Much Googling later and I came to the conclusion there wasn't much out there. There were a few pictures of simple single-hinge wings but those weren't very impressive to me, and the professional version was well over a thousand dollars and not what I was trying for anyway.
Since there weren't many how-tos out there, and since nobody had really done what I wanted to do in an affordable (mostly) way, I tried to take some pictures and help others who want to build wings that open and close without manually pulling strings.
Steampunk Hawkman is the result. This is a tutorial on building his wings (V1.0).
Step 1: Planning
They're fairly similar, although skeletally they're a bit different, so I chose bird, just because there's more of them out there.
This diagram shows a greatly simplified way of creating the parallelogram that does the work. When the base of the wing is attached at the ends, moving any of the members should cause the wing to fold and unfold.
Originally, due to all the manual wings I saw, I thought only about pulling or pushing on the attached ends, but once built, it became clear that any change to one of the angles affects all the rest. That opens up a lot of ways to cause the folding motion.
Step 2: Prototype
If I could make something neat out of 12 dollars worth of trim, I knew I'd be onto something.
I used a 1-foot to 1-square conversion and cut the lengths, then I drilled the holes and threaded a bunch of nuts and bolts I'd picked up at Home Depot as well.
Holding it to my back with the wings outstretched it becomes clear that the first measurements I guesstimated would do just fine.
Since then I've played with different lengths and the 2:3:4 range seems to provide the best bang for the buck to begin with. It provided about 8 feet in width and height, fitting into most rooms.
Step 3: Materials
So I wanted these wings to be reasonably portable, as light as possible, and to be able to get them off and on quickly (Halloween is COLD up here and you don't want to be outside after a party trying to get the pieces off). I needed to make the wings into a backpack.
I decided on re-using a backpack I had lying around. Due to the size I wanted, I chose a backpack with a waist strap. A good strong strap to secure the arm straps together will also help with being able to raise your arms. If the straps are pulling back against your shoulders, your range of motion will be greatly limited, although not enough to cause problems.
To this backpack, you wilI need to add a baseplate for bolting on the wings and hardware. A piece of 2 foot by 1 foot plywood seemed to do the trick for me. You can then trim it down to get rid of excess wood later.
You will need nuts and bolts. I used 1/4" bolts for mounting the wings themselves and the pistons, since they take a lot of stress. For hinging, you can use a smaller bolt. For the pistons, you need 4" bolts.
4 1/4" wide by 4" long bolts with nuts for the pistons.
7 1/4" wide by 2.5" long bolts for attaching the wings and backpack
10 smaller bolts, still 2.5" long for wing pivots
14 metal washers, at least 1.5".
50 pack of smaller washers (although the bigger ones will work fine, you just need these for the wing pivots. Your mileage may vary, but if you don't have a drill press, I recommend using washers wherever possible)
The wings will be made of square aluminum tube. This will make it easier to drill holes through nicely. Using 1-foot per square in the diagram, I bought about 60 dollars worth of tubing.
In my area we have a store called Princess Auto. It's basically a huge cheap hardware/surplus store. I understand a place called Harbor Freight also serves this purpose. From here I picked up the pneumatic tubing, push-on connected, the pistons, and a pneumatic switch. I bought a 5-way 3-position switch. 3-position is the important part. It allows air to move in both directions AND has a neutral position. This allows you to switch off the air. That can be handy when you first start playing with air power. I have since changed to a 2-position switch, but one must be careful when pressurizing a system like that, since it could open or close if it's been messed with between pressurizations. In practice this didn't happen once we were used to playing with air, but it's good to keep in mind.
Speed limiters are NOT NEGOTIABLE. This is your obligatory safety warning. The wings don't weigh much, but they could whack someone, and you don't want to Be That Guy. Start with slow, work your way faster slowly.
These pistons are available in many sizes, but I chose a 4-inch throw. They were under 20 dollars each. 100 feet of tube was about 10 dollars, and the fittings for connecting everything (splitters, speed limiters, etc) were about 2-4 dollars each.
Power was the last piece of the puzzle. I originally planned to buy a linear actuator (a sort of electrical piston, if you like), but they were very expensive. However, the air-powered ones were quite affordable, so I quickly hit on those, but wasn't sure how I was going to power them. Googling for portable air tools brought me to Liquid CO2.
Liquid CO2 is very high pressure, but the kit-level hose and fittings weren't going to handle those pressures. I needed a regulator.
Enter the Jacpac. It turns out that this is a CO2-based air tool pressurizing system that allows you to use air tools without being attached to a compressor. It's a professionally built (and I've been using it for tools as well) regulator that puts out exactly the pressure you need to do reasonable work with air. This piece of equipment goes on sale for 70 dollars, but is normally about 100. All this stuff is available in pieces but since I wasn't an expert, I went with the pre-built solution for this, and I've had it for 2 years now and it's a great piece of kit.
CO2 tanks and refills are quite affordable and easy to find at paintball supply stores. I bought a spare but the rig comes with a 9oz tank. That's good enough in a perfect world for 2 full nights out at least. I picked up a 20oz tank which has become my main tank since then, but during testing, I got 88 opens and closes out of the 9oz tank so it should be quite useful.
Step 4: Make the Wings
So with my 1-square to 1 foot ratio, I cut the pieces with a hacksaw. Aluminum is pretty easy to cut this way. To make the hinge holes 'correctly' you want to use a drill press so everything is a perfect 90-degree angle and all the holes fit nicely.
But what I HAD was a drill. So I carefully employed the old Mark I eyeball, and did the best I could. Just mark off with a sharpie and make your holes as perfectly vertical as you can. It can be a good idea to pick up a metal file to take any sharp bits down. Nobody touched the wings, but you never know.
To prevent a lot of the trouble associated with imperfectly vertical drilling, I put a washer in between each member when I bolted them together.
(Important note: I used steel nuts and bolts. Steel and aluminum will corrode if kept in contact with each other due to their 'galvanic number'. In practice, this probably won't affect a normal hallowe'en-only usage for several years, if at all)
Once the holes were drilled, I had two 'wings' that would fold and unfold.
Step 5: Make the Backplate
There are basically 3 attachment points to worry about so it's stable.
Left and right, so the wings don't just rotate around you when you move, and one at the bottom to keep them in the same plane as you are. This way they won't open and then flop forward over you. Higher wings look cooler, lower wings are more stable. Note in the first picture, they ended up being just below my shoulder blades. I would have liked them a bit higher and did that in my next version.
I use an awl to make holes in fabric rather than drilling through it. Be sure to use the widest washers you can, on both sides. You REALLY want to get these tight, and the more surface area you have when you're pinching a washer down onto the backpack material, the more secure it will be. No washer means it'll rip as it rubs against the threads on the bolts.
If you look carefully you can see where I originally had 2 holes at the bottom. This was overkill, and cutting away as much of the heavy wood as possible was much more important in the long run. This is the general shape you're looking for though. Later you can cut away more if you like.
Put it on. Wear it a bit. Get used to it, you'll have it on for a while and you need it to be comfy.
Now take it apart but place the hardware aside in a place you can find it, you'll be putting it back on soon.
Step 6: Mount the Wings.
You must now mount them to the wood. Basically the way I did this is trial and error. You want the nicest looking (for your purposes) look while open AND while closed, so play around a bit before you drill. You'll be able to try a few times with a nice thick piece of plywood backing, but better to play now.
Notice, this being my first go, the measurements aren't perfect. There's quite a bit of forgiveness here as most people will just say WHOA, and you will be moving. If the wingtips end up being close to the same height, it'll look fine. Do measure everything twice though. You can see here a lot of the test holes and mistakes I made while figuring it out THIS far.
Step 7: Hooking Up Air.
With the wings mounted on the back you can re-attach the backpack and get everything working and moving nicely just using your hands. Use washers wherever you can to reduce any tightness caused by nuts and bolts pressing directly against the tubing. I use large ones so that there was less change of warping the tube walls if I overtightened. Do not overtighten.
Okay you now have a pair of folding wings attached to a backpack. It's time to think about making them open and close.
First you need to see what a 4-way 3-position switch works like:
This switch has 3 positions:
Position 1: Air goes in at the bottom, and it goes out the left, pushing into the top of the piston and opening it downward. The right hand side is vented to exhaust.
Position 2: Air goes in and goes out the right, pushing into the base of the piston and closing it. The right hand side is vented to exhaust.
Position 3: No air goes in, Exhaust is closed. This means you can turn the whole rig 'off' in the open OR closed position.
I recommend playing with this setup before trying to attach it. You need to get a feel for how fast the pistons can open. Keep in mind that this 4 inches will translate to several feet as well. Essentially, unchecked the wings can open in the blink of an eye. Place speed limiting push-on attachment on all four ports of the pistons. Practice with them until you have a nice even speed, say about 1" per second. You may speed this up later but starting slower is ALWAYS better.
If you can access a compressor, the Jacpac uses standard fittings, so you can run perfectly normal compressor air into the system to avoid wasting CO2.
Step 8: Attach Power to the Wings
Now we need to figure out WHERE to put the pistons on the wings.
To do this, you need to measure the exact throw of the piston (how far it opens) and the length of it.
You can also do some math to figure out the chord length of a circle, or you can do what I did and use the old Version 1.0 Eyeball.
We'll use my 4" pistons as the example here, since they have been installed and used at least twice and worked well.
I originally wanted to use pulleys, and/or mount the piston on the backing board. This means that you need to have a ton of nuts and washers to get everything in the same plane, and even then, any variation cause the wings to tear themselves away from the wood. It's just too picky using this method. We will deal with board-mounted pistons in V2.0.
It's MUCH easier to mount the pistons on the wings themselves. This way they fold and unfold without pulling or pushing against anything other than themselves. This was a much more stable solution and the wings worked well for over a year until I took them apart for V2.0.
Measure the piston from center of mounting hole to center of mounting hole. Mark this on a piece of wood (I used a piece of trim from the prototype). Also mark the same holes with the piston open on the same piece of wood so you have a measuring stick with both distances on it.
The piston throws 4 inches, so we know the best place to mount them is somewhere NEAR 2 inches from the highest pivot point.
Fold the wings closed completely, and mark with a pencil the spot about 2 inches from the top pivot point. This is in the middle of the 'wrist' part of the wing. See where this puts the bottom of the piston. Mark this spot as well.
Now open the wings, until the first mark moves completely from the closed distance to the open distance you have marked on the stick. This is where things get subjective, because the requirements for the open position depend on personal taste. Some people like the wings completely snapped. I liked them for this costume just over horizontal.
If the wings don't open quite enough, for you, erase the marks, fold the wings and start again, moving the top of the piston slightly closer to the first wrist pivot, until you have the effect you desire.
For durability, and to prevent the wings from warping, you want the pistons to be pushing in the same plane with everything else. Since the tubing is highly unlikely to be the exact width of the pistons, you will need to use the long 4" bolts and a series of nuts and washers to make the piston as close to straight as possible. Tighten down the mounting bolts with washers and nuts first, then start adding nuts and washers until the piston is as flat as possible in relation to the wings. The piston is going to push against this bolt, which is why I recommend the 1/4", it's going to take the most stress in the whole system.
Step 9: The Complete Rig.
You now have a much better start than I did. I'd be happy to help clear up any remaining issues and update the instructions if anything is missing, please let me know.
Version 2.0 wings still to come, they require more shop skills, but are correspondingly more epic.
Here's a sneak vid of what this style of wing looks like opening and closing: