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Weight & Balance

Posted: Tue Dec 23, 2008 12:37 am
by 170C
George, this might need to be in the "rear seat removal" thread, but maybe not and if not I don't want to add to the already lengthy thread. The discussions about the rear seat removal got me to thinking that at the very least I had better do some w&b calculations for my ole bird and have them in the plane since I often do not have my "single" rear seat installed, but do so at other times and who knows, I might want to remove all of the seats like the photo in the manual with only the pilot's seat remaining or other possible configurations. I was looking at my friends C-206 data and in his manual it shows dimensions and/or stations for each of the 6 seats. Looking at my owners manual for the '56 C-172, I see that there is a page showing cabin dimensions, but no data on distances from the firewall or station dimensions (hope I am using the correct wording). That page in the C-172 owners manual is identical to page 21 in the '56 C-170B owners manual. Is there a source for these measurements for our planes? Unfortunately it has been so many yrs since I did a w&b calculation I am really rusty. Kind of like figuring the wind triangle on the old E6B :?

Re: Weight & Balance

Posted: Tue Dec 23, 2008 12:56 am
by GAHorn
Yes, Frank! Look at the TCDS, and you will see the number of seats, their weights, and their moment/arm listed in the first section of the sheet.

Re: Weight & Balance

Posted: Tue Dec 23, 2008 2:50 am
by Brad Brady
gahorn wrote:Yes, Frank! Look at the TCDS, and you will see the number of seats, their weights, and their moment/arm listed in the first section of the sheet.
Ata Boy, George.......your going to get people looking at the TC's yet for reason for change,or not.... just as they were originally written.....To change you better have a really good reason...(usually a 337 works) :wink:

Re: Weight & Balance

Posted: Tue Dec 23, 2008 3:20 am
by Bruce Fenstermacher
Frank I'm sure I attached these files before but will post them again because I could not find them. They are W&B spreadsheets done in Excel that I created some time ago for all the models of our aircraft. I believe you will find the A orB model to be the one you would use. There are other sheets and web based calculators as well. These will make you job easier. Just input empty weight data from your aircraft. Change the loading to anything you desire. Print the result.

Excel calculators are now found here: [http://www.cessna170.org/forums/viewtop ... 379#p93278

Re: Weight & Balance

Posted: Tue Dec 23, 2008 5:45 pm
by jon s blocker
Bruce,
In looking at your W&B w/ Javelin fuel tank, I see you put in there, (15 gal max). I believe my Jav. tank holds 18 gals. Is there some reason for the 15 gal max? Just curious. Am I missing something? Thank you. Jon

Re: Weight & Balance

Posted: Tue Dec 23, 2008 7:35 pm
by Bruce Fenstermacher
Jon it's been a while since I did that so I don't remember were I got the data. But after review of the TCDS it is clear to me that the 15 is a typo. There isn't really any built in restriction so you could put 18 gallons in the window of the old version.

HOW EVER

After rereading the TCDS I realized I had not accounted for the 3 lb unusable fuel and then subsequently found the calculations to add the Javelin tank to the rest of the sheet were wrong resulting in no weight being added. Not sure how many people have tried to use the Javelin tank version but no one has noticed before. :oops: :oops:

I've fixed the version listed above to account for the unusable fuel associated with the Javelin tank as well as corrected the calculations so they actually work. Thanks for pointing this out John.

Re: Weight & Balance

Posted: Tue Dec 23, 2008 7:47 pm
by GAHorn
did you actually mean to say 3 pounds? or 3 gallons.

Re: Weight & Balance

Posted: Tue Dec 23, 2008 7:52 pm
by Bruce Fenstermacher
It is 3 lbs for the Javelin tank according to note 1 at the bottom of the TCDS.

Re: Weight & Balance

Posted: Fri Dec 26, 2008 2:32 pm
by jon s blocker
By the way Bruce, I wanted to thank you for taking the time to publish your W&B packages for the rest of us. I know it takes alot of time and effort to put these things together. Your efforts are highly appreciated. Jon