Coaxial Rotor Blades?

[seawolfxix]

For our senior design project, we're building some sort of personal helicopter with coaxial rotors. While doing a little bit of research at the hobby shop, we noticed that all of the blades were designed to spin in one specific direction. For our coaxial design, we're going to need one set of air foils that are designed to spin in one direction, and another set that are designed to spin in the other direction.

This might be a dumb question, but does anybody make these? Where can I find them?

Our desired blade length is somewhere around 300 - 400 mm.

[Creaky Cactus]

Standard blades have symmetrical airfoils. Most people spin them clockwise (looking down at the heli) so the manufacturers make "top" of the blades "pretty" with the manufacturer's logos etc. There is no reason why you couldn't set up a heli (electric heli) to rotate CCW with the blades installed "upside down". Because the airfoils are symmetric, RC Helis can fly inverted with no problems.

You can get as much advice (some of it conflicting) as you want here (in these forums) and we would be thrilled to help you and see your progress. There are some very knowledgable and helpful guys here.

The Cactus

[seanh]

are you looking at fixed pitch or CP? The FP will need to have pitch built into them while the CP can be symetrical or flat bottom....guessing you won't be doing any inverted flight.

as to how to make them? I know there are people who make their own blades here. If I can find them I'll see if I can get them to respond.