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gravity feed fuel system

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Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Oct 28, 2009 1:03 pm Post subject: gravity feed fuel system

All this talk of fuel system things brings to mind a thought I've had for 

some time, which wouldn't work on Kolbs with the engine on top would work 

on my UltraStar:  Mounting the fuel tank above the engine and using 

straight gravity feed (no pump at all).  I know I'd need a different float 

needle and seat but I'm unclear how much head is needed to get adequate flow.



Another idea would be a small header tank (1 gallon or so) above the engine 

and fill it from a larger, lower tank with an overflow returning the excess 

to the lower tank.  In the event of a pump failure I'd still have 15 

minutes or so to find a place to land.



-Dana

--

  The family that shoots together..... shouldn't be messed with!

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Wed Oct 28, 2009 1:12 pm Post subject: gravity feed fuel system

Dana, When my buddy, Dave, and I were flying our Kasperwing we tried that experiment. Tank above carb (Mikuni) about 1', Zenoah G 25 engine. Wouldn't flow enough fuel at full throttle. I have no idea why, it makes no sense, it just liked the little extra fuel pressure the Mikuni pump added. We actually tried it twice, convinced we had done something wrong the first time, but, same result. 



Rick Girard

do not archive



On Wed, Oct 28, 2009 at 4:03 PM, Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)> wrote:

 [quote]--> Kolb-List message posted by: Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)>

  

 All this talk of fuel system things brings to mind a thought I've had for some time, which wouldn't work on Kolbs with the engine on top would work on my UltraStar:  Mounting the fuel tank above the engine and using straight gravity feed (no pump at all).  I know I'd need a different float needle and seat but I'm unclear how much head is needed to get adequate flow.

  

 Another idea would be a small header tank (1 gallon or so) above the engine and fill it from a larger, lower tank with an overflow returning the excess to the lower tank.  In the event of a pump failure I'd still have 15 minutes or so to find a place to land.

  

 -Dana

 --

  The family that shoots together..... shouldn't be messed with!

 

 

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The smallest miracle right in front of you is enough to make you happy....

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Oct 28, 2009 1:36 pm Post subject: gravity feed fuel system

At 05:12 PM 10/28/2009, Richard Girard wrote:

 	  Quote: 	
		  Dana, When my buddy, Dave, and I were flying our Kasperwing we tried that 

experiment. Tank above carb (Mikuni) about 1', Zenoah G 25 engine. 

Wouldn't flow enough fuel at full throttle. I have no idea why, it makes 

no sense, it just liked the little extra fuel pressure the Mikuni pump 

added. We actually tried it twice, convinced we had done something wrong 

the first time, but, same result.


	


Did you change the float needle and seat?  There is a different (larger) 

needle/seat used for gravity feed systems.  The larger needle won't work 

for pump systems as the pressure pushes it open.



-Dana

--

  If ignorance is bliss, why aren't there more happy people?

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Wed Oct 28, 2009 3:00 pm Post subject: Re: gravity feed fuel system

Dana,



Your gravity feed system is not a good idea.  By putting an extra tank and lines above the engine from below, you increase your risk of fire, and a number of other things going wrong.   The best and safest way to approach this is again what Certified aircraft manufacturers do, which is to pressure feed your fuel from below with an electric pump to the engine driven pump.  The system should be designed so that either pump alone could keep the engine running.  Chances of having two pumps fail at once are nil, and you don't have all the hazards, and complication of what you are proposing.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Oct 28, 2009 3:33 pm Post subject: gravity feed fuel system

Your argument would make more sense if so many manufacturers of high wing 

aircraft didn't use gravity feed from tanks above the engine, and no fuel pump.



Over on the PPG lists, there has been a recurring discussion over the 

relative safety of tanks above vs. below the engine.  People scream about 

the fire dangers of high mounted tanks, but in reality the only fire that 

has ever happened with a high tank was when an oil soaked rag stuffed 

behind the exhaust caught fire and then ignited the tank... whereas there 

have been a number of fires after low mounted tanks got ruptured in a hard 

landing.



And an electric pump is only possible when you have a 12V electrical 

system, which I don't (nor did the Taylorcraft I used to own).



-Dana



At 07:00 PM 10/28/2009, JetPilot wrote:



 	  Quote: 	
		  Your gravity feed system is not a good idea.  By putting an extra tank and 

lines above the engine from below, you increase your risk of fire, and a 

number of other things going wrong.   The best and safest way to approach 

this is again what Certified aircraft manufacturers do, which is to 

pressure feed your fuel from below with an electric pump to the engine 

driven pump.  The system should be designed so that either pump alone 

could keep the engine running.  Chances of having two pumps fail at once 

are nil, and you don't have all the hazards, and complication of what you 

are proposing.


	


--

  Daddy, why doesn't this magnet pick up this floppy disk?

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Wed Oct 28, 2009 3:44 pm Post subject: gravity feed fuel system

No, While the folks at Tennessee Propeller were helpful, they seemed to be less knowledgeable about the engines than they were about making the engine and propeller work. If there was a different needle valve they never mentioned it. 



Rick Girard

do not archive



On Wed, Oct 28, 2009 at 4:30 PM, Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)> wrote:

 [quote]--> Kolb-List message posted by: Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)>

  



 At 05:12 PM 10/28/2009, Richard Girard wrote:

  	  Quote: 	
		   Dana, When my buddy, Dave, and I were flying our Kasperwing we tried that experiment. Tank above carb (Mikuni) about 1', Zenoah G 25 engine. Wouldn't flow enough fuel at full throttle. I have no idea why, it makes no sense, it just liked the little extra fuel pressure the Mikuni pump added. We actually tried it twice, convinced we had done something wrong the first time, but, same result.

  	
 



 Did you change the float needle and seat?  There is a different (larger) needle/seat used for gravity feed systems.  The larger needle won't work for pump systems as the pressure pushes it open.

 

 -Dana

 --

  If ignorance is bliss, why aren't there more happy people?



 

 

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 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

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[b]

_________________
The smallest miracle right in front of you is enough to make you happy....

WhiskeyVictor36(at)aol.co
Guest

Posted: Wed Oct 28, 2009 4:37 pm Post subject: gravity feed fuel system

In a message dated 10/28/2009 5:13:09 P.M. Eastern Daylight Time,  aslsa.rng(at)gmail.com writes:

   	  Quote: 	
		     Dana, When my buddy, Dave, and I were flying our Kasperwing we    tried that experiment. Tank above carb (Mikuni) about 1', Zenoah G 25 engine.    Wouldn't flow enough fuel at full throttle. I have no idea why, it makes no    sense, it just liked the little extra fuel pressure the Mikuni pump added. We    actually tried it twice, convinced we had done something wrong the first time,    but, same result.

    

   Hi all,

    

   Here's something to consider.  Motorcycles don't    use a fuel pump (at least the older ones that I rode didn't) and their    fuel tanks are only inches above the engine/carburetors, yet they didn't seem    to have a problem with gravity fuel flow.

    

   Bill    Varnes

Original Kolb FireStar

Audubon NJ

Do Not  Archive

	


  [quote][b]

russkinne(at)mac.com
Guest

Posted: Wed Oct 28, 2009 4:52 pm Post subject: gravity feed fuel system

Mike 	  Quote: 	
		  Have you perhaps forgotten that all small Cessnas -- BTW, a "Certified aircraft manufacturer" -- have gravity-fed fuel systems? Backed up sometimes by both mechanical and electrical fuel pumps.And for how many decades has this been working just fine?  On Cessnas, Stinsons, Taylorcraft, Luscombes, Norsemen, Otters. Beavers, etc etc. 	
  Perhaps no one ever told Clyde Cessna that it wasn't a good idea.

  do not archive

bill_joe(at)bellsouth.net
Guest

Posted: Thu Oct 29, 2009 2:06 am Post subject: gravity feed fuel system

And almost farm  tractors have gravity feed fuel system, if not all. At least I have never seen  one with a pump..

  

       Bill  Futrell

  

     Do Not Archive...

 [quote]   ---

pj.ladd(at)btinternet.com
Guest

Posted: Thu Oct 29, 2009 6:41 am Post subject: gravity feed fuel system

The system should be designed so that either pump alone could keep the 

engine running.  Chances of having two pumps fail at once are nil, and you 

don't have all the hazards, and complication of what you are proposing.



    Tank above, tube in the middle, carburettor below. No pump.  What is 

complicated.?



Haven`t noticed many lawnmowers bursting into flame recently.

Cheers



Pat

slyck(at)frontiernet.net
Guest

Posted: Thu Oct 29, 2009 7:10 am Post subject: gravity feed fuel system

Even with multiple electric pumps, when that 12VDC goes away you  

better start looking for a good spot.

BB



On 29, Oct 2009, at 10:39 AM, pj.ladd wrote:



 	  Quote: 	
		   



 The system should be designed so that either pump alone could keep  

 the engine running.  Chances of having two pumps fail at once are  

 nil, and you don't have all the hazards, and complication of what  

 you are proposing.



   Tank above, tube in the middle, carburettor below. No pump.  What  

 is complicated.?



 Haven`t noticed many lawnmowers bursting into flame recently.

 Cheers



 Pat

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Thu Oct 29, 2009 11:35 am Post subject: Re: gravity feed fuel system

 	  russkinne(at)mac.com wrote: 	
		    Perhaps no one ever told Clyde Cessna that it wasn't a good idea.

  do not archive 	




Russ and Dana,



I never said that a gravity fed system was not a good idea...   I said that running fuel tubing from the bottom tanks of a Kolb to an EXTRA tank on top of the engine on a Kolb as Dana described is a bad idea, and most definitely an added fire hazard.   



Dana's other configuration idea, which is to mount the main fuel tank on a Kolb above the level of the engine is also just as hazardous, draggy, and not practical in an aircraft where the engine is the highest part of the plane.  



Both these scenarios are very different from having gravity fed wing tanks in a Cessna.   I personally think these two individuals are just looking for any way possible to discredit anything I post here, even if they know they are being dishonest in their comparisons and conclusions.  If these two individuals honestly did not understand these basic concepts, and posted these bad comparisons in error, they certainly are not qualified to be giving technical advice on airplanes.   Either way makes them very non credible posters.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

williamtsullivan(at)att.n
Guest

Posted: Thu Oct 29, 2009 3:42 pm Post subject: Gravity feed fuel system

Mike- Dana has an Ultrastar.  The engine is mounted very low, and if only one tank is used a gravity feed looks like it would probably work.  I think it's the only Kolb model with the engine mounted under the boom tube.  It looks like a dragonfly.

  

                                        Bill Sullivan

                                        Windsor Locks, Ct.

                                        FS 447

 [quote][b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Thu Oct 29, 2009 4:13 pm Post subject: gravity feed fuel system

At 03:35 PM 10/29/2009, JetPilot wrote:

 	  Quote: 	
		  ...running fuel tubing from the bottom tanks of a Kolb to an EXTRA tank on 

top of the engine on a Kolb as Dana described is a bad idea, and most 

definitely an added fire hazard.



Dana's other configuration idea, which is to mount the main fuel tank on a 

Kolb above the level of the engine is also just as hazardous, draggy, and 

not practical in an aircraft where the engine is the highest part of the 

plane.


	


Obviously you didn't bother to read my entire message.  I fly an UltraStar, 

which has the engine BELOW the wing, with plenty of room for a tank above 

the engine.  I wasn't proposing it for any other Kolb model.  I'm not so 

stupid as to think that it would make sense for an aircraft with the engine 

at the highest point.



 	  Quote: 	
		  ...I personally thing these two individuals are just looking for any way 

possible to discredit anything I post here...


	


No, only the things you say that are wrong, or show that you haven't 

bothered to read the message you're responding to.



-Dana



--

  For every new foolproof invention there is a new and improved fool.

russkinne(at)mac.com
Guest

Posted: Thu Oct 29, 2009 4:52 pm Post subject: gravity feed fuel system

There you go again.

On Oct 29, 2009, at 3:35 PM, JetPilot wrote:



 	  Quote: 	
		   

 russkinne(at)mac.com wrote:

>   Perhaps no one ever told Clyde Cessna that it wasn't a good idea.

>   do not archive

 Russ and Dana,



 I never said that a gravity fed system was not a good idea...   I  

 said that running fuel tubing from the bottom tanks of a Kolb to an  

 EXTRA tank on top of the engine on a Kolb as Dana described is a  

 bad idea, and most definitely an added fire hazard.



 Dana's other configuration idea, which is to mount the main fuel  

 tank on a Kolb above the level of the engine is also just as  

 hazardous, draggy, and not practical in an aircraft where the  

 engine is the highest part of the plane.



 Both these scenarios are very different from having gravity fed  

 wing tanks in a Cessna.   I personally thing these two individuals  

 are just looking for any way possible to discredit anything I post  

 here, even if they know they are being dishonest in their  

 comparisons and conclusions.  If these two individuals honestly did  

 not understand these basic concepts, and posted these bad  

 comparisons in error, they certainly are not qualified to be giving  

 technical advice on airplanes.   Either way makes them very non  

 credible posters.



 Mike



 --------

 &quot;NO FEAR&quot; -  If you have no fear you did not go as fast  

 as you could have !!!



 Kolb MK-III Xtra, 912-S





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 70007#270007

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Fri Oct 30, 2009 7:57 am Post subject: gravity feed fuel system

>>Dana's other configuration idea, which is to mount the main fuel tank on 

a

 	  Quote: 	
		  >Kolb above the level of the engine is also just as hazardous, draggy, and 

>not practical in an aircraft where the engine is the highest part of the 

>plane.



 Obviously you didn't bother to read my entire message.  I fly an 

 UltraStar,

 >
	


 	  Quote: 	
		   -Dana


	




Dana/Gang:



In the beginning the Ultrastar had two Azusa go kart fuel tanks of  1.75 gal 

each for a grand total of 3.5 gal.  Was just enough fuel to get me in 

trouble in 1984.



The area above the engine mount was ideal for a third 1.75 gal tank, which I 

ordered from Little Mike at Kolb and promptly mounted, using Adel clamps and 

a couple aluminum tubes.  Now I had 5.25 gal total.  The top tank was my 

reserve tank.  When the fuel in the bottom two tank got low enough for the 

contents of the reserve tank, I opened a valve at my right hand and drained 

the fuel.



There was no additional drag created by addition of the third tank.  The 

pilot in the Ultrastar completely mask the engine and the reserve fuel tank.



This system worked like a charm, was safe, and never had a n on  board fire, 

although I had two serious accidents with the Ultrastar.



john h

mkIII

Death Valley, CA

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Fri Oct 30, 2009 8:55 am Post subject: gravity feed fuel system

At 11:45 AM 10/30/2009, John Hauck wrote:



 	  Quote: 	
		  In the beginning the Ultrastar had two Azusa go kart fuel tanks of  1.75 

gal each for a grand total of 3.5 gal.  Was just enough fuel to get me in 

trouble in 1984.



The area above the engine mount was ideal for a third 1.75 gal tank, which 

I ordered from Little Mike at Kolb and promptly mounted, using Adel clamps 

and a couple aluminum tubes.  Now I had 5.25 gal total.  The top tank was 

my reserve tank.  When the fuel in the bottom two tank got low enough for 

the contents of the reserve tank, I opened a valve at my right hand and 

drained the fuel.


	


Exactly what I have, except my reserve tank is 1.5 gallons mounted behind 

the seat.  Obviously gravity is enough to feed fuel to the lower tank far 

faster than the engine draws it; I'm just concerned with how fast gravity 

will push it past the float needle... I'll have to check; there's probably 

a spec for the required height when using the gravity flow needle.



My interest in a 5 gallon tank is twofold:  Reliability (no fuel pump), and 

the space currently occupied by the main tanks can be used as a small 

storage area.



-Dana

--

  Why is it called tourist season if we can't shoot at them?

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Oct 30, 2009 9:55 am Post subject: Re: gravity feed fuel system

 	  Dana wrote: 	
		  Your argument would make more sense if so many manufacturers of high wing 

aircraft didn't use gravity feed from tanks above the engine, and no fuel pump.



	




Dana,



There is a HUGE difference between mounting a header tank or a fuel tank on the top of a Kolb Ultrastar and expecting it to gravity feed the engine,  and using gravity feed from Wing tanks down to the carburetor on a tractor type airplane ( Cessna etc. ).  The vertical distance from the tank to the carb on the setup you describe is very short, probably too short for RELIABLE gravity feed to the carb.   Sounds like an accident waiting to happen, I hope you don't hurt yourself. 



The distance from wing tanks down to the bottom of the engine where the carb is located on a certified airplane is 3 or 4 times the vertical drop, supplying much more fuel pressure.   So no, there is no comparison between what you propose and the system that Cessna, or other certified airplanes use.



You and and Russ stated  " Certified airplanes use gravity feed systems, so you don't know what you are talking about... "     In reality there is really no comparison between the Kolb and Cessna here...  I stand by my previous posts.  Let us know how it works for you.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

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