Thanks Thanks:  0
Likes Likes:  0
Results 1 to 32 of 32

Thread: fuel line ?

  1. #1

    Join Date
    Nov 2003
    Location
    wisconsin
    Posts
    79
    Post Thanks / Like

    fuel line ?

    When routing a headerless fuel system should all lines pitch downhill
    when plane is at 3pt (for H2o). I can get most lines to do that, but the
    right rear tank line is a little up hill when heading to the valve.
    The lines will plenty downhill when in flight.



    Building a Smith , Thanks Jon

  2. #2
    Crash's Avatar
    Join Date
    Apr 2002
    Location
    Nikiski Alaska
    Posts
    2,695
    Post Thanks / Like
    They should always go downhill towards the gasolator sump, how else is water going to make it to the sump. One of the problems with 3" extended gear and 31" tires is the front of these Cubs is getting so high, that on the ground the RH tank line doesn't feed down hill anymore. I'am surprised the FAA hasn't caught it yet. Crash

  3. #3

    Join Date
    Jun 2002
    Posts
    1,343
    Post Thanks / Like
    [delete

  4. #4

    Join Date
    Nov 2003
    Location
    wisconsin
    Posts
    79
    Post Thanks / Like
    Yep Crash its not looking good. With 26" rubber things just got worse,
    even routing the line high in the upper baggage area you cant get downhill to the valve. Im thinking of installing a tee and rear drain behind the baggage area, this looks to be the best solution.

    Jon

  5. #5
    Crash's Avatar
    Join Date
    Apr 2002
    Location
    Nikiski Alaska
    Posts
    2,695
    Post Thanks / Like
    Come off the rear fitting of the RH tank and stay high. The one obstical that forces the line down is the "D" window channel, but stay up as tight as possible to it. Forget the stock fuel line tabs, relocate them upwards where they are too low and keep the slope going. Both lines from the RH tank should slope to the "T" mounted just above the fuel selector in. Take care. Crash

  6. #6
    T.J.'s Avatar
    Join Date
    Apr 2002
    Location
    Alaska
    Posts
    3,211
    Post Thanks / Like
    I had the same problem when I put the left door in my XP. I put a "T" in the low point of the line at the rear of the passenger seat and a drain valve just inside of the left longeron.

  7. #7

    Join Date
    Nov 2003
    Location
    wisconsin
    Posts
    79
    Post Thanks / Like
    What are you using to bend alum. fuel line. The hardware store sells
    a tube bender and is listed for seel and copper but not alum. Will a
    simple spring bender work.

  8. #8
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    16,552
    Post Thanks / Like
    Spring bender works best for me because of all the weird bends around tubing etc. I have used the others but always resort back to the spring type on fuel lines.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  9. #9
    S2D's Avatar
    Join Date
    May 2002
    Location
    Montana
    Posts
    3,585
    Post Thanks / Like
    Which tubing is required in Supercub? 5052-0 , 3003-0 , or ? I just made up new tubes using 3003 versatube. then got to thinking might be too soft if you guys are talking about using tube benders on it. But I just "feel" tested the original tubing and seems to be the same properties as 3003.
    Never mind, its not worth it !!!

  10. #10

    Join Date
    Jun 2002
    Posts
    1,343
    Post Thanks / Like
    delete

  11. #11
    irishfield's Avatar
    Join Date
    Feb 2003
    Location
    Penetanguishene, Ontario Canada
    Posts
    2,868
    Post Thanks / Like
    Quote Originally Posted by diggler
    I use 5052 3/8 .035.
    Me to!..not to say you can't use the 3003...but I've always used 5052-0 x 3/8 x .035

  12. #12
    fatcub's Avatar
    Join Date
    Dec 2002
    Location
    Enumclaw, WA.
    Posts
    229
    Post Thanks / Like
    Will the 3/8" work for a o-360 install as well.

    Scott
    PA-12 Fat Cub

  13. #13
    irishfield's Avatar
    Join Date
    Feb 2003
    Location
    Penetanguishene, Ontario Canada
    Posts
    2,868
    Post Thanks / Like
    Can't state fact for the certified side of things...but 3/8" ..when smoothly fabricated... with proper size valves and fitting orfices generally produces over 25 to 35 GPH in fuel flow test on most high wings (sometimes more...and unfortunately sometimes less). To be legal you must have at least 150% of the engines max required fuel flow at take off power when gravity flow and 125% when running a pump. This is with the aircraft positioned in a max climb attitude (usually 15 to 18* nose high)...5 gallons in the tank and the fuel line removed at the carb (and including the strainer screen fitting). The line must be held at exactly the carb inlet height and the amount of fuel timed into a measured container to arrive at fuel flow. Anyone know max fuel flow on the O-360? O-320 is around 15.5 GPH so minimum fuel flow needed at test would be 23.25GPH

    Cheers,
    Wayne

  14. #14
    T.J.'s Avatar
    Join Date
    Apr 2002
    Location
    Alaska
    Posts
    3,211
    Post Thanks / Like
    delete

  15. #15
    T.J.'s Avatar
    Join Date
    Apr 2002
    Location
    Alaska
    Posts
    3,211
    Post Thanks / Like
    Original J3 fuel lines were 3SO which is the same as 3003.

  16. #16
    S2D's Avatar
    Join Date
    May 2002
    Location
    Montana
    Posts
    3,585
    Post Thanks / Like
    Just took a PA-11 apart had 2 tank system and all heavy copper lines. Wonder if that was legal? Guess it must have been, it flew for 35 yrs that way!
    Never mind, its not worth it !!!

  17. #17
    Jon B.'s Avatar
    Join Date
    Dec 2003
    Location
    Willmar, MN (KBDH)
    Posts
    712
    Post Thanks / Like
    The A&P/IA that I'm working with on my Champ project recently built a Super Cub from scratch (the owner bought a new fuse) for a customer. He used 5052 hard line for all the fuel lines and stated that the use of soft 3003 wasn't legal.

    I'm using 3003 on the Champ, as that's what came off it. Some of the lines on the original were copper, and one piece went back in - from the valve to the gascolator.

    Jon

  18. #18
    S2D's Avatar
    Join Date
    May 2002
    Location
    Montana
    Posts
    3,585
    Post Thanks / Like
    Quote Originally Posted by Jon B.
    He used 5052 hard line for all the fuel lines and stated that the use of soft 3003 wasn't legal.
    Jon
    Ask him why. Maybe he has Pipers specs. Univairs tubes are 5052, but they couldn't say what the original specs were. All the original I checked felt way too soft for 5052.
    Never mind, its not worth it !!!

  19. #19
    T.J.'s Avatar
    Join Date
    Apr 2002
    Location
    Alaska
    Posts
    3,211
    Post Thanks / Like
    delete

  20. #20

    Join Date
    Nov 2003
    Location
    wisconsin
    Posts
    79
    Post Thanks / Like
    What is Cub Crafters using for line size. Crash, what size line did you use?

  21. #21

    Join Date
    Jun 2002
    Posts
    1,343
    Post Thanks / Like
    delete

  22. #22

    Join Date
    Aug 2004
    Location
    Turkey
    Posts
    11
    Post Thanks / Like
    why not add another checklist item, "lift the tail 1', and drain the fuel line" ?

  23. #23
    KOZ's Avatar
    Join Date
    Nov 2003
    Location
    Grand Rapids, MI
    Posts
    60
    Post Thanks / Like

    Fuel line

    I have built 2 Smith cubs this year with 180'S and used 3/8th 5052 tubing with no problems. Both had 2 doors so the tubing had quite a long run from the rear port to the engine. Also built a Skybolt with an I0540 300Hp engine using 3/8th 5052. Almost vertical takeoff performance with no problems. Just stay away from the 2024 hard stuff.

  24. #24
    sekps's Avatar
    Join Date
    Jan 2002
    Location
    Lund, Sweden
    Posts
    314
    Post Thanks / Like
    For my headerless installation I used 3/8" 5052 and bent it with a simple tube bender from Sears.



    Worked like a charm!

    /Mattias

  25. #25
    Crash's Avatar
    Join Date
    Apr 2002
    Location
    Nikiski Alaska
    Posts
    2,695
    Post Thanks / Like
    Diggler is correct that both Cub Crafters and Penn Yan use 3/8" fuel line but require a "both" position on the fuel selector with a placard that states "Use Both for Take Off and Landings". They both also require pressure caps on the fuel tanks.

    I ran standard fuel caps for most of the summer (have a set of each). I tried everything I could to get the engine to starve for fuel and could not get it to even cough. Hard take off's on one tank, left and right. Radical manuvers on one tank or the other, and nothing. I did get it to quit when I ran on the right tank down to about 3 gallons then did a slow, coordinated steep turn with that wing low. Right at about 360 degrees the engine quit. Went to the Left tank, restarted the engine then back to the Right and flew level for some time before it was finally out. Take care. Crash

  26. #26

    Join Date
    Dec 2004
    Location
    Yarmouth, Nova Scotia
    Posts
    473
    Post Thanks / Like
    Not quite on the same topic but still fuel related, what type of line 1/8" o.d. is used on the primer line ? I see Aircraft Spruce advertises a polyurethane line, is this the line used? Also quite a difference in price for the primer pumps listed,is it worth the difference? I'm building a Smith's with a 0-360.
    Thanks Ron

  27. #27
    Crash's Avatar
    Join Date
    Apr 2002
    Location
    Nikiski Alaska
    Posts
    2,695
    Post Thanks / Like
    1/8" 2142 T1 .028 COPPER. Crash

  28. #28

    Join Date
    Dec 2004
    Location
    Yarmouth, Nova Scotia
    Posts
    473
    Post Thanks / Like
    Thanks Crash
    I didn't think plastic would be right but didn't see anything else listed. I'll locate some copper.
    Thanks again
    Ron

  29. #29
    S2D's Avatar
    Join Date
    May 2002
    Location
    Montana
    Posts
    3,585
    Post Thanks / Like
    Quote Originally Posted by Crash
    Diggler is correct that both Cub Crafters and Penn Yan use 3/8" fuel line but require a "both" position on the fuel selector with a placard that states "Use Both for Take Off and Landings". They both also require pressure caps on the fuel tanks.

    I ran standard fuel caps for most of the summer (have a set of each). I tried everything I could to get the engine to starve for fuel and could not get it to even cough. Hard take off's on one tank, left and right. Radical manuvers on one tank or the other, and nothing. I did get it to quit when I ran on the right tank down to about 3 gallons then did a slow, coordinated steep turn with that wing low. Right at about 360 degrees the engine quit. Went to the Left tank, restarted the engine then back to the Right and flew level for some time before it was finally out. Take care. Crash
    any theories why Crash?? Tank unporting? Design of system with more than one G ?? I was going to test the gravity theory on my way home today, to see if something would fall straight to the floor or hit a side window first in a turn, but everytime I let go of the object it would hit the skylight , then bounce around and bean me on the head Will try it on a calm day. Still don't think a tank will unport in a coordinated constant altitude turn, but I may be all washed up.
    Never mind, its not worth it !!!

  30. #30

    Join Date
    May 2002
    Location
    Minnesota
    Posts
    436
    Post Thanks / Like
    What size is the smallest opening in the entire fuel system from the tank to carb? Seems like this is going to determine how much flow you are going to get using gravity only. Will 1/2 line provide any more flow than 3/8 if the hole in the fuel valve shaft is the same size as the ID of 3/8 tube. Maybe CRASH or someone else knows what size the opening in the fuel valve is, and can tell us.

    Frank

  31. #31
    Alaska Cubs's Avatar
    Join Date
    Dec 2003
    Location
    American Falls, Idaho
    Posts
    35
    Post Thanks / Like
    This very topic was discussed a while ago on the Yahoo Stinson board when discussing the the use of the improved Allen 6S122 fuel selector valve, along with a JPI Fuel Scan 450. Both neck down to 3/8" while the 165 HP Stinsons' have 1/2" fuel lines. Bob H., an A&P and retired engineer wrote:
    One of the fundemental concepts in the study of viscous flow in pipes holds that: The resistance to flow caused by a restriction is proportional to the length of the restriction and inversly proportional to the cube of the diameter of the restriction. There is about 9 feet of fuel line in a Stinson 108 so changing the whole system from 3/8 in. to 1/2 in. tubing would reduce the resistance to flow by a factor of 2.4:1. Adding in 3 or 4 inches of 3/8 in. restriction only reduces the total improvement by about 4%. Hardly enough to get excited about.
    I hope this helps clear things up a bit.
    Merry Christmas!!
    Stan

  32. #32
    Crash's Avatar
    Join Date
    Apr 2002
    Location
    Nikiski Alaska
    Posts
    2,695
    Post Thanks / Like
    When you modify the fuel valve you use a 3/8" drill bit in the drill press. I am very picky and ream out all the ends I cut with a tubing cutter so they are not choked down. Any crimped tubing gets replaced. I would have to say it is pretty much 3/8" I.D. all the way through. The old Jensen STC required 1/2" tubing and looked like a real pain to work with. All of the fittings and ports in the gasolator are 3/8" anyway. The O-360 can't use that much more fuel then an O-320-B2B on take off so I don't see what the big deal is.

    The O-360 is just an O-320-B2B with the pistons moving 5/8" further up and down the cylinders. Crash

Similar Threads

  1. Aluminum Fuel Line
    By 747driver in forum Tips and Tricks
    Replies: 6
    Last Post: 08-18-2010, 10:41 PM
  2. Fuel line
    By pa19guy in forum Modifications
    Replies: 3
    Last Post: 08-31-2004, 12:30 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •