Heavy pilot - what glider to opt for?

How does the glider fly if a pilot is over the maximum allowable weight? Not slow I bet.

"Divide the stone by 14, only people with the same passport I have use that measure, to get pounds"

I think you meant to type "multiply by 14 to get pounds" :-)

My club has a retractable gear Twin Astir which has the payload to take a 245 lb. pilot in both seats simultaneously. You need room - easy to judge if you can get a look at a glider and sit in it, type certificate pilot load of at least 245 lbs. and the hardest part - actual payload capacity depending upon the remaining payload of the glider at its actual current weight (given equipment and any weight increase brought about by repairs) and the center of gravity considerations.

Any glider you get seriously interested in, make absolutely sure that it has had a recent weight and balance performed performed correctly. That isn't always done. We have a single Astir where the weight and balance in the books done for the export C of A when purchased was out by about 80 pounds. We found out when the glider was re-weighed after the installation of all the control mass balance weight under an AD. Strangely, the old weight and balance said the glider was HEAVIER than it really was!

Har!
At least someone's paying attention, evidently not me.
Jim

On Thursday, October 31, 2013 12:03:46 PM UTC-7, wrote:

I think you meant to type "multiply by 14 to get pounds" :-)

I'm an early solo pilot and I am also looking around for a first glider and leaning towards an Astir G102 CS.
I'm also 6'4" tall although my mass is a little lower (95kg/15 stone).

The problem is that not every one has the same proportions. For example I am long in the legs and have a shorter upper torso.
I did all my training in a G103 and I did not fit well at all. The air brake would pop open if I used full right rudder because the lever was jammed up against my left knee. Other students my height were longer in the torso and had no problems fitting in the G103.

In terms of the glider I can say that the club G102 Astir CS I fly has a large roomy cockpit and much more legroom than the G103. Finding the right type of parachute is an important factor too as it has a vast effect on head and leg room.
The maximum cockpit load in the G102's is 110kg and you're going to be on the limit without a parachute and a bit over with one.
I doubt that 8kg over the limit with a chute would have any major effect on handling but one would need to take insurance and liability into account if you do decide to go that route.
Take note that the Astir CS-77 has a flatter canopy which makes the cockpit much more cramped and adds zero performance benefit from what I've read.
In terms of handling the Astir is nice and docile on low hour pilots yet has enough performance for decent cross country flying. I haven't managed to scare myself with one yet.
In terms of cost I don't think you're going to find anything much cheaper in the glass range than the G102 and spares appear to be plentiful world wide.

I'd love to purchase an ASW-20 as my first ship (after I have a few more hours under my belt) but they sell for around four times that of a G102 and only add around 6 points to the L/D from what I can see.

On Friday, November 1, 2013 4:45:35 AM UTC-4, Surge wrote:

the Astir CS-77 has a flatter canopy which makes the cockpit much more cramped

Has a glider manufacturer ever offered an overblown canopy to add a few inches of head height?

And what about offering a slightly deeper seat pan as an option? Windward Performance offers the deeper seat pan option.

I wonder what percentage of modern-sized people are just too big for a sailplane.

On Thursday, October 31, 2013 9:03:26 AM UTC-5, son_of_flubber wrote:
How does the glider fly if a pilot is over the maximum allowable weight? Not slow I bet.

With racing glass it is more of a CG/trim issue, since practically it mainly limits how much water you can carry before exceeding your max gross weight, and how low you can get your wingloading dry. A heavy pilot also moves the CG forward, which can have significant negative effect on climbing performance.

I pretty much max out my useful load in my LS6, and had to add appropriate weight aft to keep the CG somewhere useful; careful W&B accomplished of course to stay legal (barely). Before adjusting the CG my climb rate suffered due to having to hold too much aft stick, now I climb just fine, thankyou. My min w/l is around 8 psf, which in an LS6 is actually pretty nice - especially in no-ballast-allowed races!

But there is the subtle problem of the total weight of non-lifting parts - because weight in the cockpit is not the same as weight in the wings...so one has to be careful and watch the numbers per the flight manual.

Real world effect is probably slightly lower G limits due to greater stress at the wing roots; any aero engineers feel free to jump in if I'm wrong!

Kirk
66

On Friday, November 1, 2013 6:44:09 AM UTC-7, kirk.stant wrote:
On Thursday, October 31, 2013 9:03:26 AM UTC-5, son_of_flubber wrote:

How does the glider fly if a pilot is over the maximum allowable weight? Not slow I bet.



With racing glass it is more of a CG/trim issue, since practically it mainly limits how much water you can carry before exceeding your max gross weight, and how low you can get your wingloading dry. A heavy pilot also moves the CG forward, which can have significant negative effect on climbing performance.



I pretty much max out my useful load in my LS6, and had to add appropriate weight aft to keep the CG somewhere useful; careful W&B accomplished of course to stay legal (barely). Before adjusting the CG my climb rate suffered due to having to hold too much aft stick, now I climb just fine, thankyou. My min w/l is around 8 psf, which in an LS6 is actually pretty nice - especially in no-ballast-allowed races!



But there is the subtle problem of the total weight of non-lifting parts - because weight in the cockpit is not the same as weight in the wings...so one has to be careful and watch the numbers per the flight manual.



Real world effect is probably slightly lower G limits due to greater stress at the wing roots; any aero engineers feel free to jump in if I'm wrong!



Kirk

66

Kirk, I don't think you can trade cockpit load for water ballast load since cockpit load is part of nonflying parts and ballast goes in the wing so there ought to be a big difference in the loads on wing-fuselage fittings and main spar bending loads - I don't think that is a straight weight/g-load linear relationship. I am less clear on what you are allowed to do for Experimental aircraft, but I don't think you can just re-calculate the bending moments for a certified airplane and go fly with a different flight envelope..

Ripping the wings off could ruin your whole day.

9B

Cheers for your suggestions!

On Friday, November 1, 2013 9:56:15 AM UTC-5, wrote:

Kirk, I don't think you can trade cockpit load for water ballast load since cockpit load is part of nonflying parts and ballast goes in the wing so there ought to be a big difference in the loads on wing-fuselage fittings and main spar bending loads - I don't think that is a straight weight/g-load linear relationship. I am less clear on what you are allowed to do for Experimental aircraft, but I don't think you can just re-calculate the bending moments for a certified airplane and go fly with a different flight envelope.

Correct - that's why I caveat that a careful W&B is necessary! My point is that at least in my LS6, you could not have a max weight pilot and full water without exceeding the gross wt limit; so in effect some of the pilot wt is taken out of the allowable ballast wt.

As always, RTFM.

Cheers,

Kirk

One source of confusion on cockpit loads is that the airworthiness
requirement for certification under JAR 22 was (and I think still is under
the current regulations) that, with basic instrumentation, the minimum
cockpit load must be not more than 70 Kg/154 lbs and the maximum not less
than 110 Kg/ 242 lbs. Most gliders, if weighed and weight and balance
calculations done, will have limits wider than this, in some cases much
wider. Some time back, the major German manufacturers developed the
practice of sending new gliders out of the factory placarded with the
70/110 kg limits, checking their weight and balance and calculating
cockpit loads on delivery usually enabled the re-placarding of wider
limits. This was a common practice in the UK, not sure if it was much done
in the USA.

At 22:47 03 November 2013, kirk.stant wrote:
On Friday, November 1, 2013 9:56:15 AM UTC-5,
wrote:

Kirk, I don't think you can trade cockpit load for water ballast load
sin=
ce cockpit load is part of nonflying parts and ballast goes in the wing
so
=
there ought to be a big difference in the loads on wing-fuselage fittings
a=
nd main spar bending loads - I don't think that is a straight
weight/g-load=
linear relationship. I am less clear on what you are allowed to do for
Exp=
erimental aircraft, but I don't think you can just re-calculate the
bending=
moments for a certified airplane and go fly with a different flight
envelo=
pe.

Correct - that's why I caveat that a careful W&B is necessary! My point
is=
that at least in my LS6, you could not have a max weight pilot and full
wa=
ter without exceeding the gross wt limit; so in effect some of the pilot
wt=
is taken out of the allowable ballast wt.

As always, RTFM.

Cheers,

Kirk