Introduction: Sailplane Wing Installer With Electric Lifting
This is how I built my own tool for moving a sailplane wing into position so that it can be installed on the glider. I'm calling it the "Dean Rigger". Commerically made versions of these little carts sell for more than $1000 and most do not even have a powered lift for the wing! I built this one for about $70. If you have a small junk box you may have to buy a few more items but it should not cost much more than $100.
This device uses an inexpensive Harbor Freight winch that comes with a wireless remote control to lift and lower the wing to exactly the right height to wiggle it into the glider.
1 - Harbor Freight 2500 lb. ATV winch: Often on sale for $50 at their stores in the US. If you can't wait for a sale go to their website (harborfreight.com) and grab a 20% off coupon by signing up. If not in the US you can just buy it online.
1 - 2 by 4 lumber 23 inches long
1- 2 by 4 lumber 7.5 inches long
2 - wheels of about 4 to 6 inch diameter and an axle about 33 inches long to fit in the wheels, 1/2" dia. or more
4 - conduit clamps for mounting the axle
2 - aluminum tubes that nicely telescope together such as 1 1/2" and 1 5/8" diameter. I used old HG tubing.
1 - small wheel for the outrigger
1 - sheet of thin luan plywood bent to conform roughly to the bottom wing curve and fiberglassed both sides
1- 3 foot piece of 3/4" aluminum square tubing for the upper surface wing holder
2 - small strong pulley blocks, one with two pulleys, the other with one. I used Harken blocks but they are costly.
The rest consists of miscellaneous hardware, screws, junk box metal, foam padding, glue,etc.
Step 1: Step 1: Build the Frame
Cut the two lengths of 2x4 to the lengths given. Glue and screw the smaller one exactly in the center of the larger one with the larger-width sides together.
Using a hole saw in a drill press to keep it straight, cut a hole in the center through both pieces that will snuggly fit your larger diameter telescoping tube. Invert the frame and screw a piece of 1/8" aluminum over the hole to prevent the tube from slipping down under the weight of the wing. You could paint the bare wood if you like at this stage. Do not install the tube yet.
Step 2: Step 2: Build the Tube Assembly
I used aluminum tubes as they are easy to work with and I had some around. Steel could work too.The length of the tubes is going to depend on what you need for your sailplane. My tubes are sized so that the top of the lower tube is 26 inches above the floor and the maximum extension of the top tube is 43 inches above the floor. Before cutting your tubes weld or bolt a 4 inch long horizontal tube or rectangle to the top of your smaller diameter tube. Use a size that will fit inside a piece of metal C-shaped channel as you will use that channel section on the bottom of your wing platform later.
After you figure out what lengths to make your tubes to get the proper extension a bit beyond what you think you will need then you can cut the tubes. Insert the larger tube into the tube hole in the frame and mark where it meets the wood. Remove the tube, put it in a sturdy vise or clamp and draw a line from 1" above the mark to 2" below the top of the tube. Now you need to cut a clean slot in the tube just slightly wider than 1/4". I did this by using a router in a well clamped track and moving it very slowly. Other possible ways to cut the slot might be to use a dado saw, a Dremel tool, hand saw and file, etc. In any case draw a line on the tube with a marker and proceed very slowly so the slot is smooth and straight. Round the ends of the slot with a round file to remove stress in the corners. Now you can put some epoxy on the tube and insert it into the wood pieces untill it bottoms out on the aluminum plate and let it cure. Be sure to face the slot towards the side where the winch cable drum will be. (See pictures.)
Insert the top tube fully into the bottom tube untill the T at the top rests on the lower tube. Align the T section so it is parallel to the wood base. Now carefully make a mark on the inner tube (through the slot) with a soft tip marker so as not to disturb the alignment, about 1/2" above the lower end of the slot. Withdraw the top tube and using a drill press drill a 1/8" dia. hole through both holes. Now get a 1/4-20 tap and the correct size tap drill. Drill out the hole with the tap drill and then tap the hole so that it is threaded on both sides of the tube. Buy a screw eye at the hardware store that has a 1/4-20 thread and a screw shank length slightly longer than the diameter of your bottom tube. You can always cut it if you need to with a hacksaw. Bend (or cut) the eye open just enough so that you can later install your pulley block. Insert the tube in the slotted tube and do a trial fit of the screw eye to be sure the threads are working. Remove it. Clean the threads with solvent to remove any oil and apply a drop of thread locking compound (or epoxy) to the threads on the tube (both sides). Slide the tube into the bottom tube for the last time and screw the eye into the threaded hole you made by inserting it through the slot. Turn it in until it comes through the other side of the hole and binds up against the inside of the larger (bottom) tube. Back off just a bit until the tube slides up and down freely and let it harden up. Leave the eye in a vertical orientation with the opened end down.
Step 3: Step 3: Build the Wing Platform
All the commercial riggers use a very fancy composite platform shaped roughly to accomodate the bottom of a sailplane airfoil. But in reality all sailplane airfoils are not the same. So all you really need to do is curve a piece of wood to approximate the airfoil and use a generous amount of foam to protect and cushion the wing.
Get a pice of 1/8" luan plywood and cut it to be about 20" wide and nearly as long as the mid-chord dimension of your wing. Place it on your work table with 2x4's under the ends to support it and paint it with thin epoxy or (cheaper) fiberglass boat resin and apply fiberglass cloth (or to make it stiffer, carbon cloth). To stiffen the piece paint resin about an inch in from the edges on the bottom side and wrap about an inch of cloth on each side around the edges to the underside. Paint another coat of resin over the cloth and reverse side edges. Use enough to wet out the cloth.Then cover with poly plastic.Using gloves smooth out the plastic. Use small strips of wood and clamps (over the plastic) along the edge to keep the folded edges tight against the bottom side. Place a weight, sufficent to give the desired amount of curve, towards the front end of the platform so as to approximate the fit of the airfoil bottom. Allow to cure 24 hours.
Remove the edge clamps and plastic sheet. The plywood should now hold the curve somewhat. To make it stronger flip it over and apply resin and cloth as in the section above to the bottom side. Be sure to wrap and clamp a section along the edges again as this is where much of the stiffness comes from. Allow to cure 24 hours.
Remove the plastic and clamps. Cut a piece of thick metal or maybe an aluminum rectangle extrusion (see picture) and place it across the middle of the platform on the bottom. Screw and epoxy it to the platform with small screws installed from the top side. This will help stiffen and support the platform.
Now add the airfoil nose piece. Commercial riggers use nicely curved composite to approximate your airfoil but this is not really needed if you just build a sturdy C section out of wood pieces, about 7" high and screw and glue it to your base. Glue 1 to 2 inch thick foam over all the inside surfaces of this nose support and it will totally cushion the shiny nose of your sleek airfoil. Be sure to let the foam overlap the edges a bit.
Study the picture of the bottom of the platform and you can see how the aluminum C-channel extrusion is bolted into the aluminum box with tapped holes and short 1/4-20 bolts. (This extrusion will stradle the piece that you welded onto the top of your upper aluminum tube.) Drill a hole on the forward end that will be the pivot point for the platform and a matching hole in the tube welded onto the top. Use a ball-lock quick pin or a bolt with a wing nut so the platform can be quickly removed for easier transport.
The front to back balance of the wing should be just behind this piece so that the wing wants to sit level on the platform when tilted up to the horizontal. Be sure to always insert the wing holder clamp and tighten the lock screw BEFORE tipping the wing up to the horizontal position. Otherwise the wing can slide off the back of the platform.
Purchase the telescoping pieces of aluminum box metal at Home Depot or Lowes. Cut a length of the larger size as a socket for the wing holder and bolt it to the platform with two 1/4-20 bolts as shown in the picture. Also note the wooden wedges glued in place under this piece so that it conforms to the curve of the platform. (Expand the picture to see this better). I had a small knob with a screw shaft so I tapped a hole on the underside of the "socket" tube to make a lock for the inserted wing holder.
Build the wing holder as shown in the picture above by bolting a plate to the two rectangular tubes and making slotted holes in the plate for initial adjustment. I used four 1/4-20 bolts. My wing has a center chord of 39" so my longer tube is 26" and the short piece is 22". Your wing may require slightly different dimensions but this is not a critical piece as long as it holds the wing securely. The pad at the end is aluminm mounted on a C-shaped pivot bracket with a 1/4-20 bolt. Glue a pad of dense 1/2" foam over the pad, extending beyond the edges to protect the wing.
Finally cover the entire platform upper surface with a smooth, dense foam. I found a door mat at a local discount store that was made of such a foam. I used spray glue to hold it on. Paint any exposed wood on the front nose holder piece.
Step 4: Step 4: Install the Winch
I was quite impressed by what you get for $50 with this winch. It comes with a remote control system and a 4 roller fairlead for winding in the cable but because we only use about two feet of cable we don't need that so unbolt it from the winch. We also can't use the giant forged hook so using a Dremel tool and abrasive wheel, cut off the cable just above the hook. It is a good idea to immediatly apply epoxy to the end of the cable to prevent the strands from untwisting. Bolt the winch to the base as shown with the center of the cable drum at about the position of the vertical tube. I strapped the control box onto the winch motor with long Ty-Wraps. The battery is mounted on the opposite end of the base with a couple of vertical sides and a small bungee to hold it in place. I just used a 12V, 8AH, old sailplane battery. I charge it with a small solar panel while I am up flying. You should always disconnect one battery terminal before transport or storage as there is a small drain from the radio remote receiver.
You will need two small pulley blocks. I used a 2 to 1 arrangement, not to get more power as the winch is way more powerful than needed, but just to slow down the speed of lifting. The upper block has two pulleys and the lower has one. I had some Harken sailboat hardware so I used that but any medium quality pulley should work. The frame of the upper block is held tight against the tube by a radiator hose clamp. A few drops of epoxy along the bottom edge of the clamp will help prevent it from sliding downward under the pulling force. The bottom pulley is hooked onto the screw eye protruding through the slot and held vertical by small ty-wraps and a dab of silicone RTV on both sides of it. Run the cable from the winch drum up to the inner top pulley, down through the bottom pulley, back up over the outside pulley and finally down to a screw eye which is screwed into the wood base side. Secure the cable with a small U-shaped cable clamp (hardware store item).
With the frame in a vice install the battery and turn on the hand held remote control by holding down the power button. (Blue LED comes on.) Press the directional buttons and watch the operation of the vertical tube. You will have to put some weight on it to make it go down. Notice that the winch stays on a fraction of a second after you stop it. This makes it a little harder to make tiny adjustments but you can get used to this. It will go slower with the full weight of the wing on it. WARNING: Do NOT run the winch so as to hit the end of the slot at the top of the tube. It is very powerful and it will probably tear something apart if you push it beyond just touching the top of the slot. If you are concerned about forgeting this you could put a limit switch at the very top of the travel.
Step 5: Step 5 : Install the Wheels
This picture shows the (ugly) underside of the main 2x4 as I never did paint that part. You can see that the axle is held in place by 4 electrical conduit clamps screwed to the wood. One of the clamps has a copper tube inside it as a sleeve to add a little more friction. The axle is made from solid steel rod available at Home Depot, Lowes, etc. Do not use anything smaller than 1/2" diameter as it will tend to bend. The clamps are tightened just enough to allow the axle to slide so that the wing can be positioned more easily. A little grease will help.
Any type of wheels will work. Ball bearings are not nessecary. Used golf cart, scooter, baby stroller, etc. are all useable. I drilled holes in the axle and installed cotter pins and washers on both sides of each wheel to hold them in place.
An outrigger is desireable to make the cart stand up on it's own. Mount it on the same side as the winch motor. I used a steel piece about 3" wide and 18" long and screwed it to the side of the smaller 2x4 on the battery end of the base using two large wood screws. Install the small wheel first and then screw it on so that the rigger sits level on the floor. The overhanging weight of the winch motor and this outrigger will keep the cart from tipping to the other side when sitting.
Step 6: Step 6: Try It Out
It is winter as I wrote this so I don't have a video of it working. Take your machine outside, try it out and get used to it. Work the bugs out if you find any so you are ready for assembly time. Always remove the pivot bolt and the wing platform before transporting it as it will be much more stable this way.
I have found that as soon as I bring it out several people come over to look at it and this attention brings on a conversation which leads people to offer to help you put the wings on! So it has fulfilled it's duty in more ways than one! But some times when you are alone it will be your helper.