WnB Pro

loudbagel

loudbagel

Pre-takeoff checklist
Joined
Jan 16, 2011
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Hummingbird Saltalamacchia
So I need a little bit of help setting up WnB pro for my plane.

1. I entered the following stations in, using mom/wt to determine arm
  • Empty Aircraft- 47.84
  • Captain - 36
  • Copilot 36
  • Rear Pax 70
  • Baggage- 95
  • Fuel 48
  • Oil - -.2

Then copied the following envelope points in using the POH graph
  • 54/1500
  • 68/1850
  • 88/2200
  • 103/2200
  • 69/1500

Then slid my weight into the captain spot (165lbs) full fuel (39 gal) plus 20 pounds of baggage, this is clearly within the weight and balance limitations for the 172 however this app does not recognize that and wont even show me near the correct wt and mom ??

Any ideas on how to figure this out would be appreciated!
 
Touch Actions, then Share Airplane, and paste the share code.

There is not enough information available in what you posted above for me to help you. You didn't provide the empty weight.

Have you actually tried to do a weight and balance calculation by hand given the information you're giving the program? I'd bet that if you do you'll come up with the same result as the software. It's pretty basic math and if bad data is given a bad result is what you get.
 
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I haven't had any issues with it. But I always start with a template, it is easier to adjust than it is to start from scratch.
 
DavidWhite said:
What year 172 is it?
Click to expand...

Its a 1961 172B.

Have you actually tried to do a weight and balance calculation by hand given the information you're giving the program? I'd bet that if you do you'll come up with the same result as the software. It's pretty basic math and if bad data is given a bad result is what you get.
Click to expand...

Yes, went and did it the old fashioned way twice, both times yielding correct wnb .
 
Can you share the airplane as I asked above and paste the share code in? It's pretty much impossible for me to help you without that as you didn't provide all the data above.
 
jesse said:
Can you share the airplane as I asked above and paste the share code in? It's pretty much impossible for me to help you without that as you didn't provide all the data above.
Click to expand...

Try

4HH
 
Just by once glance at the envelope image I can tell you the problem....
q5Oz4.jpg


You're inputting an envelope that isn't based on arm/cg. I'm guessing you're pulling it out of the POH and if you look at the units you'll be seeing moment and weight. Not Arm and weight. Moment and arm are not the same thing so you need to convert moment to arm. Moment = Arm * weight.

If you do the math of the data you're inputting as I suggested above you'll end up with the same answer as the software:
Empty Aircraft: 1362.5lb * 47.84" = 65,182 lbs/moment
Captain: 164lb * 36" = 5,904 lbs/moment
Baggage: 19lb * 19" = 1,805 lbs/moment
Fuel: 39 gallons * 6.02 lbs per gallon = 234.78 lbs * 48 = 11,269.44 lbs/moment

Sum of all the weights: 1780.28 (rounded down to 1780 for display purposes)
Sum of all the moments: 84,160
CG: 47.27" (rounded up to 47.3 for display purposes)

So as we can tell the software produces the same answer as calculating this by hand using the data you gave it would. So that eliminates the possibility that the software is doing this wrong.

So now the question is -- what is wrong with the data?
- Your envelope points are wrong. You inputted units of moment as if they were arm without converting them to arm
- You only put in a normal category when the airplane has both a normal and certified category.

I fixed the above and created a new profile which outputs the following with your data:

goy6I.jpg


bZYLa.jpg



You can see you're outside the envelope still..Since I verified:
-The station arms are correct via the TCDS
-The envelope is now correct via the TCDS

This leaves only one thing thing:
Either your empty CG or empty weight are *WRONG*. Or your airplane has something very strange about it and isn't in balance with that load. Where did you get those from?

Something just doesn't add up with this..and as the PIC you should be able to figure out what it is pretty quickly. It's not my software. It's the data being inputed. If that is the real CG you're using for your weight and balance calculations on paper then you'd be outside the envelope. If you're not outside the envelope you're doing it wrong.

I'd suggest you confirm your empty weight and CG. Perhaps some 172B expert here can tell us what a more realistic empty weight/arm should be for this model.

You can retrieve the profile I configured based on yours with the envelopes corrected by loading share code:
4HJ

I'm highly suspect of your empty weight/CG.
 
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The CG can't be 48 on an Empty C172, can it? Well, as Jesse said, at least not with an envelope that looks like that...

The software has a C172 template, start with that and just adjust everything to match. Your Env in your POH is probably based on Moment, so just convert it to Arm and you will be all set. YOu may have to do the same for some of your stations, depending on how it is provided to you..
 
The 1959 C172 (not A model) had all weight charts showing Moment's only. Gross was 2200 lbs and empty weight was around 1350 with 36.8 Arm
 
I'll be in touch with the owner this afternoon to verify the numbers
 
Just look at the numbers. You should be able to determine if they are units of arm or units of moment. If they are moment/1000 then multiply it by 1,000 and divide by weight and you've got arm.
 
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