The ship has an allright silhouette and the idea behind the shapes is OK as well. What goes amiss are the forms. It's looking a bit flat due to some pillow-shading. The wings have some unnecessary jaggies. Either make them into 1x1 lines or try and do it the hard way by antialiasing, which can be a bit hard without sacrificing outline quality.
I'll tell you what, before continuing this ship, try and render different basic shapes, like a cube, a cylinder, a pyramid and a torus. Just for practice. OUTLINES NOT ALLOWED! This way you'll learn to understand shapes better and maybe get the vocabulary to make this ship awesome.