|
|
09-14-2010, 05:59 PM | #1 |
RCC Contributor
|
Static Margin
Alright, school me on static margin. Flew a plane today that was very unstable. punched some numbers and turns out the static margin was like about (-2%) What would a good number be for static margin is there alot of difference between say 5% and 15% as far as stability is concerned? New to all this stuff but i want a stable aircraft as i'm not looking to do 3d right yet. Any input is appreciated
|
. |
Sponsored Links - Subscribe to remove this ad. |
|
09-14-2010, 09:34 PM | #2 |
RCC Expert Contributor
I am: Brian C
Join Date: Aug 2009
Location: Collingwood Ontario
Radio of choice:
12x,DX7,DX3r, # of RCs: 40+
Feedback: 45 / 100%
Posts: 950
Total Props: 10
|
Re: Static Margin
What aircraft and set up is in question
__________________
Past Prez and Instructor Edenvale Radio Controlled Aircraft Club http://www.edenvaleflyers.ca/ |
. |
09-14-2010, 09:40 PM | #3 |
RCC Expert Contributor
I am: Brian C
Join Date: Aug 2009
Location: Collingwood Ontario
Radio of choice:
12x,DX7,DX3r, # of RCs: 40+
Feedback: 45 / 100%
Posts: 950
Total Props: 10
|
Re: Static Margin
__________________
Past Prez and Instructor Edenvale Radio Controlled Aircraft Club http://www.edenvaleflyers.ca/ |
. |
|
|
09-15-2010, 07:00 PM | #6 |
RCC Expert Contributor
I am: Brian C
Join Date: Aug 2009
Location: Collingwood Ontario
Radio of choice:
12x,DX7,DX3r, # of RCs: 40+
Feedback: 45 / 100%
Posts: 950
Total Props: 10
|
Re: Static Margin
I am curious as to why you use the static margin to balance your plane. I just have not ever seen anyone else mention it when balancing rc aircraft. Most pilots I know just use the center of gravity from the plan or calculate it.On a straight wing with parallel leading and trailing edges(like a piper cub). The normal ballance point would be 1/3 or 33% back from the leading edge. a sport or 3d aircraft would move that to 1/4 back or 25% or even further.As you move the balance point forward the aircraft gets more responsive but if you go too far it can end up uncontrolable. On the edge you have a tapered wing and without the plans you would need to calculate the mac (mean air chord) There was a really good article in one of the magazines on this.The best idea is to keep it nose heavy with fuel tank empty.Test fly it. If you want it more responsive move the c of g back in small stages. I am by no means an expert on the subject but I hope this helped.
Oh here it is the M.A.C. calculator and some ballancing articles http://www.geistware.com/rcmodeling/cg_calc.htm#mac
__________________
Past Prez and Instructor Edenvale Radio Controlled Aircraft Club http://www.edenvaleflyers.ca/ |
. |
09-15-2010, 07:32 PM | #7 |
RCC Contributor
|
Re: Static Margin
The reason I am asking about static margin was because the calculator I was using is the same one you sent me the first time. It requires you to input the static margin. Normally I would use the manual.or plans to determine my cg but this being a scratchbuilt I don't have that luxury. The designer/builder doesn't like to answer his pm's so I'm left to figure this out on my own. I will try it like this on Friday and if its still no good I will just go and buy a proven plane and trash this one.
|
. |
09-15-2010, 08:34 PM | #8 |
RCC Expert Contributor
I am: Brian C
Join Date: Aug 2009
Location: Collingwood Ontario
Radio of choice:
12x,DX7,DX3r, # of RCs: 40+
Feedback: 45 / 100%
Posts: 950
Total Props: 10
|
Re: Static Margin
I am sure it will be much better a negative statig margin puts the balance point behind the center of gravity. You should notice a big difference. I have seen some poorly built and/or repaired aircraft fly remarkably well. Let us know how it goes.
__________________
Past Prez and Instructor Edenvale Radio Controlled Aircraft Club http://www.edenvaleflyers.ca/ |
. |
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
Display Modes | |
|