Glider Wheel Brakes

On Fri, 9 May 2008 18:15:51 -0700 (PDT),
wrote:

I know, I know. BTDT. Has anyone purchased a NEW sailplane lately,
and been happy with the wheel brake? The ONLY glider I've ever flown
with a decent (not great, but decent) wheel brake is the LVVSA's G103
Twin Astir. For me, a GREAT brake will REQUIRE moderation on my part
to keep from grinding the nose. I'm used to relatively modern
motorcycles, that will lock the front wheel with 2 or 3 fingers. I
would vastly rather scrape my nose, than hit the barbed wire at the
far end of a landout.

My partners and I used to have an Astir-CS. A careful brake adjustment
would buy you one, maybe two, firm stops, and the next stop would get
more help from the tailskid than from the brake.

We tried grooving the brake shoes which our mechanic recommended, but
that had no effect. The real problem was in the linkage. It was
actuated by a motorcycle squeeze grip on the stick, and there just
wasn't enough travel available. If the handle moved more than an inch
before the shoe made contact, the rest of its travel would be used up
in stretching the cable, and the handle would hit the stick grip
before any real force got to the shoes.

So we decided to try replacing the cable with something stiffer. An
extensive parts search disclosed that the existing cable was precisely
identical to a Bultaco clutch cable...we were trying to stop a
600-pound sailplane with a cable meant to work the CLUTCH on a
200-pound motorcycle. We eventually found something that worked a bit
better, but still had to adjust pretty frequently.

rj

On May 10, 11:19*am, Ralph Jones wrote:
On Fri, 9 May 2008 18:15:51 -0700 (PDT),
wrote:

I know, I know. *BTDT. *Has anyone purchased a NEW sailplane lately,
and been happy with the wheel brake? *The ONLY glider I've ever flown
with a decent (not great, but decent) wheel brake is the LVVSA's G103
Twin Astir. For me, a GREAT brake will REQUIRE moderation on my part
to keep from grinding the nose. *I'm used to relatively modern
motorcycles, that will lock the front wheel with 2 or 3 fingers. *I
would vastly rather scrape my nose, than hit the barbed wire at the
far end of a landout.

My partners and I used to have an Astir-CS. A careful brake adjustment
would buy you one, maybe two, firm stops, and the next stop would get
more help from the tailskid than from the brake.

We tried grooving the brake shoes which our mechanic recommended, but
that had no effect. The real problem was in the linkage. It was
actuated by a motorcycle squeeze grip on the stick, and there just
wasn't enough travel available. If the handle moved more than an inch
before the shoe made contact, the rest of its travel would be used up
in stretching the cable, and the handle would hit the stick grip
before any real force got to the shoes.

So we decided to try replacing the cable with something stiffer. An
extensive parts search disclosed that the existing cable was precisely
identical to a Bultaco clutch cable...we were trying to stop a
600-pound sailplane with a cable meant to work the CLUTCH on a
200-pound motorcycle. We eventually found something that worked a bit
better, but still had to adjust pretty frequently.

rj

Yes, I've replaced the original cable on my Speed Astir with more
substantial cable, running in a Teflon sleeved outer. Some
improvement, but lets face it, the mass of the glider and the size of
that single leading shoe brake make it stop, quite predictiably, just
as well as an early 60's Harley.