Monday, June 22, 2015

Slope Soaring Heavy 2 Meter Glider on Small Slope

Adapting model airplanes and available flying sites I have available has been a challenge that I have been pursuing lately, particularly flying from small slopes with radio control gliders. I have been flying smaller lightweight gliders mainly because of less cost, available as a RTF, maneuver in small spaces, and in most crashes there is no damage.

Side View Shadow 2 Meter Glider

Several years ago I purchased a heavy 2 meter glider used that looked to be aerodynamically clean. The entire stabilizer pivoted with no external controls and the rudder horn was enclosed as well, only control horns and short pushrods were exposed for the ailerons and flaps.  My thought was to fly the glider from a big slope but when I finally installed radio gear I thermal soared the glider and found at times it climbed in thermals pretty well. Because of some battery issues it gained additional weight through repairs and it was already over 3 pounds. 

Super Scooter Foam Glider and Shadow

Last Friday evening there was a south wind forecasted at 9 mph. I thought this would be a good chance to try slope soaring the Shadow 2 meter from a relatively small slope.  The grass is really tall on the slope to cushion hard landings and there is plenty of open area with no obstacles to hit.  I launched the Shadow and it was flying but not very high.

Shadow Front View

After a couple of short flights to get the feel of the glider I made a couple of flights that were probably 5 minutes long. I had to keep in a pretty narrow lift zone and turn very smooth but it would stay up. I thought doing a comparison with the foam Super Scooter would be interesting. Repeatedly I launched the Super Scooter after the first turn on the slope the foam glider had landed on the slope. Switched back to the Shadow and it was again staying aloft.  Saturday I returned to this slope but was too late for the south wind and the Shadow would not stay up. Traveled to a larger slope for SW wind and had some flying with the Shadow but the wind was switching to almost west. 

Hand Launch Comparison

When I was first flying the Shadow 2 meter I had done a hand launch comparison with my Gentle Lady wood glider.  Consistently the Shadow glided much farther down the field. A hard concept for people including myself to comprehend is the L/D (lift over drag) is not related to weight. The heavier glider will just glide faster down the glide slope. One factor related to the L/D is the wing aspect ratio, the longer wing with narrow chord has less drag. No doubt a stiffer none-foam air frame makes for higher efficiency as well.

Bill Kuhl


My Small Slope Soaring Webpage

Comparing Two 2-Meter Gliders

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