Kestrel 19 Questions

Sorry for posting aircraft-specific questions in here, but I haven't
received any responses from my queries in the Kestrel401 forum.

I recently bought a Slingsby T59D Kestrel 19. Love the ship Okay,
it's big and heavy, but so am I.

I need to get my hands on the Addenda for the POH, specifically
numbers 3, 4, 5, 6 and 8. Does anyone have a copy that they could
photocopy and send to me (I'll pay costs), or scan and e-mail?
Slingsby wants 70 GBP for this -- am I naive in thinking that's rather
costly?

Secondly, I've read on-line that there is a modification to the
spoilers to add a second panel and (hopefully) increase their dismal
effectiveness. Does anyone have a copy of the information on how to
do this, and willing to share? Is the modification approved? How
effective is the new setup? The directions used to be posted at
gliderpilot.net, but it seems that the files section has not returned
up after the unfortunate problems earlier this year.

Thirdly, my weight and balance is "odd", to say the least. I've only
got a 9-lb range to stay within CoG limits, which seems fairly narrow
(same was true for the factory-delivered W&B). Granted, my previous
experience was with club ships (1-34, L-33, G-102) which had a wide
range. The plane has also flown 40 lbs under min. pilot weight (we
goofed) but flew beautifully -- certainly not like an aircraft beyond
aft CoG. Is this typical for the Kestrel?

TIA,
John

wrote:

Snip...

Thirdly, my weight and balance is "odd", to say the least. I've only
got a 9-lb range to stay within CoG limits, which seems fairly narrow
(same was true for the factory-delivered W&B). Granted, my previous
experience was with club ships (1-34, L-33, G-102) which had a wide
range. The plane has also flown 40 lbs under min. pilot weight (we
goofed) but flew beautifully -- certainly not like an aircraft beyond
aft CoG. Is this typical for the Kestrel?

TIA,
John

I don't normally jump in on things as this - having never actually seen
a Kestrel 19 except in magazines - but conceptually something's not
right here as-stated.

Assuming a 36" root chord and an allowable CG range of (e.g.) 25%-40% of
root chord, you'd have an allowable range of CG movement of 5.4" and
there's no way a 9-lb increment will move you from outside front to
outside rear of such a range on a man-sized glider of Kestrel mass.

That noted, "Rotsa Ruck!" solving your mystery.

Regards,
Bob W.

T59D - Heavy on the ground but a pleasure in the air.

Some comments -
1] Why would you want extra airbrake?
There are two versions of the landing flaps, but from my experience the landing flaps are effective at establishing
steep descents. Just be aware the roll rate is a lot lower in landing flap.
The airbrakes are pretty weak on their own.
The drogue chute really brings you down fast - but make sure you have excess speed.
Throw airbrake, landing flap and the chute out and "if you can see it over the glare shield you cant get there" applies.

2] The one I fly does not have a tiny CG range, the allowable cockpit weight ranges from 79kg to 110kg. So - 9 pounds
where? - on the tail 9 pounds is quite a lot.

3] The anti balance tab on the elevator (Mod 9) allows aft CG limit to be 15.83 inches.

As an aside - You know who your real friends are the second time you ask for help rigging the T59D - Especially when
someone has lost the tool to pull the wings together...

If you manage to get any manual pages I would appreciate - the condition of 1771s is so poor they are virtually
unreadable. I sent you a copy of the BGA data sheet with the basic information directly.

My guess on real L/D is at least as good as the claimed 1:44.


wrote:
Sorry for posting aircraft-specific questions in here, but I haven't
received any responses from my queries in the Kestrel401 forum.

I recently bought a Slingsby T59D Kestrel 19. Love the ship Okay,
it's big and heavy, but so am I.

I need to get my hands on the Addenda for the POH, specifically
numbers 3, 4, 5, 6 and 8. Does anyone have a copy that they could
photocopy and send to me (I'll pay costs), or scan and e-mail?
Slingsby wants 70 GBP for this -- am I naive in thinking that's rather
costly?

Secondly, I've read on-line that there is a modification to the
spoilers to add a second panel and (hopefully) increase their dismal
effectiveness. Does anyone have a copy of the information on how to
do this, and willing to share? Is the modification approved? How
effective is the new setup? The directions used to be posted at
gliderpilot.net, but it seems that the files section has not returned
up after the unfortunate problems earlier this year.

Thirdly, my weight and balance is "odd", to say the least. I've only
got a 9-lb range to stay within CoG limits, which seems fairly narrow
(same was true for the factory-delivered W&B). Granted, my previous
experience was with club ships (1-34, L-33, G-102) which had a wide
range. The plane has also flown 40 lbs under min. pilot weight (we
goofed) but flew beautifully -- certainly not like an aircraft beyond
aft CoG. Is this typical for the Kestrel?

TIA,
John

Assuming a 36" root chord and an allowable CG range of (e.g.) 25%-40% of
root chord, you'd have an allowable range of CG movement of 5.4" and
there's no way a 9-lb increment will move you from outside front to
outside rear of such a range on a man-sized glider of Kestrel mass.

I'd agree with Bob, where'd the 9# come from? If the ship has been
repaired or re-finished, it could have gained significant tail weight
and this would require much more cockpit weight to stay within
published CG range. Guess that would/could bring the minimum cockpit
load up to within 9# of the maximum cockpit load? There is also a
maximum weight for non-lifting surfaces (fuselage + pilot) which could
be the limiting factor on the high side. Guess it isn't a deal breaker
as long as you hit the 9# range. I remember a Nimbus-3 that was in
about the same situation.
JJ

On Oct 29, 8:55*am, JJ Sinclair wrote:

I'd agree with Bob, where'd the 9# come from? If the ship has been
repaired or re-finished, it could have gained significant tail weight
and this would require much more cockpit weight to stay within
published CG range. Guess that would/could bring the minimum cockpit

I think I'm running into the max weight consideration. I need to get
my calculation sheet and figure out the max pilot without considering
gross dry (on the weekend).

The factory W&B and placards indicate a pilot weight range from 221 to
229 lbs, with a ship empty weight of 731 lbs. The max landing weight
was 960 lbs, so the 229 pilot would hit gross dry weight. The W&B
calculations are designed to have min pilot weight giving full aft
CoG.

I removed 10 lbs of lead from the nose bulkhead -- had a Slingsby
stamp on it, so I guess it was installed at the factory. The tail has
been repaired, the rudder enlarged, and a repair to a wingtip. New
empty weight is 737 lbs -- which indicates 16lbs added for the various
repairs. Slingsby also upped the gross dry weight to 990lbs. The new
figures are not out of line from the factory, given the change of
weight locations (10 lbs out of nose, 15 added to tail).

My calculations give a minimum pilot weight of 243 lbs, and simple
math puts the max pilot at 253. I'll fully calculate the range when I
get to my papers.

However, the ship flew quite well with a 200 lb pilot -- he said it
handled beautifully. He should have been quite aft of CoG, but it
didn't handle like it was too aft... so what gives?

As an aside, why would the designers allow for only 80 lbs of water to
be carried? Hardly seems worth the effort (I can only carry 50 lbs).
I know one pilot wrote a while ago about modifying his Kestrel to
carry something like 250 lbs... what would that do to the legal status
of the aircraft when flying loaded? Insurance factors when trying to
land (over)loaded due to a rope break? Just wondering...

Thanks all,
John

On Oct 29, 3:35*pm, wrote:

My calculations give a minimum pilot weight of 243 lbs, and simple
math puts the max pilot at 253. *I'll fully calculate the range when I
get to my papers.

Found some figures.
CoG range is 11.5 - 14.76" aft of datum (leading edge at root)
Main wheel weight, 633 # at 2.5" aft
Tail wheel weight, 104# at 165.5" aft
Pilot sits at 17.2" forward

Plug it into the formula, gives min pilot of 247.7# and a max pilot of
359.5# (but I'm limited to 253# due to gross dry weight). Of course,
I might be having an off day with the calculator (or messing up my
physics); my memory keeps nagging that it's 243 minimum from the W&B
pictures and formulae.

My test pilot at 200# gives a CoG of 16.39" aft... 1.63" beyond the
max aft allowable. Yet, the ship flew beautifully.

Very odd, I think.

Regards,
John

John,
Recommend you get a new W&B with you in the cockpit. Some ships fly
quite well behind the aft limit (Nimbus-3), but the concern would be;
How well do they recover from a spin with an aft GC? Your removing
factory weight from the nose and known added aft weight (rudder) would
leave me nervous.
JJ

wrote:
On Oct 29, 3:35�pm, wrote:

My calculations give a minimum pilot weight of 243 lbs, and simple
math puts the max pilot at 253. �I'll fully calculate the range when I
get to my papers.

Found some figures.
CoG range is 11.5 - 14.76" aft of datum (leading edge at root)
Main wheel weight, 633 # at 2.5" aft
Tail wheel weight, 104# at 165.5" aft
Pilot sits at 17.2" forward

Plug it into the formula, gives min pilot of 247.7# and a max pilot of
359.5# (but I'm limited to 253# due to gross dry weight). Of course,
I might be having an off day with the calculator (or messing up my
physics); my memory keeps nagging that it's 243 minimum from the W&B
pictures and formulae.

My test pilot at 200# gives a CoG of 16.39" aft... 1.63" beyond the
max aft allowable. Yet, the ship flew beautifully.

Very odd, I think.

Regards,
John

At 20:42 29 October 2008, JJ Sinclair wrote:
John,
Recommend you get a new W&B with you in the cockpit. Some ships fly
quite well behind the aft limit (Nimbus-3), but the concern would be;
How well do they recover from a spin with an aft GC? Your removing
factory weight from the nose and known added aft weight (rudder) would
leave me nervous.
JJ

wrote:
On Oct 29, 3:35=EF=BF=BDpm, wrote:

My calculations give a minimum pilot weight of 243 lbs, and simple
math puts the max pilot at 253. =EF=BF=BDI'll fully calculate the
range=
when I
get to my papers.

Found some figures.
CoG range is 11.5 - 14.76" aft of datum (leading edge at root)
Main wheel weight, 633 # at 2.5" aft
Tail wheel weight, 104# at 165.5" aft
Pilot sits at 17.2" forward

Plug it into the formula, gives min pilot of 247.7# and a max pilot of
359.5# (but I'm limited to 253# due to gross dry weight). Of course,
I might be having an off day with the calculator (or messing up my
physics); my memory keeps nagging that it's 243 minimum from the W&B
pictures and formulae.

My test pilot at 200# gives a CoG of 16.39" aft... 1.63" beyond the
max aft allowable. Yet, the ship flew beautifully.

Very odd, I think.

Regards,
John

John are you weighing the glider correctly?
eg tail boom should be at a certain angle, from POH
are you also measuring the distances carefully using the tail boom at the
correct angle and also using a plumb bob.

Errors in these figures will give a marked difference

jon

At 20:42 29 October 2008, JJ Sinclair wrote:
John,
Recommend you get a new W&B with you in the cockpit. Some ships fly
quite well behind the aft limit (Nimbus-3), but the concern would be;
How well do they recover from a spin with an aft GC? Your removing
factory weight from the nose and known added aft weight (rudder) would
leave me nervous.
JJ

wrote:
On Oct 29, 3:35=EF=BF=BDpm, wrote:

My calculations give a minimum pilot weight of 243 lbs, and simple
math puts the max pilot at 253. =EF=BF=BDI'll fully calculate the
range=
when I
get to my papers.

Found some figures.
CoG range is 11.5 - 14.76" aft of datum (leading edge at root)
Main wheel weight, 633 # at 2.5" aft
Tail wheel weight, 104# at 165.5" aft
Pilot sits at 17.2" forward

Plug it into the formula, gives min pilot of 247.7# and a max pilot of
359.5# (but I'm limited to 253# due to gross dry weight). Of course,
I might be having an off day with the calculator (or messing up my
physics); my memory keeps nagging that it's 243 minimum from the W&B
pictures and formulae.

My test pilot at 200# gives a CoG of 16.39" aft... 1.63" beyond the
max aft allowable. Yet, the ship flew beautifully.

Very odd, I think.

Regards,
John

John are you weighing the glider correctly?
eg tail boom should be at a certain angle, from POH
are you also measuring the distances carefully using the tail boom at the
correct angle and also using a plumb bob.

Errors in these figures will give a marked difference

jon

I have come across an ASW 20 which was quite limited by max landing weight,
mainly due to assorted optional equipment

as 15lbs seems a lot for a fuz a repair

The larger rudder may well have quite a bit of mass balance lead on the
leading edge, so it would be worth checking the rudder mass balance, and
considering if it could be stripped and refinished lighter to reduce the
mass balance, a few oz of finish could equall a pound of mass balance

if the previous owners "optimised " the C of G there may be a lump of
lead behind the rudder, in the tail wheel box, at the top of the fin, or
heavy tailwheel.

so it may well be worth taking the rudder off

oxgen bottle?

although max dry(landing)wt is lower down the priority list than any
weight limits that are significant in flight, if you realy dont need it,
might be worth stripping out the waterballast kit

if you look on the BGA web site, gliding.co.uk under
airworthiness/datasheets, there might be some useful hints there.

Pete


At 21:00 29 October 2008, Jon Marshall wrote:
At 20:42 29 October 2008, JJ Sinclair wrote:
John,
Recommend you get a new W&B with you in the cockpit. Some ships fly
quite well behind the aft limit (Nimbus-3), but the concern would be;
How well do they recover from a spin with an aft GC? Your removing
factory weight from the nose and known added aft weight (rudder) would
leave me nervous.
JJ

wrote:
On Oct 29, 3:35=EF=BF=BDpm, wrote:

My calculations give a minimum pilot weight of 243 lbs, and simple
math puts the max pilot at 253. =EF=BF=BDI'll fully calculate the
range=
when I
get to my papers.

Found some figures.
CoG range is 11.5 - 14.76" aft of datum (leading edge at root)
Main wheel weight, 633 # at 2.5" aft
Tail wheel weight, 104# at 165.5" aft
Pilot sits at 17.2" forward

Plug it into the formula, gives min pilot of 247.7# and a max pilot
of
359.5# (but I'm limited to 253# due to gross dry weight). Of
course,
I might be having an off day with the calculator (or messing up my
physics); my memory keeps nagging that it's 243 minimum from the W&B
pictures and formulae.

My test pilot at 200# gives a CoG of 16.39" aft... 1.63" beyond the
max aft allowable. Yet, the ship flew beautifully.

Very odd, I think.

Regards,
John

John are you weighing the glider correctly?
eg tail boom should be at a certain angle, from POH
are you also measuring the distances carefully using the tail boom at
the
correct angle and also using a plumb bob.

Errors in these figures will give a marked difference

jon