Introduction:
The
DreherAero Scull has been in development for nearly two years and is a totally new oar for 2009. The
Aero is a truly revolutionary oar with regard to the design, manufacturing processes, and even the type of carbon used. It is a radical departure from current oar production methods. The result is the first oar that attempts to reduce boat speed decrease due to air resistance of the oar shaft and blade as they both move in the same direction at maximum boat and oar shaft velocity.
The Design:
The Aero draws on 20 years of oar/scull design and carbon prepreg manufacturing experience. The major departure from previous designs is an aerodynamic shaft and hydrodynamic blade system that tests to be more efficient by optimizing the oar shaft and blade shape as they move through the water and the air.
The aerodynamic shaft profile fits exactly into the matching blade profile and assures that the blade pitch exactly matches the sleeve pitch. The result is perfect repeatable pitch, oar to oar. Our manufacturing method allows for a molded in seat for the sleeves that further insures perfect pitch from the sleeve to the "lock & key" blade attachment.
Manufacturing Method:
An aerodynamic shaft profile required a new manufacturing method, to reduce drag on the shaft. The result is a smooth continuous aerodynamic shape. Molding to control the outside shape of the shaft rather than to the inside diameter allows location contours for a sleeve "seat". These contours in the sleeve area are unlike any that are possible on present roll wrapped oars. Sleeve locating contours, designed as an integral part of the tooling, allow the sleeve to be easily installed and when worn, the sleeve can be replaced with no adhesive. No pitch checking is ever required because the sleeve “seat” was integrated in the total oar design.
Hydrodynamic Advantages:
Hydrodynamic theory and racing blade performance models shows a high component of lift propelling force at the catch position. This recommends a high aspect ratio blade shape. When the shaft is 90° to the axis of the boat a bigger area would theoretically be best to maximize the drag type propelling forces that predominate. The last 30° of the drive again trend toward a high aspect ratio shape as lift forces reestablish themselves toward the finish.
Ideally, to optimize the blade size you would require a variable size blade. The Aero blade/shaft system is as close as one can come to a adjustable area blade when the blade is buried deeper at mid-stroke. There the foil section of shaft can act as an extension in blade area to the shaft. The hydrodynamic blade shape seamlessly combined with the aerodynamic shaft results in the water not being able to distinguish where the blade ends and the shaft begins. The blade is exceptionally quiet with little splash at the catch caused by the small profile and seamless transition from blade-to-shaft.
Aerodynamic Advantages:
A true aerodynamic profile seamlessly mated to a hydrodynamic blade profile provides for the ultimate in low wind resistance on the recovery when the boat speed and the oar’s angular velocity are both at their maximum and in the same direction.
The aerodynamic profile is used on the shaft and blade where it will do the most good, toward the end where the angular velocity is the greatest. The aerodynamic profile offers the least resistance at the time when the boat is traveling at it’s fastest – on the recovery, when the oars are out of the water.
Performance:
Less wind resistance on the recovery and improved stability equates to the potential for greater speed for the same effort. The more efficient the sculler and the faster the boat class, the greater the potential for speed improvement.
A side benefit of the aerodynamic shape is a thinner, but much wider shaft where the blade attaches to the shaft, resulting in much more resistance to twist than a circular shaft.
Variable blade area provides the potential for greater speed potential through the water.
Coming Next:
As soon as the sculling oar is in full production, the DreherAero Sweep will fast follow. Reserve your budget for the new DreherAero Sweep!
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DreherAero Sculls on the Drive
Top Drive View Looking from Handle to Blade
Top Feather View Looking from Handle to Blade
Dreher Aero Blades Just Before the Catch
