W&B problem

[N74DV]

help me out here

my plane has 12 gallons in it right now (72lb at -9"). The IA put leveled the tail and put it on the scales.

The mains (measured at +2" from datum) are 833lb

Tailwheel (measured at 200" from datum) is 67lb


can someone tell me what the empty W&B would be without fuel. The IA and I are coming up with different numbers. If he is correct then my plane is VERY tail heavy

[Mark Julicher]

Re: W&B problem

DJ,

The empty C.G. is 14.8 to 17.9 for a BC12-D
The flight C.G. is 24.2 to 20.0

This is all in the type certificate data sheet.

[N74DV]

Re: W&B problem

Yes I know that information. My request is for someone to do the arithmetic on my particular case.

My IA comes up with 19" empty which is beyond the limit

I get 16.5" which is within limit.

I'm wondering if either of us is correct.

[Mark Julicher]

Re: W&B problem

Well,
If you remove weight from ahead of the CG then the CG moves aft.
I calculate your empty CG to be at 18 inches, but I need t go check my math.
Your empty plane is 828 lbs ...

[Mark Julicher]

Re: W&B problem

DJ,

I just checked my plane's numbers. My plane weighs 827 empty which is only one pound less than yours.

My tail wheel weight is 68 lbs.

my numbers:

mains 759 lbs at 2 inches
tail 68 lbs at 193 inches
empty CG is 17.7

Sounds like yo got the tail arm length off by 7 inches

[Guest]

Re: W&B problem

this is from a spread sheet, EWCG in red

it looses the format here but you can figure it out

length to tail wheel center (ie where the weight bears down, so to the center of the wheel) MUST be measured for your a/c

maybe you forgot to take out the oil, CAR required it (subtracting the oil) but not FAR23, yours is a CAR certified plane

desc wt arm moment
LH Main scale 416.5 2 833
RH Main scale 416.5 2 833
Tail wheel scale 67 200 13400
total scale weight 900 16.7 15066

fuel -72 -9 648
oil -7.5 -21 157.5
empty weight 820.5 19.3 15871.5

[Mark Julicher]

Re: W&B problem

DJ,
The type certificate data sheet says the tail wheel arm is 193 inches

[Mark Julicher]

Re: W&B problem

DJ,
Unless you have a non-standard tail wheel arrangement your tail moment arm is incorrect!!
Your plane is fine.

[Guest]

Re: W&B problem

see page 86 of this for info about CAR planes (what an irony) not having oil as part of the empty weight

http://www.faa.gov/library/manuals/aircraft/media/FAA-H-8083-1A.pdf

[N74DV]

Re: W&B problem

using a plumb bob to mark a line on the floor at the datum, my tail wheel axle is 200" aft.

see page 86 of this for info about CAR planes (what an irony) not having oil as part of the empty weight

which would make my plane even tail heavier at empty weight.

I just can't believe that my plane is nearly 2" aft CG when empty. My god what's next with this thing!

[Guest]

Re: W&B problem

using a plumb bob to mark a line on the floor at the datum, my tail wheel axle is 200" aft.

sounds correct to me, I think mine was 198

will be diff based on spring and wheel combo

the 193 in tcds is most likely to the tailwheel cg not the axle

[Guest]

Re: W&B problem

using a plumb bob to mark a line on the floor at the datum, my tail wheel axle is 200" aft.



which would make my plane even tail heavier at empty weight.

I just can't believe that my plane is nearly 2" aft CG when empty. My god what's next with this thing!

mine is similar, I think they all are actually,

make a loading schedule and worry no more

I have a spread sheet I could send you to help make the loading schedule

[N74DV]

Re: W&B problem

well my IA won't sign off anything if the numbers don't match the TCDS. So somehow I need to figure a way to shave about 20lb from the tail or add 60 to the front.

I'm slowly becoming a nervous wreck because of this aircraft.

[Guest]

Re: W&B problem

well my IA won't sign off anything if the numbers don't match the TCDS. So somehow I need to figure a way to shave about 20lb from the tail or add 60 to the front.

I'm slowly becoming a nervous wreck because of this aircraft.

That's not right.

Read

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99C827DB9BAAC81B86256B4500596C4E?OpenDocument

Chapter 10

All you need to do is make a loading schedule, it is not required that the ewcg be in that range

it only has to be there to avoid doing a loading schedule

[Mark Julicher]

Re: W&B problem

Just Damn!

The TCDS says the tail wheel is at 193 inches. If you follow that you are OK. Otherwise I guess you are not.