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Another Thermal Soaring How-To Tutorial

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**Use the coupon code  glide10off at check out and save 10% off your order of DVDs or Digital downloads. Code does NOT apply to the new Thermal Soaring Master Class.

Here is a recent flight with my Xplorer 3 F5J with some instructional narration with an onboard camera angle that shows the wing trailing edge working while in flight. This text expands a bit on what the narration describes and perhaps you can pick some tips that you can apply to your thermal soaring set ups.

What I was looking for in this video test flight was the differential settings and how they worked. On the ground the settings looked OK and the basic roll of the plane was sound with any adverse yaw canceled out. Setting the differentials of the inboard flaps is a bit more tricky, and you always want to have a minimal amount of diff. ratio and only enough aileron following to get the roll rate you want; I always want a fast roll rate especially at low speeds.

The video clearly shows that the flap differential ratio was wrong, I was getting to much UP rate and not enough down travel. In a roll correction, the right surface was going up a lot while the opposite surface was hardly moving. In thermal camber mode, you want to minimize differentials and roll so the wing stays cambered more of the time. You should reduce the flap differential rates and the aileron following/mixing as much as possible.

At slower speeds the wing needs the inboard flaps to keep the roll rate, but any differential travel offset will not be very effective in reducing adverse yaw due to the low air speeds and the inboard location of the flaps. At low speeds the rudder should be doing most of the adverse yaw correction. The ailerons shouldn't be deflecting much in thermal camber mode anyway, so any aileron differential set won't have much effect unless there is a large surface deflection. Your wing set up has to work efficiently when flying slowly with camber and with a minimal amount of roll deflection.

As I mention in the video, last month I had a bad flap servo wire that could not be fixed at the field, but it was a good day and I'm lazy, so I disconnected both flaps, taped them shut, and flew just RDR/ELV/AIL. No camber changing, no snap flap, no flaps mixed for roll. After some retrimming, the Xplorer flew great, very smooth as the roll was reduced, but it thermaled great at a slightly faster speed without additional camber. It flew so well that I now fly this plane more often in cruise camber (which is still some camber) and try to keep the basic thermaling speed a bit higher than I did before.

Lesson: Change things up in your radio set up to give yourself some perspective. We get locked into settings that may not be right for the glider, but your mind has long since adapted to flying with these settings. Drop your differentials down one flight, reduce your rudder mix another, increase your aileron throw. Change your CG back. See what happens. Give new settings a chance before changing back. Only those pilots who risk change learn and grow their skills.

I have a big motor currently installed on the Xplorer for summer, way too much fun in stronger lift conditions, but at a big penalty. That penalty is a ton of tail weight to offset the Neu 1110 motor and required 2200 pack. I initially used my F3J rudder settings for the E-fuse, but soon discovered that with the tail weight, the fuse would go through a number of un-dampended yaw excursions anytime the rudder was deflected past 10 degrees or so. Any mass in motion wants to stay in motion, that big tail weight chunk out on that long boom once moved, did not want to stop moving, making smooth yaw control and coordinated turns just about impossible.

To help correct the yaw issue, I increased the rudder servo resolution by going even further inside on the servo arm (MKS 6100 HV) and then decreased the total servo throw a bit. Also added a small amount of expo to dampen the initial throw a bit. I also reduced the ail/rdr mixes in each flight mode. These changes reduced the activity and angle of the rudder, which is huge on the Xplorer, and the yaw excursions all but went away.

The rudder was now easing into its angle smoothing the yaw response, instead of an abrupt angle change causing a fast yaw force which got that tail weight moving too quickly. Turns actually got better, and I have very little aileron diff. in any flight mode. I can always feel that weight out there, but now the plane tracks straighter and holds heading in a turn. Lesson I learned is that my initial program set up was 'over ruddered' so I've done the same rudder changes to my F3J fuse and program.

To learn how I built and prepped this Xplorer, get the F3X Building Clinic, and to learn how I built the F5J electric fuse and optimized the two power systems I used, get the Electric Sailplane Clinic 3, links below.

**Use the coupon code glide10off at check out and save 10% off your order of DVDs or Digital downloads. Code does NOT apply to the new Thermal Soaring Master Class

Click Here Order the Thermal Soaring Master Class

Click Here Order the F3X Building Clinic

Click Here Order the Electric Sailplane Clinic 3

I'm happy to answer question or give advice. Mail me here:

Paul Naton - Radio Carbon Art



 

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