DC 12m telescope. Preliminary calculations. Investigation of elevation axis position.

Guarino, V. J. ; Physics, High Energy

Argonne National Laboratory

关键词: Cameras;    Moment Of Inertia;    Motors;    Torque;    Computer-Aided Design;   

DOI  :  10.2172/970379
RP-ID  :  ANL-HEP-TR-09-112
RP-ID  :  DE-AC02-06CH11357
RP-ID  :  970379

美国|其它

来源: UNT Digital Library

【 摘 要 】

This paper examines some simple calculations of a 2D model of a telescope in order to understand how different design parameters affect the design. For the design of a telescope it is assumed that they need a design that minimizes deflections of the dish and also minimizes the size of the motors and torques needed to rotate in elevation. A common belief is that a lighter dish and minimum counterweight is desirable. However, these calculations show this is not necessarily true. The torque needed for rotation depends on the moment of inertia and if the telescope is balanced about the elevation axis. A light dish with no CW requires that the elevation axis be several meters in front of the dish (8-9m) in order to be balanced. This is not practical from a structural point of view. If the elevation axis is only 2m in front of the dish and there is no counterweight then the telescope will be unbalanced and the toruqes required will be very high - much higher than the torques needed only to overcome inertia. A heavy dish though can act as its own counterweight and the elevation axis only has to be 2-3m in front of the dish in order to achieve a balanced telescope. Also the struts that support the camera from the dish place a load on the dish which will put a bending moment on the dish. This bending moment will deform the dish and require it to be stiffer. A counterweight structure performs two functions. First, it allows the telescope to be balanced about the elevation axis. Second, it applies a force on the dish that opposes the forces from the camera struts, thereby reducing the bending moment and deformations of the dish.