Here's a Few
I've been trying to save weight wherever possible on my RV-6 build and will share a few of the things I did. Now, I have a running bet with a few guys on what my empty weight will be, so you'll notice some of these get increasingly maniacal. I'll spare you the full on weight-psycho stuff until I weigh in and either have to use it or not.
A lot of people mention the wood prop saving 25-30 lbs, but then go and put a 18lb crush plate on the nose for CG reasons
With that in mind, I focused my weight savings at the tail. Ideally allowing me to run a composite prop without a weight up front.
Starting at the tail:
-Using the classic RV-6 VS and rudder (no counterbalance) (sorry 7/8/9 builders, not an option).
-Built a new set of .016 elevator skins using RV-7 counter balance arms which are longer, and position the CW horizontally, thus requiring less counterweight. (The combination of elevator counterweight and skins will be nearly a 2lb reduction alone)
-Turned a titanium tailspring on the lathe (1lb saved).
-Planning to do a billet tailwheel fork and Ti axle.
-Scallop the mating flange of the fairings and pop rivet instead of screw on.
-MS-21042 instead of AN-365's
-Round and taper those corners on your 1/8" angles and straps in the tail.
I'm hoping that by pulling 4-5lbs out of the aft-most point on the aircraft, I'm able to run a ground-adjustable composite prop without any extra weight up front (saving another 10-15lbs). Engine is a carb'd O-320.
Then of course are all the easy ones throughout the rest of the aircraft:
-Build a taildragger
-MS-21042's instead of AN-365's
-Minimal interior
-Single EFIS Glass Panel with LRU's mounted as close to power/data hub as possible.
-Careful and efficient wiring throughout (See AC-43.13B for calcs and help on minimizing wire size).
-Fuses instead of circuit breakers
-Single (or double) set of seat back hinges. Single seat back angle per side on the cross bar (speaking of which, lighten that piece of angle up!)
-Lithium battery (Easy 10lb saved compared to an Odyssey, 20lb lighter than a concord).
-Aluminum battery box (see RV-14 battery box if using an odyssey).
-Aluminum hard lines instead of rubber hose wherever feasible.
-Single set of brakes. (And throw those master cylinders in the lathe or mill to get rid of all the extruded material between the ports.)
Sometimes I ask myself if it's worth it... However, flying a heavy and lightweight RV back to back often reminds me that it is not in vain.