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Showroom High velocity / High speed wind generator.

Discussion in 'DIY peripherals' started by T R Para, Nov 21, 2020.

  1. T R Para

    T R Para i make stuff up Gold Contributor

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    I have been working on my wind generator and would like to share my set-up.
    My other hobby is R/C airplanes and I just have a love for anything aviation.

    This system may seem a bit extreme but I had most of the components laying around in boxes just waiting for a good project..
    I am very happy with the final results. It may seem a bit odd using it on a flight sim and your right, but I also am using it for the NL2 rollercoaster sim and it adds a lot to the sense of speed.

    The setup consists of a 90mm ducted fan system (90mm is the dia. of the blades)
    There is the fan, the electric brushless motor and the electronic speed controller aka. (ESC).
    An Arduino Uno is the interface and generates the needed PWM signal to operate the ESC.
    This fan setup uses 24vdc at up to 63 amps which is about 1500 watts.
    The output of the fan is run through 10 meters of 100mm plastic duct .

    This allows remote location of the fan unit (for noise) and lowers the efflux speed of the air ..

    The advantage of the 90mm fan is its rapid spool up / spool down time..
    1500 watts is a lot of power and the fan can output 4.5kg of thrust at 190km/h.

    The long duct work does mellow the speed a bunch but the response time is still there.
    The arduino sketch works with the PT Mover software only.

    I have included the the settings I use on both FS2020 and NL2.
    The sketch may work with digital mechanical servos but will most likely burnout analog mechanical servos (frame rate is too high).
    It is compatible with all electronic speed controllers that I am aware of..

    The Ducted Fan setup can be expensive if purchased new but used setups run under $100 on such forums as R/C groups classified. They are plentiful since often the fan unit is the only surviving component of todays very popular Almost Ready to Fly foam model jets....
    Link to used fans
    https://www.rcgroups.com/aircraft-electric-jets-fs-w-380/

    The video below is a quick example of of the fan units spool up speed and its tracking to the sims speed. The sound is that of the Fan unit and not the sim. The sim audio has been muted.
    The included pics are the "direct output" screens in PT Mover and is meant to be a starting point for those working on the project.
    The sketch is a slightly modified rendition of the original PT Mover sketch.
    Again this is only compatible with Pt Mover and verified with Version 3.33 .

    Attached Files:

    • Winner Winner x 2
    Last edited: Nov 21, 2020
  2. Ads Master

    Ads Master

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  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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  4. RacingMat

    RacingMat Well-Known Member Gold Contributor

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    Nicely done! Thanks for sharing :)
    This fan is a huge hungry beast 63A @24VDC!!!

    I'm just wondering why the fan speed up or down by levels and not continuously... is it a limitation of the fan ESC? It would be more immersive with a continuous ramping.
  5. Zed

    Zed VR Simming w/Index Gold Contributor

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    It’s hard to say from the video but sound pressure levels might need a check to make sure they aren’t dangerous. I’ve been around ducted fans and they can be very loud. Shouldn’t be too bad with sealing headphones, but open style headphones or VR headsets with floating speakers like the Index or G2 will let that in. Obviously it’s hard to tell if this is an issue from a video but it’s a work habit. Used to have to deal with sound pressure checks in loud environments for worker safety/health requirements. Just asking.

    Also, I tried the flexible ducting for my wind installation and it dramatically reduces airflow. Very convenient and flexible but terrible for air volume especially if not stretched to a more uniform ID. Smooth wall plastic fittings with uniform or smoothly-transitioning IDs flow much much better than that flexible hosing. I found 4” diameter plastic street ells and tubing that are light weight and easy to use worked much better.

    And I agree with Matt. I bet those steps could be from how the fans are being controlled. Might be dropping a few bits somewhere in the PWM code leading to the stair steps. ESCs for motors generally are good to at least 8 bits /255 steps last I worked with them. The ones I used were meant to plug in like R/C servos and I could never discern the steps. If you can try a servo, I'd be curious if you see a steppy output there too.

    Excellent work, though. Never even thought about ducted fans from R/C aircraft. I bet they really put out some air. Great for open cockpit racing or flying!
  6. T R Para

    T R Para i make stuff up Gold Contributor

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    @RacingMat @Zed Thanks for your comments folks. It makes for a more interesting discussion.
    Mat, you are spot on about the RPM steps. They are being caused by the pulse-width stepping.
    I can see it in the scope.

    If you look at @pmvcda sketch you will see he does not use the typical Servo.h library.

    He just writes his own code and it is set for the typical "Boxer" fans that use a really fast frame rate.
    The sketch is way beyond my pay grade.. But I hacked around with it and got it the best I could.
    If you use SimTools/Game dash the sketch it uses is the Servo.h library and is smoother.

    And Zed you are correct about the high noise levels. I normally only sim with Vr HMD Reverb G1 that blocks out the fan noise. I actually had the G2 here for a few days and I ended up adding foam ear cups to block the noise. Unfortunately the G2 quit working after 3 days and I sent it back for a refund. The improvement was there over the G1 but not $670 worth to me.

    I am using 10meters of flex hose and actually run the fan in a separate room. The loss of air velocity is definitely noticeable but mounting the ducted fan on the rig would be unbearable both in noise and air pressure / velocity .

    The advantage of the Ducted fan is its lower latency with fast spool up /spool down times .
    And of course the air flow is extremely abundent! lol

    I did hit up @pmvcda about the PWM problem I was having in the sketch but the guy is being hammered in all directions with his PtMover software (which I love!) and he did not need me to add to it.
    His sketch is working pretty good with just one minor change in line 42.

    TCCR0B = TCCR0B & B11111000 | B00000010; // set timer 0 divisor to 8 for PWM frequency of 7812.50 Hz
    Changes to

    TCCR0B = TCCR0B & B11111000 | B00000101; // set timer 0 divisor to 1024 for PWM frequency of 60 Hz.

    Reference::
    https://arduinoinfo.mywikis.net/wiki/Arduino-PWM-Frequency

    Thanks again for your comments :cheers
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    Last edited: Nov 23, 2020
  7. pmvcda

    pmvcda aka FlyPT

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    That code was sent to me by @SilentChill .
    I just adjusted the serial read loop.
    It's using just 8 bits. But think it's enough for wind.
    • Agree Agree x 1