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  #21  
Old 08-27-2018, 09:19 PM
Fred.Stucklen's Avatar
Fred.Stucklen Fred.Stucklen is offline
 
Join Date: Oct 2006
Location: Brooksville, FL
Posts: 320
Default Pump Gas

If "Pump Gas" can be used in autos, our aircraft systems can be designed to use it too.

I've been running 93 octane E10 in an IO-360 with 8.7:1 compression for the last 1000+ hours. My fuel system utilizes automotive fuel system design parameters to facilitate problem free operation. The fuel is pressure driven to the engine. The additional Aux pump will automatically be turned on (with an independent fuel pressure sensor and circuit) if the fuel pressure goes below a specific set point. All fuel hoses are either teflon or alum. All fuel system "O" rings have been changed to buttal rubber.
Testing with winter blended fuels on hot days and high altitudes has never shown any signs of vapor lock issues.
Use of "Pump Gas" in aircraft can be done, but the fuel system designs require the same solutions that the automotive industry implemented decades ago.


Quote:
Originally Posted by airguy View Post
I'm rolling up on 275 hours now on my IO360 running Walmart-grade 91 premium autogas with ethanol on 8.7:1 compression with no issues. I did build the entire fuel system on the airplane with ethanol exposure in mind and eliminated all but one natural rubber O-ring which I found a couple weeks ago, it finally started leaking at about 250 hours.

The engine is quite happy burning 91E10, in-flight performance is within a percent or two of the 100LL standard, I can't tell the difference without digging into the Dynon performance data on a long cross-country.

Handling the fuel here is going to be the trick for you and most others though. I am based on a private strip just over 30 miles from the nearest "real" airport with fuel - so I have my own tank on my strip. I took a used milk container, 125 gallons stainless, and steam cleaned it, set it on a 275-gallon chemical tote frame so I can pick it up with forks on a tractor, and put a pump and battery on the frame. I can fork it onto the back of my pickup and take it to town for a fill when needed, easy-peasy.
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RV-7A N924RV Flying (1520 Hrs & counting)
RV-6A N926RV 875 Hrs (Sold)
RV-6A N925RV 2008 Hrs (Sold)
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  #22  
Old 08-28-2018, 01:39 AM
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RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
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Default

Do not stress.

The PAFI process was fatally flawed right from the beginning. Recently proven.

There is a certification project almost complete and has taken time due funding and apathy of the market to get behind it, but is literally "months" or "weeks" from a major milestone.

G100UL is the likely fuel you will have when the time comes. So relax. Build on.
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  #23  
Old 08-28-2018, 02:54 AM
OkieDave OkieDave is offline
 
Join Date: Mar 2017
Location: Oklahoma
Posts: 102
Default

Quote:
Originally Posted by Freemasm View Post
Too low of a vapor pressure (related to the fluid property proper) will cause fuel to vaporize (vapor lock if in fuel line) and subsequent fuel starvation. This is realized when the local static pressure of the fluid is too low. This can happen when “drawing” fuel through a line e.g. engine fuel pump above low wing tanks. Mogas RVP isn’t held to as tight a tolerance as Avgas. In fact, MoGas tends to vary with seasonal blends/region where supplied. That is why an airframe must also be approved/STC’d for MoGas, not just the engine. High wing planes tend to be no issue as there is inherent head pressure. Low wing airframes tend to need full time duty boost pumps or a header tank to meet the requirements for the lower RVP. There’s plenty of smarter people than me in these forums that will tell me if i’m off. Maybe you’re telling me. Let me know. I’m always ready to learn more.
Quote:
Originally Posted by Fred.Stucklen View Post
If "Pump Gas" can be used in autos, our aircraft systems can be designed to use it too.
Can be, yes, but at what cost? Autos typically have the fuel pump inside the fuel tank, so there's no real "draw;" at worst, a couple of inches of rise, and a similar horizontal run. In an airplane, it can be several inches of rise (maybe as much as a foot, if you weren't careful with your design), and several feet of horizontal run, plus several bends.


Yes, you could use the automotive design of putting the pump in the tank, but now you're looking at multiple pumps, and you're also dealing with a tank that's shallower than the typical auto tank. Can it be done? Yes. Is it practical and cost-effective? Maybe, maybe not, and I lean toward "not."
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  #24  
Old 08-28-2018, 06:50 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
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Default

Quote:
Originally Posted by OkieDave View Post
Can be, yes, but at what cost? Autos typically have the fuel pump inside the fuel tank, so there's no real "draw;" at worst, a couple of inches of rise, and a similar horizontal run. In an airplane, it can be several inches of rise (maybe as much as a foot, if you weren't careful with your design), and several feet of horizontal run, plus several bends.


Yes, you could use the automotive design of putting the pump in the tank, but now you're looking at multiple pumps, and you're also dealing with a tank that's shallower than the typical auto tank. Can it be done? Yes. Is it practical and cost-effective? Maybe, maybe not, and I lean toward "not."
People have been flying low wing planes like RVs on mogas for years successfully. Follow a few simple rules and it works just fine. I've been doing it for 9 years now. No issues other than reducing the MAP limit down with my high compression turbo engine.

“A person who says it cannot be done should not interrupt the man doing it.”
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  #25  
Old 08-28-2018, 07:05 AM
Mudfly Mudfly is offline
 
Join Date: Dec 2011
Location: Alpharetta, Ga
Posts: 152
Default

Quote:
Originally Posted by RV10inOz View Post
Do not stress.

The PAFI process was fatally flawed right from the beginning. Recently proven.

There is a certification project almost complete and has taken time due funding and apathy of the market to get behind it, but is literally "months" or "weeks" from a major milestone.

G100UL is the likely fuel you will have when the time comes. So relax. Build on.
Thanks David. Somehow I have missed this G100UL fuel development project during my frantic internet research of the demise of 100LL. This sounds very interesting. I have taken a step back from the ledge. Lets hope they can keep the FAA satisfied and get the fuel refineries and suppliers to keep the cost reasonable.
This video is several years old, but has some good info for those not familiar with this G100UL fuel. For some reason I trust this guy and believe what he is saying.
https://www.youtube.com/watch?time_c...&v=vEcHW2B0vXE
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  #26  
Old 08-28-2018, 07:39 AM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,498
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I had absolutely no problems with vapor lock when I ran ethanol free 90 octane "recreational fuel" in my IO-540 RV-10, even on the hottest days here in Michigan. Rec Fuel is nothing more than ethanol free mogas some gas stations carry for our boats and other recreation vehicles. My engine was a Lycoming IO-540V4A5 with 8.5 pistons. I took some basic precautions during the build knowing I was going to run mogas by insulating the fuel lines FWF and shielding them from heat and a heat shroud with blast tube on the engine fuel pump. When I ran my plans to burn mogas by the engine guy from Lycoming during an Airventure Lycoming rebuild seminar that Lycoming put on he said "absolutely".
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  #27  
Old 08-28-2018, 08:41 AM
Freemasm Freemasm is offline
 
Join Date: Nov 2017
Location: Orlando
Posts: 60
Default Interesting comments

Forgive the small rant. The Spirit of Experimental/Homebuilt Aircraft is unique. It should challenge convention and often does. What is disheartening and dangerous are open ended statements asserting something is OK or correct without supporting facts. Because something was done once or even several times without consequence, doesn't make it technically sound. There are numerous statements in this thread that offer technical reasoning in support of one side of an argument while the other is essentially "been fine, so far." The Normalization of Deviation was central in the death of seven Astronauts and countless aviators. I've been closer to these situations than I ever could have imagined.

I probably need to take a break from reading these forums for a while. I can hear the "good riddance" going through many minds. If you want to call me the big hole, probably need to email or PM me. Build safe. Fly safe. Be careful what you post here. I've learned a lot from you guys.

Scott F
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  #28  
Old 08-28-2018, 08:45 AM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
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Quote:
Originally Posted by OkieDave View Post
Can be, yes, but at what cost? Autos typically have the fuel pump inside the fuel tank, so there's no real "draw;" at worst, a couple of inches of rise, and a similar horizontal run. In an airplane, it can be several inches of rise (maybe as much as a foot, if you weren't careful with your design), and several feet of horizontal run, plus several bends.


Yes, you could use the automotive design of putting the pump in the tank, but now you're looking at multiple pumps, and you're also dealing with a tank that's shallower than the typical auto tank. Can it be done? Yes. Is it practical and cost-effective? Maybe, maybe not, and I lean toward "not."
The trick here, as you noted, is to reduce the pressure drop in the draw to the suction of the pump as much as possible. I eliminated the engine-driven pump and installed two electric pumps on the floor in the cockpit in the standard boost pump location, so the pumps are already as low as the bottom of the fuel tank. I used stainless-braided Teflon core hoses from Tom Swearingen for my fuel lines in from the tank to my Andair duplex fuel valve to eliminate tight bends and 90's to reduce the pressure drop, and I put 85-micron filtration in each line just prior to the pump, with one single 35-micron filter downstream of the pump. Once the fuel gets TO the pump, then it's pressurized and everything becomes automotive-standard from there.

By virtue of removing the engine-driven fuel pump, I'm automatically at a single-point-of-failure on the pump system if I don't have multiple pumps - I just installed an SDS dual pump module that has a pair of them in parallel, so a backup pump is plumbed in just waiting for the switch to flip. Total cost for this? I dunno, didn't track it very closely honestly, but certainly less than $1500 including the lines and insulation. I'm saving easily $1 per gallon with a conservative average fuel flow of 8 gph and I've been doing it for about 275 hours now - so it's already well paid for itself.
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Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.

Last edited by airguy : 08-28-2018 at 08:47 AM.
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  #29  
Old 08-28-2018, 08:58 AM
airguy's Avatar
airguy airguy is offline
 
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Location: Garden City, Tx
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Quote:
Originally Posted by Freemasm View Post
I probably need to take a break from reading these forums for a while. I can hear the "good riddance" going through many minds. If you want to call me the big hole, probably need to email or PM me. Build safe. Fly safe. Be careful what you post here. I've learned a lot from you guys.

Scott F
Don't leave on our account - there is always value in discussion and even occasional dissention, as long as it's kept in the realm of civil discourse. Your first post on this thread came across as "You can't do that" and that automatically will start a (sometimes heated) discussion amongst the experimental community - especially when people are already quite obviously doing it and have been for some time.

As you know, there are blanket rules designed to keep the tourists from falling into the volcano and there's nothing wrong with that - but occasionally you get people with enough knowledge and experience that they can duck under the rope and walk right up to the edge of volcano safely. It happens everyday - just not in large quantities and not always in public view - but it does happen.
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Greg Niehues - VAF 2018 dues paid
Garden City, TX
N16GN flying! http://websites.expercraft.com/airguy/
Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
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  #30  
Old 08-28-2018, 09:47 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,097
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There is a difference between blindly dumping a load of auto gas into an airplane and "seeing what happens" and designing the system to use it. As others have done, my system has zero 90 degree fittings (to include changing the standard Van's in tank pickup), the fuel pump is mounted at BL 0 against the spar (as low as possible without punching out the bottom of the OML), and is chemically resilient for modern Mogas. While this does not guarantee success, it's stacking the deck as much in my favor as possible. A detailed flight test series will show if it's enough.

This forum has long fought the battle between presenting technical information to consenting adults vs. "protecting the children"... It's the latter that prompted the warning statement on my signature line.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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