ESDU 80020
Average downwash at the tailplane at low angles of attack and subsonic speeds.
Abstract:
ESDU 80020 contains a simple method for estimating the average downwash angle at the tailplane for subsonic speeds and low angles of attack where the lift, pitching moment and downwash characteristics are linear, i.e. where the flow is wholly attached. The method, which is semiempirical, is a first order one allowing for the major effects of wing planform, body, wingbody interference and tailplane height. Moderate amounts of wing twist are acceptable in the method. The method applies only to wingbodytail combinations although some assessment of the effect of rearfuselage mounted nacelles is given. A computer program of the method is provided as ESDUpac A8020. ESDU 97021 provides a method for estimating the effect of flap deployment on the average downwash angle at the tailplane low speeds.Indexed under:
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Data Item ESDU 80020  

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ESDUpac A8020 
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This Data Item contains 26 interactive graph(s) as listed below.
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Figure 1a  Downwash parameter at an infinite distance downstream. λ = 0 
Figure 1b  Downwash parameter at an infinite distance downstream. λ = 0.25 
Figure 1c  Downwash parameter at an infinite distance downstream. λ = 0.5 
Figure 1d  Downwash parameter at an infinite distance downstream. λ = 1.0 
Figure 2  Downwash parameter for elliptical loading 
Figure 3  Correction to downwash parameter 
Figure 4a  Factor for average downwash across tailplane: A tan Λ_{1/2} = 0. λ = 0 
Figure 4b  Factor for average downwash across tailplane: A tan Λ_{1/2} = 0. λ = 0.25 
Figure 4c  Factor for average downwash across tailplane: A tan Λ_{1/2} = 0. λ = 0.5 
Figure 4d  Factor for average downwash across tailplane: A tan Λ_{1/2} = 0. λ = 1.0 
Figure 5a  Factor for average downwash across tailplane: A tan Λ_{1/2} = 2. λ = 0 
Figure 5b  Factor for average downwash across tailplane: A tan Λ_{1/2} = 2. λ = 0.25 
Figure 5c  Factor for average downwash across tailplane: A tan Λ_{1/2} = 2. λ = 0.5 
Figure 5d  Factor for average downwash across tailplane: A tan Λ_{1/2} = 2. λ = 1.0 
Figure 6a  Factor for average downwash across tailplane: A tan Λ_{1/2} = 4. λ = 0 
Figure 6b  Factor for average downwash across tailplane: A tan Λ_{1/2} = 4. λ = 0.25 
Figure 6c  Factor for average downwash across tailplane: A tan Λ_{1/2} = 4. λ = 0.5 
Figure 6d  Factor for average downwash across tailplane: A tan Λ_{1/2} = 4. λ = 1.0 
Figure 7a  Factor for average downwash across tailplane: A tan Λ_{1/2} = 6. λ = 0 
Figure 7b  Factor for average downwash across tailplane: A tan Λ_{1/2} = 6. λ = 0.25 
Figure 7c  Factor for average downwash across tailplane: A tan Λ_{1/2} = 6. λ = 0.5 
Figure 7d  Factor for average downwash across tailplane: A tan Λ_{1/2} = 6. λ = 1.0 
Figure 8  Effect of body 
Figure 9  Effect on tailplane height 
Figure 10  Downwash at zero lift 
Figure 11  Mach number effect 