Small-Field Flying
Paul Bradley
32238 Spinnaker Run, Magnolia TX 77354; E-mail: [email protected]
PLANTING SEEDS:
Depending on how long you have been part of the great model-aviation hobby, you might have had a discussion about how to introduce others to this affliction of ours. That subject is appropriate from time to time. Helping others gain an interest in model flying is important if we want to keep the hobby going long into the future. It is also a great way to generate new flying buddies.
At the heart of most getting-started discussions is the question of how to capture the younger members of our society. Many different programs and efforts have been organized through the years with varying results. Because getting youth involved is such an important part of any endeavor, this month I'm going to highlight two current approaches to introducing youth to model aviation.
The first description comes from Arnold Christensen. He heads a model-aviation program for the Boys and Girls Club of Saint Lucie County, Florida. This is a great illustration of what can be done at the local level when you have an inspired leader and the support from a community organization. He wrote:
"This group of smiling faces show how enthusiastically the children in the Boys and Girls Club of St. Lucie County, Florida have responded to building and flying model airplanes. Actually they are but a fraction of the over 1,000 children in grades K–12 who meet after school in eleven schools and three clubhouses.
"In each approximate hour-long session, commanders are appointed who in turn select their captains in their Eagle and Hawk squadrons. The first order of business is the folding of a classical glider from the colored construction paper they choose.
"Then, demonstrations, which they all participate in, reveal that 'air,' although invisible, keeps the airplane flying. They blow at Ping-Pong balls glued to a string and watch them swing away. They vie with each other to see who has the strongest blowing power.
"Then it's asked: 'What also is invisible?' Hands shoot up in the air: 'Gravity?' 'Yes, that's what brings the airplane back down to earth.' Each one stands on the chair placed facing the others, and with a softball and golf ball in either hand at the count of three: 'One, Two, Three!' they drop both balls.
"They then rush outside to fly their new creations. 'Look, look! Mine's looping; mine goes farther than yours!' Paper gliders like a swarm of locusts fill the sky.
"From these paper classic gliders, the program moves to the next session where balsa wood catapult gliders are cut, sanded and glued. Then, as the boys and girls advance, the Delta Dart rubber-powered plane is constructed, flown and contests held. Eventually, each boy and girl gets the chance, with assistance, to fly a schoolyard RC flyer.
"These Eagles and Hawks, through their hands-on construction of model airplanes, not only enjoy flying them, but also find out that learning can be fun."
That program sounds great. The kids even end up flying a small-field radio-control model. It can't get much better than that!
The second program is on a national level and is part of the middle- and high-school Science Olympiad, which is an annual fun-based science-oriented competition. It includes an event called the Wright Stuff. In this year of celebrating the Wright brothers' accomplishments, the Wright Stuff event is most appropriate. For this program, the participants build rubber-powered indoor free-flight models to a set of specific parameters. The models are flown by teams of two, and the team with the high time wins the competition. It is a great way to start the process of getting youth interested in aviation in general and model aviation specifically.
I have been an event director for the Wright Stuff competition in my area, and it is satisfying to see the students giving their all. Because of the relatively large number of participants nationwide each year, I have to assume that some will become part of our hobby.
For that reason, if you have the opportunity to get involved in any capacity with local Science Olympiad students participating in the Wright Stuff event, please consider contributing some of your time. The seeds you help sow may become the next "big names" in model aviation.
This is the year for celebrating pioneer aviation. The Wright brothers helped piece together the puzzle for achieving heavier-than-air manned flight. Glenn Curtiss was another significant contributor to the early days of flight; he gave us the aileron and other early refinements of the Wrights' creation.
You may remember that last year I shared with you Pat Tritle's development effort for the DARE Wright Flyer kit. Pat lives in the Albuquerque, New Mexico, area and has available to him an original 1914 Ingram Foster pioneer aircraft. It is basically a clone of the Curtiss pusher, and it is on display at the Albuquerque International Sunport (airport).
The Ingram Foster is the inspiration behind another of Pat's great small-field-flyer designs. The photos don't do this excellent model justice. As with the Wright Flyer, I thought you would like to read about Pat's development of the 1914 aircraft.
"The specs for the model go as follows: span—43.75 inches (54.6 inches including the ailerons), area—621 square inches (less ailerons), length—43.125 inches, flying weight—25.3 ounces, wing loading—5.85 oz./ft², power—6V Speed 400 with 4:1 gear reduction, 11 x 7 APC Slow Fly prop, 20A ESC (Electronic Speed Control) with BEC (Battery Eliminator Circuit) and seven 800 mAh cells.
"Guidance is provided by one servo each for the rudder and ailerons and one servo for each elevator, and a JR R-600 receiver with the case removed.
"With three-view drawings obtained from the Albuquerque Aviation Dept. and 52 photos taken of the full-scale airplane in hand, I went to work. Scaling was done based on a beautiful set of 2.75-inch-diameter spoke wheels I got from Keith 'Sparky' Sparks.
"That sized the model to 1:7.25 scale, which put the scale prop length at 11 inches, which is the prop size for the 4:1 Speed 400 drive I had planned to use from the start. The overall scale outline is right on the money, but I didn't use the scale airfoil. The airfoil used is still undercambered, but isn't the constant thickness like the full scale.
"Framing the flying surfaces is completely conventional. The fuselage was a little different from the norm, but certainly not complicated. The model was covered with silk and dope, as I really wanted to duplicate the natural linen look of the full scale, and that's the only way I have found to really get it done. The silk was preshrunk to eliminate a lot of airframe distortion caused by excessive shrinkage.
"Rib tapes were added using silkspan, and the nail heads were done using a mixture of white glue and brown water-base paint. Then, the silk was sealed with three coats of 30-year-old nitrate dope which has yellowed to a deep amber color. Then, it was given a rubdown using two shades of brown pastel chalk to give it the aged look. The finished effect was just what I was looking for.
"A scale six-cylinder Roberts two-stroke engine and gas tank were fabricated from white foam, rolled paper, plastic tubes and anything else that looked like it might work. Since then, Sparky has produced a beautiful vacuum-formed engine that only weighs an ounce.
"The control hookups are all done with pull-pull cables. A series of pulleys were used to route the cables around the struts and away from the prop arc. The elevator controls are cabled up in scale location with the servo driving the idler cable from the top wing. The lower cable runs through the seat frame causing it to move side to side with control input.
"The first time the Curtiss flew the CG (center of gravity) was way too far forward resulting in a very heavy elevator feel and the need for full power to climb or even maintain altitude. So, I moved it from 32% back to 35% by relocating the battery, then added two alligator clips at the front fuselage 'V' brace, just to be on the safe side. Through a series of four test flights I found the optimum CG to be at 34%. At that point, the model flies very well overall.
"The rudder and elevator inputs feel pretty normal, but the ailerons are predictably 'heavy' and ineffective. To turn I find if you lead with the rudder and follow with a small amount of aileron it works well, then to recover the turn, use equal amounts of rudder and aileron together.
"It will cruise nicely at around three-quarters power, but to climb it needs all the power available. The model is not underpowered by any means, but there's so much drag that it takes a good bit of power to gain the little bit of added speed to go up.
"Landing is really the fun part. The approach is done at about half power with the nose down just a little. Then, at about a foot or two above the ground, just bring the nose up a bit and she'll settle right in. Surprisingly, the ailerons are adequate to keep the wings level on approach with little help from the rudder required.
"What's interesting, but again not a big surprise, is the model's very narrow speed envelope. Basically, it takes off, flies, and lands all at about the same speed. To climb, you need more power; to land you need a little less; and flying falls somewhere in between. Overall, the model really flies well, and is truly fun to fly. But like its full-scale counterpart, it's only happy in light breezes.
"Having flown models of the 1903 and 1909 Wright Flyers and the Curtiss Pusher, I can see a remarkable similarity between the two designs, but at the same time the airplanes are very different. The Wrights are more stable in roll while needing close attention to pitch, whereas the Curtiss is a bit less stable laterally, but has a very conventional feel in pitch.
"The main ingredient in both designs is the incredible amount of drag produced by all those struts and wires and other assorted paraphernalia hanging out in the airstream. Either way, considering they are all pre-1910 designs, neither fly a bit less than great!"
Before I close this installment of "Small-Field Flying," I want to share with you an instance of taking a published design to a new dimension—literally. The design is Rob Wesch's Micro Stuka that was featured in the March 2002 RC MicroFlight. As presented, it is a profile fun-scale model.
Using those plans, Zoran Posarac of the Vancouver, Canada, area built a great-looking full-fuselage version of the model. The picture was sent in by Zoran's friend Gerard Axionsci, who somehow talked Zoran into selling it to him.
The model uses a Speed 280 motor geared 2.8:1 with an 8 x 6 propeller, seven 300 mAh Ni-Cd cells, and it has a flying weight of 11 ounces. The wing is removable, battery charging/exchange is done through the canopy, and the model is covered with Litespan. The airplane is reported to be a great flier. Nice work, Zoran.
We are at the end once again. Please keep those great small-field model projects coming. MA
Transcribed from original scans by AI. Minor OCR errors may remain.
