parallelogram stick

On Sun, 09 Jan 2011 18:20:39 -0800, wrote:

Kestrel's also had the parallelogram stick.

So does the Glasflugel Mosquito.

took very little time to get used to and was quite comfortable to fly
with.

The only parallelogram stick glider I've flown was a DG-300. My
impressions were the same as yours.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Sun, 09 Jan 2011 18:33:57 -0800, Bruce Hoult wrote:

On Jan 10, 7:07Â*am, Timinnc wrote:
Sorry guys, can't find the answer via search, but what is a
parallelogram stick?

This is one, in a Club Libelle.

http://farm3.static.flickr.com/2746/...cb753ae4_b.jpg

Sorry if it's not too clear but I wasn't especially taking a photo of
the stick!

The stick grip is on a vertical shaft that comes down only as far as the
horizontal tube, to which it is rigidly welded. There are two pivoting
vertical tubes coming down from the middle and front of the horizontal
tube. The front one is obscured by the foam.

That looks quite similar to the Mosquito stick, which uses a vertical
leaf spring as the front support for the parallel tube. IOW the leaf
spring serves as both front support and as the trim spring.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

At - Show quoted text -

We have a DG300 fitted with a parallelogram stick based at our site.
It seems to be more prone to pilot induced oscillations on aerotow
than most!

Derek C

More to do with the pilot i would think. The several mosquitos, dg100s etc
on site have no problem.
Incidentally one side effect is that there is more leg clearance if you
are a short arse like me.

On Jan 10, 8:42*pm, Nigel Pocock wrote:
At - Show quoted text -

We have a DG300 fitted with a parallelogram stick based at our site.
It seems to be more prone to pilot induced oscillations on aerotow
than most!

Derek C

More to do with the pilot i would think. The several mosquitos, dg100s etc
on site have no problem.
Incidentally one side effect is that there is more leg clearance if you
are a short arse like me.

I checked out a certain generally very competent Crown Services Club
member for aerotowing on a belly hook in a two seater and he did it
perfectly. He then went on to get into one of the worst PIOs I have
ever seen on his first attempt at aerotowing their belly hook only
club DG300, fortunately abandoning the launch before he actually broke
the glider. Back to another two-seater check and he was perfect again.
With some difficulty I persuaded him to take another aerotow in the
DG300 and he was OK the second time. I think he must have been caught
out by the general twitchiness in pitch of this type and the unusual
movement of the stick, which was different to what he was used to.

Derek C

On Jan 9, 12:07*pm, Timinnc
wrote:
Sorry guys, can't find the answer via search, but what is a
parallelogram stick?

--
Timinnc

There is a flying quality called stick force per G. A parallelogram
helps keep a person's hand and arm from decreasing the fore and aft
stick forces with +-g loads. This is not the only factor involved with
stick force, by a long shot.

Originally Posted by n7ly

On Jan 9, 12:07*pm, Timinnc
wrote:
Sorry guys, can't find the answer via search, but what is a
parallelogram stick?

--
Timinnc

There is a flying quality called stick force per G. A parallelogram
helps keep a person's hand and arm from decreasing the fore and aft
stick forces with +-g loads. This is not the only factor involved with
stick force, by a long shot.

Wow..... Thanks for all the input!

On Jan 10, 11:19*pm, Derek C wrote:

DG300 and he was OK the second time. I think he must have been caught
out by the general twitchiness in pitch of this type and the unusual
movement of the stick, which was different to what he was used to.

Derek C

Derek -

As a DG-300 owner I'd argue that the ship isn't "twitchy". However,
the control forces are fairly light (pleasantly so, when you go for an
all-day flight). Most modern glass ships are like this, and don't
present any particular safety risk. Side-note: If you learn on a
Schweizer then EVERY glass ship is going to feel twitchy by
comparison! :-P

Also - all parallelogram sticks are not created equal. I disliked the
Zuni II parallelogram stick (put my wrist at an odd angle); but I love
my DG-300 stick. So much of the ergonomics and control of any
aircraft come down to personal preference, and there's NO substitute
for putting your butt in the seat and trying it out (even if its just
on the ground)!

As for people talking about G-loading affecting the stick force -
here's a little sketch I made for some power-pilots to explain the
problem with a "normal" (pivoting) stick that is offset to the rear:
http://picasaweb.google.com/lh/photo...eat=directlink

Enjoy,

--Noel

On Jan 13, 6:54*pm, "noel.wade" wrote:
On Jan 10, 11:19*pm, Derek C wrote:

DG300 and he was OK the second time. I think he must have been caught
out by the general twitchiness in pitch of this type and the unusual
movement of the stick, which was different to what he was used to.

Derek C

Derek -

As a DG-300 owner I'd argue that the ship isn't "twitchy". *However,
the control forces are fairly light (pleasantly so, when you go for an
all-day flight). *Most modern glass ships are like this, and don't
present any particular safety risk. *Side-note: *If you learn on a
Schweizer then EVERY glass ship is going to feel twitchy by
comparison! *:-P

Also - all parallelogram sticks are not created equal. *I disliked the
Zuni II parallelogram stick (put my wrist at an odd angle); but I love
my DG-300 stick. *So much of the ergonomics and control of any
aircraft come down to personal preference, and there's NO substitute
for putting your butt in the seat and trying it out (even if its just
on the ground)!

As for people talking about G-loading affecting the stick force -
here's a little sketch I made for some power-pilots to explain the
problem with a "normal" (pivoting) stick that is offset to the rear:http://picasaweb.google.com/lh/photo...dCFQ?feat=dire...

Enjoy,



Noel,

Fortunately we don't have any Schweizer gliders in the UK! I don't
know if your DG300 has a nose hook, but the DG300s at our site only
have belly hooks and have a reputation for being a bit twitchy on
aerotow. I can't say that I found them difficult, but then I had quite
a few hours in a Standard Cirrus (ultra-light controls with an all-
flying tailplane) before I first flew one. The pilot who had the PIO
problem had previously aerotowed a Slingsby Sport Vega on a belly hook
with no problem and was fine when checked out on a Grob G103 and a K13
aerotowed on their belly hooks.

Thank you for your diagrams. The issue is that if you pull back on the
stick you will induce positive g, which may cause you to inadvertantly
pull the stick back even further. A sort of runaway situation that
could lead to a loss of pitch control or a PIO.

Derek C