On Mar 25, 3:59*am, bagmaker
wrote:
;687487 Wrote:





Bill said:
"... the tension should be the maximum safe value."

OK, let me try this again. Maybe you'll understand this question:

1. In your opinion, what is the maximum safe value expressed in g, for
he initial launch phase?
2. Who else agrees with your position that the initial launch phase
should be aggressive? In this thread alone, nobody agrees with you.
Where are all these people? Mr. George Moore has also said he
advocates a slower launch than you do on the Yahoo groups site.
"Bill has advocated higher ground acceleration rates than I am
generally comfortable with."

I haven't heard a single person support what you advocate. Whatever
you find, please with verifiable quotes.

- And I don't know were your get your sense of what rude is, but
publicly and falsely claiming I am misrepresenting my identity without
any proof on your part what so ever, certainly is rude behavior.

I would support a fair bit of what Bill says, which may be why my
previos post has been ignored.

Many of our sports members fall into the old dogs and new tricks area,
I have a feeling the more experience one has in anything, the more they
push against change, especially as we grow older.

I must disagree with Dereks' statement on measuring tension as well, it
is a simple thing to do. Perhaps it hasnt been done, sure, but its not
hard. (Caveat- I sell loadcells and measurement equipment for a
living)

As I have stated, If we can identify we have a problem (we do, people
have died) why would we not change? Technology is allowing change,
embrace it.
If, with respect of time, we see we were wrong and can change back,
what harm? At least we tried.

We can set up winches to do any damn thing we like, every time,
regardless of wind gusts, temperature changes, altitute differences,
ballast, number of pilots, student requirements, winchperson ability,
emergency airspace violations etc, etc. So lets!

If you dis-agree, dont fly off the new winch, simple!

Bagger

--
bagmaker

Thanks for that.

This discussion always gets the "Safety Nazis" wringing their hands
and wailing every time. ( But never, ever, producing any hard data.)
The thing is - it's mostly a trivial "tempest in a teapot".

To get the absolute maximum acceleration possible for a glider, just
divide a gliders flying weight into its specified weak link strength.
(Tost weak links are now calibrated to +or- 5%) That value is always
around 1.2G - if you don't believe it, read your manual. If you try
to accelerate the glider with more force than that, the link breaks in
the takeoff roll and the glider never gets airborne.

Since even the most conservative old fart thinks than .8 to .9 G is OK
for most gliders, this whole frightful affair is all about an
approximately .3G range which is buried in the 'noise'. Most pilots
can't detect the difference.

I've had brand new Tost weak links fail in the rotation phase on many
occasions as a result of too much cable tension from one of those
"underpowered US winches". I was nowhere near the limit of down
elevator authority. The most recent involved a 2-33 whose CG is at
least 3 feet above the hook and whose tiny horizontal tail severely
limits down elevator authority.

Again, the disclaimer, there are a very few mostly old gliders with a
problem which thankfully are very rare in the US. Pilots of these
should check with knowledgeable people for the special launching
technique required. Virtually all gliders in the US winch just fine.

I strongly suspect the problem is isolated to the UK, where they do
fly old gliders, and has to do with a particular new 'powerful winch'
which is capable of enormous force in first gear and which shifts to
second gear at some unknown and uncontrollable point during the
rotation phase. The tension data which IS available for this winch
looks pretty scary.

Dereks voluminous criticism of computer controlled automatic tension
winches stems from the fact that HIS favorite winch has no such
controls and he's afraid that US winch builders using Automatic
Tension Control will steal the market.

Everyone has experienced the imprecise surging when backing a car with
an automatic transmission to align a tow ball with a trailer hitch.
Imagine trying to control the acceleration a 1000 pound glider with a
drive train intended for a 6000 pound road vehicle.

Anyone who thinks any of this is not true, needs to produce some valid
measurements to the contrary. I believe validated data.