HP series landing gear info needed

[Brad[_2_]]

Can someone familiar with the HP series of aircraft give me some info
regarding the landing gear shock strut charging process? I am about
ready to install it and need info on fluid type, amount and charging.

Thanks,
Brad
N599GK

[Wayne Paul]

Brad,

Here is the Schreder strut "rebuild" article from my website.
http://www.soaridaho.com/Schreder/Construction/Struts-and-O-rings.html

When I owned the HP-16T currently being flown by Brian Case, the strut was
filled with 5606 hydraulic oil. When I rebuilt my HP-14 I followed Bruce
Patton's advice filled the struts with oil designed for motorcycle for
forks. (The bottle is in my hangar. If you want the exact type, I'll be
happy to go to the airport and forward you the information.) The motorcycle
oil has served me well for the past seven years.

Wayne
http://tinyurl.com/N990-6F


"Brad" wrote in message
...

Can someone familiar with the HP series of aircraft give me some info
regarding the landing gear shock strut charging process? I am about
ready to install it and need info on fluid type, amount and charging.

Thanks,
Brad
N599GK

[T8]

On Sep 22, 1:14*pm, Brad > wrote:
> Can someone familiar with the HP series of aircraft give me some info
> regarding the landing gear shock strut charging process? I am about
> ready to install it and need info on fluid type, amount and charging.
>
> Thanks,
> Brad
> N599GK

Not an HP-18 strut, I hope. I must have rebuilt mine a dozen times.
Usually on great soaring days when it went flat on the way out to the
line. Just weld the ef'fing thing. Or cut off a couple well chosen
lengths of broom handle to fill the space. The basic problem with the
18 strut was no bearing surface and no way to maintain alignment.
When compressed, it would end up rubbing metal on metal inside the
cylinder, it would gall, the galled surface would then make short work
of the o-rings.

You filled each leg with enough auto tranny fluid to reach the piston
at full extension (rusty memory -- maybe 3" in ea leg), assemble,
then charge from N2 bottle (best) or cessnoid type strut pump borrowed
from spam-can mechanic. It takes several hundred psi. On the third
rebuild, go find a broom that needs a shorter handle.

-Evan Ludeman / T8

[Brad[_2_]]

On Sep 22, 11:41*am, T8 > wrote:
> On Sep 22, 1:14*pm, Brad > wrote:
>
> > Can someone familiar with the HP series of aircraft give me some info
> > regarding the landing gear shock strut charging process? I am about
> > ready to install it and need info on fluid type, amount and charging.
>
> > Thanks,
> > Brad
> > N599GK
>
> Not an HP-18 strut, I hope. *I must have rebuilt mine a dozen times.
> Usually on great soaring days when it went flat on the way out to the
> line. *Just weld the ef'fing thing. *Or cut off a couple well chosen
> lengths of broom handle to fill the space. *The basic problem with the
> 18 strut was no bearing surface and no way to maintain alignment.
> When compressed, it would end up rubbing metal on metal inside the
> cylinder, it would gall, the galled surface would then make short work
> of the o-rings.
>
> You filled each leg with enough auto tranny fluid to reach the piston
> at full extension (rusty memory -- maybe 3" in ea leg), assemble,
> then charge from N2 bottle (best) or cessnoid type strut pump borrowed
> from spam-can mechanic. *It takes several hundred psi. *On the third
> rebuild, go find a broom that needs a shorter handle.
>
> -Evan Ludeman / T8

guys, it IS an HP-18 strut...................is this typical of all
HP-18 struts? dealing with a low tire is one thing, dealing with a
defective strut is another, especially on good soaring days!

Brad

[Wayne Paul]

Brad,

I have owned an HP-16T and my current HP-14. They both have struts almost
identical to the HP-18. I haven't had significant problems with either one.
We also have a HP-11 in the area and that bird hasn't exhibited problems.

I initially rebuilt my HP-14 strut as part of getting it ready to fly after
a 20 year hiatus from flight. It may, or may not have needed the rebuild.
I service the strut with N2 prior to each annual condition inspection. It
will last a full year if the stored in the trailer between flights. If I
leave it tied out on the ramp it may need to be serviced midseason.

Wayne


"Brad" wrote in message news:6bfb95c6-1125-466b-b952-75c360f3cfc8@
dl27g2000prd.googlegroups.com...
On Sep 22, 11:41 am, T8 > wrote:
> On Sep 22, 1:14 pm, Brad > wrote:
>
> > Can someone familiar with the HP series of aircraft give me some info
> > regarding the landing gear shock strut charging process? I am about
> > ready to install it and need info on fluid type, amount and charging.
>
> > Thanks,
> > Brad
> > N599GK
>
> Not an HP-18 strut, I hope. I must have rebuilt mine a dozen times.
> Usually on great soaring days when it went flat on the way out to the
> line. Just weld the ef'fing thing. Or cut off a couple well chosen
> lengths of broom handle to fill the space. The basic problem with the
> 18 strut was no bearing surface and no way to maintain alignment.
> When compressed, it would end up rubbing metal on metal inside the
> cylinder, it would gall, the galled surface would then make short work
> of the o-rings.
>
> You filled each leg with enough auto tranny fluid to reach the piston
> at full extension (rusty memory -- maybe 3" in ea leg), assemble,
> then charge from N2 bottle (best) or cessnoid type strut pump borrowed
> from spam-can mechanic. It takes several hundred psi. On the third
> rebuild, go find a broom that needs a shorter handle.
>
> -Evan Ludeman / T8

guys, it IS an HP-18 strut...................is this typical of all
HP-18 struts? dealing with a low tire is one thing, dealing with a
defective strut is another, especially on good soaring days!

Brad

[T8]

On Sep 22, 2:54*pm, Brad > wrote:
> On Sep 22, 11:41*am, T8 > wrote:
>
>
>
>
>
>
>
>
>
> > On Sep 22, 1:14*pm, Brad > wrote:
>
> > > Can someone familiar with the HP series of aircraft give me some info
> > > regarding the landing gear shock strut charging process? I am about
> > > ready to install it and need info on fluid type, amount and charging.
>
> > > Thanks,
> > > Brad
> > > N599GK
>
> > Not an HP-18 strut, I hope. *I must have rebuilt mine a dozen times.
> > Usually on great soaring days when it went flat on the way out to the
> > line. *Just weld the ef'fing thing. *Or cut off a couple well chosen
> > lengths of broom handle to fill the space. *The basic problem with the
> > 18 strut was no bearing surface and no way to maintain alignment.
> > When compressed, it would end up rubbing metal on metal inside the
> > cylinder, it would gall, the galled surface would then make short work
> > of the o-rings.
>
> > You filled each leg with enough auto tranny fluid to reach the piston
> > at full extension (rusty memory -- maybe 3" in ea leg), assemble,
> > then charge from N2 bottle (best) or cessnoid type strut pump borrowed
> > from spam-can mechanic. *It takes several hundred psi. *On the third
> > rebuild, go find a broom that needs a shorter handle.
>
> > -Evan Ludeman / T8
>
> guys, it IS an HP-18 strut...................is this typical of all
> HP-18 struts? dealing with a low tire is one thing, dealing with a
> defective strut is another, especially on good soaring days!
>
> Brad

Take a look at how the thing is built. Ask yourself what prevents
metal/metal contact in the cylinder bore. In my case I think the
piston (the very end, just past the o-ring groove) is what chewed up
the cylinder bores. I remember trying to use a brake cylinder hone to
clean things up. It might have helped a little. My ship may have had
some gear alignment issues that pushed it over the edge. Obviously,
it worked fairly well for others. I've seen other HPs with flat
struts over the years. If I were doing it over again, I really would
weld the sucker (make certain you get the alignment exactly right).
Who needs a shock strut when you land at 30 mph?

[Brad[_2_]]

On Sep 22, 12:30*pm, T8 > wrote:
> On Sep 22, 2:54*pm, Brad > wrote:
>
>
>
>
>
>
>
>
>
> > On Sep 22, 11:41*am, T8 > wrote:
>
> > > On Sep 22, 1:14*pm, Brad > wrote:
>
> > > > Can someone familiar with the HP series of aircraft give me some info
> > > > regarding the landing gear shock strut charging process? I am about
> > > > ready to install it and need info on fluid type, amount and charging.
>
> > > > Thanks,
> > > > Brad
> > > > N599GK
>
> > > Not an HP-18 strut, I hope. *I must have rebuilt mine a dozen times..
> > > Usually on great soaring days when it went flat on the way out to the
> > > line. *Just weld the ef'fing thing. *Or cut off a couple well chosen
> > > lengths of broom handle to fill the space. *The basic problem with the
> > > 18 strut was no bearing surface and no way to maintain alignment.
> > > When compressed, it would end up rubbing metal on metal inside the
> > > cylinder, it would gall, the galled surface would then make short work
> > > of the o-rings.
>
> > > You filled each leg with enough auto tranny fluid to reach the piston
> > > at full extension (rusty memory -- maybe 3" in ea leg), assemble,
> > > then charge from N2 bottle (best) or cessnoid type strut pump borrowed
> > > from spam-can mechanic. *It takes several hundred psi. *On the third
> > > rebuild, go find a broom that needs a shorter handle.
>
> > > -Evan Ludeman / T8
>
> > guys, it IS an HP-18 strut...................is this typical of all
> > HP-18 struts? dealing with a low tire is one thing, dealing with a
> > defective strut is another, especially on good soaring days!
>
> > Brad
>
> Take a look at how the thing is built. * Ask yourself what prevents
> metal/metal contact in the cylinder bore. *In my case I think the
> piston (the very end, just past the o-ring groove) is what chewed up
> the cylinder bores. *I remember trying to use a brake cylinder hone to
> clean things up. *It might have helped a little. *My ship may have had
> some gear alignment issues that pushed it over the edge. *Obviously,
> it worked fairly well for others. *I've seen other HPs with flat
> struts over the years. *If I were doing it over again, I really would
> weld the sucker (make certain you get the alignment exactly right).
> Who needs a shock strut when you land at 30 mph?

I'm leaning more and more for a rigid strut..............instead of
welding, I like the idea of a broom handle/wooden dowel, that's
technology I can appreciate!

Brad

[Wayne Paul]

> wrote:
> On Sep 22, 12:30Â*pm, T8 > wrote:
> > On Sep 22, 2:54Â*pm, Brad > wrote:
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > On Sep 22, 11:41Â*am, T8 > wrote:
> >
> > > > On Sep 22, 1:14Â*pm, Brad > wrote:
> >
> > > > > Can someone familiar with the HP series of aircraft give me some info
> > > > > regarding the landing gear shock strut charging process? I am about
> > > > > ready to install it and need info on fluid type, amount and charging.
> >
> > > > > Thanks,
> > > > > Brad
> > > > > N599GK
> >
> > > > Not an HP-18 strut, I hope. Â*I must have rebuilt mine a dozen times.
> > > > Usually on great soaring days when it went flat on the way out to the
> > > > line. Â*Just weld the ef'fing thing. Â*Or cut off a couple well chosen
> > > > lengths of broom handle to fill the space. Â*The basic problem with the
> > > > 18 strut was no bearing surface and no way to maintain alignment.
> > > > When compressed, it would end up rubbing metal on metal inside the
> > > > cylinder, it would gall, the galled surface would then make short work
> > > > of the o-rings.
> >
> > > > You filled each leg with enough auto tranny fluid to reach the piston
> > > > at full extension (rusty memory -- maybe 3" in ea leg), assemble,
> > > > then charge from N2 bottle (best) or cessnoid type strut pump borrowed
> > > > from spam-can mechanic. Â*It takes several hundred psi. Â*On the third
> > > > rebuild, go find a broom that needs a shorter handle.
> >
> > > > -Evan Ludeman / T8
> >
> > > guys, it IS an HP-18 strut...................is this typical of all
> > > HP-18 struts? dealing with a low tire is one thing, dealing with a
> > > defective strut is another, especially on good soaring days!
> >
> > > Brad
> >
> > Take a look at how the thing is built. Â* Ask yourself what prevents
> > metal/metal contact in the cylinder bore. Â*In my case I think the
> > piston (the very end, just past the o-ring groove) is what chewed up
> > the cylinder bores. Â*I remember trying to use a brake cylinder hone to
> > clean things up. Â*It might have helped a little. Â*My ship may have had
> > some gear alignment issues that pushed it over the edge. Â*Obviously,
> > it worked fairly well for others. Â*I've seen other HPs with flat
> > struts over the years. Â*If I were doing it over again, I really would
> > weld the sucker (make certain you get the alignment exactly right).
> > Who needs a shock strut when you land at 30 mph?
> I'm leaning more and more for a rigid strut..............instead of
> welding, I like the idea of a broom handle/wooden dowel, that's
> technology I can appreciate!
> Brad

Brad,

Give me a call. My cell # is in my Facebook profile.

--
Android Usenet Reader
http://android.newsgroupstats.hk

[Wayne Paul]

> > Brad
> Take a look at how the thing is built. Ask yourself what prevents
> metal/metal contact in the cylinder bore. In my case I think the
> piston (the very end, just past the o-ring groove) is what chewed up
> the cylinder bores. I remember trying to use a brake cylinder hone to
> clean things up. It might have helped a little. My ship may have had
> some gear alignment issues that pushed it over the edge. Obviously,
> it worked fairly well for others. I've seen other HPs with flat
> struts over the years. If I were doing it over again, I really would
> weld the sucker (make certain you get the alignment exactly right).
> Who needs a shock strut when you land at 30 mph?

Brad,

You keep the dirt out with a set of BMX bike fork bellows.

The oil is Honda SS-7 5W.

Wayne
--
Android Usenet Reader
http://android.newsgroupstats.hk

[Brian[_1_]]

> I'm leaning more and more for a rigid strut..............instead of
> welding, I like the idea of a broom handle/wooden dowel, that's
> technology I can appreciate!
>
> Brad

I would avoid this if possible. Or at least try it the oil 1st.
True for 99 landing out of 100 it will be fine. But that one time you
drop in in from about 4 feet or have land in a rough feild. You will
appreciate the suspension.

They obviously can work well. I haven't had my HP16T struts apart for
at least 5 years. I charged them to about 400psi then
which is just enough to begin to compress them when fully loaded. I
did hone them with a brake hone and install X style O-rings then.
They are still holding very close to the original charge I put into
them 5 years ago.

Brian

[Wayne Paul]

> 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

--
Android Usenet Reader
http://android.newsgroupstats.hk

[jim wynhoff]

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
>
> --
> Android Usenet Readerhttp://android.newsgroupstats.hk

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

[Bob Kuykendall]

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.

[Brad[_2_]]

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.

[Eric Greenwell[_4_]]

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)

[T8]

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

[Bill D]

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.

[Bob Kuykendall]

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.

[Brian[_1_]]

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