14.02.2013 Views

Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Chapter 6 / Missile Guidance<br />

_ _<br />

tracking bandwidth of 0.5 Hz. Figure 6-9 shows that the miss distance drops<br />

from 0.24 m/(m/s 2 ) to 0.01 m/(m/s 2 ). The improvement obtained increases<br />

with decreasing weave frequency. Increasing the tracking bandwidth to<br />

2 Hz reduces the miss distance by a further 10 dB.<br />

MISS DISTANCE/UNIT TARGET LATAX ( DB )<br />

MISS DISTANCE/UNIT TARGET LATAX ( DB )<br />

20<br />

10<br />

0<br />

-10<br />

-20<br />

-30<br />

-40<br />

10 -1<br />

20<br />

10<br />

0<br />

-10<br />

-20<br />

-30<br />

-40<br />

10 -1<br />

WW = 0.25 HZ<br />

6-27<br />

10 0<br />

FREQUENCY ( HZ )<br />

WE = 0.5 HZ<br />

WW = 1 HZ<br />

WW = 0.5 HZ<br />

Tracking Bandwidth := 0.5 Hz<br />

WW = 1 HZ<br />

WW = 0.5 HZ<br />

WW = 0.25 HZ<br />

10 0<br />

FREQUENCY ( HZ )<br />

WE = 2 HZ<br />

Tracking Bandwidth := 2 Hz<br />

Figure 6-9 : CLOS Miss Distance with Weave Tuning<br />

This performance requires accurate weave frequency estimates. A simple<br />

expression for the accuracy required to achieve a particular miss distance<br />

provided by Vorley [V.3] is,<br />

∆ω<br />

ω<br />

W<br />

W<br />

: =<br />

2<br />

W<br />

ω ⋅ ∆<br />

π ⋅ &P<br />

&<br />

rT<br />

Pt<br />

rT<br />

t<br />

Equation 6.6-13<br />

Typically, for a weave frequency of 0.25 Hz, target acceleration of 10 g, and<br />

a miss of 4 m the fractional error is 0.02. This analysis is only a guide to the

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!