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Empty Weight

J

JohnF

Well Known Member
Electronics scales...empty weight came in at 728-lbs. Good. CG in range OK.
DAR Friday.
 
No extras, no paint...will fly it that way for a while...up to a year maybe, then paint as inspiration dictates.
 
Final Weight

Mine was 742lbs with a CG of 81.8. With every option except wheel pans. No paint for now.

John
RV12 Flying 6/5/2010
N1212K
 
Mine...

741 pounds with CG @ 80.7, all options except wheel pants, and no paint, yet. Wheel pants will add 10 pounds, and paint ??

Tony
 
Ooops ! I said I had 728-lbs empty weight with NO options...I lied...I have the autopilot/servos installed...forgot they were options.
 
Well, as long as we are coming clean...my weight of 741 lbs also includes about 30 cans of NAPA 7220 rattle can primer used on internal structures and 10 cans of interior paint;).

Tony
 
Tony_T said:
741 pounds with CG @ 80.7, all options except wheel pants, and no paint, yet. Wheel pants will add 10 pounds, and paint ??

Tony
Click to expand...

Jetguy said:
Mine was 742lbs with a CG of 81.8. With every option except wheel pans. No paint for now.

John
RV12 Flying 6/5/2010
N1212K
Click to expand...

Just a general observation....
both of these RV-12s' weight pretty much exactly what I would expect them to weight with the options that are installed.
The problem I see is that stated empty C.G. positions are almost 1 inch different.
I don't know which, but my guess is that at least one of you is wrong. This could be caused by a number of factors. The first two that come to mind are that the airplane wasn't exactly level when weighed, and/or the canopy was open (though I don't think this by it self could cause a 1 inch shift in C.G.
 
Hmmm...looking at the sample loading problem in the POH, the aircraft weight is 738 lbs and the arm is 81.93. So mine is the one that looks suspicious.
I will empty the fuel tank and redo my weight and balance.

Tony
 
CG Chart

Tony if you run some example Loads you will see that you are right on the Front edge of the CG envolope.
Example: WT 741 Moment 59798.7 CG 80.7
2 pilots 430 Moment 33905.5
fuel 30 3308.4
Total 1201 97012.6

Somebody check my math but I think this is correct. Big pilots I know! Im 6'2" 215lbs. What do you guys think?
This is based on page 4-4 in the POH.
John

WBChart009.jpg
 
I was concerned when my arm came out much different than the sample. I e-mailed Scott at Vans, and had him look at my numbers. He sent me the actual numbers of their RV-12. Their weight is 730, with an arm of 81.69. He suggested that my weight on the nose wheel looked heavy. Playing around on Excel, I found that even a small change on the weight of the nose wheel made a huge difference. I also received 6 W&B's from other builders. The distance from the leading edge of the wing to the nose wheel axle also varied from builder to builder. Mine was 40.125, another was 40.375, one was 40.5, 3 were 41, and the last was 40.75 Vans was 39.82. These too make a difference. A slight variation on the nose wheel distance plus a little on the nose wheel weight makes a 1" difference. I'm guessing that the above 2 W&B's really are not one inch apart. I'm also not sure that it makes much difference. With my numbers I tried to come up with real world loading scenarios and coudln't get outside the envelope.
 
Mark Henderson said:
I was concerned when my arm came out much different than the sample. I e-mailed Scott at Vans, and had him look at my numbers. He sent me the actual numbers of their RV-12. Their weight is 730, with an arm of 81.69. He suggested that my weight on the nose wheel looked heavy. Playing around on Excel, I found that even a small change on the weight of the nose wheel made a huge difference. I also received 6 W&B's from other builders. The distance from the leading edge of the wing to the nose wheel axle also varied from builder to builder. Mine was 40.125, another was 40.375, one was 40.5, 3 were 41, and the last was 40.75 Vans was 39.82. These too make a difference. A slight variation on the nose wheel distance plus a little on the nose wheel weight makes a 1" difference. I'm guessing that the above 2 W&B's really are not one inch apart. I'm also not sure that it makes much difference. With my numbers I tried to come up with real world loading scenarios and coudln't get outside the envelope.
Click to expand...

The actual position of any of the wheels shouldn't make any difference in the result of the measured C.G. position (other than the small effect caused by the weight of the wheel being in a slightly different position.

Having a correct empty C.G. position is very important. If it off by one inch, when you refence the chart and determin taht you are with 1/2 inch of teh C.G. limit you could in reality by 1/2 inch beyond it.

The above weight for the RV-12 prototype (highlighted red) was with only the autopilot option.
 
Just for comparison my empty CG is 82.3. The airplane is equipped with the autopilot option, and is painted. I have run numerous scenarios on w&b and while I can get close (84.9) to permissable aft cg (85.39) with my wgt (175) and full tank all are w/i the envelope. Any thoughts on these numbers?
Thanks
Dick Seiders
 
Oops! Need to mention that when on full tank at start. and alone I can have no baggage over 15lbs. unless it is on the passenger seat.
Dick Seiders
 
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