Today's Message Index:
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1. 06:43 AM - Re: Re: Fuel flow question (John Franklin)
2. 06:47 AM - Re: Re: Fuel flow question (Hans van der Voort)
3. 09:20 AM - Re: Fuel flow question (taildrags)
4. 12:39 PM - Re: Fuel flow question (John Franklin)
5. 02:06 PM - Re: Fuel flow question (AircamperN11MS)
6. 02:26 PM - Re: Fuel flow question (taildrags)
7. 05:48 PM - Re: Re: Fuel flow question (John Franklin)
8. 06:23 PM - Re: Re: Fuel flow question (glenschweizer@yahoo.com)
9. 07:34 PM - Re: Fuel flow question (GNflyer)
10. 07:40 PM - Re: Spitfire XV (GNflyer)
11. 08:15 PM - Re: Fuel flow question (AircamperN11MS)
Message 1
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| Subject: | Re: Fuel flow question |
Thanks to all who replied; my thinking for placing the tank in the front passenger
compartment was for weight and balance, therefore fuel consumption wouldn't
affect the CG. I guess I could re-run the test with a full tank and figure
out how many "useful" gallons the tank holds. Or, as Oscar suggests, perhaps
install an electric fuel pump system. I do have room behind the firewall for
a header tank, but moving the entire tank there as Shad suggested would be a major
operation since that's where I placed the battery and electrical system.
I'm planning on taking the fuselage and engine to the Corvair College in San Marcos
on March 1st, and there I can get some more opinions.
I'm also planning on attending Brodhead this year and hope to meet a bunch of you
guys there.
Regards,
John Franklin
Prairie Aire 4TA0
Needville, TX
-----Original Message-----
>
>John; since you're building a GN-1, I can't offer direct advice or assistance
(my airplane is a Piet). However, my experience with the 16 gallon tank up ahead
of the passenger in my airplane is that with a gravity feed system, the last
couple of gallons in my tank are unusable except in an emergency, and then
only in level flight. I can cruise on past the 12 gallon mark and dig into that
last few gallons of reserve, but if I raise the nose to full-stall the airplane
or try to power out in a climbing go-around with minimum fuel, I may not
have sufficient fuel flow to sustain engine operation. It does sound like your
test is pretty extreme though I think I've heard of 12 degrees as the nominal
design three-point attitude, which would also be the climb out angle at just
above minimum controllable airspeed.
>
>Although it is certainly simpler and easier to keep your system as-is, gravity
feed only, if you run a Corvair you'll also run a battery and electrical system,
so you can include an electric fuel pump feeding fuel from your main tank
to a small header tank that gravity-feeds the carb. Alternatively, your fuel
pump can continuously feed the carb and the overflow can return to the tank.
>
>Just BS'ing here.
>
>--------
>Oscar Zuniga
>Medford, OR
>Air Camper NX41CC "Scout"
>A75 power
Message 2
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| Subject: | Re: Fuel flow question |
John,=0A=0AI would raise the tank or/and move it forward if at all possible
.=0AYou will see a good angle of climb during take off and you do not want
to starve the engine at that moment.=0A=0AAn non electric option is to add
a small 2-3 gallon tank right behind the firewall, fed from the main tank t
hrough a check valve.=0A2 -3 gallons will get you about 1/2 hour to get to
altitude.=0A=0AFood for thought=0A=0AHans=0A=0ANX15KV=0AWaller, TX=0A=0A=0A
=0A=0AOn Saturday, January 25, 2014 10:21 PM, Ken Bickers <bickers.ken@gmai
l.com> wrote:=0A =0AReading through Firewall Forward by Tony Bingelis (pp.
171-172), Mikee's uncle Tony indicates that for a gravity system, the fuel
system should provide 150% of the take-off fuel consumption. This, he says
, should be verified at maximum climb out angle at the minimum fuel level.
=C2-On page 176, he describes a procedure for conducting this test, which
basically involves chocking the plane at max climb angle. =C2-Starting w
ith an empty tank, add fuel until it just begins to flow steadily from the
disconnected fuel line (keeping the open end at the same height as the carb
inlet). That establishes the unusable fuel amount. At that point, he recom
mends to start the stopwatch and add a gallon of fuel to the tank, measurin
g =C2-how many minutes it takes to drain back out.=C2-=0A=0ACheers, Ken
=0A=0A=0A=0AOn Sat, Jan 25, 2014 at 7:19 PM, taildrags <taildrags@hotmail.c
s@hotmail.com>=0A>=0A>John; since you're building a GN-1, I can't offer dir
ect advice or assistance (my airplane is a Piet). =C2-However, my experie
nce with the 16 gallon tank up ahead of the passenger in my airplane is tha
t with a gravity feed system, the last couple of gallons in my tank are unu
sable except in an emergency, and then only in level flight. =C2-I can cr
uise on past the 12 gallon mark and dig into that last few gallons of reser
ve, but if I raise the nose to full-stall the airplane or try to power out
in a climbing go-around with minimum fuel, I may not have sufficient fuel f
low to sustain engine operation. =C2-It does sound like your test is pret
ty extreme though I think I've heard of 12 degrees as the nominal
design three-point attitude, which would also be the climb out angle at jus
t above minimum controllable airspeed.=0A>=0A>Although it is certainly simp
ler and easier to keep your system as-is, gravity feed only, if you run a C
orvair you'll also run a battery and electrical system, so you can include
an electric fuel pump feeding fuel from your main tank to a small header ta
nk that gravity-feeds the carb. =C2-Alternatively, your fuel pump can con
tinuously feed the carb and the overflow can return to the tank.=0A>=0A>Jus
t BS'ing here.=0A>=0A>--------=0A>Oscar Zuniga=0A>Medford, OR=0A>Air Camper
NX41CC "Scout"=0A>A75 power=0A>=0A>=0A>=0A>=0A>Read this topic online here
:=0A>=0A>http://forums.matronics.com/viewtopic.php?p=417601#417601=0A>=0A
>=0A>=0A>=0A>=0A>=0A>=0A>============0A>st" target=
"_blank">http://www.matronics.com/Navigator?Pietenpol-List=0A>====
========0A>http://forums.matronics.com=0A>======
======0A>le, List Admin.=0A>="_blank">http://www.matronics.com/
=============
Message 3
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| Subject: | Re: Fuel flow question |
John; if you're taking your airplane to the upcoming Corvair College, you will
get excellent advice on how to tackle your fuel flow concerns. Great thinking!
As a passing comment, and others have mentioned the same thing about their experiences,
I have had my airplane in power-on stall configuration till it would
mush indefinitely. In that configuration, it will hold altitude and hang on the
prop, but the point is that the nose is at a ridiculously high attitude. It's
too bad that I didn't have an angle finder on the top longeron so I could
get a reading... it feels like it's 45 degrees nose-high but I'm sure it's not.
This is not a very normal flight configuration, but it's certainly a place
where the only way the airplane is still flying is because power is available.
You want reliable fuel flow with the nose high.
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417614#417614
Message 4
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| Subject: | Re: Fuel flow question |
Hans, Oscar, et al:
It appears I can raise the tank as much as 3", but won't know if that's enough
until I run another flow test. Would it be possible to add an electric pump without
a header tank? Aircraft Spruce sells one rated from 2-3.5psi, which I
wouldn't think would be too much for the Zenith carb I have (Hans has the same
carb). While on the subject, does anyone know how an "interrupter" pump is different
from a regular pump?
-----Original Message-----
From: Hans van der Voort
John,
I would raise the tank or/and move it forward if at all possible.You will see a
good angle of climb during take off and you do not want to starve the engine
at that moment.
An non electric option is to add a small 2-3 gallon tank right behind the firewall,
fed from the main tank through a check valve.2 -3 gallons will get you about
1/2 hour to get to altitude.
Food for thought
Hans
NX15KVWaller, TX
Message 5
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| Subject: | Re: Fuel flow question |
What is preventing you from using a center section wing tank like most others.
It is a proven design, keeps the fuel over the CG and will allow for the front
cockpit to be used as a baggage area when flying to Brodhead. Then you would
also eliminate another failure point, the fuel pump.
Fuel for thought.
--------
Scott Liefeld
Flying N11MS since March 1972
Steel Tube
C-85-12
Wire Wheels
Brodhead in 1996
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417622#417622
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| Subject: | Re: Fuel flow question |
I'm not versed enough on Facet pumps to know the difference between "interrupter"
and regular ones, but I know someone who does. I'll ask.
I also don't know how much fuel pressure the Zenith carb likes or can tolerate,
so I can't say whether your system might operate with a fuel pump but no header
tank. The point of the header tank is to always have a quantity of fuel "up
high" so that the carb always sees reliable gravity head, but then you can use
a fuel pump to lift fuel from the main tank to the header tank and let the
excess return to the main tank... no need for a fuel pressure regulator at the
carb and no fear of overpressuring at the carb. You can almost always make about
99% of the fuel usable with a fuel pump, too.
Scott raises a good point about just using the wing centersection for fuel, but
it's a personal preference thing. Some folks will not tolerate having fuel or
fuel lines anywhere in the cockpit, so they want the tank(s) in the outer wings.
Some folks don't want fuel overhead, so they put it in the nose. It does
simplify matters to have the fuel up in the wing centersection since there is
always plenty of gravity fuel pressure available and the CG doesn't shift with
fuel burn. Getting up there to refuel is a little more work, but not much.
Each approach has its pros and cons, but the plane won't fly without fuel so
it's got to go somewhere.
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417624#417624
Message 7
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| Subject: | Re: Fuel flow question |
Scott,
It would actually be easier for me to put a tank in the center section than it
would be to move the existing tank behind the firewall. The reasons I didn't
put it in the center section are that 1) I would have had to fabricate the tank.
2) It would be a lot harder to access, and 3) I wanted to avoid gas lines
in the cockpit, although having the tank right in front of the cockpit isn't really
much different. I agree with you about the fuel pump being another failure
point, plus the fact it is a unit that contains both fuel and electricity...which
worries me! I wonder if a fuel pump lets fuel pass if it has failed?
Regards,
John F.
-----Original Message-----
>From: AircamperN11MS <Scott.liefeld@lacity.org>
>Sent: Jan 26, 2014 4:05 PM
>To: pietenpol-list@matronics.com
>Subject: Pietenpol-List: Re: Fuel flow question
>
>
>What is preventing you from using a center section wing tank like most others.
It is a proven design, keeps the fuel over the CG and will allow for the front
cockpit to be used as a baggage area when flying to Brodhead. Then you would
also eliminate another failure point, the fuel pump.
>Fuel for thought.
>
>--------
>Scott Liefeld
Message 8
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| Subject: | Re: Fuel flow question |
Hey John
All of your questions and concerns show a lot of intelligence. Most,if not all,
are addressed in Uncle Tony's (Tony Bingelis) books . These are all available
through the EAA store for less than the 100 bucks worth of aggravation you
have experienced.
Fly safe. Glen
Sent from my iPhone
> On Jan 26, 2014, at 5:48 PM, John Franklin <jbfjr@peoplepc.com> wrote:
>
>
> Scott,
>
> It would actually be easier for me to put a tank in the center section than it
would be to move the existing tank behind the firewall. The reasons I didn't
put it in the center section are that 1) I would have had to fabricate the
tank. 2) It would be a lot harder to access, and 3) I wanted to avoid gas lines
in the cockpit, although having the tank right in front of the cockpit isn't
really much different. I agree with you about the fuel pump being another failure
point, plus the fact it is a unit that contains both fuel and electricity...which
worries me! I wonder if a fuel pump lets fuel pass if it has failed?
>
> Regards,
> John F.
>
>
> -----Original Message-----
>> From: AircamperN11MS <Scott.liefeld@lacity.org>
>> Sent: Jan 26, 2014 4:05 PM
>> To: pietenpol-list@matronics.com
>> Subject: Pietenpol-List: Re: Fuel flow question
>>
>>
>> What is preventing you from using a center section wing tank like most others.
It is a proven design, keeps the fuel over the CG and will allow for the front
cockpit to be used as a baggage area when flying to Brodhead. Then you would
also eliminate another failure point, the fuel pump.
>> Fuel for thought.
>>
>> --------
>> Scott Liefeld
>
>
>
>
>
>
>
>
Message 9
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| Subject: | Re: Fuel flow question |
one thing I might suggest if you are still in the wing/center section build stage
might be give some thought to a small tank I the center section. it does complicate
the idea of having a usable fuel gage, but there is no doubt that you
get the most head pressure from it. and it would not have to be real big to give
backup fuel feed if your fuse tank doesn't cut it.I am just not real comfortable
with any combination of electric pumps,check valves-etc. still it would
require a second fuel cut-off valve and the potential to be left on and drain
down possibly flooding the bottom tank over if it was filled. pretty easy to
think of what if's for about any situation. as far as high deck angle once in-flight
I don't think you would ever approach anything like 16 degrees. maybe sitting
on the ground or taking off till you bring the tail up, but after that
even on a go-around I don't think so.- if I truly wanted to limit it to a single
place and keep the tank in the front seat area I'd probably go for doing a
fairly deep forward sloping sump to get the few gallongs forward. and stay as
simple as possible. anyway you got lots of feedback and maybe some of it will
help someone. Raymond
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417652#417652
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an incredible amount of dedication. about 20-25 years ago I was able to make a
trip to the northwest regional in Washington state and drove a rental car on up
into Canada a short ways. we took a ferry out onto Vancouver island and I was
always asking about airports and projects. I ran across a fellow who was best
I remember building a Spitfire from scratch. I have not been able to find out
if he ever got it done or what happened to it. but I'd sure like to know. Raymond
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417654#417654
Message 11
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| Subject: | Re: Fuel flow question |
John,
Since you have asked I will tell you a very true short story.
Here I go. I was asked to do a first flight on a Pietenpol with a Corvair engine.
I agreed to do it. I arrived at the airport with the understanding that everything
I find during a complete inspection will be corrected before I fly it.please
keep in mind that I am an EAA Tech Counsoler for the past 18 years or so.
After six hours of work on the plane it was time to fly it. The plane was built
very well but just needed some fine tuning. It has a center section tank
and a nose tank. The intent of the owner is to use the center section tank as
the primary and the nose as reserve, about 10 gal in the nose. An electric fuel
pump is also on this plane without a bypass and Check valve. Yes electric aircraft
fuel pumps can flow fuel if not turned on. Get the proper one. But the
engine will also have a mechanical pump installed. Back to the flight. I elected
to fly the plane off the nose tank only for CG reasons. I am heavier than the
owner. We tied the plane down and did two or three full power runs for two
minutes at a time with the fuel pump off. It all checked good and this was at
a climb angle. On the runway now, full throttle and ready to rotate when the engine
quit without warming. Now it won't run unless the fuel pump is on. I decided
to fly it with the pump on and all went well. While at pattern alt. I shut
the pump off to see if it would run. I quit again. When the nose tank was full
the engine would run without a pump. After only two gallons were used there
wasn't enough head pressure to push it through the pump and it would quit. It
does however run OK when burning from the center section tank. The owners always
fly it with the pump on. It is a big failure point with no success of any
restart attempt if you run a little low on fuel. I would hate to run out of gas
with 8 gallons on board. So.please put the tank in the proper location so you
don't need to rely on an electric fuel pump. I mean this with all respect to
you and want you to have a very safe and enjoyable airplane.
Respectfully,
--------
Scott Liefeld
Flying N11MS since March 1972
Steel Tube
C-85-12
Wire Wheels
Brodhead in 1996
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417657#417657
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