I use grams/inch for my F1D motors. I find it much easier to hit the target
of .6 grams for a motor when I know the weight per unit length. That allows
me to do simple math to predict the length for a full motor. I agree with
Kang about the variable thickness in the TanII and Supersport batches. I
have seen this range in .010 plus minus, so measuring only the width is not
accurate enough.
On Wed, Jun 2, 2010 at 4:01 PM, Yuan Kang Lee <ykleetx_at_gmail.com> wrote:
>
>
>
> I would prefer to use what most people use, which seems to me to be just
> the width of the motor in thousands of an inch. E.g., .025" for a light EZB,
> .080" for LPP, etc. I talked with other experienced flyers at USIC,
> including my Pro partner, Tom Sova, and all refer to rubber sizes this way.
> In all the plans I've come across from the U.S. and U.K., rubber motors are
> indicated this way. E.g., ".025 x 12", ".050 1.25g", or ".042 x .055 x 15.5
> 1.075g" -- that is, all describe the width of the rubber in .001 inches.
>
> I only recently, about 2 weeks ago, started stripping my own rubber. There
> are two main reasons I am currently using g/in to measure rubber instead of
> using the width of rubber in .001 inches:
>
> 1. the Harlan rubber stripper does not output a rectangular cross section
> -- it is trapezoidal. It's difficult enough for me to measure rubber's width
> when the cross section is rectangular. With a trapezoidal shape, I would
> have to measure the long and short bases of the trapezoid and take the
> average. Yuck. This is the first reason I went to g/in.
>
> 2. I've found that the "thickness" of Tan Super Sport to be different than
> that of Tan II. For reference, I was using 04/10 TSS and 03/02 Tan II. Tan
> II's thickness is about 0.042", while that of TSS is about 0.046. If I strip
> the two rubber with the same setting, the stripped rubber has different g/in
> and don't perform the same. Perhaps this is a non-problem, but because I
> primarily use TSS, I wanted to be able to compare TSS and Tan II. This is
> another reason I went to g/in.
>
> But I prefer to use what everyone in the U.S. and U.K. use, if I could
> overcome these two obstacles.
>
>
> --- In Indoor_Construction_at_yahoogroups.com<Indoor_Construction%40yahoogroups.com>,
> Nick Ray <lasray_at_...> wrote:
> >
> > I have been using inches per milligram of untied loop. I think because
> knots
> > are not consistent, and increase in relative mass as the rubber size
> > increases the untied loop is the way to go. The reason I started using
> > inches is because I didn't have meter stick handy. I would say meters are
> > probably better if we wanted to create universal system. I don't think
> using
> > grams or milligrams matters much as its just move thing decimal places
> > around. It would be ideal to use as many significant digits as possible
> in
> > order to get a more precise result.
> > NIck
> >
> > On Wed, Jun 2, 2010 at 1:07 PM, Fred or Judy Rash <frash_at_...>wrote:
>
> >
> > >
> > >
> > > Bill,
> > >
> > > Thanks for all your help on many items.
> > >
> > > I think that everyone will work in grams. Probably we should eliminate
> > > ounces from AMA, NFFS, etc Indoor (and maybe Outdoor) rules whenever
> > > possible.
> > >
> > > The unit for length is harder. Most of Europe and the rest of the world
> > > would argue for meters and probably we should also. I believe that most
> use
> > > g/m of the untied strip. I think in grams naturally from a lot of
> chemistry
> > > lab time as well as model building time, but do not automatically think
> in
> > > meters. I can live with either inches or meters. If I use inches, I
> always
> > > use decimal inches. I never write down a mixed fraction. If I try CAD
> which
> > > I do occasionally, I never use mixed fractions there either.
> > >
> > > I would even be so extreme as to argue that our schools should teach
> > > decimal fractions before mixed fractions. This should start a strong
> > > off-topic thread. <GRIN>
> > >
> > > Fred Rash
> > >
> > > On 6/2/2010 12:41 PM, olbill61 wrote:
> > >
> > >
> > >
> > > I'm wondering if there is any way of describing motor weight per unit
> > > length that is more prevalent than others. The way I started out is by
> > > dividing total weight of a finished motor in grams by the motor length
> in
> > > inches. I think Kang has started using grams per inch for untied strip.
> I
> > > think Leo is using grams per meter.
> > >
> > > Can any others who have switched to weight per unit length describe how
> > > they do it? I'm early in the process of doing it this way and could
> switch
> > > to a different system without much trouble. I'd like to hear from
> English
> > > and European fliers also.
> > >
> > >
> > >
> > > No virus found in this incoming message.
> > > Checked by AVG - www.avg.com
> > > Version: 9.0.829 / Virus Database: 271.1.1/2913 - Release Date:
> 06/02/10 05:57:00
> > >
> > >
> > >
> > >
> > >
> >
>
>
>
--
BEN SAKS
www.bensaks.carbonmade.com
Received on Wed Jun 02 2010 - 13:11:19 CEST