DESIGN: AeroVantage - Transition Mechanism - Proposed Methods - Pivoting Arms #2
- NO GOOD. THE DISK IS TILTED BACKWARD WHEN THE X-SHAFT HAS ROTATED 150-DEG FROM CRUISE. See 1640.html
- THERE IS NOTHING (YET) TO STOP OVER TRAVEL ON THE FORWARD ARM WHEN IN THE HOVER POSITION.
Pros & Cons:
Only one actuator is required to drive both mechanisms.
The thrust of the forward and the rear proprotors will have a canceling effect resulting in a much lower power requirement for the actuator.
- The ratio of extended length to contracted length is not as much as desired.
This drawing must be updated as per the scale model one (reorient the props)
Currently, the gaps are; Cruise = 152.4". Hover = 85.0". Difference = 67.4"
The mechanism is mounted on an X-spar that runs from the port transition mechanism to the starboard mechanism.
Each of the two mechanisms consists of
At the end of the forward arms is the forward motor and PropRotor.
At the end of the aft arms is the aft motor and Proprotor.
The motors and PropRotors are rotated 90º. This is done by a separate smaller rod, or pair of rods, that joins the motor and the main arm. This smaller rod maybe located inside the forward arm. The ratio on movement between the motor and the main arm is 2:1 and the angle of the outer minor arms will play no roll in these angles.
In other words the rotational movement of the four wrists is 1/2 the rotational movement of the four elbows.
The whole assemblage (port and starboard mechanisms) are driven by one servo in the fuselage or wing root.
The forward and rear are round or rectangular tubing, which slide lengthwise inside rotateable linear sliding guides.
- Two main arms that rotates 180º with the X-spar.
- Two forward arms that rotates 180º about the front end of the main arm.
- Two aft arms that rotates 180º about the rear end of the main arm.
- These two sets of arms exist so that they straddle the motors and thereby give more longitudinal movement.
Description of Operation:
The rotation of the X-shaft (sholders) by 180º fully extends or retracts the proprotors.
Arm-major rotates 190º
Longitudinal Moment in Hover:
Total weight = 1325 lb.
Total disk area = (34.1 ft2 + 55.1 ft2) * 2 = 178.4 ft2
Disk Loading = 7.4 lb/ ft2
Forward arm length to 25% of wing's chord; for large disk = 63.2" = 5.3 ft.
Rear arm length to 25% of wing's chord; for small disk = 89.2" = 7.4 ft.
Forward moment = 51.1 ft2 * 2 * 7.4 lb/ ft2 * 5.3 ft = 4,008 ft-lb.
Rear moment = 34.1 ft2 * 2 * 7.4 lb/ ft2 * 7.4 ft = 3,735 ft-lb.
The center of lift is slightly too far forward. Easy to adjust it slightly rearward.
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Last Revised: April 5, 2008
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