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

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Chapter 6 / Missile Guidance<br />

_ _<br />

L<br />

6-36<br />

A<br />

ML<br />

t < t ⇒ X : =<br />

0<br />

9<br />

Equation 6.10-6<br />

Thereafter, the state is obtained by integrating acceleration expressed in the<br />

Alignment frame at 4 kHz. Lateral motion is prevented until the missile has<br />

travelled the length of the launcher (LT := 3m). The motion is therefore<br />

dictated by the thrust and drag functions are applicable in the launcher,<br />

( t ≥ t ) ∧ ( P ≤ L )<br />

L<br />

o,<br />

m<br />

T<br />

⇒<br />

P&<br />

&<br />

A<br />

m<br />

: =<br />

T<br />

A<br />

B<br />

⎛ XB<br />

FT<br />

+ F<br />

⋅ ⎜<br />

⎝ mm<br />

XB<br />

D<br />

,<br />

0<br />

,<br />

⎞<br />

0 ⎟<br />

⎠<br />

T<br />

Equation 6.10-7<br />

The gravitational force acts when the missile is clear of the tube. Gravity,<br />

thrust and drag are the only forces modelled until the missile reaches a<br />

stable speed (VS := 80 m/s). Without height droop compensation and noseup<br />

attitude develops and the stable speed was set to prevent incidence<br />

exceeding 5° if the missile is launched horizontally,<br />

&P<br />

&<br />

A<br />

m<br />

: =<br />

( P > L ) ∧ ( P&<br />

< V )<br />

T<br />

o,<br />

m<br />

A<br />

B<br />

T<br />

⎛ XB<br />

FT<br />

+ F<br />

⋅ ⎜<br />

⎝ mm<br />

XB<br />

D<br />

o,<br />

m<br />

,<br />

0<br />

S<br />

,<br />

⇒<br />

⎞<br />

0 ⎟<br />

⎠<br />

T<br />

+ g<br />

A<br />

m<br />

Equation 6.10-8<br />

The fins unlock and roll control is established as the missile clears the tube.<br />

Lateral control is not invoked until the missile reaches its stable speed. At<br />

this point simulator control passes from MS_LAUNCHER in Figure 6-11 to<br />

MS_DYNAMICS in Figure 6-12 when the linear dynamics are,<br />

&P<br />

&<br />

A<br />

m<br />

: =<br />

T<br />

A<br />

B<br />

P&<br />

o,<br />

m<br />

⎛ XB<br />

FT<br />

+ F<br />

⋅ ⎜<br />

⎝ m<br />

XB<br />

D<br />

≥<br />

V<br />

,<br />

S<br />

P&<br />

&<br />

⇒<br />

YB<br />

o,<br />

m<br />

,<br />

P&<br />

&<br />

ZB<br />

o,<br />

m<br />

⎞<br />

⎟<br />

+ T<br />

⎠<br />

A<br />

G<br />

⋅ g<br />

G<br />

m<br />

Equation 6.10-9<br />

The lateral acceleration achieved in response to the STT autopilot demands,<br />

YB ZB<br />

( P&<br />

& , P&<br />

& )<br />

D YB Z<br />

D ZB Y<br />

( ϕ ( A , ζ , ω ) , ϕ ( A , ζ , ω ) )<br />

D2L<br />

LA<br />

o,<br />

m<br />

LA<br />

o,<br />

m<br />

D2L<br />

: =<br />

LA<br />

LA<br />

Equation 6.10-10

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