The next series of photos and text represent the process for sheeting a set of foam wings for an EF-1 racer. In this example I use Gorilla Glue. However, if you wish to use epoxy it is exactly the same process.
To start I assemble the end of the joiner tube supports. Each panel receives a 3/16" balsa component capped with a 1/16" balsa sheet.
The cores are marked where to cut the foam to receive the balsa assembly. I use a X-Acto blade to cut through the foam.
Install the end block assy and paper joiner guide tube as shown below. Repeat for the second panel.
EF-1 Foam wing sheeting (DK Rickey Rat/Miss DARA)
EF-1 Foam wing sheeting (DK Rickey Rat/Miss DARA)
- Attachments
-
-
- Make sure you assemble a left and right set of components. The 1/16" balsa is installed towards the tip, and the space above the spar tube hole is narrower on the top side. I just assembled a wing using the supplied parts and they may need an additional 1/8" balsa added to the top to match the top surface. If needed add 1/8" balsa to the top side after assembling the 1/16" sheet.
- EF1 BALSA END SUPPORT.JPG (24.46 KiB) Viewed 3091 times
-
- I learned the hard way, the end of the tube needs to be capped with balsa or tape to prevent glue from entering the inside of the paper tube while it is glued in place.
-
- The distance from the LE to the front edge of the block should be 50mm as shown and must be consistant panel to panel to keep the wings square.
-
- Cut the foam away to allow the end block to be installed into the foam.
-
- Slide all the components into the foam core to make sure everything fits prior to gluing. At this point you may realize the end block assy is shy of the top surface. Add balsa as necessary.
-
- For this wing, I used Gorilla glue as I plan on using the same glue to attach the sheeting.
-
- Gorilla glue is added to the paper tube.
-
- Install both the end block and tube and set aside to dry.
-
- I apply masking tape around the end block to prevent gouging or sanding the foam core.
-
- I use a flush cut saw to remove the excess balsa prior to sanding. This is the bottom side being cut.
-
- Sand the block flush with the surface of the foam core.
-
- At the root some excess glue foams through the top surface, this must be sanded prior to advancing with the assembly of the cores. Repeat the cutting process for the end block on the top side of the cores.
-
- Add spackling compound to the voids in preparation for sheeting. Sand when dry.
Last edited by kane on Tue Feb 06, 2024 12:14 pm, edited 1 time in total.
Re: EF-1 Foam wing sheeting (DK Rickey Rat/Miss DARA)
Sheeting a foam wing cont:
(DELETE DUPLICATE POST)
(DELETE DUPLICATE POST)
Last edited by kane on Mon Feb 05, 2024 3:40 pm, edited 1 time in total.
Re: EF-1 Foam wing sheeting (DK Rickey Rat/Miss DARA)
Sheeting a foam wing cont:
The next series of photos will show how I prepare sheeting and sheet the wing.
You will need 8 pcs of 1/16" X 4" x 36" balsa to sheet a full wing. Yes you will have some scrap. I use a full width sheet along the LE, a second sheet along the TE trimmed to mate with the LE and then a wedge shape in the middle. The key to having good sheeting is making the mating surfaces square and flat. There are several ways to accomplish this. I use a sanding block and the edge of my bench. The end of my bench keeps the block square and the sheet is sanded relative to my bench. Thankfully, my bench is pretty square. I use the top of one panel to create my sheeting as this is the longest side due to the airfoil shape. It is critical that the finished wing matches the final dimensions on the plans to meet the min wing area rules. You should be shooting for 10.75" at the root and 7" at the tip. This is from the front of the foam core (NOT including the 3/16" LE to the end of the sheeting. NOTE: the foam core is smaller than these dimensions due to the taper of the airfoil.
Assemble the sheeting as shown using Duco cement, (my replacement for Sigment). I tape the sheeting together to dry.
Sand the sheeting and mark the inside to be glued. I also weigh the sheeting. For this wing the top skin was 19g and the bottom was 18g. My buddy Jim DeYoung always uses the following rule when sheeting: .025g of epoxy per square inch of balsa. I am using Gorilla glue but figured I would try to use the same format. In this case we have roughly 168 square inches of balsa and we should only add about 4.2 g of glue per wood surface. Therefore, my glued panels before placing the foam inside should add up to approximately 45.4g with glue. It turned out that they weighed 49 g. Based on how the panels looked for wettness of glue. Which isn't too bad and very close to what it would be had I used Epoxy.
I lightly sand the cores with 220 to remove all the fuzz. And vacuum clean, the same is done with the sheeting prior to adding glue. I keep a tack rag handy to wipe everything down before starting. I mark the top skin for preparation of glass for the aileron servo. The center of this is approximately 7" from the root and 3" from the LE. I use a single layer of 3oz cloth on the top skin as shown. This provides some support for the aileron servo as I glue it to the top skin later on.
In my case I tape the TE to form a hinge at the TE. When opened the gap between the top and bottom sheeting is approximately 1/8". I add tape to the bottom skin full length of the TE and then flip it over on my flat bench. Then add the top sheeting aligning the TE for the entire length. All the while folding the tape onto the top skin to form the hinge.
Add Gorilla glue to the inside of the skins as shown using a credit card or plastic scraper. A majority of glue is removed. The entire balsa sheeting should have glue and no dry patches. Use the above formula to figure out it if you are in the ball park. As well as the pictures below for wettness.
When sheeted the balsa sheeting with stick out past the rear side of the foam schucks (The upper and lower portions of the foam blanks). Due to the airfoil shape, I sand a taper into the last 3/8" of the bottom balsa sheeting. Basically, the TE of the bottom sheeting has zero thickness and is tapered from this zero thickness to a full 1/16" thickness 3/8" in. This allows for the top sheeting to remain a full 1/16" thick along the entire length of the TE of the finished wing. Providing the proper airfoil shape and meeting the 1/16" thick TE requirement per the rules.
The next series of photos will show how I prepare sheeting and sheet the wing.
You will need 8 pcs of 1/16" X 4" x 36" balsa to sheet a full wing. Yes you will have some scrap. I use a full width sheet along the LE, a second sheet along the TE trimmed to mate with the LE and then a wedge shape in the middle. The key to having good sheeting is making the mating surfaces square and flat. There are several ways to accomplish this. I use a sanding block and the edge of my bench. The end of my bench keeps the block square and the sheet is sanded relative to my bench. Thankfully, my bench is pretty square. I use the top of one panel to create my sheeting as this is the longest side due to the airfoil shape. It is critical that the finished wing matches the final dimensions on the plans to meet the min wing area rules. You should be shooting for 10.75" at the root and 7" at the tip. This is from the front of the foam core (NOT including the 3/16" LE to the end of the sheeting. NOTE: the foam core is smaller than these dimensions due to the taper of the airfoil.
Assemble the sheeting as shown using Duco cement, (my replacement for Sigment). I tape the sheeting together to dry.
Sand the sheeting and mark the inside to be glued. I also weigh the sheeting. For this wing the top skin was 19g and the bottom was 18g. My buddy Jim DeYoung always uses the following rule when sheeting: .025g of epoxy per square inch of balsa. I am using Gorilla glue but figured I would try to use the same format. In this case we have roughly 168 square inches of balsa and we should only add about 4.2 g of glue per wood surface. Therefore, my glued panels before placing the foam inside should add up to approximately 45.4g with glue. It turned out that they weighed 49 g. Based on how the panels looked for wettness of glue. Which isn't too bad and very close to what it would be had I used Epoxy.
I lightly sand the cores with 220 to remove all the fuzz. And vacuum clean, the same is done with the sheeting prior to adding glue. I keep a tack rag handy to wipe everything down before starting. I mark the top skin for preparation of glass for the aileron servo. The center of this is approximately 7" from the root and 3" from the LE. I use a single layer of 3oz cloth on the top skin as shown. This provides some support for the aileron servo as I glue it to the top skin later on.
In my case I tape the TE to form a hinge at the TE. When opened the gap between the top and bottom sheeting is approximately 1/8". I add tape to the bottom skin full length of the TE and then flip it over on my flat bench. Then add the top sheeting aligning the TE for the entire length. All the while folding the tape onto the top skin to form the hinge.
Add Gorilla glue to the inside of the skins as shown using a credit card or plastic scraper. A majority of glue is removed. The entire balsa sheeting should have glue and no dry patches. Use the above formula to figure out it if you are in the ball park. As well as the pictures below for wettness.
When sheeted the balsa sheeting with stick out past the rear side of the foam schucks (The upper and lower portions of the foam blanks). Due to the airfoil shape, I sand a taper into the last 3/8" of the bottom balsa sheeting. Basically, the TE of the bottom sheeting has zero thickness and is tapered from this zero thickness to a full 1/16" thickness 3/8" in. This allows for the top sheeting to remain a full 1/16" thick along the entire length of the TE of the finished wing. Providing the proper airfoil shape and meeting the 1/16" thick TE requirement per the rules.
- Attachments
-
- Note: The finished core at the root, with sheeting but not including the LE balsa is roughly 10.75". I need to make sure my sheeting is assembled to accomplish this dimension.
-
- Note: The finished core at the tip, with sheeting but not including the LE balsa is roughly 7". I need to make sure my sheeting is assembled to accomplish this dimension.
-
- The bottom sheeting is tapered for the last .375" at the TE. This allows the top sheeting to remain 1/16" thick along the TE and the bottom basically zero or near zero for a finished TE thickness of 1/16" per the rules. This 3/8" dimension is also used to position the foam core while assembling the sheeting to the core.
-
- Mark the root to 10.125"
-
- Mark the tip to 6.5"
-
- Use a straight edge to connect these two marks to trim the TE of the core, removing the material too thin to manage.
-
- I use scissors for this process as it is easier than trying to cut with a knife and having the TE tear.
-
- This is what the sheeting looks like prior to assembly. Full width along the LE. TE sheet has a small triangle removed at the tip and the center section has a wedge installed.
-
- Normally, I would use Sigment to glue my sheeting together but it has been discontinued. I have switched to Duco Cement
-
- Keeping the gaps to a minimum. Tape the sheeting together forming a hinge. This allows you to flex the sheets and expose the butt ends for gluing. With the sheets flexed add glue and flatten the sheets. Wipe excess glue off with a paper towel and add tape to the surface to keep the sheets flat while drying.
-
- I glue the small triangle first then tackle the entire length of the LE balsa sheet.
-
- Final view of sheeting. I remove all tape after it has dried to sand and mark which side I want to be the inside. However, while using Gorilla glue I have learned that if I have small gaps the glue expands out into the schucks. Therefore, I re-tape the top side prior to glueing the sheeting down.
-
- This shows where the glass will be applied to support the aileron servo
-
- Add glue and spread evenly across the balsa.
-
- This is wetted but not too wet and not too dry.
-
- Final weight of both top and bottom skins with glue is 49 g.
-
- Wipe the foam core with a damp paper towel. Water provides the dampness. Seems to help the Gorilla glue kick. DO NOT wipe the balsa. Just wipe the foam with the damp paper towel.
-
- Install the foam core into the balsa skins making sure your root and tip dimensions are as expected per the plans.
-
- Place the core and sheeting assy into the schucks and tape the ends to keep everything from moving around.
-
- Tape the LE to and TE to keep the schucks in place. Sight down the LE and TE and make sure you have not introduced a bow during taping. Keep the core aligned to the schuck and set aside to be weighted.
-
- Put the foam assemblies on a flat surface and apply weight to the top side as shown.
Last edited by kane on Wed Feb 07, 2024 10:53 am, edited 2 times in total.
Re: EF-1 Foam wing sheeting (DK Rickey Rat/Miss DARA)
Wing cont:
Someone had asked to clarify the taper I add to the bottom sheeting at the TE. I have included pictures of the actual part as well as a small detail from the plans. Hope this helps.
Someone had asked to clarify the taper I add to the bottom sheeting at the TE. I have included pictures of the actual part as well as a small detail from the plans. Hope this helps.
- Attachments
-
- The area marked off will be cut/trimmed/sanded on an angle. At the extreme TE it is very thin and angles upward from that point to the normal 1/16".
-
Re: EF-1 Foam wing sheeting (DK Rickey Rat/Miss DARA)
Wing cont:
After the wing sheeting has dried, I trim and sand the wing in preparation of the LE, tips and Aileron hinge line.
First assemble the tips. I use 3 pcs of 3/16" balsa sandwiched with a layer of 1/16" balsa. The order is one pc of 3/16" then 1/16" and finally two layers on top. When assembling be sure to make a left and right assembly. Two layers on top due to the airfoil shape. I use the 1/16" in the center to align the block and keep everything straight.
I use Duco cement to create the tip assemblies. I use Titebond to glue the balsa parts to the foam wing blank.
My trimmed panel prior to adding any additional balsa weighed 68g.
After the wing sheeting has dried, I trim and sand the wing in preparation of the LE, tips and Aileron hinge line.
First assemble the tips. I use 3 pcs of 3/16" balsa sandwiched with a layer of 1/16" balsa. The order is one pc of 3/16" then 1/16" and finally two layers on top. When assembling be sure to make a left and right assembly. Two layers on top due to the airfoil shape. I use the 1/16" in the center to align the block and keep everything straight.
I use Duco cement to create the tip assemblies. I use Titebond to glue the balsa parts to the foam wing blank.
My trimmed panel prior to adding any additional balsa weighed 68g.
- Attachments
-
- Assemble a left and right wing tip using 2 pcs of 3/16" for the top a pc of 1/16" for the center and finally a pc of 3/16" for the bottom. I use Duco cement for this and clamp the assemblies together to dry. Keep all the parts aligned during the drying process.
-
- The center layer of 1/16" balsa is an alignment tool. This allows you to make sure the tip is straight and true relative to the TE and LE.
-
- Center mark for alignment.
-
- This is a cleaned up foam blank the excess balsa from the LE and tips is removed. and the TE is lightly sanded to remove any glue residue. Stay true to the root and tip dimensions for area purposes.
-
- I use Titebond to glue all balsa to foam.
-
- Apply glue to both the tip block and foam wing. Align the marks on the TE to the TE of the wing. PRIOR to gluing ensure the tip block and foam core are square and sand as necessary.
-
- Align the center of the tip block with the centerline of the LE. Tape the tip in place and double check the TE.
-
- Sight down the TE and LE to make sure the tip block is square and true to your wing panel.
-
- Cut the 3/16" x 1/2" x 36" balsa to the proper length for the LE. Note the balsa LE overlaps the tip block. Use Titebond to glue the LE in place and tape to secure.
-
- Once the LE and Tips have had some time to dry. I mark the bottom skin to receive the aileron hinge material. Follow the plans for the location. Early versions of this model had ailerons in excess of 11" in span and new versions are closer to 9". The longer versions were extremely sensitive, the 9" version is very normal now for pylon racers.
-
- The hinge line is made of two layers of 3/16" balsa. I use the excess 1/2" stock cut from the LE material. I always, extend my hinge line beyond the end cuts of the aileron as noted here.
- EF1 Aileron hinge.JPG (22.17 KiB) Viewed 2976 times
-
- Using an X-Acto knife cut away the bottom sheeting through the foam but not through the top skin. And remove the balsa sheeting in this area.
-
- Using a small common screwdriver remove the foam up to the top skin.
-
- Install a pc of 3/16" balsa as shown and trace against the wing panel to identify the proper thickness for the LE of the hinge line. Cut the balsa along your mark and the second pc will be your rear portion of the hinge line. Trial fit both pcs prior to adding glue. If necessary trim/sand to fit. If your second pc is too narrow, use some scrap 3/16" to make a new part.
-
- Add Titebond to the opening.
-
- Add Titebond to the 3/16" part where it meets the foam. I DO NOT GLUE THE TWO BALSA BLOCKS TOGETHER. By not gluing them together when cutting the aileron free, you have a nice guide for your X-Acto knife to cut the top sheeting along the hinge line.
-
- Done set aside to dry.