 4,465
Likes: 0
Received 1 Like on 1 Post
Default RE: exponential definition please,

0% expoential is a linear movement of stick and control surface. Negitive exponential requires more movement of the stick near the center position and goes to full at full movment of the stick. A positive exponrntial will give more movement near the enter of the throw. If you are one that tends to be a little harsh on the sticks, some expo is a good thing. I fall into that catagory and I use -50% in both directions on my ailerons. Near the same on the elevator. For the throttle, you can play with it to get a near linear engine response. If you have Expo on your transmitter, it should show a graph of the servo movement.

Here are shots of my Futaba 9CAP Expo screens the first is with 0%. and the line goes up an equal amount as movement.

The second is with -50% and as you can see the servo movement is less per unit of stick movement untill you get to full travle

THe third is with +50% and here the movement is more untill you get to full stick travel.

Just remember, you set each direction individually. You can get some really screwy responses if you don't keep things moving coordinated. I about lost my plane last week because I had screwed up the movement and the results were noting like what I was trying to do.


Don
Attached Thumbnails Click image for larger version

Name:	Yw67749.jpg
Views:	12
Size:	84.5 KB
ID:	797124   Click image for larger version

Name:	Ql33301.jpg
Views:	15
Size:	75.7 KB
ID:	797125   Click image for larger version

Name:	Uz68659.jpg
Views:	13
Size:	74.0 KB
ID:	797126  
Old 11-04-2007, 08:05 PM
  #3  
Cyclic Hardover
Senior Member
My Feedback: (3)
 
Cyclic Hardover's Avatar
 
Join Date: May 2002
Location: New Mexico,
Posts: 7,296
Likes: 0
Received 1 Like on 1 Post
Default RE: exponential definition please,

Another version is to me makes the sticks feel sloppy. I have 10% negative on all my planes as thats all I want. You really don't want positive expo. Lets say you dial in 50%neg expo. What's going to happen up in the air is your wanting to make a simple left turn and your moving and moving and moving the stick to the left and nothing is happening until "wham", there it goes.

Very sloppy. You get use to it after a while but its a personal preference. You can put in 10% to start off and probably wont know the difference. Has nothing to do with dual rates as many sometimes confuse the two

If you accidently go positive. all you need to do is just think about moving the stick and the plane will come around, land at your feet , look you straight in the face and tell you "don't you ever &^%$# do that to me again!"
Old 11-04-2007, 08:08 PM
  #4  
Jester241
Senior Member
 
Jester241's Avatar
 
Join Date: Aug 2007
Location: MCALISTERVILLE, PA
Posts: 683
Likes: 0
Received 0 Likes on 0 Posts
Default RE: exponential definition please,

I usually run my expos on my elevators and ailerons and rudder at -25-30%.It helps alot during landing and takeoffs to NOT overreact on the controls. Just make sure you set it negatively and not positively.

It is a somewhat noticable difference and I highly recommend it to newer pilots like me.
Old 11-04-2007, 11:06 PM
  #5  
David Cutler
Senior Member
 
David Cutler's Avatar
 
Join Date: Sep 2002
Location: Los Angeles, CA
Posts: 2,162
Likes: 0
Received 0 Likes on 0 Posts
Default RE: exponential definition please,

As the others have said, expo makes it easier to be accurate in the middle of the throws (for landing etc) because the middle is less sensitive, but beware of one thing...

If you are flying inverted and have to have a small amount of 'down' to keep it level (quite common) don't forget the area you may now be in to control the plane may be in a faster reacting (more sensitive) area of the curve and this will make flying inverted more difficult if you have too high an expo dialed in.

-David C.
Old 11-04-2007, 11:36 PM
  #6  
JDV500
Senior Member
Thread Starter
 
JDV500's Avatar
 
Join Date: Oct 2007
Location: Huntsville, AL
Posts: 129
Likes: 0
Received 0 Likes on 0 Posts
Default RE: exponential definition please,

thanks all,
i understand completely now, great stuff. i need to incorperate this into my flying and will try some mild "negative" setting's later this week., i should print this to reread off-line to enforce the particulars you all mentioned above. at my stage of the game here, slosh in the controls would be a plus.

up till now,,,** what i did was locate the control rods at the far ends of the control horns to minimize the servo throws......also spent more flight time recovering from overeacting then actually working on the meneuver i was trying....
thanks don for the pics, that line graph shows a great visual of the delay in movement, or softening the authority...

cyclic, an ole cobra guy huh? i crewed them back at ft. hood in the late 80's.

thanks again everyone.
Old 11-04-2007, 11:55 PM
  #7  
Cyclic Hardover
Senior Member
My Feedback: (3)
 
Cyclic Hardover's Avatar
 
Join Date: May 2002
Location: New Mexico,
Posts: 7,296
Likes: 0
Received 1 Like on 1 Post
Default RE: exponential definition please,

Yeh, my time was from 75-95
Old 11-05-2007, 05:36 AM
  #8  
Rodney
Senior Member
 
Join Date: Dec 2001
Location: FL
Posts: 7,769
Likes: 0
Received 5 Likes on 5 Posts
Default RE: exponential definition please,

Depending on brand of radio, on Futaba and Hitec you set up negative expo. Some brands (like JR) set up positive expo as they define it the opposite way that Futaba does.
Old 11-05-2007, 09:31 AM
  #9  
RVman
Senior Member
 
Join Date: Jun 2003
Location: Guelph, ON,
Posts: 711
Likes: 0
Received 0 Likes on 0 Posts
Default RE: exponential definition please,

-25% is about linear contro surface movement. The servo movement makes the centre more sensitive than the end travel.
Old 11-05-2007, 10:34 AM
  #10  
JDV500
Senior Member
Thread Starter
 
JDV500's Avatar
 
Join Date: Oct 2007
Location: Huntsville, AL
Posts: 129
Likes: 0
Received 0 Likes on 0 Posts
Default RE: exponential definition please,

right, thanks.

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.