Bill,
I use grams/inch for the unwound, freshly stripped strand. Once the strand
becomes knotted and made into a motor, I abandon the grams/inch data and use
only the loop length as a reference. This applies only to F1D where there is
a motor mass restriction. For other events where there is not a motor mass
restriction, I am still at a loss for how to measure this. For my F1L motors
at USIC, I used the grams/inch as a starting point to determine the cross
section of my strands. It helped me to understand how much a 15 inch loop
would weigh.
I find that there are as many ways to measure a motor as there are styles
for winding them. I like to break in a motor before I wind to full torque,
however I have read that some people get the max torque out of the first
wind. I have also found that there are people who require their motors to
rest for up to 24 hours between windings. If I did that, I would never get
one on a plane!
On Wed, Jun 2, 2010 at 4:41 PM, Bill Gowen <wdgowen_at_gmail.com> wrote:
>
>
> Ben
> Do you use the grams per inch for the strand or for the motor?
>
>
> ----- Original Message -----
> *From:* Benjamin Saks <bensaks_at_gmail.com>
> *To:* Indoor_Construction_at_yahoogroups.com
> *Sent:* Wednesday, June 02, 2010 4:10 PM
> *Subject:* Re: [Indoor_Construction] Re: Motor weight, size density?
>
>
>
> 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
>
>
>
--
BEN SAKS
www.bensaks.carbonmade.com
Received on Wed Jun 02 2010 - 13:56:32 CEST