Airborne_Again wrote:
AFAIK there are STCs that improve e.g. STOL performance that do not provide revised performance figures for the POH. As performance improves the original figures will be conservative.
What kind of logic is that ? That is some bending of the meaning of the word conservative as used in engineering. The word conservative does not equal lazy engineering. If a change on the aircraft, like that STC to improve STOL performance, then this should be noted in the performance figures, because that’s the whole point of the STC. The only logical meaning of the above is that the STC does not degrade any of the original performance figures as stated in the POH. The main improvement is not something that’s even mentioned in the original POH.
Vortex generator on the wing is a typical STOL enhancing modification. It will effectively decrease stall speed. However, this is not the usual reason to install them. The main reason is to change the stall characteristic of the wing. For a STOL aircraft, in STOL use, a problem is the wing will lose it’s lift too abruptly to be fully controllable by the pilot. The problem with that is the aircraft will stop flying and fall down when doing a STOL flaring. It’s hard for the landing gear, and hard on the piece of mind 
It also doesn’t look good Vortex generators will soften that transition from flying to stalling over a wide range of degrees. The decrease in stall speed is nice, but largely irrelevant (unless doing STOL competitions). What is relevant is to have full control at very high angle of attack without the aircraft suddenly and abruptly falling out of the sky. Surely this will also shorten landing and take off distance, change Vx and so on, but it will not degrade any performance numbers other than a possibly measurable difference in top speed (largely irrelevant).
Besides, in a STOL aircraft, no one cares what the actual stall speed is. You don’t fly by the numbers.
Peter wrote:
But maybe not if the fuel burn is lower?
AFAIK there are STCs that improve e.g. STOL performance that do not provide revised performance figures for the POH. As performance improves the original figures will be conservative.
because patents are useful for impressing customers, putting off casual rip-off artists, lubricating VC (vulture capital) funding or acquisition
That’s all true, but in my experience, large tech companies write patents for a different reason: to have a big patent portfolio. That way when another company threatens them with a patent, they just say, “look, we’ve got a zillion patents, and you’re bound to be infringing some of them, so let’s just have a mutual global licensing pact”.
My former employer is an example. They strongly encourage engineers to come up with patents, and will go forward with anything that makes any kind of sense including a reward for the employee as well as the considerable cost of obtaining the patent. But afaik they have only ever tried to enforce a patent once, and that was to try and slow down a very successful competitor for whom they had a visceral personal dislike. And in the end… there was a settlement and a mutual licensing deal.
Hmmm – a very good point 
But maybe not if the fuel burn is lower? If it was higher then you would deffo need a new AFMS for the fuel. That doesn’t actually need an STC AFAIK but the approval process for any AFMS is complex; I did it for the SN3500 about 10 years ago, and I had the help of a senior FAA inspector.
As fuel burn is lower with 100UL, aren’t all POH numbers to be updated ? Doesn’t it require an STC?
Airborne_Again wrote:
But then GAMI could just hand out the STCs free of charge. That would certainly help demand…
Yes, and it’s total bollock not to do so. No one will request that STC as long as the fuel is not available. The costs for the STC should be regarded as a PR coup. Like an advertiser.
Anyway: if they fail, the STC gets worthless. So holding back the STC just doesn’t pay out.
From that AVWEB video earlier, the “secret ingredient” is manufactured at one single place on the globe: Europe somewhere. It’s used in some paint, but it’s also something they don’t want to use. Which is why it’s produced only at one refinery now. It’s a product close to end of life, much like TEL.
I just cannot see this G100UL going anywhere in practice. A larger and larger part of the GA fleet is non certified. With this MOSAIC thing in the US, this will take another big bite. No Rotax engine of any kind will ever have any benefit from this fuel, and Rotax slowly but surely increases in HP (915/916) in the process of conquering the world. The non certified fleet will go with whatever is cheapest and will turn the propeller without breaking anything in the process. If an STC is needed, then this fuel will never be the one fuel to serve all in any case. Those pushing this fuel are either brain dead or in bed with GAMI by the looks of it.
As of today 100LL is no problem for anyone except a handful of pilots and GAMI. Neither the FAA or EASA is doing or pushing anything. There are no environmental organizations doing anything. The debate is dead. It’s all about alternatives to fossil fuels today. Stirring up the environmental debate will only result in one thing: the GA fleet will have to use a fuel with a certain amount of synthetic or bio-fuel added.
IMO this G100UL is more of a additional reason to head towards Jet A1 than it is a solution to a real problem.
Silvaire wrote:
Other than it being a way for GAMI to make money up front, the reason for STC approval is that otherwise aviation fuel has to be ASTM approved.
But then GAMI could just hand out the STCs free of charge. That would certainly help demand…
Enforcement will be zero, IMHO. It’s totally unworkable.
Which BTW means that unless there is an applicable GAMI G100UL STC for your type of plane in your country of registration, I don’t believe your plane can legally use G100UL, if it ever does become commercially available. The game with STCs is not unlike Garmin’s game in using STCs to force you to pay their dealer for installation. All this stuff is nonsense IMHO, private companies using a combination of government regulations to manipulate people into sending money to the company if they want to use their own property, whether it be gasoline or avionics. Best to stay uninvolved IMHO.
