Gary Hodson, Kurt Krempetz, Indoor or Outdoor Contest Board, and All,
I have occasionally flown both indoor and outdoor cat gliders and have measured and done computer modeling of energy stored by stretching a few different rubber batches with loops of various length and width. Therefore, I vote with Kurt Krempetz. No rule on rubber is needed for indoor, or even for outdoor. The existing outdoor cat glider rule is truly bad, because it says, but probably does not mean, that an 18-inch length of rubber must be used to form a loop. It does not state that this is the maximum length of rubber that may be used. Unless you have the arm length of Yao Ming, neither you nor I can fully stretch a 9-inch loop of rubber, even if you have saved rubber prior to the advent of Tan 2 from FAI Model Supply. For me, a 5- or 5.5-in loop of rubber is about right for older rubber. Tan 2 and later rubber is perhaps 10% more stretchy and requires a shorter loop.
I have always interpreted the outdoor rule to mean that an 18-inch length of rubber (or approximately a 9-inch loop) is the MAXIMUM amount that may be used. Some cynics at the USIC have stated that you must use 18-inches of rubber, but if that is too long for you to stretch properly, you can merely choke up on the length actually used or wind some around the launching stick. Clearly that is a ridiculous rule that we do not wish to imitate for indoor cat gliders.
Any rule should allow for changes in rubber availability. I believe that Kurt Krempetz is correct.
Fred Rash
_____
From: Indoor_Construction_at_yahoogroups.com [mailto:Indoor_Construction_at_yahoogroups.com] On Behalf Of Kurt Krempetz
Sent: Wednesday, December 05, 2007 1:12 PM
To: Indoor_Construction_at_yahoogroups.com
Subject: Re: [Indoor_Construction] Re: Free Flight Rule Proposals
Hi Gary,
The rule proposal you stated below is for outdoor
catapult. Indoor catapult has no limit to the amount
of rubber you can use. I'm not aware of any rule
proposal changes for indoor catapult.
Personally I think this whole rule should be
eliminated and outdoor should be like indoor, no limit
on the rubber. My experience is that the rubber band
or the amount of power you can put into the glider is
not really the controlling/major factor for getting
height. Drag is the real factor. My typically
Category 3/4 indoor gliders can get up to about 100 ft
on one loop of 1/4. Shooting them up with 2-loops of
1/4 gets me about another 15 ft. I have experimented
with this on some outdoor models and if one eliminated
this rudder restriction rule I would probably be using
3 loops of 3/8. From my testing I estimate a gain of
about 20 ft in height. I think most people can pull
back 3 loops of 3/8 so I not sure why the rudder
should be limited. Also for outdoor gliders,
shooting up in good air is easily another 30 ft in
height. In outdoor gliders it all about the air.
So I am "neutral" in regards to this rule
proposal. I have been to many outdoor
competitions(include many Outdoor Nationals) and I
never had my rubber band measured. I am not trying to
encourage that one starts measuring bands, because I
think it would be a waste of time and energy.
Well that my 2 cents on the subject,
Kurt
--- Warthodson_at_aol. <mailto:Warthodson%40aol.com> com wrote:
>
> Jerry,
> I will be replying to your email in a few days, but
> in the meantime I would
> like clarification to the rules change below. Also,
> I have sent this to some of
> the freeflight lists in hopes of receiving input
> from some of the glider
> fliers.
> The rule seems to assume that all rubber is 1/16"
> thick, which of course is
> not true.
> Does this change mean that you can use rubber with
> the equivalent of 1/4" X
> 1/16" crossectional area (0.0156 Sq. In)? For
> example, if the rubber is 0.040"
> thick, can you use two strands that are each .195"
> wide?
>
> Also, in the second paragraph below, where it says
> ....."(or equivalent, i.e.
> two strands of ........." shouldn't that read FOUR
> strands.
>
> This proposal is poorly written. Will there be an
> opportunity to clarify the
> wording, or do we have to accept it exactly as
> written?
> Thanks,
> Gary Hodson
>
> In a message dated 11/27/2007 6:04:21 PM Central
> Standard Time,
> jb_murphy_at_msn. <mailto:jb_murphy%40msn.com> com writes:
>
> OFF-09-3 – Allow options on the size of rubber
> used in the Catapult Glider
> event, equivalent to ¼†x 1/16†currently
> specified.
>
> Free Flight Outdoor Catapult Glider 4.1:
> Change: and a two-stranded loop of ¼ inch flat
> model airplane rubber (FAI,
> Pirelli, etc.) made from a piece that is 18 inches
> long
>
> To: and a two-strand loop of ¼ inch (or equivalent,
> i.e. two stands of 1/8â€x
> 1/16â€) rubber (FAI, Pirelli, etc.) made from a
> piece(s) that is 18 inches long.
>
> Logic:
> ¼ inch rubber is going away. The standards are now
> 1/8 inch and 3/32 inch.
>
> Submitted by: Faust Parker, AMA #15980
>
>
>
>
>
>
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> [Non-text portions of this message have been
> removed]
>
>
Kurt Krempetz
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Received on Wed Dec 05 2007 - 11:08:50 CET