Introduction

The Navy Optical Interferometer is a state of the art telescope. It is capable of producing the same results as the Hubble space telescope and costs only $20,000,000.00 US. That means it is ten times cheaper than the Hubble space telescope. This one of a kind interferometer is being built at the Naval Observatory on Anderson Mesa.

The basic concept involves a series of three mirrors working in conjunction to capture an image. With the combined information from the three mirrors a very high-resolution image can be obtained. Below, in Fig. 1, is an over head picture of the optical interferometer.

 
Figure 1

 
A series of mirrors used to reflect the light captured by the interferometer are enclosed and protected in large cans called periscope cans which can weigh up to 1 ton. During construction and maintenance these cans need to be lifted and moved.

The objective is to design and build a crane device that can accomplish this task within the confines of a highly constrained room. A system to move these cans must be designed before this $20,000,000 project can proceed. Shown below is a picture of the cans inside of the room (Fig. 2).

Figure 2

 
As you can see, this room is very crowded giving the lifting design little room to operate within. Also in the picture you can see the old crane which is insufficient to accomplish the task at hand. Once new pipes are installed during construction (shown in figure 3), this old crane will be completely disabled.

 

 Requirements The lifting device must be able to access all six periscope cans within the room and move them to a reasonable working area. The working area was specified by the client and is shown in figure three. The maximum lifting capacity was set at one ton, and the client required a design safety factor of two. The project had to stay within a budget of $15,000 US. The lifting system needed to provide a certain amount of lifting clearance which will be explained below.
 
Figure 3
 
 Lifting Procedure The old periscope cans will have to be removed to install newly designed ones. The lifting procedure for the new periscope cans is shown in the drawing below, Fig. 4.
Figure 4
 
 The new periscope cans consist of lower and upper sections and can be separated during maintenance. Step one in the lifting procedure is to move the can from the can foundation to the working area. Step two is to remove the upper section of the periscope can. During step two the upper section of the can must clear the periscope inside. This process requires the maximum vertical clearance and will be explained further below. Step three is to remove the lower section of the can. Critical Elevation Clearance Figure five shows the critical elevation clearance needed to move and maintain the periscope cans correctly. This leaves the lifting system with 31.44" to operate within.
Figure 5