Thorp Air Command - T18.net

Supporting Owners, Builders and Pilots of the Thorp T-18 and its variants.
It is currently Tue Oct 15, 2019 4:52 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 5 posts ] 
Author Message
Ryan Allen
 Post subject: Fuel Expansion question
PostPosted: Thu Jul 25, 2019 6:33 am 
Sr. Member
Sr. Member
User avatar

Joined: Wed Oct 21, 2009 6:10 pm
Posts: 824
Images: 0
Location: Louisiana
here is my setup. I have wing tanks that gravity flow to a fuel pump under the pilots feet. From that pump, the fuel is pumped up into the main tank. Each wing tank has its own vent out of each wing. The main tank of course has a vent too. I get overboard venting out of the wing vents just after takeoff when full and it streaks fuel down the underside of the wing, which I then have to clean up.

Please check my thinking regarding fuel expansion: If I put a one way check valve on the wing tank vents so that air can only come into the tank, wouldn't the wing tank fuel expand up through the fuel lines, through the electric pump in the cockpit, and into/out of the main tank vent?


Top
 Profile Personal album  
 
Jeff J
PostPosted: Thu Jul 25, 2019 4:10 pm 
Sr. Member
Sr. Member

Joined: Wed Aug 31, 2016 8:18 am
Posts: 486
Images: 0
Location: eastern OK
I agree with your thinking on expansion. I don’t think you are likely to vent extra from the main tank unless you already vent from the wings as the fuel heats up. I use to fly an Air Tractor that vented fuel in flight. Never saw it vent fuel on the ground. The boss’s Skyhawk does the same thing when the left tank is full.

_________________
Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson


Top
 Profile Personal album  
 
James Grahn
PostPosted: Thu Jul 25, 2019 7:19 pm 
Hero Member
Hero Member

Joined: Sat Oct 24, 2009 7:16 pm
Posts: 1116
Images: 0
Location: USA
I wouldn’t put a check valve in there. You might actually pressurize something you don’t want to. Wing tanks can vent pretty easily. Just make sure the line goes up and forward before it exits the wing. Also, have the vent opening facing into the wind. I met some guys that make the vent line do a few loops before exiting, but I’m really not a fan of that.
Cubes


Top
 Profile Personal album  
 
Ryan Allen
PostPosted: Thu Jul 25, 2019 9:44 pm 
Sr. Member
Sr. Member
User avatar

Joined: Wed Oct 21, 2009 6:10 pm
Posts: 824
Images: 0
Location: Louisiana
yes, it does vent really easily. I cant stand it. I appreciate the tips. I've tried up and forward and loops. I do have the vent facing forward with a 45 degree angled face. Loops seem to work best, but still get too much venting during flight. No venting on the ground. First world problems I guess....


Top
 Profile Personal album  
 
Jeff J
PostPosted: Fri Jul 26, 2019 6:01 pm 
Sr. Member
Sr. Member

Joined: Wed Aug 31, 2016 8:18 am
Posts: 486
Images: 0
Location: eastern OK
The Skyhawk vents forward to a forward facing tube. Riding the rudder in the Skyhawk or the 502 will stop it on them.

Cubes is correct (of course). Accidentally pressurizing a fuel tank would be bad. A wet wing starts getting as wet outside as it is inside kind of bad. If you install check valves make sure pressure can’t build up in the tanks.

_________________
Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson


Top
 Profile Personal album  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


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 post attachments in this forum

Search for:
Jump to:  
cron

[ Time : 0.047s | 12 Queries | GZIP : On ]