Sodium Filled Intake Valves

[modelmaster2001]

What was the first aircraft engine to use sodium filled intake valves to control overheating?

 

[GrauGeist]

I believe it was the Pratt & Whitney R-2800 and it was the exhaust valves.

 

[swampyankee]

Wright R-1750, in 1926: Wright R-1820 1 - Balance Restored Corte Madera http://www.enginehistory.org/Piston/Wright/WrightR-1820.pdf

 

[Michael Hope]

I believe it was the Pratt & Whitney R-2800 and it was the exhaust valves.

The Bristol Pegasus Radial was flying in the Swordfish with the sodium exhaust valves before the R-2800 was even flown. But nor before the Wright engine.

 

[XBe02Drvr]

Wright R-1750, in 1926: Wright R-1820 1 - Balance Restored Corte Madera http://www.enginehistory.org/Piston/Wright/WrightR-1820.pdf

And that pendulum counterweight is why Wright engines clatter and vibrate so much at idle. They sound and act like they're trying to shake themselves to pieces. Willy Victor, the EC121 that used to base with us, would shudder and vibrate like a very low frequency tuning fork with its 3360s idling.
Cheers,
Wes

 

[GrauGeist]

The Wright R-1750 engine didn't have sodium filled valves from the onset, it was when it was developed to 1823 cubic inches during the "F" model stage in the mid-1930's, that it received Heron's valves.
The P&W R-2800 was in development during this time, so going from memory, I couldn't recall which engine got the sodium valves first.
Heron applied for the patent around the mid-20's, a few years after he moved to the U.S. from Britain, but I believe it was several years before his patent was approved and he perfected the process. So the valves would have been available to manufacturers by the early/mid 1930's.

By the way, Heron also developed the improved cylinder for the radial and was also the grandfather of high-octane fuel - brilliant guy.

 

[Simon Thomas]

The earliest engine I could find that had sodium filled exhaust valves was the Wright J-5 Whirlwind of 1925.

However the question asked was regarding sodium filled inlet valves. The only engine I know of that had sodium filled inlet valves was the Allison V-1710, and I am unsure if that was all of them or just specific models.

Edit: I concur with your assessment of Sam Heron - does anyone know of a good biography on him?

 

[swampyankee]

Since the incoming mixture is going to be fairly cool, only a hundred Celsius or so, what benefits would sodium-cooled intake valves provide?

 

[pbehn]

Since the incoming mixture is going to be fairly cool, only a hundred Celsius or so, what benefits would sodium-cooled intake valves provide?

That is cooler than the coolant in many WW2 aviation engines.

 

[Shortround6]

While the intake valve does get cooled by the incoming charge it may be hotter than 100 Degrees C, the other problem is that much of the head surface is cooled by the coolant behind it and the valves have to transmit the heat up through the valve stem to the valve guide. Works pretty well for low boost engines but high boost engines????


I would note that by 1941 the Americans were using sodium filled exhaust valves in such powerhouse engines as the Continental R-670, the Lycoming R-680 and even the Ranger 6-440 six cylinder inline engine.

 

[Steve Hnz]

This Wikipedia article has a list of publications including an autobiography, hopefully you can track something down, I guess I know him as the designer of the engine type in my old Ford Escort 1600.
For Simon Thomas, haven't got the hang of quoting yet.

 

[Carl]

Engineering tests indicate a sodium filled exhaust valve drops the valve temperature at the crown 30 degrees C at cruise power. The cost may be high but worth it. Does anyone know what company actually makes these valves? Lycoming buys them from someone else.

 

[Deleted member 68059]

Since the incoming mixture is going to be fairly cool, only a hundred Celsius or so, what benefits would sodium-cooled intake valves provide?

Indeed, fairly minimal benefits, the valves need cooled in order to resist corrosion and weakness which are strongly influence by the alloys, which got a lot better as time went on. The second benefit of keeping the valves cool is knocking, you dont want hot valve heads to initiate pre-ignition. However once you`ve got sodium cooled exh valves, the inlets are already running cooler than the exh valves even without any sodium - so making the inlets EVEN colder will contribute basically nothing to increased knock resistance.

Since the heat input into the exh valves is very considerably higher than the inlets (i.e. when they are opened) they will always be the hottest valves, and hence since sodium cant cool them MORE than this difference between inlet and exh valves, its basically nearly pointless to use sodium cooled inlets, as then you`ll just have the same temperature difference between inlet and exh valves, but at a lower absolute level.

Some actual data on INL and EXH valves with and without Sodium filling is below (data is from Honda F1 engine programme published in 2009)

INL Valve (temp Deg C with and without sodium filling)
718>544
(1324>1011 F)

EXH Valve (temp Deg C with and without sodium filling)
840>737
(1544>1358 F)

One benefit from doing this on the inlet valve is increased fatigue life if you are really pushing the valve weight (i.e. making as thin and light as possible).

 

[Carl]

Good points as to auto valves. My application is to a 9 cylinder, air cooled, radial aircraft engine with a maximum RPM of 3,000. During WWII nearly all aircraft engines had sodium filled exhaust valves. It was not just the stem but the inside of the head of the valve also. In addition to reducing the valve temperature 30 degrees C. it allowed higher head temperatures. The only downside is increased coking of the oil between the guide and valve. The addition of scrapers on the stem solved it. Today I know only of Lycoming selling these valve for their high horsepower engines. I am invovled in overhauling the Russian M-14P engine that is no longer made in Russia. We are running out of valves and need a new supplier.

Thank you for your input and time.

Carl