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NASA Prandtl-D Flying wing

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    NASA Prandtl-D Flying wing

    Following the suggestion of our fellow member my77gmc I´ve designed for 3d printing the NASA Prandtl-D flying wing:

    And this is where the idea came from:

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    Will make it glider only and post files on thingiverse.

    My model will be 2.4 meter span, probably printable on a Prusa i3, 250X210X200 the chord at root its only 230mm plus a little bit because the wing is swept back.

    Half wing printed, 225 grams!

    final AUW should be around 450+2 servos+receiver+1 small bec and one 2s 700mA battery+some lead? 600 grams perhaps.

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    Attached Files


      Left half of the wing printed:
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ID:	649 First prototype printed, will do some free flight tests and find the cog.


          May I suggest ailerons and servos are unnecessary.
          Two very small motors, controlled differentially, may provide enough thrust to engage proverse roll.
          Enough thrust to climb to 100 feet in 60 seconds.
          Battery sized for 4 minutes acquire flight experience.


            humm... this wing design provides proverse yaw already, I have never flown it but I suspect that with more action on the elevons the wing will roll.

            Putting motors on the tips could be an interesting experience, have you seen it before on a flying wing?



              or even very small fans.



                Right. I was imagining the motors at the tips like the cl-400

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                I think the kind of control you get with motors is not comparable to elevons, you could fly and control on a very quiet flight but just landing that way would be problematic.


                  The Air Hogs PowerHawk twin electric bi-plane has a non-functioning propeller on the nose.

                  Two pusher propellers provide the thrust: half throttle for straight and level, full throttle for climb.

                  Bank left by reducing power on one motor and increasing power on the other motor.

                  I enjoy entering a stable bank of five feet radius, kinda / sorta as if flying on control lines around me.

                  This is why I suggest ailerons and servos are unnecessary.

                  Two very small motors, controlled differentially, may provide enough thrust to engage proverse roll.

                  Why take the weight out of the wingtip?

                  The moment of inertia of the servo plus wiring degrades the proverse roll induced by the forward leaning lift vector of the wingtip.

                  Glider guiders know from experience to build the lightest outer wingtip panel possible, to be able to better read the air.

                  So move the servo plus wiring inboard closer to the centerline of the wing,

                  Then make a paradigm shift by taking the motor out of the servo, and using it to turn a propeller or fan for thrust.

                  50 watts per pound will easily fly this efficient flying wing.

                  With two 50 watt motors, controlled differentially, mounted on pylons above the wing, the 3d printed NASA Prandtl-D flying wing should fly well like the PowerHawk.


                  Image result for air hogs powerhawk


                    "I had a spare Warp4 motor and an APC 6x4 electric prop. Input power is 125W."
                    Derate to 50W!


                    Build Log Minimoa Motor Pod TugBoat
                    Registered User
                    NSW, Australia

                    Joined Jun 2003
                    1,257 Posts


                      You may have a point here. It would be an interesting experiment.

                      Many years ago I played with that air hogs plane you posted, back then it was the smallest receiver and actuator system we could get, we replaced the motors by actuators and it was fun.


                        Anyone venture to guess the Reynolds Number this wing flies at, anyone?

                        Oct 30, 2015, 11:36 AM
                        “Hi Steve,
                        Wing Area =41 ft^2
                        Wing Span = 25 ft
                        GTOW = 31 lb
                        Wing loading = 0.75 lb/ft^2
                        Launch height was 135' Design cruise is .6 CL.
                        No airspeed instrumentation on board this one yet, my guess was about 18 mph.
                        CG is forward, safe for first flight, but you can see I'm carrying up elevator as is passes by.
                        We are going to do a couple flights next week to get some flow vis photos,
                        then it will be brought down and instrumentation installed.

                        Jul 17, 2017, 12:02 PM
                        “The latest 25' span P-3c took to the air this morning for it's maiden flights.
                        This one is all carbon & weighs 32 lbs (12 lbs lead ).
                        It will now be integrated with with it's fiber optic, pressure sensing & air data probe payloads
                        and continue with data flights later this month.”


                          Is it this?


                          The chord at root is 23,5cm, I´m not sure that on a swept wing like this the correct value to use is this.

                          Kinematic viscosity may not be correct, from what I´ve seen for air at 15ºC should be 1.81×105