SlopeAerobatics.com – VTPR and slope aerobatics since 2007

by Eric Poulain

After many years of so-called traditional acrobatics, the addicts of Menez including myself, felt the need to practice their passion in a way somewhat unbridled. In other words: let off steam in some academic exercise that a columnist has called “voltige tres pres du relief” (VTPR).

Initially, our gliders were largely inspired by the great Quartz of Francois Cahour. We then had the desire to create machines better suited to our style of flying: thus were born the Sonic of David Luce and my Excalibur.

As you probably already noticed, performance gliders have a curious tendency to look alike: same shape, same profile, or almost. This reminds me of a certain Dolly aging faster than his shadow [Ed.??]. Every summer, I offered to try and sort out a number of models that (daring) friends entrusted me with their first contact with air; this has caused me to shake a little, to see.

Excalibur is the synthesis of these multiple tests. This is the feeling that the shapes of the time were defined: no aggressive lines, good side surface, rounded, nice look (Thierry finds himself an air of Donald. To each his references!) Anyway, this is a mutant.

Has remained define [with] the pen which as everyone knows an essential character in our activity: simple trapeze to facilitate construction, simple though effective ailerons (not full-span, not quadro, not high tech), no complicated wingtip shapes.

In terms of construction, I research the simplicity and cost reduced to its simplest expression. Look no carbon, nor kevlar, balsa at most, fiberglass, a little resin, PU glue and a few drops of plywood, the result to be light and easily repairable, to take a hit without stress.

To tell you about Excalibur, I chose to focus more particularly on the flight. This phase is the culmination of various cogitations and the inevitable construction. The area of application of this glider being large, we first discuss the flight called “traditional” (nothing to do with our bagpipes) and finally VTPR, the settings of the model being identical in both configurations.

Excalibur, as you guessed, is an aerobatics glider. Contrary to what is often observed (free advertising for others) you can make it fly in light winds. I hear the laughter already … aerobatics? Little wind? One thing is clear: to make progress in this discipline, we must fly often, so [the glider must be] for all conditions. It is useless to have a superb model of plastoc that costs over 3500 Francs (plastoc of the poor!) which stays on the ground for lack of sufficient dynamic range while the cronies are turning the crepe in the midst of handlaunch gliders [Ed.: I have no idea what this means, but the gist of it seems to be that it's better to have something that will fly in light lift rather than not fly at all]

Excalibur is piloted using three axes of control, which means that the rudder is not an accessory that can be ignored for aerobatics. Turns should be coordinated under pain of not being able to appreciate its amazing capabilities of scraper [Ed.: scraper = floater]

Despite its low wing loading (necessary for VTPR), the Excalibur is not afraid of the big time and is very penetrating. The profiles used are probably not strangers to this undeniable advantage.

With a bit of zef, aerobatics classic comes together with ease without a playful monster is absolutely necessary. May nothing prevents pushing like crazy on the handle, each has its pleasures!

Loops go straight fingers in the nose (this is only a phrase, please keep holding onto the handles!), including the most beautiful who turn parallel to the slope. Slight gain airspeed, pull, and we must not forget two things: correct a drift [with rudder] at the top depending on the wind and release the handle [elevator] so as not to tighten the loop. For what are the inverted loops, no problem either.

For barrels [rolls], a low acceleration enough to turn them without having to do too much correction. One can nevertheless execute them at the rated speed of the glider, but in this case, we must know how to play the drift [rudder] and depth [elevator] depending on the position of the device [glider].

The Excalibur restores well and its rudder is particularly effective permitting the chaining of reversals and double reversals in small spaces. Adjustments and plan, inverted flight requires little correction has depth and can even scratch in this position, remembering that in this case, the rudder is always necessary and it is reversed.

I believe I read that some think that the knife-edge of significant duration is a utopia in a glider. To have succeeded (and I’m not the only, does not it Biloune and others) with different models, I suggest you try it with the Excalibur. A tip: it is the only figure that requires a substantial speed gain. We push to the playful, is pulled slightly, it sends the ailerons to the switch to the bracket, then you put a background rudder (note: in the right direction, try, you will find) [Ed.: Yeah, the hard way! LOL :p ]. The elevator is then rudder and used according to the wind. When it goes well, it is possible to travel amazing distances.

All chained figures (vertical eight, Savoy knot, four leaf clover) are feasible without major difficulty. Despite this strong potential, the Excalibur is accessible to any pilot skilled in three axis flying. Particularly nice, the Excalibur is rarely in trouble. At large angles and no angle of attack, the stall comes late, with a moderate swing perfectly and catchability.

Its speed range is a surprising extent. Can bomber [Ed.: go fast] or be asked to bring gently in the palm of your hand (interesting if one does not scratch the paint of the fuse), without any risk.

For landing, other than in the hand, I do not use A.F. [no idea what this is] as a glider extends max light wind, better meet the ailerons (45*) like Lucien and Miametons. This parachute the Excalibur.

Before going further, it seems important to mention that the VTPR is not an exercise in kamikaze, practice fades, with no respect or space or people. The level of risk, excluding radio failure is virtually zero as long as certain rules are followed:

1) Never exceed the level of control: one must have a good mastery of classic aerobatics to try the VTPR.
2) Always announce [the glider's] passages and figures.
3) Figures are not made behind your companions
4) VTPR figures are made at the lowest possible speed

The simplest is the classic touch and go: you come in for a landing as gently, you stroke the grass (the sand or water for some …) with the belly of the time and one starts toward the hole. Attention should be able to hear the slight crunch that attests to the success of the maneuver. The trick is to appreciate the speed required for landing before the kiss off again. An alternative is to graze the grass (for example) with a wingtip or with the top of the rudder, implying in the latter case that we present on her back.

And nothing is easier to get [Excalibur] on his back, than a half-snap positive. It arrives flat and has a height compatible with the half-scale (not below 1.30 m for the Excalibur!). In the case of a half-snap to the right, send a bottom depth with pitch, and rudder and ailerons to the right (to help). The rotation is abrupt. To stop once on the back, releasing it while it grows. The accuracy of the judgment depends on the lightness of the wings. The negative half triggered a right to recover a flat, is a similar way: a bottom has bitten deep, drift to the left and ailerons to the right. Moreover, the half-triggered negative saving is a maneuver to get out of a delicate position at low altitude. Attention, it is recommended to train beforehand with water under the keel, except [for those who] love repair.

Series of half-snaps on the spot: wind speed must be greater than or equal to the rated speed of the glider, the figure tackles against the hole, a nominal height of the glider, the figure tackles against the hole, has height eye. It excecute successively triggered a half-positive and half negative snap and start again until the altitude is too low … We must note that at each full turn, the glider tends to go down and ‘taking it well, it is also a solution to land.

The reversals are, of course, part of the panoply of VTPRiste.
All combinations are possible.
For example:
- Depart back, slight altitude gain
- Small back reversal at low speed
- Touch and go rudder at the output of the reversal
- Half-snap negative
- Touch and go is flat
- And if possible, half-snaps positive …
- Landing in the hands

No, you are not dreaming and this is not pure fiction: with a little practice and sometimes a few tubes of glue, we get the desired result.