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GPI bladder fuel tanks

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Firedog(at)visi.com
Guest

Posted: Sun Mar 17, 2013 2:46 pm Post subject: GPI bladder fuel tanks

Yaksters...

 

Kelley Monroe and I just installed a set of GPI bladder fuel tanks in my CJ.  We are now at the fuel level calibration stage.  My interpretation of the 'dialing in" instructions suggest that the pilot will only be able to tell how much fuel is in each tank(s) when their respective levels are below 63 litres...and that the gauge will not show or display the full 113 litre or 30 gallon available.  How have the rest of you (~50 kits sold to date) addressed this problem?  Send the fuel gauge out to be renumbered? Ignore the lack of real time fuel consumption data and stay cool until the needle starts to move off the "6"?  Please give me some guidance.

All the best,

Robert

N6343U

MIC based...Minnesota...home of the cold and untanned!    

 

 

Dr. Robert A. Schroeder

Schroeder Fire Inc.

612.922.2349

 

  [quote][b]

wlannon(at)shaw.ca
Guest

Posted: Sun Mar 17, 2013 6:07 pm Post subject: GPI bladder fuel tanks

From your numbers the bladder holds 36 litres more than the standard  tank.   The fuel level sending unit is a float type and senses the  vertical position of the fuel surface.   The fuel guage shows a  maximum of 60 litres in the standard tank (probably because that is the maximum  travel of the float arm in that particular sending unit) and with it installed  in the larger tank it will also show 60 litres when the fuel surface is at the  same height.   The actual fuel quantity in the bladder will be  something more than 60 litres.   Whatever that number is it will  represent the maximum guage reading for that particular system.  

  

 It would be necessary to calibrate the system by adding fuel in 5 (or 10?)  litre increments and noting the guage reading for each increment.    With that information a calibration card could be produced showing the actual  fuel quantity for each guage reading.   That information could also be  used to fabricate a new dial plate for the guage.

  

 In any case I doubt that the sending unit range is adequate to read the  full fuel quantity.

  

 Walt

  

 PS:   I note your spelling is in proper accordance with the  Kingâ€™s English!!!!!!

  

  

  From:  Dr. Robert  Schroeder (Firedog(at)visi.com) 

   Sent: Sunday, March 17, 2013 3:44 PM

 To: yak-list(at)matronics.com (yak-list(at)matronics.com) 

 Subject: GPI bladder fuel tanks

  



   

Yaksters... 

  

Kelley Monroe and I just installed a set of GPI bladder fuel  tanks in my CJ.  We are now at the fuel level calibration stage.  My  interpretation of the 'dialing in" instructions suggest that the pilot will only  be able to tell how much fuel is in each tank(s) when their respective levels  are below 63 litres...and that the gauge will not show or display the full 113  litre or 30 gallon available.  How have the rest of you (~50 kits sold to  date) addressed this problem?  Send the fuel gauge out to be renumbered?  Ignore the lack of real time fuel consumption data and stay cool until the  needle starts to move off the "6"?  Please give me some  guidance. 

All the best, 

Robert 

N6343U 

MIC based...Minnesota...home of the cold and  untanned!     

  

  

Dr. Robert A. Schroeder 

Schroeder Fire Inc. 

612.922.2349 

 

[quote]



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[b]

jan.mevis(at)informavia.b
Guest

Posted: Sun Mar 17, 2013 11:17 pm Post subject: GPI bladder fuel tanks

We installed Dennis' fuel bladders in our Yak 52. It is great, having an

additional 50 extra liters.

But for the fuel senders: the bladders are deeper, so the first 8

centimeters (more or less, I don't remember exactly) are not measured.

When the indicators are in the red, there's still some 40 liters on board.

This also means that there's no simple linear and accurate modification, so

we think about installing a fuel flow meter.

Then the fuel gauges merely serve as a quick check.



Jan



PS: the installation of these fuel bladders has been discussed with the

Yakovlev Design Bureau, and they did not see any problem because nothing

changed on the balance.

The only limitation is that we must not do any aerobatics with more than 120

liters of fuel. 

But it is not an "officially "accepted modification by YDB.

As far as I know, they will never officially accept a foreign modification.



From:  Walter Lannon <wlannon(at)shaw.ca>

Reply-To:  "yak-list(at)matronics.com" <yak-list(at)matronics.com>

Date:  Monday 18 March 2013 03:04

To:  "yak-list(at)matronics.com" <yak-list(at)matronics.com>

Subject:  Re: GPI bladder fuel tanks



 	  Quote: 	
		  From your numbers the bladder holds 36 litres more than the standard tank.

The fuel level sending unit is a float type and senses the vertical position
	


of the fuel surface.   The fuel guage shows a maximum of 60 litres in the

standard tank (probably because that is the maximum travel of the float arm

in that particular sending unit) and with it installed in the larger tank it

will also show 60 litres when the fuel surface is at the same height.   The

actual fuel quantity in the bladder will be something more than 60 litres.

Whatever that number is it will represent the maximum guage reading for that

particular system. 

 

It would be necessary to calibrate the system by adding fuel in 5 (or 10?)

litre increments and noting the guage reading for each increment.   With

that information a calibration card could be produced showing the actual

fuel quantity for each guage reading.   That information could also be used

to fabricate a new dial plate for the guage.

 

In any case I doubt that the sending unit range is adequate to read the full

fuel quantity.

 

Walt

 

PS:   I note your spelling is in proper accordance with the King¹s

English!!!!!!

 

 

From: Dr. Robert Schroeder <mailto:Firedog(at)visi.com>

Sent: Sunday, March 17, 2013 3:44 PM

To: yak-list(at)matronics.com

Subject: GPI bladder fuel tanks

 

Yaksters...

 

Kelley Monroe and I just installed a set of GPI bladder fuel tanks in my CJ

tjyak50

Joined: 31 May 2007
Posts: 81
Location: Phoenix, AZ

Posted: Mon Mar 18, 2013 5:57 am Post subject: Re: GPI bladder fuel tanks

The indicating system is not a simple resitance value to the indicator? 



If it was you could use parallel or series resistors to make the needle show full / empty then reface the indicator. 



It may be a different type or I guess this would already have bewn tried.

jan.mevis(at)informavia.b
Guest

Posted: Mon Mar 18, 2013 6:18 am Post subject: GPI bladder fuel tanks

The Yak fuel gauge system is quite sophisticated. It's made by the

military for the military.

I think that someone described it some time ago on this list. (Rob ?).



Jan



On 18/03/13 14:57, "tjyak50" <tomjohnson(at)cox.net> wrote:



 	  Quote: 	
		  



The indicating system is not a simple resitance value to the indicator?



If it was you could use parallel or series resistors to make the needle

show full / empty then reface the indicator.



It may be a different type or I guess this would already have bewn tried.





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=396463#396463

tjyak50

Joined: 31 May 2007
Posts: 81
Location: Phoenix, AZ

Posted: Mon Mar 18, 2013 6:39 am Post subject: Re: GPI bladder fuel tanks

Jan I think we are talking only about the Nanchang fuel indicating system, which is different from the Yak fuel indicating system on account of its an indigenous design.

dsavarese0812(at)bellsout
Guest

Posted: Mon Mar 18, 2013 6:55 am Post subject: GPI bladder fuel tanks

The CJ bladders which were referred to in the original post use a 

totally new fuel sender.  Unlike the Yak 52 bladders which use the 

original fuel senders.  The CJ6 fuel senders do require calibration for 

both full and a low fuel level determined by the owner/installer.  

Therefore, the tanks will have to be filled and then drained down to the 

low level desired and the potentiometers set on the fuel senders.

Fuel instruments are not intended to be precise fuel remaining 

indicators, just like in automobiles with Full, 3/4, 1/2, 14, Empty 

marks.  These instruments show approximately how much fuel remains in 

the tank.  Once the new CJ fuel senders are calibrated, the pilot knows 

the approximate amount of fuel remaining in the tank by 1 - reading the 

fuel instrument and 2 - by the light coming on which the owner/installer 

set during the calibration. Lets say 15 liters.

If one wants a more accurate reading, then I always recommend installed 

a JPI FS450G fuel flow instrument (or similar instrument), calibrating 

the K factor during the first 4-5 fill ups, and now one will know within 

a couple of  tenths of a liter how much fuel has been used and how much 

fuel remains in the tanks, plus of course instant fuel flow based on the 

current power setting.

Dennis

A. Dennis Savarese

334-285-6263

334-546-8182 (mobile)

www.yak-52.com

Skype - Yakguy1

On 3/18/2013 9:15 AM, Jan Mevis wrote:

 	  Quote: 	

 The Yak fuel gauge system is quite sophisticated. It's made by the

 military for the military.

 I think that someone described it some time ago on this list. (Rob ?).

 Jan

 On 18/03/13 14:57, "tjyak50" <tomjohnson(at)cox.net> wrote:

> 

>

> The indicating system is not a simple resitance value to the indicator?

>

> If it was you could use parallel or series resistors to make the needle

> show full / empty then reface the indicator.

>

> It may be a different type or I guess this would already have bewn tried.

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p=396463#396463

>

>

jan.mevis(at)informavia.b
Guest

Posted: Mon Mar 18, 2013 7:14 am Post subject: GPI bladder fuel tanks

Sorry, I missed the line of the topic.



Jan



On 18/03/13 15:39, "tjyak50" <tomjohnson(at)cox.net> wrote:



 	  Quote: 	
		  



Jan I think we are talking only about the Nanchang fuel indicating

system, which is different from the Yak fuel indicating system on account

of its an indigenous design.





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=396471#396471

wlannon(at)shaw.ca
Guest

Posted: Mon Mar 18, 2013 8:27 am Post subject: GPI bladder fuel tanks

Hi Dennis;



I had assumed from Robert's post that he was considering re-calibration of 

the existing CJ6 fuel senders.   I was not aware that the bladders came with 

a new sending unit.



Walt



--

dsavarese0812(at)bellsout
Guest

Posted: Mon Mar 18, 2013 8:36 am Post subject: GPI bladder fuel tanks

Hi Walt,

Totally understand that.  Perfectly logical assumption.  If I did not 

know they came with new fuel senders, I would have assumed the same thing.

Dennis



A. Dennis Savarese

334-285-6263

334-546-8182 (mobile)

www.yak-52.com

Skype - Yakguy1



On 3/18/2013 11:23 AM, Walter Lannon wrote:

[quote] 



 Hi Dennis;



 I had assumed from Robert's post that he was considering 

 re-calibration of the existing CJ6 fuel senders.   I was not aware 

 that the bladders came with a new sending unit.



 Walt



 --

gill.g(at)gpimail.com
Guest

Posted: Mon Mar 18, 2013 9:44 am Post subject: GPI bladder fuel tanks

All



G&C CJ6 bladders are supplied with capitance fuel level sender probe which

provides accurate level measurement within its calibration range.  It

provides a resistance value in the circuit that the fuel gauge reads.  Not

all the fuel can be measured because of the dihedral wing in which the fuel

cavity is located.  The original metal tanks had the same measurement

limitation in that the first 15 liters were not measured by the float level

sender.  The recommended use for the senders in the bladders allows that the

additional are not measured and only the last 60 liters is measured because

that what CJ pilots are used to.  It is possible to reface the gauge to

reflect more of the fuel and calibrate the sender accordingly, but as the

system designer I have not checked the linearity of the gauge in its

response to the signal from the sender.  A quick look at the gauge face

suggests that the gauge is not totally linear in its response.  It would be

easier to install a digital gauge/display or do as Dennis suggests, all of

which are available.  Dennis' approach will account for all the fuel but not

by individual bladder.



Gill



--

dsavarese0812(at)bellsout
Guest

Posted: Mon Mar 18, 2013 10:51 am Post subject: GPI bladder fuel tanks

Now that is straight from the designer of the CJ bladders!  Thanks Gill.

Dennis



A. Dennis Savarese

334-285-6263

334-546-8182 (mobile)

www.yak-52.com

Skype - Yakguy1



On 3/18/2013 12:41 PM, Gill Gutierrez wrote:

[quote] 



 All



 G&C CJ6 bladders are supplied with capitance fuel level sender probe which

 provides accurate level measurement within its calibration range.  It

 provides a resistance value in the circuit that the fuel gauge reads.  Not

 all the fuel can be measured because of the dihedral wing in which the fuel

 cavity is located.  The original metal tanks had the same measurement

 limitation in that the first 15 liters were not measured by the float level

 sender.  The recommended use for the senders in the bladders allows that the

 additional are not measured and only the last 60 liters is measured because

 that what CJ pilots are used to.  It is possible to reface the gauge to

 reflect more of the fuel and calibrate the sender accordingly, but as the

 system designer I have not checked the linearity of the gauge in its

 response to the signal from the sender.  A quick look at the gauge face

 suggests that the gauge is not totally linear in its response.  It would be

 easier to install a digital gauge/display or do as Dennis suggests, all of

 which are available.  Dennis' approach will account for all the fuel but not

 by individual bladder.



 Gill



 --

N13472(at)aol.com
Guest

Posted: Mon Mar 18, 2013 11:59 am Post subject: GPI bladder fuel tanks

I have had Gill's  tanks and level senders for seven  years. My recommendation is leave the gauge

alone

after modifying the wiring per the instructions and calibrating the Capacitance sender the accuracy

is outstanding

far better than any span can I have ever owned. When I pull into the gas pit 98% of the time I can

tell within +- 1 gallon

how much fuel it will take to top off. I have checked this over several hundred hours of operation.



As to calibration as you only need to set the full and empty points leave the senders out of the

tank and

 get beaker jar or a tall flower vase fill with fuel and you can very quickly Cal. and verify the

sender.  



Without the pain in the ass of draining and filling the tanks several times.



  

Tom Elliott

CJ-6A NX63727

777 Quartz Ave

PMB 7004

Sandy Valley NV

89019

Cell 541-297-5497

N13472(at)AOL.COM



--

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