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Old Dec 06, 2010, 11:59 PM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
1,566 Posts
Hmmmmmmmmmmm...

Oooops...




Edit: Tuesday Dec 7, 2010 3:30pm.
I fixed the nose but the wing broke across the chord on the next flight attempt. About 6 tries in the wind and finally the hard crashes and the cartwheel landings did it in. One problem was the popbottle aileron horns. Way too flexible. Popsicle-sticks are the answer. Also I added way too much nose weight and it was not responding to the elevator well at all.
I have video but it's not pretty. I'll spare you that.

New bird plane on the board but with the Taube wing and similar Vee-Tail. No fuselage, just a small pod for the gear. Will make large ailerons for this one and probably use the same Vee-Tail as on the recently deceased bird.
I think this is a plane that will fly well but needs a little more TLC in setting up. anyway I have tons of cheap foam.
Will update!
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Old Dec 07, 2010, 04:49 AM
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Ashford. Kent. England
Joined Feb 2005
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Deltas are better than most in the wind, but what is best is a heavier plane. 20oz + so a big delta perhaps... my best two for windy days are yes..the superfly clone and also a multiplex twinjet (butchered to use just a single motor)
Usually down at 10 oz or so the wind is a pain but my smaller 24" superfly clone is also ok...
Probably any fast plane is going to be better than any slow plane when the wind is up.. and the small superfly is a bit rapid..
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Old Dec 07, 2010, 08:55 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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I guess the original implementation of the Clark Y was flat bottomed for the aft 70% of the chord and the wing thickness was 11.7% of the chord.

With just that much for a description, most people with a passing acquaintance with building and flying would probably come up with similar looking wings.

I think the major difference is the amount of "TLAR" that seeps in for any individual build and the influence of the materials and working conditions.

I have produced some pretty similar wings with the biggest difference being that mine generally had less than 30% curving up to the leading edge, were less than 11.7% thick, and, of course, they were very different on the top of the wing because of the step and what happened to the rear of it.

When I consider the amount of work that it would take to make FFF Clark Y wing and a FFF KFm2 or KFm3 wing, I'll probably go with the KFm build every time.

Jack
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Old Dec 07, 2010, 09:15 AM
treefinder
springer's Avatar
SE MI
Joined Oct 2004
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Jack: the Clark Y profile I found had a straight line from the low point at bottom of section to the TE that I discovered when tracing in Sketchup so I could scale and squash it which sounds just about exactly like what you describe. And I concurr that there seems to be an awful lot of different "clark Y" foils in use. And finally, your last statement is perfect, I when tinkering with a new design always sketch in a KFM wing, just because it's so easy to do and I know it'll work well. The only reason I'm playing with the conventional foil on this redo of the PV2 is the "experiment". Otherwise it wouldn't be nearly worth the extra gluing and sanding!

Ain't it great when we all agree? 8^)
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Old Dec 07, 2010, 11:23 AM
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viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
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Experimenting with variations of wing airfoil shaping is a lot of the fun! We know we can fly a flat plate wing, & by keeping the weight low, we can really have a fun flying aircraft.

And we've proven we can add KF stepped discontinuities to a variety of shapes in a variety of ways, and have benefits to the handling that we didn't have without the KF structure. The process of adding a KF step is fairly forgiving- especially at the power loading factors used these days!

Some people say they can fly a concrete block by putting on a big enough motor, & gluing on some tail feathers, and while they're not technically wrong in claiming that, there may be something that's missing when the "Just throw on a bigger motor" approach is proudly put forth...

There are a lot of 'conventional' airfoils in the airfoil databases which have suitable applications at much higher speed ranges, and only perform when built at much higher Reynolds Numbers.... when shrunk down to typical 'scratchbuilt foamie' size, they just don't perform. And there are also some specific airfoils which do perform very well at low Reynolds Numbers [ which can be simply translated as small wing surface areas, narrow wing chords.]

The actual Clark Y is not my idea of a high performance airfoil... (sorry to those who are fans of it...) I've seen it do a poor job too many times on RC model aircraft- especially up here in Colorado's rarefied air. It's too fat, too blunt at the leading edge, and it's camber line has too much curvature in the rear 50%, making it more prone to boundary layer air separations & high speed stalls... From my viewpoint, it really needs significant reshaping to fly decently when built at low Reynolds Numbers (small foamie scale model sizes.) And it would definitely benefit from having turbulator structures and KF type stepped discontinuities added to it's structure, since what you are starting with just doesn't get the job done very well when built at these sizes. And once you reshape it, it really isn't a Clark Y anymore.

When we start to talk about doing 'comparisons' between 'conventional airfoils' and KF airfoils and calling it 'science', it makes sense to me to start with a 'conventional airfoil' that is proven to perform very well when built in the narrow chord wing sizes that we're actually building. That's why I've mentioned the specific airfoils I listed when Springer asked- (E180, E205, E387, RG14, RG15, MH32).... because starting with a bad wing shape and adding a KF structure to it, then comparing it to the bad wing shape we started with may not really advance our understanding much at all...

(A flying outhouse is still an outhouse...)

You really don't have to make it complicated, & yes, I certainly agree that adding KF type stepped discontinuities can improve handling & performance on a wide variety of designs. But the addition of KF style stepped discontinuity features are not totally 'magic', and there are poorer choices of ways to implement them that have already been demonstrated, too. The idea is to begin to understand more of how to get the best performance & handling from the scratch-built foamies which we build- however simple or complex the build- and that's some of what all of these discussions are really about.

I wish each and every one of you the best of success in all of your efforts! May this approaching Holiday season be a happy time, and may the new year find you healthy & happy!

VIKING
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Old Dec 07, 2010, 01:28 PM
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United States, ME, Windham
Joined Sep 2010
34 Posts
jackerbes,

Sorry, but I just have to chime in here. If you were born in California, and now live in Maine, that does not make you a "Mainah". If you have children born here, they may be "Mainahs", but unfortunately, you can never be a "Mainah". You will always be from away.
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Old Dec 07, 2010, 04:18 PM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
1,566 Posts
Quote:
Originally Posted by davereap View Post
Deltas are better than most in the wind, but what is best is a heavier plane. 20oz + so a big delta perhaps... my best two for windy days are yes..the superfly clone and also a multiplex twinjet (butchered to use just a single motor)
Usually down at 10 oz or so the wind is a pain but my smaller 24" superfly clone is also ok...
Probably any fast plane is going to be better than any slow plane when the wind is up.. and the small superfly is a bit rapid..
I'm thinking Firefly. My Slinger and the delta are both getting a bit spongy in the nose from use and won't last forever. A SuperFly Clone would be good. I started on a new bird plane. I have Gene's Taube wing started and will use a short Vee-Tail, like on the RedKite, with it and make very large strip ailerons for the AET approach. I'll make the nose a bit longer than before for better balance without the need for added weight.

Viking said:
Quote:
"...get the best performance & handling from the scratch-built foamies ..."
That and an interesting look is where it's "at" for me. I'm having fun playing with the airbrush too.

Steve.


Edit:
The bird plane in memorium. See screen-grabs below. Looked good but flew like crap. Totaled before I got the kinks out. My fault entirely. Killed by impatience, don't maiden in high winds!
Just part of the game!
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Old Dec 07, 2010, 05:32 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by arbalest View Post
jackerbes,

Sorry, but I just have to chime in here. If you were born in California, and now live in Maine, that does not make you a "Mainah". If you have children born here, they may be "Mainahs", but unfortunately, you can never be a "Mainah". You will always be from away.
Are you in Maine? Maybe it is a regional rule but the locals will generally accept full time residence for 10 years enough to call yourself a Mainer. Maybe it is the common sense of the fact that if you live here full time and shoulder the same tax burdens they do, that is good enough.

I know all about the "from away" thing. The only cure for it is death. And then the only change is that instead of say "he's from away" they would say "he was from away."

I like it, it is my home, I have mastered all of the winter chores and sports, I'm a Mainer!

Jack
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Old Dec 07, 2010, 09:01 PM
Account Closed
Joined Jun 2009
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Jack... Please tell me that is not YOU!!!
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Old Dec 08, 2010, 12:59 AM
Onward through the fog.
Cybernaught's Avatar
Bohol Philippines
Joined Aug 2008
1,566 Posts
I recognise the first picture.

On a trip to Mexico I had the same affliction as seen in your first picture. It comes from swallowing the ice, made from the local water when you drink large numbers of Margaritas.
They call it "Dihariario Blanco".
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Old Dec 08, 2010, 01:40 AM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
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Quote:
Originally Posted by sharpewing View Post
Jack... Please tell me that is not YOU!!!
I'm sure that guy's just testing a new form of high pressure snow propulsion. I can't see it getting off the ground though
Head
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Old Dec 08, 2010, 07:22 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by sharpewing View Post
Jack... Please tell me that is not YOU!!!
Nope, that's one of my neighbors. He's from away. A Mainer wouldn't be caught out in a silly hat like that.

And that tan line is a dead giveaway too.

He did have part of the disguise about right, the untied boots and the laces flopping would fool some people...

We got that winter wonderland thing going on even as I write this. We have about 6-8" of snow on the ground and it is slowing lightly right now. Some of the them big, slow falling, flakes coming straight down, no wind at all. Almost perfect "during the snow" flying conditions but I prefer the "after the snow" flying.

Jack
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Old Dec 08, 2010, 08:51 AM
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Fairplay, South Park, CO
Joined Sep 2005
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DANCER IV Update: Ailerons & internal battery bay added- build notes

Jack,

I find my aging eyes much happier flying 'after the snow' - when the skies have cleared & the visibility has improved... it's not much fun watching your aircraft disappear up into low-hanging cloud bellies!

Our last snowfall amounted to only 2", and the sun will eat that away soon... I'll be back to bare short grass prairie for my flying surface very soon!

~~~~~~~~~~~~~~~~~~~~

DANCER IV Update

I just completed adding the ailerons to the most recent KF3P glider wing; this is the 'simpler build' 46" span wing. With the 2-3/4" of 'virtual dihedral' provided by the curved upswept wing tips, I have been flying this wing with RET control only for the last few weeks, and it does turn adequately with only rudder working against these upswept wing tips... But now that I had verified this, I find myself fonder of the more immediate & precise attitude / roll control response which ailerons provide- especially useful for higher speed slope flying tasks- so I cut away a set of ailerons 1-3/4" wide x 15-3/8" long from the trailing edge.

Since the Bluecor is normally too flexible & prone to twisting under flight loads without some method of stiffening, I ironed on a layer of the thin lightweight 1.7 mil Doculam clear iron-on covering film, covering all surfaces of each aileron. This stiffened them dramatically, so that they are now very adequate, as far as twist-resistance, for an aircraft of this size / weight. I then tape-hinged the ailerons back to the wing with Scotch transparent 'multi-purpose' tape.

The HXT900 servo was mounted just in front of the wing's CF tubular spar, with the servo's bottom set flush with the wing's bottom surface. The control rods are .032" music wire, which run through a plastic guide tube to keep them from flexing under load. (Aileron control horns are cut from clear 1/32" Lexan polycarbonate sheet.)

I had previously verified the battery mounting position during flight testing by shifting the velcro-mounting position until I had optimum glide & handling; it was time to mark that battery position, eliminate all of the velcro, and cut in a compartment within the EPP foam fuselage where the battery could then be carried inside, out of the (cold) airflow. This would get the battery closer to the lateral center & eliminate the drag of having the battery sticking out in the wind... and minimizing drag on this DANCER IV design has been a lot of what the project is about.

I cut away a snug-fitting pocket in the EPP, then reinforced the foam with more of the iron-on clear covering film- (it really is fairly tough stuff!) I then cut a cover from thin clear plastic sheet, attached & hinged it with tape at the front end, and made a tape latch at the aft end.

The result is that the battery is out of the airflow, closer to center line of the fuselage, protected form the chilling effects of the cold air, and protected from rocks, etc. during rough-terrain landings. And the only aspect left as far as drag is the battery wires & plug extending out, which can be taped out of the airflow on top of the forward fuselage just in front of the wing during flight.

More 'visibility' was then added to the wing, in the form of iron-on Oracover in fluorescent colors, on both top & bottom surfaces. (My aging eyes can use all the help that they can get to keep track of my gliders when hunting & riding thermals several hundred feet up in the sky!)

Final flying weight after all of these final modifications is at 12-7/8 ounces. With 2.3 square feet of wing area, that works out to a wing loading of 5.6 ounces per square foot, which is good for both thermal riding and for slope flying in up to about 25 MPH winds on a wind ship with minimal drag. (Adding ballast is always possible when the winds really get blowing on the slope.)

I'll post a flight evaluation report before long.

VIKING
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Old Dec 08, 2010, 09:00 AM
Addicted to building...
Freddie B's Avatar
Omaha Nebraska
Joined Feb 2006
5,992 Posts
Jack,

I thought that guy was posting because he was a friend ribbing you. Now we know it was your angry neighbor because you shot a photo of him swimming in his Mainah pool! Besides the tan line, shoelaces, a Ginger Ale 'Pop'-cycle would have been a sure givaway too!

BTW, North America had no inhabitants until someone walked the ice bridge from Asia, so we are all from away at some point in the 'great timeline'. Don't know why so many people dislike Californians, since they all want to, and do, move there.

KFm airfoils are interesting, and have some great attributes in many situations. I wanted to thank you for all the great work and time you put in here on this thread, and helping and explaining lots of topics in so many other threads. Although I too have been around a long time, helping newer modelers get on board with a good knowledge base up front is really a cool thing. Not too many people take the time as they should to give the gift of knowledge.

Fred
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Old Dec 08, 2010, 09:30 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Thanks for the kind words, Fred.

I'm just paying back the favors I've received. I came here pretty much ignorant of a lot of the details a few years back and have gotten a lot of help.

As a retired Navy cryptologist and then a gunsmith/machinist/general tinkerer and Jack of all trades I've always been a little anal about the details.

What I did not know then would fill a book, and I love being able to help other along too. They don't have to view my way as the only way, just something that worked for me...

Jack
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