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Old Feb 16, 2010, 10:17 PM
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Don,

Thanks for the kind words!

VIKING
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Old Jun 03, 2015, 06:15 PM
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Reviving the SOARBIRD 4 design project

Friends,

After working on the KFm airfoiled SOARBIRD 4 project several years ago, I had set it aside to work on other KFm variant designs to see if I could develop techniques to minimize drag and improve power-off glide efficiency. The DANCER series of designs resulted in a lot of progress.

http://www.rcgroups.com/forums/showthread.php?t=860461

After having cataract surgery completed with excellent results late last year, I'm once more seeing great (excellent distance vision without glasses for the first time in my life!) & able to once more do the flying and flight analysis.

So this morning I brought out the SOARBIRD 4 wing and completed some modifications, converting it into a variant of the KFm3P airfoil which has proven itself so effective on the later DANCER 3-4-5 designs. The photos below are a recap of this wing's design & modification.

I'll be doing some test flying to verify the optimum wing to H. Stab. incidence angle for most efficient glide before completing the new fuselage; the rough-out profile is shown in the last photo below. I'll post the results as this project progresses.

Viking
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Old Jun 03, 2015, 06:26 PM
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Viking60....

That is great news to hear that you have recovered your vision. It is amazing what medicine and science can do these days. I had two knee replacements done two years ago and it has made a world of difference for me.

~ Dick
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Old Jun 04, 2015, 09:31 AM
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Dick,

Thanks- it's really wonderful what they can do!

This SOARBIRD 4 wing prototype is about 8.8% thick, but it does have a somewhat fat folded leading edge area that could have benefited from further airfoil shaping work. If I were to build another similar wing, I'd do more foam thinning in the leading edge area before assembling the wing. The wing structure cross-section diagram below is from the DANCER III and V wings which are gliding very efficiently.

VIKING
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Old Jun 04, 2015, 01:44 PM
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Friends,

The SOARBIRD 4's modified KFm3 variant wing is now gliding nicely after the last modifications; the 3mm thick angled panel running from the primary step back to form the 3mm high secondary step at ~75% of chord is working nicely!

For today's flying, I mounted it on the original 'Slim Beagle' fuselage from early 2007.

This fuselage is shown in the second photo with the 33" span KFm3 "HOT DOG" wing, which I'm told by Tony & Dick was the first KFM3 wing to ever have been flown. It's still flying great & a fine fun flying wing option! The posts from back in 2007 are on this page on my web site:

http://www.stenulson.net/rcflight/sl...20Wing%20Build

FLY!!!

Viking
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Old Jun 04, 2015, 03:48 PM
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Bruce...

Through the years, you have done a great deal of work to enhance the efficiency of the KF Family of Airfoils. You have significantly influenced the acceptance of this rather counter-intuitive approach to generating lift. There is always great resistance to any new idea. You were willing to experiment and improve this idea. For this, I will be forever grateful.

~ Dick
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Old Jun 05, 2015, 07:45 AM
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Dick,

Thanks for your kind words! It's been my sincere pleasure to be a part of this process.

Proof of concept through experimentation is a progressive process; theory is fine only up to a point- as a starting point. So we build a prototype to test any theory, then make a series of progressive modifications to work towards the performance objective.

I'm glad to have been able to share what I've observed during this process, while doing my test flying in our ~70% density air here in Colorado's high country. (Aerodynamic 'shortcomings' seem to be more apparent in these flying conditions... Some aircraft said to 'fly great' at sea level don't handle worth a pinch of squirrel scat up here!)

Dancer III and IV were produced to minimize fuselage contributions to total airframe drag so that variations in wing airfoil profiles could be better evaluated. The power-off glide efficiency and wind penetration capability is what I focus on.

Enjoy The Journey!

Viking
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Last edited by viking60; Jun 06, 2015 at 07:52 AM.
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Old Jun 28, 2015, 09:58 AM
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Glad to hear your sight is top notch now. Hope you continue with Soarbird, a great flyer to keep going.
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