Empty Weight and Center of Gravity

Hi,

Anyone out there that can provide us with the empty weight and C of G
of thier RV-8 that matches or closely matches our aircraft.We need this
info to decide by calculation the best position for the battery.Please provide
details on position(aft of datum)and type of battery in your aircraft.

Details of our aircraft (RV-8)
-Lycomming IO360M1B horizontal induction
-Hartzell blended airfoil constant speed prop
-Slick mags
-MGL Odessey with backup battery(no backup steam gauges)
-Transponder
-No Lights
-No Autopilot
-Vetterman stainless exhaust

Thanks,


Andre & Nico Burger
South Africa

1112 lbs and 77.77 inches!

With rear Oddyssey PC680, Superior IO360, Hartzell 4797 blended aerofoil prop, Vetterman exhaust, Dynon 180, lights and transponder, with paint and interior, plus oil and unusable fuel

weight 1112lbs
CG 77.77 inches
moment 86484

Fine for solo flight just crusing around perhaps the odd aileron or barrel roll. For anything more energetic I put some ballast in the rear baggage compartment.

Hope that helps.

Chris

similar RV-8 wt and cg

Chris's airplane described above has a lighter engine by about 25-30 lbs.

My RV-8 has an angle-valve IO-360-A1A engine, should be close to yours.
I have a Whirl Wind prop, which is a fair bit lighter ( I think 17 lb).

I have Concorde RG-25 battery in back, and ELT and strobe power box in back too. Roll servo close to the c.g., paint, interior, lights, transponder all typical.

My empty wt is 1137 and c.g. at 79.8"

1122 lbs and 78.75 inches

Aircraft has IO-360M1B with Hartzell blended airfoil prop.
Glass cockpit.
Rear mount Odyssey + small aux battery (~5 lbs)

Takeoff CG location with full fuel and 210 lb pilot is 80.7 inches.
CG range is 78.7 to 86.82

RV-8 Battery location

PUT THE BATTERY IN THE BACK!
Over.

As Danny says... Battery in the back! The 180HP IO engine + Hartzell + Fwd Battery can leave you out of Fwd CG limit when fliying solo - and even close to the Fwd CG limit is not as pleasant to fly/land as with CG further back.

XP-IO-360 + F7496 Hartzell
PC-680 in rear
Basic figures: 1106lb / 78.59"

A good rule of thumb is you want the flying CG to be at/aft of 80" if you can...

Andy
RV-8 G-HILZ

Andy Hill said:

A good rule of thumb is you want the flying CG to be at/aft of 80" if you can...

Andy
RV-8 G-HILZ

Click to expand...

Very good advice, Andy. I fly solo aerobatics regularly at about 80.6 inches and this is ideal for me. Spins are easily entered (and exited!) and the elevator is light but not touchy. I can easily trim to 75 knots on final at that CG.

Empty weight: 1124 lb.
Empty CG: 79.41"

IO-360 parallel valve, Whirlwind 200RV, one Odyssey PC625 in back and one to right of pilot's right rudder pedal.

RV-8 Battery location

OK, did the math and the Odyssey PC680 is going in the back. (How did you know that Danny )

Thanks for the numbers.

Battery Location (How did I know?)

Experience.

I built the Doll, and have flown her nearly 1200 hours. I've also flown 12 other RV-8s. If you use the Lycoming 0360 series engine, or any of its clones, and then put a 53 pound Hartzell prop on the front, you had better put the battery in the back!

I visit Jay Pratt of RV Central from time to time, and Jay will tell you the same thing. The battery goes in the back. He has finished and flown around 30 RVs now, and he knows what he is talking about!

I am willing to bet that you will fly your new 8 by yourself 90+% of the time through out its life. The 10% of the time that you have a passenger is not what you want to build for. Putting the battery in the back will make your 8 fly much better solo. (Visit the thread, Aft CG for landing the RV-8)

The only factor that will be affected is what I call the "Bubba factor". The Doll can carry a 250 pound passenger. That's a big bubba. If I had used the parallel valve engine instead of the heaver angle valve I0360, my max bubba might be 220 pounds. Of course you still have the forward cargo compartment to add blast in, if you have a big bubba and a lighter engine than I do.

I use the same logic when discussing side by side vs. tandem. Never build for the passenger. Build the plane you want, and let the passenger sit in the other seat. That seat will be empty most of the time!

Angle valve + CS prop = battery in back, and with a PC 680, that means as far back as you can get it... like right at the LE of the stab!

The bird I fly is angle valve/Hartzel BA prop/glass cockpit with a big Concord battery in the standard aft location. It's 1162/78.4 empty.

I just weighed mine yesterday for the first time, it came out:

1086 lbs, 78.16 CG

It is a superior 0-360 with bendix FI, Hartzell CS, inverted oil, odyssey in back, no exterior paint, leather seats with painted interior. Day/night vfr with Dynon 180 and steam ASI and ALT, single comm and trans.

No intersection fairings yet, otherwise complete.

It's about the feel....

On several occasions I have had the opportunity to climb out of my -8 (180 horse counter-balanced, FP Sensi, battery in the back) and get in a friends -8 (160 horse, CS Hartzell, battery on the firewall) and fly them back to back. They feel completely different. You feel it in loops, rolls, turns, in the flare.

Mine- battery, ELT and strobe driver in the back.
His- nothing aft of the main spar.
The empty weight of the two are almost identical.

Don't get me wrong, he has one sweet -8. Just could have been a bit better.