Nose weight

Tue Mar 15 14:14:55 AKST 2005

To calc the CG shift:

Define a datum, any point from which all measurements are taken.

Measurements to the left of that point are negative, and to the right are
positive.  (Use the tip of the spinner and all measurements will be
positive.)

So you know the weight (say 280 oz) and you know the CG as measured from the
tip of the spinner (say 25”).  If you stick a 5 oz weight 6” to the right of
the datum (spinner tip), the CG will move .33” forward.  This is calculated
by using Weight * Arm = Moment where Arm is the distance from the datum:

          W     A    M
EWCG     280 * 25 = 7000
Ballast    5 *  6 =   30

Sum the Weights and Moments and solve for the new Arm:
7030 / 285 = 24.67

So the CG went from 25” aft of the spinner tip to 24.67”

If you pick the current CG as the datum, then it becomes:
         W       A     M
EWCG    280  *   0  =   0
Ballast   5  * -19  = -95
       ====          =====
Total   285           -95

A = -95 / 285 or -.33

So again, the CG is moved .33” forward.

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of John Ferrell
Sent: Tuesday, March 15, 2005 10:11 AM
To: discussion at nsrca.org
Subject: Re: Nose weight

Make a mold from aluminum foil to go inside the fuselage around the nose
ring.
melt the required amount of lead in a can with a propane torch.
Pour lead into mold
Either glue or screw the weight in place.

Channel locks work better than straight pliers to handle can.
Lead may be trimmed with pocket knife.
Silicon (bathtub caulk) is easy to use and remove, but has a 24 hour cure
time.

Has anyone put together the math to figure out how far from the cg how much
weight is needed to move the cg how much?
Knowns:
    current cg
    current airplane weight
    weight to be added
Find distance from current CG...
Or from a reference point?

John Ferrell
http://DixieNC.US

----- Original Message -----
From: "Steve Wiggin" <swiggin682 at cox.net>
To: <discussion at nsrca.org>
Sent: Monday, March 14, 2005 6:26 PM
Subject: Nose weight

>I have to add about 2 1/2 oz of weight to the nose of my pattern plane for
>static balance. Has anyone ever tried pouring molten lead into an aluminum
>spinner to get the weight as far forward as possible? I would probably have
>to epoxy the weight in place and balance the spinner/weight, and wonder if
>this would cause undue stress on the engine bearings. Any ideas would be
>appreciated.
> Steve
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