Ventus B, Discus ect aileron connecting rod/slide lube

On Tuesday, February 3, 2015 at 7:15:37 AM UTC-7, Bob Whelan wrote:
On 2/3/2015 5:31 AM, Don Johnstone wrote:
At 23:52 02 February 2015, HGXC wrote:
On Monday, February 2, 2015 at 3:00:05 PM UTC-5, Don Johnstone wrote:
At 15:26 01 February 2015, wrote:

Some judicious snippage...

I own a Ventus and I have mine lubed at the annual, I have the openings
in
=
the wing like Dick Johnson suggested. If Schempp Hirth didn't want this
to
=
be lubed then they would have used a different bushing when they made the
g=
lider. All gliders have short comings. The glider has been flown over 30
ye=
ars and like all popular gliders over time, pilots find ways of
addressing
=
imperfections and every glider has some.

Dennis

Why is it that some glider pilots feel they know better that the qualified
engineers and designers who design and build the machines they fly. Maybe
using an unapproved lubricant on material that you do not know the
composition of, which might be damaged is unwise but drilling a hole in the
structure to do it, that is stupidity of the highest order, such is life I
suppose. I doubt that the "opening" made was properly sealed to unsure that
moisture could not damage the GRP structure which is hygroscopic, my
advice. Do NOT purchase a glider owned by these people.
It is true pilots have a long history of finding incorrect ways of
addressing imperfections, proves the old maxim I suppose, if flying was
difficult engineers would do it.


Evidently, the original question touched upon "a topic of religion." One
church believes that gliders as-received from manufacturers cannot possibly be
improved by mere humanity unassociated with the original design process (and
to attempt improvement places one in the category of the devil's spawn). The
other church believes that use-/age-related issues will inevitably appear, and
might (if not should) be reasonably addressed by subsequent owners. True - at
least in the U.S. - for sailplanes licensed with (see below) an Approved Type
Certificate or licensed Experimentally.

In my view, there's sound reasons for both views, and in an ideal world, both
can peacefully co-exist. Full disclosu I'm a(n aerospace) degreed
(U.S.-based) engineer, but one who's convinced original designers were NOT
(all apply): all-knowing; incompetent. In other words, designers and the
design team are humans like the rest of us, though with (perhaps) some
specialized training, and (definitely) some specialized interests...again
normal human conditions.

The U.S. is fortunate to have a healthy, vibrant, amateur-built aircraft
licensing category, from which - perhaps - some cogent conclusions about this
particular religious topic may be drawn. As I type, approximately 20% of the
U.S. power, single-engine, 4-or-less seats general aviation fleet is licensed
"Experimental Amateur Built" (a presently increasing proportion), the rest
having Approved Type Certificates. Taken as a whole, the EAB category accident
frequency is (statistically and) significantly higher than the ATC category as
measured against fleet/licensing numbers. Unsurprisingly (in my view) the
percentages have a significant first-/early-flight bias (for engine/fuel and
loss of control reasons, mostly); thoughtful readers can probably make
accurate guesses why (an exercise and validation beyond the point I'm trying
to make with this post). Once beyond that bubble, EAB and ATC accident rates
are (arguably) identical. I expect (but am not certain) accident *causes* are
similar as well (when comparing similar classes of pilots/flight, e.g. Visual
Flight Rules piloting).

My conclusions:
1) "Sound airplane design practices" are not limited solely to factories and
their design teams.
2) The weakest link is generally the nut at the top of the stick.

Stated another way, pretty much every form of human design screwup/oversight
possible in general aviation flying machines (e.g. sailplanes) has been made
long, long ago, and "best practices" are pretty much available (and arguably
well known) to anyone inclined to learn from others' experiences. We're well
beyond the "secret guild stage" of aircraft structural design knowledge, and
the "smoke and mirrors" of ignorance-based myths.

That knowledge availability, along with the tendency of those geekily inclined
(most engineers, and many non-degreed people as well) is why I'm OK with
belonging to the Church of Future Improvement is Possible.

On the other hand, the World Wide Web has made it easier for everyone (e.g.
via YouTube) to easily see that Darwinism remains a potent human genealogical
force. Ignorance is potent, often more quickly than knowledge. Hence I'd never
try to convince members of the Church of Don't Mess With Factory Stuff to
change their beliefs.

Clint Eastwood was right: A man's got to know his limitations.

Further, who hasn't heard the truism: All generalizations are
false...including this one. In my view, there's at least one truism that is
NOT false: Perfection is never an option.

True in glider design, too. The trick is to know - or at lest to remain within
- one's limitations.

YMWV
Bob W.

P.S. I believe Dick Johnson was a degreed aeronautical engineer. His entire
working life was spent in the engineering field, and his extracurricular
soaring-and-sailplane-design-and-testing-related body of work was prodigious.
He likely passed on from heart failure in his mid-eighties while flying the
Ventus he owned for decades - the one in which he drilled lube access holes.
Make of all that what works for yourself!

Yes, nice post, Bob

One thing I wonder about is the continued use of Nylon blocks as cable/pushrod fairleads since there are better engineering plastics available today. For example solid UHMWPE is stronger than Nylon and has a coefficient of friction equal to Teflon. It also seems utterly immune to ageing effects. I know a number of Homebuilt/Experimental people who use it for fairleads.

At 14:15 03 February 2015, Bob Whelan wrote:

Evidently, the original question touched upon "a topic of religion." One
church believes that gliders as-received from manufacturers cannot
possibly
be
improved by mere humanity unassociated with the original design process
(and
to attempt improvement places one in the category of the devil's spawn).
The
other church believes that use-/age-related issues will inevitably
appear,
and
might (if not should) be reasonably addressed by subsequent owners. True
-
at
least in the U.S. - for sailplanes licensed with (see below) an Approved
Type
Certificate or licensed Experimentally.

In my view, there's sound reasons for both views, and in an ideal world,
both
can peacefully co-exist. Full disclosu I'm a(n aerospace) degreed
(U.S.-based) engineer, but one who's convinced original designers were NOT

(all apply): all-knowing; incompetent. In other words, designers and the
design team are humans like the rest of us, though with (perhaps) some
specialized training, and (definitely) some specialized interests...again

normal human conditions.

The U.S. is fortunate to have a healthy, vibrant, amateur-built aircraft
licensing category, from which - perhaps - some cogent conclusions about
this
particular religious topic may be drawn. As I type, approximately 20% of
the
U.S. power, single-engine, 4-or-less seats general aviation fleet is
licensed
"Experimental Amateur Built" (a presently increasing proportion), the rest

having Approved Type Certificates. Taken as a whole, the EAB category
accident
frequency is (statistically and) significantly higher than the ATC
category
as
measured against fleet/licensing numbers. Unsurprisingly (in my view) the

percentages have a significant first-/early-flight bias (for engine/fuel
and
loss of control reasons, mostly); thoughtful readers can probably make
accurate guesses why (an exercise and validation beyond the point I'm
trying
to make with this post). Once beyond that bubble, EAB and ATC accident
rates
are (arguably) identical. I expect (but am not certain) accident *causes*
are
similar as well (when comparing similar classes of pilots/flight, e.g.
Visual
Flight Rules piloting).

My conclusions:
1) "Sound airplane design practices" are not limited solely to factories
and
their design teams.
2) The weakest link is generally the nut at the top of the stick.

Stated another way, pretty much every form of human design
screwup/oversight
possible in general aviation flying machines (e.g. sailplanes) has been
made
long, long ago, and "best practices" are pretty much available (and
arguably
well known) to anyone inclined to learn from others' experiences. We're
well
beyond the "secret guild stage" of aircraft structural design knowledge,
and
the "smoke and mirrors" of ignorance-based myths.

That knowledge availability, along with the tendency of those geekily
inclined
(most engineers, and many non-degreed people as well) is why I'm OK with
belonging to the Church of Future Improvement is Possible.

On the other hand, the World Wide Web has made it easier for everyone
(e.g.

via YouTube) to easily see that Darwinism remains a potent human
genealogical
force. Ignorance is potent, often more quickly than knowledge. Hence I'd
never
try to convince members of the Church of Don't Mess With Factory Stuff to

change their beliefs.

Clint Eastwood was right: A man's got to know his limitations.

Further, who hasn't heard the truism: All generalizations are
false...including this one. In my view, there's at least one truism that
is

NOT false: Perfection is never an option.

True in glider design, too. The trick is to know - or at lest to remain
within
- one's limitations.

YMWV
Bob W.

P.S. I believe Dick Johnson was a degreed aeronautical engineer. His
entire

working life was spent in the engineering field, and his extracurricular
soaring-and-sailplane-design-and-testing-related body of work was
prodigious.
He likely passed on from heart failure in his mid-eighties while flying
the

Ventus he owned for decades - the one in which he drilled lube access
holes.
Make of all that what works for yourself!

Up until today I was firmly of the opinion that EASA and their regulation
was an unnecessary imposition on gliding. I had always believed that no-one
who flew a type certified glider would make structural modifications
without consulting the type certificate holder and obtaining their approval
for a modification, I simply did not believe that anyone could be THAT
irresponsible. I seems I was wrong, which is nothing new. I suppose that
EASA is a necessary evil while there are those who think that such behavior
is acceptable. What worries me most is that these actions are taken by
people who are described as well respected and qualified engineers. It
certainly increases my understanding of the attitude of EASA to FAA
licensed engineers.
I am well aware that in the past such modifications were made to simple
wood and fabric constructed gliders, cutting and patching a hole in fabric
or indeed metal skins is a completely different matter to drilling holes in
a GRP structure, the best that can be said is that such action has not
failed, YET, or maybe not.
To say that a course of action is ok because A.N Other did it and got away
with it is not safe practice, especially when it encourages those without
knowledge to try an "inspired" fix.
If you can produce a note of compliance, a relevant AD or tech note, from
the type certificate holder I will of course take it all back.

I would suggest not lubricating any kind of plastic bearing. Dust will stick to the lubricant and increase wear. Depending on the lubricant used the plastic may also start swelling. You can easily make thinks a lot worse by wrong lubrication. Keeping the bearing clean and the pushroad polished is probably the best approach. If you want to use a lubricant then maybe a thin film of something on a silicon or teflon basis would be good. In any case make sure the lube is compatible to the sleeve material and will not cause swelling.