Small-Field Flying - 2015/04
Francis and Gertrude Rogallo’s remarkable wing
I received a nice note and photo from modeler Christian Moes, of Canada, about his small-field/indoor aircraft. Like many aeromodelers these days, Christian used the power system and electronics commonly seen on popular small ready-to-fly models. Sporting an 18-inch wingspan and a flying weight of 38 grams, the aircraft is a terrific flier.
What we don’t often see on models of this size is the use of the Rogallo wing. This wing is a perfect match for small-field models and is probably the easiest to make for its relative lifting area. It is well suited for small model airplanes built for slower speeds, such as the Rogallo Rick that Christian built.
The Rogallo wing was developed in 1948 by NASA engineer Francis Rogallo and his wife, Gertrude. They were both kite hobbyists and used that background to develop what they called the Parawing, also known as the Flexible Kite. By the early 1960s the full-scale aviation community had adapted the Rogallo wing to sport gliding in the form of hang gliders.
The Rogallo wing has been used by the model aviation community throughout the years, but it is not often seen at small flying venues. Beyond its simplicity of construction, it offers plenty of lifting area for the span of the wing. Christian’s model has a wing area of 128 square inches — not bad for that wingspan. This larger area keeps the wing loading low for slow-flying models.
I don’t have the plans for Christian’s aircraft to share with you, but I can offer some guidance to help you develop your own Rogallo wing-based small-field flyer. There are a few simple parameters to follow when building a Rogallo wing model:
- The model’s center of gravity (CG) should be located halfway back along the keel and positioned below the keel by one-third of the keel length.
- The thrust line should pass through the CG.
You can make the fuselage and tail surfaces any shape that pleases you and move the equipment as needed to achieve the correct CG location. When that is done, go enjoy some nice Rogallo wing flying.
If you would like a larger version of the diagram, it is available for download from my website (see the Techniques and References section). Also available from the website are plans for a micro Rogallo wing model by my brother, Ralph, called the Cootie. It is great for calm-day or indoor flying. My website address is listed in the Sources.
Thanks for sharing Rogallo Rick with us, Christian. It is a nice reminder of how well suited the Rogallo wing is to small-field model aircraft.
Lo ’N Slo Revisited
Back in the February 2014 edition of this column, I shared a nice foam board model by Bill Welle called the Lo ’N Slo. This is a larger, slow-flying RC model that is well suited to our small-field venues.
Bill is an autogyro enthusiast and has developed a slick, strap-on autogyro conversion setup for his Lo ’N Slo model. You simply remove the wing that is held on with rubber bands and replace it with the autogyro setup. When in place, power up the model and you will enjoy the flying qualities of a twin-rotor autogyro.
The plans and full-size parts templates for the Lo ’N Slo can be obtained from my website in the downloadable plans section. I have also added the drawings and parts templates for the autogyro conversion kit.
Thanks, Bill, for sharing your nice small-field models with us.
When Curl Is a Good Thing
I always enjoy hearing from John Krouse, a regular contributor to this column. He is a modeler who sees opportunity where many of us might see problems. A case in point is the curve of Depron sheets, especially 1 mm Depron foam. It is rolled before it is cut into the sheets we buy. The thinner sheets of Depron are popular with indoor model builders and for some of our smaller outdoor models.
I have used the curve inherent in 1 mm Depron foam sheets to create camber in a small model wing, but John has used that curve to better advantage. He orients the curve in the sheets to create dihedral in his wings and stabilizers. Take a look at the photo he sent — a clever idea, John!
Wow, here I am at the end again. As always, please let me know what you are up to so I can share your great work with our small-field flying community.
Sources
- Paul Bradley
10201 Scarlet Oak Dr. Independence, KY 41051 [email protected] www.parmodels.com
- Depron foam
Transcribed from original scans by AI. Minor OCR errors may remain.
