LET’S TALK
GIANT SCALE
BY JOHN GLEZELLIS
Making Modifications
“Measure twice, cut once” are words to live (and install) by
Installing an
internal exhaust
system is a
common airframe
modification.
AS I AM WRITING THIS COLUMN, I am
finishing up a 40% Thunder Tiger Extra
260. I decided to use the Desert Aircraft
DA-170 engine for this model, and for
added performance, I chose the included
KS 1090 tuned pipes. If you are new to the
world of giant-scale aerobatic models, I
strongly urge you to look at different
exhaust types that your engine manufacturer recommends. For Desert Aircraft (or
similar) engines, many options exist. Personally, I love the KS 1090 pipes for both
the DA-150 and DA-170 engines. Since the
Thunder Tiger Extra 260 is designed for the
use of canister exhaust and mufflers, I will
show you how I installed my internal
tuned exhaust and how to seal off the
tuned-pipe area from the rest of the fuselage interior.
Since the Extra 260 is designed for both
muffler and canister use, it already has a
pipe tunnel installed to accept exhaust can-
isters. Due to the fact that I installed tuned
pipes, I needed to make a few modifications. Here are the tools needed for this
modification:
• hobby knife
• sanding block with 80-grit sandpaper
• cardstock paper
• pencil
• graph paper
• ⁄8-inch lite-ply
1
• adhesives
ENGINE AND HEADERS
Before you begin your exhaust tunnel modification, you must first install the engine
and the exhaust headers so you can properly determine the length of the final pipe
tunnel. On this airplane, you have to install
the firewall. After I determined where the
firewall would be positioned on the engine
box, I aligned it so there was no up or down
engine thrust. I also built in a slight amount
of right thrust and used 30-minute epoxy to
As you can see, the KS 1090 tuned pipe is much longer than your typical canister for both the DA 150 and
170 engine.
