Pietenpol-List Digest Archive

Sun 01/26/14


Total Messages Posted: 11



Today's Message Index:
----------------------
 
     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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    Time: 06:43:08 AM PST US
    From: John Franklin <jbfjr@peoplepc.com>
    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 &quot;Scout&quot; >A75 power


    Message 2


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    Time: 06:47:39 AM PST US
    From: Hans van der Voort <nx15kv@yahoo.com>
    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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    Time: 09:20:55 AM PST US
    Subject: Re: Fuel flow question
    From: "taildrags" <taildrags@hotmail.com>
    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 &quot;Scout&quot; A75 power Read this topic online here: http://forums.matronics.com/viewtopic.php?p=417614#417614


    Message 4


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    Time: 12:39:12 PM PST US
    From: John Franklin <jbfjr@peoplepc.com>
    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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    Time: 02:06:10 PM PST US
    Subject: Re: Fuel flow question
    From: "AircamperN11MS" <Scott.liefeld@lacity.org>
    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


    Message 6


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    Time: 02:26:36 PM PST US
    Subject: Re: Fuel flow question
    From: "taildrags" <taildrags@hotmail.com>
    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 &quot;Scout&quot; A75 power Read this topic online here: http://forums.matronics.com/viewtopic.php?p=417624#417624


    Message 7


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    Time: 05:48:40 PM PST US
    From: John Franklin <jbfjr@peoplepc.com>
    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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    Time: 06:23:30 PM PST US
    From: glenschweizer@yahoo.com
    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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    Time: 07:34:19 PM PST US
    Subject: Re: Fuel flow question
    From: "GNflyer" <rayeh48@yahoo.com>
    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


    Message 10


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    Time: 07:40:45 PM PST US
    Subject: Re: Spitfire XV
    From: "GNflyer" <rayeh48@yahoo.com>
    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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    Time: 08:15:50 PM PST US
    Subject: Re: Fuel flow question
    From: "AircamperN11MS" <Scott.liefeld@lacity.org>
    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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