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  1. Jan Carlsson

    DT6 F1 Racer

    yes I have told Dave my findings in the topic, I did a run on 2, 3, 4 and 5 blades, not a surprice what is best.
  2. Jan Carlsson

    Verner S9 vs Rotec R-3600

    I Think the rotec is a Beautiful Engine, I ones asked them about Horsepower and if they where dyno tested, and questioned the size of propeller they recomended, they told me the Engine was geared (that I know already) and that I didn't understand horse Power, in an aggressiv way. I took my Eyes...
  3. Jan Carlsson

    Prop Sizing and PSRU Gearing

    if the gearbox have a limit of 4500 RPM in, no meaning thinking about 6000 RPM, the propeller will absorb the Power at that RPM, it is not the most efficient diameter for that Power/RPM/speed, hopefully the propeller CL is matched for that low load, and it will be ok.
  4. Jan Carlsson

    Prop Sizing and PSRU Gearing

    And the fixed pitch propeller DEMAND curve, is P=(RPMx/RPMmax)^3 the max Power the propeller will see is where it meet the WOT curve. http://2.bp.blogspot.com/-KGVFN_3ePpw/U-_P2EIiViI/AAAAAAAAA3g/bhXEYoWbWq4/s1600/3JH5e%2Bpower%2Bcurve.jpg here is a good Picture of a Engine, Before and after...
  5. Jan Carlsson

    Prop Sizing and PSRU Gearing

    If you drive you car at say 50 mph, you don't use full throttle, then come to a steep hill, and need full throttle to hold 50 MPH, RPM is in both cases the same, say 2000 rpm, same gear, it is only when you put the fot down fully that you reach that published curve. at that RPM, on the other...
  6. Jan Carlsson

    Prop Sizing and PSRU Gearing

    Answer is if you are not at WOT you are not on that Power curve published by the Engine maker.
  7. Jan Carlsson

    Prop Sizing and PSRU Gearing

    But there is no magic behind those numbers, can't calculate a propeller based on tip speed or slip, propeller slip as Little as wings do, with the correct diameter and blade area there is very Little diff between pitch and effectiv pitch, that is often the result but not a given horse.
  8. Jan Carlsson

    Icon A5 Update - No Deliveries!?!

    Thats the formula for climb rate, maybe I missed something previus in this thread
  9. Jan Carlsson

    Prop Sizing and PSRU Gearing

    Not behind the propeller :)
  10. Jan Carlsson

    Prop Sizing and PSRU Gearing

    it is as Ross say, there is no magic number of tipspeed, it depends on Power and speed, number of blades and RPM, in many cases the resulting propeller is smaller or have a lower rpm for its length.
  11. Jan Carlsson

    Please Help to Understand

    looking at the Pictures in OP, I say it is a good start to understand what a propeller do, but there is more to it when you have a fuselage on one or the other side of the propeller. far behind the propeller the air have increased in speed by not so Little, half of that increase will be at the...
  12. Jan Carlsson

    Please Help to Understand

    There is no Theory in propeller design, it is all black magic :)
  13. Jan Carlsson

    Prop Sizing and PSRU Gearing

    If the gear ratio is free, it come to the size possible to fit, find the nearest gearing ratio to give that RPM and Size, then calculate the propeller.
  14. Jan Carlsson

    New Community Amphibious LSA VAL-31 "Aquarius" a non commercial project

    I realy like the look of this sea plane, would it not be a good idea to make a very good plug and mold from start if you are planing to sell hulls or kits? uneven wrinkeled hull skin will not tell the potential buyers that this plane is well built, even if strong enough and good aerodynamicly.
  15. Jan Carlsson

    Tip tanks

    The Polliwagen had wing tip tanks.
  16. Jan Carlsson

    Increasing radius wing root fairings

    saw something about 10% of the chord, and expanding, I see that as 10% radius of the local chord, so mid chord it is 5% of the total chord length.
  17. Jan Carlsson

    Jabiru 3300 experience, comments

    You work with Santa? :)
  18. Jan Carlsson

    Best Prop Tip Speed?

    Thank you Pete. it is a Little bit different in real World with 3D airstream, that seems to delay the influence of the speed of sound, from what these 2D flow show.
  19. Jan Carlsson

    PSRU for Range Rover engine??

    looks like it just have balistic CAD renderings not actual photo
  20. Jan Carlsson

    Random electric motor questions

    I checked some electic motors for a motor sailor, (boat) 5-10 kW and there about, the brushless was described as programable or 50 RPM per volt often max 5000 rpm. DC motors often volt/rpm regulated, the Lynch motor have some different setup, but 45 or so RPM per volt. depending on the controler...
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