How would you design a cyclocopter?

[NickRehm]

I posted this article about cyclocopters hoping to inspire the community to consider building their own. I'm curious what design changes would you make if you were to build your own of this type of rotor/vehicle? Either to improve the concept as a whole, or simply improve manufacturability

 

[Crawford Bros. Aeroplanes]

I remember this concept being used to propel the planned airship Skylifter. They found it was a simpler mechanism for vectored thrust in any direction, much better than rotating fans.

 

[bracesport]

@Rcjetflyer2 - very nice - novel and inventive!

I do have a slightly unrelated question, you seem to have mastered the film onto the 3D printed wings - what technique did you use?

 

[NickRehm]

@Rcjetflyer2 - very nice - novel and inventive!

I do have a slightly unrelated question, you seem to have mastered the film onto the 3D printed wings - what technique did you use?

The blades are built up using 1/16" carbon fiber ribs, and a few spars along the length. They're covered using the lightest monokote we could find--simply applied with an iron to the ribs, and a little CA glue in the tricky areas

 

[2jujube7]

I posted this article about cyclocopters hoping to inspire the community to consider building their own. I'm curious what design changes would you make if you were to build your own of this type of rotor/vehicle? Either to improve the concept as a whole, or simply improve manufacturability

I'm planning on scratch designing and constructing a cyclocopter later this year as part of a school project in engineering class. I only know the basics of how one works, and I'm hoping that will be enough for me to test, experiment, and design one

 

[PsyBorg]

 

[Scotto]

I posted this article about cyclocopters hoping to inspire the community to consider building their own. I'm curious what design changes would you make if you were to build your own of this type of rotor/vehicle? Either to improve the concept as a whole, or simply improve manufacturability

View attachment 169827

Congrats on building and flying that. It looks awesome. Here are my 2 cents on design changes.
1. Foamboard wings 20 to 30 inches wide.
2. 2 wings per rotor like most props and helicopters so they operate in cleaner air.
3. Make it in a "quad" type arrangement.
4. Big single motor or 2 going the same speed geared way down.
5. Have all the control come from servos and linkages so ideally you could fly it with a basic 4 channel and maybe a more standard gyro stabilizer?
6. Maybe stagger the front and back so in forward flight the rear would be in cleaner air?

I was just dreamin but now I kinda want to try it. How do you figure the ideal ratio for distance between wings in the rotor?

 

[2jujube7]

I was just dreamin but now I kinda want to try it. How do you figure the ideal ratio for distance between wings in the rotor?

I forget which research paper I read it in, but I saw somewhere that for efficiency's sake, it's best to have the chord of the rotor be 1/2 the radius of the rotation of the rotor.

 

[2jujube7]

I guess this is where I'll post updates on my project. I finished printing out some new parts and assembled them. Here's some pics:

Currently the driven gear is clearance fitting onto the center shaft, so I think I'm going to try and make/file a "D" shape connection between them instead of the regular "O" hole. Other than that I think it'll work pretty good. Let me know if anyone is interested in files/more pics.

-- Jude

 

[Scotto]

Awesome! Ya I want to see more of that! Is the white part all 3d printed? It looks like foam.
I had another thought and I might be all wrong but if you have a symmetrical airfoil, you would have about the same pitch, drag, and lift at 12 o clock as 6 o clock, right?

 

[2jujube7]

Awesome! Ya I want to see more of that! Is the white part all 3d printed? It looks like foam.
I had another thought and I might be all wrong but if you have a symmetrical airfoil, you would have about the same pitch, drag, and lift at 12 o clock as 6 o clock, right?

Yep, everything is 3D printed! Well, except for the bearings, motor, center shaft, etc. No foam at all. Based on my knowledge, you are correct about the airfoil. However, I'm lazy and a flat-bottomed airfoil like the Clark Y prints easier. I don't really want to spend time sanding down the bottom of the airfoils and removing supports, at least when I'm generating not very much thrust. On later versions, I will have to make a symmetrical airfoil in some way, good catch.

 

[Piotrsko]

You dont want lift at 6 o'clock which will happen automatically with a flatbottom. Might need a trimtab to keep it at a positive angle of attack or a up radiused nose like a NACA laminar series to provide apparent angle of attack.

 

[NickRehm]

I guess this is where I'll post updates on my project. I finished printing out some new parts and assembled them. Here's some pics:

View attachment 192548 View attachment 192549
Currently the driven gear is clearance fitting onto the center shaft, so I think I'm going to try and make/file a "D" shape connection between them instead of the regular "O" hole. Other than that I think it'll work pretty good. Let me know if anyone is interested in files/more pics.

-- Jude

Yes keep them coming!

 

[2jujube7]

You dont want lift at 6 o'clock which will happen automatically with a flatbottom. Might need a trimtab to keep it at a positive angle of attack or a up radiused nose like a NACA laminar series to provide apparent angle of attack.

Why wouldn't lift at 6 o'clock be good? In the research I've done, I haven't found anything on it being undesirable. Sure, on an unsymmetrical wing it would have a lower lift to drag ratio at 6 o'clock than at 12 o'clock, but I wouldn't think that it would be too bad for a little RC model.

 

[Piotrsko]

Lift =drag. No lift reduces drag to minimum thereby reducing power required in a place where lift is not required. It may have a minimum impact, but why not optimize for free? My $0.02 and I'm sticking with it.

There's one of these over on hackaday in an article about dRehm computer control

 

[NickRehm]

Lift =drag. No lift reduces drag to minimum thereby reducing power required in a place where lift is not required. It may have a minimum impact, but why not optimize for free? My $0.02 and I'm sticking with it.

There's one of these over on hackaday in an article about dRehm computer control

That's incorrect

 

[2jujube7]

Lift =drag. No lift reduces drag to minimum thereby reducing power required in a place where lift is not required. It may have a minimum impact, but why not optimize for free? My $0.02 and I'm sticking with it.

There's one of these over on hackaday in an article about dRehm computer control

Hmmm yeah Piotrsko I guess I see what you're saying. However, lift generated at 6 o'clock would also contribute to the overall lift and help it to fly. If it did not contribute, you'd need to either run the motor at higher rpms to generate all of the needed lift at 12 o'clock or you'd have to (almost) double the "wingspan" of the rotors. With a nonsymmetrical airfoil, it wouldn't be as efficient at 6 o'clock, but a symmetrical one would do the trick.

 

[Piotrsko]

IIRC, you were running a foward highpoint flatbottom, (not sure it's a clark variant looks gottigen but still high drag) if you change the airfoil to semi symmetrical then my 6 oclock comment becomes non relevant.

 

[2jujube7]

Time for another update! I put the servos in it and tested it out. Sadly, it didn't work very well. The big ring (on the outside that gets moved around by the servos) rotates slightly when I try and move it in one direction or another. After a few times moving it, the ring rotates too much and gets caught on the "sliders" that hold it onto the green cross pieces. Then, the servos makes strained noises, it can't move, and (I thought this was cool) it heats up the green color change filament to a yellow color around it. I'm thinking that maybe adding a bigger bevel/chamfer onto the friction points of the sliders/ring would help, but I'm not sure. Hmmm... I have to figure out some other way to vector the ring around. I'm also having trouble adapting the 5mm motor shaft to the 1/8in gear ID. I tried printing out an adapter (you can see it in the picture), but it turns out that an 1/8 wide cone of 3D printed ABS isn't very strong, who would have thought!

Oh, and here's a link for the Onshape project: link Not sure if anyone here uses Onshape or is interested in the files, but you're free to look around if you are!

 

[2jujube7]

I did some research and completely redesigned the vectoring mechanism. In order to keep the ring from rotating, I had to incorporate a different kind of sliding system. (I got the idea from the Y carriage of the Foam Ripper/other homemade CNC machines) Linear bearings are relatively expensive, and unreliable when you get them cheap. I decided to use regular bearings, as it would be cheaper. Here it is so far (In CAD, in case you can't tell):