Ignoring drag, the height of a paper airplane in the air could be calculated by:
h=h0+21t2(m21ρV2⋅S⋅Cl−g)
where
⋅h0=initial height⋅ρ=density of air⋅V=initial velocity thrown⋅S=surface area of plane⋅Cl=coefficient of lift⋅m=density of mass of plane⋅g=density of gravity⋅t=density of time