Is PTS just the latest marketing buzzword? Not by a long shot. I believe this concept will forever change the way people get involved in RC aviation. Progressive Trainer System—PTS—accomplishes two milestones, neither of which has been done before. It lets you learn to fly with an airplane that looks cooler than a typical blocky trainer, and it allows you to upgrade along with your progress as a pilot. NO MORE FLYING BOXES For as long as there have been RC airplanes, new people interested in flying RC have not wanted to fly a high-wing trainer. Hang around a hobby shop for a while, and it becomes clear that most perspective RCers want to fly a P-51. But starting out with a P-51 was always nothing short of a ridiculous notion. I have seen a lot of people state that they wanted to start in RC with a P-51, but in all of those years, I know of none who actually succeeded in doing it. That is until very recently. To make a P-51 into a trainer, we had two options: either deviate so much from scale that it looked very little like a P-51 and then try to market what we had, or figure out how to make a good rendition of a P-51 behave like a trainer. Obviously the first option didn’t appeal to us. So Step One in developing this model was to design a P-51 that was a great aerobatic sport model—one that any experienced sport modeler would want. That was the easy part. We then listed all of the attributes of this great sport model (not unlike any good sport model) that needed to be changed in order to make it a trainer. They really boiled down to three issues:
SPEED CONTROL This was the easiest correction and was addressed with three separate features: Speed Brakes – These forward-facing boards attach to the landing gear struts and create a lot of drag, which reduces the top speed of the model. This is a feature we borrowed from some RC jet and older F3A pattern designs. It’s very simple and very effective. Once the modeler is ready to speed up, they can be removed in a few seconds. Flaps – When in trainer mode, the flaps are deflected down 22 degrees. This adds additional drag to help reduce speed even more, making landing speed slower, and increases the lift the wing produces to aid in landing ease. Once you’re ready for a greater challenge, the flaps can be neutralized in a few seconds. 3-Blade Propeller – The Evolution® Trainer Power System includes a 3-blade propeller that is a great training tool. It keeps speed from getting too high, yet still pulls the model very well. This helps a lot to keep the speed down while training. However, once the speed brakes are removed and the flaps are neutralized, the P-51 will still move out pretty well with the 3-blade prop.
This was a big challenge. Conventional landing gear or tail draggers are traditionally known to be difficult to steer on the ground. We experimented with a variety of landing gear lengths, forward sweeps and separations between the wheels with the hope of getting the handling close to as good as a typical tricycle landing gear-equipped trainer. What we ended up with was a model that ground-handles in a truly superior manner. Unlike high-winged tricyclegeared models, the P-51 won’t tip up in a crosswind. It is very easy to steer and hard to over-control like some other trainers. It’s almost impossible to nose over, even when flying off of the roughest grass fields (I even flew it off of a freshly harvested soybean field with no problems). Typical takeoffs can be accomplished with three control inputs. Move throttle to full power. Give one slight rudder correction. Wait till the P-51 is up to flying speed and pull up elevator.
PREVENTING TIP STALLS Keeping a wing that would be aerobatic and look like a P-51 wing, yet give it the stall characteristics of a trainer, was the biggest challenge by far. Fortunately, we have a few of the most respected minds in aerodynamics available to consult. After discussing the objective with both Dr. Michael Selig and George Hicks, we agreed that using NACA droops on the leading edge of the wing tips would do the trick. Dr. Selig provided the airfoil shape for the droops. After testing the new configuration, we were amazed. The droops added to the otherwise semi-symmetrical P-51 wing and completely changed the stall character of the model. It became impossible to snap-roll, spin or come close to a tip stall. Exactly what’s needed for a trainer. By molding them out of transparent, high-impact plastic, they are invisible when the model is flying, so the wing shape looks unchanged. After all training is done, they can be removed in a few seconds, and the P-51 is transformed into a capable aerobatic model. TIME TO MOVE UP It’s no longer necessary to learn to fly, then “move up” to a more advanced airplane. The concept of PTS is for the airplane to grow with you. As you progress from basic flight training to more advanced flying and start to remove the changeable features of the P-51, the model transforms in the way it flies so you’ll never get bored with the PTS after you have learned to fly. That means you won’t have to spend more money, or get a second and third model to challenge your piloting skills as they develop. The P-51 stays right with you. In fact, you could learn to fly and progress all the way to a rippin’ sport pilot without ever buying a second airplane. We’re bombarded with terms like “revolutionary “ and “groundbreaking” in advertising, but, in all honesty, I believe that the P-51 Mustang PTS is exactly that. We’ve field-tested the concept and had several beginners make their very first solo flights on the model. Add to that the smile on their faces and the satisfaction they got from knowing that they just learned to fly and soloed on a P-51 Mustang, and that defines success that’s hard to beat. | ||||||||||||||
Revolutionizing Radio Control with PTS
- Written By: HorizonRC.com
- Posted: 2005-08-09
GROUND HANDLING
