Help with plan Size
 

I am planning to start to building my second plane and I found a lot of plans on the net , my problem is that I want to build a plane that suites my os 46 la and most plans are 60 size so how do i adjust the cad plans from 60 size to 40 size.

Help with plan Size
 

Well, you need to do two things. Cubic inches of engine does not always relate proportionately. You first have to recalculate the size of the existing airplane for the assigned power. Then you have to calculate the proposed power and proportion the relative size of the proposed A/C to that figure. There are formulae for this. Would suggest that this first phase be done with the use of published handbooks and some discussion in the aerodynamics section herein too.

Then, once you determine the new ratio, within AutoCAD is a command function of SCALE. You simply capture the entire drawing and insert this new proportion figure. In moderate sized models, there will be a noticible difference between 0.666 and 0.625 when re-scaled. Takes about three seconds to complete. Then, you need to go in and correct items such as wood thicknesses to more common fractional or metric sizes, which takes seemingly days to find everything.

It ain't simple nor fast, but can be done. It won't fly the same either.

Wm.

Help with plan Size
 

CBL gave you the educated way to do it and I agree with his method.

Here is a less scientific way of going about this task. Check out the specifications on a number of similar models including type, construction method, materials used, etc. that fly on the desired motor. You will find that a lot of the numbers will be similar, or at least close to each other. Guess-timate the wing area and use that number to find the desired span. Divide the new span by the old one to get the scale.

Remember, I didn't say this was the scientific way to approach this problem, but I have used it with (mixed) success in the past. And, the times it didn't work proved to be quite interesting.

I have to add that I only used this method when I could afford to throw away the time and money involved in the project.

Now for the easy way
 

Now that you know the proper way heres the easy way to do it. scropunge the net to find similar planes what their ws is. ie same thing the guys above are telling you to get your desired final outcome. then take plans to kinkos and tell them the wingspan on the plane you have and the desired wingspan they will figure out the resize percentage slapo your plans in their machine and print you out a set of plans at the proper scale. remember you have to get the plans printed somewhere why not let someone else do all the calculations.

Joe
PS it would also help greatly if you tell us what plane you are wanting to do? some people may have already done them saving you headaches

Help with plan Size
 

I go along with what CoosBay recomended but with a little twist.

If you can find some plan that's close to what you want then just use one of the free CAD programs to scale it to the right size without bothering with the wood size changes. If it's within 20% of the size you want anyway then the sizes will probably be fine. For blocks and the like you'll have to just use a ruler (gasp) and measure off the plan.

If it's a 3/4 reduction then it's easy to just use the next smaller size than what they call for in each case.

Use the scaling option in the CAD program to scale to the right size and then take the file to somwhere with a plotter for the printout. I gather Kinko's can do the photocopy thing. Cnances are they also can handle the computer DXF or DWG file as well. I'm in Canada so I dont' know but a phone call will soon answer that.

kinkos
 

kinkos will work with Tiff files ( depends on the area you live) and almost all will work with PDF files. DWG and DXF files they cant work with. kinda one of the reasons I said just let them reduce the plans as then you dont have to mess with finding out which files they can handle. I dont do it this way as I have a professional drafting printing company that can print for me from whatever type file I give them. But with the paper plans they are basically just zeroxing them to a reduced size and is a lot less hassles if you arent a very graphic versed person.

Joe

Re: kinkos
 

Don't know of many CAD's that save tiff's so that's a non starter.

I DO know that there are proper drafting/graphics outfits that can do CAD drawings. And since you'd need the proper size anyway.....

Or can Kinko's scale up to full size from an 8 1/2 x 11 directly? As in 6 or 8 times without getting into expensive in between prints?

Of course the in betweens make great 1/2 A models too....... :D

kinkos
 

well for starters Corel Draw can save as tiff and I believe autocad can export to tiff or at least BMP files.

Kinkows can print to 3 ft wide and 40 feet long and can enlarge to the size you want in 1 shot. they got a calculator thing that tells them tyhe scale factor and they just input that into the machine and whammo


Joe

PS the company I use can go to 3 ft by 90 ft hehehe so can do most full size plans just have to do in 3 ft wide segments :0)