Tuesday, May 1, 2012

Ch 4: The Firewall...Do We Really Have to Call it That?

     OK...momentum really re-building now.  I'm not getting work done every day by any means but I am spending some time Friday - Sunday at least.  The last two weekends I've jumped back and built (Chap 4) and installed (Chap 6) the lower firewall.  I held off on doing this earlier because I hadn't decided what to do about the infamous spinning screws in the firewall.  I finally decided to go with Click Bond studs for the rudder pulley brackets.  Since they install on the outside vice through the firewall, I don't have to worry about installing them for a while down the road.  If your not familiar with Click Bonds yet, see Infinity Aerospace for purchase and the Cozy Girrrls website for instructions on installation (look for the Click Bond link on the left side).

I cut out and glassed the lower firewall mostly per plans as well as the parts for the two rectangular sides.

TIP:  I say mostly per plans because I did enlarge the 1"x1" aluminum engine mounting hard-points to 1.5"x1.5".  Several builders have reported not having much margin to account for motor mount tolerances so enlarging the mounting locations provide a little more margin.

TIP:  Wait to cut out the longeron cutouts or the electrical conduit holes in the firewall until after you've established the true positions during Ch 6. using the fake firewall.  You can be somewhat loose cutting the longeron holes in the fake firewall until you get everything line up the way you want it.  Once situated, I glued popsicle sticks on the fake firewall around the edge of the longerons to form template I could use to mark a starting point for the cutouts in the real firewall.  Of course some minor adjustments were made as I fitted the real firewall but it worked out pretty well.

I'm waiting to cut out the top firewall because I haven't decided whether to make it wider and taller, ala Aerocanard, or not.   Al Aldrich from Aerocad was nice enough to send me .pdf files of the M-Drawing that has the Aerocanard firewall.  If I decide to go taller/wider, I can use that template and then be able to buy the pre-fab Aerocanard upper cowling to fit.  I've got a while to decide on this.  In the mean time, I need to sit in the back of a few different Cozy's to see how they feel.  I think I like to look of the standard turtleback better but builders have said the wider/taller turtleback offers much more headroom comfort for any back passengers.  Some builders have raised and widened the front but tapered it back to the standard firewall shape.  Much research to do still.


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