Getting the Lead Out

[hharney]

https://www.avweb.com/eletter/archiv...t=email#231381


Scroll down and find the layman's version of the current issues with the unleaded fuel replacement program. Sounds like things got a little sticky at the presentations in Oshkosh. Now the FAA says they are out of money and the original two companies that had been selected have to let more participants into the private party. What a mess.........

[n86121]

All combustion engines suck in fuel and air, misting the fuel to get the right ratio, light it off with a spark then blow the expanded hot gasses out the exhaust.

Everything else is merely a refinement of that formula.

My son has a highly modified race car. Oversize the turbo. Put a fat 3 in exhaust so it can breathe easier. Some larger injectors, and fuel pump. Reprogram the ECU on a dyno, and all is well. 350 HP out of basically a 120 hp engine.

So it would seem to avoid detonation, one could change the timing on our farm-tractor aircraft engines to accommodate lower octane fuel. While they may not put out exactly the same HP as before, no detonation issues.

Maybe you only get 180HP out of a 210 hp engine?
Maybe you can't go to 30k anymore.

So you de-rate the whole aircraft performance to what the engines CAN put out.
Better than writing off the whole asset.

The experimental guys basically have to do it.
While their engine performance is known,
the capabilities of the aircraft have to be found out empirically
given whatever engine is on it.

So like that, just go the other way.

Yeah, yeah, I know, FAA would never allow that. Blah blah blah..

BUT, subtract the bureaucratic impediments, and the physics seem undeniable.

An aircraft declared experimental is not bound.

What am I missing?

[JimC]

Originally Posted by n86121

What am I missing?

You didn't miss anything on the physics side. It's sound logic. It's the FAA that'll getcha (surprise!)

"An aircraft declared experimental is not bound." This is correct, but it is very difficult (bordering on impossible) to convert a certified aircraft to a usable experiential. Yes, you can move it to experimental R&D, but your operating limitations will be extremely restrictive. You can't get to experimental A-B without redesigning and rebuilding 51% of the aircraft. That's where all the homebuilts are.

[YankeeClipper]

Wouldn't it be better to hold out until they develop something that maintains current power, safely? I'm not sure I'd be shopping for a plane through this forum any more if I thought there were alternatives that didn't need de-rating.

Also, my reading suggests there are other considerations beyond detonation being addressed, such as erosion of parts that hold up fine in 100LL (not because of the lead itself). Non-linearities in combinations is another, as mentioned in the AVWeb write-up.

[n86121]

I was at an aeronautics conference in the midwest some years back.

One fellow told how he 87 year old dad wanted to fly his tail dragger to the event, (we are talking open plains), but his medical had lapsed.

The son said, quite correctly, "Dad, what are they going to do to you?"

----

The only real constraints, other than the laws of physics, are those we follow voluntarily. Like most laws or regulations, they only apply to anyone paying attention.

The issue would be limited availability of insurance.

But then, my gosh, there are places and people who don't carry any...

--

Yes, the FAA has a path to 'certify' an aircraft 'experimental,' but only for a limited time, subject to renewal.

My own 337 had some ...ah, er, um 'modifications' (for the USGOV), and the paperwork makes interesting reading.

If my choice was to fly a 'something like' 190HP 337,
because there was no path for the FAA to act (willing or otherwise),
or write it off and park the airplane in the trees, ....

Somewhere in ....somewhere, I read somewhere, is a single Russian helicopter that someone stuffed a V8 agricultural engine into it. It actually flies....last I read.

So physics FIRST. Then other considerations come into play.

[hharney]

It's just all politics guys, we know that even the 100LL issues is really not an issue. I agree the new fuel needs to get us from point A to point B but all this bureaucratic cramp that has to be met is just a bunch of paper pushing. I think that the engine manufacturers should be more involved than they are but they probably just want to sell more engines. We are driving 50 year old airplanes with 100 year old engine technology. And 99% of that reason is because the certification process is so expensive and complicated. We have created a mountain out of a mole hill. I ain't going to get any better so enjoy it while we can before we all park our birds in front of our houses as monuments

[hharney]

https://www.avweb.com/avwebflash/new...-231453-1.html