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RC Soaring

Sage Advice - R/C Soaring: The Basics

The focus for TPG in the month of October is on the newcomer to R/C soaring. With this in mind, I’ll cover a few basic topics that may be helpful to the beginner.

First, let me welcome all those who are reading this newsletter for the first time and/or who have just been bitten by the R/C habit. New members are the life-blood in any organization, and in TPG, we rely on newcomers to maintain the vitality and enthusiasm that’s so apparent in our club. We were all beginners at one time and most of us benefited from the knowledge and experience that fellow club members provided. It’s in our best interest to ensure that the same encouragement is available for the next generation of soaring enthusiasts.

Since this discussion is intended for beginners, I’ll use the KISS technique and keep this simple. The question I’m asked most frequently by beginners is, "what keeps the glider up without a motor?" The answer of course is "lift".

Each glider has an inherent minimum sink speed (MSS) and in the absence of lift, the glider will come down at least at its MSS if not considerably faster. MSS for the gliders we fly vary from about one to several feet per second. More efficient gliders have a lower MSS and this translates to longer air time without lift. Given a 400 foot launch height and a glider with a MSS of 1.5 fps, a typical flight without lift will last about four minutes. However, remember that in lieu of lift, all gliders are gliding downward.

To emphasize this relationship, let me mention a conversation I had with Mark Smith a few weeks ago. Mark is a many times national soaring champion and has designed and developed numerous gliders during his career. Most people will remember him as Mr. Dynaflight. Mark and I were discussing modern construction techniques and the improvement offered in the efficiency of the typical competition glider. Marks’ candid comment brought this all into perfect focus when he said, "You know Fred, the only thing that hasn’t changed in the last 20 years is that if you don’t find lift in the first three minutes, you’re going to be walking to retrieve your glider." Apparently some things never change!

So, the name of the game in soaring is to find lift. This lift needs to be at least as strong as the MSS of your glider if you intend staying up. If you want to climb, the lift needs to be even stronger. As soaring enthusiasts, there are many types of lift available to us. Let me briefly discuss the two we use most often.

Thermal Lift

Thermal pilots rely on differential heating to spawn rising air masses or thermals. Although we typically fly in flat terrain, there are still trip points that cause thermals.

We use winches to get our gliders up into the air. A winch launch can generate up to about 500 feet of altitude before we release from the winch and go in search of lift. Our search patterns usually include the topographical features that breed thermals as well consideration for a shift in wind direction or speed, a change in cloud coverage or formation as well as many other visible indicators of lift. If we’re successful, we not only stay up as long as we like, but can climb until only our limit of vision and common sense restrain us.

Thermal lift can be very capricious. Lift patterns change from season to season, day to day and even moment to moment. No two days are exactly the same. The challenge always remains in thermal soaring because you’re never able to truly master the game. There are simply too many variables to control. Consequently, the excitement and wonderment stays in the sport no matter your level of skill.

I liken the search for lift in thermal soaring to that of the fisherman for fish. The fisherman casts his lure into the water and never knows exactly what to expect. Some days he catches his limit and on others, his only consolation is a day of relaxation. However, the serious fisherman can increase his chance for success by thoroughly understanding his prey, fishing at the right time of year, during the right time of day, in the right spot and with the right bait and technique. Likewise, the thermal pilot doesn’t know when he launches if he’ll be able to remain airborne. However, with the help of club mentors, the beginner can be taught the subtle techniques required to extend thermal flight time.

Slope (Ridge) Lift

A second type of lift used by soaring enthusiasts is slope or ridge lift. This lift is caused by the prevailing wind striking a slope and being forced to deflect upward. This gives the wind an upward vector or lift and makes sustained soaring possible. The only feature necessary to ensure useable slope lift is a relatively unobstructed slope with a nearly perpendicular prevailing wind direction (within about 30 degrees).

As in thermal soaring, if the slope lift exceeds your MSS, you have the potential to stay up as long as you desire. All that’s required is a persuasive hand toss into the lift band and up and away you go. Small and light slope soaring gliders can remain aloft in winds as low as three knots.

Racing is also done in slope lift and when the wind is stronger, the racing gliders add weight in order to increase their speed potential. Racing speeds at the slope often exceed 100 mph and catastrophic mid -air collisions have been known to happen. In fact, the world speed record for all types of C aircraft is held by a glider. If you’re into adrenaline pumping action, the slope is the place for you.

So these two types of lift—thermal and slope—translate to the two main soaring disciplines within TPG. Each has its many different formats. Thermal soaring includes thermal duration, hand launch, hand tow (F3J), scale, nostalgia and multitask (F3B) soaring. Slope includes racing, aerobatics, combat and scale. Each format has its advocates and offers unique challenges.

What plane should I get?

The next most frequently asked question is "what’s the best glider to learn with and how much does it cost?"

With the advent of nearly indestructible EPP foam trainers, I would be hard pressed to recommend anything else. As a beginning pilot, you can expect to crash many times before mastering the spatial relationships and control inputs necessary to keep your glider in the air. With an EPP foam trainer, your time isn’t spent in the shop making the inevitable repairs but in the air. This will rapidly accelerating your learning curve and you won’t suffer the discouragement and expense of repeated crashes. The TG-3, from Dave's Aircraft Works and available at Discount Hobbies, seems to be the best of what’s available for flight performance. In fact, Joe Wurts won the recent and prestigious Rose Bowl two day two meter contest flying a TG-3.

The cost of the DAW TG-3 is about $70 and the building time is minimal. No special tools, skills or techniques are required to build the glider and maintenance is minimal.

What kind of radio?

Regarding your radio equipment, I recommend you start with a somewhat simple radio system. You will probably go through numerous interim gliders before the features of a full computer radio are anything more than additional complication. Besides, even after moving up to a computer radio, you can still fly your hand launch or simple slope gliders on your relatively inexpensive first radio. The cost of a reliable first radio system will be somewhere between $120 and $180.

So we see that the total cost to get started in this hobby is somewhere on the light side of $250. I guarantee that you’ll not find an alternate to R/C soaring that will provide the endless hours of enjoyment, satisfaction and challenge that are yours for the asking.

So how do you get started? Reading this newsletter is a good beginning. In addition, you will want to join the Academy of Model Aeronautics (AMA) and the Torrey Pines Gulls. The membership column in this newsletter will have additional information. By coming to the monthly meetings at the San Diego Aerospace museum, you’ll be able to get more immersed in the sport, learn where you want to focus your attention and meet many new friends.

The next step will be to show up for weekly training sessions either at the thermal field or at the slope. After a few weeks of introduction, you’ll be able to tell if this is a hobby you want to pursue. If so, I’m sure any club member will be happy to help as you develop your skills with building and flying.

I recommend that you do your learning at the slope instead of at the thermal field. The reason for this advice is simple. At the thermal field, you’ll probably be limited to only a minute or two before your glider is on the ground and needs to be launched again. This limits your learning progression. At the slope, with sufficient wind and someone to help in case you become disoriented, it’s possible to stay up for hours. I’ve seen kids learn to be totally self sufficient at the slope in one day!

One caveat is not to do your training at the Torrey Pines Gliderport. Although instruction is available at Torrey Pines, there’s just too much conflicting traffic nearby. A mid air collision with a hang glider by an unqualified beginner doesn’t set the professional tone that TPG wants to foster. Alternate and uncrowded sites are available at San Clemente, Oceanside, Encinitas, Poway, Lake Hodges, Santee, etc.

Eventually, you may want to pursue this sport to the next level which is competition. If so you have the added bonus of numerous past and present national champions within our club to guide your training. If you have an aptitude and the desire you’ll have the option of joining the TPG Soaring Team which competes throughout Southern California and occasionally makes field trips to the AMA Nationals.

Basically, you have the option to take this sport to whatever level suits your needs be it sport flying or serious competition flying. Both are very actively pursued in TPG.

So you see, the only real impediment to enjoying the wonderful world of R/C soaring is your participation. Just come on out and do it! Welcome to the Torrey Pines Gulls.