Return-Path: Received: from fed1rmmtao07.cox.net ([68.230.241.32] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 592084 for flyrotary@lancaironline.net; Wed, 05 Jan 2005 08:52:13 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.32; envelope-from=daveleonard@cox.net Received: from davidandanne ([68.111.224.107]) by fed1rmmtao07.cox.net (InterMail vM.6.01.04.00 201-2131-117-20041022) with SMTP id <20050105135140.JFSP21886.fed1rmmtao07.cox.net@davidandanne> for ; Wed, 5 Jan 2005 08:51:40 -0500 From: "DaveLeonard" To: "Rotary motors in aircraft" Subject: RE: [FlyRotary] IAS and Vne! Whoa! Date: Wed, 5 Jan 2005 05:53:46 -0800 Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_007C_01C4F2EA.EBE0E4F0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) In-Reply-To: X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_007C_01C4F2EA.EBE0E4F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Well that's just great. Makes sense now that you bring it up. Anyone want to buy a turbocharged RV-6? I guess I don't need those 12" numbers after all ;-) Dave Leonard -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Ed Anderson Sent: Tuesday, January 04, 2005 7:56 AM To: Rotary motors in aircraft Subject: [FlyRotary] IAS and Vne! Whoa! In Van's RvAtor mag there is an eye-opening article on Vne (never exceed airspeed). We all (most?) have it marked on our Indicated Airspeed Gauges with the Red Line along with our stall speeds, flap extension limits, turbulent air limits, etc. Well, it appears that all of the other airspeed limits mentioned are a function of the "Q" factor (aerodynamic pressure) as is our Indicated Airspeed. As the relative Q changes with changing airspeed/altitude those limits stay in sync with the indicator. So most of us (I know I did) assumed the Vne on the indicated airspeed is also a function of the "Q" factor. Apparently Vne is NOT, it is a factor of True Airspeed!! Normally this does not mean much, BUT, if you are turbocharging your aircraft and intend to fly at altitudes greater than 10,000 ft (especially with a turbocharged engine which can give you sea level power) it can be very important. The reason is that Indicated airspeed continues to decrease (for a constant true airspeed) as altitude increases(air density decreases). However, in most cases our True airspeed increases somewhat with altitude. Van apparently figures that with a normally aspired engine your power decrease would limit your true airspeed potential to below Vne (at those higher altitudes) - but, if you have the power (turbocharged) to give you a higher airspeed then there could be a potential problem. The bottom line is that at the higher altitudes your indicated airspeed gauge can be showing you safely below the Red Vne mark but, your True Airspeed may be exceeding Vne by a considerably margin putting your airframe in a potentially danger zone of flutter. Just though I would pass it on. The full article is in the latest Rvator and was a response to folks asking about turbocharging the engine for the RV-10 to make it a high speed long range cruiser. The rest of you may have been aware of this difference, but I know I was not. FWIW Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ------=_NextPart_000_007C_01C4F2EA.EBE0E4F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Well=20 that's just great. Makes sense now that you bring it up. = Anyone want=20 to buy a turbocharged RV-6? I guess I don't need those 12" numbers = after=20 all ;-)

Dave=20 Leonard

-----Original Message-----
From: Rotary motors in = aircraft=20 [mailto:flyrotary@lancaironline.net]On Behalf Of Ed=20 Anderson
Sent: Tuesday, January 04, 2005 7:56 = AM
To:=20 Rotary motors in aircraft
Subject: [FlyRotary] IAS and Vne!=20 Whoa!

In Van's RvAtor mag there is an = eye-opening=20 article on Vne (never exceed airspeed). We all (most?) have it = marked on=20 our Indicated Airspeed Gauges with the Red Line along with our stall = speeds,=20 flap extension limits, turbulent air limits, etc.

Well, it appears that all of the = other=20 airspeed limits mentioned are a function of the "Q" factor = (aerodynamic=20 pressure) as is our Indicated Airspeed. As the relative = Q changes=20 with changing airspeed/altitude those limits stay in = sync with the=20 indicator. So most of us (I know I did) assumed the Vne on = the=20 indicated airspeed is also a function of the "Q" factor. = Apparently Vne=20 is NOT, it is a factor of True Airspeed!!

Normally this does not mean much, = BUT, if you are=20 turbocharging your aircraft and intend to fly at altitudes greater = than 10,000=20 ft (especially with a turbocharged engine which can give you sea level = power)=20 it can be very important. The reason is that Indicated airspeed=20 continues to decrease (for a constant true airspeed) as altitude=20 increases(air density decreases). However, in most cases our = True=20 airspeed increases somewhat with altitude. Van=20 apparently figures that with a normally aspired engine your power = decrease would limit your true airspeed potential to below Vne (at = those=20 higher altitudes) - but, if you have the power (turbocharged) to = give=20 you a higher airspeed then there could be a potential = problem.

The bottom line is that at the higher = altitudes=20 your indicated airspeed gauge can be showing you safely below the = Red Vne=20 mark but, your True Airspeed may be exceeding Vne by a considerably = margin=20 putting your airframe in a potentially danger zone of = flutter.

Just though I would pass it on. = The full=20 article is in the latest Rvator and was a response to folks asking = about=20 turbocharging the engine for the RV-10 to make it a high speed long = range=20 cruiser.

The rest of you may have been = aware of this=20 difference, but I know I was not.

FWIW

Ed

Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com

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