Kestrel 19 Questions

Also note that the datum is from the wing leading edge 500mm outboard from the fuselage.

Bruce

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

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.

Yes, yes and an equivalent. There's a pre-cut tool plate with the
correct angle on it; we put it on the boom spine and used a spirit
level. My AME did the W&B following the original factory methodology
and documentation. The results were not far off the factory original,
giving consideration to removing the nose weight and doing mod/repair
in the tail -- just heavier in the tail.

The previous owner actually had 30 lbs of lead in the nose: the
original 10 from the factory, plus he added 20. He flew at 186 lbs;
I'm just over 240, so I figured the balance wouldn't suffer. I'm
considering returning the 10 lbs to the nose, which should lower the
min pilot by about 15 lbs or so and shift the CoG forward a bit for
me.

15 lbs is a lot for the mod and repairs? The boom was broken in a
landing and knocked off the tail. A couple of pounds would have gone
into extending the rudder (about 3.5" wide) and mass-balancing. What
would the weight be to repair a wing run over by one of those short-
winged 15m ships? W&B was _not_ done after the repairs or the mod...
at least not that I've found a record (and I've got lots records for
the ship, dating back to importation).

Pulling out the water ballast plumbing is possible. The hoses are not
in place when I fly (that's about a pound or so). I don't know if the
Kestrel uses water bags or wing structure to hold the water (I _think_
it's just in the structure) -- I'll check in the Spring and pull any
bags, if possible.

There is an oxygen bottle, but not listed in the original W&B and I
don't fly with it. The system is very old, so if I ever need oxygen
(not in Southern Ontario), I think I'll just buy a nice, modern
system. The bottle has a mount location just aft of CoG (not much
room, elsewhere).

I've appreciated the information and advice... still learning lots
about my ship. Anyone have the Addenda?

Regards,
John

On Thu, 30 Oct 2008 07:16:52 -0700, johnbrake wrote:


Pulling out the water ballast plumbing is possible. The hoses are not
in place when I fly (that's about a pound or so). I don't know if the
Kestrel uses water bags or wing structure to hold the water (I _think_
it's just in the structure) -- I'll check in the Spring and pull any
bags, if possible.

Its bags. I know that because at least one H.201 Libelle has been fitted
with a Kestrel water ballast system: the original H.201 did not carry
water. That became an option for the H.201b series.

There is an oxygen bottle, but not listed in the original W&B and I
don't fly with it. The system is very old, so if I ever need oxygen
(not in Southern Ontario), I think I'll just buy a nice, modern system.
The bottle has a mount location just aft of CoG (not much room,
elsewhere).

A Kevlar MH system weighs under 3 kg, so if it installs in the same place
as the Libelle (in a tube under the turtledeck behind the cockpit) its
impact on CG should be minimal.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Oct 30, 8:16*am, wrote:
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.

Yes, yes and an equivalent. *There's a pre-cut tool plate with the
correct angle on it; we put it on the boom spine and used a spirit
level. *My AME did the W&B following the original factory methodology
and documentation. *The results were not far off the factory original,
giving consideration to removing the nose weight and doing mod/repair
in the tail -- just heavier in the tail.

The previous owner actually had 30 lbs of lead in the nose: the
original 10 from the factory, plus he added 20. *He flew at 186 lbs;
I'm just over 240, so I figured the balance wouldn't suffer. *I'm
considering returning the 10 lbs to the nose, which should lower the
min pilot by about 15 lbs or so and shift the CoG forward a bit for
me.

15 lbs is a lot for the mod and repairs? *The boom was broken in a
landing and knocked off the tail. *A couple of pounds would have gone
into extending the rudder (about 3.5" wide) and mass-balancing. *What
would the weight be to repair a wing run over by one of those short-
winged 15m ships? *W&B was _not_ done after the repairs or the mod...
at least not that I've found a record (and I've got lots records for
the ship, dating back to importation).

Pulling out the water ballast plumbing is possible. *The hoses are not
in place when I fly (that's about a pound or so). *I don't know if the
Kestrel uses water bags or wing structure to hold the water (I _think_
it's just in the structure) -- I'll check in the Spring and pull any
bags, if possible.

There is an oxygen bottle, but not listed in the original W&B and I
don't fly with it. *The system is very old, so if I ever need oxygen
(not in Southern Ontario), I think I'll just buy a nice, modern
system. *The bottle has a mount location just aft of CoG (not much
room, elsewhere).

I've appreciated the information and advice... still learning lots
about my ship. *Anyone have the Addenda?

Regards,
John

http://web.archive.org/web/200003020...o.uk/cots6.htm
Note this DG300. It weighed within 10 ounces of the original when
repaired. It was also repaired by the pilot that flew it through the
wires.