3-blade prop on T-6 question

hahnej · **Posted:** Tue Jan 03, 2012 9:27 am

I have seen a couple T-6's and hybird T-6 models that have been re-engined with the R-1340 AN-2 engines, which have the geared nosecase and turn a 3-blade prop. What exactly does this do performance-wise. I noticed as well that the AN-2 engines are rated at 550hp vs 600 for a 'normal' 1340.....? Just curious.

51fixer · **Posted:** Tue Jan 03, 2012 10:04 am

hahnej wrote:

I have seen a couple T-6's and hybird T-6 models that have been re-engined with the R-1340 AN-2 engines, which have the geared nosecase and turn a 3-blade prop. What exactly does this do performance-wise. I noticed as well that the AN-2 engines are rated at 550hp vs 600 for a 'normal' 1340.....? Just curious.

Actually the typical AN-1 series of the 1340 as fitted to the majority of T-6s is 550 HP continuous and 600 HP takeoff at 2250 RPM and 32" MP.
The AN-2 is the same 550 HP continuous and 600 HP at take off at 2250 RPM and 36" MP. The AN-2 has a supercharger that runs at a higher speed IIRC along with the gears in the nosecase that slow the prop shaft.
My guess is you would need the FAA to sign off on a Field Approval to install the AN-2 in a Standard Category T-6.

expat · **Joined:** Mon Aug 08, 2005 7:51 am **Posts:** 68

would it make them quieter with 3 blades ?

cooper9411 · **Posted:** Tue Jan 03, 2012 11:23 am

expat wrote:

would it make them quieter with 3 blades ?

Not much.

51fixer · **Posted:** Tue Jan 03, 2012 1:35 pm

expat wrote:

would it make them quieter with 3 blades ?

Actually they are a little bit. More of a different sound.
I believe the ratio is 3:2 so the prop turns 1/3 slower than the AN-1, around 1500 RPM when the engine is 2250 RPM at take off..
Many of the AN-2 installs on modified airframes have custom exhaust with individual or multiple short stacks rather than a collector. That changes the sound.
Otherwise you get the roar without the prop buzz of a standard T-6 if equipped with the standard exhaust.
I was involved with a rebuild many years ago for someone in Switzerland. They kicked him off the airport due to noise of his T-6. He sold that one and bought a project T-6 that was built with an AN-2 so it would be a little quieter.

Matt Gunsch · **Posted:** Tue Jan 03, 2012 1:36 pm

expat wrote:

would it make them quieter with 3 blades ?

extremely quiet when compared to a standard 6, a good friend of mine operated his SNJ with a geared engine out of Sedona for years with no noise issues. When you hear a 6s prop snarl on takeoff, it is beating the air and not very efficient, a 3 blade prop does not have that issue.

As far as performance, they are a bit faster, and are great in formation, esp on the outside turns as that prop really pulls. '

His plane was done on a field approval and his paperwork has been used for several other conversions, oh and it is Standard category

51fixer · **Posted:** Tue Jan 03, 2012 1:47 pm

FAA Type Certificate Data is here-
http://rgl.faa.gov/Regulatory_and_Guida ... L/5E-2.pdf
I know someone who is overhauling an early 1340 for a Lockheed Vega they are rebuilding.

hahnej · **Posted:** Tue Jan 03, 2012 8:03 pm

Thanks!

The Inspector · **Posted:** Tue Jan 03, 2012 9:52 pm

51fixer,
Did that airport authority have any noise issues with CESSNA 180/185's swinging a 2 bladed 72 inch seaplane prop?

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3-blade prop on T-6 question

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