Unleaded Avgas Update

[lr172]

Originally Posted by theduff

If you can mix it with 100LL wouldn’t that mean the density is the same ? If you look at the picture at the on AVWeb ( link post 39 ) with both fuels mixed there is no stratification. With 100LL Blue and G100 UL yellow you get a beautiful green !
Am I being over simplistic to think that means the densities are equal unlike the oil and water mix we’ve all seen.

Yes, you are over simplifying.

Not a chemist, but I don't believe that density has anything to do with solubility, though the densities will dictate the stacking of layers of stratification in insoluble mixtures, like oil and water. Thought is was about molecular bonding; Think back to HS science - some molecules happily combine with others and some don't. Something about free neutrons at the atomic level, I think. Mix oil and gasoline and they combine perfectly eventhough they are very different densities, but very similar at the molecular level. Gasoline starts as oil and requires heat and evapoation to refine it out. It doesn't naturally create different layers. Oil is around 7.5 lbs/gall and gas is around 6 lbs/gallon. Salt water doesn't perfectly mix with fresh water due to being the same density; We know they are different densities, as we humans float on salt water and sink in fresh water. Salt and water are also different densities, but mix perfectly and don't separate, otherwise the oceans would be freshwater with a layer of salt at the bottom.

Larry

[KayS]

Seems that G100UL has basically the same density as regular car gas or the mogas many of us use.

[BillL]

Originally Posted by lr172

Yes, you are over simplifying.

Not a chemist, but I don't believe that density has anything to do with solubility, though the densities will dictate the stacking of layers of stratification in insoluble mixtures, like oil and water. Thought is was about molecular bonding; Think back to HS science - some molecules happily combine with others and some don't. Something about free neutrons at the atomic level, I think. Mix oil and gasoline and they combine perfectly eventhough they are very different densities, but very similar at the molecular level. Gasoline starts as oil and requires heat and evapoation to refine it out. It doesn't naturally create different layers. Oil is around 7.5 lbs/gall and gas is around 6 lbs/gallon. Salt water doesn't perfectly mix with fresh water due to being the same density; We know they are different densities, as we humans float on salt water and sink in fresh water. Salt and water are also different densities, but mix perfectly and don't separate, otherwise the oceans would be freshwater with a layer of salt at the bottom.

Larry

Have you seen the brine pools at the bottom of the Gulf of Mexico?

Try alcohol and water - vodka - -two different densities, but completely miscible - that would describe compatibility of the two fuels.

[lr172]

Originally Posted by BillL

Have you seen the brine pools at the bottom of the Gulf of Mexico?

Try alcohol and water - vodka - -two different densities, but completely miscible - that would describe compatibility of the two fuels.

according to the referenced link, that is salt tectonics due to large quantities of salt trapped under sediment and doesn't really prove that salt will not naturally separate from water. It only proves that different concentrations of salt water can exist in a common body of water. That is a pretty unique penomenon, though I get your point.

Larry

[erich weaver]

Wow, talk about thread drift....

[pjc]

Originally Posted by lr172

Yes, you are over simplifying.

Not a chemist, but I don't believe that density has anything to do with solubility, though the densities will dictate the stacking of layers of stratification in insoluble mixtures, like oil and water. Thought is was about molecular bonding; Think back to HS science - some molecules happily combine with others and some don't. Something about free neutrons at the atomic level, I think. Mix oil and gasoline and they combine perfectly eventhough they are very different densities, but very similar at the molecular level. Gasoline starts as oil and requires heat and evapoation to refine it out. It doesn't naturally create different layers. Oil is around 7.5 lbs/gall and gas is around 6 lbs/gallon. Salt water doesn't perfectly mix with fresh water due to being the same density; We know they are different densities, as we humans float on salt water and sink in fresh water. Salt and water are also different densities, but mix perfectly and don't separate, otherwise the oceans would be freshwater with a layer of salt at the bottom.

Larry

OK, I am a chemist, and have no problem with the gist of your post. However, solubility has nothing to do with free neutrons, thank god. Free neutrons are unstable and give rise to beta emissions (a form of radioactivity).


Now back to your regularly scheduled programming ...



Peter

[VA Maule]

newt and RV6 flyer:
I fully understand that we can run our experimental engines on moonshine laced with goat’s milk if we could get it to burn and not spoil in the unrefrigerated wing tanks

My comment was more intended for the GA fleet as a whole that our RV’s are a subset of. I suspect that a large percentage of us currently fly certified planes as well.

[RV6_flyer]

Originally Posted by VA Maule

newt and RV6 flyer:
I fully understand that we can run our experimental engines on moonshine laced with goat’s milk if we could get it to burn and not spoil in the unrefrigerated wing tanks

My comment was more intended for the GA fleet as a whole that our RV’s are a subset of. I suspect that a large percentage of us currently fly certified planes as well.

It depends on the FAA. (and maybe the insurance underwriters plus manufacturers)

An example is that they (FAA) want to promote safety and up until recently it was acceptable to get flight training in an experimental airplane. Due to an experimental warbird taking advantage of that, the FAA went to court and won their case by throwing all training in experimental aircraft out the window. Now we require a LODA to get flight training in our experimental aircraft.

The FAA decided to go down one path for unleaded avgas and it may not be the smoothest path. We as the end user of "certificated" aircraft may have a few extra hoops to jump through.

[12vaitor]

Should be interesting to see how the self-service pumps handle G100UL. I did hear one comment that current UL self-serve pumps somehow check your tail number with an STC list and will not turn on if the AC is not on the list. I presume this is a SWIFT 94UL pump because you need their STC to use their fuel. While experimental AC do not need an STC, the distribution infrastructure may require you to buy one anyway. I am sure we will see a lawsuit from a crash that involves an FBO fueling a plane with G100UL that did not have an STC for it.

George mentioned the STC cost will be based on engine HP. I hope the FAA will eventually approve/declare G100UL as a 100LL equivalent with no STC required, otherwise you may end up needing multiple fuel STCs (MOGAS, SWIFT, GAMI, whoever is next) depending on where you stop for fuel.

John Salak
RV-12 N896HS

[RhinoDrvr]

Surely STC compliance would fall on the PIC and not the fuel supplier? Sort of like operating an airplane at an STC placarded increased gross weight without the STC?