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601XL fuel tank baffles

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ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu Mar 15, 2007 12:33 pm Post subject: 601XL fuel tank baffles

Anyone think these are necessary? The plans don't call for it, but I've noticed in the NTSB accident reports that there were a fair number of accidents during approach where the plane stalled and crashed. I wouldn't be surprised if it was due to the plane possibly banking further than expected with half full tanks and helping tip the plane into a brief unexpected more drastic bank and then the ensuing panic. Anyone flying notice this tendency? Seems to me baffles are the way to go even though they're not specified. 80lbs of fuel (half tanks) in a 900lb plane (one passenger) sloshing over a few feet out on the wings would seem like it would be noticeable, especially at low airspeed in a low-wing.

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Thu Mar 15, 2007 1:12 pm Post subject: 601XL fuel tank baffles

If you keep your turns coordinated, there will be no sloshing of  

fuel. The only time the fuel might slosh around much is if you  

suddenly put the plane into a slip. I have used fairly substantial  

slips on some of my landings and have not had any problem maintaining  

roll control. The 601 has a lot of roll authority. I have a single  

set of the standard 12 gallon tanks. I have never noticed any  

behavior that might be attributable to fuel sloshing. I think baffles  

would just add unnecessary weight and complexity.

On Mar 15, 2007, at 4:33 PM, ashontz wrote:



 	  Quote: 	
		   



 Anyone think these are necessary? The plans don't call for it, but  

 I've noticed in the NTSB accident reports that there were a fair  

 number of accidents during approach where the plane stalled and  

 crashed. I wouldn't be surprised if it was due to the plane  

 possibly banking further than expected with half full tanks and  

 helping tip the plane into a brief unexpected more drastic bank and  

 then the ensuing panic. Anyone flying notice this tendency? Seems  

 to me baffles are the way to go even though they're not specified.  

 80lbs of fuel (half tanks) in a 900lb plane (one passenger)  

 sloshing over a few feet out on the wings would seem like it would  

 be noticeable, especially at low airspeed.


	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu Mar 15, 2007 1:22 pm Post subject: Re: 601XL fuel tank baffles

Food for thought.



How do you like the 2 12 gallon tanks? I kicked around the idea of the dual tanks in each wing for a total of 4 tanks.

 	  bryanmmartin wrote: 	
		  If you keep your turns coordinated, there will be no sloshing of  

fuel. The only time the fuel might slosh around much is if you  

suddenly put the plane into a slip. I have used fairly substantial  

slips on some of my landings and have not had any problem maintaining  

roll control. The 601 has a lot of roll authority. I have a single  

set of the standard 12 gallon tanks. I have never noticed any  

behavior that might be attributable to fuel sloshing. I think baffles  

would just add unnecessary weight and complexity.

On Mar 15, 2007, at 4:33 PM, ashontz wrote:



 	  Quote: 	
		   



 Anyone think these are necessary? The plans don't call for it, but  

 I've noticed in the NTSB accident reports that there were a fair  

 number of accidents during approach where the plane stalled and  

 crashed. I wouldn't be surprised if it was due to the plane  

 possibly banking further than expected with half full tanks and  

 helping tip the plane into a brief unexpected more drastic bank and  

 then the ensuing panic. Anyone flying notice this tendency? Seems  

 to me baffles are the way to go even though they're not specified.  

 80lbs of fuel (half tanks) in a 900lb plane (one passenger)  

 sloshing over a few feet out on the wings would seem like it would  

 be noticeable, especially at low airspeed.



	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Thu Mar 15, 2007 2:00 pm Post subject: 601XL fuel tank baffles

I have over four hours endurance with reserve now. After four hours,  

it's time to land and take a short break to streach my legs anyway.  

With 48 gallons, I wouldn't even be able to carry a passenger as my  

plane is a bit on the heavy side. Of course you could always keep  

them empty until you need the range. I believe the standard kits now  

come with 16 gallon tanks for a total of 32. That's probably the way  

I'd go if I were building it now.



 	  Quote: 	
		   



 Food for thought.



 How do you like the 2 12 gallon tanks? I kicked around the idea of  

 the dual tanks in each wing for a total of 4 tanks.


	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

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

Tim Juhl

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

Posted: Thu Mar 15, 2007 3:51 pm Post subject: Re: 601XL fuel tank baffles

Zenith provides 15 gallon tanks as a $490 upgrade.



My 182 (which was indeed a heavier airplane) carried 240 pounds of fuel per side when full.  I never noticed any effects from fuel sloshing.  I did notice the need to adjust aileron trim if the fuel amounts in the tanks differed significantly.



Tim

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu Mar 15, 2007 4:24 pm Post subject: Re: 601XL fuel tank baffles

I'm building from plans, be interesting to see what the changes are,. Probably just movement of a nose rib.



 	  bryanmmartin wrote: 	
		  I have over four hours endurance with reserve now. After four hours,  

it's time to land and take a short break to streach my legs anyway.  

With 48 gallons, I wouldn't even be able to carry a passenger as my  

plane is a bit on the heavy side. Of course you could always keep  

them empty until you need the range. I believe the standard kits now  

come with 16 gallon tanks for a total of 32. That's probably the way  

I'd go if I were building it now.



 	  Quote: 	
		   



 Food for thought.



 How do you like the 2 12 gallon tanks? I kicked around the idea of  

 the dual tanks in each wing for a total of 4 tanks.



	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

Tim Juhl

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

Posted: Thu Mar 15, 2007 5:21 pm Post subject: Re: 601XL fuel tank baffles

To install the 15 gallon tanks you move NR 4 outboard and have to cut off the portruding "L" for the original location of NR 4.



Tim

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu Mar 15, 2007 6:06 pm Post subject: Re: 601XL fuel tank baffles

Thanks. What's the lengthwise dimension on the tank and the new position of the #4 rib?



 	  Tim Juhl wrote: 	
		  To install the 15 gallon tanks you move NR 4 outboard and have to cut off the portruding "L" for the original location of NR 4.



Tim

Trainnut01(at)aol.com
Guest

Posted: Fri Mar 16, 2007 1:54 am Post subject: 601XL fuel tank baffles

Andy

 I'm building from component kits and I ordered the 15 gallon  tanks with the wings. NR4 is not  moved during assembly in  my kit, it is left out completely. It wasn't  even included in the kit. Instructions said to cut the protruding part of  the "L" for NR4 off flush with the remaining portion. They stressed that I not  drill the rivets out of the spar. 

 Also I have seen several 601 wings built with two nose ribs turned web to  web and less than an inch apart. One of those I think was originally the NR4  (inboard) but the second one (outboard) is not in my kit either and there is no  provision for it. It is not shown in my plans.

 CJ

 601XL/Corvair

 Wings almost

 do not archive



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  [quote][b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Fri Mar 16, 2007 3:31 am Post subject: Re: 601XL fuel tank baffles

I'm building from plans. I'll probably replace NR4 with a hat. and move NR4 outboard of the new tank. That being the case, what's the width of your 15 gallon tank? I take it it's just a stretched version of the 12 gallon tank. I'll make a 15 gallon tank based on the 12 gallon profile and just add some length to it. That way I'll know where to move NR4 to on mine when I reposition it.



30 gallons seems like a good compromise to me. 48 seems like a bit much, plus with 48 I'm looking at 4 tanks instead of 2, which is more hassle, more potential problems due to 2 tanks being empty most of the time (probably not good to have to tanks tht hardly get used), and more fuel management when I'm actually using the tanks.



On the high end for an estimate of 5gph, that's 6 hours of fuel, plenty if I decide to make it into an IFR platform at some point in the future.



[quote="Trainnut01(at)aol.com"]Andy

 I'm building from component kits and I ordered the 15 gallon  tanks with the wings. NR4 is not  moved during assembly in  my kit, it is left out completely. It wasn't  even included in the kit. Instructions said to cut the protruding part of  the "L" for NR4 off flush with the remaining portion. They stressed that I not  drill the rivets out of the spar. 

 Also I have seen several 601 wings built with two nose ribs turned web to  web and less than an inch apart. One of those I think was originally the NR4  (inboard) but the second one (outboard) is not in my kit either and there is no  provision for it. It is not shown in my plans.

 CJ

 601XL/Corvair

 Wings almost

 do not archive



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   	  Quote: 	
		  [b]

Trainnut01(at)aol.com
Guest

Posted: Fri Mar 16, 2007 4:23 am Post subject: 601XL fuel tank baffles

Andy

 The factory installed "L" for NR4 using the factory 15 gal fuel tank is at  STA 1770.

 CJ

  

 do not archive



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  [quote][b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Fri Mar 16, 2007 5:39 am Post subject: Re: 601XL fuel tank baffles

Cool thanks. I think I'll make the 15 gallon tank instead. I'll move that L and install a new hat stiffener where it was originally located. They didn't move any other ribs did they. I guess that NR doesn't line up with any of the rear ribs. 



What's the actually length of your tank? I would assume that no other ribs moved so it should be just a matter of subtracting NR station at 1770 minus the next inboard NR for a rough length of the tank, no? The reason I'm asking for the length of the tank (or at leat the distance between the ribs it sit inside of) is because in case there were any of changes of rib locations, at least I'll no the length of the tank for it to be 15 gallons vs 12 gallons, assuming the side profile is the same, which I don't see any reason why it wouldn't be.



[quote="Trainnut01(at)aol.com"]Andy

 The factory installed "L" for NR4 using the factory 15 gal fuel tank is at  STA 1770.

 CJ

  

 do not archive



AOL now offers free email to everyone.  Find out more about what's free from AOL at AOL.com. 

   	  Quote: 	
		  [b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Fri Mar 16, 2007 5:41 am Post subject: Re: 601XL fuel tank baffles

This is with the 12 gallon tanks? I think I may go with the 15 gallon tanks seeing as how I'm still putting the wing together. I belive an IFR plane needs 4.5 hours plus reserve, so 30 gallons should meet that requirement.



 	  bryanmmartin wrote: 	
		  I have over four hours endurance with reserve now. After four hours,  

it's time to land and take a short break to streach my legs anyway.  

With 48 gallons, I wouldn't even be able to carry a passenger as my  

plane is a bit on the heavy side. Of course you could always keep  

them empty until you need the range. I believe the standard kits now  

come with 16 gallon tanks for a total of 32. That's probably the way  

I'd go if I were building it now.



 	  Quote: 	
		   



 Food for thought.



 How do you like the 2 12 gallon tanks? I kicked around the idea of  

 the dual tanks in each wing for a total of 4 tanks.



	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

Trainnut01(at)AOL.COM
Guest

Posted: Fri Mar 16, 2007 6:12 am Post subject: 601XL fuel tank baffles

Andy

 I'll measure those tanks when I get back to the house this afternoon and  contact you off list with the "Rest of the story" on my fuel tank saga.

 CJ

  

 do not archive



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  [quote][b]

Michael Valentine

Joined: 09 Jan 2006
Posts: 108

Posted: Fri Mar 16, 2007 6:12 am Post subject: 601XL fuel tank baffles

I bought my wing kit from another builder up the road and Zenith just removed it from my complete kit.  His wing kit was prepared in 2003 and had 4 nose ribs inboard of the tank.  His spar was built for two 12-gallon tanks in each wing.  I contacted Zenith about modifying it for one 15-gallon tank.  The end result was cutting the flange of the nose ribs blocking the longer tank (for me that was NR 5 & 6) and drilling out the hat stiffener at 1770.  I then installed two new nose ribs where the hat stiffener had been.  Those nose ribs do not line up with any rear ribs. 



Michael in NH



On 3/16/07, ashontz <ashontz(at)nbme.org (ashontz(at)nbme.org)> wrote:[quote] --> Zenith-List message posted by: "ashontz" <ashontz(at)nbme.org (ashontz(at)nbme.org)>



Cool thanks. I think I'll make the 15 gallon tank instead. I'll move that L and install a new hat stiffener where it was originally located. They didn't move any other ribs did they. I guess that NR doesn't line up with any of the rear ribs. 



What's the actually length of your tank? I would assume that no other ribs moved so it should be just a matter of subtracting NR station at 1770 minus the next inboard NR for a rough length of the tank, no? The reason I'm asking for the length of the tank (or at leat the distance between the ribs it sit inside of) is because in case there were any of changes of rib locations, at least I'll no the length of the tank for it to be 15 gallons vs 12 gallons, assuming the side profile is the same, which I don't see any reason why it wouldn't be. 



[quote="Trainnut01(at)aol.com"]Andy

 The factory installed "L" for NR4 using the factory 15 gal fuel tank is at  STA 1770.

 CJ



 do not archive



AOL now offers free email to everyone.  Find out more about what's free from AOL at  AOL.com (http://www.aol.com?ncid=AOLAOF00020000000339).



 	  Quote: 	
		   [b]


	




--------

Andy Shontz

CH601XL - Corvair

 www.mykitlog.com/ashontz



[b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Fri Mar 16, 2007 6:28 am Post subject: Re: 601XL fuel tank baffles

Ok, so leave the the four inside ribs (wing walk) and then the new tank 15 gallon tank extends from NR4 to the new NR5 which is where the hat is currently.



I don't have my plans here at work, but looking at http://zenithair.com/cad/6-W-0.dwf I'm assuming the new tank will extend to some between the stations for rear rib #5 and rear rib#6 (on the front side of the spar of course). This drawing doesn't show the hats but if I remember correctly there was a hat between RR5 and RR6. I'll move the hat from the current location and put it where the NR 5 and 6 are now and move NR 5 and 6 roughly to where the hat is currently for the 12 gallon tanks.



[quote="Michael Valentine"]I bought my wing kit from another builder up the road and Zenith just removed it from my complete kit.  His wing kit was prepared in 2003 and had 4 nose ribs inboard of the tank.  His spar was built for two 12-gallon tanks in each wing.  I contacted Zenith about modifying it for one 15-gallon tank.  The end result was cutting the flange of the nose ribs blocking the longer tank (for me that was NR 5 & 6) and drilling out the hat stiffener at 1770.  I then installed two new nose ribs where the hat stiffener had been.  Those nose ribs do not line up with any rear ribs. 



Michael in NH



On 3/16/07, ashontz <ashontz> wrote: 	  Quote: 	
		   --> Zenith-List message posted by: "ashontz" <ashontz>



Cool thanks. I think I'll make the 15 gallon tank instead. I'll move that L and install a new hat stiffener where it was originally located. They didn't move any other ribs did they. I guess that NR doesn't line up with any of the rear ribs. 



What's the actually length of your tank? I would assume that no other ribs moved so it should be just a matter of subtracting NR station at 1770 minus the next inboard NR for a rough length of the tank, no? The reason I'm asking for the length of the tank (or at leat the distance between the ribs it sit inside of) is because in case there were any of changes of rib locations, at least I'll no the length of the tank for it to be 15 gallons vs 12 gallons, assuming the side profile is the same, which I don't see any reason why it wouldn't be. 



[quote="Trainnut01(at)aol.com"]Andy

 The factory installed "L" for NR4 using the factory 15 gal fuel tank is at  STA 1770.

 CJ



 do not archive



AOL now offers free email to everyone.  Find out more about what's free from AOL at  AOL.com (http://www.aol.com?ncid=AOLAOF00020000000339).



 	  Quote: 	
		   [b]



	




--------

Andy Shontz

CH601XL - Corvair

 www.mykitlog.com/ashontz



[b]

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Fri Mar 16, 2007 8:11 am Post subject: 601XL fuel tank baffles

I usually average about 5 gallons per hour in cruise.

On Mar 16, 2007, at 9:41 AM, ashontz wrote:

 	  Quote: 	
		   This is with the 12 gallon tanks? I think I may go with the 15  

 gallon tanks seeing as how I'm still putting the wing together. I  

 belive an IFR plane needs 4.5 hours plus reserve, so 30 gallons  

 should meet that requirement.

 bryanmmartin wrote:

> I have over four hours endurance with reserve now. After four hours,

> it's time to land and take a short break to streach my legs anyway.

-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

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

Tim Juhl

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

Posted: Fri Mar 16, 2007 9:15 am Post subject: Re: 601XL fuel tank baffles

The 15 gallon tank measures 1270 mm end to end.   The "L" for the repositioned NR #4 is moved 260 mm outboard of where the "L" for the 12 gallon tanks was installed.  There is no rear rib behind it.  The factory built spars do not extend the aluminum bar that runs on the front of the spar top and bottom out to the new position of NR #4 - there is a hat stiffener between the old and new positions of NR#4 for a total of three behind the tank.  There are 7 nose ribs in all.



I've attached a pix taken of the bottom of the wing looking out from the wing root.



Tim

NoseRibs.jpg

Description:

Nose ribs (underside) viewed from wing root. Installed to accommodate 15 gallon tank.

Filesize:

72.06 KB

Viewed:

350 Time(s)

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Fri Mar 16, 2007 3:08 pm Post subject: Re: 601XL fuel tank baffles

Thanks for the info. That's all I needed.



 	  Tim Juhl wrote: 	
		  The 15 gallon tank measures 1270 mm end to end.   The "L" for the repositioned NR #4 is moved 260 mm outboard of where the "L" for the 12 gallon tanks was installed.  There is no rear rib behind it.  The factory built spars do not extend the aluminum bar that runs on the front of the spar top and bottom out to the new position of NR #4 - there is a hat stiffener between the old and new positions of NR#4 for a total of three behind the tank.  There are 7 nose ribs in all.



I've attached a pix taken of the bottom of the wing looking out from the wing root.



Tim

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