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  • Users: PaulPounds
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  1. PaulPounds

    Pure teetering rotors - associated problems

    Greetings all, I'm developing a UAV helicopter with a special construction that puts the centre of gravity on the plane of the rotor. This allows me to eliminate torques due to the H-force and horizontal component of the tilted thrust vector. I'd like to make it a pure teetering rotor...
  2. PaulPounds

    Rotor speed dynamics

    Greetings all, My latest work has involved finding the speed response of my aeroelastic rotors when a step is applied to the motor current. Because my robot heli is so small, we change thrust by varying rotor speed. What's more, we change attitude by producing torques by varying the...
  3. PaulPounds

    Hub Springs

    Greetings all, I recently ran across the section on hub springs at the Synchrolite page: http://www.synchrolite.com/1230.html I too looked into hub springs for my four rotor helicopter (though I didn't know anyone else was working on them at the time). I was using the springs to...
  4. PaulPounds

    Dynamic inflow speed

    Greetings all, Here's a problem I've been working on for a bit - what do people know about the rate of change of the inflow through a rotor? I have a weird case where I'm slowing down electric motors that directly drive my rotors. These are fixed pitch blades, so changing the...
  5. PaulPounds

    Someone was interested in aeroelastic model simulation code...

    Greetings, A while ago, some people expressed interest in the aeroelastic blade simulator I was coding for my rotor design work. I've spoken to my supervisor about it and it's ok to distribute it. If people still want it, I'll tidy it up and put it in a form that folks can use. It's...
  6. PaulPounds

    Rotor ground effect oscillations and control

    Greetings all! It's been a long time since I've had a chance to check out the forum, so I need to catch up. While I'm going through the archives, here's my question du jour: I have a rotor that is a drive unit for this four-rotor robot I'm constructing. To design the attitude...
  7. PaulPounds

    Flat plate airfoil polars for stall

    Everyone knows about flat plate airfoils, but no one would ever use one, right? Well, I've got a very thin airfoil rotor operating at high AoA, so I reckon it's performance can't be far off a flat plate at and past stall. Can anyone direct me to accurate polars of flat plate behaviour at stall...
  8. PaulPounds

    Aeroelasticity... counteracting blade twist

    Here's something topical for those following some of the work being done in aeroelsticity. The rotors I've been working on for my robot helicopter are tremendously thin and seem to be twisting something awful. I've put together a computer simulation of the blade-twist/rotor speed system and it...
  9. PaulPounds

    Reverse flow-symetric airfoils

    Greetings all, Ever since seeing that CRW 'Dragonfly' (by Boeing, I think) in the tip-jet thread, I've been thinking about reverse-flow airfoils. These sorts chord-symetric aifoils might be what you'd use in a stopped-rotor VTOL craft like the Dragonfly. By chord-symetric, I mean that...
  10. PaulPounds

    Rotor Blade Torsional Stiffness - Xfoil

    Greetings all, The rotors I have been working on for the past little while seem to be suffering from torsional twist due to large Cm vs. very thin section. The question I need to answer, though, is just -how much- are they twisting. I've writen a Matlab program that calculates blade...
  11. PaulPounds

    Local induced velocity distortion factor

    Greetings all, I'm looking for a way of relating the local induced velocity distortion factor to speed, with an emphasis on low speed flight. Prouty's 'Helicopter Performance, Stability and Control' gives v_L = v_1(1+K*cos(phi)) and then sets K = 1 for speeds above 100 knots, K = 0...

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