Kestrel 19 - T59D Manual

Hi all

If anyone has an electronic version of the T59D manual I would much appreciate a
copy. I do have a paper version came with serial #1771. Unfortunately the
quality is poor and many of the diagrams are illegible (high acid paper + 30 years)

As an aside - I have the standard question - what is the real/realistic max L/D
of this beast.


For what it is worth I attempted to soar with the owner in the Kestrel, and me
in my Std Cirrus. Cirrus in club racing trim, with mylar gap seals, polished
surfaces and every possible gap sealed, but no ballast. Wayne brushed the worst
of the dust and mud drops (from the swallows in the hangar) off the top surfaces
on the Kestrel. No gap seals at all - not even tape...
Unfortunately this handicap was not enough to allow us to fly even remotely
together... The book says 1:44 - but I am not clear if that is for the 17m
version. It certainly appeared to be better to me - my Cirrus manages ~1:36 and
I was simply unable to stay in touch with the Kestrel. At 140 km/h, after 17km
for me he was at 24km, with the same height loss - (At 30km he was at 60km,
although he had lost 1,500" relative to the Cirrus at this point, due to me
thermalling so the comparison fails)

Simple extrapolation of the figures suggest 1:53 which is unlikely. Just
wondering what the number is.

I know a fair difference is probably because of better pilot and conditions, but
in this case we were flying very close together. The only part where I stayed
even remotely close was the 200 kph final glide - it looks like the longer wings
give greater drag here and the Kestrel was less "ahead" of the Cirrus after a
20km dash than the cruise experience would have indicated. He got there a lot
faster pulling out ~3km but with similar height loss...

She may no longer be competitive in any current racing class, but the Kestrel is
a serious XC machine. So any information on real world performance?

1/44 for the 19, and 1/43 for the 17 are the published numbers.

For the US Sports class the K19 is handicapped at 0.859 at 993lbs (dry
with pilot), K17 at 0.910 at 838lbs, and interestingly a LAK-12 at
0.865 at 1059lbs. All have the same Wortmann airfoils on the inner
and outer spans, though the K19 is generously filleted at the root.
The LAK inner panels are only flaps, whereas at least the Kestrel 19
has full span flaperons, though the inner panels only deflect half as
much as the outer panels. It's more elegant in control harmony than
the LAK. Well sealed, a series 1-3 K19 will thermal quite comfortably
down to 38kts in +2, though many prefer a notch at +1.5. The LAK
thermals nicely down around 40kts in +2 or T. A series 4 K19, is
heavier with ~250lb higher gross and one owner told me he liked
thermaling about 50kts in his series 4. I encountered him one day in
the UK and couldn't understand why he seemed to be thermaling so fast,
so we chatted about it later. Not sure how many series 4 were ever
built. I think the difference in being comfortable thermaling in +2 in
my Kestrel may be due to the addition of the mylar seals top and
bottom. Without them, I think pilots prefer in the +1.5 notch.

Kestrels run very well when conditions warrant 70kt+ cruise and will
run away from your Std Cirrus in short order, especially into wind. A
well prepared even more so. On a weak day, you might stick for a while
as they are heavy and don't climb as well in weak conditions. I could
readily out run, but not out climb my old 19m Open Cirrus in the
Kestrel 19. Shifting flaps in a Kestrel is like shifting gears in a
sports car, lots of fun and noticeably effective. Seldom need to
re-trim, as it's the same trigger trim setup as a Libelle it's quite
easy. Despite, not having mylar, that Kestrel 19 probably does have
the original internal seals. Like the control harmony, shifting flaps
in the LAK is not quite as well defined and there's more re-trimming
involved. The T-tail mass of the Kestrel is quite a bit more than the
LAK eppenage. Kestrel rudders tend to 'hunt' a bit. I have the larger
modified rudder. The Kestrel can't match the outstanding glide of the
LAK though, especially above 90kts, or when ballasted.

Kestels hold very little water and it's not recommended to put any
water in them at all if not refitted with bags, since the single glass
layer internal layup leaked in a few and the balsa core doesn't like
water.


Bruce Greef wrote:
Hi all

If anyone has an electronic version of the T59D manual I would much appreciate a
copy. I do have a paper version came with serial #1771. Unfortunately the
quality is poor and many of the diagrams are illegible (high acid paper + 30 years)

As an aside - I have the standard question - what is the real/realistic max L/D
of this beast.


For what it is worth I attempted to soar with the owner in the Kestrel, and me
in my Std Cirrus. Cirrus in club racing trim, with mylar gap seals, polished
surfaces and every possible gap sealed, but no ballast. Wayne brushed the worst
of the dust and mud drops (from the swallows in the hangar) off the top surfaces
on the Kestrel. No gap seals at all - not even tape...
Unfortunately this handicap was not enough to allow us to fly even remotely
together... The book says 1:44 - but I am not clear if that is for the 17m
version. It certainly appeared to be better to me - my Cirrus manages ~1:36 and
I was simply unable to stay in touch with the Kestrel. At 140 km/h, after 17km
for me he was at 24km, with the same height loss - (At 30km he was at 60km,
although he had lost 1,500" relative to the Cirrus at this point, due to me
thermalling so the comparison fails)

Simple extrapolation of the figures suggest 1:53 which is unlikely. Just
wondering what the number is.

I know a fair difference is probably because of better pilot and conditions, but
in this case we were flying very close together. The only part where I stayed
even remotely close was the 200 kph final glide - it looks like the longer wings
give greater drag here and the Kestrel was less "ahead" of the Cirrus after a
20km dash than the cruise experience would have indicated. He got there a lot
faster pulling out ~3km but with similar height loss...

She may no longer be competitive in any current racing class, but the Kestrel is
a serious XC machine. So any information on real world performance?

I will add if this would be mostly thermal to thermal flying. If you
were streeting along, you might have a better chance of staying with
the Kestrel. At high speed, if the Kestrel wasn't well sealed, it has
plenty of places to leak from around the split canopy, the flaperons,
and the tail.

Frank

Frank Whiteley wrote:
1/44 for the 19, and 1/43 for the 17 are the published numbers.

For the US Sports class the K19 is handicapped at 0.859 at 993lbs (dry
with pilot), K17 at 0.910 at 838lbs, and interestingly a LAK-12 at
0.865 at 1059lbs. All have the same Wortmann airfoils on the inner
and outer spans, though the K19 is generously filleted at the root.
The LAK inner panels are only flaps, whereas at least the Kestrel 19
has full span flaperons, though the inner panels only deflect half as
much as the outer panels. It's more elegant in control harmony than
the LAK. Well sealed, a series 1-3 K19 will thermal quite comfortably
down to 38kts in +2, though many prefer a notch at +1.5. The LAK
thermals nicely down around 40kts in +2 or T. A series 4 K19, is
heavier with ~250lb higher gross and one owner told me he liked
thermaling about 50kts in his series 4. I encountered him one day in
the UK and couldn't understand why he seemed to be thermaling so fast,
so we chatted about it later. Not sure how many series 4 were ever
built. I think the difference in being comfortable thermaling in +2 in
my Kestrel may be due to the addition of the mylar seals top and
bottom. Without them, I think pilots prefer in the +1.5 notch.

Kestrels run very well when conditions warrant 70kt+ cruise and will
run away from your Std Cirrus in short order, especially into wind. A
well prepared even more so. On a weak day, you might stick for a while
as they are heavy and don't climb as well in weak conditions. I could
readily out run, but not out climb my old 19m Open Cirrus in the
Kestrel 19. Shifting flaps in a Kestrel is like shifting gears in a
sports car, lots of fun and noticeably effective. Seldom need to
re-trim, as it's the same trigger trim setup as a Libelle it's quite
easy. Despite, not having mylar, that Kestrel 19 probably does have
the original internal seals. Like the control harmony, shifting flaps
in the LAK is not quite as well defined and there's more re-trimming
involved. The T-tail mass of the Kestrel is quite a bit more than the
LAK eppenage. Kestrel rudders tend to 'hunt' a bit. I have the larger
modified rudder. The Kestrel can't match the outstanding glide of the
LAK though, especially above 90kts, or when ballasted.

Kestels hold very little water and it's not recommended to put any
water in them at all if not refitted with bags, since the single glass
layer internal layup leaked in a few and the balsa core doesn't like
water.


Bruce Greef wrote:
Hi all

If anyone has an electronic version of the T59D manual I would much appreciate a
copy. I do have a paper version came with serial #1771. Unfortunately the
quality is poor and many of the diagrams are illegible (high acid paper + 30 years)

As an aside - I have the standard question - what is the real/realistic max L/D
of this beast.


For what it is worth I attempted to soar with the owner in the Kestrel, and me
in my Std Cirrus. Cirrus in club racing trim, with mylar gap seals, polished
surfaces and every possible gap sealed, but no ballast. Wayne brushed the worst
of the dust and mud drops (from the swallows in the hangar) off the top surfaces
on the Kestrel. No gap seals at all - not even tape...
Unfortunately this handicap was not enough to allow us to fly even remotely
together... The book says 1:44 - but I am not clear if that is for the 17m
version. It certainly appeared to be better to me - my Cirrus manages ~1:36 and
I was simply unable to stay in touch with the Kestrel. At 140 km/h, after 17km
for me he was at 24km, with the same height loss - (At 30km he was at 60km,
although he had lost 1,500" relative to the Cirrus at this point, due to me
thermalling so the comparison fails)

Simple extrapolation of the figures suggest 1:53 which is unlikely. Just
wondering what the number is.

I know a fair difference is probably because of better pilot and conditions, but
in this case we were flying very close together. The only part where I stayed
even remotely close was the 200 kph final glide - it looks like the longer wings
give greater drag here and the Kestrel was less "ahead" of the Cirrus after a
20km dash than the cruise experience would have indicated. He got there a lot
faster pulling out ~3km but with similar height loss...

She may no longer be competitive in any current racing class, but the Kestrel is
a serious XC machine. So any information on real world performance?

Thanks Frank

for what it is worth she is serial number 1771. As far as I know this makes her
a T59D Series two.


As for the gap seals. This glider was recently professionally refurbished, and
is immaculate, apart from the layer of dust. There is presumably room for some
canopy and control rod sealing as she makes a characteristic, and loud howl at
just about any speed. I can't say whether this is heard from the cockpit, as I
have never flown her.

The conditions were strong thermals and into a very light headwind, but she
certainly ran away from my Std Cirrus. I was unable to out climb the Kestrel,
but conversely was able to hold my own. This achieved by doing the Cirrus party
trick of digging the wing in and making really tight turns in the core of the
thermal. Whether the Kestrel is unable to turn as tight, or the pilot was being
kind I don't know.

He has commented that you don't generally change the stick trim, just change the
flaps to change speed.