Return-Path: Sender: (Marvin Kaye) To: lml Date: Sun, 23 Mar 2003 22:59:08 -0500 Message-ID: X-Original-Return-Path: Received: from imo-r04.mx.aol.com ([152.163.225.100] verified) by logan.com (CommuniGate Pro SMTP 4.1b1) with ESMTP id 2083966 for lml@lancaironline.net; Sun, 23 Mar 2003 19:50:11 -0500 Received: from Sky2high@aol.com by imo-r04.mx.aol.com (mail_out_v34.21.) id q.17.37835f02 (3842) for ; Sun, 23 Mar 2003 09:31:23 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <17.37835f02.2baf1f3a@aol.com> X-Original-Date: Sun, 23 Mar 2003 09:31:22 EST Subject: Tip Speed Query X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_17.37835f02.2baf1f3a_boundary" X-Mailer: 8.0 for Windows sub 870 --part1_17.37835f02.2baf1f3a_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Let's say we have an airplane traveling at 200 Kts with a 6 foot diameter (D) prop operating at 2500 rpm. An ordinary calculation would show the tip (per minute) to be Pi x D x rpm or 6 x Pi x 2500 = 47124 ft per min or 535 mph. But, the tip is describing a helix because, at 200 Kts, the plane is moving forward at 1,215,223 feet per hour. The length of the helix path is: Square Root ( (Pi x D)squared + distance squared) (Pi x 6) squared = 355.1 distance of one revolution = 1215223 / 60 = 20253 / 2500 = 8.1 feet per revolution. distance squared = 65.6 And the square root of the sum = SQRT (420.7) = 20.5 feet per revolution or 20.5 x 2500 = 51,250 feet per minute or 51250 x 60 = 3,075,000 feet per hour or 582 mph. Aren't we getting close to Mach 1? What about when we Race at 2700 rpm? What about a IV or a Legacy? Scott Krueger Sky2high@aol.com LNC2 N92EX IO320 Aurora, IL (KARR) --part1_17.37835f02.2baf1f3a_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Let's say we have an airplane traveling at 200 Kts with a 6 foot diameter (D= ) prop operating at 2500 rpm.

An ordinary calculation would show the tip (per minute) to be Pi x D x rpm o= r

6 x Pi x 2500 =3D 47124 ft per min or 535 mph.

But, the tip is describing a helix because, at 200 Kts, the plane is moving=20= forward at 1,215,223 feet per hour. The length of the helix path is:
Square Root ( (Pi x D)squared + distance squared)

(Pi x 6) squared =3D 355.1

distance of one revolution =3D 1215223 / 60 =3D 20253 / 2500 =3D 8.1 feet pe= r revolution.

distance squared =3D 65.6

And the square root of the sum =3D SQRT (420.7) =3D 20.5 feet per revolution= or

20.5 x 2500 =3D 51,250 feet per minute or

51250 x 60 =3D 3,075,000 feet per hour or 582 mph.

Aren't we getting close to Mach 1?

What about when we Race at 2700 rpm?

What about a IV or a Legacy?

Scott Krueger
Sky2high@aol.com
LNC2 N92EX IO320 Aurora, IL (KARR) --part1_17.37835f02.2baf1f3a_boundary--