Single Line Swept Forward Wing Glider Kites

Started by Doug Stout, Sep 05, 2019, 03:19 pm

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Doug Stout

Sep 05, 2019, 03:19 pm Last Edit: Sep 06, 2019, 12:35 pm by Doug Stout
For those of you who are new to single line glider kites, this has been a passion of mine since 2010.  My development and experimentation for this type of glider kite, and associated feedback, were contained in a discussion thread that spanned for almost 5 years on the former GWTW forum.  Steve Hall provided a great service to our kiting community, allowing us to have an online place for us to share ideas and exchange information.  It is great to see that Steve has an active roll on this new forum developed by Ken.  Thank you Ken and Steve.

On to the subject of this post, the Bird of Prey was my first generation, the Viper was my second generation and the Raptor is the third generation of this design concept.  The outline for three glider kites look very similar, but there are discrete differences, such as leading edge sweep and the associated length of the center to obtain desired performance characteristics.  When the former GWTW Forum closed, I was exploring larger sizes of my Raptor single line swept forward wing glider kite, where I use an ultra-light version with a 36-inch wing span for indoor competition over the past two years.  The versions of my Raptor with 48 and 74-inch wing spans fly better than expected and were used for my two show routines at the 2019 Wildwood International Kite festival.  The following is a picture of these two larger versions of my Raptor, where the fabric is PC31 (aka Icarex).  The color pattern layout is my version of the Air Force Thunderbirds.

Raptor 74F and Raptor 48F

I have a version designed of this kite with a 62 inch wing span that I hope to have built within the next few months.

Currently building a Raptor 48F for a fellow kite flyer, who lives in upstate New York.  The following is a picture of it under construction, where the 24 panels have been glued and sewn together, and the edge has been hemmed.  Next step is to add the wing spar sleeves, reinforcements, batten pockets and the white striping to outline the simulated cockpit.

Raptor 48F Under Construction

For those of you who followed my thread on the former GWTW Forum, I have a Google Drive that contains my kite plans, pictures and other technical information.  The following provides access to my Google Drive.  As I complete the evaluation of a design concept and satisfied with the performance, I add the plans to this drive.  In the near future, I will add the plans for the Raptor 48F.

Doug Stout's Kite Google Drive

If there is interest, I will add my future development activities to this topic.

Yours in kiting,

Doug
"We never really grow up, we only learn how to act in public."

Michael Davis

Those are so cool. I was fascinated with the X-29 project prior to joining the Air Force in '85. I think they might have been using it in recruiting posters at the time. Ended up working on a plane that would probably make a good glider, the A-10.
My first name is Trenton, but you can call me Michael

Doug Stout

Sep 05, 2019, 10:41 pm #2 Last Edit: Sep 06, 2019, 12:35 pm by Doug Stout
Michael,

Thank you for your kind words.  The X-29 was the inspiration behind me trying swept forward wings.  As with the X-29, the swept forward wings did eliminate the tip stall issues we have with swept back wings, especially ones with narrow wing tips.  This type of wing platform also eliminates the need to have washout for stability at the center of each wing panel in the form of loose fabric, which washout reduces the efficiency of the wing during the glide.  You will notice that I use wider wing tips than conventional swept back wing kites, which wing tips are under tension by a curved batten at each wing tip.  This allows the wing tips to washout under load and during tight turns, which provides additional stability.  During the glide, the wing tips are in line with the rest of each wing panel.  The typical location for the wing spars along the leading edge that we use in our kites eliminated the concern with aeroelastic divergence that occurs in full size aircraft with the wing spars located at the high point of the airfoil, where higher angles of attack would twist the wings around the wing spars and upward along each leading edge.

The X-29 had a negative static margin of up to -35 percent and needed three computers to assist the pilot to keep it in the air.  Unlike the X-29, the static margin for my single lifting surface swept forward wing glider kites is much closer to the calculated neutral point.  As a point of reference, the static margins for the Raptor 48F and 74F are -3.1 and -2.4 percent, respectively.  The 2nd prototype of the X-29 was used to explore very high angles of attack, and was maneuverable up to an angle of attack of about 25 degrees with a maximum angle of 67 degrees reached in a momentary pitch-up maneuver.  I have experienced high angles of attached with the various sizes of my swept forward wing glider kites, with excellent stability and no signs of stalling at the wing tips.

For indoor single line competition, I use my Raptor 36M that has a wing span of 36-inches, weighs only 8.2 grams, with a static margin of -1.9 percent.  The following is a picture of this size Raptor, where the fabric is Dyneema Composite Fabric of different densities to assist in obtaining the desired balance point and providing stiffness to the wing along the leading edge near the center/nose of the kite.

Raptor 36Ms

I'm a firm believer in designing kites that are aerodynamically efficient, easy to fly and make me look good.  I am very fortunate that my 5 years of research and development have provide me with glider kites that are a joy to fly, which I have built for many others throughout the USA, Canada and the UK.

Based on your background and interest, the following two links provide my two articles for development of these glider kites, and bridle design and adjustment.  The third link provides the presentation I gave at the 2017 AKA Grand Nationals regarding glider kite aerodynamics and tuning techniques.

Development of Swept Forward Wing Single Line Glider Kites Article

Kite Bridle Design and Adjustment Article

Glider Kite Aerodynamics and Tuning Techniques Presentation

If you should have any other questions, please feel free to send me a note.

Yours in kiting,

Doug
"We never really grow up, we only learn how to act in public."

Lex Bijlhout

Ahhh,  so good to have this thread back and alive.
Thanks for keeping us posted Doug!
Remember the Titanic was built by professionals
The ark by amateurs.

Mike H mikenchico

So glad you've joined "Kite Gnome" so we can continue to follow your explorations. And thank you for saving, linking, and freely sharing your previous threads and plans so we can all follow from the beginning.
"You do not quit playing because you grow old; you grow old because you quit playing." - Oliver Wendell Holmes (modified)

Doug Stout

Raptor 48F finished and on its way to a kite flyer in upstate New York.  The back lighting did interesting things on a few of the panels, such as the charcoal simulated cockpit.



Yours in kiting,

Doug
"We never really grow up, we only learn how to act in public."

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