Employing control surface model in preliminary aircraft design software

Abstract

Many aircraft design software packages are available in the market. Some of them are intended for preliminary design phase. These packages investigate the aircraft stability and controllability through the stability model to get the dimensional and non-dimensional derivatives. For students and fresh engineers, these derivatives are ambiguous and do not give a well-defined consideration about the influence of the control surface sizing on them.Therefore, adding the control surface model to preliminary software will assist, enhance, and improve students' knowledge, sympathy, and investigating studies. This paper presents the control surface model for use in preliminary aircraft design software. The model consists of three sub-models. Each sub-model is involved to perform the sizing of one of the primary conventional control surfaces. The aileron represents the first sub-model. The elevator represents the second sub-model, while the rudder represents the third sub-model. A flowchart for each sub-model is provided.

Preliminary control and stability analysis of a long-range eVTOL aircraft

“…The aileron span is found by assuming the inner and outer positions, 𝑏 1 and 𝑏 2 respectively, leading to 𝑏 𝑎 = 𝑏 2 − 𝑏 1 as can be seen in Figure 11. The chosen values and ranges of the geometric parameters are summarised in Table 3 as seen in literature [18].…”

“…A maximum deflection of 𝛿 𝑎 𝑚𝑎𝑥 = ±30 deg is assumed. Furthermore, a particular attention must be noted on the range of 𝑆 𝑎 /𝑆 𝑖 (which can be seen in Table 3), as for conventional aircraft the typical range is 0.05-0.1 [18]. This difference is taking into account the tandem wing nature of the eVTOL, hence 𝑆 𝑖 can reach values that are less than half the value of the total area 𝑆.…”

“…where 𝑏 is the span of the entire aircraft. Finally, 𝜏 𝑎 is the aileron effectiveness that can be estimated using Equation 37 [18]. With all the aforementioned, it is now possible to proceed with the sizing procedure.…”

“…Thirdly, it must be understood that the elevator and aileron are placed on both wings of the aircraft (analogous to an aircraft with both a canard and a tail for the elevator), leading to the summing nature of the elevator control derivative derived from Equation 31 and roll control derivative equations. Finally, for 𝐶 𝑙 𝛿𝑎 , the equation is derived and corrected with a combined method using strip theory [20] and [18], as explained in subsubsection III.C.3.…”