Mini-Ornithopter Prototypes

Somewhere around 1996 I got caught up in that Magic: the Gathering card game that was going around like the flu. One of the cards, the Ornithopter, had a picture of a set of wings made from sticks and cloth that I found facisnating. I haven't played the game in years, but that card got stuck in the back of my memory, probably because its name is fun to say.

I've had a resurgence of interest in these devices thanks to the growing popularity of micro air vehicles (MAV), like palm sized helicopters and quadcopters, and suddenly had the need to try build my own ornithopter. This Instructable documents my recent  attempts at crafting my own micro-orithopter from inexpensive components. This is really more of an Instructadon't, as none of these prototypes actually fly. I'm close to having a working version in the air, when that happens l will also create new Instructado using a more conventional format.

Project Goals

1. Design and fabricate a palm sized flying machine using 3D printed parts
2. Non-3D printed pieces, such as structural material and electrical components, must be cheap and easily to find.
3. Printed parts should total no more than $10 when being made from ABS plastic or similar.
4. Total cost should not exceed $40, including RC.
5. Design and fabricate a Infra-red receiver and transceiver for remote control
6. Small is the name of the game! I'm shooting for a wingspan of less than six inches.

Materials Used

1. Spring Steel, aka Music Wire. hobbylinc.com
2. Guitar Wire
3. Miniature Motor, common pager style solarbotics.com
4. 40mAh Lipo Battery sparkfun.com
5. Tissue Paper
6. Plastic Film, various thicknesses
7. Sewing Pins
8. Gorilla Glue

Design Software and Tools

Objet Printer
Up3D Printer
123D beta9, Autodesk Inventor Fusion
Dremel, scissors, wire cutters, micro drills

Step 1: Initial Design and Material Testing

While building the first design I had three main objectives: to make a working mechanism, to test different materials for strength and flexibility and, most importantly, to make it look cool. I know next to nothing about the science of flight, so I wasn't all that surprised when the first prototype nose dived. The important thing was that I learned why it was failing and how I might correct it.

In the pictures you can see parts of the ornithopter printed from different materials.  These were all printed on Objet 500 UV cure 3D printers that are able to mix a rigid material with a flexible material while printing. To test these materials  I made several separate prints using different ratios of rigid and flexible at different thickness. The parts were then assembled to a semi-functional state and stress-tested to determine what combination made for the best ornithopter.

The type of material that comes out of these photopolymerization printers is very similar to plastic, but it's not quite the same. Thin pieces tended to be floppy, and thicker parts were prone to snapping. These materials were not intended to be made into mechanical parts. As far as durability was concerned, I was having much better luck with pieces made from ABS plastic printed by an Up3D. ABS is plastic, and I think that will be strong, flexible, and light enough to be used in the final version.

I learned a lot from this first test model. For one, the small gear ratio didn't provide enough  torqueto flap the heavy wings. More importantly, I started to realize that slapping on ad hoc paper wings and expecting the craft to actually fly was a bit optimistic. I did find a suitable material, the gears and linkages were working, but the wings were flat and lifeless. I went back to my virtual drawing board and started on the revisions.

Comments

[Manick Yoj]

Fascinating and very fun. I love watching and reading the videos and research you've put in here and I wish you the best of luck with your future flights!

[spylock]

Too cool,youre a brainy mug no doubt.

[zack247]

if im not mistaken this works in a very similar way to those "dragonfly" toys that used to be sold, but this is incredibly cool nonetheless!

[Tomdf]

Oh yeah, you are dead on, I think those toys might have even evolved from versions made by hobbyists. They essentially the exact same thing. I certainly could just go buy one, but it wouldn't be near as much fun for me.

Thanks for the comment, Zack.

[zack247]

of course it wouldnt be as much fun, wheres the fun in simply buying something? :P

[stihl88]

http://www.rcgroups.com/forums/showthread.php?t=1073892

[Tomdf]

Thank you Stihl, that stuff is amazing and preddy much exactly what I'm trying to emulate. I can't believe those guys just up and make their own brushless motors, crazy!

[germeten]

There are some excellent 'thopter videos on Youtube. One particular Japanese inventor builds life-size RC bats, birds, insects, flying reptiles which apart from the squeaking mechanicals are hard to tell from the real thing. He also has several videos of construction techniques and details. See: http://www.youtube.com/user/BZH07614?feature=watch

[Tomdf]

Whoa, that guy is super human. This link is going to be a big help. Thanks :D

[M.C. Langer]

Beatiful work!!!! :-)

[Tomdf]

Much appreciated :D

[MikeTheMaker]

I love the "Inaugural Flight" video--the device is skillfully made and well thought out . . . also it's inspiring; makes me want to give it a try.

[Tomdf]

Thanks mrigsby

[SNEHALCHEVLI]

GOOD

[stringstretcher]

Nice stuff!

[stihl88]

http://www.rcgroups.com/forums/showthread.php?t=596219&page=55

[msurguy]

Very fascinating info and test development here, Tom! Love the idea to 3D print the parts but afraid they will be too heavy, some of the things could definitely be replaced with Carbon Fiber alternatives for a lot more durability and feather-like weight. I have carbon fiber rods 0.2mm, 0.3mm and 0.5mm diameter that would be perfect for this king of development, I'm sure a hobby store near you carries some thin carbon fiber rods as well (maybe not as thin as mine because these are specialized for MAVs). There are also carbon fiber tubes out there that can house the rods by inserting the rods inside which gives you some freedom of how to make the skeleton of the ornithopter.

Do you want me to find some links for Japanese ornithopter makers? They have lots of tips on their websites and I am sure even the schematics and code for the RX and TX for the lightest models. Just let me know and I'll look!

[Tomdf]

Thanks Surguy. I think you are right about the 3D printed parts, the smallest gears it can make are too big for a tiny ornithopter. I am having a lot of fun finding ways to cut weight down though, I definitely want to try some of those carbon fiber rods. I also need to get some sockets so I can make those mini-connectors that you wrote about.

I've got the TX and RX figured out, I think, using picaxe, but if you do run across some cool sites I would sure like to see them.

[msurguy]

http://blog.goo.ne.jp/flappingwing/
http://www.oyajin.jp/~toko/contri/2005/index.html
http://blogs.yahoo.co.jp/watasidesuyo49/MYBLOG/yblog.html?m=lc&p=3
trhk.exblog.jp
http://translate.googleusercontent.com/translate_c?depth=1&hl=ja&ie=UTF8&rurl=translate.google.com&sl=ja&tl=en&twu=1&u=http://trhk.exblog.jp/i16&usg=ALkJrhgThzIu18NxaF5fM6wvRuS3hIMPbw
http://blog.goo.ne.jp/kobara3211/2

TX info http://www.kyoto.zaq.ne.jp/tkd/transceivmemo.htm
RX info http://www.kyoto.zaq.ne.jp/tkd/airplaneready.htm

[Tomdf]

Wow, thank you. I got a chance to weigh some of the parts I've been using and they are really heavy! My motor alone weighs 2.5g, that's twice as heavy as some of the ones I've linked.

[Easily a-Mused]

I think I have to make this. Even if it doesn't fly. I know someone with this obsession with thopters and I think he needs one of these. Or three. (I am not an enabler... *shifty eyes*)

[Tomdf]

Be sure to check out the videos and links on the last step for examples of ones that do work.

[ynze]

Wonderful instructable! I find the mistakes and the instructadon'ts at least as useful as a flawless how-to I'ble. Thanks!

[Tomdf]

Thanks, I figured that at the least they are fun to look at :)

[rimar2000]

Amazing work!

I speak without knowledge about the matter, but it seems you have too much demultiplication of the motor.

[Tomdf]

Thanks, chances are you are correct. I might give up on using 3D printed gears and get some real ones that supply a better ratio.