Octane Rating

[GregP]

In one of the threads below, it was mentioned that some Reno engines were running 180 Octane fuel. I said I had never heard of 180 Octane fuel and offered to ask Steve Hinton over this weekend.

Unfortunately, Steve was not at Chino yesterday, so I didn't get to ask him. I will ask, but it obviously must be when he is there.

None of the pilots I DID see had ever heard of 180 Octane fuel, and several said that level wasn't even on the scale as far as they knew.

Still, technology development today makes me hesitate to say it does not exist on my own.

Again, when Steve is present at Chino on a Saturday, I'll ask him about it, possibly next weekend ... it depends entirely on Steve's schedule. We still have some of the aircraft from our recent airshow at the Museum, and they have to be returned to the owners.

He was out on a P-40 flight to Boise, Idaho yesterday, and may well have to return the two Tigercats and the P-63 next weekend. We also have to get the Grumman Duck back to Arizona (at 100 mph or so), and there are several other nice aircraft that also need to fly away home.

So ... I'll get back with this thread when I find out. meanwhile, I'll assume that a 180 Octane perforamnce number may be possible from fuel. If so, I'm not sure it could be called "gasoline," but that, too, may be true.

[Red Admiral]

Its a pretty notional scale when it comes down to it. Even the the gasolines with numbers over 100 have large amounts of TEL added. However, it forms a useful comparison as other fuels can also be used. Ethanol is around 112PN. Highest I'm aware of is Triptane at around 250+ but can't really be used in an actual engine.

Coupled with lots of ADI you can achieve very high boost levels.

[Kutscha]

Any number over 100 is a Performance Number.

[Wuzak]

In one of the threads below, it was mentioned that some Reno engines were running 180 Octane fuel. I said I had never heard of 180 Octane fuel and offered to ask Steve Hinton over this weekend.

Just quoted an article from the web....

But I do know that RR were playing with PN160 fuel with extra TEL when it was getting the big numbers out of the RM.17SM.

[GregP]

Hi Wuzak,

It could be that the 180 number exists.

If so, then we could run maybe 16.5 : 1 compression ratio in ours hot rods and still live! Boy, would that be cool ... until it came time to pay for all the broken parts ...

[Wuzak]

Hi Wuzak,

It could be that the 180 number exists.

If so, then we could run maybe 16.5 : 1 compression ratio in ours hot rods and still live! Boy, would that be cool ... until it came time to pay for all the broken parts ...

Imagine just paying for the fuel.....

[GregP]

Well, Steve Hinton finally made it back to Chino after some travels. I asked him about Avgas as promised.

He confirms what I thought; the highest Octane Performance Number he has heard of is 160, and he doesn't believe the 160 number. He says it is a nebulous number that starts with 100-Octane fuel and then adds many chemicals to it to bump up the ability to function under pressure and temperature.

ALL high Octane gas starts out as about 100 Octane and then has additives thrown in in specific proportions. The two-value Octane ratings are rich and lean, not anything more. Steve said the so-called 160 Octane gas runs well, but not demonstrably better than other high Octane gas that has been used before.

He has never heard of 180 Octane anything to run in a gasoline engine.

By way of exerpience, I have never heard of it either, and I have raced cars, boats, motorcycles and radio control model airplanes. Never raced a full-scale manned aircraft, but Steve has and has won a US National Air Racing Championship at Reno in the Red Barron P-51 Mustang. He starts Reno every year in the Planes of Fame T-33 and mostly flies everything that races at one time or another, usually after some repair or modification.

In the last several months, we have had September Pops, September Fury, Strega, and Dago Red at Chino, along with Tigercats, Skyraiders, our own coll,ection of WWII aircraft, and a few other "for sale" units being prepped for new owners. Steve Hinton and his son, Steven Hinton Jr., have flown most of them. Steve Jr. will be flying Strega this year at Reno.

Offhand, I'd say that if 180-Octane gas exists, one of the Hintons should have known about it.

[Kutscha]

I will say it again Greg. Any number is a Performance Number (PN). Octane rating doesn't go past 100. If power produced by pure fuel is 100, then the addition of lead will let the power increase up to 45%, thus the performance number is 145.

[GregP]

Did I not say Octane Performance Number? The number 160 or 180 is directly related to Octane number since it is referenced to 100-Octane fuel.

Read the last two words above and my post below, I think everyone understands it is a performance number, including me.

Never head of 180, like I said below. Doesn't mean it doesn't exist, and I did not claim that.

It means that 4 or 5 of the top pilots I know, all warbirds pilots, and some who have been National Champion at Reno, and who are still involved at Reno, haven't heard of it. Neither has one of the best engine builders in the U.S.A, Joe Yancey of Yancey's Allison. He also builds Merlins. And still hasn't heard of a 180 fuel, even in Europe.

Tell you what, I'll look for it at Reno this year. It isn't very far away inot the future and, if it exists, it SHOULD be at Reno if somone is going to actually race with it.

[Sid447]

[QUOTE=GregP;25649]
.......snipped!.............In the last several months, we have had September Pops, September Fury, Strega, and Dago Red at Chino, along with Tigercats, Skyraiders, our own coll,ection of WWII aircraft, and a few other "for sale" units being prepped for new owners. Steve Hinton and his son, Steven Hinton Jr., have flown most of them. Steve Jr. will be flying Strega this year at Reno.
QUOTE]

Hi GregP,

Is Dago Red in for Reno this year?

Is anything left of the old Red Baron?

Steve.

[GregP]

Hi Sid,

The only parts left of the Red Baron are bits of the canopy and the few new things they find every year when they go to Reno.

Dago Red has been bought by a private party and it is now at Chino in some pieces. Not from a crash, but from disassembly.

They will probably race it again, but probably not this year unless a miracle can happen in a month. I'm trying to get on the project to help out with some sheet metal ... we'll see. If I do get on the project, I may or may not be able to tell about it or post pics. It all depends on the wishes of the owner. He may be secretive and may not be, and I may or may not be able to get on the team.

In any case, it should be at Reno in the future. I don't know enough about it yet to predict when.

Steve Hinton Jr. is slated to race Strega this year, and we hope he'll win Gold. Still, there are some really fast aircraft out there, not the least of which is Rod Lewis' Rare Bear.

In any case, Reno will be FUN! And fast!

My reply below, when I read it in the light of a new day, seems sarcastic although that was not my original intent. I WILL keep my eyes out for special fuel when we go to Reno. Who knows, maybe the winner will be flying the special fuel that started this thread.

[GregP]

OK everydoby, I spoke with Steve Hinton Jr. today and ask him about the ongoing discussion. If there is ANYONE who would know, it is this guy. He just got back from Reno pylon school, and was there to get some more time on the course, not to qualify. He will fly Strega this year in the Gold class. Naturally, we all want Stevie to win BIG time. At the school, they used a more or less stock engine for some flying time at speed and at low altitude.

According to him, the highest performance rating gasoline available is about 160. However, he says you can take the 160 number gasoline, add Manganese in EXACTLY the right quantity and get close to a 180 number ... IF you get it just right. If you add too much, it falls off rapidly along with the engine.

He says there is no commercial 180 available; anyone who is flying it makes it themselves. Many throw out a large quantity of otherwise expensive normal high-octane gasloine because they added too much Manganese. Doesn't takke too many errors to cost a lot.

Stevie also confirms that there are one or two Merlins out there that can make 3,600 - 3,800 HP at the crank at 3,300 to 3,400 RPM, even after running the second stage supercharger, with the gearing that is available. Not many, but they DO exist.

With an 85% efficient prop, it comes down to 3,250 HP. So maybe we are all talking the same language, just not including prop losses. He says that not many Merlins can live at that power rating for long, and he refused to say what HP they DO make. I'm sure you can understand, especially just before Reno.

Apparently I have been talking with people who were all taking HP to the prop after efficiency losses. If you drop the diameter, the plane accelerates to about 450 mph rapidly and then hits a speed wall. If you leave the diameter out there, you can creep up on 500 mph with judicious use of RPM to keep the prop tips subsonic or at LEAST transonic, and actually get to 500+ mph in a highly modified Mustang. Of course, the airfoils and the airframe and prop section are NOT stock. Neither is the drag coefficient. Most genuine 500 mph racers have ADI, water spray bar, home brew fuel, and a short engine life.

Nobody knows the drag coefficient of the Reno racers due to the cost to obtain it in a wind tunnel.

In case you don't know, the R-3350 in Rare Bear can belt out 4,400+HP in race trim with the corect gasoline ... but there IS cooling drag.

So ... the entire point is to make the last lap with the engine running at full song and full power and speed. The rest of the laps are used to build up to the fast , full-speed laps.

When the race is done, some racers fly home at reduced power and some change the race engine for a get-home engine and fly home at mormal warbird cruise speeds with the exception of the peculiar systems such as total loss compressed air landing gear extension in some bear-type racers and other things like, perhaps, no flap landings that MUST be 3-point or the prop strikes the runway.

Strega doesn't have that problem, being more friendly to operate than some.

So, all you Merlin lovers, there IS a 3,000+ HP Merlin out there running at Reno, just not very many and not for much time at full power. These Merlins can be counted on one hand.

Most of the rest are as I described earlier. 2,500 to 2,950 HP at full rattle, with some degree of risk in running at that power for more than a lap or two. Many times, it is the cooling system that collapses rather than the engine.

So, the 180-Octane number (actually a performance number) MAY be true but, if so, is made by each individual team. They do not measure it in a chemistry lab or with a normal Octane engine. They check by blown engines and lap times, and estimate it. People are notorious in over-estimating, and nobody will give anyone else a sample of their home-made fuel brew lest a competitor find out what they do to make it themselves.

If anyone has the money to rent a full size wind tunnel complete with aeronatical engineers and technicians, they'd LOVE to know the drag coeefficient of Strega. Meanwhile, National Championship Trophies are the goal. Check back in Septembner after the races.

Methinks they KNOW the drag coefficient but are reluctant to share. if you know your horsepower, the RMP, the speed, and well-estimated prop losses, you can back into drag coefficient given the observed speed, altitude and temperature.

However, the LAST thing the team would want is to share that data with the world in absolutely in any forum.

Cheers! You 180 performance number guys might be right, but you could never tell unless you test it every step along the way.

Best regards, - Greg