Can it be September already?  Delta Variant.  Kabul.  Zero-emissions.  Unleaded AvGas.  SAF.  Lots going on in the world and Baere is trying to wend its way through it all the same as most of you.  Our president is scheduled to attend the US DoD's Turbine Engine Technology Symposium in Ohio this month and to be honest we all are a little skittish about it.  We are vaccinated, but the conflicting reports from the mainstream media makes it difficult to know if we are being cautious or stupid to leave the office.  Indiana's numbers are up as is most of the country, so it does not seem to make a lot of difference whether we stay here or go out.  So we are going to go with being cautious.

What about zero-emissions?  I posted last time about "SAF" both "Synthetic Aviation Fuel" which is technical, and "Sustainable Aviation Fuel" which is policy.  It is clear that the policy makes sustainable aviation fuel a major component in reaching zero-emissions, but what about Hydrogen Powered or Electric Airplanes.  You may be saying that as an aviation fuels and lubricants consulting company, we might be dreading electric airplanes.  The truth is, no we aren't.  While we would not have a traditional liquid fuel involved, we are finding that the lubrication of these new concepts is coming with a whole new set of challenges which will keep Baere's chemists busy for a while.  Furthermore, there are the different ways to an electric airplane.  For example, fuel cells.  For large aircraft, at least in the near term, it is not going to be practical to have on-board batteries to run the motors.  One reason is power density.  To have enough capacity with contemporary battery technology, means a great deal of battery weight.  The downside is that batteries weigh the same whether they are charged or depleted.  So you end up with a negative logarithmic sort of thing where the depleting batteries are having to expend their remaining capacity to just move the weight of the dead batteries.  That makes on-board fuel cells an attractive option.  Instead of charging the batteries and bringing them with, make the power as you need it.  This means an on-board fuel.  What sort of fuel?  Well, we know that you can use contemporary jet fuel for this, that is one option.  Another that is attractive environmentally is a hydrogen fuel cell.  This comes with a new slate of engineering challenges, one of which is very firmly in the chemist's bailiwick - storing and moving liquid or gaseous hydrogen.  So that means, our chemists are busily studying and learning, and being right in the thick of the technical aspects.

I have also noticed an increase in discussions about unleaded aviation gasoline.  Some of the articles have been a bit fatalistic about the entire process.  And I can see why.  From the outside it looks like there has been a lot of money spent and a lot of tests run without making any progress.  Let me just say that had it been easy, it would have been done in the 1980s when there was the last big push to eliminate lead.  The fact of the matter is, lead is very good at what it does which is, at least partly, to control how the flame front moves across a potentially very large piston head.  "We did it for cars a long time ago!  Didn't we learn anything useful for airplanes?"  One of the largest challenges, pardon the pun, is that the piston in your car is actually pretty small.  The distance the flame front moves as the fuel is combusted is actually relatively short.  In some aircraft engines, the diameter of a piston is as high as 8 or 10 inches.  Keeping the flame front moving smoothly and in a controlled way across 10 inches is a bigger challenge than across 4 inches.  Finding something that can do what lead does, that also isn't just as or more toxic than lead, is a trick.  If it weren't for the big piston engines that need a lot of power, we might not need the high octane aviation gasoline and we might be done by now.  But the fact is, we do.  And no one, including the FAA and the EPA wants to just tell everyone with a really big engine, "Sorry, you are grounded."  That means, a lot of very smart people are working very hard to find a way to safely fuel all the aircraft in the fleet without having to replace every hose, seal, piston ring, and carburetor.  Will we be successful?  Only time will tell.  But suffice it to say, it is not the chaotic mishmash of unguided effort some reports suggest.

Aircraft Design