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Post by Tom/CalClassic on Feb 26, 2009 9:24:02 GMT -5
I think the big difference between the R-2800 and the R-3350 was that the former typically ran at TO powers around 2400 HP, while the latter ran up to 3400 HP. The higher power levels put extra stress on all components. While supercharger failures were a big problem on the 3350, other failures were also reduced if high blower was avoided. These days high blower is almost universally avoided for both engines. One reason is increased reliability, along with avoiding pressurization. The other is that the 100LL gas used today usually precludes it.  |
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Post by ashaman on Feb 27, 2009 9:58:17 GMT -5
These days high blower is almost universally avoided for both engines. One reason is increased reliability, along with avoiding pressurization. The other is that the 100LL gas used today usually precludes it. Are you sure? I mean, it's logical that nowadays the planes of the past era that remains in working condition are rarely brought above certain flight levels ( and so the high blower is rarely if at all used), even more so if one thinks that some of the planes we're talking about are considered historical, and as such treasured. But shouldn't the 100LL gas only preclude the use of high manifold pressures ( used mainly while taking off or going around), regardless of altitude, and being impervious to the use of regular manifold pressures at high altitude? If so, why should the 100LL preclude the hypothetical use of the high blower?  |
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Post by Tom/CalClassic on Feb 27, 2009 10:20:47 GMT -5
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Post by kstlmike on Feb 27, 2009 10:21:24 GMT -5
I've always been thankful that the 3350 engines on the simulation Starliner operate perfectly every flight! (.....and I've never had to spend a penny for either maintenance or fuel!) ..........Mike |
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Post by sunny9850 on Feb 27, 2009 21:20:33 GMT -5
From my discussions with my friend Joe who flew the DC-7 for AA in TransCon service it seems they had more trouble with the PRTs and not so much with the Blower.
I think the mechanics referred to them as "Parts Recovery Turbines"
The average TBO was somewhere around 700h/engine for these Airplanes he mentioned....they were pushed to the extreme to make the New York - Los Angeles flights within acceptable crew duty times.
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Post by ashaman on Feb 27, 2009 21:41:36 GMT -5
Well, I know it's just not permitted with the R-3350: From the FAA: "High impeller gear ratio: Operation not permitted with Grade 100/130 or 108/135 fuel." This does not make a lot of sense. I'm not doubting your words, just trying to be the devil advocate here. What about all the planes born before the advent of the 115/145 octane fuel engined R-3350? I'm speaking about the L-049/649/749, and even the B29? The L-049's first flight was in 1938, following all the sources I can find, and it had the R-3350, and it flew in high blower with a fuel that was probably of a quality even lower than the 100/130 octane ( mass produced from 41 forward, from sources found around). Was the prohibition of use of high blower with any fuel less than the 115/145 octane fuel limited to the Turbo Compound R-3350 then? |
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Post by Tom/CalClassic on Feb 28, 2009 10:19:49 GMT -5
Hi,
Yes. If you do a search at the FAA site I linked above for 749, you will see that the earlier R-3350's were designed to use 100/130 fuel, in both low and high blower.
Hope this helps,
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Post by Maarten on Feb 28, 2009 10:55:37 GMT -5
The L-049's first flight was in 1938 I'm afraid that is not correct. The very first Constellation, a C-69, first flew on 9 January 1943. The L-049 was the post-war civil version (several C-69's were actually converted to L-049 standard). The first production aircraft powered by the R-3350 was the Boeing B-29. First flight of this type 21 september 1942. The R-3350 didn't fly until 1941 but was still in testing stage by then. At Wikipedia there is some interesting information on the R-3350 family. See en.wikipedia.org/wiki/Wright_R-3350Cheers, Maarten |
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Post by ashaman on Feb 28, 2009 10:59:22 GMT -5
Hi, Yes. If you do a search at the FAA site I linked above for 749, you will see that the earlier R-3350's were designed to use 100/130 fuel, in both low and high blower. Hope this helps, It helps understanding. My educated guess based on the data discussed is that the most powerful of the non-TC line of the R-3350, the 2700hp and 2800hp versions ( used to obtain the 3250hp and 3400hp engines with the application of the PRT system), were not completely certified to work with 100/130 octane fuel, and this was inherited by their TC versions. While instead the 2500hp of the L-749, and below, were less exacting on their fuel. |
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Post by ashaman on Feb 28, 2009 11:01:17 GMT -5
The L-049's first flight was in 1938 I'm afraid that is not correct... Right you are, I confused the year of the start of the Constellation program with the first flight.  Forgive me?  |
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Post by Maarten on Feb 28, 2009 11:02:58 GMT -5
But of course I do. ;D
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Post by jesse on Feb 28, 2009 13:59:21 GMT -5
8-)Gee, are they that old? In 1938 I was only 15 years old. ;D
Jesse
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Post by ashaman on Feb 28, 2009 23:26:45 GMT -5
8-)Gee, are they that old? In 1938 I was only 15 years old. ;D Jesse My Grandpa ( father side) was 33.  My father was 3.  I was... to be born in 31 years.  Still like them. ;D |
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