Testing a fuel for presence of vodka.

C. Beaty

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Why don’t modern automobiles suffer from vapor lock?

It’s because modern automobile designers aren’t so dumb as to operate the fuel system with a suction head. There is always a fuel pump at the bottom of the fuel tank.
 

Vance

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Why don’t modern automobiles suffer from vapor lock?

It’s because modern automobile designers aren’t so dumb as to operate the fuel system with a suction head. There is always a fuel pump at the bottom of the fuel tank.
The Cavalon has its fuel pump below the fuel tank.

In my opinion on a fuel injected Lycoming the problem of vapor lock comes from the fuel lines from the fuel divider to the injectors after the fuel pump and throttle body.
 

Vance

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Five engine outs in flight running the same Rotax 914 engines on three of the same type of aircraft in just a few short years is not a fuel type problem.

To wit, I am unable to find a single instance of a running Yamaha engine quitting due to vapor lock, whether on one of the countless thousands of sleds or some 200 aircraft, since they were introduced 17 years ago. These engines have been run for all of these years under all kinds of extremes and conditions at altitudes up to 10,000 ft MSL, in the air and on the ground.

Vapor lock shutting down a running engine is a serious design flaw - be that the of engine or the guy who routed the fuel lines, or a combination of both.

Seems to me someone needs to work this problem out before they kill themselves, and maybe a passenger.

Simply running 100LL is no acceptable solution for so-called vapor lock.
It is not the 914 engine; in my opinion it is the circumstances of the fuel formulation and the installation.
 

WaspAir

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Vapor lock shutting down a running engine is a serious design flaw - be that the of engine or the guy who routed the fuel lines, or a combination of both.

Seems to me someone needs to work this problem out before they kill themselves, and maybe a passenger.

Simply running 100LL is no acceptable solution for so-called vapor lock.
I'm glad your Yamahas have been immune, but not everything is, and in-flight stoppages can happen. In my post #8 above I pointed out that:
the Piper Apache and Comanche-250, and Cessna Skyhawk with Avcon’s 180HP conversion all failed testing, and cannot legally run autogas.
They are fully standard-airworthiness certified running on 100 LL, so at least the FAA considers that an acceptable solution.

The instructions that came with my STC and Hodges tester suggest blending with avgas until the mixtures passes, and FAA blessed that STC.
 
Last edited:

JEFF TIPTON

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Vapor lock can occur from many cases.

The Piper Navaho has a boost pump that runs continuously. By applying pressure to the fuel line, vapor lock on that aircraft is controled.

The 180 horsepower Cessna 172 problems come the fuel systems designed to provide fuel flow for the 150 - 160 horsepower engine. It has just enough resistance in fuel flow to allow vapor lock in some conditions.

Some installations were certified with just the addition of insulation on the fuel line or rerouting the fuel line to move it away from the exhaust or to an area that allows cooling air to reduce the fuel temperature.
 

First pilot

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For those who want to rid alcohol from gas and wish to go to ther trouble: A container with a sump and drain makes it easy. For 10% Ethanol, add 10% water also. The Ethanol is absorbed in water. So draining the water drains the Ethanol also. Octane is not absorbed in water or Ethanol.
 

Tyger

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"In terms of its octane rating, ethanol has a rating of 113. As mentioned above, fuels with a higher octane rating reduce engine knocking and perform better. Also, almost all gasoline in the US contains 10 percent ethanol. When you mix 10 percent 113 octane ethanol with 85 octane gasoline it increases the octane two points to the normal 87 octane most consumers use. So the higher the ethanol content, the higher the octane. The octane rating for E15 (15% ethanol) is 88 octane and E85 (85% ethanol) is 108 octane."

 

NoWingsAttached

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Having had five engine outs from vapor lock in three different 914 powered Cavalons I can attest to the reality that vapor lock using auto fuel without alcohol can be problematic. Four were over 5,000 feet density altitude; one was at less than 1,000 feet density altitude.

Once 100LL was introduced the problem evaporated.
Surrounded by fidiots who act like they know it all when in fact they are...fidiots. "I CAN ATTEST TO THE REALITY THAT VAPOR LOCK USING AUTO FUEL WITHOUT ALCOHOL CAN BE PROBLEMATIC [because I] HAD FIVE ENGINE OUTS FROM VAPOR LOCK."

Vance also posted elsewhere on RF that "Weight and thrust have nothing to do with aircraft performance".

He also decreed on my accident thread from 2016 that the tides at Tybee Island are 4'. But our one, true God didn't listen and the tides are, and always have been 8-9 ft off Tybee. Back to topic.

Gee, with so many OTHER people reporting carb-related problems with Rotax 912 and 914 engines, could it POSSIBLY be something else? Oh, no. Not if our very own god and king, his majesty Vance Breeze has anything to say on the matter. And trust me when I say Vance Breeze has something to say on every matter, and that he is an absolute end-all authority on everything, including accidents discussed on RF (e.g. Chris lord, Greg Mills, etc.).

Five engine outs on three engines, all 914. Yeah, let's blame the fuel, Vance. Duh.

Adding a metal to a liquid does not change its vapor pressure (volatility). Changing the percentages of all of the various chemical liquids found in gasolines does. Don't believe me? I don't blame you. I'm such an asshole, and I only have a puny BS in Chemistry from U of M. So please, instead, just ask my wife. She's a research PhD @ USC Chem (Piled Higher and Deeper). I did. She agrees that I am an asshole, Vance is a complete idiot, and lead does not affect volatility in gasoline. Hat trick.

But Vance is the authority here, on RF, right? He figures if he posts enough that eventually people will understand that he is the foremost leading authority on anything and everything on RF, bar none. At least in Vance's little pretend world with his prancing little Puff and its sissy sisters with all of their 5 engine outs, and that flying brick we've all come to affectionately know as the "Predaturd". I digress. Back to gasoline and what causes vapor lock.

Butane. Reducing butane % in gasoline changes Reid Vapor Pressure (RVP, an industry standard VP taken at 37.8° C) a lot.

Lead has nothing to do with volatility, and does nothing to affect vapor lock.

Pure ethanol actually has a RVP of just 18 kPA at 40° C, believe it or nuts. Click here: 200 Proof Ethanol Vapor Pressure,

Exxon's Avgas, with a 1.06% maximum TEL (lead) content, and it's 100LL with a max content of 1/2 that, only .53%, both have the same RVP (look it up) of 49kPa. That's 7.1 PSI for the freshman entering this semester.

Now what is pump gas RVP? Depends on what state, locality & time of year we are talking about.

During summer months in many places the federal mandate is 7- 7.2 PSI.

Wait, what is that you say again? 10% Ethanol gasoline has a RVP that is the same as not just 100LL, but the really good stuff - AVGAS!?!?!?

Yes, grasshopper. Vance is full of :poop:. Always has been. Always will be. And no amount of postings - not even when he gets to King of the RF Hill with 17,000 in the next week or two (joke) - can change that.

And whatever happened Char? Is that short for Charlene? What was her last name at the time she went missing? Did she chantge it back to her maiden name or was it still Breeze? Where did she go missing from? Is she still missing today? So many questions, so little time.
 

WaspAir

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Okay, we all know by now that you hate Vance. But you don't have to repeat that in offensive terms in every post on every thread. I would be interested in your technical arguments and experience if I didn't have to wade through all that ugly personal screed to find the aviation substance you've blended in with it. As it is, your bitterness and insults make it look like there really is a person with a problem here, but the initials are not VB. Please, drop the venom and just tell us what you can about gyroplanes. Polluting your posts with hate doesn't make your technical statements more persuasive. - - quite the opposite!

This is a long and (hopefully) gentle way to say, "GIVE IT A REST ".
 

Vance

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Surrounded by fidiots who act like they know it all when in fact they are...fidiots. "I CAN ATTEST TO THE REALITY THAT VAPOR LOCK USING AUTO FUEL WITHOUT ALCOHOL CAN BE PROBLEMATIC [because I] HAD FIVE ENGINE OUTS FROM VAPOR LOCK."

Vance also posted elsewhere on RF that "Weight and thrust have nothing to do with aircraft performance".

He also decreed on my accident thread from 2016 that the tides at Tybee Island are 4'. But our one, true God didn't listen and the tides are, and always have been 8-9 ft off Tybee. Back to topic.

Gee, with so many OTHER people reporting carb-related problems with Rotax 912 and 914 engines, could it POSSIBLY be something else? Oh, no. Not if our very own god and king, his majesty Vance Breeze has anything to say on the matter. And trust me when I say Vance Breeze has something to say on every matter, and that he is an absolute end-all authority on everything, including accidents discussed on RF (e.g. Chris lord, Greg Mills, etc.).

Five engine outs on three engines, all 914. Yeah, let's blame the fuel, Vance. Duh.

Adding a metal to a liquid does not change its vapor pressure (volatility). Changing the percentages of all of the various chemical liquids found in gasolines does. Don't believe me? I don't blame you. I'm such an asshole, and I only have a puny BS in Chemistry from U of M. So please, instead, just ask my wife. She's a research PhD @ USC Chem (Piled Higher and Deeper). I did. She agrees that I am an asshole, Vance is a complete idiot, and lead does not affect volatility in gasoline. Hat trick.

But Vance is the authority here, on RF, right? He figures if he posts enough that eventually people will understand that he is the foremost leading authority on anything and everything on RF, bar none. At least in Vance's little pretend world with his prancing little Puff and its sissy sisters with all of their 5 engine outs, and that flying brick we've all come to affectionately know as the "Predaturd". I digress. Back to gasoline and what causes vapor lock.

Butane. Reducing butane % in gasoline changes Reid Vapor Pressure (RVP, an industry standard VP taken at 37.8° C) a lot.

Lead has nothing to do with volatility, and does nothing to affect vapor lock.

Pure ethanol actually has a RVP of just 18 kPA at 40° C, believe it or nuts. Click here: 200 Proof Ethanol Vapor Pressure,

Exxon's Avgas, with a 1.06% maximum TEL (lead) content, and it's 100LL with a max content of 1/2 that, only .53%, both have the same RVP (look it up) of 49kPa. That's 7.1 PSI for the freshman entering this semester.

Now what is pump gas RVP? Depends on what state, locality & time of year we are talking about.

During summer months in many places the federal mandate is 7- 7.2 PSI.

Wait, what is that you say again? 10% Ethanol gasoline has a RVP that is the same as not just 100LL, but the really good stuff - AVGAS!?!?!?

Yes, grasshopper. Vance is full of :poop:. Always has been. Always will be. And no amount of postings - not even when he gets to King of the RF Hill with 17,000 in the next week or two (joke) - can change that.

And whatever happened Char? Is that short for Charlene? What was her last name at the time she went missing? Did she chantge it back to her maiden name or was it still Breeze? Where did she go missing from? Is she still missing today? So many questions, so little time.
Having had five engine outs from vapor lock in three different 914 powered Cavalons I can attest to the reality that vapor lock using auto fuel without alcohol can be problematic. Four were over 5,000 feet density altitude; one was at less than 1,000 feet density altitude.

Once 100LL was introduced the problem evaporated.
This thread is about testing for alcohol in MOGAS.

Alcohol is not the only problem with MOGAS and if felt there was value in sharing my no alcohol vapor lock experiences.

You don’t have to look far to find stories of problems with MOGAS in aviation.
If you want to read the whole article: https://iopscience.iop.org/article/10.1088/1757-899X/370/1/012008/pdf

Conclusion Mogas normally has a much higher vapour pressure, which varies seasonally. With a high Reid Vapour Pressure (RVP) fuel the risk of vapour lock during take-off and climb increases, particularly if the aircraft had been parked in high ambient temperatures and does not have a gravity-fed fuel system. The higher volatilities and vapour pressures of motor gasoline (MOGAS) may overtax the vapour handling capabilities of some airframe and engine fuel systems leading to vapour lock and carburettor icing. The higher volatilities also increase the risk of fire hazard. While the tendency of avgas to vapor lock increases with volatility, fuel overheating is the main cause of vapor lock. Local temperatures in the fuelsystem are determined by how hard the engine is working and how well the fuel system is isolated from the heat of the engine. Fuel residence time in the hot sections of the system, mechanical vibration, and other factors also play a significant role in vapor lock behavior. The altitude at which the engine is operating has two opposing influences: ambient temperatures are lower at higher altitudes, which should improve fuel system cooling; but ambient pressures are also lower, making vaporization easier. The design of an aircraft fuel system must take all the above factors into account to ensure that liquid fuel, with little or no free vapor, is delivered to the engine’s fuel metering system.

Aerospace and Mechanical Engineering (AeroMech17) IOP Publishing IOP Conf. Series: Materials Science and Engineering 370 (2018) 012008 doi:10.1088/1757-899X/370/1/012008
 
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