MAKE: SynchroLite ~ Rotor - Hub - 3-blade - CVJ & HS - X-outer

Bill of Material 1380

• A 1/4" bolt has a cross-sectional area of 0.0491 in². So a 1/4" AN bolt has a rated tensile strength of (125,000 x 0.0491) = 6,138 lb. And a 1/4"; Grade 8 bolt has a rated tensile strength of (150,000 x 0.0491) = 7,366 lb.
• A 5/16" bolt has a cross-sectional area of 0.0767 in². So a 5/16" AN bolt has a rated tensile strength of (125,000 x 0.0767) = 9,587 lb. And a 5/16"; Grade 8 bolt has a rated tensile strength of (150,000 x 0.0767) = 11,505 lb.
• Tensile strength is the force needed to induce failure along the long axis of the bolt, along the length of the bolt.
• Limit load factor for thrust loads = 4 * (550 GW / 2 masts) = 1,100 lbs. [Factor from ~ MDD p.11]
• Factor for hub spring = 2 * 1,100 = 2,200 lbs. [This is my guesstimate.] Not required with 2-blade teetering rotor.
• Safety factor = 1.5 * 2,200 lbs. = 3,300 lbs. [Factor from ~ MDD p.11]
• Divided over two bolts, located on each side of the lug = 3,300 / 2 = 1,650 lb.
• Additional safety factor allowance with 1/4" AN bolt = 6,138 / 1,650 = 3.7:1 ⁽¹⁾
• (1) Note that if the Hub Spring factor were set at 1.5 then the additional SF allowance would be 4.9:1
• Additional safety factor allowance with 5/16" AN bolt = 9,587 / 1,650 = 5.8:1 ⁽²⁾
• (2) Note that if the Hub Spring factor were set at 1.5 then the additional SF allowance would be 7.7:1

For comparison with Robinson's Factors see; DESIGN: SynchroLite ~ Rotor - Hub - 3-blade CVJ & HS - (CDUJ) - Bearing - Mast - Thrust & Teeter

Back to top | SynchroLite Home Page | UniCopter Home Page | Nemesis Home Page