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  1. chasbo

    Ducted Fan

    Flying Jeepster: The EAA library has the Hovey book I'm sure, and will fax the relevant pages. I've seen the book advertised in Sport Aviation. Try it there! Chasbo
  2. chasbo

    Pusher Vs Tractor configuration

    Generally, the tractor prop configuration loses less efficiency with its noted deficiencies than the pusher prop configuration with its noted deficiencies. The adverse impact of the fuselage on the quality of the air entering the pusher blade disk is perhaps best evaluated in the Cessna 337, and...
  3. chasbo

    Duct losses

    The loss in static thrust from a 90 degree turn is about 50%. This was obtained by field tests on R/C engines. Throw in two and you'll get about 1/4 what you'd get in a straight through duct.
  4. chasbo

    Popellers CFM

    Your best bet is to get a pitot tube and run a traverse across it to verify your flowrate. You'll get a significant variation across the disk in speed, depending on the design.
  5. chasbo

    Three-Lifting Surface

    Guys: I want to thank you for this very interesting discussion. Based on the discussion, for my jyrodyne, I'm lowering the aspect ratio of the canard to help keep it from stalling before the main lower forward biplane wing, and plan to add drooped tapers to the ends a la Steve Wittman's on his...
  6. chasbo

    Ducted Fan

    To answer Miper: The Hollman equations are for static thrust, and there are a number of simplifying assumptions to get to it. It's a simplified derivation from theory, but assumes a realistic figure of merit for conventional bellmouth designs. Chasbo
  7. chasbo

    Ducted Fan

    There is no easy way to get it accurately. You need to define: static thrust or at what speed do you want the thrust. The inlet lip radius has a huge static thrust effect; does the duct converge,diverge or is it straight? Those also have an effect. Martin Hollman's book on ducted fans gets...
  8. chasbo

    Bellmouth design

    The design of the bellmouth affects its design parameters. One for a jet engine intake is designed differently than one for a ducted fan. There is an inlet section, but ducts with bellmouth entrances also can either have a straight discharge, or can taper inward or outwardly. What do you plan...
  9. chasbo

    basic & detail design

    I think Mogens covered the definitions well. Basic design is about 50% process engineering, with about 50% of the process engineering effort being done there. Detail design involves much more work from the other disciplines.
  10. chasbo

    New Scrubber Design

    Some venture capitalists provide seed money to develop new ideas, but 95% of the time they want patents as the foundation of a new company they fund. They are also expert at taking a much larger share of the eventual proceeds than any inventor feels comfortable sharing for the seed money they get.
  11. chasbo

    How to remove the Ferro oxide (Fe2O3) deposit inside the piping ??

    How about succinic acid solution?
  12. chasbo

    helicopter rotor blades

    Abaris teaches a course in Reno on composite design, and if you look at the syllabus it gives a hint at the complexity one can suffer through to understand composite design well enough to design blades. You also need autoclavable resins to take full advantage of composite capabilities. Room...
  13. chasbo

    Control Surface historical question.

    I've never heard of any aircraft using this, and I've been a pilot and active EAAer for over 30 years. Rutan started the VariEZE with the canard having independent control of the elevators on the canard, to try and use them as elevons to avoid having to put ailerons on the main wing. He didn't...
  14. chasbo

    Multi-element high lift wing fr steep descent

    Check out Zenith Air's webpage, I think zenithair.com. Their 701 has leading edge slats, and interesting info on why you want to use flaperons hanging down below the wing instead of big flaps. (Boundary layer separation on aileron control at low airspeeds......... ) Also really fat airfoils are...
  15. chasbo

    CFD packages

    I've tried a few of the more inexpensive CFD programs for airfoil/wing work, and my opinion is they aren't there yet. Klugy, non-user friendly, and questionable results has been my experience so far. If you're serious, talk to Fluent.
  16. chasbo

    Canard-wing configuration?

    I recommend you get a copy of Andy Lennon's book on R/C aircraft, which covers canards and has some canard designs in it. He teaches that you have to be careful selecting the zero lift angle of attack of the canard and main airfoil differently to have stable flight in pitch. This generally means...

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