ECIM Vice President Rob Romash provided the following report on the free flight activity on Saturday September 6:

Tom Iacobellis and I couldn’t hit the epic Labor Day free flight weekend so we had to settle on the following one.  Kudos go to Horace as neither of us could get a base pass the day before and we dutifully followed him on base.  After flying in the hangar for nearly 30 years now I am pretty sure this was the hottest and most humid day I have ever spent there.  Much of the day was spent moving around making sure sweat drips didn’t hit the models during preparation.  Opposite to the salt mines during the World Championships in Romania where we moved to stay warm, this day we had to move to evaporate moisture so you could bear it.

Tom showed up with one of last year’s F1D models and vowed to “stick it” in the roof.  He wound the living snot out of it several times but an extreme wing warp kept the model from really climbing out, he also had the model doing some nice 360 degree rolls on takeoff, very entertaining.  Tom also brought along his ornithopter and that model did much better, he got the RPM’s down on the wing and made a flight of around 5 minutes before a structural failure boxed the model.

I showed up with my new F1L, we sort of knew.  After a disappointing showing at the Kibbe Dome in Idaho with an attitude of “My old F1L still has some stuff left” it didn’t.  I built this new model with a clear hope to improve and from what I see it is doing pretty good at least for “Romash”.  I brought my simple equipment package and forgot my notes from a few weeks ago when I flew the model here.  The first real wind I thought “What was that back off?” seems it was more then I planned to use and the model slowly cruised its way up just touching the ceiling beams right at the top, second hit it dropped itself right on top of the of the beam.  Good thing it was within easy reach of the center catwalk and we had a 22 foot club pole.  Not so good was that the temperature at the top was near the surface of Venus.  After a successful retrieve and the loss of about 8 pounds of fluids I came back down.

Over the day Tom had a high time of around 20 minutes on his F1D ( I think ) and a bit over 5 on his ornithopter.  I managed to get some good results for me with several flights over 18 minutes with a high times of 19.56 on my F1L.  All in all any day in the hangar is a good day.

I spent some time observing the FF activity Labor Day weekend and since I am not directly involved in indoor free flight I asked a few questions:

Question 1 - Covering Material:

Years ago the most commonly used covering material was micro film.  Micro film was made by filling a rectangular container with water and pouring lacquer on its surface.  A wire frame was then lifted from underneath to pull the floating lacquer film up and securing it onto the airframe.  The thickness of the microfilm is 0.25 Microns.  Today, the most common covering material is manufactured by just one company in large rolls and costs $10,000.00 per roll.  Fortunately there is an entrepreneur who buys a roll and then resells the material in smaller quantities.  The material is primarily used as a separator in the manufacture of capacitors and has a thickness of 0.5 Microns.  The film is transparent and is used that way by some competitors.  Other competitors crumple the film and this produces in a film that looks cloudy and appears more visible.  It is interesting to note that this material is used by modelers in other countries as well.

Question 2 – Propellers

There are many Free Flight categories; some propellers use balsawood blades and others use built up frame construction covered with the same film used for the flying surfaces.  The balsawood blades are made from balsawood sheets shaved/sanded down to .005 to .015 thousands of an inch in thickness.  The built up blades have frames consisting of very thin balsawood sticks or carbon rod .009 to .015 inches in diameter.  Each propeller can take several hours to build.  On some models variable pitch propellers are used.  The propeller hub is designed to have maximum pitch on a fully wound motor and slowly decrease as the motor winds down.  On the larger models the propeller speed ranges from 30 to 120 RPM.  On the smaller models the propeller speed ranges from 100 to 300 RPM.

Question 3 – Rubber Motors

The rubber used for these models is manufactured by the Good Year Company and is used by Free Flight competitors throughout the world.  “ArmorAll” or similar liquid is used as a lubricant to keep the rubber strands from sticking to each other.  To test and/or estimate the number of winds needed to get to a certain height, fractional motors use balsawood sticks of varying lengths in place of the rubber.  A half motor would use half rubber and half balsawood stick.  If the model reaches a height of 90 feet with a half motor then a full motor could reach 180 feet which is the maximum in Hangar 1.

Question 4 – Airframes

Wings and tail feathers are primarily constructed using balsawood frames covered with film.  Every competition category has prescribed dimension and weight limits.  Some fuselages are made from solid balsawood and others are rolled tubes of balsawood shaved/sanded down to .005 to .015 inches in thickness.  Some models use a boron filament so thin that it is invisible to the naked eye.  The filament is tied to the top of the fuselage at the nose and rubber motor end and placed over a post in the middle.  The idea is to control the warping of the fuselage due to the tension of the rubber motor which can affect the motor’s thrust line.  The airframes and some propellers are so fragile that if you walk passed them quickly you can damage same.  Words of caution – walk don’t run.

Question 5 – Adhesives

To minimize the addition of weight to the model a very common adhesive is Ambroid cement thinned with lacquer thinner.  The second most used adhesive is cyanoacrylate (CA).

Question 6 – Model Steering

Indoor Free Flight models are at the mercy of air currents within a building.  To prevent a model from colliding with the walls or ceiling a balloon filled with Helium tied to a thin fishing line is used to steer the model.  The balloons are 2 to 3 feet in diameter and provide enough lift for a thin fishing line.  3/8 inch diameter foam caulking covers the top twenty feet of fishing line.  The caulking is soft and prevents the thin fishing line from damaging the model and is more visible.  To steer the model the line (caulking) is positioned in front of the model’s wing and when the wing touches the line it induces a turn.  If the model gets into a position where damage may result the line is positioned next to the propeller to stop same and the model will slowly and safely descend along the line.

If you have not taken the time to watch the Free light activity in Hangar 1 you are missing out on a great experience.  I marvel at the patience these true modelers exhibit.  They are world class competitors using the latest technologies and have brought back the World Championship FAI Gold, Silver and Bronze medals several times.