diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000000000000000000000000000000000000..780c968df244c094b2acdcb0ba62268ef403a792 --- /dev/null +++ b/.gitignore @@ -0,0 +1,9 @@ +.* +# Vim backups +*~ +# Eagle library backups +*.l#? +# FreeCad backups +*.fcstd1 +# Rendered STP files +*.step diff --git a/NotesAndCalculations.txt b/NotesAndCalculations.txt new file mode 100644 index 0000000000000000000000000000000000000000..29cec9c8e45dd54bf7a5c8277efe1629e8259074 --- /dev/null +++ b/NotesAndCalculations.txt @@ -0,0 +1,113 @@ +Rough force numbers: +- 50-100N maximum pitch force + - Approx 5-10kgf + - That's more than a 3l jug of milk, but it is linear.... + - Can reduce max force and just cap out earlier. +- DIMENSIONS: + - Yoke body is ~45cm wide + - Pitch arm is around half of the middle distance to the pivot (10cm) +- 10cm arm with force of 50N is 5Nm +- 20-1 reduction gear to provide 5Nm from a 0.25Nm stepper + +Desired force: +- Heavy planes require at least 0.074 daN/kt (0.74N/kt) stick force gradient + > At a speed of 300kts, this is 22.2 daN (222N, 22.6kgF) + > That's a pretty damn heavy pull, even at 300kts. What deflection is this for? + > Assume max possible deflection +- Motor torque requirements depend on the gearing and span of the yoke shaft. + +Use a stepper motor to provide feedback +- https://www.altronics.com.au/p/j0070-42-step-stepper-motor-and-lead/ +- 5mm shaft +- Minimum gear size is around 10mm wide, with 1mm deep teeth? +- Count of 10? +- Need 200 on the target gear +- using the same tooth size of `3.14mm` per tooth gives an approx diameter of 200mm +- Tge stepper as 1.8 degree steps (42 steps), using a 20-1 reduction a single + step will be 0.09 degrees (which at 10cm is a very small amount, approx + 0.1mm) + + + +Arm length is ~10cm at idle, this arm can move across a +-10cm travel +- Max extension, the arm will be at 45 degrees, and 14.1cm long +- The arm's movement range is +-45 degrees +- Main limiting factor is the travel of whatever gear is put on the arm, it + has to avoid the brace for the sensor. + - Can either use a small gear (so it fits, with no limit to travel angle), + - OR use a large partial one (with a limit to the angles involved) +- The smaller gear will probably require two layers to get sufficient torque +- A larger gear may not have the required level of travel... + - BUT, it could be hollowed out! + - Limited space still + +TODO: GET FUCKING MEASUREMENTS YOU FUCKING MORON + + +- Measurement arm: + - Axis circuluar: 27mm + - Inner raised portion: 19.5mm round, 6.5 off floor + - Spars: 2.2mm deep, 1.3mm thick + - Minimum arm length: 7cm + - Travel: +-5cm total + - [CALC] 8.6cm max arm length + - [CALC] +-35 degrees +- Space around arm axle. + - Around 24mm +- Screw pillar height: 48mm + - So, around 90mm of space vertically (from floor to ceiling) +- Screw pillar: ~55mm from middle of arm + + + +The larger of the hobby motors at altronics: https://www.altronics.com.au/p/j0026-F260-4.5V-hobby-motor/ can run at 8400rpm max efficiency +- Assuming a target speed of 60rpm (1rps) at the arm + - This can move to full extension in 100ms +- 140 times reduction to meet target speed +- Torque is 2.16m Nm at max efficiency +- This gives 0.3 Nm of torque after reduction. +- At maximum arm extension, this is: 3.5N (4.3N at rest) +- When stalled, the motor can give out 13mNm of torque, which would be 21N at + max extension + + +See https://engineerdog.com/2017/01/07/a-practical-guide-to-fdm-3d-printing-gears/ + +The above numbers seem reasonable for a first pass. +- Now need to design a 140x reduction gear arrangement. +- 7x20? 10x14? 5x4x7 (small ratios are usually a good idea) + - Recommended minimum size is 13 teeth (with 20 degree pressure angle) + - May need four pairs, this is getting crazy. +- SPACE: On the first large gear: 24mm radius (48mm diameter) + - Might be able to fit a 52 tooth gear (2.5 pitch, 20 pressure, 20mm hole) in the available space. + - Rough measurment is 44mm outer diameter, will fit. + +52 teeth = 44mm +91 teeth = 86mm (huuuge) + + +Using a stepper could work instead +- a https://www.altronics.com.au/p/j0070-42-step-stepper-motor-and-lead/ + stepper can do 0.23Nm of torque (stall) +- Multiply this by 8 using two gears (which will fit) to get 2.2kgF + +Problems with stepper: +- More complex control logic +- Slower response (motor can maybe do 600rpm at absolute max) + - 1.25 rps, 80ms travel time. + - Actually, not that much slower! + +MOUNTING: +- Steper has mounting holes, can just screw it onto something. +- Design up a bracket? Needs to be able to hold the flying gear between the arm and the motor. + - Bracket to hold the gears in place when yoke is upright + - Another bracket on the other side to hold the motor in position (needs some way of holding itself in place. + + + + + +25mm from axle to RHS edge +20mm from axle to LHS edge +55mm from axle to far +