On Wednesday, October 3, 2012 9:17:51 AM UTC-5, jams wrote:
Hi all, I have recently become interested in gliding and have been exploring the aspects associated with the sport. I'm going to use the term 'standard glider' to represent any non-acro 15m glider, (ASW 19/20, Speed Astir, LS range, DG range, PIK20D etc) not standard class. I recently started looking at aerobatics and sailplanes certified for this. Started looking at datasheets for aircraft and most 'standard gliders' are semi aerobatic only, in addition to this some give g ratings. The most common I have found is +5.3 / -2.65. Seems to be almost a standard. When I started looking at what maneuvers 'semi acrobatic' gliders could perform, the standard list seems to be loops, spins, chandelle, spiral dive. I then came across some more advanced maneuvers like cuban 8, barrel rolls, inverted flight etc. I thought that these type of maneuvers would exceed the -g rating of -2.65, so wouldn't be feasible. Then I came across this you tube footage of a PIK20D doing some, what I think to be, serious aerobatics. http://www.youtube.com/watch?v=tSB-JAFqrhU Pretty sure there is some significant -g going on in some of these moves, however the PIK20D (according to the BGA datasheet) is only rated to -2.5g. So what I'm asking is: Is this still basic stuff, (just looks impressive too me!)? What sort of -g would be experienced in these maneuvers, would it exceed -2.65? Would other 'standard gliders' be able to do stuff like this (assuming they had the same g rating as the PIK)? I did think for a minute that this was a brave chap wondering what it would take to snap the wings off, but on translating the German it says its part of his bronze acro training. So it must be signed off by some CFI somewhere?! What do you think? One interesting thing I came across was the g ratings for the LAK-12...+6 -4...thats quite high up the g rating ladder, and pretty impressive for an 20.5m Open class machine! Cheers James -- jams

You obviously have never tried to push out to -2.5Gs! Seriously, unless you are into competition aerobatics, -1.0Gs would be a lot. All the basic maneuvers can be done without exceeding +3gs or so and without any negative Gs at all - it's not until you get into slow rolls that you get into any negative G, and unless you are doing outside loops, not much.

Glider acro (unless in a Swift/Fox, etc) is a relaxed, gentle form of the art. It's not about pulling a lot of G, it's about energy management, and not exceeding VNE.

But - DO NOT TRY ACRO IN A GLIDER (OR ANY AIRCRAFT) WITHOUT PROPER TRAINING, AN APPROVED GLIDER, PARACHUTES, AND AIRSPACE!

Seriously, gliders are so slick that something as simple as a barrel roll will end up exceeding VNE if not done correctly. And exceeding VNE is not good...

Kirk
66
Occasional glider acro pilot (ASK-21, G-103Acro, Swift S-1, Blanik L-13AC, Pilatus B4, LS4, LS6)