Empty/Gross weight Vs. Max. Pilot weight

Hi All!
I'm confused by the weight restrictions on most gliders.
As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs? It seems to me like the
difference between the empty & gross weights could be made up of any
combination of pilot, equipment & ballast as long as the gross weight is not
exceeded & the C.G. remains within limits. What am I not understanding here?

As any of you know who have read my numerous recent questions to this group I
am a new and BIG pilot trying to figure out which ships will work for me &
learn a little more about this endeavor. I could weigh as much as 250lbs fully
equipped in the winter. That appears to exceed the limits of almost all
gliders.

Again the generous information that I've gotten from you all is just great!

Thanks!
David Roth

maybe max weight of none lifting parts

Flyhighdave wrote:

Hi All!
I'm confused by the weight restrictions on most gliders.
As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs? It seems to me like the
difference between the empty & gross weights could be made up of any
combination of pilot, equipment & ballast as long as the gross weight is not
exceeded & the C.G. remains within limits. What am I not understanding here?

The difference is where the weight is carried:

- in the wings, it reduces the load on the wing spars, especially at the
root. That's why it's carried there.
- in the cockpit, it increases the load on the wig spares, especially at
the root. This is why there is a "non-lifting" parts (basically, the
fuselage) load limit, in addition to an overall limit.

The actual limit may also be set by things like seat and belt attachment
strength, not just the wing strength. You don't know, unless the
designer tells you.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

See JAR 22
http://www.jaa.nl/section1/jars/445499.pdf
Sections 22.25 and 22.785
for details.

110kg is minimum maximum under the above, but also an upper limit in many
cases. Older sailplanes built under OSTIV may have all a max weight of
non-flying parts that allows 250lb+ pilot weights and a safe CG range far
above that, like 350lbs.

Frank Whiteley

"Flyhighdave" wrote in message
...
Hi All!
I'm confused by the weight restrictions on most gliders.
As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs? It seems to me
like the
difference between the empty & gross weights could be made up of any
combination of pilot, equipment & ballast as long as the gross weight is
not
exceeded & the C.G. remains within limits. What am I not understanding
here?

As any of you know who have read my numerous recent questions to this
group I
am a new and BIG pilot trying to figure out which ships will work for me &
learn a little more about this endeavor. I could weigh as much as 250lbs
fully
equipped in the winter. That appears to exceed the limits of almost all
gliders.

Again the generous information that I've gotten from you all is just
great!

Thanks!
David Roth

Dear David,
the reason for the max pilot weight of 110 kg is rather simple: The (old)
European certification specifications for gliders, JAR22,
request, that the center of gravity stays within its limits at pilot weights
from 70 kg to 110 kg with parachute (!!) without
ballast, and that at least a pilot of 110 kg must be carried (see
JAR22.23-22.25). For a two seater, the value is 180 kg. So other
calculations, e.g. seat strength, belt fixpoints and so on are based on this
minimum value for the max. pilot weight of 110 kg, and
this 110 kg are printed in the glider specs. This has nothing to do with the
max. weight of 'not lifting parts' or with the payload.
So for pilots above 110 kg, it will not be easy to find a glider, which they
can fly legally.
Anyhow, you should contact the manufacturer of your glider. It might well be
he knows a solution.
Best regards
Walter

Why is pilot weight restricted?.... because that is the weight limit it was
certified to.

BT

"Flyhighdave" wrote in message
...
Hi All!
I'm confused by the weight restrictions on most gliders.
As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs? It seems to me
like the
difference between the empty & gross weights could be made up of any
combination of pilot, equipment & ballast as long as the gross weight is
not
exceeded & the C.G. remains within limits. What am I not understanding
here?

As any of you know who have read my numerous recent questions to this
group I
am a new and BIG pilot trying to figure out which ships will work for me &
learn a little more about this endeavor. I could weigh as much as 250lbs
fully
equipped in the winter. That appears to exceed the limits of almost all
gliders.

Again the generous information that I've gotten from you all is just
great!

Thanks!
David Roth

In article ,
(Flyhighdave) wrote:

Hi All!
I'm confused by the weight restrictions on most gliders.
As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs? It seems to
me like the difference between the empty & gross weights could be
made up of any combination of pilot, equipment & ballast as long as
the gross weight is not exceeded & the C.G. remains within limits.
What am I not understanding here?

- max weight of non-lifting parts (think: strength of the fuselage
mountings)

- seat and seatbelt mounting point strength

- C of G out of limits, possibly meaning not enough up elevator
available at low speeds (e.g. landing round-out)


As any of you know who have read my numerous recent questions to this
group I am a new and BIG pilot trying to figure out which ships will
work for me & learn a little more about this endeavor. I could weigh
as much as 250lbs fully equipped in the winter. That appears to
exceed the limits of almost all gliders.

The day I'm 242 lbs, including parachute, will be a minor miracle.
Right now I'm 260. Several months ago, around the beginning of spring,
I was over 270. Several years ago when I was dotcommed for a while and
bicycled 30 - 50 km every day during a Chicago summer I got down to
about 250 briefly.

I've flown quite a few gliders, at quite a few places in NZ and the USA,
and no one has *ever* suggested that I shouldn't be flying their gliders
due to weight. Sometimes I've had a conversation with an engineer or
instructor and we've agreed that I'll mentally knock 5 or 10 knots off
the placarded rough air/manouvering speeds and keep the G loading down.
I do that anyway. It's probably not necessary.

Just because it's easy to do, here's a logbook dump of the types I've
flown. Not a lot of experience, I know, but more than zero...

Glider Type Flights Total PIC Avg
=============== ======= ====== ====== ===
Club Libelle 36 56:55 56:55 95
Blanik 110 46:56 27:38 26
Janus 43 36:55 30:02 52
Ka6CR 21 26:26 26:26 76
PW-5 19 20:04 20:04 63
Twin Astir 27 14:42 12:08 33
Std Libelle 9 9:32 9:32 64
Grob 103 3 3:13 3:13 64
ASK21 6 2:42 2:42 27
Ka7 16 1:52 0:14 7
ASK13 3 1:32 1:15 31
Duo Discus 1 1:07 0:00 67
Puchacz 1 1:02 0:00 62
T53 1 0:37 0:00 37
Phoebus C 1 0:33 0:33 33
Pirat 1 0:19 0:19 19

I haven't had problems with any of the above types, although I'm
probably over the placarded weight for all of them (and some, such as
the K6 and the Std Libelle are a bit of a squeeze).

People flying marginal powered aircraft are, rightly, quite a bit more
concerned about weights. Put full tanks and two big people in a Cessna
152 and it probably won't climb at *all*.

-- Bruce

Bruce,
I don't know what the insurance arrangements are in
the places you fly, but what would worry me here in
the UK is this:
Flight outside placarded limits is outside CofA.
Flight without CofA is uninsured.
Are you sure you're covered in the event of a prang?
It's an easy get-out for an insurance company faced
with a potentially big claim.
Rob

At 06:30 12 January 2004, Bruce Hoult wrote:
In article ,
(Flyhighdave) wrote:

Hi All!
I'm confused by the weight restrictions on most gliders.

As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs?
It seems to
me like the difference between the empty & gross weights
could be
made up of any combination of pilot, equipment & ballast
as long as
the gross weight is not exceeded & the C.G. remains
within limits.
What am I not understanding here?

- max weight of non-lifting parts (think: strength
of the fuselage
mountings)

- seat and seatbelt mounting point strength

- C of G out of limits, possibly meaning not enough
up elevator
available at low speeds (e.g. landing round-out)


As any of you know who have read my numerous recent
questions to this
group I am a new and BIG pilot trying to figure out
which ships will
work for me & learn a little more about this endeavor.
I could weigh
as much as 250lbs fully equipped in the winter. That
appears to
exceed the limits of almost all gliders.

The day I'm 242 lbs, including parachute, will be a
minor miracle.
Right now I'm 260. Several months ago, around the
beginning of spring,
I was over 270. Several years ago when I was dotcommed
for a while and
bicycled 30 - 50 km every day during a Chicago summer
I got down to
about 250 briefly.

I've flown quite a few gliders, at quite a few places
in NZ and the USA,
and no one has *ever* suggested that I shouldn't be
flying their gliders
due to weight. Sometimes I've had a conversation with
an engineer or
instructor and we've agreed that I'll mentally knock
5 or 10 knots off
the placarded rough air/manouvering speeds and keep
the G loading down.
I do that anyway. It's probably not necessary.

Just because it's easy to do, here's a logbook dump
of the types I've
flown. Not a lot of experience, I know, but more than
zero...

Glider Type Flights Total PIC Avg
=============== ======= ====== ====== ===
Club Libelle 36 56:55 56:55 95
Blanik 110 46:56 27:38 26
Janus 43 36:55 30:02 52
Ka6CR 21 26:26 26:26 76
PW-5 19 20:04 20:04 63
Twin Astir 27 14:42 12:08 33
Std Libelle 9 9:32 9:32 64
Grob 103 3 3:13 3:13 64
ASK21 6 2:42 2:42 27
Ka7 16 1:52 0:14 7
ASK13 3 1:32 1:15 31
Duo Discus 1 1:07 0:00 67
Puchacz 1 1:02 0:00 62
T53 1 0:37 0:00 37
Phoebus C 1 0:33 0:33 33
Pirat 1 0:19 0:19 19

I haven't had problems with any of the above types,
although I'm
probably over the placarded weight for all of them
(and some, such as
the K6 and the Std Libelle are a bit of a squeeze).

People flying marginal powered aircraft are, rightly,
quite a bit more
concerned about weights. Put full tanks and two big
people in a Cessna
152 and it probably won't climb at *all*.

-- Bruce

"Robert John" wrote in
message ...
Bruce,
I don't know what the insurance arrangements are in
the places you fly, but what would worry me here in
the UK is this:
Flight outside placarded limits is outside CofA.
Flight without CofA is uninsured.
Are you sure you're covered in the event of a prang?
It's an easy get-out for an insurance company faced
with a potentially big claim.
Rob

I believe the same would apply here in the USofA..
obvious flight over max weight limitations.. no insurance coverage..
don't forget that some of those gliders also have, max weight for non
lifting parts
you may be within the Max GW, but not the max of the non lifting parts

BT

Robert John wrote in message ...
Bruce,
I don't know what the insurance arrangements are in
the places you fly, but what would worry me here in
the UK is this:
Flight outside placarded limits is outside CofA.
Flight without CofA is uninsured.
Are you sure you're covered in the event of a prang?
It's an easy get-out for an insurance company faced
with a potentially big claim.
Rob


NTSB database is well populated with aircraft accident reports that
list flying over max certificated gross weight as a contributing, or
primary, accident cause.

Can anyone cite a single case where insurance payout was refused on
that basis.

Please note that I am NOT advocating flying over any weight limit, I
just think the "you won't be insured" argument is a bit thin.


Andy