HP series landing gear info needed

wrote:
On Sep 22, 2:54Â*pm, Brad wrote:
On Sep 22, 11:41Â*am, T8
Who needs a shock strut when you land at 30 mph?

For those involved in this discussion they should be reminded that the landing gear in question is being installed in an HP-24 which has spoilers, NOT large span landing flaps.

Wayne

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On Sep 22, 1:31*pm, "Wayne Paul " wrote:
wrote:
On Sep 22, 2:54*pm, Brad wrote:
On Sep 22, 11:41*am, T8
Who needs a shock strut when you land at 30 mph?

For those involved in this discussion they should be reminded that the landing gear in question is being installed in an HP-24 which has spoilers, NOT large span landing flaps.

Wayne

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Still, the struts on the few HP's I've helped work on are fine after
decades of use. Brad will be landing at a higher ground speed than an
'18, but I don't see how that dictates rougher landings. My glider
has a smaller mainwheel and ZERO suspension. Once or twice (maybe
more!) I've thought some suspension would be nice!
Cheers,
Jim

On Sep 22, 12:33*pm, Brad wrote:

I'm leaning more and more for a rigid strut...

I strongly recommend against. The rigid gear will apply much stronger
impulses into the structure that supports the undercarriage pivots.
The landing gear support structure is not sized for that. As others
noted, it will work fine until that landing when it doesn't, and then
it will be messy.

The Schreder oleo strut gear is about the best bang for the buck and
for the pound there is in energy storage (springiness) and shock
absorption. When properly assembled and maintained, it is trouble-free
for decades at a time. The parts are either off-the-shelf items, or
things that any decent A&P or TIG welder can fotch up in an afternoon.

As others note, there are good and bad examples in the field. On the
leaky ones I've seen, it's been because things are bent or misaligned
so that the pistons are pre-loaded against the sides of the cylinders,
causing scoring and galling. It's easy to know when its set up right;
when the system is assembled sans O-rings the pistons slide in and out
of the cylinders with no appreciable drag. Also, you must check the
condition of the restraint cable at each annual inspection for fraying
or broken strands.

Thanks, Bob K.

On Sep 22, 3:29*pm, Bob Kuykendall wrote:
On Sep 22, 12:33*pm, Brad wrote:

I'm leaning more and more for a rigid strut...

I strongly recommend against. The rigid gear will apply much stronger
impulses into the structure that supports the undercarriage pivots.
The landing gear support structure is not sized for that. As others
noted, it will work fine until that landing when it doesn't, and then
it will be messy.

The Schreder oleo strut gear is about the best bang for the buck and
for the pound there is in energy storage (springiness) and shock
absorption. When properly assembled and maintained, it is trouble-free
for decades at a time. The parts are either off-the-shelf items, or
things that any decent A&P or TIG welder can fotch up in an afternoon.

As others note, there are good and bad examples in the field. On the
leaky ones I've seen, it's been because things are bent or misaligned
so that the pistons are pre-loaded against the sides of the cylinders,
causing scoring and galling. It's easy to know when its set up right;
when the system is assembled sans O-rings the pistons slide in and out
of the cylinders with no appreciable drag. Also, you must check the
condition of the restraint cable at each annual inspection for fraying
or broken strands.

Thanks, Bob K.

Thanks all for the tip, Wayne, I'll give you a call later this
afternoon.

I just installed the landing gear and retract system in the HP-24, I
did hit the valve with 120 PSI of O2 and it is holding just fine, no
fluid in yet. I am tending to think Bob is right and I'll go ahead and
just go with the shock strut as intended, the gear was holding
pressure after I salvaged it from an HP-18 a few years ago, and that
was after the -18 sat in the trailer for a few decades............I
made the mistake of un-screwing the valve w/o bleeding it
first...............luckily my face wasn't over the valve, and the
ceiling in my shop still has a reminder of what fluid under pressure
does when it is allowed to escape!

Brad

PS..................the HP-24 is all painted
now...................anyone seeing it will be required to not look
too closely at the fuselage, that was a real bugger to sand flat.

On 9/22/2011 2:27 PM, jim wynhoff wrote:


Still, the struts on the few HP's I've helped work on are fine after
decades of use. Brad will be landing at a higher ground speed than an
'18, but I don't see how that dictates rougher landings. My glider
has a smaller mainwheel and ZERO suspension. Once or twice (maybe
more!) I've thought some suspension would be nice!

Landing in a rough field makes a pilot appreciate a suspension on the
landing gear. Landing faster in rough field makes a pilot REALLY
appreciate a suspension on the landing gear. A well done suspension can
reduce injury some crash situations, but I don't know if the gear in
question was designed to do that.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

On Sep 22, 6:29*pm, Bob Kuykendall wrote:
It's easy to know when its set up right;
when the system is assembled sans O-rings the pistons slide in and out
of the cylinders with no appreciable drag.

My ship would have failed that test. By the time I'd noticed this (I
was the third owner), the damage to the oleo cylinder was done and I
didn't really have a clue as to how about putting it right. It's
awfully hard to make holes that are in the wrong place go away so you
can start over.

-Evan Ludeman / T8

On Sep 22, 5:29*pm, Brad wrote:
On Sep 22, 3:29*pm, Bob Kuykendall wrote:









On Sep 22, 12:33*pm, Brad wrote:

I'm leaning more and more for a rigid strut...

I strongly recommend against. The rigid gear will apply much stronger
impulses into the structure that supports the undercarriage pivots.
The landing gear support structure is not sized for that. As others
noted, it will work fine until that landing when it doesn't, and then
it will be messy.

The Schreder oleo strut gear is about the best bang for the buck and
for the pound there is in energy storage (springiness) and shock
absorption. When properly assembled and maintained, it is trouble-free
for decades at a time. The parts are either off-the-shelf items, or
things that any decent A&P or TIG welder can fotch up in an afternoon.

As others note, there are good and bad examples in the field. On the
leaky ones I've seen, it's been because things are bent or misaligned
so that the pistons are pre-loaded against the sides of the cylinders,
causing scoring and galling. It's easy to know when its set up right;
when the system is assembled sans O-rings the pistons slide in and out
of the cylinders with no appreciable drag. Also, you must check the
condition of the restraint cable at each annual inspection for fraying
or broken strands.

Thanks, Bob K.

Thanks all for the tip, Wayne, I'll give you a call later this
afternoon.

I just installed the landing gear and retract system in the HP-24, I
did hit the valve with 120 PSI of O2 and it is holding just fine, no
fluid in yet. I am tending to think Bob is right and I'll go ahead and
just go with the shock strut as intended, the gear was holding
pressure after I salvaged it from an HP-18 a few years ago, and that
was after the -18 sat in the trailer for a few decades............I
made the mistake of un-screwing the valve w/o bleeding it
first...............luckily my face wasn't over the valve, and the
ceiling in my shop still has a reminder of what fluid under pressure
does when it is allowed to escape!

Brad

PS..................the HP-24 is all painted
now...................anyone seeing it will be required to not look
too closely at the fuselage, that was a real bugger to sand flat.

I really don't know the HP gear but I thought I'd throw in the idea
that motorcycle "monostrut" rear suspension cartridges are available
in a wide range of sizes and weight carrying capacity. They are a
complete package of spring and air/oil damper. One of them might work
well for a glider wheel.

On Sep 22, 8:29*pm, Bill D wrote:

I really don't know the HP gear but I thought I'd throw in the idea
that motorcycle "monostrut" rear suspension cartridges are available
in a wide range of sizes and weight carrying capacity. *They are a
complete package of spring and air/oil damper. *One of them might work
well for a glider wheel.

Jack Laister used motorcycle coilover dampers in a couple of his
designs, notably including the LP-15 Nugget. I thought about doing
something similar, but it required more vertical space or more swept
volume than I was willing to sacrifice. The HP-18 gear is an off-the-
shelf solution that has worked well for me in the past, and for which
I have the parts and tooling.

Thanks, Bob K.

On Sep 22, 5:33*pm, Eric Greenwell wrote:

Landing in a rough field makes a pilot appreciate a suspension on the
landing gear. Landing faster in rough field makes a pilot REALLY
appreciate a suspension on the landing gear. A well done suspension can
reduce injury some crash situations, but I don't know if the gear in
question was designed to do that.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

My understanding is that Dick having survived a few crashes was a big
believer and building strong crash worthy aircraft.
This was one of the reasons that nearly all of his designs had the
Oleo Strut Landing Gear.
I am sure it saved him from further injury in some of his adventures.
I have done at least one landing where I was very glad to have it.

Brian