|
In trying to understand this thread the following questions come to mind. Although Mr. Shannon uses the verb "deploy" is he actually interested in the change in parasitic drag during the gear cycle which would vary throughout its travel or in the steady state condition of down and locked? As we all know drag abruptly increases with door opening, slowly increases further as the wheels/tires rotate to their maximum wetted area then slowly decreases as they reach their vertical alignment then abruptly decreases as the doors close leaving only the residual drag of tires, gear legs, front strut and strut plate. A five knot loss in this configuration seems reasonable. I suspect it is the "steady state" not the "deployment state" that he is concerned with. The second question involves the cross-sectional area of these components in the down position. By rough guesstimation I can't see a projected area of more than say 60 sq. in. per tire and the strut plate plus say 50 sq. in. for the gear legs and for the strut/fork assembly for a total area of 340 sq. in. or 2.4 sq. ft. The third question concerns how the gear door deletion modification affects short field performance. It would seem that there is no difference in the total drag, in takeoff configuration, with or without doors. If anything, I suspect that total drag would actually increase with doors removed due to the disruption of the boundary layer at this location.
|