A picture of helicopter rotor blades probably won't get very many people
overly excites. However that's not the case with the folks at Eagle
R&D. To us, delivery of these blades means that a whole bunch of HELICYCLE's
will soon be able to take to the air. Tooling up to produce certifies
quality rotor blades for less than we sold then for at Rotorway in the
late 80's had kept our noses to the grindstone.
key quality feature is the 2024-T351 aluminum spar. In days gone by,
2024-T351 spars were simply purchased as extrusions and the price was
reasonable. These days, if by some miracle you could find an extruder
who would sell you a critical part like a rotor blade spar, their price
would give you a heart attack. It's for this reason that most of the
kit helicopter manufacturers now utilize some type of composite blade.
get confused, there are a few kit helicopter blade spars and a lot of
gyrocopter blade spars made from aluminum in the market place. The difference
is these spars are extruded from 6061-T6 aluminum alloy. The centrifugal
force loads on a gyro are lower so 6061-T6 might be used in this instance,
although it is not the best material. To restate, in a powered shaft
rotor, we must use 2024-T351 to meet the 8/1 safety factor required
at the blade root. 6061-T6 does not have a high enough tensile strength
to meet this requirement, given cross-sectional area, airfoil shape,
blade C.G. and overall weight considerations.
key reason for the high cost 2024-T351 is that unlike the 6061-T6, it
is a solution heat treated material. After extruding and preliminary
straightening stretch, a 2 piece die is carefully wired around each
part and it is heated up to 900 degrees F before being quenched in water,
It is then aged prior to delivery. The customer must continue the straightening
process with special tools and press fixtures tailored to his airfoil.
6061-T6 is extruded, stretched and aged, a much simpler process.
order or provide a high quality, yet extremely low cost aluminum rotor,
Eagle R&D had to take an alternative route. We had to find a way to
machine our spars right from the certified quality billet and we had
to do it quickly and inexpensively. In the past, companies like Boeing
Vertol, Bell Helicopters and Eurocopter have machined their rotor blade
spars on huge multi-million dollar planner mills. No one in the kit
helicopter business that we know of has succeeded in this process because
of the time and costs involved. It's taken us months of work, but the
proof of the pudding is in the picture.
issue of quality materials is only one of a multitude on non-compromises
in the HELICYCLE. If forty years of helicopter flying has taught us
one thing, it's that safety has no compromise. In addition, producing
high quality in low volume at low cost is not just an oxymoron, it's
a whole lot of mind bending, back breaking work, We Believe the HELICYCLE
is worth it. !!