14-12-2006, 22:52
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חבר מתאריך: 12.09.05
הודעות: 1,470
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נזכרתי שאוכל לקבל תשובה ממקור טוב ,בוגר קורס טייס של USAF ב WW2
בתגובה להודעה מספר 1 שנכתבה על ידי עמי60 שמתחילה ב "ראיתי בערוץ ההיסטורי תוכנית על WW2 בה דברו על מטוס הקרב P47"
להלן תשובתו שלא עונה בדיוק על השאלה .
Ami,
The P-47 was my dream airplane when I was a youngster. That was the plane
that was responsible for me to want fighter pilot training. I loved
the looks of that
plane. But, alas, I never got the chance to fly it.
As to your question about the propeller:
I cannot give you specific design criteria for the P-47 except to
say, in general,
propeller design is quite heavily a function of:
engine horsepower
required aircraft speed at a particular altitude
maximum allowable propeller diameter
The above criteria force the actual design of the propeller, in terms of:
efficiency at various speeds and altitudes
thrust
pitch
The early P-47 propellers had only (3) blades mounted on a 2,000 HP engine.
They had a top speed of about 400 mph at 27,000 ft. Their rate of climb was
not very good,- only about1650 ft / min. at sea level.
Later designs had an enormous (4) bladed,12 ft. dia. propeller using a 2300 HP
water-injection engine giving a rate of climb about 2700 ft / min. at 5,000 ft.
Final designs retained the (4) bladed prop on a 2800 HP turbocharged engine.
This gave them a top speed of 470 mph at 30,000 ft., with a rate of
climb of 3500
ft / min.
I believe all of the props were of constant-speed design, varying the
pitch auto-
matically. The fighter was designed for high-altitude flight.
You probably know all this and I must apologize if I sound pedantic. I am not
versed on the specifics of the actual numbers that went into the
design of the P-47
prop.
Uri.
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