So as it turns out, i designed my previous propeller wrong and i had to completely redesign it
Used NACA 4424 as the root
NACA 4415 for lower midsection
Eppler E205 for mid midsection
NACA 1408 for upper midsection
NACA 0006 for tip
Propeller blades
Today I decided to get a start on my actual propeller blades. This took way longer than expected.
I used many different aerofoils throughout the propeller’s length as the speed experienced at each length is different.
NACA 4424 for the propeller root as its thickness provides structural strength
Goe 387 for the lower midsection as it has a decently high stall angle
NACA 4412 for the upper midsection as it has low drag and high lift coefficent
NACA 2412 for the blade tips as its thin profile provides low drag at high speed
The loft command in solidworks was solid-not-working, making this a major headache.
Next i plan to work on the lock for the back of the gearbox and hopefully on the secondary propellers, I hope the bevel gears don’t take me 6 hours to figure out how to make to ISO specs :/
Ring Gear and Handle
I spent some time making the carrier pins for each layer of planets and the ring gear. My gears are set up in a 64/16/32 ratio (Ring, Planet, Sun). I’m going to layer 3 of these stages together to achieve a total reduction ratio of 8:1
The carrier pins are set up on my sun gear. I have designed small raised sections to prevent excessive plastic-on-plastic rubbing, these raised sections also give lubericant a place to sit, reducing overall friction which is critcal for a backdriven gearbox like this.
From experience, a little bit of friction at the very end stages will result in a very large effect, often making the system completely undrivable. This is because the 8:1 total reduction ratio means for example 3N of friction in the last stage will translate to 24N of additional force needed to start spinning
The ring gear is split to allow the herringbone gears to actually be assembled. (I’m not letting my lack of DFA getting the better of me again!)
Next I will work on a handle and gearbox lock mechanism, if i have time i may start on overall housing design and/or propellers
#Initial concepts and beginning to make the gears.
Based on my previous pre-stardance model, I will be using herringbone gears so that the teeth engage gradually, reducing noise. Herringbone teeth also cancel out the axial thrust of standard helical teeth.
It is 22:55 local time for me so im ending my session early today. Designing the carrier and ring gear will happen next.
