parallelogram stick
Timinnc
Sorry guys, can't find the answer via search, but what is a
parallelogram stick?
--
Timinnc
Derek C
It is where the stick just moves backwards and forwards on a
parallelogram mechanism, as opposed to being bottom hinged. It's
supposed to stop pilots putting in unintentional movements due to g
loadings.
Derek C
SoaringXCellence
I have pictures of a parallelogram stick assembly if you'd like to see
them.
Contact me
c i r r u s c f i ( a t ) g m a i l . c o m
GM
Tim,
the elevator input is given by moving the stick back and forth on a
straight line rather than rotating the stick around one single hinge
point. To make matters worth, the commonly used sticks are typically
off-set from the hinge point towards the rear. High vertical
accelration can induce an unwanted elevator input. As Derek pointed
out, pilot induced oscillations due to vertical accelerations is not
an issue with these sticks. The Glassfluegel H303, H304 (incl. the CZ)
Mosquito and maybe other types have this type of stick.
Uli
brianDG303
Almost all, if not all, of the DG series gliders have them.
Martin Gregorie
DG 300 for sure, but not, IIRC the DG1000 and I seem to remember a
'normal' stick in the DG-500.
--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
asw22...@gmail.com
wrote:
DG1000 is "normal"
Kestrel's also had the parallelogram stick.
took very little time to get used to and was quite comfortable to fly
with.
Al
Bruce Hoult
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/2746/4378550696_67cb753ae4_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.
ContestID67
the same as "unintentional movements due to g loadings"?
I have flow a DG-101G, DG-300 and DG-303 with a parallelogram stick.
I also fly an assortment of ships without a parallelogram stick.
Honestly, I don't know if I have noticed much of a difference.
However, the DG (with parallelogram) has a CG release while the others
(non-parallelogram) do not. Would a parallelogram stick help prevent
ballooning (with ugly consequences). If so, I am all for it.
- John
Derek C
wrote:
>
> - 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
Martin Gregorie
> 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 Gregorie
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.
Nigel Pocock
>
>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
>
on site have no problem.
Incidentally one side effect is that there is more leg clearance if you
are a short arse like me.
Derek C
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
n7ly
wrote:
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.
noel.wade
> 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/SEHsoog31GpIkb6AOJdCFQ?feat=directlink
Enjoy,
--Noel
Derek C
>
> 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