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The Type Certificate gives this for the PA-22 150:
Normal Category:
(+17.5) to (+23.0) at 2000 lb.
(+12.0) to (+23.0) at 1800 lb.
(+9.5) to (+23.0) at 1400 lb. or less
Utility Category:
(+13.5) at 1680 lb.
(+12.0) to (+13.5) at 1665 lb.
(+9.5) to (+13.5) at 1400 lb. or less
and this for the PA-22 160
Normal Category:
(+17.5) to (+23.0) at 2000 lb.
(+12.0) to (+23.0) at 1800 lb.
(+9.5) to (+23.0) at 1400 lb. or less
Utility Category:
(+13.5) at 1680 lb.
(+12.0) to (+13.5) at 1665 lb.
(+9.5) to (+13.5) at 1400 lb. or less
Brilliant! Why didn't I think of that? Thank you!
Steve
I set this up with a moment envelope method. Keeps the math to add and subtract as the charts calculate the moment from the load. I have attached a filled example below.
Dear Tri Pacer friends, having had a look at the arms in both the XLs and pdf above, it appears that the numbers are incompatible with the arms used by my maintenance shop. They have used 59" for the avionics. Since 49" would then mean the front seats are ahead of the instruments. Any ideas?
Sounds like your avionics shop doesn't know how to calculate W&B. Go back to them and ask what they did. The Datum on the Short Wing Pipers is the wing leading edge. SOunds like they used something other than the leading edge, likely the front of the engine????
The factory W&B on my Clipper used 60” forward of the leading edge as the datum. I guess back in 49 they hadn’t discovered negative numbers and the associated math. Still using that doesn’t account for the numbers they used.
The shop may have pulled the panel location from an old equipment list without looking at current information but I am thinking the original equipment list I have for a PA20 shows 0” for the main wheel location.
The shop may have pulled the panel location from an old equipment list without looking at current information but I am thinking the original equipment list I have for a PA20 shows 0” for the main wheel location.
I believe the main wheel axle Center line is the same station as the wing leading edge. TCDS calls the leading edge as the datum. AS Gilbert stated, he has W&B info from the factory that used something like 60" in front of the leading edge as the datum. About the only thing to do is work back through all the old W&B calculations and correct for a standard datum.
Here you go. Its a scan of the Clipper original cardboard Airplane Flight Manual dated October 18, 1948 Subtract 60 from each of the arms to get the real arm from the leading edge of the wing which you will notice is 60"
A lot of the early Pipers used 2 reference points for weight and balance. The factory original W&B / equipment list for the PA20 I had showed 60” forward of the WLE as the datum then computed W&B and equipment locations from the WLE. As a result, some subsequent W&B computations were incorrectly accomplished. I believe it to be a common problem on many Shortwings.
I don’t have my drawing cd handy to see where the panel would be located in relation to the WLE on PA22. I think he should be armed with before confronting the avionics shop.