Notices
Scratch Building, Aircraft Design, 3D/CAD If you are starting/building a project from scratch or want to discuss design, CAD or even share 3D design images this is the place. Q&A's.

plan enlargement

Old 02-14-2009, 10:30 PM
  #1  
1/4 flyboy
Thread Starter
My Feedback: (1)
 
Join Date: Feb 2002
Location: Hill City, MN
Posts: 122
Likes: 0
Received 0 Likes on 0 Posts
Default plan enlargement

Hello Guy's
I have a set of .40 size plans that I would like to blow up to .60size what the math work on this?
Thanks in advance
Old 02-14-2009, 11:21 PM
  #2  
w8ye
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,567
Likes: 0
Received 4 Likes on 4 Posts
Default RE: plan enlargement

About 110% - 112% they do it on the enlarger at the plans duplicating business
Old 02-14-2009, 11:59 PM
  #3  
1/4 flyboy
Thread Starter
My Feedback: (1)
 
Join Date: Feb 2002
Location: Hill City, MN
Posts: 122
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

Thanks for the help
so how does a guy figure that out?
Old 02-15-2009, 12:06 AM
  #4  
w8ye
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,567
Likes: 0
Received 4 Likes on 4 Posts
Default RE: plan enlargement

If you are talking about the percentage of enlargement, I compare the 40 size of a kit or ARF with the 60 size of the same ARf or kit and figure the percentage increase or decrease.
Old 02-15-2009, 12:15 AM
  #5  
All Day Dan
My Feedback: (5)
 
All Day Dan's Avatar
 
Join Date: Dec 2002
Location: MANHATTAN BEACH, CA
Posts: 4,605
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

A good wing area for a .60 size engine is around 800 square inches. Take the wing area of the .40 size plane and divide it into 800. Take the square root of that number. The number should come out around what w8ye recommends. Dan.
Old 02-15-2009, 12:18 AM
  #6  
w8ye
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,567
Likes: 0
Received 4 Likes on 4 Posts
Default RE: plan enlargement

For example the Goldberg Tiger 40 = 61" and the Tiger 60 is 70" then divide 70 by 61 and you get 1.15 or 115%

Super Sportster 40 = 55" and the Super Sportster 60 = 61" then divide 61 by 55 and you get 1.11 or 111%

Four Star 40 = 59.75" and the Four Star 60 = 71" then divide 71 by 59.75 and you get 1.19 or 119%

Old 02-15-2009, 10:47 AM
  #7  
squeakalong
Senior Member
My Feedback: (8)
 
Join Date: Feb 2008
Location: Interlochen, MI
Posts: 820
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

Good examples, w8ye and Dan; it's information that can help lots of folks get the model plane sized as they want.

Soft landings.
Old 02-15-2009, 12:50 PM
  #8  
w8ye
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,567
Likes: 0
Received 4 Likes on 4 Posts
Default RE: plan enlargement

I have a friend the built a World Models Robinhood 99 some yrs ago

He scaled down the plans at the blue print store

He has made a Robinhood 80, 70, & 50 and enjoyed them all

I have another friend that scaled up a 110% Slow Poke at Office Max. Installed a Saito 72 was a great flyer
Old 02-15-2009, 05:52 PM
  #9  
John 38
Senior Member
 
Join Date: Dec 2006
Location: not applicable, UNITED KINGDOM
Posts: 177
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

the above examples using commercial kits are a good basis for scaling up, but if you cannot find such an example to suit your requirments, then following might help.

when you scale up a model, the wing area goes up by the square of the scale up - eg scaling up by 20% gives a wing area increase of ( 1 + 0.2 ) x (1 + 0.2 ) which gives 1.44 or 44% increase in area.

the volume of the plane or more specifically, the material and its weight used in construction , increases by the cube of the scale up , ie 1.2 x 1.2 x 1.2 = 1.73 or an increase in weight of 73%.

this estimate will be affected by any major changes in material or construction particularly if scaling up to very large models, but for modest scale up it is a good estimate.

I keep the power weight ratio the same and in this example the power increase needed would be about 70%.

Working backwards from the requirement to scale up from a 40 to a 60 engine, simply take the cube root of the ratio of the power change , ie 60/40 = 1.5 and the cube root of 1.5 is 1.15 - that is a scale up of 15% which is similar to the recommendations above.

I have scaled up Goldbergs 42"cessna skylane to 84" and also Vic Smeeds Mamselle from 38" free flight to 72" and then to 108" for R/C and power came in just under the estimates from above, but I built them very light.

hope you find this useful

John
Old 04-12-2010, 09:37 PM
  #10  
BryanSinHou
Junior Member
 
Join Date: Jun 2007
Location: San Antonio, TX
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

All the above is for the wing and engine increase. What about the fuse enlargement? Do I simply add 44% to the 40 sized dimensions on the plans, the same as the the wing? The plane I want to scale up is a RCM plan "Northrop Eagle II" that has a relatively short tail moment (distance between TE of wing to LE of tail feathers). I have been told that due to this, I have to be sure to keep the proportion the same. The 40 size flies so well, straight and true with no bad flying characteristics. I want to get into large planes, so I am eager to get a larger version of this plane flying. Thanks in advance, Bryan
Old 04-12-2010, 09:46 PM
  #11  
w8ye
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,567
Likes: 0
Received 4 Likes on 4 Posts
Default RE: plan enlargement

I always just scaled up everything the same percentage
Old 04-13-2010, 04:55 AM
  #12  
John 38
Senior Member
 
Join Date: Dec 2006
Location: not applicable, UNITED KINGDOM
Posts: 177
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

Bryan,

the example I gave was for a 20% scale up which applies to all linear dimensions of the complete model - ie the fuselage length, breadth and height are all increased by 20%.

A 20% scale up leads to a 44% increase in wing area and an approximate 73% increase in weight.

I then use these figures as a guide to establish power and wing loading.

Hope this clarifies it for you

John
Old 04-13-2010, 08:47 AM
  #13  
limeybob
My Feedback: (6)
 
limeybob's Avatar
 
Join Date: May 2003
Location: Rockwall, Tx, TX
Posts: 997
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement


ORIGINAL: John 38

the above examples using commercial kits are a good basis for scaling up, but if you cannot find such an example to suit your requirments, then following might help.

when you scale up a model, the wing area goes up by the square of the scale up - eg scaling up by 20% gives a wing area increase of ( 1 + 0.2 ) x (1 + 0.2 ) which gives 1.44 or 44% increase in area.

the volume of the plane or more specifically, the material and its weight used in construction , increases by the cube of the scale up , ie 1.2 x 1.2 x 1.2 = 1.73 or an increase in weight of 73%.

this estimate will be affected by any major changes in material or construction particularly if scaling up to very large models, but for modest scale up it is a good estimate.

I keep the power weight ratio the same and in this example the power increase needed would be about 70%.

Working backwards from the requirement to scale up from a 40 to a 60 engine, simply take the cube root of the ratio of the power change , ie 60/40 = 1.5 and the cube root of 1.5 is 1.15 - that is a scale up of 15% which is similar to the recommendations above.

I have scaled up Goldbergs 42''cessna skylane to 84'' and also Vic Smeeds Mamselle from 38'' free flight to 72'' and then to 108'' for R/C and power came in just under the estimates from above, but I built them very light.

hope you find this useful

John
john, very good.
Here it is in graphic form
Attached Thumbnails Click image for larger version

Name:	Ge96288.jpg
Views:	14
Size:	120.2 KB
ID:	1417365  
Old 04-13-2010, 11:34 AM
  #14  
John 38
Senior Member
 
Join Date: Dec 2006
Location: not applicable, UNITED KINGDOM
Posts: 177
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

(B)limeybob,
sorry - coudn't resist the pun.

is this a commercial program or all your own work ??

john
Old 04-13-2010, 12:17 PM
  #15  
limeybob
My Feedback: (6)
 
limeybob's Avatar
 
Join Date: May 2003
Location: Rockwall, Tx, TX
Posts: 997
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement


ORIGINAL: John 38

(B)limeybob,
sorry - coudn't resist the pun.

is this a commercial program or all your own work ??

john
John, Ha Ha, but you are on the money.

Yes, on both accounts, its on my web site, I wrote this in Visual Basic 5 about 5-6 years ago, so its a bit ancient but it does work, even with Vista, I use it all the time as I do a lot of CAD design work for RC.
Bob
Old 04-13-2010, 12:23 PM
  #16  
limeybob
My Feedback: (6)
 
limeybob's Avatar
 
Join Date: May 2003
Location: Rockwall, Tx, TX
Posts: 997
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement


ORIGINAL: John 38

(B)limeybob,
sorry - coudn't resist the pun.

is this a commercial program or all your own work ??

john
John, also, it was set up to take the parameters from a full size aircraft, but will work for any scale conversion.

The intent was to be able to design a scale flying airplane for scale competition.

The software has lots of other stuff too.
Bob
Old 04-15-2010, 11:06 PM
  #17  
BryanSinHou
Junior Member
 
Join Date: Jun 2007
Location: San Antonio, TX
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

Thanks John, W8ye, and limeybob! I'll take that into consideration. I have a new workshop being built / powered now (12' x 24') and want to find a project to "break it in". I'll keep you updated when i start the project.
Bryan
Old 04-16-2010, 12:08 AM
  #18  
w8ye
My Feedback: (16)
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,567
Likes: 0
Received 4 Likes on 4 Posts
Default RE: plan enlargement

Good luck

Enjoy

Jim
Old 04-16-2010, 11:07 AM
  #19  
ARUP
Senior Member
 
Join Date: Jan 2007
Posts: 2,343
Likes: 0
Received 0 Likes on 0 Posts
Default RE: plan enlargement

RCScalebuilder.com has some tutorials and threads about it, too!

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 - Do Not Sell My Personal Information

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.