A055

Group A055

MAKE: SynchroLite - Rotor

Idea: It may be better to not twist the blades. In forward flight the greatest lift comes from the outer portion of the retreating blade. Most of this area is outside the other rotor's disk. In other words, have the greatest downwash for each disk in that area which is outside the area of the downwash from the combined disks. The possibility of blade stall at the outer portion of the retreating blade is not a problem because the forward velocity is limited by FAR 103.

Blade Loading Coefficient [C_T/σ]

See: OTHER: Aerodynamics - General - Blade Loading Coefficient

The 4.75" chord blade is closer to this then the 6.25" chord blade. It would appear that the 4.75" chord blade is definitely the better.

4.75" chord @ 650# of thrust & 3.50º pitch the hp is 44.0 & C_T/σ is .068

6.25" chord @ 650# of thrust & 2.35º pitch the hp is 44.5 & C_T/σ is .052

From Prouty "Helicopter Aerodynamics - p.68" "Most rotors are at the peak of their efficiency in forward flight when C_T/σ is about .08.

The only negative to the narrow chord, so far, is the mention somewhere that a chord should never be less than 5". Has to do with Reynolds Number (proportional to chord times velocity)

Hollmann's Rotor Program November 5, 1999

Re: Blade Mass

I am initially going to assume that the blade, complete with tip weight of 1.5 lbs., has a total weight of 6 lbs. The disk radius is 8.667 feet there fore the weight is 0.5192 lbs/ft and the last element has the tip weight added.

Idea re above note

Use Vortech 0012 5.7 chord blade then later twist it and use it as template for twisted composite 0012 - 5.7

Balance:

Would BCIT be willing to have the rotor balancing done there?

Service Factor:

Email from GR. ~ I asked Sikorsky the service factor they use on rotor parts and it is 1.5.

Fleck Aluminum Blades:

there are some informative postings @ PRA. Search [Fleck blades] & title only. They are in Feb/2000.

Last Revised: December 24, 2003