Wing Arrangements

Wing arrangements have a significant influence on the types of missile control to be used. Three types of wing arrange­ments are discussed here.

1. Cruciform. The most commonly used configuration in missile design is the cruciform, which possesses four wing surfaces and four tail surfaces. There are several major advantages in the use of this type of configura­tion: (i) fast response in producing lift in any direction, (ii) identical pitch and yaw characteristics, and (iii) sim­pler control system as the result of item (ii). One of the most important aspects associated with a cruciform de­sign is the orientation of the tail surface with respect to the wing planes. The significant conclusion from consid­erable experience and experimental data was that an in-line tail surface (i. e., all the four tail surfaces are in the same orientations as the four wing surfaces) pro­vides the best overall aerodynamic characteristics for most missile applications. The other possible wing-tail geometrical relation is called interdigitated configura­tion where there is a 45° separation between the wing and tail orientation. For a cruciform missile, the most difficult parameter to determine accurately is the in­duced rolling moment. The rolling moments arise when­ever the missile simultaneously executes pitch and yaw maneuvers that are unequal in magnitude. Such ma­neuvers result in unequal or asymmetric flow patterns over the aerodynamic lifting surface; consequently, roll­ing moments are induced on the airframe. Hence, roll stabilization or control is a critical issue for cruciform missiles.

2. Monowing. The monowing arrangements are generally used on cruise-type missile (i. e., missiles design to cruise for relatively a long range like crewed aircraft). This type of design is generally lighter and has less drag than the cruciform configuration. The wing area and span are, however, somewhat larger. Although the monowing missile must bank to orient its lift vector in the desired direction during maneuvering flights, the response time may be sufficiently fast and acceptable from a guidance-accuracy standpoint. The induced-roll problem for the monowing configuration is substantially less severe than that associated with the cruciform con­figuration. A separate set of lateral control surfaces, such as flaps, spoilers, and wing-tip ailerons, is gener­ally used in a monowing design. This stems from the fact that the canard or tail surfaces that are usually employed for pitch control on monowing design are gen­erally inadequate for lateral control.

3. Triform. This type of wing arrangement, which em­ploys three wings of equal area spaced 120° apart, is seldom used because no noticeable advantage can be re­alized. Results of a brief preliminary analysis indicate that the total wing area of the triform is equal to that used on a cruciform arrangement and that consequently no noticeable change in drag may be realized. In addi­tion, little or no weight saving will be realized, even though one less arrangement or fitting is required be­cause the total load remains the same.

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