Coroplast Ver 4.0 - 150cm/43.5dm2 (called it ver 1.0 wing ) vs 170cm/51dm2 (called it ver 2.0 wing)

During the fly, it feels that the plane has less power than expected. The weight is about 3.7kg (not fill tank), the wing used is 150cm/43.dm2. If we calculate, the figure would be (see figures below). After changing the wing with wing ver 2.0, it changes the plane maneuverability/speed/etc. dramatically. It shows from the calculation below, lesson learned, it is not merely the power but it also depends on the wing load and watts per kg determining how your plane would fly ! ...

In summary:
- Calculate your WCL number and plane characteristics.
- Once you have the WCL, please take a loot at Watts/Kg your power RC plane installed.
Both will determine how your plane will fly beside other things such as control surface, length/width of your wing, location of your CG, and other things...

from http://www.ef-uk.net/data/wcl.htm
With ver 1.0 wing the calculation:

With ver 2.0 wing the calculation:

There are many excellent website to calculate Watts/Power requirements for your own design airplane, some examples:

http://www.motocalc.com/tutorial/
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Determining Power Requirements

Regardless of the motor, battery, and propeller eventually chosen, any airplane needs a certain amount of power to achieve a desired level of performance. One simply cannot get around the laws of physics. Because of this basic fact, a number of "rules of thumb" have been proposed based on a plane's power to weight ratio. For example, it is suggested that a plane have about 40 to 60 Watts of power per pound (88 to 132 W/kg) of aircraft for typical "sport" type flying. More aggressive aerobatic flying requires about 70 to 100 Watts per pound (154 to 220 W/kg).

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http://www.rcgroups.com/forums/showthread.php?t=29480
http://www.rcuniverse.com/magazine/reviews/976/ampd3.pdf