X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 02 Jan 2014 12:39:03 -0500 Message-ID: X-Original-Return-Path: Received: from mta31.charter.net ([216.33.127.82] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTP id 6665822 for lml@lancaironline.net; Thu, 02 Jan 2014 11:33:31 -0500 Received-SPF: pass receiver=logan.com; client-ip=216.33.127.82; envelope-from=farnsworth@charter.net Received: from imp10 ([10.20.200.15]) by mta31.charter.net (InterMail vM.8.01.05.02 201-2260-151-103-20110920) with ESMTP id <20140102163255.XMEN24708.mta31.charter.net@imp10> for ; Thu, 2 Jan 2014 11:32:55 -0500 Received: from OWNERPC ([24.240.22.2]) by imp10 with smtp.charter.net id 94Yu1n00s02iJEo054Yu2g; Thu, 02 Jan 2014 11:32:55 -0500 X-Authority-Analysis: v=2.0 cv=brYUnzmi c=1 sm=1 a=mHRM3OX74vzkVKuopJY6mQ==:17 a=KeD-AIHC2KQA:10 a=yUnIBFQkZM0A:10 a=hOpmn2quAAAA:8 a=zWIqIkwttyIA:10 a=Ia-xEzejAAAA:8 a=DZykBHxpgaDeoLXJfuAA:9 a=CjuIK1q_8ugA:10 a=EzXvWhQp4_cA:10 a=yMhMjlubAAAA:8 a=SSmOFEACAAAA:8 a=1KkTn4dCmERWnu_tiJMA:9 a=gKO2Hq4RSVkA:10 a=UiCQ7L4-1S4A:10 a=hTZeC7Yk6K0A:10 a=frz4AuCg-hUA:10 a=ZrOQ2lemCYCRU_hg:21 a=mHRM3OX74vzkVKuopJY6mQ==:117 From: "Lynn Farnsworth" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: RE: [LML] Legacy Takeoff Performance at High Elevation Airports? X-Original-Date: Thu, 2 Jan 2014 11:32:49 -0500 X-Original-Message-ID: <01ad01cf07d8$46f44e20$d4dcea60$@charter.net> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01AE_01CF07AE.5E21C890" X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQJF0U6P7eds4M73bLid0RrUG0EWF5mEBZKg Content-Language: en-us This is a multipart message in MIME format. ------=_NextPart_000_01AE_01CF07AE.5E21C890 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Valin, I have a TSIO-550 powered Legacy. I'm assuming you have a standard IO-550 engine. The compression ratio for my engine is 7.5:1. I think your engine is probably 10:1. If you don't install intercoolers for the turbos the IAT (inlet air temperature) will probably be in the neighborhood of 30 to 40 degrees F above a non turbocharged engine. That being said, I don't think that would be a problem as long as you keep the MP at 30". As far as high density altitude performance is concerned, You will be happy with what a turbocharger can do for you. Though there is slight increase in ground speed/true airspeed for the same indicated airspeed as altitude is increased the turbocharger will allow you to only give the factor little consideration. The engine will produce sea level as long as you maintain 30" of MP. This also allows you to not have to make constant changes to the mixture during the climb. The turbos will certainly reduce the density altitude restraints to only a minor consideration. Just remember the compression ratio and don't start pushing the throttle to where the MP is much above 30". Lynn Farnsworth Super Legacy #235 TSIO-550 Powered From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Valin & Allyson Thorn Sent: Thursday, January 02, 2014 10:19 AM To: lml@lancaironline.net Subject: [LML] Legacy Takeoff Performance at High Elevation Airports? Hey LML gang, With an eye toward practicing instrument approaches, I downloaded the RealAir Lancair Legacy airplane model for Flight Simulator X. I'll send a separate LML post asking about its accuracy to focus that particular discussion. I was impressed, though, with its apparent flight performance fidelity in general. With our Legacy still under construction, it was interesting to fly the simulated Legacy out of our new airport base in Colorado at the Rocky Mountain Metro Airport (KBJC) near Boulder (former Jeffco) with a field elevation of about 5673 ft MSL. Fortunately the longest runway is about 9000 ft long. Even with that, if the Legacy sim model is fairly accurate, it has me concerned about takeoff performance especially during summers with density altitudes as high as around 9000 ft. With a naturally aspirated engine we'll be looking at only about 24" of manifold pressure at full throttle and the thinner air for the prop and wings... So my question is, what kind of takeoff performance are Legacy pilots seeing at high elevation airports - take off rollout, climb rates, etc.? This has us thinking about at least turbo-normalizing our IO-550 engine. For those with turbo-chargers, what kind of improvement in performance are you seeing at high elevation airports? Also, how are pilots adjusting their takeoff technique at high elevations. In comparing the sim Legacy at sea level and in Colorado, and being on the back side of the power curve below about 120 kts, it helps to delay take off rotation speed at high elevation in the sim. Real world.? Thanks, Valin Thorn Legacy Project Boulder, Colorado ------=_NextPart_000_01AE_01CF07AE.5E21C890 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Valin,

 

I have a = TSIO-550 powered Legacy. I’m assuming you have a standard IO-550 = engine. The compression ratio for my engine is 7.5:1. I think your = engine is probably 10:1. If you don’t install intercoolers for the = turbos the IAT (inlet air temperature) will probably be in the = neighborhood of 30 to 40 degrees F above a non turbocharged engine. That = being said, I don’t think that would be a problem as long as you = keep the MP at 30”.

 

As far as = high density altitude performance is concerned, You will be happy with = what a turbocharger can do for you. Though there is slight increase in = ground speed/true airspeed for the same indicated airspeed as altitude = is increased the turbocharger will allow you to only give the factor = little consideration. The engine will produce sea level as long as you = maintain 30” of MP. This also allows you to not have to make = constant changes to the mixture during the = climb.

 

The turbos = will certainly reduce the density altitude restraints to only a minor = consideration. Just remember the compression ratio and don’t start = pushing the throttle to where the MP is much above = 30”.

 

Lynn = Farnsworth

Super Legacy = #235

TSIO-550 = Powered

 

From:= = Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = Valin & Allyson Thorn
Sent: Thursday, January 02, 2014 = 10:19 AM
To: lml@lancaironline.net
Subject: [LML] = Legacy Takeoff Performance at High Elevation = Airports?

 

Hey LML = gang,

 

With an eye toward practicing = instrument approaches, I downloaded the RealAir Lancair Legacy airplane = model for Flight Simulator X.  I’ll send a separate LML post = asking about its accuracy to focus that particular discussion.  I = was impressed, though, with its apparent flight performance fidelity in = general.

 

With our Legacy still under = construction, it was interesting to fly the simulated Legacy out of our = new airport base in Colorado at the Rocky Mountain Metro Airport (KBJC) = near Boulder (former Jeffco) with a field elevation of about 5673 ft = MSL.  Fortunately the longest runway is about 9000 ft long.  = Even with that, if the Legacy sim model is fairly accurate, it has me = concerned about takeoff performance especially during summers with = density altitudes as high as around 9000 ft.  With a naturally = aspirated engine we’ll be looking at only about 24“ of = manifold pressure at full throttle and the thinner air for the prop and = wings...

 

So my question is, what kind of = takeoff performance are Legacy pilots seeing at high elevation airports = – take off rollout, climb rates, etc.?  This has us thinking = about at least turbo-normalizing our IO-550 engine…  For = those with turbo-chargers, what kind of improvement in performance are = you seeing at high elevation airports?

 

Also, how are pilots adjusting their = takeoff technique at high elevations.  In comparing the sim Legacy = at sea level and in Colorado, and being on the back side of the power = curve below about 120 kts, it helps to delay take off rotation speed at = high elevation in the sim.  Real world…?  =

 

Thanks,

 

Valin Thorn

Legacy = Project

Boulder, = Colorado

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