Ragwing weight and balance

mrpibb · Post by **mrpibb** » Tue Jan 27, 2004 9:30 pm

I need to ask a question of all you ragwing owners, I just weighed my aircraft in order to get better weight and balance data. what we came up with the numbers we got that if you loaded the aircraft to its most rearward configuration we get a cg of 47" the type cert I belive is 45.2" ( this kinda concerns me ).
My empty weight cg comes in at 1340# at 39.6" , with the aircraft level my tailwheel weight is 120# (is this heavy for a ragwing?). I would like to know what other 48 owners got for numbers before I get involved in a loading schedule for my airplane.

zero.one.victor · Post by **zero.one.victor** » Wed Jan 28, 2004 1:36 am

I weighed my ragwing about a year ago. For an authoritative discourse AND the final word on all ragwing weight & balance issues,read my "Wait & Balance" article in the Q2/2003 170 News. Then send me money.

With the stock rear seat,my empty weight was 1,342, and the CG @ 38.9". With rear seat removed: 1,310 and 38.0". Single rear jump seat installed: 1,320 and 38.3". And now with venturi's/gyro's/misc removed: 1,310 and 38.44".
You're right,the TC sez rear limit is 45.2" at any weight. Be advised,the forward limit changes (moves aft) as weight is increased: at 1733# it's 36.3" but at 2200# it's 40.9" (normal category).
When mine weighed 1,342 empty,rear wheel weight (leveled for weighing) was 115#,so yours is not way off. Mine has late-model 180 gear legs,they rake forward quite a bit more than stock legs (3.5"),putting the mains farther ahead of the CG so the tail weighs more than it would with stock legs.
Like I pointed out in my article,the factory W&B sheet for my airplane sez 1,244# at 37.6". I bet it was a real hot rod at that light weight.
When you say "loaded the aircraft to it's most rearward configuration",what is the scenario? You could load it farther aft than a CG of 47" if you work at it, and still be under gross weight: for example,a fly-weight pilot,minimum fuel,and a traveling anvil salesman's sample case in the baggage compartment. (ever see the movie "the Music Man"?)
I like to go camping with the rear seat removed. I put my ice chest & other heavy stuff at the rear seat station,and throw the light but bulky stuff way in back. You might put a sign in the rear seat area "no fat chicks"--you can find one at your local Harley shop. No offense to any of the fat chicks here on the forum,of course.

Eric

Post by **Bruce Fenstermacher** » Wed Jan 28, 2004 1:52 am

Vic
I'm sure you were real careful to get the top of the door sill PERFECTLY level.
I've had the occasion to weigh my aircraft 5 times over 2 consecutive days. It was very difficult to get the same numbers mostly because of the error of my eye looking at the level bubble. This error can easily change the weight on the tail several pounds.
I actually used the average of all 5 numbers at each location for my W&B.

mrpibb · Post by **mrpibb** » Wed Jan 28, 2004 4:27 am

Eric, thanks i got to get a copy of that article. The rearward loading I was talking about is if you put two 170# (FAA) pound rear seat passengers 120# of baggage a pilot of 170# (me mabey at age 15) and meto fuel pushes the cg back to 47". I know you can move the cg more aft, it's that I as the a/c technician that weighed the airplane I have to make notice in that airplanes (mine) POH that the aft cg can be exceeded when loaded to the manufactures rearward extreme. I uploaded to my buddy's site of some pictures that I took.
Thanks
Vic
http://www.sandhillaviation.com/weight.html

N2255D · Post by **N2255D** » Wed Jan 28, 2004 8:33 am

TYPE CERTIFICATE DATA SHEET NO. A-799
Type Certificate Holder Cessna Aircraft Company
P.O. Box 7704
Wichita, Kansas 67277
==============================================
A-799 14

NOTE 2. (a) The following placards must be displayed in front of and in clear view of the pilot:

Model 170
"This airplane must be operated as a normal or utility category airplane in compliance with the Airplane Flight
Manual."

NORMAL
"No acrobatic maneuvers including spins approved.
With two people in the rear seat both front seats
must be occupied."

UTILITY
"No acrobatic maneuvers
approved except those listed
in the Airplane Flight Manual
Baggage compartment and rear seat must not be occupied."

Post by **GAHorn** » Wed Jan 28, 2004 8:14 pm

Just a helpful reminder to everyone: The loading graphs are not computed in INCHES. They are computed in "INDEX" numbers. Index is MOMENT/1000. This is a common source of confusion when loading the airplane because the loading graphs are in Index numbers.
Example: a 170 ragwing with an EW of 1340 lbs and CG of 39.6 inches would have an INDEX location on the loading graph of 53 (1340 times 39.6 = 53064 divided by 1000 = Index 53.064 to be exact.) Adding full fuel (201 lbs. and Index of 9) Plus full Oil (15 lbs, Index -.3) Plus two FAA Pilots (340 lbs, Index 12.2) will bring the airplane to a Total of 1896 lbs at Index 73.9 and dividing that Index (73900) by the wt (1896 lbs) shows the CG to be at 38.9 Inches.....well within the Utility Category. (And also notice the loading graphs do not depict the Utility Category

so you have to do the arithmetic to make sure the CG does not exceed 40.3 inches at whatever weight at/below 1900 you try to spin the thing.)

But it is possible to load individual compartments to their maximum capacity and it will put the airplane out of it's CG limits. This is what mrpibb is seeing when the airplane is not loaded in accordance with it's loading instructions. (See Note 1 of the TCDS which states, "Current weight and balance report including list of equipment included in certificated empty weight, and loading instructions when necessary, must be in each aircraft at the time of original ceritication and at all times thereafter....)
This means that in ADDITION to the 1) Airworthiness Certificate 2) Registration Certificate 3) Approved Flight Manual and the 4) Equipment list (and Radio Station License if Int'l Ops) ....there must also be ON BOARD 4) the loading instructions. (These consist of the loading graphs and the notices contained in the TCDS.)
The easy way to comply with all this is to include a copy of those graphs, your Equip. List, and your AFM ....all stuffed inside the same display envelope as your Airworthiness Cert. and Registration Cert. (Handy place in case of a ramp-check.)
And one last reminder: The Owner's Manual is NOT the Approved Flight Manual (AFM). It does contain the loading graphs, however and that is a good reason to have it on board. But the AFM is a single page document, front and back and has the stamp of approval and signature of the CAA (FAA) Inspector on it. If you don't have one, you can get one for your airplane by sending $25 to Cessna or $1 to TIC170A (members only.) Make sure you mention which model airplane you need it for.

zero.one.victor · Post by **zero.one.victor** » Thu Jan 29, 2004 1:22 am

The 1948 owner's handbook kinda sucks with regards to W&B information. All it sez is that gross weight is 2200#,and the CG range is from 36.3" to 45.2".
The W&B info on the AFM kinda sucks too. It lists CG limits as a percentage of MAC which is mean aerodynamic chord or some such gibberish. Very confusing to a simpleton like me.
The loading graph contained in the TCDS is way better than these other two sources combined. When I printed up my new W&B sheet,I included this loading graph as well as the arm of the various stations (front seat,rear seat,fuel,& baggage) along with the usual W&B information. That way,a person can look at just one document & do all the W&B calculations his little heart desires.

Eric

Larry Holtz · Post by **Larry Holtz** » Thu Jan 29, 2004 3:28 am

I bought a WizWheel from Sportys last fall. That sure takes the work out of figurin the W&B.
Larry

mrpibb · Post by **mrpibb** » Thu Jan 29, 2004 3:54 am

Well after reading the type certificate things are much clearer, I don't understand how I missed it, thanks for bringing it to my attention. Eric thanks for the email it was good reading. Sorry to jump the gun on the Cg thing itâ€™s just that getting caught up with the annual and weighing the airplane we were going thru all the paperwork and one kinda gets off track. Wasn't it Pogo that said " we have searched for the enemy, we have found them and they are us"? All I need now is some warmer weather to finish my check out and get flying.
Thanks
Vic

zero.one.victor · Post by **zero.one.victor** » Fri Jan 30, 2004 1:23 am

George,the loading graph on my copy of the TCDS,for the 1948 model anyway,has pounds on the side & CG (inches) across the bottom. No "units" or moments mentioned. The moment thing comes into play,however,when calculating W&B for your loading scenario.

Eric

Post by **GAHorn** » Fri Jan 30, 2004 2:13 am

Eric, what you are referring to in the TCDS is not a loading graph, that's a CG-Envelope graph. The loading graph is in the Owner's Manual and the loading instructions issued with the airplane Equipment LIst and it does not mention Inches....only Index Units...based on Moment.

zero.one.victor · Post by **zero.one.victor** » Fri Jan 30, 2004 7:04 am

George,the 1948 owner's manual is happily devoid of any loading graph,with index units or without. The W&B section lists the gross weight limit and CG range,and goes on to say " The actual loading of the airplane is up to the pilot.2200 lbs gross weight is not to be exceeded--and the useful load in the airplane can be distributed in any way the pilot desires,that is,in baggage (up to the baggage compartment placard limit),gasoline,or passenger weight............It is the responsibility of the pilot and operator to see that the weight and balance are within limitations."
It doesn't even list the arm for the various stations (fuel,front seat rar seat,baggae) for calculating the loaded W&B,that's only shown on the factory W&B sheet. No index units there,either,thank goodness.
Simpler is better. Them index units are worse than the "new math"!

Eric

Post by **GAHorn** » Fri Jan 30, 2004 6:26 pm

Hmmmmn. (My comments were based on the B Owner's Manual. ) I can see why that would be confusing.
Of course, for all owners, the ARM of each load is listed in the TCDS. (For the ragwing-- Front seat Arm is: 36, Rear is: 70, Baggage is: 95, Fuel is: 45 Oil is: -20)
You're right about the Index Units. Cessna really did us no favors creating that confusion.