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

Rudder and elevator control problem

Old 08-07-2019, 02:46 PM
  #1  
Jondon51
New Member
Thread Starter
 
Join Date: Aug 2019
Posts: 8
Default Rudder and elevator control problem

Hi all , I have a rudder elevator sailplane 3 m and it takes about 3 seconds for the turn to kick in .the c of g is a bit nose heavy but I can't understand why it's not turning quickly enough . I have asked for the polyhedral angle from the supplier but have not got anything back yet .. Any ideas.
Jondon51 is offline  
Old 08-07-2019, 05:08 PM
  #2  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,827
Default

I used to fly flat field thermal jobs similar ... Rud / Elev .... but response was certainly better than 3 secs.

It was always a balance though of agile turn without causing her to bank excessively to be able to hold the thermal.

So question is :

1. Is this a powered sailplane or bungee launched ?
2. Does she start to 'flat turn before banking ?
3. The 3 secs - are you saying that as the point you visually see the model bank or flat turn ?
4. Does the turn tighten if rudder is held ? Such that wing then progressively falls of till she spins ...

I would first of all edge that CoG back ....
solentlife is online now  
Old 08-07-2019, 06:33 PM
  #3  
Jondon51
New Member
Thread Starter
 
Join Date: Aug 2019
Posts: 8
Default

Yes it's powered , it just banks over but it should turn quicker than that. Did not leave it that long to go in a spin. I will get a proper cofg balancer next time . I should have glided it and moved the battery further back until I got a decent glide the plane is from hyper flight in the uk and it's introduction. S5j model. Thanks for your help. What do you think of me getting a refund if it won't fly ha ha .
Jondon51 is offline  
Old 08-07-2019, 09:18 PM
  #4  
quorneng
Super Contributor
 
quorneng's Avatar
 
Join Date: Jul 2008
Location: Cheshire, UK
Posts: 2,062
Default

My own view is that a 3m glider will always be slow to turn on rudder only unless it has plenty of dihedral and a big rudder.
With modern small light servos there is no technical reason why ailerons cannot be fitted then with the appropriate controls a turn will happen and be as tight as you like!
Include aileron differential movement and the rudder becomes just a 'trim' control to keep the turn 'aerodynamically efficient' and free from any yaw.
quorneng is offline  
Old 08-07-2019, 09:47 PM
  #5  
Panther
Super Contributor
 
Panther's Avatar
 
Join Date: Oct 2012
Location: South East Queensland, Australia
Posts: 1,639
Default

Another reason is you may be flying too slow. Try flying faster, and, yes, your CG may be too far forward but it would have to be a long way out.
S5J or F5J?
Panther is offline  
Old 08-08-2019, 12:19 AM
  #6  
Jondon51
New Member
Thread Starter
 
Join Date: Aug 2019
Posts: 8
Default

It's an f5j model . I turned it to come in for a landing and it really dived and I was slow to react. Rebuilding it now. Get myself a proper balancer next.
Jondon51 is offline  
Old 08-08-2019, 12:22 AM
  #7  
Jondon51
New Member
Thread Starter
 
Join Date: Aug 2019
Posts: 8
Default

It's a polyhedral wing . Would you put ailerons on the outboard wing.
Jondon51 is offline  
Old 08-08-2019, 06:26 AM
  #8  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,269
Default

I agree, you are flying it to slow, give the rudder and elevator more throw, that is a high speed sail plane thats not ment to go slow at all. get more practice with a 2 meter power glider thats ment to fly slower
CHELLIE is offline  
Old 08-08-2019, 09:42 AM
  #9  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,827
Default

Originally Posted by Jondon51 View Post
It's a polyhedral wing . Would you put ailerons on the outboard wing.
You don't put ailerons ... polyhedral is designed to not use them. It gives large area lift as well as ample dihedral for rud / ele control.

In fact if flying slow and coming into land - ailerons could make situation worse.
solentlife is online now  
Old 08-08-2019, 02:03 PM
  #10  
Jondon51
New Member
Thread Starter
 
Join Date: Aug 2019
Posts: 8
Default

If you don't put ailerons on a 3 metre sailplane why does hyper flight sell one for 450 pounds. I have the maximum throws on the model and the rudder should be big enough . I don't know if it's going too slow but it's supposed to be a floater . Thanks for the input though.
Jondon51 is offline  
Old 08-08-2019, 02:50 PM
  #11  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,827
Default

Think you are over thinking this.

The design is such that designer did not consider ailerons needed, Polyhedral wings for years have served well in Rud Ele models .... I've had a number of large sailplanes without any motor that have been Rud Ele only Polyhedral.

Of course there are exceptions and you can find a model that has ailerons. It does not mean that its the answer to your problem.

We are all trying to help and consider what can get you flying better.

i know from my own models ... a powered sailplane tends to make one use the motor to keep it flying instead of flying as it should ...
solentlife is online now  
Old 08-08-2019, 03:38 PM
  #12  
Jondon51
New Member
Thread Starter
 
Join Date: Aug 2019
Posts: 8
Default

Ok thanks I will test glide it the next time and get a good glide angle and then power up .
Jondon51 is offline  
Old 08-08-2019, 06:45 PM
  #13  
Panther
Super Contributor
 
Panther's Avatar
 
Join Date: Oct 2012
Location: South East Queensland, Australia
Posts: 1,639
Default

I just put my fingertips under the wings close to the fuselage about 1/3 of the way back from the leading edge or close to where the wing is thickest. The plane should only just tip forward. This gives you a good CG starting point. No need to buy a CG balancer. Waste of money in my opinion.
Panther is offline  
Old 08-08-2019, 08:42 PM
  #14  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,827
Default

Originally Posted by Panther View Post
I just put my fingertips under the wings close to the fuselage about 1/3 of the way back from the leading edge or close to where the wing is thickest. The plane should only just tip forward. This gives you a good CG starting point. No need to buy a CG balancer. Waste of money in my opinion.
I can certainly say the Hobby King CoG machine is c**p !!

Block of wood with two pencils with rubber eraser tips uppermost is better !!

And always test balance by having models greatest weight lowest .. ie high wing model upright, low wing model inverted etc.
solentlife is online now  
Old 08-09-2019, 12:54 PM
  #15  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,269
Default

Originally Posted by Jondon51 View Post
If you don't put ailerons on a 3 metre sailplane why does hyper flight sell one for 450 pounds. I have the maximum throws on the model and the rudder should be big enough . I don't know if it's going too slow but it's supposed to be a floater . Thanks for the input though.

Air flow over control surfaces = Aircraft Control , Fly a little faster for better control
CHELLIE is offline  

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


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

Page generated in 0.10696 seconds with 12 queries