Hi, I'm a UT Mech E student about to graduate who's been tooling around with with some helicopter dynamics books for home machined RC contrarotating helicopter fun and I had some questions for any aerospace pros lurking around here. Being ME I know few aerospace guys so I've got some burning questions. I'm machining everything other than the glow motors (.40 in^2 that deliver .92kW @ 15,000rpm) and the RC electronics gear of course. I've got a couple courses in fluid mechanics under my belt and just started tearing up a helicopter dynamics book a few weeks ago but it is all leaving quite a bit to be desired. I am trying to quantify all this theory and gain a bit of intuition as to the working of these ungainly equations I've been using, but I think I'm mixing everything up or something.(adsbygoogle = window.adsbygoogle || []).push({});

the following is mostly concerning hover

I understand that the in the case of the rotor:

-the rotor is like an airplane wing in rotation (over simplified of course)

-thus we need to be concerned with the difference in velocity as we move out to the ends of the radius of the "wing"

-additionally because the blade area is essentially in a fixed position in hover there is something called induced velocity (i hope that is right) which is the velocity imparted to the air by the rotor to essentially move it out of the way (from momentum theory?)

Now if I were to use Blade element theory and momentum theory ( and the formulas associated ) what kind of approximation would the numbers generate compared to the real conditions for something RC sized? Like what percent error compared with reality. I am trying to figure out what torque increase at rpm cost is best given a feasible amount of lift.

How much lift can I actually generate with this motor?

It gets all jarbled up when I look at the math because Lift and Drag increase as rpm (disregarding pitch at the moment). Drag is the source of my torque loading. Thus I need to strike a balance between lift (thus rpm, radius, pitch; disregarding camber) and torque consumption.

All the theory makes sense; I think I just need some way to systematically look at the design of this rotor given my one given; glow motor: .92kW, 15,000rpm A bit of guidance would be much appreciated. Guidance being the key after that jumble I wrote up there lol. I guess it's just hard using theory I've literally just acquired and haven't gone through the whole solve lots of problems for practice student rigamorol and frustrated because this kind of research and immediate application is what I feel like I should have been taught in addition to all this theory in school.

I'll post more tomorrow and look forward to responses as it's late and I got early class :P

Edit: I'm just really interested in the best way to solve this problem through personal study etc rather than taking a class in it. Learning how to do research properly myself and all that.

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# Aerospace Rotor Dynamics Quantification HELP!

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