Weight and balance question

Hi guys, simple question. I am doing a fresh w&b on my rv6 i bought last month. The plans call for the fuselage to be leveled by the longerons in the cockpit area at the datum line which is the cockpit rails per page 14-2. Is this referring to the cockpit rails over the armrest or the forward section where the canopy shocks are attached. It seems like the plane is really tail high when using the rails over the armrest and looks more level when using the more forward section. I have a hollow crank, o-320, catto 3 blade prop, simple steam gauges and the plane is coming out extremely tail heavy using the forward rail section that looks more level. Using the cockpit rails over the armrest would really help shift the numbers forward.

Thanks
Hank

The leveling point is the canopy rails over the arm rests. Not the forward portion.

Perfect. It just looked weird with the tail so high. Thanks Mel.

I believe it is supposed to be leveled across both the lateral and longitudinal axis. I am not sure how critical the former is, but I believe that plans called for that.

Larry

Don't forget to close the canopy. An open tip-up will shift the CG forward and an open slider will shift it aft.

Here is what i got using a set of digital race car scales and leveling with the canopy rails.

Left 496
Right 493
Tail 75

Total 1064

Empty cg 71.8"

This still seems about 5 lbs heavy on the tail and 1" further aft than most other -6 that i have read about. I was wondering if these numbers are in the ballpark? I can carry a passenger or cargo, but not both.

My -6, tip up, 0-320 b2b, hollow crank, bendix mags, carb, catto 3 blade prop, pc 680 battery behind firewall, smoking planes 4.5 gal smoke system, 20 lbs sabre crush plate, standard steam gauge panel, painted interior, basic seats, api 6" tailwheel and thicker metal on tail feathers.

There is nothing in the tail except strobe driver box and elt. I think the cg is about as good as i can get without going to a cs prop.

titanhank said:

Here is what i got using a set of digital race car scales and leveling with the canopy rails.

Left 496
Right 493
Tail 75

Total 1064

Empty cg 71.8"

This still seems about 5 lbs heavy on the tail and 1" further aft than most other -6 that i have read about. I was wondering if these numbers are in the ballpark? I can carry a passenger or cargo, but not both.

My -6, tip up, 0-320 b2b, hollow crank, bendix mags, carb, catto 3 blade prop, pc 680 battery behind firewall, smoking planes 4.5 gal smoke system, 20 lbs sabre crush plate, standard steam gauge panel, painted interior, basic seats, api 6" tailwheel and thicker metal on tail feathers.

There is nothing in the tail except strobe driver box and elt. I think the cg is about as good as i can get without going to a cs prop.

Click to expand...

A few things you can do:

1) Relocate the ELT to the space right behind the battery in the footwell (that's where it is on my airplane).
2) Relocate the strobe box to the sub-panel (again, where mine is).
3) Remove the smoke system, assuming it is located in the baggage compartment.

FYI, my airplane's empty CG is just forward of 71" with an O-320 D2J, a composite prop, and a 9 lb flywheel weight. The airplane weighs 1031 LB.

With careful positioning of stuff, I can carry 350 lbs of people and a 110 lbs of stuff, and don't get into an aft CG condition until I have about 7 gallons of fuel remaining. The gross weight on my airplane is 1675#, so I can launch with ~31 gallons of fuel, loaded as described. That gives me 3 hours of range, which is plenty for most trips. Offload 40 or so pounds of baggage and I can go full tanks and another hour on fuel.