I have been glassing the tail parts on my gliders lately and wanted to share a few reasons why I like to do so and an easy inexspensive way to do it.
The reasons are all quite simple, stiffer parts, more consistent launches due to less flexing upon release and less warping caused from atmospheric or weather conditions. I am not sure of this last thought of wether thinner is better but you can reduce balsa size but increase rigidity possibly creating less drag. It may not be as efficient though? I would love to hear comments on that theory.
With a bit of practice the weight gain is very minimal considering there is no need to apply any kind of waterproofing finish.
There are better ways to vacuum bag stabs but this is an inexpensive way with readily available supplies. There are many different ways to glass a stab so try some experimenting and let us all know what you learn!
Supplies-
1) Write on wipe off board just like shown at this site.
http://www.misterart.com/g8559/Carolina-Pad-Write-On-Wipe-Off-Poster-Board.htm&n...; They are available online, through Ebay, or from a local Michael's craft store. It is important to hand pick what you buy unless buying online because the sheets dent and crease easily. Any dents or imperfections will be transfered to your stab.
2) Ziploc vacuum pump with gallon sized vacuum bags just like this
http://www.foodnetworkfans.com/forum/kitchen-gear-appliances/5540-ziplock-has-va...You can find these at fredmeyer or many other grocery store for about 5$ When sealing the bag I like to use a strip of packaging tape to double seal the actual zipper by just taping the top of the bag shut. Make sure you don't touch the little flap valve seal at all or it will not function as well.
3) You will also need some pure carnuba car wax or other proven release agent to apply to the write on wipe off carrier. I use Mothers pure carnuba wax.
4) sharp scissors and or a rotary cutter and mat, some kind of roller be it a wall paper roller or smooth glass jar, paper towels, mixing bowl, a phone book or two, and some good laminating resin with a decent potlife. I like Pro-Set as it becomes very crisp, I like to use .6oz. glass I think the lighter the better. sig sells some 3/4oz. glass at hobby shops but it is folded so I suggest getting it in a roll. You will also need some 10 mil painters plastic or equivalent to wet out your glass and to cover yours parts with inside the bag.
To start shape your tail parts from balsa using a template that you will also use to trace an outline 1/32" oversized onto the dull side of your write on wipe off sheet (aka mylar) before you cut out the mylar wax it on the shiny side with one coat of carnuba then let dry for 20min. then apply another heavy coat then immediatley start to polish till the wax seems to dissapear and the mylar is very slick and shiny. This is your finish that will appear on the stab so make it perfect! Waxing before you cut helps minimize any accidental creasing or folding of the mylar. Then cut out and set aside.
Roll out enough platic to cover you work spcae or your cutting mat, then place the mylars waxed side up on the plastic. Roll out you glass on a 45degree bias to the tail parts then with your scissors cut off the chunk big enough to cover all your parts and let it lay on the mylar over the palstic.
Next wet out your glass covered mylar parts with epoxy using either a roller, foam brush or a saturated paper towel wearing gloves. Once wetted out fold up a paper towel into a square and blot out the excess epoxy off each mylar using one side of the paper towel for each mylar( refold the paper towel to a fresh side for each mylar) Then take a fresh paper towel and cut it in half hot dog way. Place the fresh paper towel down on the wet glass and roll it with your roller to soak up any extra epoxy then repeat with fresh paper towels for each mylar. Do this only once so that the skin does not become too dry.
Once finished, using the rotary cutter cut around the mylar an 1/8" or more ovwersized from the outline cutting through the painters plastic. toss all the waste then peel off the painters plastic from the back of the mylar, accurately place your tail parts onto the glass side up mylars then cover with the other half. Tape the mylars together to ensure they do not move while in the bag.
Then place into the ziploc bag, you can also place the mylars into a painters plastic envelope then place into the bag but it is not needed. The excess thickness of the painters palstic envelope makes it harder for the vacuum bag to suck tight around the outline of your stab which is important. The ziploc bag has it's own built in breather side of the bag so no need for an additional breather. Seal the bag and pump out the air as hard as you can. After making sure everything looks good tape shut the zipper end with clear packaging tape then pull vacuum again.
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