Flapped Glider Recommendations...

On Jan 9, 9:12 am, Andreas Maurer wrote:
an advice: Don't stick too close to numbers. Performance numbers of
glider differ vastly depending on who measured them (Johnson or the
German Idaflieg), and, more important:
Sheer performance numbers are only one part of the truth.
In reality you are not going to notice if your ship has two points
better L/D or a slightly better sink rate.

Bye
Andreas


I totally agree with you on the numbers deal - especially when it
comes to manufacturer's specs! And I know that small variances in
finishing and mold changes over the years can affect the L/D by a
point or two. But at least with Johnson (and other practical flight
tests) I have demonstrated numbers that have actually been measured
*in flight* - not theoretical or predicted numbers.

And I understand that I won't notice one or two points of L/D - that's
why I'm going for a jump from ~31:1 to at least 38:1. That big of a
spread I _will_ notice.

The reason I use sink-rate as a measure of performance is because it
directly affects climb rate in a thermal, and just trying to figure
out which airplane "thermals best" is subjective, dependant upon
conditions, and plain tough to get an accurate reading on (especially
because so few people have flown a wide range of gliders over the
years - so there's little common basis for direct comparison).

Dave - The 1f is cool; but the two that I've found talk about having
rough finishes. A glider that old/cheap is just not worth the cost to
refinishing... Again, its not that I don't like them; but do you
think that an $18k LS-1f is a better purchase than a good-condition
LS-3 at $24k? The difference in monthly loan cost is not an issue for
me (I'm not rich, but I've carefully budgetted to handle $8k to $10k
down and a $15k to $18k loan).

Having only flown my Russia, Blanik L-13s, and SGS 2-33s I think I
ought to follow through with my original plan to visit Minden sometime
soon and try their Mini, LS-3a, and LS-4. I need some seat-time in
15m ships to see how they compare to my Russia...

Thanks again, all! The conversation is certainly good for helping
organize my thoughts and refine my opinions.

Anyone have any info about SZD-55's? I had two people email me
privately to say that they thought I could pick one up for around my
$30k limit - but those folks were in England and I haven't heard
anyone from the USA talk about this model. It got plenty of favorable
reviews when it came out... ??

Take care,

--Noel

On Wed, 9 Jan 2008 10:12:08 -0800 (PST), "noel.wade"
wrote:

But at least with Johnson (and other practical flight
tests) I have demonstrated numbers that have actually been measured
*in flight* - not theoretical or predicted numbers.

I'm pretty sure that at least for all German gliders younger than 30
years you can trust the published performances - in Germany the
idaflieg measuy every glider type with extremely elaborate yet precise
procedures - if the numbers they got were far off, word about that
would spread quickly.
Dick Johnson also does a great job, but he has a couple of performance
numbers of certain gliders that are simply far off since he is not
able to put the same amount of work into his research as idaflieg
does.


And I understand that I won't notice one or two points of L/D - that's
why I'm going for a jump from ~31:1 to at least 38:1. That big of a
spread I _will_ notice.

Yup.
But trust me - you won't feel a difference between 36:1 and 38:1...
but you are going to feel the difference between 31:1 and 1:36. vbg

I am pretty sure that any glider that was produced after the ASW-15 is
going to fit your performance demand - all of them have at least 38:1.

The reason I use sink-rate as a measure of performance is because it
directly affects climb rate in a thermal, and just trying to figure
out which airplane "thermals best" is subjective, dependant upon
conditions, and plain tough to get an accurate reading on (especially
because so few people have flown a wide range of gliders over the
years - so there's little common basis for direct comparison).

Forget that approach to judge a glider.

Pure sink rates don't work - you also need to incorporate the airspeed
in your judgement since this decides about turn radius. Not to mention
the "feeling" of the glider - LS-7 and ASW-24 have a very good sink
rate on paper, yet their airfoils need to be flown very precisely
compared to other gliders, so most pilots ended climbing significantly
worse than older gliders with a higher sink rate.

My advice: base your judgement on ergonomics (cockpit, handling on
gound and in the air, trailer) - this is going to have a far greater
influence on your performance than pure glider performance numbers.

Having only flown my Russia, Blanik L-13s, and SGS 2-33s I think I
ought to follow through with my original plan to visit Minden sometime
soon and try their Mini, LS-3a, and LS-4. I need some seat-time in
15m ships to see how they compare to my Russia...

I promise: you are going to be blown away by their performance - and
you are not going to be able to judge which of them has the better
performances. Especially flapped ships need a couple of dozen of hours
to get used to if you haven't got experience on flapped
high-performance ships yet.

Anyone have any info about SZD-55's? I had two people email me
privately to say that they thought I could pick one up for around my
$30k limit - but those folks were in England and I haven't heard
anyone from the USA talk about this model. It got plenty of favorable
reviews when it came out... ??

Few SZD-55s around, but one german top pilot used to fly one for a
long time and was very satisfied - so it seems it's comparabley in any
way to current (German) standard classgliders. You can get a
comparably young 55 for the same price as an aolder German ship.
Definitely worth a closer look.


Bye
Andreas

On Jan 9, 5:07*pm, Andreas Maurer wrote:

But trust me - you won't feel a difference between 36:1 and 38:1...
but you are going to feel the difference between 31:1 and 1:36. *vbg

Hey, I took a flight in the front seat of a DG-1000. Want to talk
about a differencein L/D? heheheheh...

Pure sink rates don't work - you also need to incorporate the airspeed
in your judgement since this decides about turn radius. Not to mention

Fair enough. This is also where flaps can help - moderate flap
application = lower speed thermalling; so as long as the drag isn't
too bad from the flap deployment you should have a net gain in climb
performance as you can make tighter thermal turns.

But my Russia stalls at around 39 kts indicated (I am 200 lbs and 6'
tall - a big American *sigh*)... The aircraft really likes a 45-
degree thermal turn at about 48 - 50 knots (min-sink speed is around
42kts so that jibes well with the load-factor of a 45-degree turn).

I think most of the gliders from the late 70's and early 80's have
similar stalling speeds - so as long as I stick to models that have
the good roll control and responsiveness that I seek, their ability to
have a tight thermalling circle should be adequate.

I promise: you are going to be blown away by their performance - and
you are not going to be able to judge which of them has the better
performances. Especially flapped ships need a couple of dozen of hours

Well I've flown my Russia AC-4 *alongside*:
Apis 13m (equal in climb, small but noticeable difference in height
per mile of cruise),
PIK-20B (could out-thermal it, but not keep up on glide),
1-34 (Russia was noticeably better all around; though not by a big
margin),
Chinook S 17m (I was slightly worse in climb, no comparison in
glide),
Open Cirrus (I had the slight edge in climb w/small circles; but the
damned Cirrus just defies gravity and lumbers along for miles),
Blanik L-13 (I was slightly better in glide, slightly better on a
ridge, and noticeably better in thermals),
DG-1000 (hahahahaha! "alongside" is almost a misnomer...)

Plus I have my Private Pilot's License in single-engine aircraft (got
that before starting in gliders) - so I'm familiar with flaps and that
stuff...

way to current (German) standard classgliders. You can get a
comparably young 55 for the same price as an aolder German ship.
Definitely worth a closer look.

Huh. Lot of varying opinions about that it seems! Some people seem
to think I could get one for around $30k, others think $50k - $60k...
interesting. Can I have one of you "cheaper" people call some SZD-55
owners and convince them to sell it for less? *grin*

Thanks all, don't be shy to pile on more feedback! :-)

--Noel

On Wed, 9 Jan 2008 17:48:11 -0800 (PST), "noel.wade"
wrote:

Fair enough. This is also where flaps can help - moderate flap
application = lower speed thermalling; so as long as the drag isn't
too bad from the flap deployment you should have a net gain in climb
performance as you can make tighter thermal turns.

Unfortunately it's not that way, at least not in the flapped gliders I
fly.

Usually you don't thermal a flapped glider significantly slower nor do
you climb better than a non-flapped ship.
The advantage is that you can ballast a flapped glider to higher wing
loadings (while still being able to thermal halfways slowly) to
increase your cruise speed - and of course the flatter polar at higher
speeds even without ballast.

In weak weather there's really no noticable performance difference
between flapped and non-flapped gliders - but the better the weather
(=higher wing loading and higher cruise speeds), the bigger the
difference.


But my Russia stalls at around 39 kts indicated (I am 200 lbs and 6'
tall - a big American *sigh*)...

LOL... I'm as heavy as you, but 7" taller...

I think most of the gliders from the late 70's and early 80's have
similar stalling speeds - so as long as I stick to models that have
the good roll control and responsiveness that I seek, their ability to
have a tight thermalling circle should be adequate.

Indeed.

Well I've flown my Russia AC-4 *alongside*:
Apis 13m (equal in climb, small but noticeable difference in height
per mile of cruise),

The Apis has pretty good numbers on paper, but I suspect that its low
wing loading makes penetration at higher speeds bad compared to a
ballasted Standard class glider.


Plus I have my Private Pilot's License in single-engine aircraft (got
that before starting in gliders) - so I'm familiar with flaps and that
stuff...

Not even similar, I'm afraid.
Perhaps I was spoiled by the ASW-20 that way my first flapped glider,
but at least in the 20 I had the feeling that I needed about 50 hours
until I felt I had mastered it halways because especially the 20 needs
pretty precise adjustment of the flap setting to the current speed,
wing- and g-loading, meaning that the left hand is nearly as busy as
the right one.
The LS-3 is easier to handle (wrong flap settings have less negative
influence on the performance), the optimum is probably the DG-300 and
LS-4... lol.

Think twice if you really need flaps on your glider (and if youre
willing to pay them) - if the weather is really weak in the area you
fly in, flaps won't give you a noticeable performance advantage.


Huh. Lot of varying opinions about that it seems! Some people seem
to think I could get one for around $30k, others think $50k - $60k...
interesting. Can I have one of you "cheaper" people call some SZD-55
owners and convince them to sell it for less? *grin*

The problem on oyur side of the pond is the very limited number of
available used gliders. Move to Europe. Plenty of really good used
gliders here.

Bye
Andreas