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Old Jan 07, 2008, 04:08 PM
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how to downsize .46 size plans to .15 size plans

i have some airplane plans of .40 - .46 engine size . please help me how to convert them to .15-.25 engine size. how much should i reduce the original plan size.please help me
thanx
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Old Jan 07, 2008, 06:19 PM
Zor
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Quote:
Originally Posted by dhanu76
i have some airplane plans of .40 - .46 engine size . please help me how to convert them to .15-.25 engine size. how much should i reduce the original plan size.please help me
thanx
About 2/3. Anyone agrees ?
The method to do it depends on your facilities.
Zor
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Old Jan 07, 2008, 06:43 PM
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Scale it enough to end up with between 400 to 450 sq inches for the .15 size or 450 to 500 sq inches for the .25 size. The size you end up at within the range depends on what the flight mission is like.

If it is a really wood filled design plan on reducing the sizes and amounts of wood in order to keep it lighter.
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Old Jan 08, 2008, 05:49 PM
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You would really have to be more specific about the type of aircraft and how you want it to fly. Lots of hot rod type airplanes designed for a .40 don't have more than 500 square inches, the quicky 500 racer comes to mind. I would reccomend finding a similar design for the engine size you want with the flying qualities you want, determine how much wing area it has then divide that number by the area of the wing of your design at it's current size. That will give you a reduction factor you can use when you take your plans to a copy shop and have them reduced. Hope that helps, John.
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Old Jan 08, 2008, 06:28 PM
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What's the plane?

Some planes work well being a little larger for the engine size and some smaller.

If you let us know the plane you want to do it to we can probably help make a better decision
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Old Jan 09, 2008, 04:37 PM
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East Anglia, UK
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Quote:
Originally Posted by Zor
About 2/3. Anyone agrees ?
The method to do it depends on your facilities.
Zor
I agree.

Maybe 3/4 to make wood sizing easier..
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Old Jan 12, 2008, 10:50 PM
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Have an engineer neighbor in my office who is constantly needs blue prints scanned and blown up or reduced. He highly recommends Kinkos for the work.

Tom
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Old Jan 13, 2008, 08:31 AM
Zor
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Quote:
Originally Posted by dhanu76
i have some airplane plans of .40 - .46 engine size . please help me how to convert them to .15-.25 engine size. how much should i reduce the original plan size.please help me
thanx
Hello again "dhanu76",

Keep in mind that reducing the size of a drawing by whatever method is used, photo copyer, reduced digital photogaphy, does reduce everything on paper.

It does not mean that _ _ _ as example below _ _ _
Reduction half size 1:2 . The 50"wing span becomes 25". The airfoil chord 9" becomes 4.5 " and so on like he stringers that were 3/16" x 3/16" now show on paper 3/32" x 3/32".

BUT that is NOT the way to build a reduced scale model plane.
A complete revision of the size of the components used is in order and that depends, as you already read from others the type of flying you intend to do, how strong you expect your airplane to be. That also explain the selection of the scale factor going from 0.46 to 0.15 engine displacement and power ratio available. Displacement of an engine is not the only factor affecting the power available.

Just some thinking from Zor. Enjoy your day.
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Old Jan 13, 2008, 09:47 AM
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A good way to get an idea re: wood size is to look over a similar plane in plans or kit and see what sizes it used. Get you in the ball park anyway.

Tom
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