Radio Control Pylon Racing
Aaron "AJ" Seaholm [[email protected]]
Look—race season is on the horizon
We are deep in the heart of winter here in the great state of South Dakota, not unlike most parts of the Pylon Racing universe. Spring is not too far off, though; soon races will be filling up our calendars and adrenaline will fill our veins.
This month's column is intended to spur some thought about how you will get around the pins faster and more consistently in 2011. I hope that these topics will also help increase your fun-per-race ratio this upcoming season.
Flying the Course—Fast
Now is the time to be thinking about how to make improvements on the course this season. One area that can pay dividends in the form of lower times is learning about the physics of pylon models.
Before you skip to the next section, let me try to reel you back in. I promise not to go all engineer on you and get ultratechnical. Basic knowledge of aerodynamics will help by offering a few more speed knobs to think about and perhaps dial in.
Martin Hepperle's Aerodynamics of Model Aircraft website contains some excellent information related to the physics of racing model aircraft. He takes a deep technical dive on airfoils, engines, propellers, and a number of other interesting topics. I highly encourage you to check it out and absorb as much information as you can.
Go to Martin's site and double-click on the "Index" tab near the upper left corner of the home page. Select section "E." Under "engines" and "models," choose "pylon racing (F3D)." Click on "A Comparison of Pylon Racing Airfoils." Near the bottom of the page is a section titled "Pylon Racing Simulation." This study seeks to determine the ideal pylon racing course shape (think overhead view) from a mathematical physics model standpoint. The mathematics take into account lift and drag profiles, turning radii, and a host of other variables. The study concludes that a course with equal-radii turns between unarcing straightaways provided the lowest times for a given lift coefficient.
After observing hundreds of heats flown by the fastest pilots in the country, I will add a slight variation. I do not have the cool math to back it up, so you will have to trust me: a slightly arced line from Pylon One to Pylon Two can also help trim off some time. This is primarily because of the decreased angle through the turns where induced drag is very high.
Think about it like this. If a model enters Pylon Two at a 90° angle to the line between pylons Two and Three, it will turn for 180° before exiting back toward Pylon One. During that time, the induced drag—the byproduct of the lift required to make the tight turn—is decelerating the airplane. Therefore, if you can slightly round off the straights, you can decrease the angle at which the model enters the turn and decrease the angle required to get it pointed back toward Pylon One. This minimizes the distance in which the model is slowing.
If you do not consistently fly the arc from Pylon Three to Pylon One every lap, you put your caller at a huge disadvantage because the model travels a different distance each lap. Adjusting for slight changes in distance flown can make the tough job of calling nearly impossible. Therefore, I attempt to fly as straight as possible from Pylon Three to Pylon One, to give my caller the same distance traveled each lap.
In practice you have to be careful with this concept. It has been my experience that newer racers tend to make the arc too wide down the straight. That comes from the pilot's location in the center of the course and the extremely uneasy feeling generated from the model flying back at him or her from Pylon One. This leads to the pilot's releasing the turn early at Pylon One and naturally creating the slightly egg-shaped line between Pylon One and Pylon Two.
If you try to teach the slightly arced course, less experienced pilots will let off the elevator even earlier at Pylon One. The extra distance traveled in the straights then overshadows the benefit of the reduced drag angle through the turn.
The method I have used with success is to have the new pilot envision Martin Hepperle's ideal course with the two 180° turns and unarcing straights. This typically leads to a course that is closer to ideal than coaching the student to gently arc the straights.
Keep in mind that the time-saving techniques I described earlier can be blown away by missing your Pylon One turn. To drop your times to fast-guy and fast-gal territory, Pylon One will pay the largest returns for time reduction.
Why, you ask? Simply because the distance by which you miss Pylon One is multiplied by a factor of two. If you fly 100 feet past Pylon One, you also have to fly 100 feet back; you just added 200 feet traveled for that lap.
Again, this is where the pilot/caller relationship is so important. Find a good teammate, occasionally buy him or her dinner, and treat that person as a valued piece of your pylon racing endeavor.
Art of Calling—Launching
The launch in an RC pylon racing heat can really make or break the standings on lap 10.
If you, as the caller, are late or do not provide a straight, forceful launch, the rest of the heat can be an uphill battle. Being late on the push will place your pilot squarely behind other racers, who will provide many of those giant holes in the air to dodge.
Scott Causey and I have adopted the sprinter's-position launch technique. Travis Flynn, Gary Schmidt, Randy Bridge, and others have used this technique with great success. Watching this launch style from the sidelines usually makes its benefit apparent, as their pilots' models come catapulting into the lead.
It takes a while to get the hang of the position. But once it's mastered, this style will provide a great deal of consistency and velocity out of the hole during launch.
The other benefit of this approach is that it tends to keep the push parallel to the ground for a longer stroke of the arm. Rather than a swinging motion of the arm, you get an extension motion. That keeps the tail from coming up and buzzing the propeller—another mistake mode that can often lead to a 3- to 4-point meltdown heat. Been there; done that.
Find a launch position that is comfortable, and focus on becoming consistently quick with your stroke. Your pilot will thank you.
Staying the Course—To Move or Not to Move
In the February 2011 column I introduced the Conservatively Aggressive Game Plan concept. Another element to this concept is “Staying the Course—To Move or Not to Move.”
If you talk to most experienced pylon racers, they will tell you to hold your line; if you move, that is when a midair will happen. My approach to “holding your line” has a slightly different and more conservative spin, to help protect that substantial racer investment.
Having blasted many Combat models out of the sky before my re-entry into pylon racing, I began to recognize midairs coming. I will not claim that I was able to avoid them, but when two models go in for a kill on an intersecting flight path, boom—big wreck.
It is the same in RC pylon racing. If you try to fly the same line as your competitor, you will eventually try to occupy the same space. Pylon racers occupying the same airspace rarely ends well.
With this little pearl of wisdom, why would you hold a line that might be the same line as your competitor? There is plenty of vertical airspace on the course. Why not take advantage of it and reduce your racing expense?
Choose a line above or below your competitor’s flight path. Then hold your line by controlling your vertical spacing, and duke it out for 10 laps of clean side-by-side racing.
An integral part of picking a line is the knowledge of your competition’s flying style. I prefer 10–15 feet above the top of the pylons as the lead line. If you can get the lead, you will get to pick the line, and those following will need to slide up or down to avoid bad air.
Your competitor’s line will change with time and experience. Newer racers will not hold lines as consistently, which usually provides you with openings to get around them.
Ideally I prefer to pass at Pylon One, because my field of vision is much greater. For me, between pylons Two and Three is the most challenging; as you turn your head through this turn, your field of vision is limited. This makes it easy to misjudge where your model is and fly directly into a competitor while trying to squeeze past.
All of this sounds good in theory, but it will not provide much benefit until you can hold your line and fly consistently. So log those simulator laps and get in as much race stick time as you can. Race stick time adds the adrenaline factor that you cannot replicate any other way.
EFI Update
The Electric Formula 1 (EF1) crew has been hard at work.
Dan Kane sent in a picture of his new EF1 Shoestring, taken at the 2010 NMPRA Championship Quarter 40 race held last fall in Phoenix, Arizona. That is one fine-looking model.
Have fun and race hard!
Sources
- Aerodynamics of Model Aircraft — www.mh-aerotools.de/airfoils/index.htm
- National Miniature Pylon Racing Association — www.nmpra.org
Transcribed from original scans by AI. Minor OCR errors may remain.
