Hi All, It?s been a while since I?ve been on the newsletter betweenwork and trying
to make progress on the Long EZ.
Anyway, it?stimefor the Fuel system and I wanted to get feedback from thegroup onmy
design. I attached a PDF of my concept whichutilizes 2different sumps, 1 rear
cockpit thigh support/fuelsump and a 2ndsump in the hell Hole. The reason for the
addedsumps is to try torecover some of the fuel I will be losingdue to installing
Infinityretractable gear.Anyway, myassumption was a P-Ported 13B with aTO4 turbo so
the linesneed to be able to keep that thirsty puppy humming at WOT. Iguess it would
make about 350hp at WOT. Anyway, can you guystake a look and shoot holes and make
recommendations. I lookat the fuel system and Engine installation design as
themostcritical systems we develop so I want it to be right.
Thanks
Mike C.
I'd put a fuel drain in the lowest part of each sump where lowest iswhen the ship
is parked.
I'd put the pumps in the last sump.
I don't see provision for fuel return.
tc
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Thanks TC, cant believe I forgot the return line. I decided to do away with the
Hell hole sump, seems like I would be creating a lot of work for little gain. I did
add a fitting to the thigh sump so Icould add an Aux Tank if it was ever needed.
Could just strap itinto the GIB seat. Anyway, I have a couple of questions about
thefuel return. Will it have enough pressure to overcome the headpressure in the
sumps from the Strake tanks? And the thigh sump isprobably only 2-3 Gallons so
should I be worried about hot fuel inthe sump? Or should I just return the fuel to
the strakes? If Ireturn it to the strakes is there a chance I could empty the
sumpfaster than the gravity fill line can return it to the sump? Thanksagain for all
the help guys. I attached an updated diagram, throw arrows!
Mike C.
Paul
I'm resending this because I never saw it posted, Might have gotten lost in the ether.
Thanks
Mike C.
Now you are talking my language as an instrument tech (industrial) . Why use cad
plated carbon steel fittings. This is designated by the single S prefix. I would use
either SS (stainless) there is a a couple of different stainless types available or
alloy. Also a couple of options. Use the SS ferrule sets. With time the cadmium
plating seems to let the nut stick to the fitting and it takes some effort to break
it loose. SS does not have the same problem. Its problem lies with a lack of
tolerance to cross threading. Proper tightening of the fittings is important. Start
with the nut just finger tight on the fitting and then tighten 1 1/4 turns. Use a
felt pen to mark it to get it right.Also, I would use 1/2" return line to make sure
there is no restriction there.What is the method of connecting to the sumps. You
show tube unions
(600-6) with the tube coming out of the sump. Another fitting available is
SS-6-TA-1-? i Left a question mark for the pipe thread size; 1/4,3/8, or 1/2"NPT.
These would be 4, 6, or 8 like AN designations. This would then allow the use of the
tube unions directly. A better option is SS-600-1-? tube adapter. If you need a
90* then SS-600-2-?. There is also 45* available. This would eliminate a possible
leak source or two. You know every joint will leak eventually.Swagelok has available
a small catalogue that is about 6" x 3" and about 3/8" thick that lists a lot of
this and explains the codes for it's fittings. Also pressure ratings for tubing
sizes and materials.
Dale
Hi Dale
Thanks for the info, I only chose the Steel because they were a lot cheaper, I'll
change to SS. I will also increase the size of the return line to 1/2". My plan is
to use Al tubing which will be floxed into the sumps and Swagelok fittings to
connect the lines toe the stub tubes in the sump. It seemed like a simple solution.
I did look at the Swagelok fittings with NTP -600-2 on one end but thought if I
used Al tubing I could bend the tubes in the sump to the location (lowest point for
the fuel feed and highest point for the fuel supply and vent) that they needed to be
at. Then flox them in place through the sump walls with a stub tub protruding which
will allow me to use a union to attach to the rest of the supply lines and vents.
Now that I think about it I could use a ss-600-2-8 for the return lines and a
SS-600-2-12 for the Sump feed and increase the feed line size to 3/4". Then use the
original plan for the fuel pick up lines to the Andair valve.Keep shooting arrows,
I really want a bullet proof Fuel System. No fuel = no thrust = BAD DAY!
Thanks
Mike C.
Hi Mike,
Another option for the lines instead of floxing them is to put a pipe fitting into
the tank as required. You can get bore through fittings from Swagelok. These do not
have the smaller bore down from the nut and ferrule area that stops the tube from
going farther through. If you put a 3/4" NPT fitting in the tank, you can put a
suction screen on a tube and have the tube bent to where you need the end at. Then
you slip the fitting over the tube and tighten the fitting in. Once the fitting(tube
adapter in Swagelok speak) is tight, you tighten the tube nut to lock the tube in
place. Then you can cut the tube off an inch from the nut and can then use a tube
union to connect to it. There is also available reducing unions. An example of the
part number for these is; SS-810-6-6. This would connect a 3/8" tube to a 1/2" tube.
Also there is Alloy fittings for different applications to deal with some
chemicals. Some of these may be lighter, but also more costly.
Once you finalize the fittings required you can contact the local Swagelok people
and compare the costs. I do not think the weight savings would be a lot, but a
kitchen scale would answer that quickly.
The fitting to put in the tanks are readily available for welding into pipe or thin
wall tanks made of sheet metal. Known as weld-o- let. To flox, protect the threads
and use a course sand blast to rough up the surface. Fiberglass tanks use this
method and have 2"
to 4" fittings with no problem. Grounding cables are commonly attached here also as
a stud can be welded to the fitting before glassing that the ground can be attached
on to. Very common in the oil patch for produced tanks to catch water. Of course
there is always some hydrocarbons with the water that could ignite with a static
build up.
Dale Davies
Hi Dale
Attached is the diagram for an Aluminum Sump, Can you check out the fittings I
identified to make sure they make sense? I thought a lot about it and I think Al is
the right way to go for the Sump. I can just cut out the parts and have them all
welded together and have the fittings welded on which will eliminate a possible leak
source.
It also solves any grounding issues.
Thanks
Mike C.
Hi Mike,
The fittings you specify are 90* weld in of Al construction. OK. The A-1210-C
should be changed to A-1210-P as the fitting is configured for a nut and ferrule.
The -C is to cap a tube that has a nut and ferrule on the end of it.
Next to consider is the flow capabilities. Straight or 90* fittings are drilled to
the same diameter, BUT the 90* introduces turbulence and thus a restriction to flow.
The fittings are drilled to a slightly smaller diameter than the tube ID of the
lightest tube wall available. A tube bend introduces much less turbulence than the
angle fitting. That said however, there should be no problem with 3/4" tube for
gravity feed to the sump. An A-1210-1-12W welded to the side at the top of the sump
would be better. The tube bend radius could be a problem if space is tight. Another
factor I found with light wall 2/3" tube is a bit of wrinkle imparted to the inside
of the bend. If I remember correctly, we somehow got some SS 3/4" x 0.035 tube that
did this.
Heavier wall tube corrected this.
Tube ID is the OD-(wall thickness x 2) so the ID gets smaller quickly as the wall
thickness gets thicker. 1/2" x 0.035 ID is 0.43" while 0.049 wall ID is 0.402".
For the suction to the pumps, coming out the side a bit above the sump bottom
allows water or dirt to stay there until drained out and helps keep the filters clean.
When bending the Al or any tube, a quality bender gives MUCH better bend quality.
The less expensive benders have a tendency to leave a small "crimp"
in the tube or scratch the outside. A bit of grease or anti-seize on the tube and
bend shoe helps prevent galling of the tube. I highly recommend the Swagelok
benders, however they are expensive. If you can rent some it will be to your
advantage or get someone who has a set to do the bending for you. The labor cost is
offset by the superior job and that person should have at least the 3/8" and 1/2"
benders. There is no Swagelok 3/4" bender so that can not be helped.
Dale Davies
Thanks Dale, Sorry for the late response, Work has been crazy. Anyway, I did look
at the A-1210-1-12W but space is tight and if I want the fittings on the side of the
tank I don't think I can make the bend in the 3/4" tub to make the turn for a
straight fitting. And your right those tube benders are expensive, Maybe I can find
someone that can loan me one when I get to the bending point.
Thanks
Mike C
Hey Mike,
Make sure that you use a mandrel bender to bend that tube. There's no way you can
make a tight radius bend without wrinkling up the inside of the bend if you don't use
a mandrel bender. I'm not suggesting that you buy a mandrel bender, or even rent
one. They are way expensive. Find a pipe shop that has one and pay them to make the
bends for you.
I understand that musical instrument makers fill their tubes with ice before they
bend them to avoid the wrinkled tubing syndrome. I've never tried it but I would
imagine that it would take some experimentation to get the technique down.
I've seen heavy duty coil springs sized to fit inside tubing to prevent the bend
distortion. I haven't tried these either so again some experimentation is in order.
Mandrel benders I've used and I know they work.
Mark LaPierre
Here is the tube bender I use.
Paul Lamar
Thanks Guys, I was going to try a hand bender 1st like the ones Paul suggested but
there aren’t a lot of 3/4" hand benders out there. If that doesn't work I will find
a shop that bends pipes.
Thanks
Mike C
3/4 is a bit big. 3/8 will flow a lot of fuel.
Make a test rig and put a 1 foot head on it.
Time the flow with a stop watch.
Paul Lamar
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