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1/20 Scale U-2R (3D Printed)

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  • 1/20 Scale U-2R (3D Printed)

    With the A330-300 finished, time to move on to the next project.

    Specifications:
    Scale: 1/20
    Wingspan: 1600mm
    Length: 960mm
    Wing Area: 23.7 dm^2
    Powerplant: XRP 50mm (11 blade) with 4200kV motor


    Hoping to keep the build under 1000g with a 3S setup. TWR would be about 0.48 on 3S, and 0.64 with a 4s (1200g AUW). Super Pods will be removeable, and I might even try to make simple retracting gear using mechanical retracts.

    My order of 50mm XRP fans got delivered this week, so now I can do final measurements and get the ducting completed. I may print a pair, one in white for the NASA scheme, and the second one in black.

  • #2
    Originally posted by Dirty Dee View Post
    With the A330-300 finished, time to move on to the next project.

    Specifications:
    Scale: 1/20
    Wingspan: 1600mm
    Length: 960mm
    Wing Area: 23.7 dm^2
    Powerplant: XRP 50mm (11 blade) with 4200kV motor


    Hoping to keep the build under 1000g with a 3S setup. TWR would be about 0.48 on 3S, and 0.64 with a 4s (1200g AUW). Super Pods will be removeable, and I might even try to make simple retracting gear using mechanical retracts.

    My order of 50mm XRP fans got delivered this week, so now I can do final measurements and get the ducting completed. I may print a pair, one in white for the NASA scheme, and the second one in black.
    I have the old 64mm from I believe Lanyu, 3s, willfully underpowered. I modified it with inboard flaps and rudder and 2 centerline wheels. Never could get it to take off. Always had to chuck it but, the wheels were great for landing
    Attached Files

    Comment


    • #3
      Cool! I have the Hobby People airframe still. Plan to add gear flaps and a 4S 64mm fan. Where are you getting the airframe from? Is it going to be 3D printed?

      Love your 3D weapons on Thingiverse! Thanks for sharing your designs.

      Originally posted by Dirty Dee View Post
      With the A330-300 finished, time to move on to the next project.

      Specifications:
      Scale: 1/20
      Wingspan: 1600mm
      Length: 960mm
      Wing Area: 23.7 dm^2
      Powerplant: XRP 50mm (11 blade) with 4200kV motor


      Hoping to keep the build under 1000g with a 3S setup. TWR would be about 0.48 on 3S, and 0.64 with a 4s (1200g AUW). Super Pods will be removeable, and I might even try to make simple retracting gear using mechanical retracts.

      My order of 50mm XRP fans got delivered this week, so now I can do final measurements and get the ducting completed. I may print a pair, one in white for the NASA scheme, and the second one in black.

      Comment


      • #4
        Phantom cool, is the lanyu the same as the hobby people/Phase3 airframe? I always thought it was interesting that the wings were held on with friction only, no screws.

        vduniec This is a design I am modeling on the computer and preparing for 3D printing in ABS. Glad you are enjoying the free files i have on thingiverse.

        Comment


        • #5
          Originally posted by Dirty Dee View Post
          Phantom cool, is the lanyu the same as the hobby people/Phase3 airframe? I always thought it was interesting that the wings were held on with friction only, no screws.

          vduniec This is a design I am modeling on the computer and preparing for 3D printing in ABS. Glad you are enjoying the free files i have on thingiverse.
          You are correct it is the Phase3 airframe, I couldn't for the life of me remember, and didn't feel the motivation to Google it. I never liked the "friction lock", and therefore glued my wings on prior to her maiden. I have a van so size isn't an issue for me.

          Comment


          • #6
            I'm thinking a single 4-6mm carbon tube spar for mine, and some forward/rear attachment tabs much like the freewing jets have. I was thinking even doing some kind of "snap lock" thay you just push back in to release the wings, but I might just stick with traditional screws/bolts.

            Finished up the intake ducting and exhaust tube in CAD, intake area is ~95% FSA, so should perform well minus the duct losses due to the long lengths. Worst-case, I might make an optional cheater grate on the top of the fuselage. The intake I may modify to converge into a full tube instead of the donut shape it currently is. Seeing as I will have a wing tube go through the intake, I should have a little more cross-sectional area to counter that. I will also make an aerodynamic fairing to go over the joiner tube to reduce turbulence in front of the fan.

            Comment


            • #7
              Design is close to being finished. Wings just need some tweaks for attachments of the removable super pods. Fuselage tail section is mostly done and I am moving to the EDF and battery bays.

              To avoid having to add nose ballast, I am designing a torque tube for the rudder and elevators so the servos can sit in the battery hatch ahead of the CG.

              wings will have 4mmx2mm carbon tubes to strengthen them, as well as help with aligning the sections together. The vertical stab goes on pretty nicely, but I am still adding a small 40mm CF tube mostly for alignment during assembly.

              Comment


              • #8
                Here is a test print of the tail section. I'm using 3mm square CF tubes to operate the elevators and rudders.

                Comment


                • #9
                  Here is a whole wing with detachable super pods. Some printer setting tweaks and minor design changes and I will be printing the first set of wings.

                  Comment


                  • #10
                    DD, You are a bloody genius. Amazing work. Best, LB
                    I solemnly swear to "over-celebrate" the smallest of victories.
                    ~Lucky B*st*rd~

                    You'll never be good at something unless you're willing to suck at it first.
                    ~Anonymous~

                    AMA#116446

                    Comment


                    • #11
                      Thanks

                      Comment


                      • #12
                        Did a destructive test to make sure the wings and annular spar former can survive high G maneuvers. Plane was balanced on the MAC points, and handled 9.25kg of load.

                        At 9.85kG, the port spar started to break and the wing folded in. Assuming 1100g AUW without super pods installed, the plane could handle 8.4G loops. I think if I use wrapped CF tubes instead of pultruded it would be stronger.

                        Comment


                        • #13
                          It is surprisingly easy to exceed 9G

                          Many years ago someone put a G meter in a Pattern Competition model and exceeded the meter's 38 G max reading, just doing the AMA Pattern Master's sequence.

                          Dynamic soaring models have been calculated to exceed 120 G.

                          FF gliders and rubber power since 1966, CL 1970-1990, RC since 1975.

                          current planes from 1/2 oz to 22 lbs

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                          • #14
                            WOW Dee, you never cease to amaze me.

                            Mike
                            \"When Inverted Down Is Up And Up Is Expensive\"

                            Comment


                            • #15
                              So cool and glad to see you efforts into this interesting airframe. I have the Hobby People U-2 that I plan on modifying some day but would like to buy these files from you when they're complete just to support those who improve the hobby.

                              Comment


                              • #16
                                Ya know the really cool thing about Dee is his stuff actually fly's. I've seen many really cool builds that never leave the ground or even get completed. I have to really admire the guy.

                                Mike
                                \"When Inverted Down Is Up And Up Is Expensive\"

                                Comment


                                • #17
                                  Thanks Guys. Hoping to have everything finished in the next 2 weeks, and get it flying before it gets too cold. Probably will strap a mobius cam for some inflight footage.

                                  Comment


                                  • #18
                                    Originally posted by Dirty Dee View Post
                                    Thanks Guys. Hoping to have everything finished in the next 2 weeks, and get it flying before it gets too cold. Probably will strap a mobius cam for some inflight footage.
                                    Anticipation
                                    TiredIron Aviation
                                    Tired Iron Military Vehicles

                                    Comment


                                    • #19
                                      Lead time on some 1mm piano wire and printer issues slowed me down a bit. But still moving along. I was curious about how the glide slope would be, so I made a downsized 1/50 scale chuck glider at 88g balanced to 25% MAC

                                      Did some thrust tests and found that the long intakes and exhaust create 25% thrust losses.

                                      FSA: 1,338 mm^2
                                      Tail Exhaust Area: 1,306mm^2
                                      97.6% FSA

                                      Baseline:
                                      With the EDF mounted in the single section
                                      Grams of Thrust: 500g
                                      Max Amps: 26.4A
                                      Max Watts: 297.5W

                                      Full Exhaust:
                                      Full tail section
                                      Grams of Thrust: 440g
                                      Max Amps: 25A
                                      Max Watts: 283W

                                      12% losses

                                      Complete Intake and Exhaust:
                                      Full inlet and exhaust
                                      Grams of Thrust: 375g
                                      Max Amps: 25.3A
                                      Max Watts: 288W

                                      25% losses

                                      Comment


                                      • #20
                                        Inspiring work as always, Dirty Dee!

                                        Just a thought about the load testing you've mentioned... I noticed the photo of your wing sections shows joints that are perpendicular to the typical wing load. If your wrapped carbon tube doesn't do the trick (I happen to think it will be fine), then perhaps consider using a staggered system where each joint overlaps its neighbor in a layout opposing the Gs. This would help further distribute the load across the wing at the joint positions. I could see an arrangement where, nearer the wing root, the overlapping section opposes the downward force (that snaps wings), and outward toward the tips the overlapping section opposes the upward force (that flexes wings to failure). Of course, this would greatly complicate the 3D printing process because the base of the section is no longer completely flush to the bed.

                                        And again, I think it's overkill. But I thought I'd mention it nonetheless.
                                        Live Q&A every Tuesday and Friday at 9pm EST on my Twitch Livestream

                                        Live chat with me and other RC Nuts on my Discord

                                        Camp my Instagram @Alpha.Makes

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