Rod Nelson, the chief operations engineer at Williams, has admitted that the 2009 season was a 'mixed bag' for the Grove-based outfit after it failed to secure a top six finish in the F1 constructors' championship.

Williams went into the season finale in Abu Dhabi vying for the place with BMW Sauber but lost out to its rivals after failing to score for the fourth time in the final five races of the year.

With BMW picking up four points thanks to a fifth place finish for Nick Heidfeld, the outgoing team pipped Williams to sixth place by just 2.5 points and Nelson admitted there was disappointment at missing out on the position.

“Although the car was competitive at the start of the year, we had some difficult races with accidents in Melbourne and poor weather in Malaysia and Shanghai,” Nelson reflected as he looked back over the 2009 campaign. “The middle of the season saw consistent performances, with eight points-scoring races in succession. The consistency faltered somewhat with a poor performance at Monza's low downforce Autodromo, followed by a pitlane penalty at Singapore which robbed us of a good podium finish.

“We were once again looking likely for a podium finish at Brazil had it not have been for the gearbox failure, and we finished just out of the points at Abu Dhabi meaning we were unable to defend our position in the Constructors' Championship.”

With Nico Rosberg and Kazuki Nakajima both leaving the team, Williams will field a new look line-up in 2010 with Rubens Barrichello and Nico Hulkenberg coming in as replacements, and Nelson said work was progressing well on the FW32 that the pair will use next season.

Hulkenberg meanwhile is set to make his first test outing since his confirmation in the young driver tests at Jerez next month.

“The design, development and manufacture process of the new car is well under way now so the entire factory is flat out,” he said. “We have the three-day young driver test that the FIA allows us in December during which we will be testing Andy Soucek following his victory of the inaugural F2 Championship, together with our new race driver, Nico Hulkenberg. The FW32 will be ready to run at the start of the February testing period.”