Kling tgwrew kong

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Wing http://web.archive.org/web/20050213191156/http://pr.erau.edu/~all...

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Modified Klingberg

While co-oping at NASA DFRC I learned about the Horten brothers andspecifically the improved handeling qualities of thier pure flying wing designs.They accomplished this with a combination of high aspect ratio, high taper ratio, and a non-linear wing twist. Using a vortex-lattus code, Al Bowers predicted thatmost of the time the Horten Xc would not have adverse yaw, and in fact wouldhave proverse yaw at most lift coefficients. Adverse yaw is a tendency of theaircraft to yaw the wrong direction with a roll input(ie. turns left when you rollright). Since the Klingberg Wing has similar taper and aspect ratio, I decided tobuild my Klingberg with the same wing twist as the Horten Xc.

The wing is a pleasure to fly! Video shows that it has no adverse yaw. To obtainthe new twist, I replaced the stand-up jig with a new one that gives a sin^3 wingtwist. The heights of the rib stations are:

root 2.90in rib#8 2.40rib#2 2.93 rib#9 2.09rib#3 2.97 rib#10 1.67rib#4 2.96 rib#11 1.20rib#5 2.91 rib#12 0.69rib#6 2.80 rib#13 0.20rib#7 2.63

Here is what the jig looks like


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This jig determines the twist of the wing. It also causes the leading edge to benddown at the tip. This gives a negative dihedral effect. To correct for this Iincluded a dihedral angle at the joint of the two wing halves of 4.5degrees.

I also changed the size and shape of the elevons so that the change in lift thatthey produce would have the most positive effect on yaw. The combination of

twist and sweep causes an induced angle of attack on the outboard sections. Thiscauses the lift vector to be inclined foward. The down moving aileron causes anincrease in lift, thus an increased upward force AND an increased foward force. Iused a study of different elevon configurations for a flying wing of similar twist, aspect ratio and taper to determine my elevon size and shape. My elevon includesall of the tip block and has one less rib, the hinge line was also changed to beparrallel to the trailing edge. The elevons have a width of 2.5 inches.

bottom view

My elevon hinge lines did not come out straight because of the new twist but thisis not a problem. Monocote hinges have worked well for me with a full lengthstrip on the top and tabs of covering on the bottom at the ends. Seal the edges of the top strip with the elevon in the down position and seal the center of the topstrip and the bottom tabs with the elevon in the up position. After that don'ttouch the hinge with the iron agian or the gap will shrink! The hinge gap due tothe curved hinge line is small and doesn't look bad.

The new twist makes the balsa wing sheeting much harder to put on. You willneed alot of pins. Do not use cardboard for the wing jig! I used sign board madeof foam and paper and it was almost to soft to use. Also, you must spray the

balsa with window cleaner multiple times to soften it.My initial flights in Lancaster were successful thanks to excellent weatherforcasting of Casey Donahue, the greatest weatherman that ever lived and friendof Captain Solo. I recently made some flights in the snow to determine the aft cglimit (snow makes a soft crash). Currently, performance seems to be less than aconventional 2-meter glider but I expect this will get better when the correct cg isfound. One of these days, I will measure the L/D of my Klingberg and the


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conventional glider for comparison. I plan to do this by shooting a landing froma height of 20ft onto a field on a calm day and measuring the distance they go tofind the glide slope.

Tell me what you think

If you would like to read more of the theory behind the twist, click on theNurflugel link and go to Nurflugel Papers Section, then "A Retrospective: FlyingWing Design Issues"

Other LinksNurflugel

Chris Good's computer controlled N9MBasic Design of Flying Wing ModelsAndy McDonald's Flying Wing Page

Power Scale Soaring Model of Horten IXTons of RC Flying Wing Pictures

Huib's Aviation Books and Flying Wings PageAla Voladora flight moviesThe.Wing.Is.The.Thing

Video of electric wing made from 747 partsMy Homepage

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Kling tgwrew kong