Dirty Birdy .60 - original balsa kit build
 

I followed a tip from an RCC member last year to the Winnipeg Kijiji site and bought a NIB original Birdi Enterprise Dirty Birdy .60 kit. I've was thinking about what I was going to use to power this thing and then OS announced the new GGT15. A gasoline fueled .90 size two stroke that uses a glow plug! I have a bit of a weather break in the Comp-Arf rebuild that I am doing so I dug the kit out of the closet today and got started on the tail section.

The horizontal stab. goes together pretty quickly and the fin/rudder is solid 3/8 sheet. The balsa in the kit is, for the most part, very good but the material supplied for the elevators was ridiculously heavy! I replaced them with some light balsa from my stock and saved 1.3 ounces. Same with the rudder - I replaced the supplied part and saved another 1/2 ounce. 1.8 ounces saved from the end of a long tail might save 7 to 8 ounces of lead in the nose...

I did a little mod on the horizontal stab. tips. I set up a fence on the band saw and cut the 1/2" thick blocks (nice and light :)) in half. I laminated a piece of 1/32" plywood in the middle of the block. This gives me a visual reference when shaping the tips as well as toughening up the outer edge of the tip against hanger rash. I drilled some holes in the ply before gluing them back together so very little weight gain.

Re: Dirty Birdy .60 - original balsa kit build
 

im in :):)

Re: Dirty Birdy .60 - original balsa kit build
 

I'm as well.... I'm soon to start my own retro pattern plane build circa 1962.

D.

Re: Dirty Birdy .60 - original balsa kit build
 

Cool!, Thanks for following along!

Finished up the horizontal stab and elevator. Threw the finished items on the scale and was surprised that they only total 4.1 ounces :) Not bad when the kit supplied elevators weighed 2.8 ounces just by themselves...

It seems I've caught a mild case of Brumitis and the only cure is to obsessively
weigh parts and figure out ways to make them lighter :biggrin:

The fin and rudder are 3/8" thick slabs of balsa and since I'm going to be covering with monokote I thought why not take a bit off. Using the dremel and a router attachment I opened up a few spots (1/8th inch deep) on both sides of the fin. Saved a 10th of an ounce :rofl:

Re: Dirty Birdy .60 - original balsa kit build
 

The fuselage is built upside down on top of another 3/8" balsa block! The wood itself was good and light but I took the opportunity to mill another half ounce out of the airframe. A total of about 2.5 ounces (all behind the CG) can't hurt! Another evening and I'll have the fuselage framed up :)

Re: Dirty Birdy .60 - original balsa kit build
 

I'm in as well! This was the last plane I built before my 20 year plus break from the hobby. I had a HP gold cup in it on a pipe, so much fun!! Wish I still had it!

P.S. your bench cover looks a little fishy!!

Re: Dirty Birdy .60 - original balsa kit build
 

hi Gordon,

What tools did you use to lighten the top fuselage block?....... I'm guessing a router bit in a drill press.

Nice build and lightening methods....... there is a fellow - Tom Clark - in the U.S. whose methods of lightening the fuselage are pretty radical and he used this with multiple larger models..... here is a link to his build thread of a 78" wingspan Chaos powered by a ST 2300 that has an all up weight of 8 pounds.....

http://www.rcgroups.com/forums/showthread.php?t=2350076

good luck on your build,

Re: Dirty Birdy .60 - original balsa kit build
 

When you make lightening holes why aren't you going all the way through?

Re: Dirty Birdy .60 - original balsa kit build
 

Thanks for the link, I'll take a look. I'm using a dremel tool with a router head attachment. It works well for balsa.

Hi Mike, on the fin I wanted to preserve some of the strength that the webbing gives and on the fuse I wanted to preserve the look of the original on the outside. I'm not too concerned with ending up in the crazy light range. I just wanted to pull out unnecessary weight without affecting airframe strength. :)

Re: Dirty Birdy .60 - original balsa kit build
 

Spent an hour getting everything ready to glue in the hardwood engine rails and the #1 former. The instructions very wisely suggest that you do a dry run through first and THEN apply the epoxy and clamp everything in place for real. This is a really old school design with 10.5 inch hardwood engine rails that run back to the #2 former (where the wing dowels insert). The OS GGT15 is about a 1/4 inch wider than the stock design so I had to trim a bit off with the band saw before gluing them in place.

Also glued on the balsa fuselage bottom plate. Lots of weight keeps everything flat and true while the glue sets up.