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Fuel Flow, continued.
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dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Jan 24, 2007 12:21 pm Post subject: Fuel Flow, continued.

Lowell,



so if he had his cessna fuel selector at  both  and he lost on tank only

or did he have one tank selected ?

Dave



On topic My Kitfox fuel system seems to work well -- I have no vent tube on 

the wing tanks at all.

---

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Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 24, 2007 12:43 pm Post subject: Fuel Flow, continued.

Dave if you were to loose a cap in flight ... Your ears would get cold....



Seriously though... You would probably lose the fuel in the tank that lost

the cap. And you would have to make another cap.



I lost a cap a couple of years ago.  I used a chrome feed stem for a toilet

and soldered it into a gas cap that I'd removed the plastic from the inside.

T removed the rubber sealing ring before soldering the tube in and once in I

installed the cap with the tube pointing straight up so I could mark forward

on the cap.  Then I bent and trimmed the tube to "look right"



I used a bit of MEK to remove the mark I made for front.  It doesn't leak

and it does work total cost was under $5.00  sure wish I had the gear for

silver soldering.



Big snow storm on here today...  There'll be tons of snow to push around

with the J5 tomorrow!



Still no ice on the bay. So the 'Fox is still on floats.  The rebuild kit

for my fuel pump should be I tomorrow that will take care of an hour or so.



Noel

After thought...   To archive or not...  Not...   Do not archive.



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 24, 2007 12:51 pm Post subject: Fuel Flow, continued.

I've known enough pilots who have lost various quantities of fuel from open

gas fillers in flight  one thing is for sure the gas does get sucked out.

It may, or may not, have something to do with the boundary layers getting

broken up around the gas filler.   I guess the reason isn't so important

especially at the price of gas now days.   



Fluid dynamics can be spooky.



Noel



Do not archive



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Wed Jan 24, 2007 1:13 pm Post subject: Fuel Flow, continued.

At 11:50 AM 1/24/2007, you wrote:

 	  Quote: 	
		  There is one overriding assumption that seems to be common to all the posts

and that is that the  fuel essentially sits quitely and overflows the tank

filler neck because of transfilling.  I don't think that is necessarily the

case.  Based on what I experienced and the tales of others - granted the

sample is very small,  Consider that my flight was in Central Nevada over

the desert and mountains and there is always turbulance there.


	


But the strange thing is that you ended up with one full tank and one empty 

tank. Now my system readily cross feeds from one tank to the other, so if I 

was sloshing fuel out, or siphoning, or whatever, both of my tanks would 

empty at about the same rate. Next time I fill up I'm going to time how 

long it takes one full tank to equilibrate across both tanks, just for 

grins and another data point.

Guy

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

lcfitt(at)sbcglobal.net
Guest

Posted: Wed Jan 24, 2007 2:53 pm Post subject: Fuel Flow, continued.

Guy and others,



I guess my origanal post might be a bit misleading.  When I first noticed 

the low fuel in the right tank, the other tank registered mostly full.  This 

was about an hour into the flight.  I have no memory of what the sight 

gauges looked like on landing after the 12 gallons blew out.



Lowell

---

eskflyer(at)lvcisp.com
Guest

Posted: Wed Jan 24, 2007 3:10 pm Post subject: Fuel Flow, continued.

This is getting ridiculous.

Do you all not know what makes a wing fly?. if not you need to study it .

The area that the filler gas cap is in is in a high suction zone on the wing 

. If you leave it off then yes your fuel will be sucked out fast and 

furiously.

    There should never be a fuel cap left off loose or otherwise. This is 

part of your PREFLIGHT. If you do not have a written preflight checklist 

then I would suggest you make one and follow it everyflight .



Complacency is the excuse of dead pilots



John Perry



DO NOT ARCHIVE

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 24, 2007 4:15 pm Post subject: Fuel Flow, continued.

The more I go over the check lists the more I ask myself the question, "Am I

being complacent today?"  If I'm nor sure I'll check the list again.  I've

only flown once without a checklist.  That was one time was with a very high

time bush pilot in the second seat.  I felt as naked as a Jaybird especially

as I wasn't thoroughly familiar with the operation of that plane.



Going by the list on at least one occasion I have found items that prevented

me from flying.  In my mind it's a lot better to be down here wishing I was

up there than to be up there wishing I was down here!



As john said, and I paraphrase ...  Use your written checklists. 



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Jan 24, 2007 4:35 pm Post subject: Fuel Flow, continued.

Right on, John. Another thing to study might be the lowly insect  

sprayer....air gets blown over a tube which leads to a liquid in a  

tank...sound familiar? Some of these newer folks might never have  

heard of such a contraption, but believe me, they existed at one time.



Lynn

do not archive

On Jan 24, 2007, at 6:09 PM, john perry wrote:



 	  Quote: 	
		   



 This is getting ridiculous.

 Do you all not know what makes a wing fly?. if not you need to  

 study it .

 The area that the filler gas cap is in is in a high suction zone on  

 the wing . If you leave it off then yes your fuel will be sucked  

 out fast and furiously.

    There should never be a fuel cap left off loose or otherwise.  

 This is part of your PREFLIGHT. If you do not have a written  

 preflight checklist then I would suggest you make one and follow it  

 everyflight .



 Complacency is the excuse of dead pilots



 John Perry



 DO NOT ARCHIVE

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Wed Jan 24, 2007 6:18 pm Post subject: Fuel Flow, continued.

Both you guys are right.



But if your tanks can cross feed - via header or otherwise - the tank that

will empty is the one WITH the cap on.  Yes, the fuel is going out of the

tank without the good cap seal, but the air going into the system to

displace the fuel with be going into the other tank - the one with cap on

correctly.  So it is the OTHER tank (the one with a good cap!) that will

empty first.



Torgeir!  Help!



Randy



.           

--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

eskflyer(at)lvcisp.com
Guest

Posted: Wed Jan 24, 2007 6:38 pm Post subject: Fuel Flow, continued.

Randy

I would dare you to test your theory but then that would probably cause a 

engine to quit in flight . No you are wrong on this one ,the tank with the 

lid off will empty first every time .  Remember that you are pulling fuel 

from an opening around 3 inches arcross. and the other tank is feeding a 1/4 

inch line , Now which will empty first .



John Perry



DO NOT ARCHIVE

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Jan 24, 2007 6:51 pm Post subject: Fuel Flow, continued.

John, I have to agree with you as well.



That is why I have a shut off  for each  tank .



Hell , Someone try it and report  the findings.



Did oned Kitfox just go down recently due to a fuel cap missing?



I really think this arguement is getting silly now.

I have no idea if GA aircraft have a vent tube or not but I will say if you 

run on LEFT TANK and it runs dry , your engine stops and Likewise on right. 

But with fuel selector on both- what happens ?



Dave



PS  when i was in flight school nearly 30 years ago we were taught on 

walkaround  to start at right wing tank , engine , prop around nose to left 

wing tank , left leading edge , airlerons, flaps etc  then fuselage stab. , 

elevator , rudder etc and when were  at the tail we were to inspect the fuel 

caps from the  REAR  to ensure they are on and aligned properly.





---

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Wed Jan 24, 2007 7:20 pm Post subject: Fuel Flow, continued.

You are right; I don't want to test it.  But what if the fuel cap is just on

poorly - only one lug caught - or on backwards?    And my cap is less than

2" open cross section.  Yours must be the old pre-unleaded type cap.  



Another factor (which was mentioned by Lowell) was turbulence.  If the plane

is bouncing wildly, the main loss mechanism could be due to splashing and

our discussion of relative pressure would be rather moot.



But someone a couple of months ago reported just what I describe.  Their

tank that emptied first was the one WITH the cap on.



Guy mentioned measuring how fast the two tanks equalize levels.  I have

checked this and the answer is that it depends.  !   As the levels get

closer together, it is not surprising that the flow is slower.  But when

there is significant differential (as in height or pressure differential)

the flow is about half a gallon per minute.   At that rate, it would not

take long to make quite a deficit in your anticipated range. 



Randy



.           

--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 24, 2007 7:30 pm Post subject: Fuel Flow, continued.

The short answer is any time you are siphoning or blowing fuel out of an

aircraft the range is cut down.  When both tanks empty you either come

down.... or look for a real long ladder.      Seriously though without a

reasonable place to do a forced approach any loss of fuel can be dangerous.



Some GA have their vents under the wings facing forward.  Not all aircraft

have any kind of header tank.  I worked on a Super Cub one time that had two

header tanks one in the front and one in the back....  I don't know if that

was something particular to that plane, which was a spotter with the Italian

air force, or not. 



As I understand it the reason for the header tank is to allow the plane to

access fuel while in different attitudes which may stop fuel flow from the

tanks.



Noel

Do not archive

[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Wed Jan 24, 2007 7:38 pm Post subject: Fuel Flow, continued.

At 04:36 PM 1/24/2007, you wrote:

 	  Quote: 	
		  Right on, John. Another thing to study might be the lowly insect

sprayer....air gets blown over a tube which leads to a liquid in a

tank...sound familiar? Some of these newer folks might never have

heard of such a contraption, but believe me, they existed at one time.


	


Do you remember, Lynn, whether that tube was immersed in the liquid? Or was 

there just a hole in the cap? Perhaps you could try it both ways and let us 

know if there's a difference.

Guy Buchanan

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.



Do not archive

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Thu Jan 25, 2007 3:45 am Post subject: Fuel Flow, continued.

Yes, Guy, as I recall, the tube went into the tank, and down to the  

"corner" of the(usually) round tank. Geez, I just thought of another  

similar application of this principle...the paint sprayer gun...DUH!  

on me!  At any rate, the bug sprayer had you putting air pressure  

over that drop tube via a plunger. This air would come out a nozzle  

at the end of the plunger cylinder, and blow directly over the upper  

end of the drop tube. This arrangement was the ideal pressure/siphon  

device, while our planes have a rather crude and inefficient  

"facsimile." Maybe I wouldn't say crude if I was the one who just  

lost a tankful in an hour like Lowell did.

I also had a sandblaster that worked on the bug sprayer principle.

Lynn

do not archive

On Jan 24, 2007, at 10:37 PM, Guy Buchanan wrote:

 	  Quote: 	

 At 04:36 PM 1/24/2007, you wrote:

> Right on, John. Another thing to study might be the lowly insect

> sprayer....air gets blown over a tube which leads to a liquid in a

> tank...sound familiar? Some of these newer folks might never have

> heard of such a contraption, but believe me, they existed at one  

> time.

 Do you remember, Lynn, whether that tube was immersed in the  

 liquid? Or was there just a hole in the cap? Perhaps you could try  

 it both ways and let us know if there's a difference.

 Guy Buchanan

 K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

 Do not archive

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Fox5flyer
Guest

Posted: Thu Jan 25, 2007 4:36 am Post subject: Fuel Flow, continued.

As I recall the NTSB archives are full of incidents related to fuel

starvation and it's probably the number one cause of engine failure, so IMO

this is a good topic and may save some people the pain of a broken airplane,

or worse.

I've been watching this debate with interest because it happened to me with

my old Model II.  I took off with full tanks for a breakfast run and before

I'd gotten ten miles I noticed that my left tank was at the half way mark

while the right tank was full.  I watched it for another minute or so and

saw that the left tank level was still dropping rapidly so I did a 180 and

headed home, landing just about the time the left tank was nearly empty.

What I determined was that two things had happened.  One, the right tank

fuel with the cap not completely secured (on by only one tab) was being

sucked out, and two, the left tank being pressurized by the secure cap/pitot

was pushing the fuel from the left tank down through the header and out the

right tank.

My conclusion was that the loss of fuel was a combination of both the

pressurized left tank and the leaking from the right tank.  I don't know

whether or not the engine would have quit had the left tank run completely

dry, but I suspect it would not have so long as there was still fuel in the

right tank, but that's definitely debatable.

Now, this is different from a tank that has the cap completely missing.

That's a big hole, especially in turbulence where you can lose a lot of fuel

very fast, BUT considering the internal baffling, as the fuel level goes

down the rate of loss will slow, right?  No, because it's still being pushed

out by the pressurized left tank (which is going down) and the right tank

level will stay up until the left tank unports.  Right?  What I'm not sure

about here is what would happen when the left tank empties.

Personally, I'd really like to see the results of a controlled test in

flying conditions to see just what would happen if this was allowed to go

all the way.  It would take the loss of a few gallons of gas and of course

at altitude above an airport with a long runway, but it shouldn't be hard to

make the test.  Probably best with two people so the pilot only flies the

airplane.  Then again, it would depend on the configuration and integrity of

the fuel system because no two are exactly alike.  I have no idea how a test

could be made while on the ground.

Basically I agree with Randy.



Deke Morisse

S5 Outback

NE Michigan and 14F, breezy



---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Jan 25, 2007 5:46 am Post subject: Fuel Flow, continued.

Deke,

Can I ask , What is the reasoning for the vent tube that would allow this to 

happen ?

If you have a pitot cap and a shut off for each wing tank before the header 

tank.



If you need a vent for the header tank make it indenpendant of the wing 

tanks ?



Does this make sense ?



In your case then the right tank would have drained ?



Dave

---

Fox5flyer
Guest

Posted: Thu Jan 25, 2007 6:55 am Post subject: Fuel Flow, continued.

Those are good questions Dave.  The vent tube is simply to allow the header

to fill and stay filled.  The reason why ours vent to the right tank is

because it's the closest one (behind the seat header).  Some folks have the

vent tube independent of the wing tanks, as has been discussed here.

Personally, I don't think the vent tube had anything to do with what

happened to me and had the left cap rather than the right cap been installed

incorrectly the same would have happened in reverse.  In my opinion it's

simply the differential pressure between the tanks when one tank is being

vacuumed (loose cap) and the other pressurized (pitot).  Both tanks are

connected by the header.  Valves on the tank lines would help, but they

create a whole new set of problems.  Overall, the factory setup as designed

by Dan Denny/Dean Wilson/Skystar is sound and like any other airplane is not

foolproof when mistakes are made like forgetting to install a fuel cap or

installing it incorrectly.

Deke

---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Jan 25, 2007 7:14 am Post subject: Fuel Flow, continued.

Deke,



My Buddy has an AVID  with     2 -   12 gal wing tanks.

and a header behind the seat.

Stupidest system i seen. He fills both tank full and if it is  parked  not 

level the  fuel runs out the low tank cap .



I told him to put a shut off on each tank but he has not yet.  Still has to 

worry about fuel transfering tank to tank via the flow thru the header tank. 

Does this make sense ?

Dave

---

kitfoxmike

Joined: 05 Dec 2006
Posts: 373

Posted: Thu Jan 25, 2007 7:22 am Post subject: Re: Fuel Flow, continued.

I made my system simple and it has been mentioned by others, that they use the same. 



 I have NO gascalator, I run from my tanks ,each, to a filter, inline filter, to a shutoff valve, to the header tank, the right tank has the vent that goes to the header tank.  



I have a line that goes from the header to another inline filter and then to a shut off valve then to the fuel pump.  I run one tank at a time, when that tank gets down to about an inch off the bottom of the site hose I switch to the other tank.



I also have the problem with the right tank draining into the left tank, but when the left tank gets full that stops.  Not a problem, but I like to know what I have so I settled on using only one tank at a time.



This time of year I don't go anywhere and I always want  spare fuel, so I put av gas in the right tank, 5 gallons, and only use the left tank.  The right tank with the av fuel will not go bad like auto fuel so that's my reasoning for that.



The hoses I use is the blue hose, which turns green from the auto fuel, from the tanks to the header.  from the header I have aluminum tube, then blue hose at the main filter and shut off valve, then aluminum tube out through the fire wall, then I have auto, fuel injection hose from the fire wall to the fuel pump, from the fuel pump to the carbs, fuel injection hose.



I fly over 250 hrs a year and I have had no problems with this setup.  The hobbs on the airplane just hit 802 yesterday.

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