RC India
Welcome Guest, please login or register.
 
Pages: [1]   Go Down
0 Members and 1 Guest are viewing this topic. Topic Tools Topic Tools 
Read
« on: July 05, 2009, 05:06:29 PM »
anwar
Administrator
Forum Hero

*****

Reputation Power: 141 
anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!
Offline Offline

City: Doha (Qatar) & Thrissur
State: Kerala
RC Skills: Advanced
Posts: 11619
Join Date: Mar, 2009

RC India - Flying and racing with open minds !




It is important for stable flight that you have checked the "center of gravity" (CG) of a plane before it goes up in the air. 

1) A lot of times, the manual will tell you where the CG of the airplane. What does one do if there is no manual for the plane ? How do you check the CG (where on the wing would you try to hold and lift it up) ? Is the rule of thumb to go for the highest point on the top part of the wing ?

2) Assuming one got the CG wrong, normally what do people do to fix it ?

NB: Just stimulating some discussion that will help beginners  Wink
« Last Edit: July 05, 2009, 05:10:49 PM by anwar » Logged

Hangar : Please see my introduction.
RC India forum and me : About this forum.
 

Read
« Reply #1 on: July 06, 2009, 04:55:29 PM »
anwar
Administrator
Forum Hero

*****

Reputation Power: 141 
anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!anwar is awe-inspiring!
Offline Offline

City: Doha (Qatar) & Thrissur
State: Kerala
RC Skills: Advanced
Posts: 11619
Join Date: Mar, 2009

RC India - Flying and racing with open minds !



Or is this question better framed as "how to determine leading edge for any given model/wing" ?
Logged

Hangar : Please see my introduction.
RC India forum and me : About this forum.
 

Read
« Reply #2 on: July 06, 2009, 05:43:27 PM »
Pikle6
Plane Lover
Forum Hero

*****

Reputation Power: 13 
Pikle6 has no influence.
Offline Offline

City: Navi Mumbai
State: Maharashtra
RC Skills: Beginner
Posts: 1050
Join Date: Apr, 2009

VTOL - Vertical Take Off & Landing



here's SOME NICE INFO
http://www.rcpowers.com/forum/blog.php?b=98


http://www.dailymotion.com/video/x7gwlx_noseheavyverticalstabilizers_tech

http://www.youtube.com/watch?v=NZtqZ2UhnDg&eurl=http%3A%2F%2Fwww.rcpowers.com%2Fforum%2Fblog.php%3Fb%3D98&feature=player_embedded
Logged

E.V.Subramanian
Yak55|EasyFly Glider 1.9m|Skyfun|Easystar II|Quad Talon V2|Mini Saturn
 

Read
« Reply #3 on: July 11, 2009, 07:25:17 AM »
saikat
Plane Lover
Forum Hero
*****

Reputation Power: 14 
saikat has no influence.
Offline Offline

City: Tezpur
State: Assam
RC Skills: Intermediate
Posts: 1130
Join Date: Jul, 2009



For Rc normal types you can't go wrong by taking an initial CG of 33% of chord.
Note this is for parallel chord wings - for tapered wings take mean average chord.



For freeflight - rubber or pylon type FF power - its about 50%.

if anybody wants to know more - give some specific examples and I 'll
take my best shot.


Here's another point for the sake of discussion - I,ve always wondered
if I have a sharply raked back rudder hinge line - will application
of left or right rudder also give some up elevator effect ?
Logged
 

Read
« Reply #4 on: July 11, 2009, 01:15:17 PM »
izmile
Plane Lover
Forum Hero

*****

Reputation Power: 7 
izmile has no influence.
Offline Offline

City: Reading (England)
State: OUTSIDE INDIA
RC Skills: Intermediate
Posts: 591
Join Date: Mar, 2009

I am a Corogamist!



Couple of my experience in designing an airplane wing with ease of CG balancing in mind.

1, Make your wing chord larger. Its is easier to balance a plane with wider wing chord than a plane with shotter wing chord. This is a simple concept - Imagine you are standing on a tight rope.. it would be better to balance yourself with a long pole in your hand than a short one.

2, Make the airfoil slightly thicker - relative to the model size. I do not have a hard number for the %age of thickness but I usually go with my instincts. - usually it would be about 10% of the chord length. I have noticed that thinner airfoils will have wing incidence issues and thicker ones are more forgiving.

-Ismail

Logged

"Anything can fly" - SPADs just prove that!
 

Read
« Reply #5 on: August 03, 2009, 10:09:33 PM »
TEJASCOOL007
Plane Lover
Active Member

**

Reputation Power: 2 
TEJASCOOL007 has no influence.
Offline Offline

City: KALYAN
State: Maharashtra
RC Skills: Beginner
Posts: 71
Join Date: May, 2009



CAN ANY ONE GIVE ME THE INFO ON CG OF A RC PLANE...Huh???

[Admin Note]: Merged with existing discussion on CG
« Last Edit: August 03, 2009, 10:14:53 PM by anwar » Logged

struggle is the only key to become airbone..!!!
 

Read
« Reply #6 on: August 31, 2009, 03:33:00 PM »
PankajC
Plane Lover
Forum Hero

*****

Reputation Power: 13 
PankajC has no influence.
Offline Offline

City: Delhi
State: Delhi
RC Skills: Beginner
Posts: 1022
Join Date: Jul, 2009

Learning to Fly



guys,
We usually talk about CG in terms of the balance wrt to the wings. What about the balance along the fuselage (nose to tail)?
Is it important?
How to check?

Pankaj
Logged

Spektrum DX6i | EP Pusher Trainer | EP CUB |
 

Read
« Reply #7 on: August 31, 2009, 05:19:21 PM »
tg
Plane Lover
Forum Hero
*****

Reputation Power: 1 
tg has no influence.
Offline Offline

City: Bangalore
State: Karnataka
RC Skills: Beginner
Posts: 553
Join Date: Oct, 2009



Yes, hold model nose to tail and check that both wings are balanced and level
Logged
 

Read
« Reply #8 on: February 04, 2010, 06:37:12 PM »
sriharishine
Plane Lover
Senior Member
***

Reputation Power: 3 
sriharishine has no influence.
Offline Offline

City: Coimbatore
State: Tamil Nadu
RC Skills: Beginner
Posts: 202
Join Date: Jan, 2010



For Rc normal types you can't go wrong by taking an initial CG of 33% of chord.

Hi saikat,

Can you explain me this point clearly since I could not get it clear. I mean the text "intial CG of 33% of chord".

For example, the Chord length is 6", wing span is 36" and the fuse lenght is 24" then what will you be CG? Can you try and let me know? (I mean for parallel chord wing - Gliders/SPADs)
Logged
 

Read
« Reply #9 on: February 04, 2010, 06:50:42 PM »
sriharishine
Plane Lover
Senior Member
***

Reputation Power: 3 
sriharishine has no influence.
Offline Offline

City: Coimbatore
State: Tamil Nadu
RC Skills: Beginner
Posts: 202
Join Date: Jan, 2010



Hi to all,

Here is a link to check CG of your RC plane with TWO simple techniques... It is really easy.

http://www.rc-airplane-world.com/balancing-rc-airplanes.html

I am sure it is very simple and useful technique.

Regards
Srihari
Logged
 

Read
« Reply #10 on: February 04, 2010, 06:51:17 PM »
PankajC
Plane Lover
Forum Hero

*****

Reputation Power: 13 
PankajC has no influence.
Offline Offline

City: Delhi
State: Delhi
RC Skills: Beginner
Posts: 1022
Join Date: Jul, 2009

Learning to Fly



What he means is that if you install the motor, battery etc, and the wings, mark out 1/3 of the wing chord from the leading edge (in hour example, 2" from front). then lift the model exactly at these points on the wing tip using things that are very small and blunt. The model should be balanced with just about 3-5 degree inclination towards the nose.
Logged

Spektrum DX6i | EP Pusher Trainer | EP CUB |
 

Read
« Reply #11 on: February 04, 2010, 07:29:48 PM »
sriharishine
Plane Lover
Senior Member
***

Reputation Power: 3 
sriharishine has no influence.
Offline Offline

City: Coimbatore
State: Tamil Nadu
RC Skills: Beginner
Posts: 202
Join Date: Jan, 2010



Thanks Pankaj, I understood.
Logged
 

Read
« Reply #12 on: February 16, 2011, 02:58:17 PM »
SunLikeStar
Forum Administrator
Forum Hero

*****

Reputation Power: 20 
SunLikeStar barely matters.SunLikeStar barely matters.
Offline Offline

City: Pune
State: Maharashtra
RC Skills: Intermediate
Posts: 1902
Join Date: Aug, 2010

High spirits we have: gravity we flout.



Good and free application for calculating CG.
http://home.arcor.de/d_meissner/W_Laengs4_V26.zip
Logged
 

Read
« Reply #13 on: April 20, 2011, 09:45:32 AM »
ashutoshn
Plane Lover
Active Member
**

Reputation Power: 2 
ashutoshn has no influence.
Offline Offline

City: Bangalore
State: Karnataka
RC Skills: Beginner
Posts: 95
Join Date: Jan, 2010



Center of gravity is generally at 25-35%. It can be found by balancing plane's wing on fingertips on vertical axis.

Question is should center of gravity be considered to lie on the wing's surface or somewhere below the wing and in the fuse. This is for a high winger plane.
« Last Edit: April 20, 2011, 09:58:11 AM by ashutoshn » Logged
 

Read
« Reply #14 on: April 20, 2011, 10:06:37 AM »
SunLikeStar
Forum Administrator
Forum Hero

*****

Reputation Power: 20 
SunLikeStar barely matters.SunLikeStar barely matters.
Offline Offline

City: Pune
State: Maharashtra
RC Skills: Intermediate
Posts: 1902
Join Date: Aug, 2010

High spirits we have: gravity we flout.



If you consider both roll and pitch axis then COG will always lie in the fuselage. But the CG rarely changes for the roll axis hence we generally check CG only on the pitch axis, by balancing plane's wing on fingertips.
Logged
 

Read
« Reply #15 on: April 20, 2011, 01:35:38 PM »
ashutoshn
Plane Lover
Active Member
**

Reputation Power: 2 
ashutoshn has no influence.
Offline Offline

City: Bangalore
State: Karnataka
RC Skills: Beginner
Posts: 95
Join Date: Jan, 2010



So for a easy star if the motor's thrust line is to be adjusted to pass thro the CG, then, should the CG be considered to be on the wing surface or in the fuse ?
Logged
 

Read
« Reply #16 on: April 20, 2011, 03:02:11 PM »
SunLikeStar
Forum Administrator
Forum Hero

*****

Reputation Power: 20 
SunLikeStar barely matters.SunLikeStar barely matters.
Offline Offline

City: Pune
State: Maharashtra
RC Skills: Intermediate
Posts: 1902
Join Date: Aug, 2010

High spirits we have: gravity we flout.



In the fuse. But why do you want to change the thrust angle, the default angle works good.
Logged
 

Read
« Reply #17 on: April 20, 2011, 04:11:02 PM »
rcpilotacro
Global Moderator
Forum Hero

*****

Reputation Power: 58 
rcpilotacro is on the verge of being accepted.rcpilotacro is on the verge of being accepted.rcpilotacro is on the verge of being accepted.rcpilotacro is on the verge of being accepted.rcpilotacro is on the verge of being accepted.
Offline Offline

City: Delhi
State: Delhi
RC Skills: Advanced
Posts: 5041
Join Date: Nov, 2010

Practice, and only Practice will make you perfect



Here is the Great Planes CG balancer, it is available here (http://www.greatplanes.com/reviews/gpmr2400-man.html), however a closer look, you can DIY easily. Here is the pic

great planes cg machine.jpg
Re: Building tip: How to check and adjust for CG of a plane
* great planes cg machine.jpg (13.02 KB, 245x300 - viewed 722 times.)
Logged

Gusty's Hangar and Introduction.

A Good pilot will practice until he gets it right,
A Great pilot will practice until he canít get it wrong.
 

Read
« Reply #18 on: April 20, 2011, 04:56:12 PM »
Vector
Plane Lover
Senior Member

***

Reputation Power: 2 
Vector has no influence.
Offline Offline

City: mumbai / pune
State: Maharashtra
RC Skills: Intermediate
Posts: 143
Join Date: Nov, 2010

"cleared for takeoff"



$$..better to build one i guess  Wink
Logged
 

Read
« Reply #19 on: April 21, 2011, 02:05:38 AM »
ashutoshn
Plane Lover
Active Member
**

Reputation Power: 2 
ashutoshn has no influence.
Offline Offline

City: Bangalore
State: Karnataka
RC Skills: Beginner
Posts: 95
Join Date: Jan, 2010



@ Vector (Amar?) , augustinev : I could have bought or built the stuff, but currently I am running low on vitamin-M and vitamin-T.

@ SLS: I had fixed my motor pod after a crash and subsequently lost stock prop inflight. A 6x4E prop (which should normally fit onto easy star) would not fit on mine. Then i realized that the thrust angle was incorrect. Went thro corrective operation of the motor pod. I have not yet flown the plane after repairs as I was not 100% sure. But with these diagrams I think the thrust line is almost correct w.r.t. the original thrust line. Can be sure only after I fly again.

DSC07170.jpg
Re: Building tip: How to check and adjust for CG of a plane
* DSC07170.jpg (59.7 KB, 800x600 - viewed 795 times.)
This post has 1 more images(s)/attachment(s). Please login or register to view them.
Logged
 

Read
« Reply #20 on: April 21, 2011, 09:53:19 AM »
SunLikeStar
Forum Administrator
Forum Hero

*****

Reputation Power: 20 
SunLikeStar barely matters.SunLikeStar barely matters.
Offline Offline

City: Pune
State: Maharashtra
RC Skills: Intermediate
Posts: 1902
Join Date: Aug, 2010

High spirits we have: gravity we flout.



It looks good just toss it at 50~60% throttle for the first flight and you should be fine Thumbs Up
Logged
 

Pages: [1]   Go Up
Jump to:  

Related Topics
Subject Started by Replies Views Last post
Building my first plane out of Coro « 1 2  All »
Tools, Materials and Building Techniques
Hellyflyer 47 17820 Last post October 29, 2010, 04:26:45 PM
by SunLikeStar
help in building plane ( pusher plane or glider ) « 1 2 3  All »
Electric Planes
vineet 51 32142 Last post July 15, 2017, 11:22:14 PM
by Kantesh
CHECK LIST FOR SCRATCH BUILDING FOAMIE RC PLANE
Beginners Zone
sagi8568 16 6544 Last post June 29, 2013, 09:12:00 PM
by aniket210696
Check this out - electric plane by NASA - Greased Lightning - GL-10
Chatter Zone
tg 0 3415 Last post May 04, 2015, 11:01:26 PM
by tg
fsi6s stick adjust
Chatter Zone
SKY KALAI 8 917 Last post May 10, 2020, 04:37:34 PM
by SKY KALAI