Scorpion - Dual Rotor Heli

Micro Drone with pivoting Dual Ducted Rotors.

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This project is dead.... oh well

First tests show 2 rotors won't make enough thrust on a single lipo cell.
but 2s is surprisingly powerful.

  • V1 used 6x16mm motors with 55mm 2 blade props.
  • V2 8x20mm motors with 40mm 4 blade props.

both use 2x 3.7g submicro servos.
V2 needed to reduce weight along with improving the hinge for the rotors.
with 2s I think both will fly, as long as the motors don't overheat.

  • V1 I didn't think about the scale enough..weight is about 65g with motors,props and servos.
  • v2 reduced to just 50g with the smaller 4 blade props..but bigger 20mm motors.

Compared to an off the shelf syma s107 heli is only 40.8g ready to fly. with similar size main motors but a geared drive to 150mm props..

I did the design before watching part 2, like I thought they had a new smaller version, but its a quad copter.

The scorpion in the movie has dual counter rotating props so its a quad also...

Bell Boeing V-22 Osprey is real but its more of a Vertical takeoff/landing plane.

banchii lw servo.stl

2x servo mount

Standard Tesselated Geometry - 90.32 kB - 04/26/2023 at 05:34


banchii lw chas.stl

main Frame

Standard Tesselated Geometry - 58.09 kB - 04/26/2023 at 05:34


Standard Tesselated Geometry - 45.98 kB - 04/26/2023 at 05:34


Standard Tesselated Geometry - 27.23 kB - 04/26/2023 at 05:34


Standard Tesselated Geometry - 95.59 kB - 04/26/2023 at 05:34


  • 1 × Arduino micro/nano
  • 1 × Frame Printed Design
  • 1 × nrf or wireless module
  • 2 × 3.7g servo or 9g
  • 2 × Motors Geared motor drawbot?

View all 8 components

  • toroidal​ props, just because i can...

    Saul05/02/2023 at 20:58 0 comments

    • took a try at toroidal props, they really are quiet!
    • not much trust yet. cant even hold their weight.
    • but interesting...
    • real donuts render very slow on my current setup so i'll probably try with a close enough shape..
    • doesn't matter, since 2s seems to be the way to go..

  • Not even close. 2s Tests.

    Saul04/30/2023 at 06:41 0 comments

    None of the other designs have even gotten close to v2.

    But I think the profile i used for v5/6.. will make a decent wing!

    • V2 = 21g @ 4V
    • V6 = 15g @ 4v
    • v2 5v = 36g
    • v6 2s 7.2v = 60g!
    • v2 2s 7.2v = 79g!
    1. Just tested for a couple seconds but almost 4x thrust for double voltage crazy.
    2. Rx with heatsink/ld293d = 14.76g so even with an extra battery it will fly. 
    3. it might even fly with the extra 47g 900mah 2s pack for my rc rockcrawler.
    4. will probably do a tricopter variation soon...

  • CFD.

    Saul04/25/2023 at 01:23 0 comments

    Wanted to figure out what works and why so here I go down the rabbit hole...

    Found the cfd base here. works pretty nice.  

    blender base project

    The results for v2 - v3 are kinda amazing. Real world tests would be fun.. these could basically create a tiny wind tunnel...

  • Duct Design

    Saul04/24/2023 at 11:30 0 comments

    When I started these around the start of the year I just wanted to get a basic pivot design and see what kind of weight it would need to be to fly with some tiny cheap motors.

    Seems like there are some 2s 7.2v 0820 coreless motors. but the set i ordered are 15000kv. so 3.2v rated at 49krpm.

    Anyways I made a simple test stand, realized I could connect a motor module directly.

    1. v1 - Small taper design - 1s lipo = < 6g
    2. v2 - Larger intake taper (about 25%) - same battery = > 21g!
    1. This means for one the duct design is very very important!
    2. basic sanity check means 21g x2 = 40g max excess thrust
    3. so the whole heli should weigh less this for good handling/low batt flying.
    4. The test stand shows each motors thrust - (module weight) since it is balanced.
    • Motor + duct (v2) + prop = 12.85g = 13g. 
    • "Test" electronics about 13.5g
    • battery 11.5g
    • servos about 4g each
    • = 33g + Printed frame. = no flying yet...

    but if v1 -> v2 can get 350% increase maybe I can find another 10g of thrust per motor? 

    guess I will print a ductless motor holder to see what the baseline is...

    While I was waiting for the print I modeled a rocket nozzle from October Sky...

    printed ok but not perfect, sound change but maybe something there...

    Edit: 2 more Duct Variations.

    1. single taper (cone section)
    2. Inlet taper + 2 mm negative taper on h/2
    3. inlet taper + cylindrical middle + 4mm negative outlet taper
    4. inlet taper x2 + Positive outlet taper. (integrated convergent/divergent)

    Theres also variations based on inlet increase vs over taper.

     A1V1 = A2V2

    will probably try to curve the profile as well. im sure that will help when this hardware becomes a plane...

  • Micro 2x Dc Motor + 2x Servo.

    Saul04/21/2023 at 03:01 0 comments

    Pcb with motor breakout made it in a couple days early.

    Clearance is spot on but might want a heatsink. Thinking about pin options.

    Ld293D Motor driver has 2 channels @600ma but takes 4 digis + 2 pwms on the enable pins.

    Its the same ic from the original Motor Shield, not much current but high motor voltage.

    I think I will print a Test stand arm to try to measure thrust and test Steering...

  • More Power.

    Saul04/14/2023 at 08:45 0 comments

    The motor drive board might work, but really its meant for an RC car/truck.

    Most drones use brushless for good reason...

    Since motors are sold in sets of 4 its probably just over $100 for motors/esc/props/battery.

    haven't decided yet, will probably push this way is I keep working on this thing...

    More power means I can have more weight in the design and still fly with high level control.

    Coreless vs Brushless.

    • Coreless motors are smaller and cheaper
    • brushless have more power and torque
    • Brushless esc are easy to use/connect
    • Brushless esc are cheapish..

  • DC Motor Driver

    Saul04/11/2023 at 00:50 0 comments

    I had an idea using a continuous rotation servo mod as a cheap DC motor driver with pwm input. 

    It works but not very well, maybe for an rc hotwheel but not enough power to fly and most small servos don't really like going about 5v.. so 2s 7.2v would probably not help.

    The mod also requires some expensive tiny high precision resistors, without them the noise on the signal becomes another problem..

    This should be on my other project page but whatever they are all the same to me...

    Micro + NRF PCB

    1. pwm out on 5/6 originally meant for just wireless synced RGB (Coming soon...)
    2. v2 added a tip120 for an extra Lamp output with rgb
    3. v3 became the controller board.
    4. v4 (mocked up with v2) + l293D breakout board will become the main control board RX
      • 2 dc output at 600ma each >16v input range..
      • 2 servo output
      • a couple free digitals/softservos
      • ordered the pcb so testing in a week or 2...

    if it works I've already thought about linking multiple l293D ic's in to a single I2c controled micro with 4 1.2A motor channels...

    But the scorpion need to be brushless i think...

  • Flight Control

    Saul04/07/2023 at 23:05 0 comments

    • can/should we fly without an imu? I2c pins 2/3 for micro
    • Cheap micro brushless motors aren't as easy to find anymore...
    • Using the L293D as the motor driver it needs 4 digital pins and 2 pwm for speed control.
    • The nrf board I made has 2 servo(or RGB) outputs on 5/6.
    • which leaves only p10 and 3 with pwm for speed control.
    • Might just use a softservo and then keep the open pwm for the motor.
    • For a updated board I can switch the nrf to from 8/9 to 8/4 I think and get D9 pwm free...
    • I made a breakout board for the IC, will probabaly make the updated rx pinout match for easy assembly. and a full 4/5 ch rx board for brushless!
    • The Remote pcb is in the mail but I have a working test remote.
    • micro nrf board were made for a wireless rgb project which works great. but since they match the remote pinout I don't mind setting at least one up as an rx for now.

    This project got my views in than my other one in 2 days vs 1 week. 

    So fly, then walk.

  • A quick test

    Saul04/06/2023 at 08:06 0 comments

    I think i burned out one of the motor controllers already...and the other option burned out when reprogramming...

    but anyways heres a test of it moving in parts...

    I might just use the frame design as a 2 leg 4servo walker.

    you also get to learn how hot sauce is made...

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Saul wrote 06/26/2023 at 00:43 point

umm over 100 followers but no comments? meh.... weird...

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