You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: From Studying Real Hummingbirds to Designing Hummingbird-Like Robots—A Literature Review 
Chapter Title:  V. MORPHOLOGY OF WINGS AND GEOMETRIC SIMILARITY 
1. Abstract of Cited Paper (BIB001):  Lift production is constantly a great challenge for flapping wing micro air vehicles (MAVs). Designing a workable wing, therefore, plays an essential role. Dimensional analysis is an effective and valuable tool in studying the biomechanics of flyers. In this paper, geometric similarity study is firstly presented. Then, the ratio is defined and employed in wing performance estimation before the lumped parameter is induced and utilized in wing design. Comprehensive scaling laws on relation of wing performances for natural flyers are next investigated and developed via statistical analysis before being utilized to examine the wing design. Through geometric similarity study and statistical analysis, the results show that the aspect ratio and lumped parameter are independent on mass, and the lumped parameter is inversely proportional to the aspect ratio. The lumped parameters and aspect ratio of flapping wing MAVs correspond to the range of wing performances of natural flyers. Also, the wing performances of existing flapping wing MAVs are examined and follow the scaling laws. Last, the manufactured wings of the flapping wing MAVs are summarized. Our results will, therefore, provide a simple but powerful guideline for biologists and engineers who study the morphology of natural flyers and design flapping wing MAVs.

Literature Review:
Hummingbird wings are relatively small, narrow and extremely thin at the leading edge. Thanks to the unique wing shape, the sharp leading edge creates a leading edge flow that produces greater lift. Recent analytical studies have shown that the wing planform of hummingbirds which has more area towards the root (i.e. wing area centroid more towards the root) is very efficient in lift generation production. There are some factors to describe the wing shape such as a lumped parameter, aspect ratio and wing loading. Wing loading and aspect ratio are widely applied to quantify the size and shape of aircraft engineering and in studies of animal flight. In certain researches, relative wing loading (RWL) is utilized to estimate the aerodynamic performance BIB001 . In this paper, a flat and rigid wing in arbitrary form is hypothesized. The wing geometry parameters are presented in Fig. 8 . In this section, wing morphology and geometric similarity are to be studied and discussed. If birds are hypothesized to be a geometric similarity, then weight and lift can be expressed a characteristic length l during the steady-state flight. The entire wing surface A including two wings in vertebrate flyers with projected body area and volume V varies with characteristic length, that is,A ∼ l 2 , V∼ l 3 . In hovering or steady forward flight, it is reasonable to assume that the weight is proportional to lift forceF L . where, C L is the lift coefficient, ρ is the density, v t is the forward flight velocity. where , W is the weight, m is the mass of flyer, g is the gravitational acceleration. Total surface can be written as BIB002 A ∼ l 2 ≈ (m (3)