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fuel tank venting

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icubob(at)gmail.com
Guest

Posted: Tue Apr 07, 2009 4:38 am Post subject: fuel tank venting

hi all,

  what are builders doing to vent their wing tanks so they drain? one builder i know has a small tube sticking up and bent into the wind for a little''ram'' effect. is this necessary? wouldnt a small hole in the cap suffice?

   bob noffs

  [quote][b]

Lynn Matteson

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

Posted: Tue Apr 07, 2009 5:56 am Post subject: fuel tank venting

It seems like a small hole would cause a vacuum inside the tank, and  

if it didn't lead to siphoning the fuel out through that hole, it  

might cause the engine to starve for fuel until the plane's speed was  

reduced until the siphoning action eventually stopped. My Kitfox, and  

all others that I've seen, have the "small tube sticking up and bent  

into the wind."



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 624.3 hrs

Sensenich 62x46

Electroair direct-fire ignition system

Status: flying





On Apr 7, 2009, at 8:36 AM, bob noffs wrote:



 	  Quote: 	
		   hi all,

  what are builders doing to vent their wing tanks so they drain?  

 one builder i know has a small tube sticking up and bent into the  

 wind for a little''ram'' effect. is this necessary? wouldnt a small  

 hole in the cap suffice?

  bob noffs

 www.matronics.com/contribution _- 

 ============================================================

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Float Flyr

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

Posted: Tue Apr 07, 2009 6:22 am Post subject: fuel tank venting

The cap is generally right in the low pressure are of the wing when in flight so a hole in the cap will in fact cause a partial vacuum on the top of the fuel...  If you forget to put the cap on you will find the tank empty in no time.  The little ram effect tube is to overcome the slight vacuum in that area.  That little tube should be checked before each flight to make sure it is clear and no insects have built nests there.  

   

Noel  

     

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of bob noffs

 Sent: Tuesday, April 07, 2009 10:06 AM

 To: kitfox-list(at)matronics.com

 Subject: fuel tank venting  

  

     

hi all,  

    

 what are builders doing to vent their wing tanks so they drain? one builder i know has a small tube sticking up and bent into the wind for a little''ram'' effect. is this necessary? wouldnt a small hole in the cap suffice?  

    

 bob noffs  

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       [quote][b]

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Fox5flyer
Guest

Posted: Tue Apr 07, 2009 6:34 am Post subject: fuel tank venting

Well stated, Lynn.  Those pitot tubes are there not only for venting, but to 

also provide a light pressurizing to the fuel system.  As I recall, one of 

our valued past members (Don Smythe?) recessed his tank caps and vented the 

tanks similar to early Cessnas.  Seemed to work OK, but he went to a ton of 

work to accomplish it.  The system as designed works very well.

Crappy weather in NE Michigan while waiting for my airstrip to dry out!

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 402+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert





---

matronics(at)bob.brennan.
Guest

Posted: Tue Apr 07, 2009 6:40 am Post subject: fuel tank venting

Those of us that have the main tank under the cowling (me, at least) have a

cap with a small hole which acts only as a vent. I suppose it works well

because the big cooling fan at the front causes an increase in the pressure

in that area. 



My "reserve" wing tank has the bug-nest tube facing into the wind, I am

guessing without that it wouldn't drain at all when I open the petcock. In

fact it drains extremely slowly when not in flight, so the tube helps the

bad plumbing. Bad plumbing = Model II drain tube that goes from the wing

tank to the floor and back up to the outlet of the dash tank, not like you

guys with header tanks behind the seats. Without that "vent tube" I would

probably need a pump.



Bob Brennan - N717GB

ELSA Repairman, inspection rated

1991 UK Model 2 ELSA Kitfox taildragger

Rotax 582 with 3 blade prop

Wrightsville Pa



--

Lynn Matteson

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

Posted: Tue Apr 07, 2009 7:49 am Post subject: fuel tank venting

If I recall correctly, Don (if it was him) had to run a vent line  

clear way out to the tip(s) of the wing(s) so that it/they would be  

higher than the top of the tank(s). And didn't this present a problem  

if/when the wings were folded?



We got 3-4" of snow down here yesterday, Deke.....just enough to want  

to put the skis back on and make tracks in the snow, but the  

accompanying winds made me think better of it. Before I built the new  

set of skis, I wouldn't have thought of having the ordeal of putting  

them back on, but when it's only a 10-minute job, it's definitely a  

do-able job.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 624.3 hrs

Sensenich 62x46

Electroair direct-fire ignition system

Status: flying





On Apr 7, 2009, at 10:30 AM, fox5flyer wrote:



 	  Quote: 	
		   

 <fox5flyer(at)idealwifi.net>



 Well stated, Lynn.  Those pitot tubes are there not only for  

 venting, but to also provide a light pressurizing to the fuel  

 system.  As I recall, one of our valued past members (Don Smythe?)  

 recessed his tank caps and vented the tanks similar to early  

 Cessnas.  Seemed to work OK, but he went to a ton of work to  

 accomplish it.  The system as designed works very well.

 Crappy weather in NE Michigan while waiting for my airstrip to dry  

 out!

 Deke Morisse

 Mikado Michigan

 S5/Subaru/CAP 402+ TT

 "The aim of an argument or discussion should not be victory, but  

 progress."

 - Joseph Joubert

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Apr 07, 2009 11:08 am Post subject: Re: fuel tank venting

On the talk of airstrip , I have water filled roller. I never been happy with it . I am in the process of making a 8 ' wide  30" roller . Will fill with cement -- should be close to 5000 lbs.  I got a few smaller wheel planes come in here and like it nice for them and the amphib float guys - like me . 



Kingfox Tires excel at most terrain. Never used much on asphalt so mine look fine.   Glad to hear the Kevin might get more in. I shipped most of mine to Europe  that I got from him.

 	  Fox5flyer wrote: 	
		  Well stated, Lynn.  Those pitot tubes are there not only for venting, but to 

also provide a light pressurizing to the fuel system.  As I recall, one of 

our valued past members (Don Smythe?) recessed his tank caps and vented the 

tanks similar to early Cessnas.  Seemed to work OK, but he went to a ton of 

work to accomplish it.  The system as designed works very well.

Crappy weather in NE Michigan while waiting for my airstrip to dry out!

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 402+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert





---

_________________
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http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Apr 07, 2009 11:10 am Post subject: Re: fuel tank venting

Bob,   I think you should have pitot tubes on each tank including your dash tank.    I do and have over 1000 hours in this Kitfox trouble free. 

 	  matronics(at)bob.brennan. wrote: 	
		  Those of us that have the main tank under the cowling (me, at least) have a

cap with a small hole which acts only as a vent. I suppose it works well

because the big cooling fan at the front causes an increase in the pressure

in that area. 



My "reserve" wing tank has the bug-nest tube facing into the wind, I am

guessing without that it wouldn't drain at all when I open the petcock. In

fact it drains extremely slowly when not in flight, so the tube helps the

bad plumbing. Bad plumbing = Model II drain tube that goes from the wing

tank to the floor and back up to the outlet of the dash tank, not like you

guys with header tanks behind the seats. Without that "vent tube" I would

probably need a pump.



Bob Brennan - N717GB

ELSA Repairman, inspection rated

1991 UK Model 2 ELSA Kitfox taildragger

Rotax 582 with 3 blade prop

Wrightsville Pa



--

matronics(at)bob.brennan.
Guest

Posted: Tue Apr 07, 2009 11:32 am Post subject: fuel tank venting

You have a pitot on your dash tank cap? Is it the kind of cap that is above

the cowling and you can fill without taking the cowling off? Mine is. I've

seen some fillers under the cowling and I agree a pitot might help that. I

know you have lots of pix - does any show a dash tank with pitot?



Attached is a picture of mine - notice the cap is tilted into the wind. I

also have had no problems with it the was it is, though not nearly as many

hours!



Thanks,

Bob



--

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Apr 07, 2009 3:38 pm Post subject: Re: fuel tank venting

All 3 Pitot tubes for you Bob. btw I never saw an attachment from you. ?

flying 0884.jpg

Description:

Kitfox IV on floats Pitot tubes
www.cfisher.com

Filesize:

34.83 KB

Viewed:

8809 Time(s)

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Tue Apr 07, 2009 5:25 pm Post subject: fuel tank venting

Bob,

That area on top of the cowling ahead of the windshield is a high pressure

area.  The pitot vent is not needed there.



Randy



--

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

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Apr 08, 2009 3:01 am Post subject: Re: fuel tank venting

Randy , I am not sure if it is high pressure or  not there.  I have done tuft testing there and the tufts lift up  in front the cap and the rest  go around it . 

I know once I was transferring fuel from wing tanks to dash tank and I overfilled it , the gas was coming out the pitot tube and spraying on the windshield. Nut sure what that tells you other than I am a dunce.  



I don't think I would want to take a chance on siphoning having a open vent on the cap. 

 	  Quote: 	
		  Bob,

That area on top of the cowling ahead of the windshield is a high pressure

area. The pitot vent is not needed there.



Randy

7suds(at)Chartermi.net
Guest

Posted: Wed Apr 08, 2009 7:21 am Post subject: fuel tank venting

All,

I built a Model 4 XL with a Rotax 503 some years back that had a ten gallon

aluminum dash tank that I built and two six gallon wing tanks. Wing tanks

had standard fuel caps with pitots and shutoffs at the wing root ribs. They

each feed into one of two top ports in the dash tank. Dash tank had a filler

cap that protruded up through the cowl and the cap was not vented (No over

flow spillage if I overfilled while transferring from my wing tanks). Dash

tank had a vent port from the top of the tank to the top port on the right

wing tank. Dash tank had a 12 volt float system with a gauge on the dash. I

would fly until I was at half tank on the dash tank and then transfer from

one wing tank or the other, the amber lines feeding the dash tank ran down

each door post so I was able to see the fuel flow. Some times in flight fuel

did not want to flow so I would put the plane into a forward slip with that

wing high to get it started. I discovered later if I was to transfer some

from each tank so the lines were full and then shut off the valves it would

begin flowing better once in flight.   



Lloyd Cudnohufsky

Model 5 912ul

IVO IFA Rebuild

Northern Mi.



--

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Apr 08, 2009 8:10 am Post subject: Re: fuel tank venting

Lloyd, 

 My poly tank has no vent built into it but I think  you need to have a vent somewhere or you could starve for gas. I have a shut off for each with tank so if they both shut off I have no venting at all on dash tank. 



So it seems necessary to have a vent and in my case the  pitot  serves the purpose. 

Dave

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