You can certainly build something that LOOKS LIKE an airplane, but it is difficult to believe that it will have the structural integrity to resist the forces that it will have to endure.
What is the shear strength of teh plastic around those holes where you have put zip ties? Airframe manufacturers spend a great deal of time drilling, inspecting, even x-raying rivet holes... because that is where cracks start.
why not just make it a big R/C un-manned rig...
how can it support the weight of a human, an engine, fuel, controls?? It looks great but do you think it might shake apart going down the runway at 50mph...using tape & zip ties to hold it together??
I don't want to see you guys getting hurt... make sure your buddy has a will and that he has signed an ironclad safety disclaimer, or his family may sue to pay for his care and feeding for the next 40 years.