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Building Tips and technical articles. => 1/2 A building. => Topic started by: minnesotamodeler on May 04, 2009, 03:09:43 PM
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Here's what's been occupying my time and keeping me out of trouble lately. A rather large--but light--stunter using a Norvel .061; call it "3/4A".
The "different" aspect: Using that Droopy Diamond airfoil I first tried on a couple of combat wings, where it performed spectacularly...I wanted to see how it would do at slower PA speeds. The principle, remember, is to use diamond-shaped extra-tall ribs widely spaced with no surface spars, and let the covering droop between them, assuming a more typical curved airfoil. The airfoil varies from about 25% at the ribs to around 14% at lowest point between. The last picture shows the droop of the covering.
Span = 34", area 250 sq. in., weight RTF a skosh over 10 oz. Floppy balloon tank inside the cheek. At least 42' lines to start out, I'll probably end up using longer. Check it out.
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WOW! Great job Ray! #^
Where did the end of the main spar go?? n~
Expect a full flight report.
Great looking plane! Well done! y1
"Tight lines!"
Wes
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I like it! :)
I look forward to your maiden report.
Robert
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WOW! Great job Ray! #^
Where did the end of the main spar go?? n~
Expect a full flight report.
Great looking plane! Well done! y1
"Tight lines!"
Wes
HMMMMM, I thought I answered this post...the interior spar ends at the first rib in from the tip, a kind of philosophical wave at weight savings. All the stress is at the root of the wing, not the tip...no need for reinforcement there.
Fer shur, there will be a full flight report whenever it happens.
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Way cool, MM! The size is right, the power perfect, I'll bet you end up between 46 and 48 ft lines. Keep up the good work!
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Thanks Larry, I suspect you're right--I use 48' with my LittleAxe.
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I WANT ONE! That is a cool plane Ray!
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Now don't start hollering "kit it!" until I have at least flown it...
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Front view sure looks strange. The other pictures look great. Spring time should be in your by the end of the month. Let us know how it flies. DOC Holliday
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Front view is a little controversial; something I've wanted to try for awhile, now that I've tried it I'll probably put it to rest. Didn't come out quite as I envisioned it.
"Strange"...I appreciate your tact.
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It is a little 'strange' but I have envisioned this more than once just to be different. Don't be surprised if I have some of mine have the same 'low profile' front end.
Robert
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I WANT ONE! That is a cool plane Ray!
By the way, I neglected to give credit where credit is due...John is the gentleman who first utilized the "droopy diamond" airfoil concept. Show us your green machine, John.
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Hey Ray,
Thanks for the props, but I must say your lines are a lot cleaner than mine. Here's the "Green Giant". Was one of the better planes I ever flew.
(http://i52.photobucket.com/albums/g3/Adduckted/GreenGiant002.jpg)
And my favorite plane ever with diamond wings, "The Confederate". Both of these planes were stolen and recovered in pieces. The confederate was powered by 2 .061 AP Wasps and was a joy to fly.
(http://i52.photobucket.com/albums/g3/Adduckted/pics009.jpg)
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You gotta build another Confederate, that's a cool plane.
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I've thought about it, but I'm down to only one engine and money's tight right now. It was a fun plane to fly, it had the prettiest takeoffs and landings of any plane I ever built, guess I got the ballance just right on the trike gear. I think it had a 42" span and weighed in aaround 17 oz.
(http://i52.photobucket.com/albums/g3/Adduckted/pics008.jpg)
(http://i52.photobucket.com/albums/g3/Adduckted/planes/pics007.jpg)
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Flight report?
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Not yet, been too windy here, now that it's finally settling down I have honeydo's to do...
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you are supposed to do the honey do's when you can't fly. DOC Holliday LL~ LL~ LL~
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Tell my wife, John...on second thought, let's not rock the boat.
Still haven't got out. Thought I would yesterday but the weather didn't cooperate, windy and cold and damp. High was 53 I think. And here it is nearly June! Maybe Saturday if it warms up and stays calm.
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FINALLY--FLIGHT REPORT!!!
Got the Droopy Diamond out today...must say, it exceeded my expectations. VERY stable, to the point I was concerned at takeoff, when it settled into a very deep groove, it must be noseheavy and unmaneuverable--but not so, turns extremely well and tight. That extreme stability enables really nice square corners, no overshooting, coming out of a wingover just square and back into that deep level groove. Makes even MY corners look good.
I used 48' lines, and will try 52' next time as it is too fast--under 3.5-sec. laps, on 48' lines that's over 60 mph. This is a big plane I thought, 34" span, 240 sq. in. wing, but I guess that droopy airfoil lends itself to lotsa speed. It's probably 10 mph faster than my LittleAxe--I flew them back-to-back for comparison. The LA still flies very well but I think I'm gonna prefer the Droopy Diamond stunter once I get the speed under control. (I'm using a 6x2 prop now, can't get lower pitch than that!) I may switch out the .061 for an .049 just to see how it works with the smaller engine.
All in all, I count it a huge success. couldn't be more pleased with it. Thanks for the innovative airfoil Mr. Crocker!
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Sounds great. DOC Holliday