Aerobatics in semi acrobatic certified sailplanes

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

Pilatus B4 PC11, PC11A, PC11AF

Pilatus B4-PC11- Semi aerobatic,(+6.4, - 4.3). Cleared for outside loops, split S, Immelman, wing overs, chandelle, Lazy 8, Steep Spiral, Spins, Inverted -1G.

Pilatus B4-PC11-A - Fully aerobatic (+ 7.00, -4.79 g). Cleared for inverted flying, rolling manoeuvres inside and outside loops. Structurally as B4-PC11 but with toe straps, 5-point harness and increase down elevator travel.

Pilatus B4-PC11-AF - Fully aerobatic. Cleared as “A” model and for flick manoeuvres. As B4-PC11-A model but with rear fuselage strengthening to cater for flick manoeuvres. Strengthening may be factory fitted internally or external, fitted as a modification.

Span 15 meters, L/D 30-33ish

Example available (W&W):

Pilatus B4 PC-11
04-29-12 updated 07-18-12

s/n 237. Mfg 1976, TT 1650 hrs. Retractable gear.The glider was completely refinished in 2006: the finish is impeccable. BALL and Cambridge varios, iCOM radio, Winter ASI. Oxygen system.Easy to rig. Working, closed all-metal trailer. Always hangared - owned since 1986 by Pittsburgh Soaring Club. Last annual and maintenance/repairs performed by Gehrlein. Located at Bandel (22D) near Pittsburgh, PA.
https://plus.google.com/photos/10641...15575996995185

$17,300.00

This says the PIK 20 D is fully aerobatic if you fit toe straps and
a g meter

http://easa.europa.eu/certification/....024/EASA%20SA
S%20PIK-20D%2020110428.pdf

although the video shows rolls and inverted flight. the pushovers
are probably fairly low speed (watch the asi)


At 14:17 03 October 2012, 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

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)

On Oct 3, 5:29*pm, "kirk.stant" wrote:
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-JAFqrhUPretty 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)

Look at SZD-59 (+7/-5) more than you need when you screw up.

http://szd.com.pl/en/products/szd-59-acro

Thanks for all the input.

I have found out a fair bit more info on aerobatics since I posted this question. I think a better way of asking the question would have been: What aerobatic manoeuvres can a 'semi-aerobatic' sailplane perform!?

I have amassed quite a bit of info on the subject now, some interesting technical stuff that suggests that you cannot overstress a well designed sailplane at Va no matter what you do. I will have a read up on it all and post something here with my findings.

Kirk,

Your sentence: '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.' Sums up exactly what I'm interested in. I dont want a pure acro aircraft, because I dont want to do anything to mad but would like to be able to explore more than just loops and chandelle during flights.

Also having found what G forces are generated in the figures i'm interested in (in the PIK aerobatics supplement), and your comment about not much neg G occurring, suggests that most sailplanes could handle what the PIK was doing in the video anyway.

Regards

James

On Thursday, October 4, 2012 8:02:37 AM UTC-4, jams wrote:
Thanks for all the input.




Kirk,



Your sentence: '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.' Sums up exactly what I'm

interested in. I dont want a pure acro aircraft, because I dont want to

do anything to mad but would like to be able to explore more than just

loops and chandelle during flights.



Also having found what G forces are generated in the figures i'm

interested in (in the PIK aerobatics supplement), and your comment about

not much neg G occurring, suggests that most sailplanes could handle

what the PIK was doing in the video anyway.


Regards


James

Successfully executed positive G maneuvers are not a problem for many standard category gliders. But, there's a good reason why most of them are not approved or not recommended for acro. Failed maneuvers can quickly go badly wrong and put you into a situation where you can rapidly exceed the speed and load limitations. Rolling over the top in an overly aggressive stall turn or dishing out on an aileron roll would be two examples. When I was routinely doing a lot of acro in an L-13AC, it was the "oopsies" that really tested the limits, and this was in a glider that is much less slick than the high-performance ships in your examples.

No it doesn't.

At 20:04 03 October 2012, Peter Thomas wrote:
This says the PIK 20 D is fully aerobatic if you fit toe straps and
a g meter

http://easa.europa.eu/certification/....024/EASA%20SA
S%20PIK-20D%2020110428.pdf

although the video shows rolls and inverted flight. the pushovers
are probably fairly low speed (watch the asi)


At 14:17 03 October 2012, 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

No it doesn't.

At 20:04 03 October 2012, Peter Thomas wrote:
This says the PIK 20 D is fully aerobatic if you fit toe straps and
a g meter

http://easa.europa.eu/certification/....024/EASA%20SA
S%20PIK-20D%2020110428.pdf

although the video shows rolls and inverted flight. the pushovers
are probably fairly low speed (watch the asi)


At 14:17 03 October 2012, 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

As the owner of a Pilatus B4AF, and with some experience on B4/21/Fox, I feel I can at least give some hints.

I started with some figures on Utility class gliders. These often have max G ratings of +5.3 and -2.65 in my experience, although this is at Va speed. At Vne they often are limited to +4 and -2,
which is to take flying through strong thermals into account as far as I know.

The G-limits on gliders and allowed figures are two different things. Especially the high-performance gliders pick up speed fast.

I found that a truely Aerobatic-class glider (which often have +7 and -5 rating) is also suitable to learn figures on. In other words: if you screw up badly you will still not easily damage the
glider.
Think about kicking the rudder too late in a stall-turn and then ending up in an unintended tail-slide.

Also, the high-performance gliders often have a very laid-back body position for the pilot. In the DG-303 Acro handbook the pilot is warned about this, since G-awareness is lower in a reclined
position. And thus the risk of accidentally overstressing the aircraft.

In my B4 I fly rolls, inverted flight, spins, rolling turns (rolling and turning combined), tailslides, stall-turns and cubans (both forward and reverse).
I often have roughly +5 and -2 on the G-meter after a practice run. The +5 is during stall-turn pulls (to get a nice line) and the -2 is achieved during the pushing in rolling turns.
I would say for the first inverted flight and rolling (see the German Prufungsprogramm) you wouldn't go beyond +5 and -1.5 (achieved when pushing out your speed in a Split-S maneuver).

Long story short: I would recommend you learn to fly aerobatics on a Aerobatic-class two-seater. Then, if you become addicted, get yourself a B4/SZD-59/ASK-21.