Thread: Merlins

I used to run my Dodge Challenger with 426 Hemi on 115/145 Avgas. The guy who owns it now complains about not being able to buy adequate fuel. He told me the airport fuel dealers will only sell it into an aircraft. He uses 98 unleaded and mixes benzol or toluene or some such one to four. He says he will get lower compression pistons when he has to overhaul. It currently has 12.5:1 compression ratio. It is on restricted registration and gets occasional use on a Sunday.

[QUOTE=rick130;977201]Just what that famous laminar flow wing was designed for.
[QUOTE]

not quite correct, the laminar flow wing was a hang over from the XP51, this being designed as a ground attack aircraft needed a thick wing to be able to sustain the buffeting and some battle damage, this was also the reason for moving the glycol and oil coolers onboard rather than have them hanging of the wings ( spitfire) or under the chin P40) in trials the XP51 was some 22'mph faster than the P40 ( Allison powered)

If we are to compare a spit to a P51 i would sagest that the MK9 ( interim) and the P51 B ( razorback) rate of clime to the spit strait and level to the p51 until 18 000 feet when the spit pulled ahead. The higher the altitude the more Attitude the P51 needed ( hanging off the prop) in a dive the p51 was ahead with cooler flap closed, spit ahead with cooler flap open.
The P51 was a dog with full tanks, tail heavy and quite unstable, this alone killed many green and over confidant pilots. In short you could not clime fully fuled, put the nose up and she kept going up.

to compare civil military aircraft today is a bit off, lacking amour and armaments and in the case of the P51 all its fuel tanks.

the P51 had some other draw backs, the .5 browning would Jam at any negative G or over +3 G, stability problems after the razorback was dropped hence the little sharks fin. And optical problems. its no surprise that the OLD hands kept there older P51s. the only example of this with the spits was DB and then he didn’t want the 20mm cannons so they built him a 8 X 303 ship. But the spit never had the problems that the P51 had. But neither was it as great an aircraft as most believe. Most pretty sure but not the best.
Nor has the spit the real battle scars to mark its reputation.
If we were to look at the P40 ( of Australian interest) this is the only aircraft to fight though the war. Starting with a radial then supercharged V12. But there are many more examples that should be held in higher esteem than the spit.

oh the spit has a veering angle of attack along its wing length, the advantage of that was the wing root would stall before the tip

Originally Posted by isuzurover

You sure? Wikipedia disagrees:

I have not seen 100/130 for years - but I'm quite prepared to believe it is around in some areas. I remember there was a lot of angst when 100/130 was replaced by 100LL, not because of the octane rating - they are in fact the same - but because the low lead causes exhaust valve seat recession in some engines, particularly older engines that were designed to run on high lead 80/87.

But not really relevant to my point - 115/145, which the engines were designed for, has not been available for years (Actually some marks of Merlin were intended to run on 100/150, which allwed even higher boost and producing even more power).

John

Originally Posted by Brian Hjelm

About 1992 he told me it then cost about $150 of Avgas to warm up and taxi around Toowoomba airport, take of and do a circuit, land and taxi back to the shed.

Back in the late eighties the rule of thumb used to be $1500/hr to keep in the air for the high performance warbirds.
God only knows what it would cost now

Originally Posted by rick130

Back in the late eighties the rule of thumb used to be $1500/hr to keep in the air for the high performance warbirds.
God only knows what it would cost now

How the hell can anyone afford to own one???

As an aside, someone once told me that their were experiments using pure o2 in WWII to give aero engines a power boost - anyone know anything about that.

One of the wifes rello's owns a P-40 (Allison) and runs a restoration workshop in NZ. He's an old drag racing lunatic....anyway, the hourly operating cost of the Kittyhawk is around $5500. The bulk of that is insurance, fuel is the last consideration.

I can't imaging the cost of something with a 'real' engine, like a P-47 or Neptune. A plug change alone would be around 4 grand .

Makes running old Land Rovers look like a doddle.


Matt.

PS. No, I'm not in the will.........yet

Originally Posted by isuzurover

How the hell can anyone afford to own one???

As an aside, someone once told me that their were experiments using pure o2 in WWII to give aero engines a power boost - anyone know anything about that.

There were plenty, mainly the big radials played around with it.
Aircraft like the Corsair had water injection for high altitude cruse, I think they got an extra 50hp but at that altitude it had already dropped to 1980hp
Nos was a new thing as well, Allison played around with this a lot and was used extensively in boat racing post war.

Originally Posted by clean32

There were plenty, mainly the big radials played around with it.
Aircraft like the Corsair had water injection for high altitude cruse, I think they got an extra 50hp but at that altitude it had already dropped to 1980hp
Nos was a new thing as well, Allison played around with this a lot and was used extensively in boat racing post war.

Water-methanol injection is/was used in highly pressurised engines as an additional inter-cooler and for its properties in reducing detonation. Those WWII aero engines used it most commonly when "emergency military power" was used. The pilots called this putting the throttle "through the gate". Extra boost and extra charge cooling requires extra fuel to be supplied to the mixture, and further retardation of ignition timing. A big increase in output resulted. Detonation is always a major problem with pressurised engines once boost gets much above 8 psi over atmospheric at sea level. USAAF aircraft with this facility had a "tell-tale" that had to be reset externally after emergency power was used. The ground crew were thus aware of the pilot's indiscretion even if he was not forthcoming. USAAF policy was that all engines thus used had to be removed and dismantled for inspection and overhaul. EMP was only supposed to be used for short periods, 15 seconds typically. Corsairs and Thunderbolts had water-methanol injection, not sure of others. Some carried up to 50 US gallons of the mixture. I know nothing at all about the usage rate.