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Classic Wings Magazine WWII Naval Aviation Research Pacific Luftwaffe Resource Center
When Hollywood Ruled The Skies - Volumes 1 through 4 by Bruce Oriss


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PostPosted: Wed Dec 15, 2010 11:25 am 
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This came in on the propeller making group I subscribe to, talking about supersonic propeller blades. I couldn't believe my ears .... as it were. Thought some of y'all might get a kick out of it too.

From: http://en.wikipedia.org/wiki/Republic_XF-84H

The XF-84H was quite possibly the loudest aircraft ever built, earning the nickname "Thunderscreech" as well as the "Mighty Ear Banger".[13] On the ground "run ups", the prototypes could reportedly be heard 25 miles (40 km) away.[14] Unlike standard propellers that turn at subsonic speeds, the outer 24–30 inches of the blades on the XF-84H's propeller traveled faster than the speed of sound even at idle thrust, producing a continuous visible sonic boom that radiated laterally from the propellers for hundreds of yards. The shock wave was actually powerful enough to knock a man down; an unfortunate crew chief who was inside a nearby C-47 was severely incapacitated during a 30-minute ground run.[14] Coupled with the already considerable noise from the subsonic aspect of the propeller and the dual jet turbines, the aircraft was notorious for inducing severe nausea and headaches among ground crews.[10] In one report, a Republic engineer suffered a seizure after close range exposure to the shock waves emanating from a powered-up XF-84H.[15]

The pervasive noise also severely disrupted operations in the Edwards AFB control tower by risking vibration damage to sensitive components and forcing air traffic personnel to communicate with the XF-84H's crew on the flight line by light signals. After numerous complaints, the Air Force Flight Test Center directed Republic to tow the aircraft out on Rogers Dry Lake, far from the flight line, before running up its engine.[11] The test program did not proceed further than the manufacturer's Phase I proving flights, consequently no USAF test pilots flew the XF-84H. With the likelihood that the engine and equipment failures coupled with the inability to reach design speeds and subsequent instability experienced were insurmountable problems, the USAF cancelled the program in September 1956.[16]

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PostPosted: Wed Dec 15, 2010 11:45 am 
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The link with the soundbite is interesting. What a monster.

And yet awesomely cool!

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PostPosted: Wed Dec 15, 2010 12:42 pm 
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Boeing also fell for the turbo prop bomber by building 2 B-47D's equipped with Curtiss-Wright T-49 engines on the inboard engine pylons. They got one up to 597 MPH, but they had the same sonic issues and dogs and people for miles around were queasy whenever the engines were run.
An article in a recent aviation history magazine had an article on the 'screech' and apparently one of the only two guys to fly them (both civilians) told one of the project engineers (who was a pretty good sized individual) after his first and only test flight, 'I'm NEVER getting back in that thing, and you aren't big enough to make me'

I remember as a kid, the 'screech' did have a staring role in one issue of 'Steve Canyon' comic books

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PostPosted: Thu Dec 16, 2010 11:36 pm 
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Does anyone have information as to how loud it was (i.e decibels) ?? I went thru the various links on Google and could find no reference as to the measured intensity.


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PostPosted: Fri Dec 17, 2010 12:11 am 
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ever been close to a t-37 tweet or harrier??? you'll be learning sign language very soon!!!

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PostPosted: Fri Dec 17, 2010 4:02 am 
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An EA-6B at Hi-Power will loosen fillings..DAMHIKT!

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PostPosted: Fri Dec 17, 2010 5:31 am 
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jdvoss wrote:
Does anyone have information as to how loud it was (i.e decibels) ?? I went thru the various links on Google and could find no reference as to the measured intensity.

After a quick look, I've not found anything. Air Enthusiast 48 (December 1992-February 1993) has an article - 'Thunderscreech' - Republic's XF-84H turbo-fighter by Ed Davies, which may cover it, but annoyingly, it's one of the issues I'm missing.

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PostPosted: Fri Dec 17, 2010 11:36 am 
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In order to make it heard while parked on the ramp @ an airport among all the din and noise, Douglas equipped the DC-10/MD-11 with an APU fire horn located in the aft portion of the right hand wing to body fairing and about 10 feet above the ramp surface, it went off @ a dizzying 180 dba or the equivalent of seeing the Space Shuttle launch from just under 2 miles. A normal conversation is around 80-85 dba and decibels are like earthquakes a .1 increase is logarithmic or magnified by a factor of 10. I understand from some who have heard one go off, they said they could almost see the noise!

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