By Insider46 on Oct 12, 2019

10  637  8

I already have a squirt but wanted to go smaller. The canopy is slightly different from the original I found it on thingiverse. It has a immortal T holder and sma connextion. And topped it off with pink color ;-).



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Kstone   Oct 18, 2019  

The duct walls are way too tall and maybe a bit to thick as well. Making the height just a little above the prop line (2-3mm) would allow for a drop in weight of 20-30%. Thurthermore, the props should be "blunt" tipped so that as much as the prop edge is as close to the wall as possible without making contact. (within 1 mm) This will increase the efficiency of the props and combined with some weight reduction, allow 4-5 minute flights.

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Kstone   Oct 23, 2019 

Some other things come to mind on re-reading all this...

  • The wall / duct thickness should always be a multiple of your printhead to ensure that the layering is as smooth / strong as possible. Thus, if your printhead is 0.4 mm then I'd suggest that 1.2 mm be the thinnest any part of your duct should ever be.
  • Wall height should be just 2-3 mm above the prop line. Please also take into account prop flex as this can be pretty significant depending on what your props are made from.
  • Nylon is your best material choice. Its strong, yet resilient to impacts, chemicals and UV. Yet light enough to be competitive with other common print materials.
  • If your flying this copter to make cool videos, then may I suggest that you remove the Ducts Aero-Lip or at least trim it down some. Reason being is that the Lip only provides its full lift during level flight. (But still adds significant weight) Soon as you angle the copter, only the leading edge facing in your direction of travel provides any lift. Worse yet, the Duct Lip has the tendency to auto level the copter to balance out the lift generated. Thus, your flight controller will fight against this change and burn through your battery faster.
  • IMO four bladed / blunt nose props work best. Should the blades stay within to 1 mm from the Duct wall, then the prop tip vortices are drastically reduced and thus the air for the next prop is smoother. This is the biggest source consistent efficiency gain so long as the props are kept close to the wall.
  • If you can, try to avoid cutting props down to make blunt ones. Making perfect cuts is next to impossible so look for the best fit you can buy and stay with that.
  • At throttle up, the Ducts walls will vibrate / oscillate unless they’re supported. This happens as the propeller blade moving past is compressing the air against the duct wall. Not only will the vibrations make it harder to tune the copter but the expansion and contraction of the duct walls will make keeping the Props within 1 mm impossible. Having a support ring around the wall, near the prop line will help reduce this problem.
Wingspinner   Oct 26, 2019 

much of what you write about ducts is not entirely true Himg been involved doing extensive reaearch on duct geometry as well as much study on the subject and having built and tested more than a few prototypes duct characteristics are very depndent on he type of duct geometry and so,e of what you say is true for the minimal type of ducts you used on you dual fan drone but are not true for these ducts shen designed these ducts based on some university and NASA research papers and the lip stall angle high close to 30 degrees even at higher speeds, so they remain effective. As well, the tall ducts are more effective in hover however the do cause drag at medium forward speed ranges and, of course add some weight. Shens prop cutter tool works quite well if you make it out of nylon or graphit - dont know why he makes the out of tpu though.very small gaps can be had by cutting the pros such that they still barely rub and within a minute of running on the ground or low hover they will fit themselves to very tight clearances only of you make the walls too thin is vinration of the ducts a problem at least 1.5mm is usually thick enough and while nylon works ok it has a relatively high expansion coefficient due to moisture and heat Stiff tpu actulally works quite well and it also dampens vibration Cf is best though for weght reasons Lastly, i agee on the weight issue with regards to this design. The shear volume of printed material on this design will make it difficult to reduce weight much


Kstone   Oct 26, 2019 

If the OP is looking for a “true” Aero-Duct, then yes, Shen's design is great. (looks super cool) Honestly though, the in-flight reality doesn't match up to the expectations for such a device. I've built enough of them to know and it’s why there aren’t more of them flying around. Which is why I've all but directly suggested that the OP use a simple Prop-Guard instead of an Aero-Duct.

The weight savings alone would be enough to offset any "performance" gains from the Aero-Duct and the Quad will feel much more responsive. At best a well-designed Prop-Guard can be used to offset the turbulence from the propeller vortices. Now as such, "if" the OP made a good set of Prop-Guards, the flight times and physical performance of the craft would be far superior to that of the Aero-Duct he’s currently using.

Side note: Here is one of my earlier designs / builds from a few years back:

While the ducts did work, they were only good during situations where the Tricopter was flying mostly level. Any significant orientation changes (angle) and only the leading edge of the Aero-Duct created significant lift. This lift fights to rebalance the ducts overall lift and in many cases was going against the inclinations of the flight controller / pilot. This would cause the FC to counteract those forces and burn through battery to mantain it's current orientation. Furthermore, the Ducts (not surprisingly) created a huge amount of drag, limiting top speed. Best way to describe it, is to compare it to a person attempting to run through Mud. Still though, it was rather fun to mess with and my son had a blast as he'd never seen something like this fly. Copter sounds really cool too as the ducts tend to muffle propeller whine so it sounds more like a helicopter than a multirotor.

joshielevy   Oct 15, 2019  

Curious what your full weight is with the camera - love the pink!

Thomaat   Oct 12, 2019  

What do you think of the flight characteristics VS the squirt? What is the difference in Flight Time?

Insider46   Oct 12, 2019 

For now I only flew it once inside and flight time was not much maybe 2/3min I can't recall. Maybe playing around with props could extend a bit?? But tbh I think the motor choice was not the best but I will have to see. Primarely it's for doing thighter gaps and fun stuff when people are around :-). When I have my 3d print battery holder I can test some more. Because I forgot some extra room for the battery strap I can only hang it with some wire lol.

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