Here you go:
In Excel:
GS=(AS^2+WS^2-2*AS*WS*COS(RADIANS(360-WA+HDGtrue)))^0.5
HDGtrue=TRACK-DEGREES(ASIN(WS/AS*SIN(RADIANS((WA-TRACK-180))))))
Or if you have an HP calculator and want to combine everything together:
TI&H=TRACK/TRACK*INT(DIST*60/(AS^2+WS^2-2*AS*WS*COS(360-WA+TRACK-ASIN(WS/AS*SIN(WA-TRACK-180))))^0.5)+0.001*INT(4+track-ASIN(WS/AS*SIN(WA-TRACK-180)))
GS=INT(DIST*60/INT(TI&H))
GS = Ground Speed
AS = Air Speed
WA = True wind angle
WS = wind speed
HDGtrue = True Heading
Track = True Track
Dist = length of leg to fly
TI&H = single figure output (eg 12.175) of time to fly and heading for leg (eg 12 minutes, 175 degrees)