Warning! This site requires Javascript. Learn how to enable it here.

Ducted Fan -vs- Prop

Discussion in 'Scratchbuild Talk' started by etotheo, Oct 20, 2009.

  1. etotheo

    etotheo Rookie

    Posts:
    11
    Likes:
    0
    Points:
    0
    I have a question for either Dave and or Scott regarding the power plants that there designs revolve around. It seems for the most part that the designs are "jet" based and are driven by a brushless outrunner motor. My question is this, since the designs are mimicking a jet, why not use a ducted fan to try to reproduce the "jet" sound and feel?

    I'm a noob with all things RC... built my glow trainer and now have half a dozen fights under my belt. Found this site last weekend, watched Dave's video's which are great! And now I can't wait to get into e-powered flight.

    Does a ducted fan not just use the same brushless motor, just substitute the prop for an axial fan w/ shrouding?
    Thanks.
  2. cheerIO

    cheerIO Rookie

    Posts:
    16
    Likes:
    1
    Points:
    0
    lysle42 likes this.
  3. Sonicjet

    Sonicjet Rookie

    Posts:
    870
    Likes:
    4
    Points:
    0
    That statement is.... relative.
    For example,you put an 70mm 50amp Edf in an easybuild making 38 oz of thrust, it will not have a slow acceleration.
    Thats my latest project.
    (minus the easybuild..lol)
    Btw an microjet makes ~ 20oz of thrust...:D
  4. all4smallrc

    all4smallrc Airman

    Posts:
    1,057
    Likes:
    11
    Points:
    38
    The differences between edfs and props are pretty simple. A prop has better power at low speed where a ducted fan (edf) will do better at high speed. Just the same, edfs are faster than props in most cases. Props are more efficient believe it or not. To get the same thrust out of an edf as a prop, the edf will be drawing more amps. However, although thrust is the same, the speed of the air coming out of the edf is much faster than that of the prop, allowing the plane you put it in to go faster. Accelleration is also much slower with an edf than a prop.
    lysle42 and callisto like this.
  5. callisto

    callisto Rookie

    Posts:
    11
    Likes:
    11
    Points:
    0
    I came here to ask, I saw, I learned.
    While this hobby seems to be bound by simple subset of the engineering issues that full size aircraft designers deal with, I am often surprised by how much our models are in fact influenced by physical aspects that I previously thought would have a negligible effect.

    TL;DR: Sht is complex. whoa.
    lysle42 likes this.
  6. JettaManDan

    JettaManDan Administrator

    Posts:
    9,151
    Likes:
    1,582
    Points:
    133
    disagree on the EDF is usually faster...especially not ture with a flat foamie.....i have the perfect example..my Prop 2200kv V1 Mig 29 vs my 64MM EDF V1 - The EDF version loses in every speed and power catagory to the prop plane except for cool sound factor...not as much low speed power...about 10mph slower on top end..and it east the same 1800mah battery up in half the time....so for that as a direct comparison the prop plane is better..but the EDF looks and sounds cooler for sure ;) for the rest you are correct....

    if you go bigger with an EDF then sure you can get more speed...but the offset in weight and design means sacrafices in other areas too.
    lysle42 likes this.
  7. csitas

    csitas Cadet

    Posts:
    70
    Likes:
    35
    Points:
    18
    One thing for sure as far as what I see,If you want pure peformance, you don't see any fans. Just look at the 3D guys, also the racers. Those people are put up or shut up types when it comes down to equipment.I'm not saying they are jerks. It's just that they know what goes and what don't.Sound isn't counted.
    lysle42 likes this.
  8. JettaManDan

    JettaManDan Administrator

    Posts:
    9,151
    Likes:
    1,582
    Points:
    133
    yep..highest performance for size and weight is prop for sure...
    lysle42 likes this.
  9. DavePowers

    DavePowers Administrator

    Posts:
    3,366
    Likes:
    1,995
    Points:
    133
    Who let this EDF fan in here..?

    Its true though. EDFs done right are really good, just not as "cost effective" as props.
    lysle42 and Airforce101 like this.
  10. whatmovesyou

    whatmovesyou Ace Pilot

    Posts:
    1,834
    Likes:
    417
    Points:
    83
    As far as EDF speed is concerned, depends on the design (drag). I fly a purchased DF-032 and the speed is about 60+, what my FFF F-22 gets probably in the 50mph with the same 64mm EDF and the weight is within 1 oz of each other.

    It is poor acceleration(especially if one builds heavy and throws poorly) from the EDF's that hinders the builders. If you build lightly and have small clearance between the fan blades and housing, you can launch vertically or off a table at an angle..

    Did this one over 2 years ago.



    This is why I fly them.
Similar Threads
Forum Title Date
Scratchbuild Talk Ducted Fan? Feb 27, 2014
Scratchbuild Talk F-22 or F-35 ?? Ducted Fan Project May 15, 2013
Scratchbuild Talk wow a prop ducted jet Aug 22, 2012
Scratchbuild Talk Ducted fans motor? Jul 2, 2012
Scratchbuild Talk need an A-10 ducted fan Sep 13, 2011
Scratchbuild Talk First edf : Dassault Alpha Fighter 70mm Ducted Fan EPO Plug-n-Fly Jan 20, 2011

Share This Page

string(1) "1"