Dennis
Compression Test
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Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
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From: Colorado Springs Colorado
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Compression Test
So, with the help of a friend today, it took us 6 hours to remove all 24 spark plugs in both engines and run a compression test. Compression in each cylinder was between 65-76 psi.
Oh BTW, this wasn't in my '66 L79, but the WW II P-38 and those great 1400+ HP Allison V-12 engines
What a great day!
Oh BTW, this wasn't in my '66 L79, but the WW II P-38 and those great 1400+ HP Allison V-12 engines
What a great day!
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Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
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From: Colorado Springs Colorado
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Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
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From: Colorado Springs Colorado
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When my dad started working on planes he started with the P39 then 51's and finally P47's, but they were in daily use when that happened. That is a sweet plane there. Colling's foundation was here a couple weeks ago. The brought the 17, 24, two seat mustang and the Huey. When they were leaving the 24 had to abort take off. Found out the next day they needed a new prop blade.
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Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
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When my dad started working on planes he started with the P39 then 51's and finally P47's, but they were in daily use when that happened. That is a sweet plane there. Colling's foundation was here a couple weeks ago. The brought the 17, 24, two seat mustang and the Huey. When they were leaving the 24 had to abort take off. Found out the next day they needed a new prop blade.
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That is awesome. I've never seen a 47 in flight. My dad was a crew chief in WWII and his thunderbolt was a razorback. I have my mom and dad's wedding picture in a frame he made out of JU88 propeller tip that he cut off one that was flipped over from a bomb blast when they captured the airfield.
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That P-38 motor looks like a plumbers nightmare.
I have seen several Allisons, and even Merlins on stands, but never hooked up and ready to run.
Does that Allison have the big 2 barrel Stromberg with ~4" throttle plates, or is it injected?
Doug
I have seen several Allisons, and even Merlins on stands, but never hooked up and ready to run.
Does that Allison have the big 2 barrel Stromberg with ~4" throttle plates, or is it injected?
Doug
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Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
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Bud Anderson was at the museum for an event this past March. This P-51 was flown in for the event as it is painted to replicate the one he flew in WW II and will remain in the museum until late April.
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Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
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Doug, you’re correct. It took 2 of us almost 6 hours to remove all 24 spark plug wires, spark plugs and do a compression test on each cylinder. We didn’t reinstall the plugs as they each needed to be cleaned and tested first, which was probably done today. I’m not 100% certain, but I think it has carburetors. I’ll check next week.
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Do the engines still have the second stage turbosuperchangers mounted on the boom behind the engines? They add a lot of complication and aren't necessary unless you want to go over 15-20K feet.
The turbos didn't add any boost at takeoff/low level, so rated sea level take off power is with just the first stage centrifugal supercharger (that I think is two speed), and the turbos could maintain sea level take off power up to about 25,000 feet.
BTW aircraft engine takeoff power is rated at absolute manifold pressure, so if it 60" Hg, boost is about 30", or about one atmosphere, 29.92" Hg, 14.7 psi.
Unlimited racers run up to 120" and they blow up a lot of engines. It's amazing that there are any Allisons or Merlins left.
Duke
The turbos didn't add any boost at takeoff/low level, so rated sea level take off power is with just the first stage centrifugal supercharger (that I think is two speed), and the turbos could maintain sea level take off power up to about 25,000 feet.
BTW aircraft engine takeoff power is rated at absolute manifold pressure, so if it 60" Hg, boost is about 30", or about one atmosphere, 29.92" Hg, 14.7 psi.
Unlimited racers run up to 120" and they blow up a lot of engines. It's amazing that there are any Allisons or Merlins left.
Duke
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Those were war machines and not expected to reach overhaul limits. Plus the military had the budget to just replace rather than overhaul. Plus the military had full time maintenance crews that didn't collect overtime pay but could be forced to work it.
Seems surprising so many went to scrap so fast after the war but long service was not part of their design. Not like a corporate KING AIR or a PILATUS aircraft of today. Maintaining a P38 for a 1000 hours is whole lot more expensive. I don't have statistics to prove it but maintenance hours to flight hours ratio is huge compared to most GA aircraft.
What I'm saying is just because it has wings and flys doesn't mean you can maintain it as easy as a piper or cessna let alone a corvette.
Seems surprising so many went to scrap so fast after the war but long service was not part of their design. Not like a corporate KING AIR or a PILATUS aircraft of today. Maintaining a P38 for a 1000 hours is whole lot more expensive. I don't have statistics to prove it but maintenance hours to flight hours ratio is huge compared to most GA aircraft.
What I'm saying is just because it has wings and flys doesn't mean you can maintain it as easy as a piper or cessna let alone a corvette.