 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
Eric Page
Joined: 15 Feb 2017
Posts: 267
|
 Posted: Sat Feb 21, 2026 7:49 am Post subject: Re: Fuel System Manager |
 |
|
Here's a quick conceptual doodle showing how the switch wiring might be done to handle OFF-MANUAL-AUTO switching, using a 2TL1-1 (or, for a much cheaper alternative, the B&C S700-2-1).
Switched LPFS ground connection to be shared with HPFS using diode steering.
AFC logic remains the hurdle...
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
| Description: |
|
| Filesize: |
101.51 KB |
| Viewed: |
172 Time(s) |
|
|
|
| Back to top |
|
 |
911pete
Joined: 09 Aug 2018
Posts: 13
|
| Posted: Sat Feb 21, 2026 8:33 am Post subject: Re: Fuel System Manager |
|
|
Not being an electronics guy my question is would latching relays utilizing the fuel sensors be a path to control the logic?
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
user9253
Joined: 28 Mar 2008
Posts: 1958
Location: Riley TWP Michigan
|
| Posted: Sat Feb 21, 2026 8:40 am Post subject: Re: Fuel System Manager |
|
|
Pete, you wrote in a previous post, "The goal is to always keep the main tank
full until the wings are empty". That seems reasonable. It is hard for me to
understand how the fuel computer knows when to open and close the wing tank
valves when there are only two level sensors in the main tank, high and low. It
would not be desirable to let the main tank fuel level go down to the low level
sensor before opening the wing tank valves.
Suppose the computer closes the wing tank valves when the main tank is full.
As fuel is used, the high level sensor tells the computer that the main tank is no
longer full. The computer could then wait for a period of time, say 5 minutes,
before opening the wing tank valves again. That time delay period needs to be
short enough to keep the main tank relatively full. The time delay also needs to
be long enough so as not to wear out the solenoid valves due to short cycling.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
_________________
Joe Gores |
|
| Back to top |
|
|
911pete
Joined: 09 Aug 2018
Posts: 13
|
| Posted: Sat Feb 21, 2026 9:18 am Post subject: Re: Fuel System Manager |
|
|
I think you are mistaking where the low level sensor is. The main tank is approximately 75 gallons. The low level sensor is set at around the 60 gallon level. The plane burns 1.5 to 2 gallons per minute at non takeoff settings, so the valves would typically cycle every 7 to 10 minutes. If the fuel gets below the low level sensor for longer than 20 seconds the low level light would come on giving you around 30 minutes to land.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
user9253
Joined: 28 Mar 2008
Posts: 1958
Location: Riley TWP Michigan
|
| Posted: Sat Feb 21, 2026 11:28 am Post subject: Re: Fuel System Manager |
|
|
OK, I modified my drawing in post number 5 by moving the lower fuel level
sensor from the bottom of the tank to a higher position.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
_________________
Joe Gores |
|
| Back to top |
|
|
Eric Page
Joined: 15 Feb 2017
Posts: 267
|
| Posted: Sun Feb 22, 2026 6:37 am Post subject: Re: Fuel System Manager |
|
|
Pete, do you have a datasheet link for your LPFS and HPFS? I'd like to see their electrical requirements and what position feedback, if any, they offer.
Yes, latching relays could definitely be part of the solution, but they can't be driven directly by the fuel level sensors. This type of relay requires a brief pulse (a few tens of milliseconds) to set or reset its coil(s) (some have two), not a continuous current like a normal relay. This would require some electronics to turn the long-duration on/off cycles of the level sensors into these short pulses.
Also, we want the absence of fuel at the Low Level Sensor to open the solenoids, but we don't want them to close when that sensor sees fuel again; they have to wait until the High Level Sensor also sees fuel. That's going to require some electronics too.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
user9253
Joined: 28 Mar 2008
Posts: 1958
Location: Riley TWP Michigan
|
| Posted: Sun Feb 22, 2026 9:07 am Post subject: Re: Fuel System Manager |
|
|
Eric,
What do you think of the attached circuit? It uses discrete components. No computer necessary. Integrate it with your switch circuit.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
| Description: |
|
| Filesize: |
6 KB |
| Viewed: |
44 Time(s) |
|
_________________
Joe Gores |
|
| Back to top |
|
|
user9253
Joined: 28 Mar 2008
Posts: 1958
Location: Riley TWP Michigan
|
| Posted: Sun Feb 22, 2026 9:29 am Post subject: Re: Fuel System Manager |
|
|
After thinking about it, why use an AND Gate?
The upper liquid level switch could energize the relay.
The relay can hold through the lower liquid level switch.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
_________________
Joe Gores
Last edited by user9253 on Sun Feb 22, 2026 10:04 am; edited 1 time in total |
|
| Back to top |
|
|
user9253
Joined: 28 Mar 2008
Posts: 1958
Location: Riley TWP Michigan
|
| Posted: Sun Feb 22, 2026 9:48 am Post subject: Re: Fuel System Manager |
|
|
Simple relay circuit attached.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
| Description: |
|
| Filesize: |
5.55 KB |
| Viewed: |
28 Time(s) |
|
_________________
Joe Gores |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
