HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Feb 16, 2013, 12:57 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
6,009 Posts
Discussion
wing area X % scale =?

Maybe I didn't put i down quite right, but what I would like to know is this?

If you are going to increase the overall size of a plane by say 150%, and you have a given wing area (sq in) , how do you figure the new area out? A x 150%, just doesn't seem right.
TIA
CoolerByTheLake is offline Find More Posts by CoolerByTheLake
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 16, 2013, 01:12 PM
Registered User
ShoeDLG's Avatar
Germany, BW, Stuttgart
Joined Mar 2012
865 Posts
If you increase all dimensions by 150%, then you will increase the wing area by: 1.5x1.5 = 2.25, or 225%.
ShoeDLG is online now Find More Posts by ShoeDLG
Reply With Quote
Old Feb 16, 2013, 01:37 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
6,009 Posts
Thanks,
I was thinking it had something to do with being "squared" , just not sure on what and how. Now I have learned my one new thing for the day!!
CoolerByTheLake is offline Find More Posts by CoolerByTheLake
Reply With Quote
Old Feb 16, 2013, 03:40 PM
Registered User
Florida
Joined Aug 2004
4,166 Posts
Your thinking was correct. The increase would be 1.5 squared or 2.3 times the original area. If you wanted to have the new size to have 150% as much area as the original you would increase the linear dimensions by the square root of 1.5 or 1.2247 times.
Rodney is offline Find More Posts by Rodney
Last edited by Rodney; Feb 16, 2013 at 03:49 PM.
Reply With Quote
Old Apr 15, 2013, 11:59 AM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
6,009 Posts
OK, here's one more question. I'm trying to find sq.in (wing area) of a model which is 8.79% scale. Full size plane is 202 sq.ft. So do I take 8.79 x 8.79= 77.26/202=2.61 x144=375.84 sq.in.?
CoolerByTheLake is offline Find More Posts by CoolerByTheLake
Reply With Quote
Old Apr 15, 2013, 02:16 PM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
11,641 Posts
You need to convert the % to a decimal. So 8.79% is actually .0879.

So it's the size change squared times the full size area in sq feet times the conversion from sq ft to sq inches. Or;

.0879^2 x 202 sq feet x 144 sqin/sqft = 225 sq inches
BMatthews is offline Find More Posts by BMatthews
Reply With Quote
Old May 23, 2013, 07:36 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
6,009 Posts
Thanks for the help guys, but I'm doing something wrong here.

Where I think I'm going wrong is in figuring the scale. The full size plane has a WS of 40ft or 480" and 400sq/ft. . Model has WS of 53" -----sqft?
I took 53/480=9.056
So, using BMatthews formula .0905^2 x 400 sq/ft x 144 sqin/sqft = 471.7sqin

Now if I take 44.5" WS/480 =10.78
then .1078^2 x 400sqft x 144sqin/s1ft =669.3sqin? -shorter wing with more sqin? WRONG.
It has to be something simple I'm missing, HELP Please.
CoolerByTheLake is offline Find More Posts by CoolerByTheLake
Reply With Quote
Old May 24, 2013, 03:02 AM
Registered User
Staffs, UK
Joined Nov 2003
10,790 Posts
You're calculating the scale factor NOT the percentage change. Effectively your division is upside down which is why the calculations go astray.

Scale factor is Original size / Model size. 480 / 53 = 9.056

Percentage change is Model size/Original size (x 100)
53 / 480 = .1104 (or 11.04 %)
44.5 / 480 = .0927 (or 9.27%)

The percentage change also equals 100 / scale factor. I.e. if scale factor is 4 that's 100/4 or 25%, if scale factor is 8 that's 100/8 or 12.5%. For 53" span you got a scale factor of 9.056, which is a percentage change of 100/9.056 or 11.04

Steve
slipstick is offline Find More Posts by slipstick
Reply With Quote
Old May 24, 2013, 03:10 AM
Registered User
Cromer,Norfolk, UK
Joined Nov 2006
2,505 Posts
EDITED - I was being a numbnuts...
MCarlton is offline Find More Posts by MCarlton
Last edited by MCarlton; May 24, 2013 at 03:28 AM.
Reply With Quote
Old May 24, 2013, 06:18 AM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
6,009 Posts
slipstick, Thanks much, I knew something was astry, just could not pin point it.

To some it may seem a "Stupid"question, but I can't be the only one who doesn't/didn't know! It may help others later on, in a their quest for knowledge!

Having gotten the solution,I see where I went wrong-

The dividend is the number that is being divided. The divisor is the number that the dividend will be divided by. Had to look it up, it's been a long time since I have seen the inside of a classroom!!
CoolerByTheLake is offline Find More Posts by CoolerByTheLake
Last edited by CoolerByTheLake; May 24, 2013 at 06:27 AM.
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale X-83 flyjet seattle area lectroglide Aircraft - Electric - Airplanes (FS/W) 2 Mar 11, 2013 02:29 PM
.25 Low wing trainer LPU Sacramento area gravityking Non R/C Items (FS/W) 7 Feb 12, 2013 07:36 PM
Question Scale flying in the Los Angeles area firespit Scale Sailplanes 3 Jan 25, 2013 09:43 PM
Sold X-83 flyjet seattle area lectroglide Aircraft - Electric - Airplanes (FS/W) 2 Jan 18, 2013 09:04 AM
How do you scale down the wing area? Frank B Modeling Science 2 Nov 18, 2004 07:13 AM