Hope I'm not thinking of the wrong incident and installation Bobby. I was going on a picture of your pump installation someone else posted. Top notch workmanship but it definitely had a pump inlet filter. Must have been someone else's or an early photo before final configuration.
Tracy
Sent from my iPad
Tracy,
I have no filters on the inlet side of the
pumps. Early on I had one filter at the outlet of each tank but they were
removed after a few flight hours. They were the same GM style filters that may
use on the high pressure side of our fuel systems. Never any indication of fuel
flow problems but no pressure drop data was available from the manufacture. I
was experiencing fuel pressure not tracking manifold pressure on a one to one
basis. It would go higher under boost but sometimes not come down as expected. I
removed the filters at the suggestion of Aeromotive tech support. I still have
the condition and need to try a different regulator. I have one large filter at
the firewall and it always looks clean. I’m confident my power failure was not
fuel “filter” related and I don’t think it was vapor lock. But I’m also not
100% sure it was the Hushpower muffler. I moved throttle several time through its
entire range with no improvements. Sitting on the taxiway after landing the
engine would not make power. A few minutes later when restarted it made full
power. I did call Ed Klepis the day after the FAA inspected the plane and suggested
they check the muffler. No feedback so far.
Just for fun play the attached file in
Google Earth. My poor piloting skill are evident as I let a stiff wind blow me
off center line just after rotation. However tracking the centerline on landing
was not an issue even with the tail wind. As Ed says “emergency’s have a way of
focusing your mind.”
Bobby
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Tracy
Sent: Wednesday, August 31, 2011
12:29 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: CG
Products Intake Manifold
Have to agree with Al W. on this one. I have never seen smoking
gun evidence that vapor lock occurs in the fuel rails. I have seen MANY
smoking guns pointing at problems in the pump inlet circuit.
That pump inlet filter on Bobby Hugh's installation raised a big red
flag for me as a possible cause of his power failure. It looks like the
identical filter that caused the same problem on my 20B. Ed Klepis
talked with me about the problem but unfortunately Bobby is not communicating
about it AFAIK.
BTW, Here is one piece of advice when you experience a power
loss at high throttle. All engine systems are under maximum stress at
full power and it is often the case that if you ask a bit less of them, they
might work better. I understand the urge to firewall the throttle when
power sags at takeoff but TRY reducing throttle momentarily to see if you get
better engine performance. This has saved me from at least three aircraft
accidents. When that clogged inlet filter caused a power sag in the
RV-8, backing off on the throttle lowered the fuel demand of the engine and the
fuel pressure recovered enough to let the engine run normally at reduced
throttle. Same thing applies to other situations. When my Rotax
powered Twinstar started loosing power on climb out I reduced throttle and the
engine recovered. Piston seizure was the problem but reducing throttle
let the piston cool a bit and total seizure was avoided. I replaced
rings & scuffed pistons after nursing it 80 miles to home.
<if there is not a method to bleed down the rail the risk of vapor
lock exists
So you are saying every car built since 1990 has this "vapor
lock" problem? We would see thousands of cars unable to start at every
desert truck stop. This concern for fuel rail is a myth.
Vapor lock is not a myth. It occurs at the fuel pump inlet. Very
important to minimize pressure drop there. You can actually measure how far
your design is from vapor lock. You don't have to guess.
The bleed helps if you totally blew the plumbing from tank to fuel
pump. But much better to fix that plumbing error.
----- Original Message -----
Sent: Tuesday, August
30, 2011 9:14 PM
Subject: [FlyRotary] Re: CG
Products Intake Manifold
HOWEVER..... if there is not a method to bleed down the rail the risk
of vapor lock exists, as the rail heats, the fuel boils, and the vapor gets
trapped in the line.
If you DO put the regulator upstream of the rail, its imperative to be able to
be able to flow fuel past the injectors and to a return line to avoid any
possibility of vapor lock. The easiest way is simply to put the regulator
downstream of the rail and injectors, but again.. this arrangement is more
about preventing vapor lock, not ensuring adequate pressure.
Chris and I were forced into the upstream approach by the Mistral fuel rail
configuration, and I didn't want to mess with drilling out the pinhole and then
running a regulator downstream - Mistral was hard enough to get the intake
from, and we didn't expect getting a replacement part if we had an OOOPS would
have been easy. As others have now found out, Mistral isn't selling parts.
So... anyways.. just wanted to clarify previous post. 1) can regulate
pressure anywhere in the fuel circuit between pumps and injectors. 2) Must
provide for mechanism to flow fuel past injectors to prevent vapor lock.
Dave
On 8/30/2011 11:06 PM, Dave wrote:
No... at the flows and pressures we are using (and barring any major
obstructions between the regulator and the injectors), the regulator can be
anywhere in the circuit and adequately regulate the pressure.
On Chris Barber's install, I purchased the Mistral intake for use on his
engine. The fuel rail was a dead end tube with a pinhole on the end. Presumably
the pinhole was to prevent vapor lock in the fuel rail. The regulator HAD to be
upstream of the injectors when using the intake. We had stable fuel pressures
and no problems getting fuel to the engine.
We had return lines from the pinhole end of the rail, as well as from the
pressure regulator, that fed back to the sump tank. Since there were not check
valves running from the wings to the sump, there was no chance of pressurizing
the sump.
Dave
On 8/30/2011 10:30 PM, CozyGirrrl@aol.com
wrote:
Ed, I must have mispoke
to give this impression, I thought the pressure reg HAD TO be last in line to
maintain pressure in the fuel rail?
Chrissi
& Randi
www.CozyGirrrl.com
CG Products, Custom Aircraft Hardware
Chairwomen, Sun-N-Fun Engine Workshop
If the pressure regulator is place
before the injectors then there is less fresh fuel flowing through the
rails.
<bjh.kmz>
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