REFLECTOR: Weight and Balance Levelling

Tue Nov 11 06:54:14 CST 2008

Dear all,
Here below was a piece I posted when I did my wgt and balance.  I hope it
helps.  I am happy to talk further on this if somebody needs further ideas.
I used Ronnie Brown's program.  
Terry

Dear All,
I did my wgt and balance this week.  Here is the news and comments.  

First the news:  She came in at 1892.5 pounds and 136.7 aft of datum. I am
very happy with that.  Here are some particulars:
	300 HP Lycoming which is another 60 pounds more than the 260 HP
version.  
	Two full sized batteries in the nose, 
	All the seats, seat cushions, hooker seat belts, and the false fire
wall in place.  No carpet or headliner or trim. 
	A couple of headsets, and my backup handheld GPS and VHF/VOR ICOM
and a small fire extinguisher.  
	A final exterior paint job and some Zolatone on the gear legs, wheel
wells and ceiling beams    

I used locally borrowed certified scales.

Minor irregularity:  I thought the "Owners Flight Manual and Wgt & Bal" book
was nicely done and provided me with some approximate figures.  That gave me
a reasonableness crosscheck as I started to get my own numbers.  I take
exception to one number in the Velo book on page 33 where it shows the sump
tank at 145 inches.  It is over 150 inches.  The reading comes from the fact
that the gas won't all drain into the sump so using gear wgt numbers on the
scales may not be the most accurate approach for this particular
measurement.  Especially in the RG where the sump is only half the size of
the FG.  Be aware that with any two known numbers you can calculate the
third.  I backed in my wheel numbers (moment)and used the known fuel weight
and the known arm.  

"Been There" Advice:  
	I made the mistake of pouring all the first 20 gal into one tank
thinking that it would level across wings in no time flat.  Wrong.  What I
did was introduce a heavy wing and small bank angle.  It would be better to
put the fuel in equally to each tank then wait a couple of minutes.  Pick a
slow time for the fuel truck man!  Then rocks the wings slightly.   Be sure
you are chocked.    
	I didn't measure the distances from datum to various key points
prior to putting the aircraft on the scales.  Points like wheel axel points,
aprox wgt centers for front seat, rear seat, spots you have earmarked for
Jepp bags, door cubbyholes, you name it.  (Like what's the exact measurement
of the aft lower corner of the entry door?)  It is much harder to do this
with the aircraft on scales.   All these can be done easier with a plumb bob
and marking spots on the hangar floor then record them all on a sheet of
paper before you begin.  All this for a reasonableness crosscheck as you do
the measurements.  You will need to know all the other distances the day you
load the airplane for a trip to grandma's.  Good idea to get them now.
	Leveling:  My airplane as it sat empty on the hangar floor was nose
high.  I should have thought to shim the main wheels with a pc of plywood as
I mounted the airplane on the scales.  I didn't.  
	You can let air into or out of the tires within a range to get the
pitch and bank level numbers you need.  A friend on hand suggested that and
it worked great, with this exception.  If you have the nose tire down to
complete deflation as you add wgt the side walls will compress on you some.
The wgt change on the nose from empty to full is about 50 pounds.  
	I did my fuel probe calibration at the same time to include marking
my cabin sight gauges and a dip stick.  That's a lot going on at once.  Make
yourself a checklist.  Or be ready with siphon pumps and barrel for
oversights!  
	Check BOTH tanks as you add fuel with the dowl stick from the
hardware store.  I had a wing to wing wgt imbalance as the night went along
that didn't affect the CG, but was a puzzle to me until I realized I had a
small wing droop (gear flex?)  that didn't show up much on my centerline
mounted digital level in the aft cabin.    For the XL: for me:   the dip
stick for me came out at 1 inch equals 5 gallons or close enough from empty
to full.

Terry

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Douglas Holub
Sent: Monday, November 10, 2008 11:39 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Weight and Balance Levelling

Hi Brian,

I'm planning on doing mine this week, too. I think I'll write down what I'm 
planning to do just FYI, and also to help organize myself.

My fuselage came with a fore-aft level line. When the work on the kit began,

little plastic bubble levels were epoxied to the fuselage to make it easy to

level the fuselage fore and aft. When it came time to prime the airplane, 
before I removed those little plastic levels I leveled the plane and drilled

two small 1/16" holes which were level and about 2 feet apart located below 
the strake on the right side of the fuselage. Now when I want to level the 
airplane, I stick two 1/6" drill bits in those holes and lay a carpenter's 
level on them. (I got the idea from someone on the Reflector, but I forget 
who.)

I've already leveled the plane and used a tape measure and a plumb bob to 
find the arm of the nose wheel axle and the main gear axles. Mine is 34.5 
inches and 133.5 inches with the nose of the fuselage being zero.

The W&B procedure in my Velocity Owner's Flight Manual says to weigh the 
airplane empty with no fuel in the sump. Makes sense to me. I'm mildly 
curious to know how the CG would be affected if I ever ran the sump dry. 
I've got a 6.5 gallon sump, so it probably makes more of a difference in my 
case than in yours. I've got an old Jaguar with two selectable 12 gallon 
fuel tanks. We ran the car on one tank until it was dry. We'll drain the 
fuel currently in the Velocity into the Jaguar and a gas can and weigh the 
plane when it's empty, then use a siphon hose and the gas can to put 6.5 
gallons of fuel back into the airplane and record those weights, then fill 
the tanks up and record the weights again. I may also record the weights 
when the tanks are half full, because I think the fuel tank moment might 
change a little as the tanks are filling.

The rest is easy.  While the plane is on the scales with no fuel on board, 
I'll weigh my son and then sit him in the pilot's seat and record the 
weights, sit him in the co-pilot's seat (it is staggered about 2" back from 
the pilot's seat) and record the weights, then put him in the back seat and 
record the weights.

Doug Holub
Standard FG w/ electric nose lift

----- Original Message ----- 
From: "Brian Michalk" <michalk at awpi.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Monday, November 10, 2008 9:44 AM
Subject: REFLECTOR: Weight and Balance Levelling

> I'm planning on doing my weight and balance this weekend.
>
> I have not brushed up on exactly what needs to be done for the process,
> so I am starting here.
>
> 1)  I'm assuming I need to level the plane fore/aft.  What points do I
> use for levelling?  left/right is easy.
>
>
> 2) I plan on measuring with full sump as baseline.  Add fuel in
> increments.  Also do a W&B with pilots.  Of course all interior and
> accessories are installed.  The plane is close to a "flying condition".
>
> 3) A buddy is bringing over his Cessna 210, and we're going to use that
> for the fuel, and then return it after we are finished.  I have not yet
> done fuel flow testing, and did not want to mess with a full load of
> fuel in the plane.
>
> Any comments on procedure?
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