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#wing

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TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

How to remove/demold a part from a fragile part. (Hint: You can create shear in more than one way, and it may be better than creating a peeling action with hammer and chisel.)

The blue Styrofoam that served as the form will be destroyed as it's removed from the fiberglass wingtip weel, but it's a one-off form/mold that lacked any taper.

(This is a follow up to universeodon.com/@KrajciTom/11 )

#avgeek #aviation #ElectricAircraft #ExperimentalAviation #homebuilt
#Glider #DIY #Wing #Epoxy #Fiberglass #Composite #Shear #Peel

No! You risk damaging the wing's surface this way. (OK, you could use a plastic/rubber wedge, but let's try a finesse method first...)
The long clamp squeezes on both ends of the fiberglass part...never touching the wing. This squeeze causes the base of the fiberglass part to bow outwards...shearing along the surface of the wing.
Only light force was applied to tighten the clamp...and the part easily popped off.
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TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

Making a custom wingtip wheel for my glider's right wing.

The bottom of the wingtip was covered with clear packing tape, then lightly waxed.

Hot glue temporarily attached the blue Styrofoam mold/form, which also contains the 60mm diameter roller blade wheel.

The part is made from seven plies of 7725 weave fiberglass that will be cut into a triangular shape after wetting with epoxy.

No vacuum bag, so this is a hand lay up. I had to use some small pieces of metal to coax the fiberglass to stay in the correct place.

The garage will be heated overnight so that the part cures, then some tugging and a rubber mallet should separate the part.

#avgeek #aviation #ElectricAircraft #ExperimentalAviation #homebuilt
#Glider #DIY #Wing #Epoxy #Fiberglass #Composite

The underside of the wing tip has been covered in clear packing tape, then waxed.
This is one ply of dry fiberglass, colored white, laying over a piece of green plastic sheet. Faintly visible through the fiberglass is a triangular pattern. After wetting seven plies, I will cut the fabric to that triangular shape. That shape will drape over the form and make the part in one step. The two edges of the open triangle will join and overlap along the trailing edge of the part, aft of the wheel.
Wetted fiberglass has a green tint. Scrap metal helps hold the fabric in the correct location. Strips of light brown fabric are Teflon coated fiberglass, which serves as peel ply. I'm using it to also help coax the fiberglass into the desired shape.
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TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

Discovering and fixing a small mechanical interference in the spoilers.

The spoiler cap, in some places, wasn't fitting into the recess in the wing properly.

Why?

1st photo - spoiler is halfway retracted into the wing. One of the parallelogram arms is at a 45 deg angle. You can see that I have already removed some semicircular sections in the upper spoiler paddle to avoid parts colliding as the spoiler closes.

2nd - looking directly up into the spoiler paddle. There are spring loaded bolts to hold the spoiler cap. This particular bolt is rather close to a parallelogram arm...

3rd - ...especially when the arm is swinging more as the spoiler is almost fully closed.

4th - That telltale dimple on the parallelogram arm tells me everything. The bolt is a little bit too long.

A Dremel and cutting wheel removed 2mm of bolt.

Problem solved!

#avgeek #aviation #ElectricAircraft #ExperimentalAviation #homebuilt
#Glider #DIY #Wing #Spoiler #Parallelogram #Geometry #Interference #Dremel

A view of the back side of the upper spoiler paddle (carbon fiber, black) as the spoiler is halfway closed into the wing. One of the grey round steel parallelogram arms has swung to a 45 degree angle. (The arm will swing much further as the spoilers fully close.)
Looking vertically up into the spoiler paddle. One of the spring loaded spoiler cap retaining bolts (shiny, plated metal) is visible. The upper end of the darker gray parallelogram arm is also visible in the right half of the photo. The spoiler is fully open because the parallelogram arm is vertical.
The spoiler is almost fully closed in this closeup view. The gray parallelogram arm has swung through more than 60 degrees from vertical. The arm is getting close to the end of the bolt. (Only the very tip of the bolt is visible from behind the aft lip of the spoiler paddle.)
This dimple in the gray steel parallelogram arm is definitive proof that it is colliding with the bolt. Shortening the bolt solves the problem.
Public
TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

Checking the fit of the spoiler cap into the glider wing. (I need to do more sanding of the beveled edges because it sits a little bit high.)

The typical glider spoiler is mounted on a swinging parallelogram, and is controlled by a push-pull tube. It also features an over center lock, which was not activated in this video.

Note that the lower spoiler paddle is not installed at the moment. When it is, it produces a complete wall to the local airflow over the top of the wing. That is how we control descent angle during final approach to land.

#avgeek #aviation #ElectricAircraft #ExperimentalAviation #homebuilt
#Glider #DIY #Wing #Spoiler #Parallelogram #Geometry

Public
TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

Making a fiberglass wingtip wheel for the glider wing.

1st photo - making the mold/form out of foam, with a 60mm diameter inline skate wheel in place. Note that the underside of the wing is covered with clear tape to protect it from epoxy when I lay up 7 plies of glass.

2nd photo - making the fabric template. A single piece of glass fabric (weave 7725 because it drapes so well over various curves and corners) will make the final part, but there will be an overlap along the trailing edge. I draped a piece of plastic over the foam form after it was hot-glued to the wing and then traced out the pattern, with some reference marks such as a center line.

3rd - Demolding the cured part by squeezing it so that it flexes/distorts a bit...and the epoxy at the base easily shears off from the waxed clear tape. (No need for hammer and wedges.)

4th - rough sanded final part.

#avgeek #aviation #ElectricAircraft #ExperimentalAviation #homebuilt
#Glider #DIY #Wing #Fiberglass #Epoxy #Composite

Blue Styrofoam is attached to the underside of the glider wingtip. The foam is easy to sand and shape to the desired contour. Unfortunately, such a mold is single-use becuase I did not add any taper to the part, so I had to tear the foam out with pliers after the fiberglass cured. No worries, I have paper templates in order to quickly make a second form for the other wing.
A template for the fiberglass fabric. This wingtip wheel is a single-layup operation. Note that while the leading edge will be a continuous piece of fabric, but the trailing edge will have the two ends overlap.
Demolding a part *should* be an easy matter...if you set things up correctly...good geometry in the mold, proper use of release wax, etc.
Final part after rough sanding to remove the outer weave pattern. It will get a proper trimming job later, then painted white.
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