Weight and balance questions

farmerbrake

farmerbrake

Line Up and Wait
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farmerbrake
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Attached is a picture of the loading graph to figure out the moment of our arrow.
My question is: where the diagonal lines stop, is that the maximum amount of weight allowed in that particular area? Or can you extended those lines provided
a) it's not specifically prohibited (like in the baggage area)
b) the cg & gross weight are all within specs
Thanks in advance!
 
Unless there is a limitation somewhere, you can extend those. Cessnas just give you the station instead of graphing a line. That's equivalent to the slope of the line.

Obviously, you can't extend the fuel line, as the capacity of the tanks is less than 300 lb.
 
Maybe a little clarification is in order...

For performance tables, extending lines is a really bad idea, because there is no guarantee the lines are straight. Absent test data, you don't know. Generally drag and friction get worse the faster you go, well out of proportion, so extending the lines as straight will overpredict performance. Not a good thing.

For weight and balance, moment is EXACTLY equal to weight*station, all the time, no matter what. That means you do know the line is always absolutely straight.
 
Thanks for the responses everyone. The line in question is the rear passenger. It stops at 340, my 2 people would be 350.
Granted I need to run all the other numbers to confirm I'm still in CG, but I wanted to double check my thoughts before doing too much math
I don't have foreflight to do my W&b for me. Any other app suggestions for that?
 
Jesse has an app for that here but I like a calculator and the W&B data in the manual. Weight times arm equals Moment. Add the weights and moments then divide the total moment by the total weight.
 
farmerbrake said:
Thanks for the responses everyone. The line in question is the rear passenger. It stops at 340, my 2 people would be 350.
Granted I need to run all the other numbers to confirm I'm still in CG, but I wanted to double check my thoughts before doing too much math
I don't have foreflight to do my W&b for me. Any other app suggestions for that?
Click to expand...

That page was printed May 14, 1973. The good old days before Whopper burgers and Supersized Cokes and fries. When a pair of adults could easily top out at less than 340 pounds.
 
Dan Thomas said:
That page was printed May 14, 1973. The good old days before Whopper burgers and Supersized Cokes and fries. When a pair of adults could easily top out at less than 340 pounds.
Click to expand...
If you average out all 4 people going to be in the plane it's 175.
I wouldn't have asked this if I (the pilot, and also the smallest person) could sit in the back lol.
 
Usually it works out best if you can have more weight in the back than the front. The most efficient place to operate is at the aft CG limit.
 
Sac Arrow said:
Usually it works out best if you can have more weight in the back than the front. The most efficient place to operate is at the aft CG limit.
Click to expand...
Most efficient for cruise, but you lose some control authority. No big deal if you are loading up and flying cross country in a nosewheel, but not always the best in some applications.
 
Never been a fan of that style of W&B, always prefer the dot in the envelope range, if you're going to be flying the plane much, I'd make a W&B profile in foreflight for it, fltplan also has a free W&B and I'm sure they have an arrow template.

image.png
 
Fearless Tower said:
Most efficient for cruise, but you lose some control authority. No big deal if you are loading up and flying cross country in a nosewheel, but not always the best in some applications.
Click to expand...

More accurately you lose some longitudinal stability. In the Arrow specifically, particularly the Turbo Arrow, landings are a lot nicer with a rearward CG. It's difficult to properly flare with the CG too far forward.
 
farmerbrake said:
Thanks for the responses everyone. The line in question is the rear passenger. It stops at 340, my 2 people would be 350.
Granted I need to run all the other numbers to confirm I'm still in CG, but I wanted to double check my thoughts before doing too much math
I don't have foreflight to do my W&b for me. Any other app suggestions for that?
Click to expand...
Paper and pencil? ;)
 
paper and pencil? I dont think so.
 
As an update to this it worked out just fine. Had an awesome flight (even if it wasn't the one I originally planned). Thanks for all the help!
 
James331 said:
Never been a fan of that style of W&B, always prefer the dot in the envelope range, if you're going to be flying the plane much, I'd make a W&B profile in foreflight for it, fltplan also has a free W&B and I'm sure they have an arrow template.

image.png
Click to expand...

I have an app called simply "aviation W&B" (for iPad, not sure if they have it for android or not) that is excellent. Still I am a student and I use this type, as well as printout of the actual one, calculate...so far it's been right on the money.
 
farmerbrake said:
Thanks for the responses everyone. The line in question is the rear passenger. It stops at 340, my 2 people would be 350.
Granted I need to run all the other numbers to confirm I'm still in CG, but I wanted to double check my thoughts before doing too much math
I don't have foreflight to do my W&b for me. Any other app suggestions for that?
Click to expand...

10 lbs over. 2 people. 5 lbs apiece. Tell them no breakfast and get naked before getting in.
 
There has to some kind of limit to extending that line out to where ever you like. Where the limit is, I don't know, but at some point there's always a structural limit.
The structural limits are the seat and attach structure and the floor itself for weight alone, and the seats, belts and shoulder harness attachments in case of an accident.
 
The TCDS has the information that you seek. There is a limit to weight at certian stations, specifically the baggage area.
 
bluerooster said:
Heaven forbid they ever have to work out a wind triangle with paper and pencil. :eek:
Click to expand...

Yeah, I'll just play around till my CDI settles down and call it a day, or hit the AP/GPSS button ;)
 
I guess one way to look at the truncated lines is that in an older plane they may, in and of themselves, delineate a limitation. I'm talking about before POH's got standardized and formally listed them in Section 2.

You have to ask yourself: why else would they stop a line at a certain weight?
 
I was always told never attempt to interpolate at the end of the lines.
 
FastEddieB said:
I guess one way to look at the truncated lines is that in an older plane they may, in and of themselves, delineate a limitation. I'm talking about before POH's got standardized and formally listed them in Section 2.

You have to ask yourself: why else would they stop a line at a certain weight?
Click to expand...
Because they didn't expect people to need a longer line.

The Warrior POH certainly lists limitations, but it still assumes you'll never put more than 350 lb in the back seat. It's essentially a 3 person aircraft, so you can see where such an assumption might come from. A single 350 lb person would have trouble getting through the door to the back seat.

The answer is quite different from performance numbers.
 
Capt. Geoffrey Thorpe said:
Good Lord Man!!!! We are talking about algebra here! You can't expect a pilot to understand 5th grade algebra, can you? Aren't you aware of the current state of our education system?
Click to expand...

Here I am reading along feeling smug and then BOOM! I didn't get to Algebra until 8th grade. I'm so backwards...
 
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