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Thread: Fuel Line

  1. #11

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    My Nieuport has an aluminum tank that sits right behind the firewall and over the pilot's legs simply because there is no place else to fit it.

    One of the factors in placement, of course, is flight parameters. In Champs, Cubs, and my little biplane the speeds and mass of the aircraft factor in with the safety of the decision if in a wreck.

    A wreck that involves enough force to actually make the tank a factor are already catastrophic to the point that it doesn't matter; the pilot has already been killed by the engine.

    Assuming less than a nose dive into the ground or full speed into a cliff, the airframe will take enough of the force that the fuel tank won't be touched. The lines and their routing, if prudent, should likewise be minor.

    A very neat thing about my plane's aluminum tube and gusset design is that it deforms very nicely. There's a video where a guy has his tail feathers cut clean off of his scaled Nieuport 11 by another plane at 100 feet AGL and does a nose dive into the grass; the pilot suffered a broken leg and soiled trousers.

    Steve, you're going to absolutely fall in love with the Champ! Mark One Eyeball Altimeter/Airspeed Indicator, Wind On Cheek/Butt Slide Slip Indicator, Sound and Vibration Tach systems are how it is meant to be.
    Last edited by Frank Giger; 02-26-2012 at 01:38 AM.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  2. #12
    rwanttaja's Avatar
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    Another factor to consider in the fuel-tank-in-the-cabin issue is whether putting it ELSEwhere might increase the potential for an accident.

    A Fly Baby might be a good example. Putting fuel tanks in the wings would be the only other option. But splitting one tank into two means the pilot now has the opportunity to mismanage the fuel valve and run one tank dry at the wrong moment. Putting the tanks in the low wings means that the airplane needs a fuel pump to get the gas to the engine. Another potential failure point.

    Remember, the P-51 had a fuel tank right behind the pilot...

    Ron Wanttaja

  3. #13
    steveinindy's Avatar
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    Remember, the P-51 had a fuel tank right behind the pilot...
    There's also the slight issue of a P-51 being a little more sturdily built than your average homebuilt. The fact that the thing had self-sealing tanks also mitigated the risk somewhat.

    But splitting one tank into two means the pilot now has the opportunity to mismanage the fuel valve and run one tank dry at the wrong moment.
    Point taken although there is the option of putting in a fuel pump which draws from both tanks simultaneously. Think a header tank effect without the header tank.

    Putting the tanks in the low wings means that the airplane needs a fuel pump to get the gas to the engine. Another potential failure point.
    What is the actual documented failure rate for a certified fuel pump that isn't due to improper maintenance, botched installation, etc? Has anyone actually looked into that? I'm not being argumentative, I am seriously curious about that. I've never seen any hard data on it.

    So far as I am concerned is offset by the benefit of the plane being less likely to turn turtle in a hard or forced landing scenario etc. I have a learned aversion to an aircraft with most of the mass above and/or behind the pilot(s) and passengers.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  4. #14
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    A wreck that involves enough force to actually make the tank a factor are already catastrophic to the point that it doesn't matter; the pilot has already been killed by the engine.
    Actually, you'd be damn surprised how many crash fatalities have NO traumatic injuries whatsoever other than their burns. Eliminating deaths due to smoke inhalation, burns and post-crash drowning (the three most common easily preventable causes of death in crashes or their immediate aftermath) would reduce GA aviation fatalities about 30-40%.

    It's a very common misconception that most crashes that kill people are utterly non-survivable. It's kind of the same attitude people had about car accidents (which at highway speeds frequently involve a similar amount of force when measured at the structure closest to the impact before the energy absorbing features have a chance to do their thing) in the 1950s and 1960s. If I had to put money on it, there are probably 1/5 to 1/4 of crashes (depending largely on the type of aircraft) that are going to kill everyone on board without question and there's little to do other than avoid them. The rest could have survival improved- although not assured- through some rather minor modifications to designs.

    The thing is that this is not a push to ground or force modifications to existing aircraft or even a criticism of them (well with a couple of major exceptions but that's a topic for another thread or for PMs). It's one of a desire to continue forward with the progression of technology at all levels of aircraft design. There are things that can be done in the Cub clone taildraggers, the RV series, the high performance boys like the Lancair and even the ultralight crowd. People grouse and moan about we don't respect where we have come from and the "spirit of homebuilding"- the creative, energetic and passionate spirit- is dead. It's not dead. Far from it as a matter of fact. The thing is that we just need a focus and a goal that can bring all of us together- from the ultralight junkies to the guys in the ultra-suped up Lancairs.

    I actually submitted a series of articles to Chad Jensen about this very subject and how the quickest way for us to get the NTSB and FAA off of our collective asses is to give them a reason to do exactly that. Trust me, as much as I catch crap on here for advocating for staying away from non-certified parts and such, the last thing I want is MORE oversight. The way we do this and the way I suggest a new goal for the creative and somewhat quixotic minds of experimental aviation to work together and stop bickering in a petty turf war of sorts is to make safety our focus.

    We are the only branch of aviation with sufficient leeway in the regs to pretty prove that safety and performance are not contradictory and that homebuilt aircraft are on par with anything coming out of the factories in Wichita, Duluth and elsewhere. Instead of being looked at as a bunch of weird folks who like to tinker in our garages and hangars (even thought a lot of us, myself included, are weird folks who like to tinker), let's use our collective experience, knowledge and creativity to figure out new ways to make better intrusion prevention, better restraints (lower rates of them separating from their mounts would be a great start), improved lightweight energy absorbing seats, better fuel tanks, etc.

    If we knock our fatal crash rate down by 10% through better construction in concert with continued pilot education, we have removed one of the major reasons for the FAA to scrutinize us like they have been doing lately. I believe this is an achievable and reasonable goal.

    Policing of our own ranks must also be part of our efforts. That is, putting your foot down and saying something when you see a fellow pilot about to do something stupid or after they've done something stupid but "gotten away with it". None of us wants to be a jerk or overstep our bounds but if we don't speak up to protect our brother and sister pilots and their passengers, who is going to do so in a way that we aren't going to hate a lot more?

    If anyone would like, I'm happy to provide a PDF of the medical records and autopsy report release form my research company uses to gain access to data for our crash safety research (for survivors and fatalities respectively). Handing one of those to a pilot about to do something boneheaded (like the guy I helped stop from taking off into freezing rain in a 172) tends to give someone pause.....especially if you hand one to his wife or other passengers as well. It's an option of last resort obviously but it generally make them rethink their cunning plan.


    Just my two cents....feel free to ream me for this post....
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  5. #15

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    Naw, no reaming...I can't disagree with any particular point.

    The crux is working the cost-benefits of design decisions, as all designs involve prudent compromises between safety and perfomance.

    Restraints are a great example, as you mentioned. I'll be spending a bit more in money and time than I really like on a five point restraint system because I view it as the first line of surviveability in a wreck. Since my plane is open cockpit, I'll be wearing a helmet during the first 40 and beyond; looking doofy in the cockpit is better than looking good in a casket.

    However, the location of the fuel tank is pretty much non-negotiable based on basic design and dimensions of the aircraft; installation and fuel line routing is going to be in the cockpit. That just means that a lot of attention to detail and foresight has to be put into them for safety.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  6. #16

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    Quote Originally Posted by Mike Clayton View Post
    I am trying to decide if there is any problem with use of flexible fuel line such as the Bing blue line ...I am looking for ideas and opinions
    seems like you got your wish, ideas and opinions, but some drifted way off the question you asked. i'll assume you're not intending to redesign the entire aircraft to incorporate all the esoteric solutions to perceived problems you didn't mention.

    i am familiar with the way kitfoxes are normally built. early models used bing blue fuel line, later models used mil-h-6000 "rubber" hose. i built and flew an avid flyer for over ten years. i installed bing blue fuel line throughout as per the kit contents and instructions. it is advertised as, and proved to be, compatible with autogas or avgas. the aircraft was hangared when not flown. there was no noticeable deterioration of the blue line in that ten years. it was still flexible and did not crack at the ends like rubber fuel line tends to do. in short, it did what it was supposed to do reliably over time. i see no problem with using it as the manufacturer recommends and as the kitfox assembly manual recommends.

    if you intend to use autogas but don't want to use bing blue tubing, i recommend avoiding mil-h-6000. i have seen it deteriorate within mere months of using premium autogas. it's not supposed to, but it did. i recommend automotive fuel line instead. NAPA's has proved compatible with autogas and avgas over the last 11 years in my applications.

    your mileage may vary.

  7. #17

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    Quote Originally Posted by rwanttaja View Post
    Remember, the P-51 had a fuel tank right behind the pilot...

    Ron Wanttaja
    at the risk of being misinterpreted because print doesn't convey a wink and a nod very well,

    remember that P-51 pilots were paid to take crazy risks.

  8. #18

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    Tygon fuel line from Graingers has lasted 15 years for me. With no sign of deteriortion.

  9. #19
    steveinindy's Avatar
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    I'll be wearing a helmet during the first 40 and beyond; looking doofy in the cockpit is better than looking good in a casket.
    Of course, there's a lot of folks who joke that helmets are there to allow a good appearance in the casket but I digress.....

    However, the location of the fuel tank is pretty much non-negotiable based on basic design and dimensions of the aircraft; installation and fuel line routing is going to be in the cockpit. That just means that a lot of attention to detail and foresight has to be put into them for safety.
    Then please, as your friend, I ask that you use a braid steel or similarly tough fuel line with a couple of quick disconnects to minimize the risk of spills. Placing the fuel tank as far back as the CG will allow is also a good idea.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  10. #20
    steveinindy's Avatar
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    Quote Originally Posted by cdrmuetzel@juno.com View Post
    remember that P-51 pilots were paid to take crazy risks.
    Kind of like HEMS pilots
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



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