400mm EDF project

[Boberticus]

how close were you to full throttle before the failure?

you balancing the blades at all?

have you considered covering with fiberglass?

that looks ****** dangerous to me and a good reason to keep tweaking things to get it to completeion.

Largest FDM printed propeller in the world right now? not largest working though... at least not yet.

 

[SkyersJet]

The latest prototype

 

[Marzipan]

@SkyersJet I get an error message when I try to view your new prototype video.

 

[SkyersJet]

oh dear, try this link

 

[SSgt Duramax]

That is epic. In a weird way, it kind of reminds me of this sound. C5s back when they were good and loud before they converted them all to M models. It is still odd to see a C5 flying through the sky not bursting ear drums with that rumbly shreik they had. Speaking of cool things to do with oversized EDFs..... What if you made 4 of them.

 

[SkyersJet]

I agree, loud jets are so much cooler. I hope to make more at some point, maybe 4, yes.

 

[SkyersJet]

I tested it at 12s, it didn't go well

As a result I added steel rings to reinforce the duct and stop it from flexing:

Then I did some tests of different blade pitches on 6s

Here is a PDF with more data and theory
http://www.skyersjet.org/resources/(web-version)-The-Effect-of-Geometric-Pitch-on-Fan-Efficiency.pdf

 

[SSgt Duramax]

Phew. I was waiting for a boom. Glad there wasnt one.

Not sure how i feel about trying this myself having just had a spinner explode. It was pla though.

Have you thought of using ABS?

 

[quorneng]

Skyersjet
Nice!
Having got it to run reliably I suppose the question is how much thrust does it produce and how much does it weigh?

How close is it to being a flight capable package with a thrust/weight ratio similar to a big EDFs?

 

[SkyersJet]

Skyersjet
Nice!
Having got it to run reliably I suppose the question is how much thrust does it produce and how much does it weigh?

How close is it to being a flight capable package with a thrust/weight ratio similar to a big EDFs?

These are the latest predictions

https://twitter.com/i/web/status/1497649934191022093

 

[SkyersJet]

Phew. I was waiting for a boom. Glad there wasnt one.

Not sure how i feel about trying this myself having just had a spinner explode. It was pla though.

Have you thought of using ABS?

ABS is difficult to print and toxic. I used to use PETG but I was recently convinced to try a special PLA, it is really good. If it grenades there's always nylon.

 

[SSgt Duramax]

ABS is difficult to print and toxic. I used to use PETG but I was recently convinced to try a special PLA, it is really good. If it grenades there's always nylon.

Yeah, is it the tought PLA? I have heard that stuff is pretty fierce. You need good ventilation to print ABS. If I ever print ABS, I will have an enclosure and an exhaust set up to outside the house. I hope it works out for you, what size ESC do you think you will need?

I hope you are able to use this in something. Maybe a giant L-39 or Cirrus jet.

 

[SkyersJet]

The PLA I use is as tough as ABS but much easier to print. It's called PolyMax PLA, try it. I have a 14s 200A Hobbywing ESC.

That would be cool, if anyone wants to collaborate on that I'm willing. My own dream is a VTOL, the Yak style rather than the Harrier with two EDFs, one front and one back as lift jets and either one EDF or a pusher prop for forward flight.

 

[SkyersJet]

 

[Bo123]

Now put it on a plane.

 

[SkyersJet]

The SkyersJet EDF is back! (in a smaller version and unfinished). People have been asking for the files for about 2 years but I wanted to finish testing it. Due to cost I don't know when that will happen so I am just releasing files and instruction as I go along. If people are still interested I'll continue with it.

Files: https://www.thingiverse.com/thing:6211589

This is still not the 400mm however, that has severe vibration problems due to bad tolerances and needs to be entirely rebuilt. This is a smaller version that's a) easier to print and b) I made a gearbox with proper backlash and tolerances this time (H8-f7). Some people hate the gearbox however so I may produce a direct drive version at some point. You can also do it yourself; not only are STL files included but carefully annotated 2D drawings of every dimension for reverse engineering.

Two very important points: 1) If you somehow succeed at building it without a BOM and build video please take proper safety precautions i.e wear goggles and test it outside or in a safe room. 2) Do not print anything that hasn't been already supplied as a STL. That includes the rotor hub that the blades attach to. I wouldn't attempt this build unless you are prepared to buy some stock parts and have others machined. If you choose to rig it for direct drive then all you have to machine is the rotor hub and buy some screws. Should cost maybe £100. Use aluminium. If you stick with the geared version you don't have to machine the gears I provided links to suppliers of them but any will do so long as they are of the same dimensions and module.