[rebel-builders] Amphib Questions

Ken · Post by **Ken** » Sun Feb 19, 2012 5:11 pm

Probably but my computer is warmer than my shop...

But it does seem wrong to build a system that is pretty much guaranteed
to blow a line sooner or later. It should be easy to make it foolproof
with one relief valve and not leaving the valve in the center position.
Never underestimate a fool, but I still like the foolproof challenge ;)

I presume you have the messages where Angus had to go up a size on the
cross section of a piston o-ring to stop his leak. And the other one
where apparently the leakage was past the piston by way of the threads
where the piston screws onto the shaft.

Ken

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

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Walter Klatt · Post by **Walter Klatt** » Sun Feb 19, 2012 5:11 pm

Yeah, when I am ready to do it, will have to check the archives, and talk to
people here again. Big job to take all that apart, and want to do it right.

Just got back from a flight out to the lake. Finally got a break in the
weather and no fog today, and absolutely beautiful, actually. Big change
from a few weeks ago, where we had snow and cold here. Had a bit of an
inversion, where the OAT was +21 C (70 F) 2500 ft, basically summer weather.
Couldn't complain with +12 and sunny on the ground either.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: January 18, 2009 1:25 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions

Probably but my computer is warmer than my shop...

But it does seem wrong to build a system that is pretty much guaranteed
to blow a line sooner or later. It should be easy to make it foolproof
with one relief valve and not leaving the valve in the center position.
Never underestimate a fool, but I still like the foolproof challenge ;)

I presume you have the messages where Angus had to go up a size on the
cross section of a piston o-ring to stop his leak. And the other one
where apparently the leakage was past the piston by way of the threads
where the piston screws onto the shaft.

Ken

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

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Eric Fogelin · Post by **Eric Fogelin** » Sun Feb 19, 2012 5:12 pm

Hey Walter, the weather also cleared down here near Seattle this afternoon
so was also able to get back in the air for flight testing and runway
landing practice. Best landings since the perfect one I did on my first
flight test.

My wheel axels now seem tight. My axle caps didn't need to be shaved as they
had sufficient gap for tightening, but my axles seem slightly under sized.
So, I filled the few thousands of an inch with aluminum tape as shims. Now
the clamping friction does not let the axle shift under landing loads. So
shimming is another option to consider in addition or instead of shaving the
axle caps.

I understand the comments about just building the Murphy hydraulic system
and don't over think the problems. It is different than most certified
systems, but seems okay. My check valves at the hand pump don't seem to leak
at all (yet) and my system holds pressure for a week or more. With our mild
temperature changes I watch the pressure go up and down but return to the
same pressure at same temp. So, I'm keeping the pressure relief solution in
the back of my mind but leaving the system stock.

This makes hydraulics an operational solution. Low or no pressure when
hangared or extended floating, pump up the pressure for moving/taxiing,
check pressure again right before takeoff and landing (during last GUMP).

Fog in the morning but the promise of more flight testing in the sunny
afternoon tomorrow.

Eric Fogelin
Elite Amphib N645E

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Walter
Klatt
Sent: Sunday, January 18, 2009 4:03 PM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Amphib Questions

Yeah, when I am ready to do it, will have to check the archives, and talk to
people here again. Big job to take all that apart, and want to do it right.

Just got back from a flight out to the lake. Finally got a break in the
weather and no fog today, and absolutely beautiful, actually. Big change
from a few weeks ago, where we had snow and cold here. Had a bit of an
inversion, where the OAT was +21 C (70 F) 2500 ft, basically summer weather.
Couldn't complain with +12 and sunny on the ground either.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: January 18, 2009 1:25 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions

Probably but my computer is warmer than my shop...

But it does seem wrong to build a system that is pretty much guaranteed
to blow a line sooner or later. It should be easy to make it foolproof
with one relief valve and not leaving the valve in the center position.
Never underestimate a fool, but I still like the foolproof challenge ;)

I presume you have the messages where Angus had to go up a size on the
cross section of a piston o-ring to stop his leak. And the other one
where apparently the leakage was past the piston by way of the threads
where the piston screws onto the shaft.

Ken

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

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gleeso · Post by **gleeso** » Sun Feb 19, 2012 5:12 pm

To all you blokes talking about the cold WX over there, just think how
cold it would be without global warming! ;-) Down here the stars at the
Australian Open Tennis are complaining that their shoes melt and stick
to the court, the balls melt in mid flight, and it's only in the mid
30s (c)
How do reckon they will cope the next few days when it's supposed to hit
the 40s?
At least I won't have a problem with the proseal setting. :-)
Regards to all
John Gleeson.
Rebel 804 downunder, ( where its warm, and DRY)

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Angus McKenzie · Post by **Angus McKenzie** » Sun Feb 19, 2012 5:12 pm

My system will only hold peak pressure for a few moments before it bleeds
off.

12 strokes required for full operation in either direction.

I made a check valves for the pump, the stock valves were leaking.

I leave my selector in neutral in flight or parked and give a safety pump in
whatever direction (up or down) necessary to be accident-free went preparing
to taxi wet or dry.

In re-reading the previous post I see Ken already mentioned this following
point:
When I changed "O"rings on one of the nose gear cylinders the CBS Bearing
technician measured everything and said I needed a size larger o-ring than
the stock one. They gave them to me free and that cylinder was immediately
more responsive, as you would expect. So, the next time the floats come off
I'll redo all the o-rings and hopefully improve the overall function of the
hydraulics.

I'm gradually changing out all my lines to metal. What a difference in
braking! And I've metal lines from the pump to the floats now, the entire
brake system has metal tubing from the pedals to the wheels.........Angus

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-----

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Drew Dalgleish · Post by **Drew Dalgleish** » Sun Feb 19, 2012 5:12 pm

At 03:32 PM 16/01/2009 -0800, you wrote:

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.

Small holes in the inspection caps 1/16" or 3/32" will allow pressure
equalization without letting too much water in.

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?

My rubber doughnuts deformed quite early so I replaced them with die
springs which I think work much better than the doughnuts ever did. There
was lots of disscussion about this if you check the archives I'm sure
you'll find lots of reading.

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.

I haven't had this problem Is the axle spinning as well it might be a
bearing problem.

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.)

Like Angus my system has enough internal leaks that it only holds pressure
for a few minutes. I'm sick of chasing them and have learned to live with
it. So I have no wories about overpressure blowing a line. Always make sure
that the nosewheels point towards the back of the floats and they can't
collapse from no pressure. If you ever got negative pressure it's possible
the nosewheels could collapse since they have the least amount of weight on
them. Jacking the front of the floats back up isn't that hard. Having a
leaky system has a safety benefit that I'm always aware of my pressure and
gear position.

5)
Anybody installing a pressure bypass valve incase of getting too
enthusiastic and over-muscling the handpump past the 250psi max?

I've pumped mine up to 300psi to check for leaks if you can do it by
accident I don't want to arm wrestle with you.

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?

Not this one.

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?

My brakes suck too. If you've overheated them they should be glazed. I
think it's very easy to get a bit of oil on the rotors from thrown wheel
bearing grease or from sitting in the water with any oil in the wheelwells
getting washed off. I find that regular generous use of brake cleaner helps
a lot but the brakes are still marginal.

Eric Fogelin
Elite Amphib N645E

Drew

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Ken · Post by **Ken** » Sun Feb 19, 2012 5:12 pm

Well maybe but a caveat might also be wise.

With the stock system and the selector in the center off position,
pressure on both sides of the cylinder can go very high on a hot day
while the gauge is reading as low as zero. Thus the discussion with
Jesse where I question whether it is good to park longterm with the
selector in the center position and the fluid trapped on both sides of
the cylinders. The light weight, low duty cycle cylinders are bound to
seep internally a little but the pressure is still trapped unless the
selector valve also leaks. Except the selector valve is the one part
that nobody has complained about leaking??

Ken

Like Angus my system has enough internal leaks that it only holds pressure
for a few minutes. I'm sick of chasing them and have learned to live with
it. So I have no wories about overpressure blowing a line.

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Drew Dalgleish · Post by **Drew Dalgleish** » Sun Feb 19, 2012 5:12 pm

At 05:48 PM 20/01/2009 -0500, you wrote:

Well maybe but a caveat might also be wise.

With the stock system and the selector in the center off position,
pressure on both sides of the cylinder can go very high on a hot day
while the gauge is reading as low as zero. Thus the discussion with
Jesse where I question whether it is good to park longterm with the
selector in the center position and the fluid trapped on both sides of
the cylinders. The light weight, low duty cycle cylinders are bound to
seep internally a little but the pressure is still trapped unless the
selector valve also leaks. Except the selector valve is the one part
that nobody has complained about leaking??

Ken

Like Angus my system has enough internal leaks that it only holds pressure
for a few minutes. I'm sick of chasing them and have learned to live with
it. So I have no wories about overpressure blowing a line.

Good point Ken I always leave my selector in either the up or down position
so one side of the system is open to the hydraulic resevoir. I finally got
to go flying today after almost 2 months of bad weather and other
commitments absolutely beautiful day keep building guys it's worth it.
Drew

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Jesse Jenks · Post by **Jesse Jenks** » Sun Feb 19, 2012 5:12 pm

Ken,
I just keep thinking an open center valve would be a good and very easy fix to this problem. That would let both sides of the cylinder vent back to the reservoir while the plane is parked. Is the only negative you see that if the check valve leaks the gear could become unsafe during takeoff or landing? It seems like you would not have the selector in the center position during takeoff or landing anyway so it would not matter which type valve you had then, but when you want to leave the plane parked, just put it in neutral (if you had an open center valve) and don't worry about blowing a line.

Date: Tue, 20 Jan 2009 17:48:46 -0500
From: klehman@albedo.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions

Well maybe but a caveat might also be wise.

With the stock system and the selector in the center off position,
pressure on both sides of the cylinder can go very high on a hot day
while the gauge is reading as low as zero. Thus the discussion with
Jesse where I question whether it is good to park longterm with the
selector in the center position and the fluid trapped on both sides of
the cylinders. The light weight, low duty cycle cylinders are bound to
seep internally a little but the pressure is still trapped unless the
selector valve also leaks. Except the selector valve is the one part
that nobody has complained about leaking??

Ken

Like Angus my system has enough internal leaks that it only holds pressure
for a few minutes. I'm sick of chasing them and have learned to live with
it. So I have no wories about overpressure blowing a line.

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Ken · Post by **Ken** » Sun Feb 19, 2012 5:12 pm

Jesse
Your choice.
However for me there is nothing wrong with having the option of using
the center position if the check valve (or relief valve that I plan to
add) leaks. I am staying with the same valve that MAM shipped. It
doesn't take much debris to cause valve leakage and we don't have a
filter in there either ;(
Ken

Jesse Jenks wrote:

Ken, I just keep thinking an open center valve would be a good and
very easy fix to this problem. That would let both sides of the
cylinder vent back to the reservoir while the plane is parked. Is the
only negative you see that if the check valve leaks the gear could
become unsafe during takeoff or landing? It seems like you would not
have the selector in the center position during takeoff or landing
anyway so it would not matter which type valve you had then, but when
you want to leave the plane parked, just put it in neutral (if you
had an open center valve) and don't worry about blowing a line.

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Drew Dalgleish · Post by **Drew Dalgleish** » Sun Feb 19, 2012 5:12 pm

The problem with parking with the selector in the open position is that
sooner or later some well meaning person will move your plane and as soon
as the nosewheels swivel they will retract.

At 10:09 PM 20/01/2009 -0800, you wrote:

Ken,
I just keep thinking an open center valve would be a good and very easy

fix to this problem. That would let both sides of the cylinder vent back to
the reservoir while the plane is parked. Is the only negative you see that
if the check valve leaks the gear could become unsafe during takeoff or
landing? It seems like you would not have the selector in the center
position during takeoff or landing anyway so it would not matter which type
valve you had then, but when you want to leave the plane parked, just put
it in neutral (if you had an open center valve) and don't worry about
blowing a line.
Drew

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Jesse Jenks · Post by **Jesse Jenks** » Sun Feb 19, 2012 5:12 pm

Good points guys.

"The problem with parking with the selector in the open position is that
sooner or later some well meaning person will move your plane and as soon
as the nosewheels swivel they will retract.
Drew"

Date: Wed, 21 Jan 2009 07:49:57 -0500
From: klehman@albedo.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions

Jesse
Your choice.
However for me there is nothing wrong with having the option of using
the center position if the check valve (or relief valve that I plan to
add) leaks. I am staying with the same valve that MAM shipped. It
doesn't take much debris to cause valve leakage and we don't have a
filter in there either ;(
Ken

Jesse Jenks wrote:
Ken, I just keep thinking an open center valve would be a good and
very easy fix to this problem. That would let both sides of the
cylinder vent back to the reservoir while the plane is parked. Is the
only negative you see that if the check valve leaks the gear could
become unsafe during takeoff or landing? It seems like you would not
have the selector in the center position during takeoff or landing
anyway so it would not matter which type valve you had then, but when
you want to leave the plane parked, just put it in neutral (if you
had an open center valve) and don't worry about blowing a line.

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Cecil Shaw · Post by **Cecil Shaw** » Sun Feb 19, 2012 5:12 pm

Hi guys
been reading the threads on anphibs.
ive been flying w mine for 3 years. I have the problem of the pressure
dropping over the 20min range. Never went up in storage, if main gear is set
so it goes over center it will not retract, for the front gear collapsing
when pushing backwards I put a piece of 'u' channel from cdn tire $6 with
red flags over cylinder shaft on both front gear when parked. I give one
pump to remove when ready to go. I used the csa approved air brake lines
from transport trailers and fittings for both gear and brakes. have seen the
pressure in the 300psi range and have had no problems, it is also uv
protected. Carmon Titus uses this on his as well. I went with the stainless
break rotors from ac spruce 3 years ago have had no fade or over heating
probs either, they are about 3/8" thick. not sure if still available had to
make a spacer for the caliper for them to fit.
Cec R014

From: Jesse Jenks <jessejenks@hotmail.com>
Reply-To: <rebel-builders@dcsol.com>
To: Builders list <rebel-builders@dcsol.com>
Subject: RE: [rebel-builders] Amphib Questions
Date: Wed, 21 Jan 2009 10:06:18 -0800

Good points guys.

"The problem with parking with the selector in the open position is that
sooner or later some well meaning person will move your plane and as soon
as the nosewheels swivel they will retract.
Drew"

Date: Wed, 21 Jan 2009 07:49:57 -0500
From: klehman@albedo.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Amphib Questions

Jesse
Your choice.
However for me there is nothing wrong with having the option of using
the center position if the check valve (or relief valve that I plan to
add) leaks. I am staying with the same valve that MAM shipped. It
doesn't take much debris to cause valve leakage and we don't have a
filter in there either ;(
Ken

Jesse Jenks wrote:
Ken, I just keep thinking an open center valve would be a good and
very easy fix to this problem. That would let both sides of the
cylinder vent back to the reservoir while the plane is parked. Is the
only negative you see that if the check valve leaks the gear could
become unsafe during takeoff or landing? It seems like you would not
have the selector in the center position during takeoff or landing
anyway so it would not matter which type valve you had then, but when
you want to leave the plane parked, just put it in neutral (if you
had an open center valve) and don't worry about blowing a line.

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