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Old Nov 19, 2007, 01:32 PM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
1,495 Posts
Yippee!
KFerret (ferret) DLG – (Pics & Plan added!) new design and maiden report

Finally found enough time to put together a plane that melds a couple things I have become rather fond of and something I have always wanted to try– the Kfv airfoil, flying wings and DLGs.
I had built a free-flight model some time ago (pic below) that proved that the concept should work. It is a DLG based on the Boomer-EX, Red Herring and Weasel format – delta wing. This version is rather small, hence the wingloading is higher that it should be (3.5oz/sqft rather than high 2’s) in practice.
It shouldn’t take more than 2-3 hrs to go from foam to flight. The main structure is single skinned FFF with starbuck’s stirring sticks for strengtheners. I am not sure if all starbuck’s carry these, but they are blades of thin light wood with rounded edges. They are 7” long, ¼” wide and about 1/32” thick – light and strong. They are used for the dihedral brace (2-3 degreees) and stiffeners around the servo cutouts. The servos are in holes that are cut all the way through the wing allowing them to be mounted flush.
The tail is meat-tray foam and a bamboo skewer. Small pieces of leftover skewer are used in the nose to give the battery and Rx something to be tied down to.

Almost forgot the KFm specs. The wing has a top step that is 50% at the root and tapers to 40% at the tips. Why the taper? I figured it would help against tip-stall. The leading edge is formed by folding over the foam and there is nothing between the top and bottom step, so its only 2 FFF layers thick.

Maiden Report –
Just got back from my lunch break where I took it out for its maiden. The weather man said 5-10mph winds today, but when I got to the park, it was more like 10-15. I wouldn’t usually maiden under such conditions, but what the heck (I only have 3 hrs invested). First couple of flights, showed it to be slightly tail-heavy (waaay too twitchy). A dab of clay on the nose and things calmed way down. Once I got the CG and my launch pre-set set pretty close to perfect, I was able to get 60’ to 70’ launches and 30+ second airtimes. Keep in mind that I have not made any attempt yet at cleaning up the structure for drag yet (batter, Rx and wires are in the breeze). With a bit of a hollowed foam fuse and burying the servo leads, higher launches and longer flight times are sure to come.
It handled the wind with ease. Not a hint of tipstall no matter what I tried and rolls were very axial. Circles were solid with no counter control necessary. Some lift was encountered but the high wind did not allow me to really stay with it. I am now dying for a day with lower wind more coherent lift to really wring her out. Overall, she is exactly what I was hoping for.

I will post the pics I took in the morning.

Specs:
Span: 24”
Root chord: 9.5”
Tip chord: 4.5”
MAC: 7”
Dihedral: ~1/4” under each tip
Area: 168sqin.
AR: 3.43
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Last edited by wingnutt; Nov 20, 2007 at 12:46 PM. Reason: text - KFm specs
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Old Nov 19, 2007, 02:10 PM
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minifly's Avatar
Cape Town, South Africa
Joined Jan 2003
2,060 Posts
Cool! I wonder how it would work for slope...it's windy most of the time here.
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Old Nov 19, 2007, 02:14 PM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
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Slope should be awsome, but havent tried it yet. sholdnt take more than a small hill or building to have a great time. it will turn on a dime and hit you on the back of the head if you're not careful (ask me how i know ). Just be sure to ballast it down a bit for heavier winds. Great for a light slope day though.
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Old Nov 19, 2007, 03:57 PM
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Joined Jan 2005
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Did you use a launch peg or just grip it and rip it?
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Old Nov 19, 2007, 05:15 PM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
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grip it and rip it. hey i like that! there isnt a peg or thumb pad. simple, fast, cheap and fun! my first DLG and loving every toss.
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Old Nov 19, 2007, 08:47 PM
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It's about time someone came up with a easy to build DLG. Great job wingnutt.
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Old Nov 19, 2007, 10:20 PM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
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bf - its not all my idea, the Revert was a big inspiration. like I said, ill post some pics and plans tomorrow morning after the wind gods wake up
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Old Nov 20, 2007, 01:17 AM
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kimhey's Avatar
nøtterøy, NORWAY
Joined Mar 2006
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I will give this one a try! It is first on my build list now....
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Old Nov 20, 2007, 01:28 AM
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Skycruiser's Avatar
Fairlie, New Zealand
Joined Nov 2006
2,866 Posts
Looks good wingnutt. 30s while still dirty must put it in Alula class cleaned up. Why oh why can't we get fff down here?

Nick
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Old Nov 20, 2007, 05:05 AM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
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pics moved to first post

pics moved to first post.
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Last edited by wingnutt; Nov 20, 2007 at 08:23 AM. Reason: pics moved to first post
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Old Nov 20, 2007, 07:38 AM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Very nice 'nutt.

I've kinda been interested in DLG, just for grins... Maybe slope off the face of a corn feild or something around here

You may have put me over the edge!
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Old Nov 20, 2007, 08:26 AM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
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gb - DLG is fun, but be sure to stretch a bit first. dont need a full piroette, a half turn is all i tried so far and works well. i felt the winds were too high for a full blown launch. doesnt need much to slope from either. had it twising and turning on a canal bank this morning.
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Old Nov 20, 2007, 10:54 AM
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kimhey's Avatar
nøtterøy, NORWAY
Joined Mar 2006
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And how many inches/cm from the nose is the Center of Gravity?

Starting soon.... just have to decide whether to use Depron(foam) or EPP..
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Old Nov 20, 2007, 11:21 AM
we spozed ta be tite!
fr0g_D's Avatar
Nowata, OK
Joined Aug 2005
159 Posts
Very Kewl! Man I have been wanting to try a DLG.
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Old Nov 20, 2007, 12:31 PM
Will work for foam
wingnutt's Avatar
United States, WI, Muskego
Joined Apr 2005
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kimhey - the starting CG is about 3.75" (9.5cm) from the nose. the elevons are 1.25" (3.175cm) all the way across.

frOg D - thanks for the kind words. This is my first DLG and really like it (especially while my Lipos are charging). great excercise too. just keep the Rx batt small, this one is using a 110mAh batt.
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