Radar System Engineering

SEC. 9.25] EXAMPLES OF RADOMES 317
will determine whether the problem is one of strength or stability. The
stability problem is a difficult one to meet, since no ribs or other means
of reinforcement can be used for the extensive transparent area because
of possible distortion of the electrical pattern.
The design of the mounting of the radome should have due consideration.
Servicing requirements necessitate removal of the radome. The
means of mounting the radome must be quick-fastening as well as strong.
Just as the final proof of a satisfactory aerodynamical and electrical
design are aerodynamical and electrical tests, so structural tests are
FIc. 9.3S.—A retractable radome (1) partly extended on a B-29, and tbe bulge to accom.
modate tbe r-f unit (2) aft of the radome.
necessary to assure a satisfactory design, for in a streamlined shape the
calculations can at best be only approximate.
9.26. Examples of Radomes.—Types of radomes vary greatly in size,
shape, and method of construction. Attention is called to a few representative
radomes.
Figure 9.38 shows an early type of retractable airborne radome
mounted on a B-29. The radome is a cylinder 3% in. in diameter and
extending about 33 in. when unretracted. While the shape is ideal
electrically, its effect on the speed of the aircraft is most objectionable.
The leading edge of the Eagle vane (Fig. 9“18) is a radome made of
two Fiberglas walls with occasional ribs as spacers. While the airfoil
section is in itself of low drag, the attachment to the plane increases the
drag until it is almost as high as that for the cylindrical radome. This
increase in drag is due to the interference and stagnation points set up by
mounting the airfoil to the plane. An additional feature of this radome
was that it was designed to be deiced by means of hot air. The optimum
wall spacings for heat transfer and for electrical transmission do not
coincide, so that deicing is not very efficient.
A good bombing antenna installation for a B-29 is shown in Fig. 9.39.
This radome houses the antenna shown in Fig. 9.8. The radome extends