Warbird Information Exchange

It's not about fuel. Remember these are aircraft for 'play' or commemoration, not fighting wars.

Few warbirds fly with the loadings or equipment that the would have done in their primary service. (There's an inverse ratio of 'activity' between the heavilly restored fully complete with original widgets warbirds, which are flown careful, and limited, by and large, against the stripped back, gunless hot-rod fun 'planes.)

Apart from at Reno, there's no good reason for pushing the airframe, engine (and pilot) as hard as they were in wartime, where there was a supply-chain to back up wastage, including, we remember here, of aircraft and crew.

No warbirds fly at wartime operational heights, with oxygen, for instance.

Sure, you can make more noise and speed with the aircraft by pushing the throttle; but your costs go rapidly up straightaway, and for Americans, Uncle Sam's not funding that this time. So there are a few who fly hard at times, but the majority don't.

Thanks to Reno, there are options for going as fast (low down) as W.W.II but the engine (and airframe) consumption rate reflects that. And don't forget that pushing the envelope cost lives back then; doing it now would increase the number of warbird accidents.

Muddy; Lead (euphemisms Ethyl, TEL, tetraethyllead) helped reduce 'knocking' and allowed greater power out of engines, and 'lubricated' things like valves to avoid the valve head leaving parts on the valve seat - all at the great cost of literally putting cumulative heavy metal poison into every man, woman and child on the planet.

I'm sure there are those here who can explain the lead fuel additives benefits better than I can, meanwhile if you'd like to see how amazingly we can screw something up on a global-effect level by believing a business when they tell us something's harmless, may I introduce Thomas Midgley Jr and the Ethyl Corp?

http://en.wikipedia.org/wiki/Thomas_Midgley,_Jr.

Just a few thoughts...

To be fair James, I think there's a little bit more to it than that. Where the power issue becomes critical for some airplanes is in the case of multi engine aircraft operating with an engine out. At high density altitudes I would expect that something like an A-26 or a B-25, or a drop tanked P-38 could easily become something of a marginal proposition due to the inability to pull max power from the good engine due to the poorer quality fuel. And lets not forget the working radial engined airplanes out there still like the DC-3, DC-4, DC-6, and C-46. Having an iced up C-46 with an engine out and a load in the back was never a great situation even on 115/145, but on 100LL...

The answer to the original question is -yes- these vintage engines will run just fine at fully rated manifold pressures on the available 100LL fuel. As some have mentioned already, it was designed to be a direct replacement of the 100-130. In fact there have been long standing questions and discussions surrounding whether or not it actually is. I believe there is enough scientific data to suggest it is -in a laboratory setting- but real world performance dictates otherwise. Many operators and engine builders will go with richer jetting, retard the ignition timing, and in the instance of liquid cooled engines, run them several degrees cooler. All of these variables allow the engine to safely operate at the “Advertised” manifold pressures however, the trade off is the engines make less over all power.
There are plenty of high quality unleaded fuel alternatives on the market that would be very suitable from anti-knock performance perspective but they are expensive and do nothing for valve lubrication which is critical in engines without hardened valve seats. Most of the engines we’re dealing with here do not currently have hardened seats. Research has proven TEL’s lubricating effects on these surfaces. Brewing one’s own 100LL by adding tetra-ethyl lead is not an option since it is readily absorbed through the skin and is lethal to the touch in very small amounts.
James has it spot on. These old warriors fought their battles long ago and have nothing more to prove. The harder we push them the more parts we break. The more parts we break the sooner flying them will come to an end. I’d rather see a P-38 loafing around at cruise power than see one sitting on the ground collecting dust because there were no parts to make the engines airworthy. As much as I love racing in all forms, including Reno, I have serious heartburn about the destruction of irreplaceable vintage parts year after year.

so when we go to airshows and see a corsair or a mustang, are they flying the aircraft maybe at 50-75% of what it's really capable of? I've seen some great mustang demos and it seemed like it was screaming thru the sky. I always wondered if he was really pushing that plane to see what it could really do. Great Answers so far guys!

It's a similar case from what I have read and seen, that in a Merlin-powered Mustang, pilots tend to use anywhere from 45-50-55-in MP - the original in-service manual will tell you to use 61-in MP, but that seems to be more than what is needed to get a Mustang quickly into the air, especially one that is not loaded for combat-use of course, thus there isn't need for it. In all other realms of flight - climb, cruise climb, and normal cruise - settings used are often times the same as what would have been used in the service, if not slightly lower to conserve fuel in cruise.

For display purposes, I have heard Mustang pilots use as much as 46-in MP & 2700 RPM in an acro performance, the same as max climb power, or 42in MP & 2500 RPM, or 40-in MP & 2400 RPM depending on the nature of the display, which is right around max continuous power.

so when we go to airshows and see a corsair or a mustang, are they flying the aircraft maybe at 50-75% of what it's really capable of?

I am only in my 20s but someday I will fly it at airshows. I am getting rich really fast writing software and so I can afford to do really stupid things like put all my money into warbirds.