Weight and Balance

[47snoopy]

I have a Sidewinder that was built as a taildragger. The previous owner changed props but did not do a W & B. Anybody who could give me some hints on how to set up a taildragger properly using the RAA scales? The scales are definitely inexpensive to rent, the deposit of 1500 bucks seems a bit excessive though. Not that long ago, the deposit was in the low three digit numbers.

[Snowflake]

Might be a little late to reply to this, but maybe it will help someone else in the future... I helped a few people weigh taildraggers with the RAA scales, and this is what seems to work best:

1. Weigh the aircraft in three-point attitude.  Add together the weight on all three wheels.
2. Raise tail to flying attitude, and weigh the mains.  Add these together.
3. Subtract the total (2) from the total (1).  The result is the weight on the tail in flying attitude.

You now have the weights necessary to calculate your C-of-G.  All you need is your distances from the datums.  For a "known" design like an RV, you can pretty much take them from the plans.  If you have something else, you'll need to measure them.

This has the benefit of not requiring you to build a support that will hold the tail up and/or the scale up at the same time.  You just roll the plane on the scales, note the numbers, then have a stout friend lift the tail, record some more numbers, and you're done.  An RV can be weighed in about 10 minutes using this technique.

FYI - Nosewheel aircraft can be weighed using a similar procedure... Weigh all three gear, then pull the scale from under the nosewheel and lower it until you're in flying attitude.  If you're lucky, you won't need a hole in the floor for the nosewheel to sink into...

[toucan]

Hi,

I did my first W & B on my Toucan last spring. It was a bit of a Red-Green show, three newbies, but at the end of the day it gave me data to work on.
Our scales would not pass TC, but at the end of the day any information is better than a shot in the dark. Perhaps at a later date we can borrow the scales they use on the Dehavilland Beaver...
I now have a datum, etc.
Bill Spring, who is/was a member here helped me formulate a MAC, the Toucan wing is not a constant Hershey-bar chord, some similarities to the Lazair (because Corley and Kramer worked and flew together).
I really want to nail down the aft C of G. I am confident in her, BTW I want to be absolute. (I have reports she  has hauled a lot of weight behaind the PIC.)

drh
CYEL

[aviator3230]

Chapter 85 members just did a Weight and Balance on Peter Whittaker's Zenith this morning (June 09/12) using the RAA scales. It was pretty simple, and in a half hour we were done. A great project visit as well! Peter's 601 HDS is scratch-built and a real pretty airplane.

We hope to have an article on weight and balance in an upcoming issue of the Recreational Flyer.