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Written by Gordon Buckland
RC Soaring
As seen in the March 2020 issue of Model Aviation.

joe wurts
Joe Wurts created this third-vector diagram to help pilots understand the concept of pinpointing the direction of a nearby thermal.

WHY DO SO MANY PILOTS fail to max in Thermal Duration (TD) events when others find a way to stay up? I think I understand part of the answer, and the solutions are no longer secret!

We should all be better-skilled pilots today than in years past thanks to the amazing learning tools that we have, such as the "Paul Naton Thermal Soaring Masters" video series from Radio Carbon Art Productions that features Mike Smith. We’ve also had champions such as Joe Wurts and Daryl Perkins share their knowledge for a couple of decades. So why are pilots still sinking out too often?

It was apparent at the Tangerine Soaring Championships, held November 22-24, 2019, in Ocala, Florida, that many Thermal Soaring pilots could score better if they got into the habit of following some proven RC Soaring basics. Conditions were windy at times—particularly on Saturday as a cold front approached. The 10-plus-mph wind made conditions tricky, and the pilots needed to pay attention to the signs if they wanted to get their times.

During Saturday’s contest, a pilot asked, "How do you decide which way to go before you launch?" Let’s explore that subject because the decision is key to improving the longevity of any Soaring flight.

Pay Attention to These Before Launch

  • The previous group: You must watch the preceding flight group to see where they went and what was working for them. You will often observe regular cycles of lift traveling through and be able to predict the next thermal’s approach. During windy conditions, certain geographic areas work consistently well because of the moving air rising and falling over variations in the terrain. If you are not paying careful attention to the preceding flight groups, you might not observe this and could miss an easy ride when it’s your turn.
  • Birds: Signs, such as birds, are often missed because pilots are not paying attention. Not just birds turning in a thermal, but any birds. They all show the type of air in which they are flying. A traveling bird that is "straight lining" still shows lift and sink similar to what a model airplane does.

    Watching a buzzard tuck its wings to fly fast is a sign of sinking air and an area to avoid. Small, insect-eating martins and swallows linger in an area if there is lift that brings up insects from the ground. If you see them milling around, that’s where you should be.

    Despite this, other pilots launched and followed each other upwind to sink out when there was a bird that was crosswind and staying up in lift. The pilots did not fly to the bird because it was windy, and the bird was not in the upwind direction where that they were so focused on going to. (They found out that going upwind was sink.)

  • Opponents’ aircraft: Unless you are launching first in a man-on-man contest, you can watch the launch and the first minute or so of your opponents’ flights to see where they go they go, what air they fly through, and what lift they find. After you launch, pay attention to them or have your caller constantly report their progress. You need to have a strategy that allows you to reach the "pack" if they find better air than you, so don’t go too far away on your own.
  • Wind direction and varying strength: Pay constant attention to what the wind is doing, even when you are not flying. Be aware of the prevailing wind direction and strength because that is your only reference to understand changes. Any change in the direction is a valuable sign of what lift is nearby or has gone by. Any lasting change in wind speed reveals where and how far away the lift is.

The most obvious sign is a reduction in the prevailing wind speed. This often indicates that lift is approaching upwind. Increased speed can mean that lift has passed and is now downwind. The change in wind direction helps pinpoint the direction of lift.

the late kenny goodwin with the best td
The late Kenny Goodwin with the best TD trainer you can use: a pole and streamer as a visual indicator of wind speed and direction.

Thermal Plan

Armed with real-time knowledge by simply being aware and observant, you can approach the flightline to launch with a good idea of where to go. If you have a partner or timer, discuss what was observed before the launch so that you are both aware of the "plan." You each might not have the same conclusions, but by independently observing all of the signs, you can come to a consensus and decide where to go.

The most important information often comes during your actual launch and, as Skip Miller once said to me, "You must be prepared to change your mind during the launch if you feel or see something else."

Be sure to study Joe Wurts’ third-vector diagram that is included with this column to understand how to read thermals based on the wind direction and speed. Also consider the following tips.

  • Decisions during launch: Whether you launch via a winch or electric power, observe the handling of your model and the performance of the launch equipment. During a winch launch, you will notice a straining winch or higher tension when launching in lift.

    While flying an electric-powered sailplane, you will see a higher climb rate than normal if you launch in lift. If the lift just went by, you might find yourself launching downwind. Although a downwind winch launch might be lower than normal, continue in the launch direction to catch the lift that caused the downwind launch.

  • Pay attention: Your model is always talking to you. After you launch and you begin tracking a course to your "read," pay attention to what your model is telling you. Direct engagement with a thermal can mean that the tail is being pulled by inflow toward the rising air (making the model turn away from lift). Changes in wind speed (indicating direction and the proximity of a thermal) can be read easier when flying on a crosswind heading by watching the aircraft during this initial thermal-seeking phase.
  • Eyesight: Much of the observation needed to find lift and use it requires better eyesight than what you have naturally. You should obtain a prescription for long-distance eyewear and purchase a pair of special prescription glasses just for flying.

    I suggest ordering 50% amber-tinted sunglasses online from Zenni Optical. Don’t get polarized glasses—only amber tint is needed for optimal visibility. A prescription at Walmart and the glasses from Zenni will cost you less than $120. It’s the best investment you can make to earn some wood at your next TD contest.

Lost Sailplane Recovered

During the 2011 F3J Team Selection event in Cocoa, Florida, many sailplanes were lost in the woods during a windy weekend. One of those models was flown by Dave Bradley (the Junior on our team). In the weeks after the event, Jody Miller and I spent many hours searching the woods and only found one lost sailplane, Phil Barnes’ Supra.

Eight years later, in August 2019, a sailplane was found under the floor of a nearby home. The person who found it in 2011 was apparently a teenager who hid it under the house and forgot about it. The teen grew up and left home. His parents discovered the model under the mobile home in almost perfect condition.

Jody and I were Dave’s teammates at that 2011 contest, so we were happy to return it to him at the 2019 F3J Team Selection contest at Horse Feathers Airport in Virginia. This Pike Superior will fly again.

F3J Team USA

It is an F3J cycle again, and the team representing the US is strong. I have been tasked with raising funds to get the team to Slovakia for the F3J World Championship in July 2020. Please support your team by purchasing apparel or raffle tickets on the website listed in "Sources."

Until next time, fly downwind and soar!

dave bradley
Dave Bradley (center) was happy to get his Pike Superior back after it spent eight years in the Florida jungle.


League of Silent Flight (LSF)

Radio Carbon Art Productions

(888) 834-2261

Zenni Optical

(800) 211-2105

Team USA F3J

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