What is VTPR?
Originally intended for FUN flying with the boys on a Sunday afternoon, VTPR is fast becoming popular in the US. This fun style of RC slope flying is basically aerobatics very close to the ground with varying model air speeds and design. Since its inception over two decades ago in France it has now become quite sophisticated beyond merely fun flying. It is approaching a competitive spirit that is producing new model designs in the US being flown on many geographic slope contours as well as becoming more and more precisely descriptive in its understanding.
At the moment the Americans are actively exploring this sport over what exactly VTPR is. We are seeing all kinds of new aerobatic maneuvers from ultra-light and the typical medium weight models from novice to expert pilots. The VTPR movement in the US is in a state of growth. Two styles have emerged as favorites, that being traditional French VTPR and an American style VTPR that encompasses tighter and quicker maneuvers. Regardless of which style is preferred the following core tenants of VTPR remain the same.
As per Pierre Rondel in 2005 he quotes: "But more what we call in France VTPR - Voltige très près du relief (translation: aerobatics very close to the ground), this is a very spectacular type of aerobatics that requires very good skills and no fear".
And from the author I quote: "Any aerobatic maneuver, figure or trick interpreted by the pilot that is performed successfully, and in whole directly above and close to the terrain, at any desired air speed". Example: 2 half rolls in succession at eye height or around one and a half wingspans above the ground is a VTPR maneuver.
What VTPR is not - Maneuvers, figures and or tricks performed beyond the slope lip in open air space or far away from the terrain. Far also means figures above 3 wingspans at their lowest point. These maneuvers should be termed as "Aerobatics Totale".
The dividing line from VTPR to Aerobatic Totale style can be clouded and very opinionated but when all is said and done, the French built the core VTPR principle around these four simple words - Low, Lower, Lowest & Fun.
VTPR gliders range in wingspan from 1.5m to Unlimited and are designed with very light and durable airframes made to cut the air and choreograph some of the most amazing maneuvers ever seen. They enjoy confronting danger and succeeding in delivering a very reliable stance all the way through the extreme moves that a pilot can muster. They like to hover, stall roll, perform off angled figures and just about everything under the sun one can imagine. They particularly perform with grace and beauty in all positions. Its important every square inch of the model be designed and built in such a way that purposely accomplishes performance with ease at all times. All summed up, we want a VTPR model that will seem to defy gravity during flight as if it were dangling from a string. The ultimate goal is to design a plane that makes it easier and easier for the pilot to fly difficult and dangerous maneuvers hence these models are in a constant state of development.
Every form of model glider flying requires a particular space and proper conditions suited to obtain the maximum performance the model is designed for. Not all gliders are alike by any means and are strongly defined by the environment they perform in. This is especially true of VTPR style of slope flying. Some slopes are better than others for the best looking VTPR result. Particularly with very close to the terrainslope aerobatic maneuvers we want a slope to have certain wind and lift conditions for success or disaster will result with a broken plane more often than not.
For general slope identification and shape there are three basic types of slopes covered here to help you visualize and understand their positive and negative VTPR traits. Added to the slope geography is wind direction, wind speed, temperature and atmospheric pressure considerations the novice VTPR enthusiast would do well to learn as he gains experience.
This simple graphic below shows the most desired slope contour and wind direction characteristics in order to perform VTPR aerobatics to the fullest and easiest degree. A nice long shallow slope with lateral wind direction flowing over the glider wing is the most efficient for VTPR. The "fly box" is large and open for all manner of VTPR. To the common slope flier this may seem odd or not what they have learned andflown in slope for many years. Perfectly understandable but we want to fly very close within inches of the ground at times in which the near horizontal wind forces net us the best result. When entering close to the terrain you will find with practice this is in fact what we VTPR flyers desire the most in a slope.
Below we can see the more common inland slope contour you are probably very familiar with. The 45 degree or so slope angle causes the oncoming wind to propel upwards and over the slope creating an upward lift band and rotors behind the slope lip. This at first glance looks like a nice flying slope and it is for general flying and aerobatics. But in the context of over ground VTPR it poses some problems. First the "fly box" is reduced and as a result requires the pilot to be extra careful maneuvering close to the terrain. Second there will be a noticeable increase in model air speed. Third to fly nice flowing VTPR close to the ground with minimal risk of damage to the model, the plane needs to be designed and built lighter than normal. This introduces a "hover affect" trait in the model in order to help the pilot fly close to the terrain in an easier less stressful session.
The graphic below shows a very stark difference to the most ideal slope #1. These slopes or cliffs are primarily ocean coast sites where the bikinis are more attractive than this shape of slope to try VTPR aerobatics. The lift band is very narrow and requires the VTPR pilot to have excellent skills to keep his ship over the ground right at or just behind the lip. Depending on conditions it may be virtually impossible to maintain over-ground aerobatics! Only attempt this slope if you have much experience and don't mind cracking up your model. It is possible to momentarily perform certain maneuvers while stabbing your plane at the slope lip and flying the plane back out into the upward lift band out front then diving back to the ground area of the site, you might even be able to fly the plane a little behind with momentum enough to carry the plane through a maneuver if you time it right. It is recommended you choose a model that is very lightweight and durable and study the possibilities very closely.
This is the most enjoyable and interesting aspect of VTPR Aerobatic slope flying. How does one get into VTPR and why would he purposely fly his prized model in dangerous territory? In just a few words - shear exhilaration painting a beautiful flight! And an affinity with extreme aerobatics in general. VTPR pilots are a very small group of fliers around the globe that have been bitten with the desire to push a model and they're skills to the absolute limit where few have purposely ventured. They come from all kinds of model glider backgrounds but one thing they all have in common. The need is not only to get the model the lowest in a very clean and controlled manner and have fun doing so. The goal you see for a VTPR pilot is to be able to perform the most difficult figures and maneuvers possible - but do them with ease. This takes a lot of stick time at the slope and a lot of model and radio set up experimentation to where the two are perfectly co-joined at the hip. It is almost as if the model becomes ones favorite tool of the trade rather than a model. It is a lot of fun flying VTPR but it also has a very serious attention getting persona about it that sets VTPR pilots apart from the rest of the slope aerobatic field.
As previously mentioned there aren't very many VTPR pilots and for good reason. I believe an asset for a new VTPR pilot is one who has great eye-hand coordination from an early age. Maybe one who has competed in a individual sport or one who is very proficient with video games and the like. Ultimately, a pure love for silent flight that allows one to express his art with a glider. All of these experiences are of great help. On the other hand a "newbie" could come into the sport cold turkey and with nearly no experience just may be able to hook onto the VTPR concept and take right off. I think many of our younger generation pilots would fare well in this sport. Whatever the case, if you are looking for the maximum in all-around slope aerobatics, VTPR is your choice.