function wcl() {
var WingArea = calc.WingArea.value;
if (WingArea == '')
	{alert('Wing Area must be entered.'); calc.WingArea.focus();return false;}
if (WingArea != parseFloat(WingArea) || WingArea <= 0)
	{alert('Wing Area is invalid (must be a number above 0).');calc.WingArea.focus();return false;}

var Weight = calc.Weight.value;
if (Weight == '') {alert('Weight must be entered.');
	calc.Weight.focus();return false;}
if (Weight != parseFloat(Weight) || Weight <= 0)
	{alert('Weight is invalid (must be a number above 0).');calc.Weight.focus();return false;}

var WingSqft = WingArea / 144;
var WingLoading = Weight / WingSqft;
var WingLoadMetric = WingLoading * 3.0515;
var WingAreaMetric = WingSqft * 9.290304;
var WeightMetric = Weight * (28.35);
var WingAreaSqrt = Math.sqrt(WingSqft);
var WCL = WingLoading / WingAreaSqrt;

calc.WingAreaMetric.value = Math.round(10 * WingAreaMetric) / 10;
calc.WeightMetric.value = Math.round(WeightMetric);
calc.WingLoad.value = Math.round(100 * WingLoading) / 100;
calc.WingLoadMetric.value = Math.round(10 * WingLoadMetric) / 10;
calc.WingCubeLoad.value = Math.round(10 * WCL) / 10;

return false;
}