Friday, October 16, 2015

Efficiency and Model Aviation - II

In February of 2015 I had written a blog post entitled “Efficiency and Model Aviation”; the article placed emphasis more on simpler rubber powered free flight although it did mention the super-efficient F1D indoor free flight competition models. As the comfortable outdoor flying season is winding down where I live I am thinking about some of what I learned about model airplane efficiency. Much of this is related the radio control glider flying I do but I am now thinking about more efficient outdoor free flight models also.

My Allegro Lite RC Sailplane Efficient but Not Compared to Larger Sailplanes

Recently I watched a NOVA program entitled “Making Stuff Faster”; it can be watched online at this link . Of particular interest to me in this program was the Oracle sailboat which is capable of top speeds over 50 mph and the Velox 3 bicycle that set a world record of 83.1 mph.  New technologies made possible by new lightweight materials made the high-speeds obtained possible.

Foam Super Scooter Not Real Efficient

Fiberglass Shadow More Efficient

Radio Control sailplanes I fly stay aloft because of lift from deflected air created by the wind blowing against a slope or from rising thermal air currents.  For the slope flying I have been moving away from gliders made mainly from foam to gliders that are more rigid built from fiberglass and other rigid materials. Flying from the same slope with the same conditions on a particular day the difference in performance is amazing.  At times the foam gliders will not stay airborne for more than 30 seconds while with the more efficient fiberglass gliders I can fly easily for several minutes. The reason for this goes back to my first article where Lift / Drag were discussed. 

Xplorer Sailplane Very Efficient

Circling in Thermal Lift

This summer I also flew in some thermal duration sailplane contests. Compared to other sailplane pilots my sailplanes did not perform very well. Much of this was piloting skill but still I was at a disadvantage flying smaller sailplanes in competition against sailplanes with twice the wingspan. There are aerodynamic factors of why these larger gliders are more efficient in using the available lift from thermal air currents than my smaller sailplanes.

Electric Starduster Climbs Steep 

Pearl E202 Construction

Electrical Components Texas Timers

Looking ahead for 2016 I plan to do more flying of larger, more efficient outdoor free flight models. A big factor in outdoor free flight competition is how high the model will climb before going into the glide. I am building the Pearl E202 E36 electric powered free flight but to test the electric components it will use, everything was installed in a larger glow powered airplane. The power system of brushless electric motor and a lithium battery that provides current at a very fast rate allow this plane to climb darn near vertical.  

Lidberg NJAPF P30 Model

Brought out from collecting dust in the basement recently is a rubber powered P30 competition class model. With old rubber strands for a motor, the climb rate was not too impressive on some trim flights. I have been given much advice on the strand make up of a rubber and how much to wind it. No doubt the airplane will give much longer flights in the future when flying more efficiently.  The previous summer I had experimented with a free flight discus launch glider. I went through phases of learning how to launch it without breaking, getting more consistent high launches, and then adjusting for a longer glide. Next year I plan to finish another glider as the first one flew away in a thermal air current.

Bill Kuhl

Vendors Mentioned

Texas Timers – electrical components for E36 free flight 

PearlFreeFlight  - E36 free flight kits  

AA Lidberg Plan Service – NJAPF P30 rubber power free flight kit 

Xplorer RC Sailplane 

Related Blog Articles

Efficiency and Model Aviation

Slope Soaring a Heavy 2-Meter Glider on a Small Slope

My Small Slope Soaring Webpage

Allegro Lite Finished and Flying

Watching the Super RC Sailplanes on Saturday

Unwinding With Free Flight Discus Glider

Free Flight Glider Discus Update

Tip Launched Glider Slow to Come Down

Goodbye to My First Tip Launched Free Flight Glider

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