Blackwood convention Blackwood convention In the partnership card game contract bridge, the Blackwood convention is a popular bidding convention that was developed by Easley Blackwood. It is used to explore the partnership's possession of aces, kings and in some variants, the queen of trumps, to judge more precisely whether slam is likely to be a good contract. Two versions of Blackwood are common: "standard" Blackwood, developed by Easley in 1933, and "Roman Key Card" Blackwood ("RKC" or "RKCB"), named for the Italian team which invented it. Standard Blackwood enables one partner to count partnership aces and kings in general. Key card variants
Atlas E/F upper stage gave the vehicle a payload capacity of to a medium Earth transfer orbit. The SGS upper stage, which consisted of two series-burning solid rocket motors, was used on twelve Atlas E/F launches, with early GPS satellites. The first eight used the SGS-1, which could place of payload into a medium Earth transfer orbit, whereas the last four used the more powerful SGS-2. The eighth launch failed. The Star was used to propel most of the other upper stages used on the Atlas E/F, however it was also used in its own right on several launches. A Star-17A was