Hi All I have lots of 40 glow plans, that I would like to downsize some and make then electric.. Thinking of downsizing 25%..Whats the best route to take..

Thanks Dan

Well, Kinkos or similar services have HUGE photocopiers that can shrink that sort of plan down. BUt then you'll need to know what can be lightened and what can be tossed out and what can or needs to be changed to suit the new size.

And you're reducing BY 25% to 75% of original or down TO 25%? Going down to 75% size isn't bad but you'll want to make some changes to wood sizes and construction methods to lighten the model for electric flying. BUt if you're looking at going down to 25% for parkflying then that's a whole other kidney! The outlines would be fine but the construction methods would need to change radically.

Hi Sorry my question wasn't clear enough..I will be reducing the plane by 25%..Question would the weight also be reduced by that 25%..

Thanks Dan

Going to 75% of the original size means you won't have much issue with most of the design changes. Try to shoot for the next smaller wood size in as many cases as you can but don't go to less than what is typical for the size of model that the design will come out to be. For example parts made from 1/16 will need to stay 1/16 but some 3/16 parts could be reduced to 1/8 where they are not flying surfaces. But if the horizontal and vertical tails on the full sized were made from 3/16 solid sheet then consider making them built up instead on the smaller version with 3/16 x 3/4 front and rear and 3/16 x 1/8 ribs. This will lighten the tail with little reduction in strength.

The new smaller model will need to be a lot less than 95% of the weight of the full sized to fly well. Part of this is that the wing area goes down by the square of the size ratio. So your .75 scale model will only have .75^2 = .56 of the wing area. On top of that the smaller model will require a lighter wing loading than the 40 version. So with both the area ratio in mind along with the lower wing loading number you'll be looking to make the new model be no more than 1/2 the weight of the 40 sized version for it to fly well and slow down well for landings.

Hi
Thanks Bruce for the helpful info..I just finished with a Cloud Dancer,that was reduced from a 60 WS to 46" WS..The plane came out much lighter than I thought IT would..Here's a pic next to the 40 size..It didn't fly as well as 40 size, got kinda mushy when IT slowed down.

Dan

PS The 46" WS electric was for power..