I will answer some of your questions below with my experience and opinion.
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Eric
Fogelin
Sent: January 16, 2009 3:32 PM
To: rebel-builders@dcsol.com
Subject: [rebel-builders] Amphib Questions
Stuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the manual.
This way air can enter and leave during large altitude changes. Since waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
WK... I don't get much water in mine from waves, except in the front. This
happens when taxiing in rough water, which splashes into the front gear
well. Then after you take off, it drains to the back, and through the hose
grommets.
2)
I'd like to get more rubber doughnuts for the amphib main gear shocks. What
material are these made from? Is there a US source for the doughnuts?
WK... I replaced mine with the blue Elite front nose gear suspension
doughnuts. These are stiffer and twice the thickness of the original yellow
amphib ones. Have worked great on mine for 500 hours. Good stiff suspension,
but you won't bottom out on these ones.
3)
The main amphib axles are held in place with clamps. Friction and the method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove or
have a captive end.
WK... Have heard of this problem before, can't remember who now, but don't
know how or why this would happen. Mine are solid, and have never moved.
4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have a
100psi effect. I worry that if I have the wheels down and pump to 150psi and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon lines
with the other 10% aluminum in the cabin.)
WK... This is indeed a problem, and I was with another Rebel amphib (Bruce
G.) that had a line blow on him, when we were high up on a mountain lake in
the middle of nowhere. He used to position his valve in the up position, and
I think that would not allow any pressure release. I keep mine in the
neutral middle position, which I think then just causes the pressure to go
to the gear cylinders where it will dissipate. At least they do on mine, as
I think my piston O rings leak a bit. They don't hold pressure for very long
anyway. You don't have to worry about the gear collapsing while on the
ground, due to them being over centre.
5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
WK... Nope, and no impact after 500 hours.
7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WK... They are not great brakes, but do work enough to slow down and turn.
They will never skid, though, if you expect that. I just replaced my pads
recently, as one side was completely worn out. I have also had problems with
the brake lines blowing. Has happened at least 3 times on me so far. Makes
for some tricky handling when trying to come to a stop. You need to shut off
your engine, as soon as it slows down enough that you lose rudder
effectiveness. I think I had some lines that were not up to standard. Am
still planning to replace them before summer.
Eric Fogelin
Elite Amphib N645E
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[rebel-builders] Amphib Questions
-
Wayne G. O'Shea
[rebel-builders] Amphib Questions
CAPS below your text...
----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, January 16, 2009 6:32 PM
Subject: [rebel-builders] Amphib Questions
TOP "T" RAIL
HERE'S THE FIRST US MFG GOOGLE BROUGHT UP THAT MIGHT HELP YOU IF SIMPLY
E-MAILING JEFF CAN'T.
http://www.acmerubber.com/poly.htm
ROTATING >>THAT I'D THINK WOULD ONLY HAPPEN WITH BEARING ISSUES. IF YOUR'S
IS MOVING THE FIRST THING I'D TRY IS POPPING THE SUSPECT AXLE CAP AND SHAVE
IT OFF SLIGHTLY ACROSS THE BOLT FLANGE FACES AND RESINSTALL.
AND FORTH... NEUTRAL TO UP TO NEUTRAL TO UP... TO BLEED OFF ALL PRESSURE.
THAT WAY TEMP EFFECT WILL AT LEAST BE REDUCED BY 100PSI. FWIW>> I REGULARILY
SEE 400 PSI SWINGS WHEN PARKED IN THE HANGAR EVEN DOING THIS. YOU DON'T NEED
ANY PRESSURE ON THE SYSTEM TO KEEP THE GEAR DOWN (provided you have the nose
wheels castered aft)... JUST BE SURE YOU HAVE 100PSI BEFORE PUSHING THE
AIRPLANE BACKWARDS. IN THE WATER, AT THE DOCK OR ON THE LIFT, I ALWAYS
SELECT GEAR DOWN WHEN PARKING THE AIRPLANE. THAT WAY ANY PRESSURE BUILD
LOWERS THE GEAR INSTEAD OF BUILDING PRESSURE.
DONUTS RECOUPE THEIR SHAPE AND KEEPS THE TIRES ROUND. ALSO MAKES IT EASY TO
GREASE THE MAIN GEAR AND ALLOW'S YOU TO TURN THE WHEEL ONCE IN A WHILE SO
BRAKE PAD DOESN'T STICK IN PLACE.
WAY I LIKE IT SINCE I FLY OFF GRASS 95% OF THE TIME.... BUT CAN BE TOUCHY ON
CROSSWIND DAYS ON PAVEMENT....ESPECIALLY TRYING TO TAXI OUT THE ENTRANCE TO
THE ACTIVE. IF MOUNTED TO THE FLOOR YOU SHOULD HAVE SUFFICIENT BRAKES TO
STEER ON A DIME. GO DO A 1700RPM TAXI AND BRAKE DRAG IF YOU CAN'T.
-----------------------------------------------------------------
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----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, January 16, 2009 6:32 PM
Subject: [rebel-builders] Amphib Questions
SMALL 3/32 VENT HOLE IN EACH COMPARTMENT>> DRILLED IN SIDE SKIN TIGHT BELOWStuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come
up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the
manual.
This way air can enter and leave during large altitude changes. Since
waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
TOP "T" RAIL
THERE'S DIFFERENT STYLES OF THESE>>> SUSPECT THEY'RE POLYURETHANE2)
I'd like to get more rubber doughnuts for the amphib main gear shocks.
What
material are these made from? Is there a US source for the doughnuts?
HERE'S THE FIRST US MFG GOOGLE BROUGHT UP THAT MIGHT HELP YOU IF SIMPLY
E-MAILING JEFF CAN'T.
http://www.acmerubber.com/poly.htm
HAVE NEVER SEEN THIS IN ANY OF MINE>> SOME HAVE COMPLAINED OF THE SHAFT3)
The main amphib axles are held in place with clamps. Friction and the
method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove
or
have a captive end.
ROTATING >>THAT I'D THINK WOULD ONLY HAPPEN WITH BEARING ISSUES. IF YOUR'S
IS MOVING THE FIRST THING I'D TRY IS POPPING THE SUSPECT AXLE CAP AND SHAVE
IT OFF SLIGHTLY ACROSS THE BOLT FLANGE FACES AND RESINSTALL.
WHEN THE AIRPLANE IS JUST SITTING YOU SHOULD ALWAYS FLIP THE SELECTOR BACK4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have
a
100psi effect. I worry that if I have the wheels down and pump to 150psi
and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose
my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon
lines
with the other 10% aluminum in the cabin.)
AND FORTH... NEUTRAL TO UP TO NEUTRAL TO UP... TO BLEED OFF ALL PRESSURE.
THAT WAY TEMP EFFECT WILL AT LEAST BE REDUCED BY 100PSI. FWIW>> I REGULARILY
SEE 400 PSI SWINGS WHEN PARKED IN THE HANGAR EVEN DOING THIS. YOU DON'T NEED
ANY PRESSURE ON THE SYSTEM TO KEEP THE GEAR DOWN (provided you have the nose
wheels castered aft)... JUST BE SURE YOU HAVE 100PSI BEFORE PUSHING THE
AIRPLANE BACKWARDS. IN THE WATER, AT THE DOCK OR ON THE LIFT, I ALWAYS
SELECT GEAR DOWN WHEN PARKING THE AIRPLANE. THAT WAY ANY PRESSURE BUILD
LOWERS THE GEAR INSTEAD OF BUILDING PRESSURE.
NO5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
I BLOCK ALL AMPHIBS FOR THE 6 or 7 MONTHS OF WINTER. LETS THE LANDING GEAR6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
DONUTS RECOUPE THEIR SHAPE AND KEEPS THE TIRES ROUND. ALSO MAKES IT EASY TO
GREASE THE MAIN GEAR AND ALLOW'S YOU TO TURN THE WHEEL ONCE IN A WHILE SO
BRAKE PAD DOESN'T STICK IN PLACE.
BRAKING IS MINIMAL IF PEDAL CYLINDERS STILL HOOKED TO THE PEDAL ASSEMBLY.7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WAY I LIKE IT SINCE I FLY OFF GRASS 95% OF THE TIME.... BUT CAN BE TOUCHY ON
CROSSWIND DAYS ON PAVEMENT....ESPECIALLY TRYING TO TAXI OUT THE ENTRANCE TO
THE ACTIVE. IF MOUNTED TO THE FLOOR YOU SHOULD HAVE SUFFICIENT BRAKES TO
STEER ON A DIME. GO DO A 1700RPM TAXI AND BRAKE DRAG IF YOU CAN'T.
Eric Fogelin
Elite Amphib N645E
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-
Jesse Jenks
[rebel-builders] Amphib Questions
I am probably going to buy a valve from a third party supplier so I can mount and possibly plumb it during the construction of my instrument panel. I believe the standard valve supplied by Murphy is made by Barksdale. I am having trouble determining which type of center position to get. Can you guys take a look at this http://www.barksdale.com/barksdalePDFs/ ... 000-DS.pdf and tell me if I want the closed center, floating center, or open center? It sounds like the float center would be best, based on the comments about pressure buildup while sitting.
Thanks.
Jesse
Windows Live
Thanks.
Jesse
_________________________________________________________________From: Walter.Klatt@shaw.ca
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Amphib Questions
Date: Fri, 16 Jan 2009 17:34:04 -0800
I will answer some of your questions below with my experience and opinion.
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Eric
Fogelin
Sent: January 16, 2009 3:32 PM
To: rebel-builders@dcsol.com
Subject: [rebel-builders] Amphib Questions
Stuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the manual.
This way air can enter and leave during large altitude changes. Since waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
WK... I don't get much water in mine from waves, except in the front. This
happens when taxiing in rough water, which splashes into the front gear
well. Then after you take off, it drains to the back, and through the hose
grommets.
2)
I'd like to get more rubber doughnuts for the amphib main gear shocks. What
material are these made from? Is there a US source for the doughnuts?
WK... I replaced mine with the blue Elite front nose gear suspension
doughnuts. These are stiffer and twice the thickness of the original yellow
amphib ones. Have worked great on mine for 500 hours. Good stiff suspension,
but you won't bottom out on these ones.
3)
The main amphib axles are held in place with clamps. Friction and the method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove or
have a captive end.
WK... Have heard of this problem before, can't remember who now, but don't
know how or why this would happen. Mine are solid, and have never moved.
4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have a
100psi effect. I worry that if I have the wheels down and pump to 150psi and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon lines
with the other 10% aluminum in the cabin.)
WK... This is indeed a problem, and I was with another Rebel amphib (Bruce
G.) that had a line blow on him, when we were high up on a mountain lake in
the middle of nowhere. He used to position his valve in the up position, and
I think that would not allow any pressure release. I keep mine in the
neutral middle position, which I think then just causes the pressure to go
to the gear cylinders where it will dissipate. At least they do on mine, as
I think my piston O rings leak a bit. They don't hold pressure for very long
anyway. You don't have to worry about the gear collapsing while on the
ground, due to them being over centre.
5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
WK... Nope, and no impact after 500 hours.
7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WK... They are not great brakes, but do work enough to slow down and turn.
They will never skid, though, if you expect that. I just replaced my pads
recently, as one side was completely worn out. I have also had problems with
the brake lines blowing. Has happened at least 3 times on me so far. Makes
for some tricky handling when trying to come to a stop. You need to shut off
your engine, as soon as it slows down enough that you lose rudder
effectiveness. I think I had some lines that were not up to standard. Am
still planning to replace them before summer.
Eric Fogelin
Elite Amphib N645E
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Windows Live
-
Eric Fogelin
[rebel-builders] Amphib Questions
Looking through my paperwork, Murphy specified a Barksdale 9021-M.
That is how my order receipt reads from FLW (distributor for Barksdale) as I
had to order this part directly myself. I'm not certain how to translate
this into the type of interflow detail you are interested in, but hope that
helps.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Jesse
Jenks
Sent: Friday, January 16, 2009 10:11 PM
To: Builders list
Subject: RE: [rebel-builders] Amphib Questions
I am probably going to buy a valve from a third party supplier so I can
mount and possibly plumb it during the construction of my instrument panel.
I believe the standard valve supplied by Murphy is made by Barksdale. I am
having trouble determining which type of center position to get. Can you
guys take a look at this
http://www.barksdale.com/barksdalePDFs/ ... 000-DS.pdf and tell me
if I want the closed center, floating center, or open center? It sounds like
the float center would be best, based on the comments about pressure buildup
while sitting.
Thanks.
Jesse
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-----------------------------------------------------------------
That is how my order receipt reads from FLW (distributor for Barksdale) as I
had to order this part directly myself. I'm not certain how to translate
this into the type of interflow detail you are interested in, but hope that
helps.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Jesse
Jenks
Sent: Friday, January 16, 2009 10:11 PM
To: Builders list
Subject: RE: [rebel-builders] Amphib Questions
I am probably going to buy a valve from a third party supplier so I can
mount and possibly plumb it during the construction of my instrument panel.
I believe the standard valve supplied by Murphy is made by Barksdale. I am
having trouble determining which type of center position to get. Can you
guys take a look at this
http://www.barksdale.com/barksdalePDFs/ ... 000-DS.pdf and tell me
if I want the closed center, floating center, or open center? It sounds like
the float center would be best, based on the comments about pressure buildup
while sitting.
Thanks.
Jesse
-----------------------------------------------------------------
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-
Eric Fogelin
[rebel-builders] Amphib Questions
I understand all of your comments. I'll seal up the floats and add 3/32"
breather holes, locate polyurethane doughnuts, shave my one axle cap
slightly, reduce pressure when parked, not put floats up on blocks daily
(only for extended non-flying periods), and no pressure bypass valve. Brake
cylinders are floor mounted, so I'll check the pads for glazing, make sure
discs are clean.
Thanks Wayne.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Wayne
G. O'Shea
Sent: Friday, January 16, 2009 8:01 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
CAPS below your text...
----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, January 16, 2009 6:32 PM
Subject: [rebel-builders] Amphib Questions
TOP "T" RAIL
HERE'S THE FIRST US MFG GOOGLE BROUGHT UP THAT MIGHT HELP YOU IF SIMPLY
E-MAILING JEFF CAN'T.
http://www.acmerubber.com/poly.htm
ROTATING >>THAT I'D THINK WOULD ONLY HAPPEN WITH BEARING ISSUES. IF YOUR'S
IS MOVING THE FIRST THING I'D TRY IS POPPING THE SUSPECT AXLE CAP AND SHAVE
IT OFF SLIGHTLY ACROSS THE BOLT FLANGE FACES AND RESINSTALL.
AND FORTH... NEUTRAL TO UP TO NEUTRAL TO UP... TO BLEED OFF ALL PRESSURE.
THAT WAY TEMP EFFECT WILL AT LEAST BE REDUCED BY 100PSI. FWIW>> I REGULARILY
SEE 400 PSI SWINGS WHEN PARKED IN THE HANGAR EVEN DOING THIS. YOU DON'T NEED
ANY PRESSURE ON THE SYSTEM TO KEEP THE GEAR DOWN (provided you have the nose
wheels castered aft)... JUST BE SURE YOU HAVE 100PSI BEFORE PUSHING THE
AIRPLANE BACKWARDS. IN THE WATER, AT THE DOCK OR ON THE LIFT, I ALWAYS
SELECT GEAR DOWN WHEN PARKING THE AIRPLANE. THAT WAY ANY PRESSURE BUILD
LOWERS THE GEAR INSTEAD OF BUILDING PRESSURE.
DONUTS RECOUPE THEIR SHAPE AND KEEPS THE TIRES ROUND. ALSO MAKES IT EASY TO
GREASE THE MAIN GEAR AND ALLOW'S YOU TO TURN THE WHEEL ONCE IN A WHILE SO
BRAKE PAD DOESN'T STICK IN PLACE.
WAY I LIKE IT SINCE I FLY OFF GRASS 95% OF THE TIME.... BUT CAN BE TOUCHY ON
CROSSWIND DAYS ON PAVEMENT....ESPECIALLY TRYING TO TAXI OUT THE ENTRANCE TO
THE ACTIVE. IF MOUNTED TO THE FLOOR YOU SHOULD HAVE SUFFICIENT BRAKES TO
STEER ON A DIME. GO DO A 1700RPM TAXI AND BRAKE DRAG IF YOU CAN'T.
-----------------------------------------------------------------
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breather holes, locate polyurethane doughnuts, shave my one axle cap
slightly, reduce pressure when parked, not put floats up on blocks daily
(only for extended non-flying periods), and no pressure bypass valve. Brake
cylinders are floor mounted, so I'll check the pads for glazing, make sure
discs are clean.
Thanks Wayne.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Wayne
G. O'Shea
Sent: Friday, January 16, 2009 8:01 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
CAPS below your text...
----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, January 16, 2009 6:32 PM
Subject: [rebel-builders] Amphib Questions
SMALL 3/32 VENT HOLE IN EACH COMPARTMENT>> DRILLED IN SIDE SKIN TIGHT BELOWStuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come
up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the
manual.
This way air can enter and leave during large altitude changes. Since
waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
TOP "T" RAIL
THERE'S DIFFERENT STYLES OF THESE>>> SUSPECT THEY'RE POLYURETHANE2)
I'd like to get more rubber doughnuts for the amphib main gear shocks.
What
material are these made from? Is there a US source for the doughnuts?
HERE'S THE FIRST US MFG GOOGLE BROUGHT UP THAT MIGHT HELP YOU IF SIMPLY
E-MAILING JEFF CAN'T.
http://www.acmerubber.com/poly.htm
HAVE NEVER SEEN THIS IN ANY OF MINE>> SOME HAVE COMPLAINED OF THE SHAFT3)
The main amphib axles are held in place with clamps. Friction and the
method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove
or
have a captive end.
ROTATING >>THAT I'D THINK WOULD ONLY HAPPEN WITH BEARING ISSUES. IF YOUR'S
IS MOVING THE FIRST THING I'D TRY IS POPPING THE SUSPECT AXLE CAP AND SHAVE
IT OFF SLIGHTLY ACROSS THE BOLT FLANGE FACES AND RESINSTALL.
WHEN THE AIRPLANE IS JUST SITTING YOU SHOULD ALWAYS FLIP THE SELECTOR BACK4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have
a
100psi effect. I worry that if I have the wheels down and pump to 150psi
and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose
my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon
lines
with the other 10% aluminum in the cabin.)
AND FORTH... NEUTRAL TO UP TO NEUTRAL TO UP... TO BLEED OFF ALL PRESSURE.
THAT WAY TEMP EFFECT WILL AT LEAST BE REDUCED BY 100PSI. FWIW>> I REGULARILY
SEE 400 PSI SWINGS WHEN PARKED IN THE HANGAR EVEN DOING THIS. YOU DON'T NEED
ANY PRESSURE ON THE SYSTEM TO KEEP THE GEAR DOWN (provided you have the nose
wheels castered aft)... JUST BE SURE YOU HAVE 100PSI BEFORE PUSHING THE
AIRPLANE BACKWARDS. IN THE WATER, AT THE DOCK OR ON THE LIFT, I ALWAYS
SELECT GEAR DOWN WHEN PARKING THE AIRPLANE. THAT WAY ANY PRESSURE BUILD
LOWERS THE GEAR INSTEAD OF BUILDING PRESSURE.
NO5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
I BLOCK ALL AMPHIBS FOR THE 6 or 7 MONTHS OF WINTER. LETS THE LANDING GEAR6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
DONUTS RECOUPE THEIR SHAPE AND KEEPS THE TIRES ROUND. ALSO MAKES IT EASY TO
GREASE THE MAIN GEAR AND ALLOW'S YOU TO TURN THE WHEEL ONCE IN A WHILE SO
BRAKE PAD DOESN'T STICK IN PLACE.
BRAKING IS MINIMAL IF PEDAL CYLINDERS STILL HOOKED TO THE PEDAL ASSEMBLY.7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WAY I LIKE IT SINCE I FLY OFF GRASS 95% OF THE TIME.... BUT CAN BE TOUCHY ON
CROSSWIND DAYS ON PAVEMENT....ESPECIALLY TRYING TO TAXI OUT THE ENTRANCE TO
THE ACTIVE. IF MOUNTED TO THE FLOOR YOU SHOULD HAVE SUFFICIENT BRAKES TO
STEER ON A DIME. GO DO A 1700RPM TAXI AND BRAKE DRAG IF YOU CAN'T.
Eric Fogelin
Elite Amphib N645E
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Eric Fogelin
[rebel-builders] Amphib Questions
Thanks for the info Walter.
Per (1), I've started to chase down leaks in the front gear well. Not much
water gets in, but I'll try to locate the obvious places and perhaps put a
bead of RTV around the hydraulic line grommets.
Per(2), my floats came with translucent yellow doughnuts. I'll contact Jeff
to see about more of the same and the blue doughnuts for the Elite trike
nose gear. I'd like to source a US supplier since shipping across the border
is so expensive.
Per (4), I'll not worry about lowering the pressure on the gear when it is
put away in the hangar. I'll just make sure to pump up the system before
pulling it out and make sure that the nose wheels are pointed backwards to
keep them from folding.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Walter
Klatt
Sent: Friday, January 16, 2009 5:34 PM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Amphib Questions
I will answer some of your questions below with my experience and opinion.
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Eric
Fogelin
Sent: January 16, 2009 3:32 PM
To: rebel-builders@dcsol.com
Subject: [rebel-builders] Amphib Questions
Stuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the manual.
This way air can enter and leave during large altitude changes. Since waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
WK... I don't get much water in mine from waves, except in the front. This
happens when taxiing in rough water, which splashes into the front gear
well. Then after you take off, it drains to the back, and through the hose
grommets.
2)
I'd like to get more rubber doughnuts for the amphib main gear shocks. What
material are these made from? Is there a US source for the doughnuts?
WK... I replaced mine with the blue Elite front nose gear suspension
doughnuts. These are stiffer and twice the thickness of the original yellow
amphib ones. Have worked great on mine for 500 hours. Good stiff suspension,
but you won't bottom out on these ones.
3)
The main amphib axles are held in place with clamps. Friction and the method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove or
have a captive end.
WK... Have heard of this problem before, can't remember who now, but don't
know how or why this would happen. Mine are solid, and have never moved.
4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have a
100psi effect. I worry that if I have the wheels down and pump to 150psi and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon lines
with the other 10% aluminum in the cabin.)
WK... This is indeed a problem, and I was with another Rebel amphib (Bruce
G.) that had a line blow on him, when we were high up on a mountain lake in
the middle of nowhere. He used to position his valve in the up position, and
I think that would not allow any pressure release. I keep mine in the
neutral middle position, which I think then just causes the pressure to go
to the gear cylinders where it will dissipate. At least they do on mine, as
I think my piston O rings leak a bit. They don't hold pressure for very long
anyway. You don't have to worry about the gear collapsing while on the
ground, due to them being over centre.
5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
WK... Nope, and no impact after 500 hours.
7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WK... They are not great brakes, but do work enough to slow down and turn.
They will never skid, though, if you expect that. I just replaced my pads
recently, as one side was completely worn out. I have also had problems with
the brake lines blowing. Has happened at least 3 times on me so far. Makes
for some tricky handling when trying to come to a stop. You need to shut off
your engine, as soon as it slows down enough that you lose rudder
effectiveness. I think I had some lines that were not up to standard. Am
still planning to replace them before summer.
Eric Fogelin
Elite Amphib N645E
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Per (1), I've started to chase down leaks in the front gear well. Not much
water gets in, but I'll try to locate the obvious places and perhaps put a
bead of RTV around the hydraulic line grommets.
Per(2), my floats came with translucent yellow doughnuts. I'll contact Jeff
to see about more of the same and the blue doughnuts for the Elite trike
nose gear. I'd like to source a US supplier since shipping across the border
is so expensive.
Per (4), I'll not worry about lowering the pressure on the gear when it is
put away in the hangar. I'll just make sure to pump up the system before
pulling it out and make sure that the nose wheels are pointed backwards to
keep them from folding.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Walter
Klatt
Sent: Friday, January 16, 2009 5:34 PM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Amphib Questions
I will answer some of your questions below with my experience and opinion.
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Eric
Fogelin
Sent: January 16, 2009 3:32 PM
To: rebel-builders@dcsol.com
Subject: [rebel-builders] Amphib Questions
Stuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the manual.
This way air can enter and leave during large altitude changes. Since waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
WK... I don't get much water in mine from waves, except in the front. This
happens when taxiing in rough water, which splashes into the front gear
well. Then after you take off, it drains to the back, and through the hose
grommets.
2)
I'd like to get more rubber doughnuts for the amphib main gear shocks. What
material are these made from? Is there a US source for the doughnuts?
WK... I replaced mine with the blue Elite front nose gear suspension
doughnuts. These are stiffer and twice the thickness of the original yellow
amphib ones. Have worked great on mine for 500 hours. Good stiff suspension,
but you won't bottom out on these ones.
3)
The main amphib axles are held in place with clamps. Friction and the method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove or
have a captive end.
WK... Have heard of this problem before, can't remember who now, but don't
know how or why this would happen. Mine are solid, and have never moved.
4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have a
100psi effect. I worry that if I have the wheels down and pump to 150psi and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon lines
with the other 10% aluminum in the cabin.)
WK... This is indeed a problem, and I was with another Rebel amphib (Bruce
G.) that had a line blow on him, when we were high up on a mountain lake in
the middle of nowhere. He used to position his valve in the up position, and
I think that would not allow any pressure release. I keep mine in the
neutral middle position, which I think then just causes the pressure to go
to the gear cylinders where it will dissipate. At least they do on mine, as
I think my piston O rings leak a bit. They don't hold pressure for very long
anyway. You don't have to worry about the gear collapsing while on the
ground, due to them being over centre.
5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
WK... Nope, and no impact after 500 hours.
7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WK... They are not great brakes, but do work enough to slow down and turn.
They will never skid, though, if you expect that. I just replaced my pads
recently, as one side was completely worn out. I have also had problems with
the brake lines blowing. Has happened at least 3 times on me so far. Makes
for some tricky handling when trying to come to a stop. You need to shut off
your engine, as soon as it slows down enough that you lose rudder
effectiveness. I think I had some lines that were not up to standard. Am
still planning to replace them before summer.
Eric Fogelin
Elite Amphib N645E
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Ken
[rebel-builders] Amphib Questions
Hi Eric
FWIW I am planning a hydraulic pressure relief valve but the only off
the shelf contender that I've found so far (and what I currently plan to
use) is a 150 psi air line regulator. If that doesn't work I'll
manufacture my own, perhaps from a water tank pop off valve. If it
wasn't for the comments on slow internal cylinder leaks, I think this
would be a major issue.
Definitely shave the axle caps to get a good grip if they are loose.
Once upon a time that was a common way to adjust engine bearing
clearances. My caps are tight and if they are not I would expect very
fast pivot wear leading to a broken axle! In fact my caps are so tight
that I can't push them closed without using the bolts. Those little 3/4"
axle end stubs are what resists all sideways gear loads. (A sideways
load tries to twist one arm up more than the other as the load tries to
move the bottom of the tire sideways) Even ignoring that, what else is
there to resist sideways forces from deflecting the two wheel mounting
arms sideways? Certainly not the loose FL 202 pivot bolts. Note how far
your finger can move the pivot arms sideways without the axle installed.
That also means that I'd recommend shaving and RE BORING the holes if
they have worn at all and do not have parallel sides. Shaving the caps
won't help for long if the holes are now worn larger at the outside
edges than in the center of the hole depth. This might be even more
important for anyone using softer die springs instead of elastomeric
pucks. Commercial wheel systems often have a one piece wheel yolk or
side links to take these forces more directly. I can't see any way to
retro-fit in the limited space here. However I have not heard of any
broken axles so the design is probably fine. I'd highly recommend
keeping those axle caps tight though.
Ken
ps. my current task is to machine down the plastic front gear rollers so
they will fit inside the front gear tracks. I'd also like to find larger
washers that will actually span the width of the track cutout at the top
forward curve and be impossible to jam. These little "issues" are sure
increasing build time...
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FWIW I am planning a hydraulic pressure relief valve but the only off
the shelf contender that I've found so far (and what I currently plan to
use) is a 150 psi air line regulator. If that doesn't work I'll
manufacture my own, perhaps from a water tank pop off valve. If it
wasn't for the comments on slow internal cylinder leaks, I think this
would be a major issue.
Definitely shave the axle caps to get a good grip if they are loose.
Once upon a time that was a common way to adjust engine bearing
clearances. My caps are tight and if they are not I would expect very
fast pivot wear leading to a broken axle! In fact my caps are so tight
that I can't push them closed without using the bolts. Those little 3/4"
axle end stubs are what resists all sideways gear loads. (A sideways
load tries to twist one arm up more than the other as the load tries to
move the bottom of the tire sideways) Even ignoring that, what else is
there to resist sideways forces from deflecting the two wheel mounting
arms sideways? Certainly not the loose FL 202 pivot bolts. Note how far
your finger can move the pivot arms sideways without the axle installed.
That also means that I'd recommend shaving and RE BORING the holes if
they have worn at all and do not have parallel sides. Shaving the caps
won't help for long if the holes are now worn larger at the outside
edges than in the center of the hole depth. This might be even more
important for anyone using softer die springs instead of elastomeric
pucks. Commercial wheel systems often have a one piece wheel yolk or
side links to take these forces more directly. I can't see any way to
retro-fit in the limited space here. However I have not heard of any
broken axles so the design is probably fine. I'd highly recommend
keeping those axle caps tight though.
Ken
ps. my current task is to machine down the plastic front gear rollers so
they will fit inside the front gear tracks. I'd also like to find larger
washers that will actually span the width of the track cutout at the top
forward curve and be impossible to jam. These little "issues" are sure
increasing build time...
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Jesse Jenks
[rebel-builders] Amphib Questions
Thanks for digging up that part # Eric. That's the same one I have in my notes that I got from someone at Murphy, so that must be the one they are calling for. That one is a "closed center" according to the Barksdale schematic. That means in the center position all ports are blocked. I'm wondering if it would be more useful to get one of the other options based on the pressure buildup problems being discussed? That way you could use the center position when parked on the ground and pressure in the cylinders would go somewhere else? Where, I'm not exactly sure because I have not seen a schematic of the hydraulic plumbing, but the valve has a return port so it would make sense to route that back to the reservoir. If the system was built that way then the only line that would remain pressurized in the center position would be the one from the pump to the valve. I'm just speculating here, and it would be great to hear from some of you guys who have actual experience with the system as to w
eather this is correct
t
hinking or not.
Thanks
Windows Live
eather this is correct
t
hinking or not.
Thanks
_________________________________________________________________From: elist@whidbey.com
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Amphib Questions
Date: Fri, 16 Jan 2009 22:55:25 -0800
Looking through my paperwork, Murphy specified a Barksdale 9021-M.
That is how my order receipt reads from FLW (distributor for Barksdale) as I
had to order this part directly myself. I'm not certain how to translate
this into the type of interflow detail you are interested in, but hope that
helps.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Jesse
Jenks
Sent: Friday, January 16, 2009 10:11 PM
To: Builders list
Subject: RE: [rebel-builders] Amphib Questions
I am probably going to buy a valve from a third party supplier so I can
mount and possibly plumb it during the construction of my instrument panel.
I believe the standard valve supplied by Murphy is made by Barksdale. I am
having trouble determining which type of center position to get. Can you
guys take a look at this
http://www.barksdale.com/barksdalePDFs/ ... 000-DS.pdf and tell me
if I want the closed center, floating center, or open center? It sounds like
the float center would be best, based on the comments about pressure buildup
while sitting.
Thanks.
Jesse
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Windows Live
-
Wayne G. O'Shea
[rebel-builders] Amphib Questions
Just to point out.. you may think that water is coming from the hose
grommets into the third compartment... but have you sealed your spreader bar
ends.. ie filled the gap between the spreader bar and the float side skin??
The rear spreader was the one I always made sure was sealed.. as it gets
submerged at times. Water enters the spreader.. then the float mounting
stubs and then into the floats thru the bolt access holes in the double
bulkhead.
I was on Lake Nipigon this summer in stuff I really shouldn't have been
playing in (4 foot ++ waves and almost lost my airplane) and by the time I
got to shore the compartment ahead of the front spreader bar, on both
floats, was 3/4 full of water. This from about 30 minutes having waves roll
over the floats while I tried to get across the lake.
----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Saturday, January 17, 2009 2:40 AM
Subject: RE: [rebel-builders] Amphib Questions
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grommets into the third compartment... but have you sealed your spreader bar
ends.. ie filled the gap between the spreader bar and the float side skin??
The rear spreader was the one I always made sure was sealed.. as it gets
submerged at times. Water enters the spreader.. then the float mounting
stubs and then into the floats thru the bolt access holes in the double
bulkhead.
I was on Lake Nipigon this summer in stuff I really shouldn't have been
playing in (4 foot ++ waves and almost lost my airplane) and by the time I
got to shore the compartment ahead of the front spreader bar, on both
floats, was 3/4 full of water. This from about 30 minutes having waves roll
over the floats while I tried to get across the lake.
----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Saturday, January 17, 2009 2:40 AM
Subject: RE: [rebel-builders] Amphib Questions
Thanks for the info Walter.
Per (1), I've started to chase down leaks in the front gear well. Not much
water gets in, but I'll try to locate the obvious places and perhaps put a
bead of RTV around the hydraulic line grommets.
Per(2), my floats came with translucent yellow doughnuts. I'll contact
Jeff
to see about more of the same and the blue doughnuts for the Elite trike
nose gear. I'd like to source a US supplier since shipping across the
border
is so expensive.
Per (4), I'll not worry about lowering the pressure on the gear when it is
put away in the hangar. I'll just make sure to pump up the system before
pulling it out and make sure that the nose wheels are pointed backwards to
keep them from folding.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Walter
Klatt
Sent: Friday, January 16, 2009 5:34 PM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Amphib Questions
I will answer some of your questions below with my experience and opinion.
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Eric
Fogelin
Sent: January 16, 2009 3:32 PM
To: rebel-builders@dcsol.com
Subject: [rebel-builders] Amphib Questions
Stuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come
up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the
manual.
This way air can enter and leave during large altitude changes. Since
waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
WK... I don't get much water in mine from waves, except in the front. This
happens when taxiing in rough water, which splashes into the front gear
well. Then after you take off, it drains to the back, and through the hose
grommets.
2)
I'd like to get more rubber doughnuts for the amphib main gear shocks.
What
material are these made from? Is there a US source for the doughnuts?
WK... I replaced mine with the blue Elite front nose gear suspension
doughnuts. These are stiffer and twice the thickness of the original
yellow
amphib ones. Have worked great on mine for 500 hours. Good stiff
suspension,
but you won't bottom out on these ones.
3)
The main amphib axles are held in place with clamps. Friction and the
method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove
or
have a captive end.
WK... Have heard of this problem before, can't remember who now, but don't
know how or why this would happen. Mine are solid, and have never moved.
4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have
a
100psi effect. I worry that if I have the wheels down and pump to 150psi
and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose
my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon
lines
with the other 10% aluminum in the cabin.)
WK... This is indeed a problem, and I was with another Rebel amphib (Bruce
G.) that had a line blow on him, when we were high up on a mountain lake
in
the middle of nowhere. He used to position his valve in the up position,
and
I think that would not allow any pressure release. I keep mine in the
neutral middle position, which I think then just causes the pressure to go
to the gear cylinders where it will dissipate. At least they do on mine,
as
I think my piston O rings leak a bit. They don't hold pressure for very
long
anyway. You don't have to worry about the gear collapsing while on the
ground, due to them being over centre.
5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
WK... Nope, and no impact after 500 hours.
7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WK... They are not great brakes, but do work enough to slow down and turn.
They will never skid, though, if you expect that. I just replaced my pads
recently, as one side was completely worn out. I have also had problems
with
the brake lines blowing. Has happened at least 3 times on me so far. Makes
for some tricky handling when trying to come to a stop. You need to shut
off
your engine, as soon as it slows down enough that you lose rudder
effectiveness. I think I had some lines that were not up to standard. Am
still planning to replace them before summer.
Eric Fogelin
Elite Amphib N645E
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Walter Klatt
[rebel-builders] Amphib Questions
I don't know for sure where it is coming in on mine, but always assumed it
was through those front grommets. If I land and take off in rough water, I
notice that the compartments ahead of the front struts always get some
water. Otherwise, it is minimal.
The rear ones, including the rear spreaders can be almost submerged at
times, but don't seem to take on much water. I can't say none, because I
always get some, mostly through the tops, I think, as my cap flanges are not
sealed. Same thing happens when it rains. But it is the front ones that get
the most in rough water.
If I have it sitting in the water at the lake, can be for a few days, I get
almost no water in them at all. Except this last year, my right one by the
gear is getting a little. I suspect it may be coming in where the gear
attach bolts goes through the gear well or into the one ahead there. Haven't
really examined it closely yet, and want to check it further too, before the
busy season.
Was hoping to go flying today, but have this thick fog that just won't go
away. Outside the fog, up the valley and on the mountains, it is +15C and
beautiful sunshine, but looks like I could be stuck on the ground again this
weekend.
Walter
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Wayne
G. O'Shea
Sent: January 17, 2009 9:55 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
Just to point out.. you may think that water is coming from the hose
grommets into the third compartment... but have you sealed your spreader bar
ends.. ie filled the gap between the spreader bar and the float side skin??
The rear spreader was the one I always made sure was sealed.. as it gets
submerged at times. Water enters the spreader.. then the float mounting
stubs and then into the floats thru the bolt access holes in the double
bulkhead.
I was on Lake Nipigon this summer in stuff I really shouldn't have been
playing in (4 foot ++ waves and almost lost my airplane) and by the time I
got to shore the compartment ahead of the front spreader bar, on both
floats, was 3/4 full of water. This from about 30 minutes having waves roll
over the floats while I tried to get across the lake.
----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Saturday, January 17, 2009 2:40 AM
Subject: RE: [rebel-builders] Amphib Questions
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was through those front grommets. If I land and take off in rough water, I
notice that the compartments ahead of the front struts always get some
water. Otherwise, it is minimal.
The rear ones, including the rear spreaders can be almost submerged at
times, but don't seem to take on much water. I can't say none, because I
always get some, mostly through the tops, I think, as my cap flanges are not
sealed. Same thing happens when it rains. But it is the front ones that get
the most in rough water.
If I have it sitting in the water at the lake, can be for a few days, I get
almost no water in them at all. Except this last year, my right one by the
gear is getting a little. I suspect it may be coming in where the gear
attach bolts goes through the gear well or into the one ahead there. Haven't
really examined it closely yet, and want to check it further too, before the
busy season.
Was hoping to go flying today, but have this thick fog that just won't go
away. Outside the fog, up the valley and on the mountains, it is +15C and
beautiful sunshine, but looks like I could be stuck on the ground again this
weekend.
Walter
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Wayne
G. O'Shea
Sent: January 17, 2009 9:55 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
Just to point out.. you may think that water is coming from the hose
grommets into the third compartment... but have you sealed your spreader bar
ends.. ie filled the gap between the spreader bar and the float side skin??
The rear spreader was the one I always made sure was sealed.. as it gets
submerged at times. Water enters the spreader.. then the float mounting
stubs and then into the floats thru the bolt access holes in the double
bulkhead.
I was on Lake Nipigon this summer in stuff I really shouldn't have been
playing in (4 foot ++ waves and almost lost my airplane) and by the time I
got to shore the compartment ahead of the front spreader bar, on both
floats, was 3/4 full of water. This from about 30 minutes having waves roll
over the floats while I tried to get across the lake.
----- Original Message -----
From: "Eric Fogelin" <elist@whidbey.com>
To: <rebel-builders@dcsol.com>
Sent: Saturday, January 17, 2009 2:40 AM
Subject: RE: [rebel-builders] Amphib Questions
Thanks for the info Walter.
Per (1), I've started to chase down leaks in the front gear well. Not much
water gets in, but I'll try to locate the obvious places and perhaps put a
bead of RTV around the hydraulic line grommets.
Per(2), my floats came with translucent yellow doughnuts. I'll contact
Jeff
to see about more of the same and the blue doughnuts for the Elite trike
nose gear. I'd like to source a US supplier since shipping across the
border
is so expensive.
Per (4), I'll not worry about lowering the pressure on the gear when it is
put away in the hangar. I'll just make sure to pump up the system before
pulling it out and make sure that the nose wheels are pointed backwards to
keep them from folding.
Eric
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Walter
Klatt
Sent: Friday, January 16, 2009 5:34 PM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Amphib Questions
I will answer some of your questions below with my experience and opinion.
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Eric
Fogelin
Sent: January 16, 2009 3:32 PM
To: rebel-builders@dcsol.com
Subject: [rebel-builders] Amphib Questions
Stuck on the ground and can't continue flight testing due to weeks of bad
weather and dense fog, so thought I'd post a few questions that have come
up
during past amphib testing:
1)
The floats need to be water tight but not air tight according to the
manual.
This way air can enter and leave during large altitude changes. Since
waves
roll over the floats, how are people solving this? I'll be flying from sea
level to 10,000 due to mountains.
WK... I don't get much water in mine from waves, except in the front. This
happens when taxiing in rough water, which splashes into the front gear
well. Then after you take off, it drains to the back, and through the hose
grommets.
2)
I'd like to get more rubber doughnuts for the amphib main gear shocks.
What
material are these made from? Is there a US source for the doughnuts?
WK... I replaced mine with the blue Elite front nose gear suspension
doughnuts. These are stiffer and twice the thickness of the original
yellow
amphib ones. Have worked great on mine for 500 hours. Good stiff
suspension,
but you won't bottom out on these ones.
3)
The main amphib axles are held in place with clamps. Friction and the
method
of attaching the gear arms to the floats is the only thing that keeps the
axles from sliding out. One of my axles likes to slide about 1/8-1/4". It
seems to stay in this position. I worry what will happen when I side load
the wheel during landing. Anyone else have this problem, concern or fix?
Seems like the design should have a pin or the axle machined with groove
or
have a captive end.
WK... Have heard of this problem before, can't remember who now, but don't
know how or why this would happen. Mine are solid, and have never moved.
4)
Hydraulic pressure in the up/down lines for the gear is temperature
sensitive. The change in daytime temperature of 20 or 30 degrees can have
a
100psi effect. I worry that if I have the wheels down and pump to 150psi
and
the sun comes out, that the pressure could easily go over the 250psi limit
and blow lines. Also see (5) below. Or gets real cold at night and I lose
my
pressure and the gear could collapse. I have 3/8" OD lines (90% nylon
lines
with the other 10% aluminum in the cabin.)
WK... This is indeed a problem, and I was with another Rebel amphib (Bruce
G.) that had a line blow on him, when we were high up on a mountain lake
in
the middle of nowhere. He used to position his valve in the up position,
and
I think that would not allow any pressure release. I keep mine in the
neutral middle position, which I think then just causes the pressure to go
to the gear cylinders where it will dissipate. At least they do on mine,
as
I think my piston O rings leak a bit. They don't hold pressure for very
long
anyway. You don't have to worry about the gear collapsing while on the
ground, due to them being over centre.
5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?
6)
Do amphib builders keep their floats on blocks and weight off the wheels
when parked for long periods to keep the rubber shock absorbers from being
permanently deformed and the small amphib wheels from getting flat spots?
WK... Nope, and no impact after 500 hours.
7)
I find the amphib brakes to be ineffective and easy to overheat. They are
small so I'm not surprised, but I wish they were a bit more effective. I
don't think I glazed my pads during break in. Do others share this
experience?
WK... They are not great brakes, but do work enough to slow down and turn.
They will never skid, though, if you expect that. I just replaced my pads
recently, as one side was completely worn out. I have also had problems
with
the brake lines blowing. Has happened at least 3 times on me so far. Makes
for some tricky handling when trying to come to a stop. You need to shut
off
your engine, as soon as it slows down enough that you lose rudder
effectiveness. I think I had some lines that were not up to standard. Am
still planning to replace them before summer.
Eric Fogelin
Elite Amphib N645E
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Ken
[rebel-builders] Amphib Questions
Jesse
Your suspicions are well founded. MAM shipped the 9021-M closed center
valve to me. I would prefer a two position valve
with no center position and a relief valve on the pressure line. OK so I
just won't use the center valve position as that would require two
pressure relief valves to satisfy me. The center position does lock the
fluid in the cylinder if the homemade MAM supplied check valves leak too
much during takeoff and landing. Some guys do have commercial check
valves so there are options. (The check valves are on the inlet and
outlet of the pump and the outlet one ideally prevents flow backward
into the pump).
The "float center" valve would relieve all pressure (back to the
reservoir) in the center
position if that was what you wanted. Some aircraft with mechanical
uplocks would use such a valve. Personally that is not what I want. It
sounds like Wayne might like that one though.
Barksdale has a different definition of "open center" than me. My
industrial/farm open center valves allow free flow from the pressure port to
the return port when in the center position. That is a common method so
that a continuously running pump like a logsplitter can run with no
pressure unless it is actually moving a cylinder. For floats I don't see
any advantage to either style of "open center" valve.
Ken
Jesse Jenks wrote:
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Your suspicions are well founded. MAM shipped the 9021-M closed center
valve to me. I would prefer a two position valve
with no center position and a relief valve on the pressure line. OK so I
just won't use the center valve position as that would require two
pressure relief valves to satisfy me. The center position does lock the
fluid in the cylinder if the homemade MAM supplied check valves leak too
much during takeoff and landing. Some guys do have commercial check
valves so there are options. (The check valves are on the inlet and
outlet of the pump and the outlet one ideally prevents flow backward
into the pump).
The "float center" valve would relieve all pressure (back to the
reservoir) in the center
position if that was what you wanted. Some aircraft with mechanical
uplocks would use such a valve. Personally that is not what I want. It
sounds like Wayne might like that one though.
Barksdale has a different definition of "open center" than me. My
industrial/farm open center valves allow free flow from the pressure port to
the return port when in the center position. That is a common method so
that a continuously running pump like a logsplitter can run with no
pressure unless it is actually moving a cylinder. For floats I don't see
any advantage to either style of "open center" valve.
Ken
Jesse Jenks wrote:
Thanks for digging up that part # Eric. That's the same one I have in
my notes that I got from someone at Murphy, so that must be the one
they are calling for. That one is a "closed center" according to the
Barksdale schematic. That means in the center position all ports are
blocked. I'm wondering if it would be more useful to get one of the
other options based on the pressure buildup problems being discussed?
That way you could use the center position when parked on the ground
and pressure in the cylinders would go somewhere else? Where, I'm not
exactly sure because I have not seen a schematic of the hydraulic
plumbing, but the valve has a return port so it would make sense to
route that back to the reservoir. If the system was built that way
then the only line that would remain pressurized in the center
position would be the one from the pump to the valve. I'm just
speculating here, and it would be great to hear from some of you guys
who have actual experience with the system as to w eather this is
correct t hinking or not. Thanks
_________________________________________________________________From: elist@whidbey.com To: rebel-builders@dcsol.com Subject: RE:
[rebel-builders] Amphib Questions Date: Fri, 16 Jan 2009 22:55:25
-0800
Looking through my paperwork, Murphy specified a Barksdale 9021-M.
That is how my order receipt reads from FLW (distributor for
Barksdale) as I had to order this part directly myself. I'm not
certain how to translate this into the type of interflow detail you
are interested in, but hope that helps.
Eric
-----Original Message----- From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com] On Behalf Of Jesse Jenks Sent:
Friday, January 16, 2009 10:11 PM To: Builders list Subject: RE:
[rebel-builders] Amphib Questions
I am probably going to buy a valve from a third party supplier so I
can mount and possibly plumb it during the construction of my
instrument panel. I believe the standard valve supplied by Murphy
is made by Barksdale. I am having trouble determining which type of
center position to get. Can you guys take a look at this
http://www.barksdale.com/barksdalePDFs/ ... 000-DS.pdf and
tell me if I want the closed center, floating center, or open
center? It sounds like the float center would be best, based on the
comments about pressure buildup while sitting. Thanks. Jesse
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Ken
[rebel-builders] Amphib Questions
Jesse
An accumulator will indeed limit over pressure but you'd have to do more
work pumping it up every time you move the gear and it would be more
expensive and heavier. Accumulators are much more appropriate to
constant pressure systems where they cushion pressure changes. They
would certainly slow down any pressure drops due to small leakages on
our system though.
I suspect that most guys give the pump handle a tug or two before every
landing and takeoff regardless. I think you are wise to stick with what
MAM recommends for the time being.
Ken
Jesse Jenks wrote:
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An accumulator will indeed limit over pressure but you'd have to do more
work pumping it up every time you move the gear and it would be more
expensive and heavier. Accumulators are much more appropriate to
constant pressure systems where they cushion pressure changes. They
would certainly slow down any pressure drops due to small leakages on
our system though.
I suspect that most guys give the pump handle a tug or two before every
landing and takeoff regardless. I think you are wise to stick with what
MAM recommends for the time being.
Ken
Jesse Jenks wrote:
Ken, Thanks for shedding some light on the situation for me. FYI,
Barksdale does offer a two position (no center position) option. Come
to think of it, I wonder what the operational difference would be
between that and a closed center valve in this application. Wayne
says he switches back and forth between center and gear down (I
think) to bleed off pressure while parked. I assume what's happening
there is the pressure is escaping while the valve is in transit
between positions. Like you say, he may be happier with the float
center valve, then he could just leave it in neutral and both
cylinders would vent to the res. That seems like a good option to me
except for the check valve issue that I hadn't heard about yet. It
reminds me of flying the DC-3; you are always looking at the gear
pressure on the ground and adding pressure as it bleeds off. Just a
manual three position valve in that airplane too. Open center I guess
(your definition, not barksdale's) since the engine driven pumps are
alw ays running...hopefully .
If you come up with an acceptable relief valve then you would prefer
a two position valve. What about the possible check valve issue? If
that is a real concern, you could just add an item to the checklist
(like we have on the DC-3) to check gear pressure before taxi,
takeoff, and just before landing. I also wanted to ask if you
considered using an accumulator? That should solve a lot of these
issues (over-pressure, under-pressure). Every airplane I know of has
hydraulic accumulators. I'm sure not an engineer, but I'm definitely
interested in building a better mouse trap. In the end I will
probably use the valve MAM recommends unless someone smarter than me
(you) comes up with a better idea, so please keep us posted of any
developments. Jesse
Date: Sat, 17 Jan 2009 14:20:38 -0500 From: klehman@albedo.net To:
rebel-builders@dcsol.com Subject: Re: [rebel-builders] Amphib
Questions
Jesse
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Bob Patterson
[rebel-builders] Amphib Questions
Hi Walter !
I'm with you -- and Ken !! The standard setup worked fine for me,
as long as I gave it an extra pump or half-pump before takeoff or
landing.
Maybe my valve was strange, but I recall that putting it
into the center position relieved all pressure on the gauge ....
Hardly had to worry anyway - mine leaked off the pressure in
about 4 - 6 hours no matter what position it was in ! ;-)
Worked great, though - 15 strokes up or down ...
(Wayne told me he found a crack in the pump later ... )
--
......bobp
bobp@prosumers.ca
http://www.prosumers.ca/Ramble09
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com
-------------------------------orig.-------------------------
On Sunday 18 January 2009 15:47, Walter Klatt wrote:
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I'm with you -- and Ken !! The standard setup worked fine for me,
as long as I gave it an extra pump or half-pump before takeoff or
landing.
Maybe my valve was strange, but I recall that putting it
into the center position relieved all pressure on the gauge ....
Hardly had to worry anyway - mine leaked off the pressure in
about 4 - 6 hours no matter what position it was in ! ;-)
Worked great, though - 15 strokes up or down ...
(Wayne told me he found a crack in the pump later ... )
--
......bobp
bobp@prosumers.ca
http://www.prosumers.ca/Ramble09
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com
-------------------------------orig.-------------------------
On Sunday 18 January 2009 15:47, Walter Klatt wrote:
Sure you guys aren't over thinking this a bit? The problem is solved
pretty easily by where you leave your selector. EI., just don't leave it
in the up position on a hot day and switching it back and forth does
relieve some pressure. For me, the bigger nuisance is losing pressure on
the up side, and main wheels dropping slowly. I am planning to redo my
O-rings this year, and hopefully can find ones that will do the job
better.
Walter
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Jesse Jenks
Sent: January 17, 2009 6:16 PM
To: Builders list
Subject: RE: [rebel-builders] Amphib Questions
Ken,
Thanks for shedding some light on the situation for me. FYI, Barksdale
does offer a two position (no center position) option. Come to think of
it, I wonder what the operational difference would be between that and a
closed center valve in this application. Wayne says he switches back and
forth between center and gear down (I think) to bleed off pressure while
parked. I assume what's happening there is the pressure is escaping while
the valve is in transit between positions. Like you say, he may be happier
with the float center valve, then he could just leave it in neutral and
both cylinders would vent to the res. That seems like a good option to me
except for the check valve issue that I hadn't heard about yet. It reminds
me of flying the DC-3; you are always looking at the gear pressure on the
ground and adding pressure as it bleeds off. Just a manual three position
valve in that airplane too. Open center I guess (your definition, not
barksdale's) since the engine driven pumps are a
ays running...hopefully
.
If you come up with an acceptable relief valve then you would prefer a two
position valve. What about the possible check valve issue? If that is a
real concern, you could just add an item to the checklist (like we have on
the DC-3) to check gear pressure before taxi, takeoff, and just before
landing. I also wanted to ask if you considered using an accumulator? That
should solve a lot of these issues (over-pressure, under-pressure). Every
airplane I know of has hydraulic accumulators.
I'm sure not an engineer, but I'm definitely interested in building a
better mouse trap. In the end I will probably use the valve MAM recommends
unless someone smarter than me (you) comes up with a better idea, so
please keep us posted of any developments.
Jesse
toDate: Sat, 17 Jan 2009 14:20:38 -0500
From: klehman@albedo.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
Jesse
Your suspicions are well founded. MAM shipped the 9021-M closed center
valve to me. I would prefer a two position valve
with no center position and a relief valve on the pressure line. OK so I
just won't use the center valve position as that would require two
pressure relief valves to satisfy me. The center position does lock the
fluid in the cylinder if the homemade MAM supplied check valves leak too
much during takeoff and landing. Some guys do have commercial check
valves so there are options. (The check valves are on the inlet and
outlet of the pump and the outlet one ideally prevents flow backward
into the pump).
The "float center" valve would relieve all pressure (back to the
reservoir) in the center
position if that was what you wanted. Some aircraft with mechanical
uplocks would use such a valve. Personally that is not what I want. It
sounds like Wayne might like that one though.
Barksdale has a different definition of "open center" than me. My
industrial/farm open center valves allow free flow from the pressure
port
the return port when in the center position. That is a common method so
that a continuously running pump like a logsplitter can run with no
pressure unless it is actually moving a cylinder. For floats I don't see
any advantage to either style of "open center" valve.
Ken
Jesse Jenks wrote:Thanks for digging up that part # Eric. That's the same one I have in
my notes that I got from someone at Murphy, so that must be the one
they are calling for. That one is a "closed center" according to the
Barksdale schematic. That means in the center position all ports are
blocked. I'm wondering if it would be more useful to get one of the
other options based on the pressure buildup problems being discussed?
That way you could use the center position when parked on the ground
and pressure in the cylinders would go somewhere else? Where, I'm not
exactly sure because I have not seen a schematic of the hydraulic
plumbing, but the valve has a return port so it would make sense to
route that back to the reservoir. If the system was built that way
then the only line that would remain pressurized in the center
position would be the one from the pump to the valve. I'm just
speculating here, and it would be great to hear from some of you guys
who have actual experience with the system as to w eather this is
correct t hinking or not. Thanks
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Jesse Jenks
[rebel-builders] Amphib Questions
Bob,
It sounds like you left the valve either up or down while flying or otherwise operating the airplane, and in neutral while parked? This is exactly what I'm trying to figure out: If an open center valve would be better. If that is what you had, it sounds like a deviation from the "standard setup". A one digit change in the part# gives the valve a totally different function in the center position, and to me it's worth some thought at this point if it will make the plane work better. Having no drawings or descriptions of how the system should work, I'm left to figure it out on my own (with your help, hopefully).
You liked how your system worked, and it seems like it is actually different from the standard system. Can you see where I'm coming from? Maybe I want a system like you had even if it's non standard. Maybe it would be useful to analyze this a little bit? Surely there is room for improvement, and surely this is the forum where that should happen?
Thanks
Jesse
Windows Live
It sounds like you left the valve either up or down while flying or otherwise operating the airplane, and in neutral while parked? This is exactly what I'm trying to figure out: If an open center valve would be better. If that is what you had, it sounds like a deviation from the "standard setup". A one digit change in the part# gives the valve a totally different function in the center position, and to me it's worth some thought at this point if it will make the plane work better. Having no drawings or descriptions of how the system should work, I'm left to figure it out on my own (with your help, hopefully).
You liked how your system worked, and it seems like it is actually different from the standard system. Can you see where I'm coming from? Maybe I want a system like you had even if it's non standard. Maybe it would be useful to analyze this a little bit? Surely there is room for improvement, and surely this is the forum where that should happen?
Thanks
Jesse
_________________________________________________________________From: bobp@prosumers.ca
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
Date: Sun, 18 Jan 2009 16:33:31 +0000
Hi Walter !
I'm with you -- and Ken !! The standard setup worked fine for me,
as long as I gave it an extra pump or half-pump before takeoff or
landing.
Maybe my valve was strange, but I recall that putting it
into the center position relieved all pressure on the gauge ....
Hardly had to worry anyway - mine leaked off the pressure in
about 4 - 6 hours no matter what position it was in ! ;-)
Worked great, though - 15 strokes up or down ...
(Wayne told me he found a crack in the pump later ... )
--
......bobp
bobp@prosumers.ca
http://www.prosumers.ca/Ramble09
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com
-------------------------------orig.-------------------------
On Sunday 18 January 2009 15:47, Walter Klatt wrote:Sure you guys aren't over thinking this a bit? The problem is solved
pretty easily by where you leave your selector. EI., just don't leave it
in the up position on a hot day and switching it back and forth does
relieve some pressure. For me, the bigger nuisance is losing pressure on
the up side, and main wheels dropping slowly. I am planning to redo my
O-rings this year, and hopefully can find ones that will do the job
better.
Walter
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Jesse Jenks
Sent: January 17, 2009 6:16 PM
To: Builders list
Subject: RE: [rebel-builders] Amphib Questions
Ken,
Thanks for shedding some light on the situation for me. FYI, Barksdale
does offer a two position (no center position) option. Come to think of
it, I wonder what the operational difference would be between that and a
closed center valve in this application. Wayne says he switches back and
forth between center and gear down (I think) to bleed off pressure while
parked. I assume what's happening there is the pressure is escaping while
the valve is in transit between positions. Like you say, he may be happier
with the float center valve, then he could just leave it in neutral and
both cylinders would vent to the res. That seems like a good option to me
except for the check valve issue that I hadn't heard about yet. It reminds
me of flying the DC-3; you are always looking at the gear pressure on the
ground and adding pressure as it bleeds off. Just a manual three position
valve in that airplane too. Open center I guess (your definition, not
barksdale's) since the engine driven pumps are a
ays running...hopefully
.
If you come up with an acceptable relief valve then you would prefer a two
position valve. What about the possible check valve issue? If that is a
real concern, you could just add an item to the checklist (like we have on
the DC-3) to check gear pressure before taxi, takeoff, and just before
landing. I also wanted to ask if you considered using an accumulator? That
should solve a lot of these issues (over-pressure, under-pressure). Every
airplane I know of has hydraulic accumulators.
I'm sure not an engineer, but I'm definitely interested in building a
better mouse trap. In the end I will probably use the valve MAM recommends
unless someone smarter than me (you) comes up with a better idea, so
please keep us posted of any developments.
Jesse
toDate: Sat, 17 Jan 2009 14:20:38 -0500
From: klehman@albedo.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
Jesse
Your suspicions are well founded. MAM shipped the 9021-M closed center
valve to me. I would prefer a two position valve
with no center position and a relief valve on the pressure line. OK so I
just won't use the center valve position as that would require two
pressure relief valves to satisfy me. The center position does lock the
fluid in the cylinder if the homemade MAM supplied check valves leak too
much during takeoff and landing. Some guys do have commercial check
valves so there are options. (The check valves are on the inlet and
outlet of the pump and the outlet one ideally prevents flow backward
into the pump).
The "float center" valve would relieve all pressure (back to the
reservoir) in the center
position if that was what you wanted. Some aircraft with mechanical
uplocks would use such a valve. Personally that is not what I want. It
sounds like Wayne might like that one though.
Barksdale has a different definition of "open center" than me. My
industrial/farm open center valves allow free flow from the pressure
port
the return port when in the center position. That is a common method so
that a continuously running pump like a logsplitter can run with no
pressure unless it is actually moving a cylinder. For floats I don't see
any advantage to either style of "open center" valve.
Ken
Jesse Jenks wrote:
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Bob Patterson
[rebel-builders] Amphib Questions
Hi Jesse !
As far as I know, mine was completely standard - the installation
was done by Robin, at the factory. I'd just go with the factory
setup - you might like it ! Only change later, IF you find a
problem.....
I see sooooo many guys on here wasting hours trying to
'fix' problems they imagine MIGHT happen -
just "GET IT FLYING"(tm) !!
(it'll never be 'finished' ! ;-) )
Listen to the guys with all the flying experience -
there's lots of little fixes that ARE valuable, and worth doing.
If the valve REALLY was a BIG problem, you'd see LOTS of
emails here from the guys with 1,000+ hours on amphib Rebels
offering a REAL solution.....
(Walter, Carmon .... not me ....)
--
......bobp
bobp@prosumers.ca
http://www.prosumers.ca/Ramble09
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com
-------------------------------orig.-------------------------
On Sunday 18 January 2009 17:46, Jesse Jenks wrote:
Windows Live
As far as I know, mine was completely standard - the installation
was done by Robin, at the factory. I'd just go with the factory
setup - you might like it ! Only change later, IF you find a
problem.....
I see sooooo many guys on here wasting hours trying to
'fix' problems they imagine MIGHT happen -
just "GET IT FLYING"(tm) !!
(it'll never be 'finished' ! ;-) )
Listen to the guys with all the flying experience -
there's lots of little fixes that ARE valuable, and worth doing.
If the valve REALLY was a BIG problem, you'd see LOTS of
emails here from the guys with 1,000+ hours on amphib Rebels
offering a REAL solution.....
(Walter, Carmon .... not me ....)
--
......bobp
bobp@prosumers.ca
http://www.prosumers.ca/Ramble09
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com
-------------------------------orig.-------------------------
On Sunday 18 January 2009 17:46, Jesse Jenks wrote:
_________________________________________________________________Bob,
It sounds like you left the valve either up or down while flying or
otherwise operating the airplane, and in neutral while parked? This is
exactly what I'm trying to figure out: If an open center valve would be
better. If that is what you had, it sounds like a deviation from the
"standard setup". A one digit change in the part# gives the valve a
totally different function in the center position, and to me it's worth
some thought at this point if it will make the plane work better. Having
no drawings or descriptions of how the system should work, I'm left to
figure it out on my own (with your help, hopefully). You liked how your
system worked, and it seems like it is actually different from the
standard system. Can you see where I'm coming from? Maybe I want a system
like you had even if it's non standard. Maybe it would be useful to
analyze this a little bit? Surely there is room for improvement, and
surely this is the forum where that should happen? Thanks
Jesse
From: bobp@prosumers.ca
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions
Date: Sun, 18 Jan 2009 16:33:31 +0000
Hi Walter !
I'm with you -- and Ken !! The standard setup worked fine for me,
as long as I gave it an extra pump or half-pump before takeoff or
landing.
Maybe my valve was strange, but I recall that putting it
into the center position relieved all pressure on the gauge ....
Hardly had to worry anyway - mine leaked off the pressure in
about 4 - 6 hours no matter what position it was in ! ;-)
Worked great, though - 15 strokes up or down ...
(Wayne told me he found a crack in the pump later ... )
--
......bobp
bobp@prosumers.ca
http://www.prosumers.ca/Ramble09
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com
-------------------------------orig.-------------------------
On Sunday 18 January 2009 15:47, Walter Klatt wrote:-----------------------------------------------------------------Sure you guys aren't over thinking this a bit? The problem is solved
pretty easily by where you leave your selector. EI., just don't leave
it in the up position on a hot day and switching it back and forth
does relieve some pressure. For me, the bigger nuisance is losing
pressure on the up side, and main wheels dropping slowly. I am
planning to redo my O-rings this year, and hopefully can find ones
that will do the job better.
Walter
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Jesse Jenks
Sent: January 17, 2009 6:16 PM
To: Builders list
Subject: RE: [rebel-builders] Amphib Questions
Ken,
Thanks for shedding some light on the situation for me. FYI, Barksdale
does offer a two position (no center position) option. Come to think
of it, I wonder what the operational difference would be between that
and a closed center valve in this application. Wayne says he switches
back and forth between center and gear down (I think) to bleed off
pressure while parked. I assume what's happening there is the pressure
is escaping while the valve is in transit between positions. Like you
say, he may be happier with the float center valve, then he could just
leave it in neutral and both cylinders would vent to the res. That
seems like a good option to me except for the check valve issue that I
hadn't heard about yet. It reminds me of flying the DC-3; you are
always looking at the gear pressure on the ground and adding pressure
as it bleeds off. Just a manual three position valve in that airplane
too. Open center I guess (your definition, not barksdale's) since the
engine driven pumps are a
ays running...hopefully
.
If you come up with an acceptable relief valve then you would prefer a
two position valve. What about the possible check valve issue? If that
is a real concern, you could just add an item to the checklist (like
we have on the DC-3) to check gear pressure before taxi, takeoff, and
just before landing. I also wanted to ask if you considered using an
accumulator? That should solve a lot of these issues (over-pressure,
under-pressure). Every airplane I know of has hydraulic accumulators.
I'm sure not an engineer, but I'm definitely interested in building a
better mouse trap. In the end I will probably use the valve MAM
recommends unless someone smarter than me (you) comes up with a better
idea, so please keep us posted of any developments.
Jesse
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