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Fuel tank selector

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ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sat Mar 17, 2007 5:22 pm Post subject: Fuel tank selector

Is there a fuel tank selector for the XL or does it feed off of boths tanks at the same time? What exactly does the gascolator do? Is that it's function. Seems to me if you're running on one particular tank and you do say a 360, that's long enough for the fuel line to run dry if the tank it's feeding off of is the high tank in the bank. Is this the case or not?



Thanks

dredmoody(at)cox.net
Guest

Posted: Sat Mar 17, 2007 5:55 pm Post subject: Fuel tank selector

(A) There is a fuel selector valve. It selects  either tank or shuts off both.

  

 (B) The gascolator is a fuel filter/water separator  device

  

 (C) That doesn't happen unless you are very low on  the selected tank and don't coordinate the turn. 

  

 Dred

 [quote]   ---

Tim Juhl

Joined: 21 Mar 2006
Posts: 488
Location: "Thumb" of Michigan

Posted: Sun Mar 18, 2007 1:25 am Post subject: Re: Fuel tank selector

The gascolator is placed at the lowest point of the fuel system, after the fuel selector - in fact, the bottom of the metal bowl protrudes out a hole in the bottom fuselage skin.  It is designed to catch any water and has a fine screen to stop any large chunks of foreign material that may have gotten in your fuel.   You normally drain the gascolator from a petcock located on the underside of the bowl.



Since you are using a corvair engine, you'll probably take William Wynne's advice and follow the gascolator with two fuel pumps installed in series on the firewall.  As I recall the Corvair does not have an engine driven fuel pump so one of the electrical ones must be on at all times.  Many of the Corvair guys install a battery back up in case the primary electrical goes down.   Corvair guys, jump in here and correct me if I'm wrong.



Tim

_________________
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Almost done! It'll fly in spring!

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun Mar 18, 2007 4:56 am Post subject: Re: Fuel tank selector

True, hadn't factored in the coordinated turn thing. I guess that would keep the fuel level in the tanks.



So the gascolator is equivalent to the fuel/water seperator I have on my boat. That's a big filter and water seperator that looks like an oil filter.



Anyway to design it so that there's no tank selector, only an on/off and both tanks feed at all times? Be interesting to take a good look at a Cessna 172s fuel system. There's two tanks on them but only an on/off selector.



Thinking back to the fuel pumps on my boat. My 140 evinrude has a vacuum/mechanical pump, basically it's pumping as long as the engine is turning. I'm wondering if there's so way to adapt one of these as a redundant pump so that it's pumping as long as the engine is turning. Be interesting to try somehow. I like the idea of a mechanical pump.



Anyone buy WW Corvair conversion manual. Does he do anything about redundant spark plugs. I'd have to imagine that would be more difficult, unless there's someone out there making custom Corvair heads with two spark plug holes.



 	  Tim Juhl wrote: 	
		  The gascolator is placed at the lowest point of the fuel system, after the fuel selector - in fact, the bottom of the metal bowl protrudes out a hole in the bottom fuselage skin.  It is designed to catch any water and has a fine screen to stop any large chunks of foreign material that may have gotten in your fuel.   You normally drain the gascolator from a petcock located on the underside of the bowl.



Since you are using a corvair engine, you'll probably take William Wynne's advice and follow the gascolator with two fuel pumps installed in series on the firewall.  As I recall the Corvair does not have an engine driven fuel pump so one of the electrical ones must be on at all times.  Many of the Corvair guys install a battery back up in case the primary electrical goes down.   Corvair guys, jump in here and correct me if I'm wrong.



Tim

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Sun Mar 18, 2007 7:09 am Post subject: Re: Fuel tank selector

The Cessna style will NOT work in the 601XL. There is a very quick little experiment you can do at home to see what will happen if you have a fuel selector set to BOTH in the aircraft.



1. Take a glass of water and two straws.



2. Put one  straw in the glass and hold the other beside the glass.



3. Put both straws in you mouth and suck.



There are ways to create a fuel system that will use both tanks on a lw wing but they are complex and not close to worth the problems.

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

Tim Juhl

Joined: 21 Mar 2006
Posts: 488
Location: "Thumb" of Michigan

Posted: Sun Mar 18, 2007 8:25 am Post subject: Re: Fuel tank selector

The Cessna 172 does not have a "on-off" system.  The 150 did but I can't think of any others.  Also, the Cessnas are notorious for not draining fuel evenly from both tanks when in the "both" position.  Older Cessnas with simple fuel systems like the XL were also susceptible to vapor lock and were placarded to "operate from single tank only above 5000 feet."



If you check the archives I'm sure there has been discussion of engine driven fuel pumps on the Corvair.  WW's website probably has some info too.    I don't remember any being available.



The gascolator is a simpler device than the separator you describe for your boat.  They've been around a long time and are used on all types of engines.  I even have one on my 1953 Ford tractor.



Tim

_________________
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Almost done! It'll fly in spring!

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun Mar 18, 2007 10:07 am Post subject: Re: Fuel tank selector

Thanks. I'm aware of that. At the same time, that's the exact same effect you'd get running on one tank if the sump became dry for some reason, like low on fuel and in an uncoordinated turn, slip to landing, etc. It's almost like you need a small header tank that both tanks feed and that wouldn't be subject to the problems of a near dry tank in a slip.

 	  Gig Giacona wrote: 	
		  The Cessna style will NOT work in the 601XL. There is a very quick little experiment you can do at home to see what will happen if you have a fuel selector set to BOTH in the aircraft.



1. Take a glass of water and two straws.



2. Put one  straw in the glass and hold the other beside the glass.



3. Put both straws in you mouth and suck.



There are ways to create a fuel system that will use both tanks on a lw wing but they are complex and not close to worth the problems.

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Sun Mar 18, 2007 12:03 pm Post subject: Re: Fuel tank selector

The original 601 did have a header tank but it isn't really needed and presents dangers of it's own.



The problem you present while possible really shouldn't be an issue any more than just plain running out of gas while not a good thing is not a fuel system design issue.

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun Mar 18, 2007 1:44 pm Post subject: Re: Fuel tank selector

Just looked at your website. Nice work! Nice workshop too.



 	  Gig Giacona wrote: 	
		  The original 601 did have a header tank but it isn't really needed and presents dangers of it's own.



The problem you present while possible really shouldn't be an issue any more than just plain running out of gas while not a good thing is not a fuel system design issue.

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Sun Mar 18, 2007 2:58 pm Post subject: Fuel tank selector

Feeding from both tanks simultaneously is safe to do in most high  

wing aircraft because the height of the tanks above the tee is  

provides enough head pressure to prevent air from entering the system  

if one tank goes empty before the other. This might not be the case  

for a low wing airplane, there is very little head pressure to keep  

air out of the line.



It is also not a good idea to suck gasoline uphill. It's better to  

have the fuel pump at the low point of the system to ensure good  

gravity feed to the pump inlet then pump the fuel uphill. Drawing  

suction on a gasoline line will make it more likely that the fuel  

will vaporize in the line. Especially on a hot day at full throttle  

with the nose high (takeoff conditions). Fuel pumps don't pump vapor  

worth a damn.



Do an archive search with the term "sucking on fuel" and you'll find  

a whole bunch of info. http://www.matronics.com/search

 	  Quote: 	
		   



 So the gascolator is equivalent to the fuel/water seperator I have  

 on my boat. That's a big filter and water seperator that looks like  

 an oil filter.



 Anyway to design it so that there's no tank selector, only an on/ 

 off and both tanks feed at all times?



 Thinking back to the fuel pumps on my boat. My 140 evinrude has a  

 vacuum/mechanical pump, basically it's pumping as long as the  

 engine is turning. I'm wondering if there's so way to adapt one of  

 these as a redundant pump so that it's pumping as long as the  

 engine is turning. Be interesting to try somehow.


	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Sun Mar 18, 2007 3:25 pm Post subject: Re: Fuel tank selector

Thanks, that's my hanger at KELD



 	  ashontz wrote: 	
		  Just looked at your website. Nice work! Nice workshop too.

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

planecrazydld(at)yahoo.co
Guest

Posted: Sun Mar 18, 2007 6:43 pm Post subject: Fuel tank selector

I have been wondering what the consequences of a small header tank would be other than the fuel inside the cockpit in the even of a crash. Seems like a 2-3 gallon header tank would make those other issues very manageable? 



ashontz <ashontz(at)nbme.org> wrote:  [quote]--> Zenith-List message posted by: "ashontz" 



Thanks. I'm aware of that. At the same time, that's the exact same effect you'd get running on one tank if the sump became dry for some reason, like low on fuel and in an uncoordinated turn, slip to landing, etc. It's almost like you need a small header tank that both tanks feed and that wouldn't be subject to the problems of a near dry tank in a slip.



Gig Giacona wrote:

[quote] The Cessna style will NOT work in the 601XL. There is a very quick little experiment you can do at home to see what will  8:00? 8:25? 8:40? [url= http://tools.search.yahoo.com/shortcuts/?fr=oni_on_mail&#news] Find a flick[/url] in no time

 with the[url= http://tools.search.yahoo.com/shortcuts/?fr=oni_on_mail&#news]Yahoo! Search movie showtime shortcut.[/url]  	  Quote: 	
		  [b]

planecrazydld(at)yahoo.co
Guest

Posted: Sun Mar 18, 2007 6:51 pm Post subject: Fuel tank selector

since I have been considering building the tanks as ProSealed riveted structure, I had been wondering if baffle panels with the swinging one way valves like in all the bigger twins and Citations from Cessna use would be any advantage, They are not really fuel tight but they have a grossly differential leak rate across the baffle plates so the the fuel is coaxed to stay inboard at all times as it is depleted



Gig Giacona <wr.giacona(at)suddenlink.net> wrote:  [quote]--> Zenith-List message posted by: "Gig Giacona" 



The original 601 did have a header tank but it isn't really needed and presents dangers of it's own.



The problem you present while possible really shouldn't be an issue any more than just plain running out of gas while not a good thing is not a fuel system design issue.



--------

W.R. "Gig"  Harleysville (SE) PA

  Zodiac 601XL/Corvair?

     Looking for earth-friendly autos? 

 Browse Top Cars by "Green Rating" at Yahoo! Autos' Green Center.   [quote][b]

jhstarn(at)verizon.net
Guest

Posted: Sun Mar 18, 2007 7:12 pm Post subject: Fuel tank selector

It called an Ercoupe. BUT you still need to feed it with a pump. Lots of  information in Coupe Capers the newsletter of EOC  www.ercoupe.org. Van's is working on the  tank of the new RV-12 located inside the cockpit too. www.vansaircraft.com     KABONG   

 [quote]   ---

craig(at)craigandjean.com
Guest

Posted: Sun Mar 18, 2007 7:15 pm Post subject: Fuel tank selector

One thing I don't like about a conventional header tank in  a low wing plane is the fact that you need working electric fuel pumps to fill  it from the wing tanks. A magneto-based engine will run with no electrical input  but not those fuel pumps. So if you loose your electrical system you have to get  to a safe landing sport with what is in your header tank. If it is a small  header tank or the pumps need to be manually cycled to fill it then that may not  be a lot of fuel.

  

 -- Craig

   [quote][b]

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