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05-29-2011, 12:52 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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RV-3: Fuel Lines for the IO-320
Thanks to Tom Swearengen of TS-Flightlines, we now have all of the firewall forward fuel lines we needed to hook up our new TMX-IO320 in the RV-3! This was by no means a ?stock? installation (there is no such thing for an RV-3, or an experimental engine), and without a FWF kit, we were pretty much on our own to figure out how to make it work. Fortunately, we didn?t run into anything that couldn?t be covered with standard techniques and practices, so it was mostly a matter of figuring out good lengths, hose ends, and routings. I generally like to build my own fluid line when doing a ?custom? installation, because I can get the lengths exactly right by attaching one end, then measuring ?in place? to attach the other. I?ll do that with the oil lines for this plane, as they are fairly straightforward, but for the fuel lines, I wanted to try the newer style ?brown? sealed fire sleeve, and since we already had one such line that came with the engine it only made sense to make a matching set. (The engine came with two lines, one from the pump to the servo, the other from the servo to the flow divider. Unfortunately, we had to change the servo from a left-feed to a right-feed to make the mixture arm work right with the RV FAB, so the ?short? line was no longer appropriate)
Because the fuel injection system is not certified (Precision Silverhawk) on this engine, I was already in ?experimental? territory with the powerplant, so I decided to design and fabricate my own bracket and location for the fuel flow sensor, putting it between the Servo and Flow Divider, rather than further upstream in the ?airframe? part of the system. This has been shown to provide a more accurate measure of fuel flow than when the flow transducer is closer to the fuel pumps ? while not essential, it is ?nice?. I consulted with Mahlon at Mattituck about a good location for the ?Red Cube?, and he said that on certified aircraft, it is frequently put between the servo and the divider as well, so this made it more attractive. Of course, the fact that the RV-3 is so compact made it impossible to find a good place to put the ?red Cube? anywhere between the fuel selector and the engine driven pump made the decision easier as well. With the straight-pipe (non-cross-over) exhaust, the front of the oil sump was wide open, so I built a bracket from 4130 steel that mounted to two sump bolts and gave a very solid and straight mounting plate for the cube.
Once the flow transducer was in place, it was a simple matter to decide on the four total hoses we needed between the firewall and the flow divider, figure out a natural routing, and pick appropriate ends (straight, 45?s, 90?s, etc). To clear the throttle arm and linkage, Tom suggested a ?long drop? 90 degree fitting fabricated from stainless steel that has been used on similar installation, and after consultation with a couple of engine builders, this sounded like a good plan to me as well. I measured hose lengths for Tom using a piece of nylon static system tubing that seemed to like to bend at approximately the same radius as the fuel lines we were using, holding it up between the various end fittings, then measuring the resulting lengths. The line from the firewall to the engine-driven pump was made a little long to give it a little bit of an S-curve to allow for movement. In the pictures shown, I have not added final Adel clamps and rub-point restraints, so if you see a ?hey, that?s going to abrade!? spot, I probably already know about it. I generally run a fuel system with my hands touching the lines from end to end to find places that need restraint and/or protection.
Firewall to fuel pump:
Fuel Pump to Fuel Servo:
Servo to Flow Transducer and on to the Flow Divider (around the back of Cylinder #4):
You?ll notice that I took pains to caveat a few things about this being an ?experimental? installation on an ?experimental? engine. With those considerations comes the burden of understanding that there can always be surprises, and it will take some flight testing and rigorous inspection in the early days of the airplane?s life to make sure that we don?t have a vibration or wear problem. I doubt that we?ll be taking this Single-Engine airplane into conditions where the loss of that engine would be catastrophic until we have done a significant amount of diligent testing to confirm that our designs are satisfactory in this regard.
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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05-31-2011, 07:44 AM
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Join Date: Jun 2006
Location: Roanoke, Texas
Posts: 76
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Monkey
Looking good Paul!
Is it ok to mount the ff transducer solid to the engine? I thought they want it suspended between fuel hoses with the wires on top.
Also, looks like the hose clamp may be out of place on the #1 intake hose.
__________________
Randy Richmond
A&P, IA, Private Pilot
RV Builder
Owner:Richmond Aircraft Service
11563 Airway Blvd.
Roanoke, TX 76262
(52F)
817-401-809six
Inspections, Prebuys, Builder assistance,
Damage Repairs, Ferry Services
Last edited by Monkey : 05-31-2011 at 07:49 AM.
Reason: added text
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05-31-2011, 11:43 AM
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Join Date: Jan 2006
Location: Belgium
Posts: 645
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Vibration!!
Paul, Like monkey said: I also think that the fuel flow sensor should not be attached to the engine, because virbation will destroy it, or make it inaccurate.
I also installed the (Dynon) fuel flow sensor between the servo and the "spider". But I have about 100 mm of straight hose between the servo and the sensor (actually exactly like you have the hose, going up towards the sensor, but mine is straight) and than from the sensor, with a big bent, between Cylinders 1 and 3 to the flow devider. So the sensor is sort of left of the servo, under/in front of the oil pan (seen from the front). That is a shorter route (less hose, less weight) and leaves the sensor suspended from the hoses, free of engine vibration.
I covered the sensor with a large dia. firesleave.
I must admit, the Dynon fuel flow sensor is a lot less bulky and probably a lot lighter, than the red box you have got.
My fuel flow reading is dead steady and seems to be very accurate.
Regards, Tonny.
__________________
"Pilottonny"
Tonny Tromp
Lanaken, Belgium (EU)
RV9A, Registration: PH-VAN
ECI-Titan IOX-320 with dual EI, turning a Whirlwind 200RV CS prop.
Sold
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05-31-2011, 11:55 AM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Hey Randy, thanks! I read the instructions that came from the red cube, and it gave three different acceptable ?up? positions ? wires up, access plate (with multiple screws) up, or outlet up. I didn?t really like just hanging that weight without restraint in the fuel line, and checked with a couple of engine guys (including Mahlon) who didn?t see a problem with a bracket, and in fact said there are numerous installations on spine bolts. I know of several installations that have a lot of hours mounted to brackets on the sump bolts, and some on the spine, near the flow divider. The remaining question is if there might be a vibration that drives the sensor nuts, which I think is Tonny's point, in which case I could always remove the bracket and let it hang. I will have to give this a little thought before committing to run it - the red cubes aren't cheap. Both are good inputs.
Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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05-31-2011, 12:21 PM
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Join Date: Apr 2010
Location: Ridgeland, SC
Posts: 2,589
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Paul-
reference to Tonny's vibration post----maybe, remove the bracket, and make 2 hose brackets that attach Adel clamps to the hoses a couple of inches away from the cube.
But---Lee Logan's Rocket has the red cube mounted to a bracket, clamped to a rear tube on the engine mount, and plumbed between the fuel pump and the servo. I havent heard him complain about inaccurate readings.
I guess testing is the real answer. IF we need to modify the hoses, no issue.
Tom
__________________
Tom Swearengen, TS Flightlines LLC, AS Flightlines
Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com, www.asflightlines.com
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05-31-2011, 12:52 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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I like the idea of two Adel clamps off the sump bolts as an alternative - it would certainly give a different stiffness to the mount, and I have seen a number of red cubes mounted with a single Adel clamp so that they don't move around. the problem, of course, is that we don't really know what stiffness we want to prevent damage to the cube and give accurate readings. As I said - good things to think about, and it is accessible if I decide to make a change at anytime.
Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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05-31-2011, 05:17 PM
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Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,574
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fuel line conflict with engine baffles?
Hi Paul,
Where your line runs up behind the #4 cylinder to the divider, isn't there a cooling baffle that occupies some of that real estate? Or do the cheek-cowled engines cool differently?
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 625
LS6-15/18W sailplane SOLD
bought my old LS6-A back!! 
VAF donation Jan 2020
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05-31-2011, 05:39 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Quote:
Originally Posted by scsmith
Hi Paul,
Where your line runs up behind the #4 cylinder to the divider, isn't there a cooling baffle that occupies some of that real estate? Or do the cheek-cowled engines cool differently?
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Yes, No, and (like everything else in the -3), it is going to be very tight....
I did a few preemptive measurements on a couple of other planes, and I am pretty confident it will fit, but just barely. You'll notice that the line has not yet been secured, as it might change positions a little bit before e tie it down. A backup plan is to go INSIDE the engine mount then through the rear baffle between the left LORD mount and centerline. In the worst case, I can flip the entire Spider assembly over from left to right, and go around that way, but I am optimistic at this point.
Building a -3 is a new adventure every day, with emotions running from triumph to tragedy and back again.
Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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06-01-2011, 10:58 AM
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Join Date: Feb 2007
Location: colorado
Posts: 873
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curious
Building a -3 is a new adventure every day, with emotions running from triumph to tragedy and back again.
What makes building an RV-3 different than what many of us did with the RV-4 20 years ago? Thats what I remember the most: " highs and lows" of trying to figure out how to do the FWF without having all of the premade parts and very few chances to see what others had done in that area. The manual even had a statement to the effect that the FWF is left to the builders descretion because of the many variables. I think I spent as much time looking at it and thinking about it as I did actually doing it, if not more.
just curious
cm
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06-01-2011, 03:54 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Quote:
Originally Posted by Christopher Murphy
What makes building an RV-3 different than what many of us did with the RV-4 20 years ago? Thats what I remember the most: " highs and lows" of trying to figure out how to do the FWF without having all of the premade parts and very few chances to see what others had done in that area. The manual even had a statement to the effect that the FWF is left to the builders descretion because of the many variables. I think I spent as much time looking at it and thinking about it as I did actually doing it, if not more.
just curious
cm
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I suspect that building a -4 20 years ago was very similar Chris - and there was no Internet community (to speak of) to go to for help. I ave looked at current -4 drawings, and they are a bit more complete and sophisticated than those for the -3, but I have no idea what they looked like back then.
I guess I was speaking to the vast majority of current builders who are workign on much more sophisticated kits than folks had back then - heck, they even have kits and drawings for the FWF now!
Paul
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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