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Old Mar 25, 2012, 11:05 PM
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United States, NM, Albuquerque
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Analytical solutions with the level of anisotropy found in composite layups would be difficult to arrive at, much less reproduce during fabrication. Perhaps you could get some experimental (modal) results of different layups using a laser-doppler velocimeter? The modal shop also rents accelerometers and modal hammers if you wanted to do a simple modal test to get FRFs.

I submit that perhaps there is some coupling between the boom's fundamental modal frequency and the aeroelastic or vortex shedding behavior of the stab that could be exploited.
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Old Mar 25, 2012, 11:30 PM
Jim C
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42 Tom. nice lateral thinking.
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Old Mar 26, 2012, 07:32 AM
Father of Fr3aK, DLG Pilot
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USA, OH, Worthington
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I'm not sure how consistent my materials and processes are yet, but it looks like there may be some real benefit here. Obviously I will be testing more.

I pulled three more sets of tails this past weekend and all were under 13.5 grams. So much of that process has changed that I think I should post a new video

I have also been playing with the seaming method on my fuses and have peeled about five to ten minutes from that layup. Every little bit helps.
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Old Mar 26, 2012, 10:47 AM
2013 US F3K Team Manager
Newbury Park, CA
Joined May 2005
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Tom, have you tried to validate the launch difference with a different thrower? It is possible that you effectively tuned your fuse to your specific throwing style, but that may not help someone that launches with a slightly different style? Maybe they need that kick point a little further out, or closer in...

-l
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Old Mar 26, 2012, 11:13 AM
Father of Fr3aK, DLG Pilot
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USA, OH, Worthington
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Yes, it's very possible Lex. Could we be buying our DLG fuses with a "tour stiff 100" or a "85 flex" rating in the future?

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Old Mar 26, 2012, 11:30 AM
Just fly it!
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Cody, WY
Joined Nov 2007
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Tom, is it possible that the way that canopy was taped on was different. I know that when I had some people testing my fuse they found out that the way the canopy was positioned and sealed would effect launch height. I don't think that it was effecting the actual launch height but rather how the altimeter was taking a reading. Fluctuations of 20' could be attained by just fiddling with the canopy seal.

BTW, in no way am I trying to discredit your findings. You could very well be onto something very significant. I just don't trust those pesky altimeters.
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Old Mar 26, 2012, 12:39 PM
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I don't trust them either, but no... The canopies were the same.
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Old Mar 26, 2012, 01:26 PM
Throw it like you hate it
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United States, CA, Castro Valley
Joined Apr 2007
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Tom
Awesome empiricism! Where did the 6gr weight savings happen with the new fuse? If the weight savings came from the extremities, could this lead to a reduction in the amplitude of the yaw excursions on launch, leading to increased launch height? Also, does moving the kick point farther aft effectively make the boom stiffer by shifting the bend profile? Some static deflection tests with a load at the tail would be interesting to evaluate as well. I like your pursuit of "free" launch height. Can I have some as well?
Paul
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Old Mar 26, 2012, 02:17 PM
Father of Fr3aK, DLG Pilot
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Extremeties are a pinch lighter Paul. I took some material from the boom in general and replaced it in certain places and with layers.
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Old Apr 05, 2012, 09:39 PM
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Tick tock. tick tock.
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Old Apr 09, 2012, 08:22 AM
Father of Fr3aK, DLG Pilot
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Different tail shape for testing with the same airfoil, slightly thinned, and about 8% larger...
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Old Apr 09, 2012, 09:34 AM
Jeff Carr
Ft. Mill SC / Charlotte NC
Joined Mar 2001
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I like that. Should help in the launch

Jeff
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Old Apr 11, 2012, 08:51 PM
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Australia, QLD, Gold Coast
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can you send a set of those tails to Australia ?? PM was full
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Old Apr 11, 2012, 10:15 PM
usaf3kteam
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Tom that looks great
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Old Apr 12, 2012, 11:38 AM
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United States, NC, Raleigh
Joined Sep 2010
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Tom, amazing work as usual. I like the look of the new tail... go big!

Eric
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