M20F-1968 Posted April 12, 2019 Report Share Posted April 12, 2019 Let me try to clarify my question: I have a 1968 F model which originally had 32 gallons per side with two fuel senders per side, one mounted inside the fuselage wall and one on the outboard end of the fuel tank. I then add the Monroy tanks which use a bay further outboard, and connect by gravity alone to the outboard end of the main tanks. When you fill the main tanks there is a point that some of the fuel spills into the Monroy tanks, When this occurs, the main tank is not yet completely full. When the main tank is completely filled to the top of the main tank filler, there is more than 32 gallons in the plane, as some of the fuel has spilled into the Monroy tank. You then cap off the main tank. To complete the filling process you open the Monroy gas cap and fill the Monroy tank. If you open the main tank when the Monroy tank is completely full, you will see some spillage from the main tank open filler port. The Monroy tanks add 15 gallons per side since I also have speed brakes. The full tank, main + Monroy should be 47 gallons per side which is exactly what I put into my right tank when I ran it nearly dry to the JPI final fuel warning. The engine did not stop at that point but I am sure I was very close to the unusable fuel limit ( certainly close enough for my purposes). I tried to calibrate the senders based on fuel added. So in my case I tried to use 11 gallons per 1/4 tank, thus: 1/4 = 11 gallons 1/2 = 22 gallons 3/4 = 33 gallons full = 47 gallons (simply adding the 3 gallons to the top 1/4 of the tank) Given that the Monroy tanks hold 15 gallons, there is expected to be not much difference between completely full and 3/4 full as indicated on the JPI, but there should be a slight change given that when the first 15 gallons is being burned off, most of that 15 gallons should come from the Monroy tanks, but because the Monroy tanks are connected to the mains, some should come from the main tank as well. At 33 gallons (on one side) there should be some fuel in the Monroy tanks, and some fuel should be burned off of the main tank given that fluid seeks it own level. I can not tell you what the distribution actually is. However, when one calibrated the JPI 930 to the gallons added, the JPI should recognize a nonlinear curve when the last 1/4 tank is added. Likewise, when the Monroy tank is completely emptied, the JPI should recognize a more straight-line curve (influenced by the shape of the main tank) that is representative of the original 32 gallon main tank. The 25% tank warning seems to be approximately correct as the JPI is programmed at the 25% point (which is defined as 11 gallons), but it may report 25% based on the 25% movement of the float (25% of the movement min to max) and that 25% may in fact be advising of 8 gallons remaining since the main tank was originally 32 gallons. To complicate matters further, my wing site gauges show about 15 gallons when the 25% warning is given. It is difficult and time consuming to drain (or burn off fuel) to empty and then calibrate each 1/4 tank. I think, knowing that 47 gallons is very close to usable fuel, I fill the tank completely, burn off 14 gallons, then 11 gallons, then 11 gallons, then 11 gallons based on the fuel totalizer, and at each check point turn off the JPI, turn back on so the calibration screen shows the necessary readings for that fuel level, and create the paper chart while flying on smooth air in level flight. Your thoughts are welcomed. John Breda Quote Link to comment Share on other sites More sharing options...
Andy95W Posted April 12, 2019 Report Share Posted April 12, 2019 7 hours ago, Hyett6420 said: Andrew (aka the replusive one). Hey, that's not fair- you're not the only repulsive Andrew here! I am too, in my own way! 1 Quote Link to comment Share on other sites More sharing options...
Marauder Posted April 12, 2019 Report Share Posted April 12, 2019 Let me try to clarify my question: I have a 1968 F model which originally had 32 gallons per side with two fuel senders per side, one mounted inside the fuselage wall and one on the outboard end of the fuel tank. I then add the Monroy tanks which use a bay further outboard, and connect by gravity alone to the outboard end of the main tanks. When you fill the main tanks there is a point that some of the fuel spills into the Monroy tanks, When this occurs, the main tank is not yet completely full. When the main tank is completely filled to the top of the main tank filler, there is more than 32 gallons in the plane, as some of the fuel has spilled into the Monroy tank. You then cap off the main tank. To complete the filling process you open the Monroy gas cap and fill the Monroy tank. If you open the main tank when the Monroy tank is completely full, you will see some spillage from the main tank open filler port. The Monroy tanks add 15 gallons per side since I also have speed brakes. The full tank, main + Monroy should be 47 gallons per side which is exactly what I put into my right tank when I ran it nearly dry to the JPI final fuel warning. The engine did not stop at that point but I am sure I was very close to the unusable fuel limit ( certainly close enough for my purposes). I tried to calibrate the senders based on fuel added. So in my case I tried to use 11 gallons per 1/4 tank, thus: 1/4 = 11 gallons 1/2 = 22 gallons 3/4 = 33 gallons full = 47 gallons (simply adding the 3 gallons to the top 1/4 of the tank) Given that the Monroy tanks hold 15 gallons, there is expected to be not much difference between completely full and 3/4 full as indicated on the JPI, but there should be a slight change given that when the first 15 gallons is being burned off, most of that 15 gallons should come from the Monroy tanks, but because the Monroy tanks are connected to the mains, some should come from the main tank as well. At 33 gallons (on one side) there should be some fuel in the Monroy tanks, and some fuel should be burned off of the main tank given that fluid seeks it own level. I can not tell you what the distribution actually is. However, when one calibrated the JPI 930 to the gallons added, the JPI should recognize a nonlinear curve when the last 1/4 tank is added. Likewise, when the Monroy tank is completely emptied, the JPI should recognize a more straight-line curve (influenced by the shape of the main tank) that is representative of the original 32 gallon main tank. The 25% tank warning seems to be approximately correct as the JPI is programmed at the 25% point (which is defined as 11 gallons), but it may report 25% based on the 25% movement of the float (25% of the movement min to max) and that 25% may in fact be advising of 8 gallons remaining since the main tank was originally 32 gallons. To complicate matters further, my wing site gauges show about 15 gallons when the 25% warning is given. It is difficult and time consuming to drain (or burn off fuel) to empty and then calibrate each 1/4 tank. I think, knowing that 47 gallons is very close to usable fuel, I fill the tank completely, burn off 14 gallons, then 11 gallons, then 11 gallons, then 11 gallons based on the fuel totalizer, and at each check point turn off the JPI, turn back on so the calibration screen shows the necessary readings for that fuel level, and create the paper chart while flying on smooth air in level flight. Your thoughts are welcomed. John Breda John - where is your second sender located?Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
Marauder Posted April 12, 2019 Report Share Posted April 12, 2019 Let me try to clarify my question: I have a 1968 F model which originally had 32 gallons per side with two fuel senders per side, one mounted inside the fuselage wall and one on the outboard end of the fuel tank. I then add the Monroy tanks which use a bay further outboard, and connect by gravity alone to the outboard end of the main tanks. When you fill the main tanks there is a point that some of the fuel spills into the Monroy tanks, When this occurs, the main tank is not yet completely full. When the main tank is completely filled to the top of the main tank filler, there is more than 32 gallons in the plane, as some of the fuel has spilled into the Monroy tank. You then cap off the main tank. To complete the filling process you open the Monroy gas cap and fill the Monroy tank. If you open the main tank when the Monroy tank is completely full, you will see some spillage from the main tank open filler port. The Monroy tanks add 15 gallons per side since I also have speed brakes. The full tank, main + Monroy should be 47 gallons per side which is exactly what I put into my right tank when I ran it nearly dry to the JPI final fuel warning. The engine did not stop at that point but I am sure I was very close to the unusable fuel limit ( certainly close enough for my purposes). I tried to calibrate the senders based on fuel added. So in my case I tried to use 11 gallons per 1/4 tank, thus: 1/4 = 11 gallons 1/2 = 22 gallons 3/4 = 33 gallons full = 47 gallons (simply adding the 3 gallons to the top 1/4 of the tank) Given that the Monroy tanks hold 15 gallons, there is expected to be not much difference between completely full and 3/4 full as indicated on the JPI, but there should be a slight change given that when the first 15 gallons is being burned off, most of that 15 gallons should come from the Monroy tanks, but because the Monroy tanks are connected to the mains, some should come from the main tank as well. At 33 gallons (on one side) there should be some fuel in the Monroy tanks, and some fuel should be burned off of the main tank given that fluid seeks it own level. I can not tell you what the distribution actually is. However, when one calibrated the JPI 930 to the gallons added, the JPI should recognize a nonlinear curve when the last 1/4 tank is added. Likewise, when the Monroy tank is completely emptied, the JPI should recognize a more straight-line curve (influenced by the shape of the main tank) that is representative of the original 32 gallon main tank. The 25% tank warning seems to be approximately correct as the JPI is programmed at the 25% point (which is defined as 11 gallons), but it may report 25% based on the 25% movement of the float (25% of the movement min to max) and that 25% may in fact be advising of 8 gallons remaining since the main tank was originally 32 gallons. To complicate matters further, my wing site gauges show about 15 gallons when the 25% warning is given. It is difficult and time consuming to drain (or burn off fuel) to empty and then calibrate each 1/4 tank. I think, knowing that 47 gallons is very close to usable fuel, I fill the tank completely, burn off 14 gallons, then 11 gallons, then 11 gallons, then 11 gallons based on the fuel totalizer, and at each check point turn off the JPI, turn back on so the calibration screen shows the necessary readings for that fuel level, and create the paper chart while flying on smooth air in level flight. Your thoughts are welcomed. John Breda John - where is your second sender located?Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
M20F-1968 Posted April 12, 2019 Report Share Posted April 12, 2019 My second sender in in its original location, on the outboard wall of the main tank. John Breda Quote Link to comment Share on other sites More sharing options...
Marauder Posted April 12, 2019 Report Share Posted April 12, 2019 My second sender in in its original location, on the outboard wall of the main tank. John Breda I think what you are going to find is that no matter how much fuel you have in the Monroy tank, it will show full until you burn down to a level where the outboard sender begins to move. Which with the original 64 gallon system, is 32 gallons. The way to prove this is looking at the calibration values on the JPI when you are beyond 32 gallons. The sender will be pegged at the top of the outer tank and no matter how much fuel you put in the Monroy, the calibration factor will remain the same.I may be missing something but I don’t think it can read anything in the Monroy tank.Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
M20F-1968 Posted April 12, 2019 Report Share Posted April 12, 2019 2 minutes ago, Marauder said: I think what you are going to find is that no matter how much fuel you have in the Monroy tank, it will show full until you burn down to a level where the outboard sender begins to move. Which with the original 64 gallon system, is 32 gallons. The way to prove this is looking at the calibration values on the JPI when you are beyond 32 gallons. The sender will be pegged at the top of the outer tank and no matter how much fuel you put in the Monroy, the calibration factor will remain the same. I may be missing something but I don’t think it can read anything in the Monroy tank. Sent from my iPad using Tapatalk Pro Chris: You are essentially correct. The JPI will only see the summation of the ohms of the two senders. +30 ohms when the inboard sender is fully raised, and then + 0 --> 30 additional as the outboard sender is raised. The issue is how much fuel goes into the Monroy tanks in the last 1/4 of the tank when topped off. I suspect that both tanks are being filled at some point and say 10 gallons when near full will show some movement of the float, but there will not be anywhere near the same deflection (and changes in ohms) as when the lower 1/2 (main tank is filled). I just do not know what that curve looks like yet. I am sure it is much flatter, but do not know yet if it is undetectable. John Breda Quote Link to comment Share on other sites More sharing options...
Marauder Posted April 12, 2019 Report Share Posted April 12, 2019 Chris: You are essentially correct. The JPI will only see the summation of the ohms of the two senders. +30 ohms when the inboard sender is fully raised, and then + 0 --> 30 additional as the outboard sender is raised. The issue is how much fuel goes into the Monroy tanks in the last 1/4 of the tank when topped off. I suspect that both tanks are being filled at some point and say 10 gallons when near full will show some movement of the float, but there will not be anywhere near the same deflection (and changes in ohms) as when the lower 1/2 (main tank is filled). I just do not know what that curve looks like yet. I am sure it is much flatter, but do not know yet if it is undetectable. John Breda I now get where you are going with this. Have you tried to call José and ask if this is happening? I think it would be something that had to be asked during his certification process. Do you have a physical drawing how the factory and the extended tanks are laid out? I can’t imagine much could be cross filling into the Monroy from the main filler port. But your comment that not much comes out when you main filler port with the Monroy filled has me curious how that can happen.Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
carusoam Posted April 14, 2019 Report Share Posted April 14, 2019 Some Monroy installations are more complex than others... If your fuel floats didn’t move when the extended volume got added, that is worth calling José about to get a better solution for your particular challenge... Some owners added the extra volume, but only cared about where the zero line was really at... Owners today can and want to get accuracy from top to bottom... Being a digital solution... the Cies gauges have the ability to handle non linear challenges... hence the two gallon increments discussed... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
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