By Graham Warwick
Boeing has completed wind tunnel tests of a new rotor blade for the CH-47F Chinook that is designed to generate 2,000 lb. more lift without degrading the heavy-lift-helicopter’s forward-flight performance.
Results of scale-model tests of the latest blade configuration are “promising,” says Pat Donnelly, CH-47F/G program manager. “We are seeing the lift we are looking for with little or no degradation in forward flight.”
Increased rotor lift usually comes at the expense of higher drag in forward flight. New airfoil sections and tip shape improve the performance of the new blade, Donnelly says.
The new swept dihedral-anhedral blade tip is similar to that developed for the canceled Boeing/Sikorsky RAH-66 Comanche scout/attack helicopter, Donnelly says.
Where the current design uses two airfoil sections, for the main blade and tip, the new blade has three, two of them first used on the Comanche and experimental Boeing 360, he says.
Having completed wind tunnel testing of the final configuration, Boeing will now produce several full-sized blades for dynamic and fatigue testing, Donnelly says. Flight tests are scheduled for 2014 and the new blade is planned to be retrofitted to in-service CH-47Fs and MH-47Gs and become standard on new-production Chinooks.
Boeing also has completed testing of an upgraded digital advanced flight control system (Dafcs) for U.S. Army special operations MH-47Gs. The Dafcs was developed for the CH-47F and the upgrade adds such features as control laws for inflight refueling.
The “fat tank” MH-47G has slightly different inertia characteristics to the “skinny tank” CH-47F, Donnelly says, but some of the new Dafcs features will be available for international Chinook customers.
Donnelly says Boeing and the Army’s program office are looking at features, including an embedded-roller cargo-handling system, that could be incorporated into the CH-47F under a second multi-year procurement.
The configuration will be finalized in June 2011 for deliveries beginning in 2014, although the multi-year – planned to cover five annual production lots – is far from certain because of funding constraints, he says.