Glider Shapes

Gary Emerson wrote:
brtlmj wrote:
Standard control system layout (no parallelogram stick)

Excuse my ignorance... what is a parallelogram stick?

Bartek

The standard configuration has the stick pivoting forward and aft as
well as side to side. The parallelogram stick SLIDES forward and aft,
but pivots side to side. Some people really like it, but it's a minor
design by numbers.

Excuse any appearance of anality, but the parallelogram sticks I've seen
in Mosquitoes did not *slide* forward and aft. Rather they moved
forward and aft on a 3-sided parallelogram linkage (having beautiful
bearing movements). There were 2 always-parallel, essentially vertical
pieces connected at the top by an always-horizontal piece. (Imagine a
cereal box end-on, long sides horizontal. [Approximate] mid-pitch
position would be short sides vertical. Forward would squash the 'gram
to the left (say); aft to the right.) I can't remember if the
Mosquito's hand grip attached to a 3rd upright welded to the top
horizontal, or extended aft and up from an extension of it.

Parallelogram geometry is such that vertical acceleration forces exerted
by one's hand in turbulence are muted due to near 90-degree interior
angles of the parallelogram in normal flight regimes. I thought it
quite elegant; it's certainly more 'turbulence benign' than a sharply
aft-pointed stick or S-curved stick, where positive G induces aft stick.
(Tangentially, George Moffat attributes at least one fatality to an
owner-added S-curved stick; apparently a strong negative gust at low
altitude and high speed resulted in an inadvertent pitch-down.)

My Zuni's side stick (and the sole HP-18 example I've seen) had sliding
pitch implementations rather than pivoting. Every sliding pitch
implementation I've played with (think Cessna/Piper power plane) has had
MUCH more pitch friction than that in Mosquito parallelograms.
Completely different concepts...

Regards,
Bob W.

Excuse MY ignorance !

Is there an advantage of the parallelogram configuration over the
conventional stick in the manufacture or in the handling ? For a
"universal" glider, the simpler it is with all the specs already given
(L/D, retractable gear, etc...), the more appealing it would be.
Eventually, though, ease of manufacture and price will be the
clinchers.

Cheers, Charles

The standard configuration has the stick pivoting forward and aft as
well as side to side. The parallelogram stick SLIDES forward and aft,
but pivots side to side. Some people really like it, but it's a minor
design by numbers.

Thanks!

B.

Gary Emerson wrote:
Brad wrote:
This sort of follows up on the future of soaring thread, but
is more
focused on the sailplane design aspect.

Ok.....here is the scenario: the powers that be have decided
that once
again the soaring community needs a sailplane that
represents Joe
Sailplane Pilot. Joe sailplane pilot wants a sailplane that
will get
him where he wants to go, but on a budget. Joe's a smart
guy..............he knows a thing or two about sailplanes;
having
spent
considerable time poking and prodding their various bits and
pieces.
He
decides he wants a composite ship, now he
want's......................what????

Here is where you fill in the blanks.............if for no
other
reason
than to whack away at the keyboard.....or not!

Cheers,
Brad


Start with perhaps an obvious observation.

If the end result doesn't look kinda like something that's
already
popular (Discus, LS-4, ASWG-XX, etc.) then it's not likely to
be as
popular as one would hope. Consider Genesis and PW-5. They
are good
gliders, but the odd shape sways people away from them.


With that said...

Gotta have retractable gear.

I'd suggest 40/1 is a minimum target, mid 30's is not going to
sway
people away from the number of ships that already exceed that.

Be able to accomodate most pilots. Pilot comfort w/ chute is
a must.

Easy rigging and automatic hookups

No flaps

Have room in the fuse for future model expansion to include a
sustainer
at least and a small fixed tank for gas.

No gel coat would be a huge plus, particularly for the harsher
climates.

Standard control system layout (no parallelogram stick)

Nose and CG release options

No nasty handling characteristics.

Sprung gear and a good brake

Tilt up panel (at least as an option)


Sounds like an HP-24. Except the flaps.

--
Regards,
Doug


--
Posted via a free Usenet account from http://www.teranews.com

A Ballistic Recovery Chute.

Mike Schumann

"Brad" wrote in message
...
This sort of follows up on the future of soaring thread, but is more
focused on the sailplane design aspect.

Ok.....here is the scenario: the powers that be have decided that once
again the soaring community needs a sailplane that represents Joe
Sailplane Pilot. Joe sailplane pilot wants a sailplane that will get
him where he wants to go, but on a budget. Joe's a smart
guy..............he knows a thing or two about sailplanes; having
spent
considerable time poking and prodding their various bits and pieces.
He
decides he wants a composite ship, now he
want's......................what????

Here is where you fill in the blanks.............if for no other
reason
than to whack away at the keyboard.....or not!

Cheers,
Brad



--
Posted via a free Usenet account from http://www.teranews.com

On Fri, 04 Jan 2008 14:06:14 -0600, Gary Emerson
wrote:
[snip]

Room for 2+ batteries.

And for the standard 21st-century USAn arse.

rj

On Jan 4, 4:53*pm, wrote:
Excuse MY ignorance !

Is there an advantage of the parallelogram configuration over the
conventional stick in the manufacture or in the handling ? For a
"universal" glider, the simpler it is with all the specs already given
(L/D, retractable gear, etc...), the more appealing it would be.
Eventually, though, ease of manufacture and price will be the
clinchers.

Cheers, *Charles

Charles -

Supposedly there is an advantage in the arm movements required for
pitch adjustments. The Parallelogram stick means that if you feel a
sudden "G" force up or down, it won't likely cause you to move the
stick (whereas if a pivoting stick was already forward or aft some,
the "G" force would tend to make it go in that direction more with the
increased weight of your arm and the lag in response-time of human
muscles, and anatomical arrangements and whatnot).

However, I've tried a couple of Zuni sticks (the sliding kind) and a
DG-303 stick (true parallelogram) while on the ground. Both were a
bit weird, and I did NOT like the Zuni stick. My reasoning is this:
The straight push-pull arrangement requires that you move your whole
forearm to change the stick position (pitch up or down), whereas a
"traditional" stick just requires small wrist movements. Therefore I
think its easier to be sensitive and have fine-motor-control with a
traditional stick (wrist and hand muscles and nerves are WAY more
coordinated than forearm and elbow muscles). I also wonder about the
ability to feel "stick forces" through the push-pull or parallelogram
arrangements. Don't want to over-control at high speed or miss the
cues that you're slowing in a thermal turn and risking mushing or
stalling...

Just my $0.02 - I've only been flying for a couple of years at this
point, so I'm certainly no sage!

Take care,

--Noel

Is there an advantage of the parallelogram configuration over the
conventional stick in the manufacture or in the handling ?

Why not just skip back in time, put in an F-16 non-moving sidestick
(uses strain gages) connected to a fly by wire computer, full digital,
quad redundant (FOUR batteries?) and hook the autopilot up to SeeYou
Mobile? The IGC approved logger feeding altitude to SeeYou (Version
26) should allow the pilot to take a nap during that 4,000 k flight...

Oh, sorry, I'll shut up, since I'm just a lowly 1-26 driver. Yeah,
some think it's a shape only a mother could love, but I love mine --
as the article in AOPA Pilot said: "Love the one you're with."

-Pete
#309

Brad wrote:

Here is where you fill in the blanks.............if for no other

A generous amount of panel space would be good.

IMO the minimum is space for 8 instruments (compass, T&B or AH, 2
varios, ASI, altimeter, radio, transponder or FLARM) and at least two
instruments will need to be 80 mm. It should also be possible to mount a
GPS or PDA without obscuring anything. This should work in nicely with a
roomy, comfortable cockpit if the panel is a Discus/ASW-20 style rather
than the DG/LS pedestal arrangement.


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

The sailplane of the future, heck, the sailplane of NOW should have a
finish that never requires sanding nor refinishing in order to
maintain it's performance. It should come out of the factory in
perfect condition and stay that way. Waxing would be "optional", and
only for those who need some quiet time with their glider.

Not that I'm trying to put refinishers out of business. No! There's
a lot of old ships that will still need refinishing for years to come,
but the NEW ones should have surfaces that will never need to be
refinished.

Oh yea, this glider of the future with the no-refinish surfaces,
should have performance capability better than ASG-29/Ventus 2/DG808/
LS10/eta/EB28, etc...


Ray Lovinggood
Carrboro, North Carolina, USA