Looking To The Future…

About the fuel issue:

As You all know there has been a lot of different fuel qualities but today the most commonly used is AVGAS 100LL which has its origins in the AVGAS 100/130.

One difference is that AVGAS 100LL has a considerably lower contents of T.E.L. which was brought on by environmental considerations.

Less T.E.L. doesn´t equal reduced performance though, a comparision below according to U.S. specs:

73 and 80 octane = no T.E.L.
80/87 grade = 0.5cc
91/96 grade = 4.6cc
100/130 grade = 4.6cc
108/135 grade = 3.0cc
115/145 grade = 4.6cc

108/135 grade is the demonstrator of my point.

If I recall correctly, the contents of T.E.L. in AVGAS 100LL is 2.0cc.

To add to the confusion there was a change in the convention of designations:

AVGAS 100/130 gives two values, one for weak mixture (100) and one for rich mixture (130). The new convention is to only designate the fuel by its weak mixture grade.
The AVGAS 100LL actually has a rich mixture grade of 130!

The problems with the lower T.E.L. contents was in other respects, valves sticking and increased valve seat wear. It seems like this was a problem when 100LL was introduced and changes to lubricants and engines have provided the cure.

I don´t know about other countries but in sweden AVGAS 91/96UL is available, UL = Un Leaded.
Most General Aviation engines can be run on this fuel, the main exceptions being those with fuel injection.

I believe that there are two considerations:

1) The octane rating.

If a boost of +18psi can be used on 100/130 a reduction to somewhere between +6psi and +12psi might be the result in this respect if using 91/96.

2) Is the T.E.L. essential in other respects?

I´ve mentioned the valve problems but if different materials and/or valve clearance in the bushings are used it might work.

(I´m speculating a bit here!)

A few interesting? links:

http://www.shell.ca/code/products/aviation/products/fuels.html

http://www.aopa.org/whatsnew/regulatory/regunlead.html

Regards,
Christer

Edited: I found this link too:

http://autofuelstc.com/pa/LeadD-4814.html

It may be allright in the US for now, but just imagine another “green” wave at EU-level prohibiting all leaded fuels? Then GA will be grounded whether they like it or not. I also believe that this trend will sooner or later arrive in the US and it is my opinion that it is very dangerous ignorance not to start getting very serious about developing a replacement fuel.

Kenneth

You are quite right about the question of fuel. The Shuttleworth Collection have had a major problem as many of their aircraft can’t even use neat 100LL, they need 85 octane. For a long time they were running short of stocks and were having to judiciously mix it with 100LL to eke out their supply. Happily they have now found someone willing to refine some for them.

With 100LL, I think the problem won’t be so bad. The USA has thousands of piston engined aircraft using 100LL, so a substitute will be found (even if extra additives have to be put in on the more powerful engines – one only has to think about the cocktails they use to torture Merlins at Reno to see this). The whole GA community won’t be converted to diesel power, nor will they accept being grounded!

I think at the start of WWII, British aircraft, certainly, were using lower octane fuel. Only later was the higher octanes available from the US, so it is possible to use a less volatile mixture. Also, vintage aircraft today are not subject to operational requiremnts they had in wartime to maximise their combat performance. Hopefully, long term we should be OK.

YR

I think the main problem to future operation of piston-engined warbirds will be a lack of suitable fuel. Correct me if I am wrong, but I believe that for example the RR Merlin was designed to use 130 octane fuel but now has to settle for the only aviation petrol available today, namely the 100 octane AVGAS 100LL. This seems to be OK as long as care is taken with the power settings, but what will happen when AVGAS 100LL is no longer available? This is a real threat in my opinion; it contains more lead than any automotive fuel ever did (which doesn’t please the environmentalists) and the demand is decreasing (which doesn’t please the oil companies). In Africa, and even in Italy, it is already becoming difficult to get AVGAS 100LL, and whether a replacement fuel will suit a fire-breathing Merlin or P&W R-2800 gives me cause for concern.

An interesting thread. I was at a talk last night by Charlie Brown at North Weald on warbird flying.

He made a very similar point about the BBMF long term. RAF pilots today are not trained on tailwheel aircraft any more, so any pilots continuing to fly the various aircraft operated by the flight will have to get converted onto type elsewhere. I suppose as everything else training-wise has been/is being privatised, they will just buy in the expertise from companies like Historic Flying, but it does make one think.

The whole question of currency is a knotty one. I know with DA renewals etc, there is a minimum set to try and ensure safety. But an experienced display pilot – Guy Bancroft Wilson – still managed to spin in the Kingcobra, and look how few hours he had on type.

There will always be pilots and investors with enough money to operate these type of aircraft. For a Spitfire you’re looking at about £2000+ an hour, realistically, and Charlie reckoned that the HAC MkV does about 35 hours a year.

Keeping current is fine if you’re on the circuit and can fly various aircraft with broadly similar handling characteristics. The problem comes with someone buying one for themselves, with relatively little experience , then getting into trouble. The Buchon is a particularly treacherous aircraft in this respect, apparently. I know HF will only sell you a Spit if they train you to fly it – hence the PV202 rebuild.

But all of us who fly know only too well that the time we flew the most was when we were learning (unless we go on to make a career of flying). From then on it’s a question juggling flying currency and cash to keep safe. And believe me, you do get rusty very quickly, especially on compex aircraft!

I would prefer to see these glorious old aircraft keep flying. But if it means putting them in the hands of pilots that aren’t really up to it, I’d rather they stayed on the ground.

YR

At the end of the day it’s all down to money, if the guys left at the likes of TFC and OFMC can afford to carry on operating them then they will continue. Personally i think OFMC will continue as long as Breitling carry on sponsoring them and they do the occasional movie, as OFMC’s fleet earn a living. TFC is privately owned and rarely flown, therefore it would be down to Nick and anyone else financially connected to them, to keep going. I believe once Stephen passes on we’ll probably only see half the collection fly one year the other half the next.
Hopefully i’m wrong.

Hmm, some very deep thinking going on there Ant. You alright old son, or was the witching hour starting to get to you? 🙂

I think you are brining up a lot of very valid points though; it’s just a shame that I’m due on a conference call in fifteen minutes and so haven’t really got much of a chance to get into this one. Ho hum. What I would say is that someone once said something to me that really made me think. I’m pretty sure it was Tim Moore talking about the Beaufighter, but whoever it was said something along the lines of: “Yes, I own it, and it’s registered to me, but it was here before I was, and all things being equal it’ll be here after I’ve gone. So really, I’m just it’s current custodian.”

Now, I find that to be a very interesting perspective, which makes a lot of sense when you really think about it. Take Spitfires and ex-Spitfire pilots for example. Over the last 10 / 20 / 30 years, the number of airworthy Spitfires has steadily increased, while the numbers of pilots who flew them operationally has decreased. You can’t stop the march of time. But by preserving the aircraft that we have, and by caring for them as if they had an identity of their own, we can do our level best to ensure that they’ll be there for our children, and theirs, and so on.

Good thread, Ant, I reckon it’ll provoke quite a bit of discussion – and thanks for distracting me from the irrelevances of the working day… 🙂

Stephen Grey has a son who is actively involved in The Fighter Collection, I presume he would take over in the future?

Blimey Ant have you been on the gin ? take a bit more water with it next time. Here we are on the verge of another splendid season of delights and you are getting all moribund and morose. Lets not wish our (and others) lives away old chum !!