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Author Topic: New F1d build...rubber starting questions  (Read 431 times)
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Jwerner
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« on: May 06, 2019, 10:50:18 PM »

Any tips on a starting point for a new F1d flier on rubber sizing etc?   I don’t expect to do much more than short hops this Friday, but I really have no idea where to start
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ykleetx
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« Reply #1 on: May 07, 2019, 01:17:19 AM »

It really depends on your prop diameter/pitch and the height of the site.

For some references, look here: https://indoornewsandviews.com/

and search for F1D. You will find lots of F1D plans with the rubber sizes that are used.
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Jwerner
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« Reply #2 on: May 07, 2019, 08:13:00 AM »

Thanks.  Been all over there.  I guess I am confused about the new .4 g rule and how that interacts with the older rubber sizes.  I followed one of your plans actually lol.  I think the plane you used in 2015 in Kent (away from workshop so not sure name).  The rubber size was “.4 5/99”. 

I guess my question is simpler.  Is the standard simply to use spacers with a smaller loop now?   I cut a bunch at various sizes around .03g per in as that seems what many have recorded.  Seems with a 8.5 hook to hook that would require about a 2 in spacer. 

Site has a 42 ft ceiling, though I don’t expect to get anywhere near there.  No way to steer yet.  3 props from 18.25 -18.5, all 27-28in pitch on the low side.  Planes are around 1.4g for my lightest to 1.6 for my first one (including spacer).   My motor sticks are still coming out too heavy at .45.  Rest of the models are really close to weights listed. 

Will see how it goes!
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f1dguy
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« Reply #3 on: May 10, 2019, 04:43:00 PM »

Using spacers is usually required if the hook-to-hook distance is >8" or so.  For O-rings a hook-to-hook of 7.5" is working for top flyers.  The question is whether you have existing longer motor sticks that you don't want to discard.  If you do, spacers will work.  If you are building new and are a relative beginner then shorter would be advantageous since the stick would be lighter, you don't have to account for spacers as model weight when you may already have challenges making weight, and there is less stress on the airframe with a shorter stretch.

There is a school of thought that says stretching the motor is in itself beneficial.  But in general to access that benefit requires a lot of stretch. 

Another factor is where you will be flying.  Lower sites require thicker and shorter loops.  A site like Lakehurst or Slanic would require very thin rubber and longer loops.
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jakepF1D
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« Reply #4 on: May 17, 2019, 03:08:10 PM »

Site has a 42 ft ceiling, though I don’t expect to get anywhere near there.  No way to steer yet.  3 props from 18.25 -18.5, all 27-28in pitch on the low side.  Planes are around 1.4g for my lightest to 1.6 for my first one (including spacer).   My motor sticks are still coming out too heavy at .45.  Rest of the models are really close to weights listed. 

Will see how it goes!

If you're planning to fly full motors in a 42 foot site, and your models are 1.5-1.6g with spacer, you'll need something thicker than 30mg/in.  Kang used 33.8mg/in for his Cat 2 record with a model that was right at the minimum.  You'll probably want to start with something like 35-36mg/in and see how it goes.
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mkirda
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« Reply #5 on: May 25, 2019, 09:29:49 AM »

Try for 5.5" to 6" loops overall for Cat2. Make a number of motors in that range. You'll probably end up setting on 5.75" or so.
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