X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imf24aec.mail.bellsouth.net ([205.152.59.72] verified) by logan.com (CommuniGate Pro SMTP 5.0.4) with ESMTP id 889257 for flyrotary@lancaironline.net; Mon, 19 Dec 2005 21:37:46 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.72; envelope-from=atlasyts@bellsouth.net Received: from ibm68aec.bellsouth.net ([65.2.250.50]) by imf24aec.mail.bellsouth.net with ESMTP id <20051220023611.IOWL9737.imf24aec.mail.bellsouth.net@ibm68aec.bellsouth.net> for ; Mon, 19 Dec 2005 21:36:11 -0500 Received: from [192.168.0.100] (really [65.2.250.50]) by ibm68aec.bellsouth.net with ESMTP id <20051220023609.CAYQ28650.ibm68aec.bellsouth.net@[192.168.0.100]> for ; Mon, 19 Dec 2005 21:36:09 -0500 Mime-Version: 1.0 (Apple Message framework v746.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-13--27285289 Message-Id: <6DF24CAC-079A-4A89-A9A9-2256670C64D5@bellsouth.net> From: Bulent Aliev Subject: Re: [FlyRotary] Re: Props Date: Mon, 19 Dec 2005 21:37:00 -0500 To: "Rotary motors in aircraft" X-Mailer: Apple Mail (2.746.2) --Apple-Mail-13--27285289 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed I used the prop RPM ED? Anyway, as long as I was wring it's OK :) Thanks Ed. Buly On Dec 19, 2005, at 8:25 PM, Ed Anderson wrote: > Bully, the formula's correct. However, you must put in the rpm of > the prop - not the engine which in our case means we need to > simply divide whatever answer you got with the formula by 2.17 > > I get 772 ft/sec for a 64" dia prop with engine turning at 6000 rpm > with a 2.17 > > So formula for us should be tip speed = (Dia" *3.1416* rpm/(12*60))/ > 2.17 or whatever your gear ratio is. > > Ed > ----- Original Message ----- > From: Bulent Aliev > To: Rotary motors in aircraft > Sent: Monday, December 19, 2005 6:44 PM > Subject: [FlyRotary] Re: Props > > Thanks Dave. it makes me feel better now that I know I was wrong. > My problem now is: I can spin my "monster prop" (static) up-to > 4000RPM and 50" MP I don't think I can get much more in motion and > may not get enough rpm for flight. I'll see first how much > difference it will make on fast taxi. John Slade also will bring > his Performance prop one day, so we can compare them. > BTW the prop tip speed formula given to me was: > Prop D" x 3.1416 x RPM divided by 720 > Buly > > On Dec 19, 2005, at 6:06 PM, David Leonard wrote: > >> Oh, BTW Bully. You will also note that at 6000 RPM the prop is >> doing 2750 which a lot of certified props will turn, even if 74"long. >> >> Also, short prop are not necessarily less efficient, its just that >> the speed of peak efficiency is shifted to a higher airspeed, and >> probably that peak is a little more narrow. >> >> Dave Leonard >> >> >> On 12/19/05, Buly wrote: >> Yesterday somebody gave me the formulas to calculate the prop tip >> speed. I did some calculations and looks like us with the 2.17 >> redrives are kind of painted in the corner. Hope I'm wrong, but if I >> want to keep the tips from going supersonic, I have to cut down the >> prop to 64" or keep the engine below 5500 RPM. The choice is either >> inefficient prop and adequate power, or efficient long prop and not >> getting all the power from the engine? Am I wrong? >> Buly >> atlasyts@bellsouth.net >> >> >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >> >> >> >> -- >> Dave Leonard >> Turbo Rotary RV-6 N4VY >> http://members.aol.com/_ht_a/rotaryroster/index.html >> http://members.aol.com/_ht_a/vp4skydoc/index.html > > Bulent Aliev > atlasyts@bellsouth.net > http://home.bellsouth.net/p/s/community.dll? > ep=16&ext=1&groupid=164323&ck= > > > --Apple-Mail-13--27285289 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 I used the prop RPM ED? Anyway, = as long as I was wring it's OK :)
Thanks = Ed.
Buly
On Dec 19, 2005, at 8:25 PM, Ed Anderson = wrote:

Bully, the formula's correct.=A0 However, you must put in the = rpm of the prop -=A0not the engine which in our case means we need to=A0 = simply divide whatever answer you got with the formula by = 2.17
=A0
I get 772 ft/sec for a 64" dia prop with engine turning at 6000 = rpm with a 2.17
=A0
So formula for = us should be tip speed =3D (Dia" *3.1416* rpm/(12*60))/2.17 or whatever = your gear ratio is.
=A0
----- Original = Message -----
Sent: Monday, December 19, 2005 6:44 PM
Subject: [FlyRotary] Re: Props

Thanks = Dave. it makes me feel better now that I know I was wrong. My problem = now is: I can spin my "monster prop" (static) up-to 4000RPM and 50" MP I = don't think I can get much more in motion and may not get enough rpm for = flight. I'll see first how much difference it will make on fast taxi. = John Slade also will bring his Performance prop one day, so we can = compare them.
BTW the prop tip speed formula given to me = was:
Prop D" x 3.1416 x RPM divided by = 720
Buly

On Dec 19, 2005, at 6:06 = PM, David Leonard wrote:

Oh, BTW Bully.=A0 You will also note = that at 6000 RPM the prop is doing 2750 which a lot of certified props = will turn, even if 74"long.
Also, short = prop are not necessarily less efficient, its just that the speed of peak = efficiency is shifted to a higher airspeed, and probably that peak is a = little more narrow.
Dave = Leonard

=A0



-- =
Dave = Leonard
Turbo = Rotary RV-6 N4VY
Bulent Aliev





= --Apple-Mail-13--27285289--