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W&B Calculations

CharlieWaffles

CharlieWaffles

Well Known Member
Does anyone have their copy of their W/B calculations they used for airworthiness? The Vans manual has several examples, but none of them match the actual template they then provide. I'm unclear which scenarios should have passengers included, what the definition of a "minimum pilot weight" and "heavy pilot weight" would be, as the I know the standard is 140. Also, should the weights and calculations be made so that the resulting CG is IN the envelope? Such as ensuring there is baggage so that a standard pilot and min fuel calculations show as in envelope, or do I leave baggage out and show that the calculation is outside the envelope?
 
Basically there are 4 scenarios the inspector will want to see.
1/ Empty weight
2/ Gross weight; all seats full, full fuel, and baggage up to gross weight
3/ Most forward CG; aircraft loaded to the maximum forward CG limits
4/ Most aft CG; aircraft loaded to the max aft CG limits
 
BobTurner said:
You can buy a certification paperwork package from EAA for about $30. Well worth it imho.
Click to expand...

I have this, but to do the W/B scenarios there are still some assumptions that aren't clear. I called Vans and even they weren't 100%, so I made the scenarios "work" but changing values until it was in the envelope. Essentially, what does it take to be in the envelope type calculations.
 
Brian,

That's the lowest empty weight I've seen for a -10. What's your secret?
(No paint, no oil, no fairings, no interior, filled with helium?).

Bob
 
RV-10 weight & balance

JCleary_Weight_and_Balance spreadsheet

Here is a spreadsheet I used and it worked great
 
BobTurner said:
Brian,

That's the lowest empty weight I've seen for a -10. What's your secret?
(No paint, no oil, no fairings, no interior, filled with helium?).

Bob
Click to expand...

Mine was 1526 before paint and 10 qts of oil. Now 1556. Cloth seat covers, painted interior, 925/680 batteries in the back, ifr panel and 1/8" fiberfrax on fw/tunnel bottom. If you have a normal size family of four and you want to haul any baggage with full tanks you had better be under my weight.
 
BobTurner said:
Brian,

That's the lowest empty weight I've seen for a -10. What's your secret?
(No paint, no oil, no fairings, no interior, filled with helium?).

Bob
Click to expand...

That is no paint and no interior - pretty minimal everything else. Its going to end up closer to the high 1500's when its all said and done :)
 
Error Analysis

It has always bothered me how some pilots use an average arm for the pilot, copilot, and baggage, and then run the cg right to the edge.
(My spread sheet lets me put in the actual arms for front seats, bags).

I did a little error analysis for my plane, in typical aft and forward loadings. Here are the results.

I arbitrarily looked at what it would take to move the cg by 0.11"

Aft case (front seats 340 lb, pass seats 250 lb, 150 lb bags, full gas)
When weighed plane, main gear off by 3%
When weighed plane, nose gear off by 1.2%
(these two tend to cancel, so if it was the scale that was off it would need to be off by 2%)
When weighed plane, main gear arm off by 0.25", OR nose arm off by 0.75"
Pilot and copilot position off from average by 1"
Pilot and copilot weight off by 200 lbs (!)
Passenger weight off by 9 lbs (!!) (Do your passengers tell the truth?)
Bag weight off by 5 lbs (Do you weigh your bags?)
Bag location off from average by 2"
Gas off by 7 gal (this is why you need to check take off and landing cg).

Forward case (one 170 lb pilot, 25 lb bag, full gas)
When weighed plane, main gear off by 1.3%
When weighed plane, nose gear off by 1.1%
(these two tend to cancel, so if it was the scale that was off it would need to be off by 9%)
When weighed plane, main gear arm off by 0.2", OR nose arm off by 0.6"
Pilot weight off by 40 lbs
pilot position off from average by 1.4"
bag weight off by 3.5 lbs
bag location off by 10"
fuel off by a bit more than 60 gal
 
I used average arms and loaded to gross and aft limit during phase 1. I routinely fly with my family at our aft limit. It handles much differently than at the fwd limit. There are safety margins in Van's numbers so that if our 100 lbs of baggage is slightly more aft than centered on the average baggage arm we won't fall from the sky. I do weigh baggage going on big trips, but do not worry if it is perfectly centered.
 
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