"BA LSA FREE" C/L RA CIN G W IN G S or "a different approach to m ake a w ing using a m ould and (alm ost)no balsa" by Enrico M A U LETT I Jan - 2001 1 st PA RT TH E M O U LD (first part - upper m ould) "Balsa free" w ing m eans (for m e)a glassed foam w ing m ade using tw o devices: - a tw o parts m ould - a sim ple vacuum bagging system . In m y opinion,there are severalreasons to think about a "balsa free" w ing: 1. Possibility to reach alw ays the sam e result: 1.1. Profile:if the m ould is O K,then allthe m oulded w ing w illbe O K 1.2. W eight:using "constant density" m aterials as foam and fibre glass,it w illbe possible to have (alm ost)the sam e w eight 1.3. S tiffness:using "constant properties" m aterials and a standardised procedure,the finalresult w illbe alw ays the sam e 2. Possibility to reduce w orking tim e (accepting to spend tim e in the m ould preparation) 3. Possibility to avoid balsa dust … and lot of "sanding hours" M y finalw eight target for a S T R w ing is som ething around 80÷85 g (w ithout internalbellcrank and lead-outs)… here after I'll explain w hy I think this is possible: A bout glassed foam w ing and vacuum bagging: I read a lot on Internet about how to produce foam glassed w ing for different type of m odelglider … these inform ation I collected convinced m e that it's possible to follow a sim ilar m ethod for C/L racing w ing too … so I decided to have a go! (one of the m ore sophisticated, but really interesting w eb page: http://w w w .delago.de/ariane/EH om e.htm ) H ere after,a section of the m ould,the fibre glass clothes and the foam sheet during the construction (of course the sam e job has to be done for both the m oulds). wing surface [dm^2] 12 fibre-glass cloth [g/m^2] 42 no. fibre-glass cloth layers (upper and lower wing surface) 2 total fibre-glass weight [g] 20.16 carbon rowing (leading edge) [g] 10 ? foam density [g/dm^3] 30 average foam tickness [mm] 4 foam weight [g] 14.4 epoxy resin [g] 40 ? TOTAL WEIGHT [g] 84.56 WEIGHT DISTRIBUTION
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"BALSA FREE" C/L RACIN G W IN GSor "a different approach to make a wing using a mould and (almost) no balsa"
by Enrico M AULETTI Jan - 2001
1st PART
THE M O ULD(first part - upper mould)
"Balsa free" wing means (for me) a glassed foam wing made using two devices:
- a two parts mould
- a simple vacuum bagging system.
In my opinion, there are several reasons to think about a "balsa free" wing:
1. Possibility to reach always the same result:
1.1. Profile: if the mould is O K, then all the moulded wing will be O K
1.2. W eight: using "constant density" materials as foam and fibre glass, it will be possible to have (almost) the same
weight
1.3. Stiffness: using "constant properties" materials and a standardised procedure, the final result will be always
the same
2. Possibility to reduce working time (accepting to spend time in the mould preparation)
3. Possibility to avoid balsa dust … and lot of "sanding hours"
M y final weight target for a STR wing is something around 80÷85 g (without internal bellcrank and lead-outs) … here after I'll
explain why I think this is possible:
About glassed foam wing and vacuum bagging: I read a lot on Internet about how to produce foam glassed wing for different
type of model glider … these information I collected convinced me that it's possible to follow a similar method for C/L racing
wing too … so I decided to have a go! (one of the more sophisticated, but really interesting web page:
http://www.delago.de/ariane/EHome.htm)
Here after, a section of the mould, the fibre glass clothes and the foam sheet during the construction (of course the same job