Jump to content
Sign in to follow this  
Animosity2k

Weight & Balance Help w/ Foreflight Help Needed

Recommended Posts

Hello everyone. I am working on some weight and balance problems on an exam from my flight school and am stuck. I chose to use my iPad to answer them in combination with the POH. I've attached the question and what I came up with in my Foreflight W&B section. I have two "notices" popping up that I am unsure of how to address them.

1) Each forward CG limit point should have a unique weight
2) Each aft CG limit should have a unique weight
3) For fuel do I select ignore ARM and use moment table or do I use arm? And according to the photo I took from the POH I am using an empty fuel tank ARM even though my tanks are full? 

Thanks everyone.

image1 (8).jpeg

image1 (7).jpeg

image1 (6).jpeg

image2 (2).jpeg

Share this post


Link to post
Share on other sites

Setting up  Foreflight might be more work than it's worth, for now. As for the fuel, the weight times the arm are the two pieces of the moment. If the weight is zero, there is no moment to add in. Of course there will be and its moment (lbs x arm) will add to the others. In the end you divide the total moment by the total weight ( less than 1320 lbs) and get the CG. Then look the CG up on the chart envelope to see if all is OK.

The other moments are pilot and passenger (each weight x 20.5 in of arm), and baggage (weight x 45 in of arm). Don't forget the empty weight of the plane times its arm from off the plane's data sheet (mine is 13.7 in).  Cheers !

Share this post


Link to post
Share on other sites

I use garmin pilot and just made my own spreadsheet in Google sheets.  I can plug in each passenger weight, gallons of gas and baggage and it spits out not only the total weight and CG but also my stall speeds at level, 30°, 45°, 60° along with each flap setting.

I'm a little OCD though 

Share this post


Link to post
Share on other sites
On 7/27/2019 at 8:38 PM, okent said:

I use garmin pilot and just made my own spreadsheet in Google sheets.  I can plug in each passenger weight, gallons of gas and baggage and it spits out not only the total weight and CG but also my stall speeds at level, 30°, 45°, 60° along with each flap setting.

I'm a little OCD though 

Can you share said spreadsheet?

Share this post


Link to post
Share on other sites

Don't know if this will help, but this is how I have my weight and balance profile setup on foreflight.  This is for a CTLS.  You will need to change the empty weight and moment/cg on the setup page, and probably the cg arms for the seats and storage compartments.  This comes extremely close to what I get doing it by hand.  Let me know if you need any help setting it up.  If you can get me the empty weight details, I can make you a profile and send it.

 

IMG_5181.thumb.PNG.fc5ead56a0d31d37359acb6d24f86592.PNGIMG_5182.thumb.PNG.d27c5fc95b6bc527a1e38731494ca6a1.PNGIMG_5183.thumb.PNG.6912454f9f7439b790cd127c48968cd9.PNG

Share this post


Link to post
Share on other sites

I use google sheets and this file is a conversion to Excel.  All you do is plug in the values into the grid on the right side for pilot/passenger etc and it populates the left side with everything including Vs by weight based on bank angle.    Just change out your weight/arm/moment numbers to match your airplane.

The Margin number below the max value for weight will change from green to red if overweight.

The Total Arm number will change from green to red if you are out of CG.(this assumes that everyone has the same range.  If not then you will have to adjust the conditional formatting of the color change ranges)

The two grids at the bottom show Vs values: one at max weight and below that are theoretical numbers as to what the stall speed should be based on your actual weight. This is an extrapolation of the max weight POH numbers based on the formulas to calculate stall speed based on the wing load at a given angle.  I rounded up to the nearest whole number so there is no way a rounding error could spit out an incorrect low number.

There was no listed stall speed for flaps at 15 degrees so I split the difference between 0 and 30 and rounded up to the nearest whole number.

Any feedback is appreciated, especially if anyone has checked what their stall speed is at a given weight and if it differs from the POH number at gross weight.  The numbers really don't change much unless you are really light or grossly overloaded or over 30 degrees of bank.

I am going to make one for takeoff and landing distance based on weight and density altitude as well.

Tom

W&B NXXXX.xlsx

Share this post


Link to post
Share on other sites
On 7/31/2019 at 7:00 PM, garrettgee2001 said:

Don't know if this will help, but this is how I have my weight and balance profile setup on foreflight.  This is for a CTLS.  You will need to change the empty weight and moment/cg on the setup page, and probably the cg arms for the seats and storage compartments.  This comes extremely close to what I get doing it by hand.  Let me know if you need any help setting it up.  If you can get me the empty weight details, I can make you a profile and send it.

 

IMG_5181.thumb.PNG.fc5ead56a0d31d37359acb6d24f86592.PNGIMG_5182.thumb.PNG.d27c5fc95b6bc527a1e38731494ca6a1.PNGIMG_5183.thumb.PNG.6912454f9f7439b790cd127c48968cd9.PNG

Garret, good-day sir, do your fore and aft CG limits come from a particular POH? My numbers are 11.8 and 17.3  from my poh.

Share this post


Link to post
Share on other sites
5 hours ago, AirHound said:

Garret, good-day sir, do your fore and aft CG limits come from a particular POH? My numbers are 11.8 and 17.3  from my poh.

This is from my CTLS AOI. I have attached a picture and highlighted the limits I used for this setup. This one comes from FD USA, but mine matches it.

Hope this answers your question.

790CC430-6ACC-4A2B-A7EA-67142D4B886B.jpeg

Share this post


Link to post
Share on other sites

I’m guessing the difference in numbers is the dif between a 912 and an 912is and each aircraft’s unique equipage. Mines a 13 is model, but I just have POH’s not a an AOI. I’m second owner.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...