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Aug 25, 2019, 06:59 PM
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Thor F3 res plank


My wife reads all the time and it's one of her big passions, oh and art too.
Some times paint drying metaphores are used to describe my hobbies. I gess I understand, I also enjoy art.
Mine is teaching how to match the hatch in flyfishing for trout and RC gliders. Last year I was able to land the biggest rainbow trout of my life in my float tube while fishing in Crane prairie RES here in OR with a dragon fly nymph on a #8 hook. Now I no longer (need) to catch a big trout like that but flyfishing is still very, very enjoyable even though I've met my life's goal.
Now it's just do the 1/3 scale Carbon Dragon sailplane and this flying wing both from scratch. Then back to slope flying and who know's what.
No more side notes I promise.....
Any way I need to start cutting out parts for the vertical finn and glue it up.
More photo's on the pod.
Kyle
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Aug 25, 2019, 07:17 PM
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Thor F3 res plank


I did learn how not to rush the process. I started to be conserned when I found a glitch, not knowing how this thing would truely wiegh and if it was going to be too fragile. Then I remembered this pod will be lightly fiber glassed when completed.
I was just over thinking it. Again...
All is fine here in Oregon.
From the neighbors accross the street.
"See that light on in that garage..Yes he's back at it again.. Those sailplanes. What a nother one?
Ya, it just never seems to end...."
More photo's... The white one completed is a wonderful flying RES that Peter W talked with me about. Great video.
Aug 26, 2019, 06:42 AM
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EdSoars's Avatar
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Kyle, your side notes are what it's all about. The lure of flying model sailplanes is usually impossible to explain to someone who isn't also infected by the virus. It may be in part because the lure is different for almost everyone. I understand the lure of a beautiful built-up sailplane, but choose not to use the method, or I'll never get to fly between builds and repairs!

Wait a minute: some of our local coyotes are yodeling outside the open window. It's just barely breaking dawn here in the Central Rockies, and the chorus is as wild and sweet as swinging a sailplane around in a boisterous thermal. Which is also as sweet as twirling a pretty girl around on the dance floor. Okay, there's my metaphor... pass it on to your wife.

Okay. I actually have a plank-related question: how to figure the vertical tail volume? It has to be closely related to the span, with a smaller input from the wing area, so maybe the aspect ratio figures in the equation somehow. And is it the same as for a conventional wing with a horizontal stabilizer? Many planks seem to have small fin volumes relative to their spans/wing areas.

Onward thru the fog,
ed
Aug 26, 2019, 11:02 AM
You know nothing....
Stuart A's Avatar
Quote:
Originally Posted by EdSoars
Kyle, your side notes are what it's all about. The lure of flying model sailplanes is usually impossible to explain to someone who isn't also infected by the virus. It may be in part because the lure is different for almost everyone. I understand the lure of a beautiful built-up sailplane, but choose not to use the method, or I'll never get to fly between builds and repairs!

Wait a minute: some of our local coyotes are yodeling outside the open window. It's just barely breaking dawn here in the Central Rockies, and the chorus is as wild and sweet as swinging a sailplane around in a boisterous thermal. Which is also as sweet as twirling a pretty girl around on the dance floor. Okay, there's my metaphor... pass it on to your wife.

Okay. I actually have a plank-related question: how to figure the vertical tail volume? It has to be closely related to the span, with a smaller input from the wing area, so maybe the aspect ratio figures in the equation somehow. And is it the same as for a conventional wing with a horizontal stabilizer? Many planks seem to have small fin volumes relative to their spans/wing areas.

Onward thru the fog,
ed
I seem to dimly(best I can do these days) recall an article by PW on the subject of tail volume/shape etc.Possibly Soaring Digest?
Aug 26, 2019, 01:31 PM
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EdSoars's Avatar
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Thanks Stuart. I found a vertical tail calculation for conventional gliders on TailwindGliders.com. For whatever reason, it looks like the volumes are larger than for planks.
Aug 26, 2019, 03:39 PM
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Stuart A's Avatar
Here’s one article.There are two more
http://www.rcsoaring.com/rcsd/RCSD-2006-03.pdf
Aug 26, 2019, 09:41 PM
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EdSoars's Avatar
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Woo Hoo, Stuart! Thanks! I've about decided that the First Winter Project for 2019-2020 will be the FABULOSO Peter Wick Amokka 202 in hotwire foam format. All the videos of that wing in flight are stunning.

But OMG, cutting EIGHT templates and hot-wiring six cores for that wing. Sigh. But by that time, Kyle will have finished his beautiful creation and be posting gorgeous videos from Oregon for our inspiration.
Aug 27, 2019, 07:42 PM
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Thor F3 res plank


You got me intreaged so I watched about an hour of that Amooka on youtube. Extreamly efficient, fast and oh so beautiful, with not really any energy lost in those turns at all!
I will always remember flying with a friend of mine long ago, a flying wing of 50 inches at the AMA max alowable wingloading on the slope some 25 years ago. First he put in a pound of lead, then 2 pounds and this little wing in 20 mph plus slope wind just did it! What ever you could dream of. Sooooo much like the big brother Amooka now but not anywhere near as pritty though. And that friend of mine Rolf Zurcher was having the time of his life. Those were the days we would load up the car with every conseivable flying glider from no wind ultralight hand launchers to 160 inch slope ships. Drive to the top of that mountain and have no clue when we were coming home that night. Some times no wind and you just heaved that thermal ship off the top hopeing for thermal, com-mon thermal.................. Thermal!!!! The anticapacion the loss of hight with only large jagged rocks every where and then like the thermal gods slapped that plane really hard, a huge wall of upwardly moving thermal.
Or sooooo much wind you had to think very clearly where the lead was and were you really prepared or just fooling yourself. Was the thing you were gona fly gona really fight that wall of wind? Or are you just nervous because of the car was actually rocking due to the gale force 40 mph wind. So much time has gone by and I seem to just keep watching the turkey vultures every spring wishing I was flying right then.
So I started to cut finn ribs last night and you know what, I rejected half of what I cut out. I was fitting them to the main spar and leading edge and they would not line up. That's fine I'm determend and not ever gona stop trying......
I found this beautiful pic of a MAX plank that I saved for inspiration. I also enclosed this pic of some of the Porland Area Sailplane Society members and I at a F3 res competion. I'm the one with the red winged plane that has a really skinny white fuse and an all flying stab. Its a Yellow Jacket competition wing and my own fuse and tail. Flies real nice I'm hope this Thor F3 res flies as well as this one....
Kyle
Aug 29, 2019, 04:01 AM
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Here is a formula that I have used for many years to calc. the tail-volume for planks.
Normally I use the factor 42 (STFs) for the stability (lower factor means more tail volume)
The other factors are:
b/2 is half span
F is the wing area
Fs is the tail area
and xs is the distance between the neutral points of the wing and the neutral point of the tail . for an approximation you can use the t/4 point at the average chord of the wing / tail respectivly

if you choose higher numbers of xs it will give you more damping (probably good for faster wings - straight flight and less tail area) and I would choose lower figures for xs for thermal planes (the windfreak is good example)

hope that helps

yours Peter
Aug 29, 2019, 07:25 AM
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EdSoars's Avatar
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Peter, that is exactly what I need. I'll use it on the current PsiClone build thread.
thanks!
ed
Sep 15, 2019, 10:21 AM
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Thor F3 res plank


I used the formula as close as possible and I came up with a 41.78 for my newly built tail and wood boom extension. Not quite the 42 but close.
I took a week of vaccation off and imeadiotly started work on the finn and wood tail boom when I came back home. I had to throw out all the ribs I had cut and rethink how to make a un-twisted structure with the strength I believed was required for the kind of thermal flying this is intended for. The spar in the middle was too large as well as the leading edge. The trailing edge was too fragile and over all I had to do alot of thinking. I looked at how the F3 res planes tails are made that are light wieght and have a good airfoil as well as durable.
I reselected a spar, CF tube 3.2 mm dia.
Leading edge CF rod 2.15 mm dia
1/16 sheet basswood for trailing edge and top of finn and the base ribs ( last 3).
1/16 sheet balsa wood for the remaining top ribs.
I secured down the trailing edge, top peice, spar and leading edge. Then did the unthinkable I cut rib blanks with spar gaps and glued it all together. Then filled over the gap after the spar was glued in. Then hand sanded the ribs to contour. Not at all how I imagined this would go but it came out straight true and strong not to mension 8.5 grams for the finn and 6 grams for the wood tailboom. The tailboom is 12 inches long.
The tailboom is much longer than I wanted but I put in the # on the formula and had to lengthen the gap between the tail and the wing from 3 inches to 6 inches. The tailboom is made from 1/4 inch sheet contest balsa scrap I had in the shop on the sides and basswood, 1/8 x 1/8 inch square, top and bottom stringers as well and 1/64 sheet ply wood scrap. I wanted to transfer the load from the basswood stringers to the tailboom and the tall finn will want to break just at the point in front of the leading edge and the very light plywood does this great. The 1/4 inch contest balsa was sanded down so the 1/64 plywood could be flush when glued in place. Then the basswood stringers added and then both sides carefully glued together. It was glued up with good tight fitting joints and sanded down to a taper. Then rounded and some shaping. I am very happy with the results and I am extreamly pleased with the fact that it's not unpleasant to look at. Some times I rebuild a structure when I know it's a mess and not done right.
Sep 15, 2019, 10:26 AM
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Thor F3 res plank


I took a lot of photo's so if I go over board some one please put up a stop sign and call the photo police.
Sep 15, 2019, 10:30 AM
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Thor F3 res plank


Just a few more of those boaring photo's from "Ol" Kyle.
Sep 15, 2019, 10:38 AM
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Thor F3 res plank


Word of warning balsa chips, dust and chunks are mostly what this is about so sheild the eye's of those under age and not prepared for this kind of stuff. Hours of thinking, drawing estimating, carving, cutting, glueing and not to mension waiting for stuff to set up.
Thrilling to some and soooo boaring to others.
Sep 15, 2019, 12:39 PM
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Stuart A's Avatar
Very nice!Keep them boring pics coming


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