Amphib Questions
Posted: Sun Feb 19, 2012 5:11 pm
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.
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?
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.
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.)
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?
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?
Eric Fogelin
Elite Amphib N645E
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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.
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?
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.
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.)
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?
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?
Eric Fogelin
Elite Amphib N645E
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