X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 27 Dec 2011 09:36:17 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-kukur.atl.sa.earthlink.net ([209.86.89.65] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with ESMTP id 5327937 for lml@lancaironline.net; Tue, 27 Dec 2011 09:27:12 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.65; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=iZLTrHJP+JCCKeOrcs44CKNfs5oC6RjT6zya+47kWJmyjfEiz40fgNh8ntujqXY7; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [72.73.82.58] (helo=[192.168.1.24]) by elasmtp-kukur.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1RfXz6-0000eP-9i for lml@lancaironline.net; Tue, 27 Dec 2011 09:26:32 -0500 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-896-943924336 Subject: Re: [LML] Re: Performance specs X-Original-Date: Tue, 27 Dec 2011 09:26:31 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <3F37A69D-732A-4940-A775-2B7F33804B09@earthlink.net> X-Mailer: Apple Mail (2.1084) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da9405223508497d98c5ae656722722ecf2e9350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 72.73.82.58 --Apple-Mail-896-943924336 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Gary, interesting chart. How would it have to be modified for a IVP? Colyn On Dec 27, 2011, at 12:51 AM, Gary Casey wrote: Jim, Attached is a spreadsheet that I developed for my (naturally aspirated) = ES. It calculates takeoff roll from the basic forces - rolling = resistance, propeller thrust, efficiency, etc. and it computes the = effect of altitude separately on engine power and takeoff speed. It can = compensate for altitude, temperature and runway slope, but not humidity. = You can change the values in the green cells to match existing = conditions. The values in the white cells are the fundamental factors = used in the calculations. The blue cells are calculated intermdediate = results. The graph shows distance vs the "speed remaining" before = liftoff, so when it goes to zero it is liftoff time. I have checked the = results for takeoff distance from sea level to 10,000 ft. density = altitude and it matches the actual takeoff very closely. =20 My takeoff procedure is to select about 15 degrees of flap (I don't see = much difference from 10 to 20 degrees) and full throttle. Elevations = above 5,000 include leaning to pea power. At 60 knots I lift the = nosewheel off and wait until it flies off. If I get anxious I can get a = brief AOA warning, so I don't get too aggressive. It flies off at = probably 80 knots. Like you, I don't see much point in pulling it off = early, only to wait in ground effect for it to pick up climb speed. So = the calculations are for the distance required to get to a speed that = actually allows a reasonable climb rate. =20 With the numbers shown in the spreadsheet you can see that the predicted = takeoff distance is about 1400 ft, longer than the advertising = literature would have you believe. I think the ditances calculated are = best described as a "reasonable, conservative" prediction of = performance. =46rom Jim: Guys, I am trying to tweak my Super ES performance information and would like = your input on a couple of things. I want to put together some charts/tables that let me calculate my = plane's performance relative to density altitude. The purpose of this = information gathering exercise is to put together a chart that can use = realistic numbers to help me calculate performance at higher elevations = and density altitudes. I want to do some flying out west and feel my = tools are lacking where performance calculations for my plane are = concerned. My gray area is take-off distance. I have never actually done my own = tests in this area other than paying attention at my home airport about = where down the runway I start flying. If any of you have actual numbers = for your ES I would like to see them if you don't mind. Consensus of information that I found on the internet and in Lancair = publications seems to be about a 700 ft ground roll on a standard day at = sea level for 3400 pound gw. This number appears unrealistic to me.=20 The standard procedure that I have seen in a couple of places seems to = require lifting the nose wheel around 55 and climbing at 85. Doesn't = mention holding brakes till full power. Can't seem to find information = that indicates when this method causes the plane to break ground. (Might = be the 700 feet that is mentioned). This strikes me as an aggressive = method (might not be, just seems so to me given my experience in my = plane). I am not a test pilot and have no intention of flying at what = might be the edge of the envelope. I prefer a bit of a conservative = number, whatever it might be. I have tried this method on a few occasions and I find it somewhat = uncomfortable because the plane tends to settle in a tail low attitude = after becoming airborne and seems quite lazy even while still in ground = effect. I prefer crisp performance and firm response to control inputs. = The 55/85 process doesn't seem to fit these preferences. My method involves 10 degrees of flaps, deliberate, but not speedy, = application of power, slight back pressure on stick beginning about 65, = holding that pressure until plane flies off. Usually flying occurs at = about 85-90 with no "sag" feeling and very positive control response. = Climb out is at 100 till 400 feet then 125-130 to altitude. =20 On an approximately standard day this results in wheels off the runway = at about 900 feet at about 3200 pounds. At gross of 3400 the number is = about 1100. Again I have done no actual measurements, just judging by = the thousand foot marks on the runway. =20 So is it possible to put together a chart that can help me figure ground = roll and climb rate for various gross weight situations? Is one already = available that I just don't know about? The Koch Chart only requires = ground roll and climb rate for performance calculations relative to = density altitude. =20 I appreciate any input you might have on this subject. I have not seen = this subject on LML so maybe I am not the only one who could use this = information. Just trying to be safe. Thanks, Jim Scales (almost 1200 hours and very happy) -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html --Apple-Mail-896-943924336 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii
Jim,
Attached is = a spreadsheet that I developed for my (naturally aspirated) ES.  It = calculates takeoff roll from the basic forces - rolling resistance, = propeller thrust, efficiency, etc. and it computes the effect of = altitude separately on engine power and takeoff speed.  It can = compensate for altitude, temperature and runway slope, but not = humidity.  You can change the values in the green cells to match = existing conditions.  The values in the white cells are the = fundamental factors used in the calculations.  The blue cells are = calculated intermdediate results.  The graph shows distance vs the = "speed remaining" before liftoff, so when it goes to zero it is liftoff = time.  I have checked the results for takeoff distance from sea = level to 10,000 ft. density altitude and it matches the actual takeoff very = closely.
 
My takeoff = procedure is to select about 15 degrees of flap (I don't see much = difference from 10 to 20 degrees) and full throttle.  Elevations = above 5,000 include leaning to pea power.  At 60 knots I lift the = nosewheel off and wait until it flies off.  If I get anxious I can = get a brief AOA warning, so I don't get too aggressive.  It flies = off at probably 80 knots.  Like you, I don't see much point in = pulling it off early, only to wait in ground effect for it to pick up = climb speed.  So the calculations are for the distance required to = get to a speed that actually allows a reasonable climb = rate.
 
With the = numbers shown in the spreadsheet you can see that the predicted takeoff = distance is about 1400 ft, longer than the advertising literature would = have you believe.  I think the ditances calculated are best described as a = "reasonable, conservative" prediction of = performance.

=20 =20 =46rom Jim:
Guys,
I am trying to tweak my = Super ES performance information and would like your input on a couple = of things.

I want to put together some = charts/tables that let me calculate my plane's performance relative to = density altitude. The purpose of this information gathering = exercise is to put together a chart that can use realistic numbers to = help me calculate performance at higher elevations and density = altitudes.  I want to do some flying out west and feel my tools are = lacking where performance calculations for my plane are = concerned.

My = gray area is take-off distance.  I have never actually done my own = tests in this area other than paying attention at my home airport about = where down the runway I start flying. If any of you have actual numbers = for your ES I would like to see them if you don't mind.

Consensus of information that I found on the internet = and in Lancair publications seems to be about a 700 ft ground roll on a = standard day at sea level for 3400 pound gw.  This number appears = unrealistic to me. 

The standard = procedure that I have seen in a couple of places seems to require = lifting the nose wheel around 55 and climbing at 85.  Doesn't = mention holding brakes till full power.  Can't seem to find = information that indicates when this method causes the plane to break = ground. (Might be the 700 feet that is mentioned). This strikes me = as an aggressive method (might not be, just seems so to me given my = experience in my plane).  I am not a test pilot and have no = intention of flying at what might be the edge of the envelope.  I = prefer a bit of a conservative number, whatever it might be.

I have tried this method on a few occasions and I find = it somewhat uncomfortable because the plane tends to settle in a tail low = attitude after becoming airborne and seems quite lazy even while still = in ground effect.  I prefer crisp performance and firm response to = control inputs. The 55/85 process doesn't seem to fit these = preferences.

My method involves 10 degrees of = flaps, deliberate, but not speedy, application of power, slight back = pressure on stick beginning about 65, holding that pressure until plane = flies off.  Usually flying occurs at about 85-90 with no "sag" = feeling and very positive control response. Climb out is at 100 till 400 = feet then 125-130 to altitude.  

On an approximately standard day this results in wheels off = the runway at about 900 feet at about 3200 pounds.  At gross of = 3400 the number is about 1100.  Again I have done no actual = measurements, just judging by the thousand foot marks on the runway.
 
So is it = possible to put together a chart that can help me figure ground roll and = climb rate for various gross weight situations?  Is one already = available that I just don't know about?  The Koch Chart only = requires ground roll and climb rate for performance calculations = relative to density altitude.
 
I appreciate any input you might have on this subject. =  I have not seen this subject on LML so maybe I am not the only one = who could use this information.

Just trying to be safe.

Thanks,

Jim = Scales  (almost 1200 hours and very happy)



=


<Takeoff = Performance2.xlsx>--
For archives and unsub http://mail.= lancaironline.net:81/lists/lml/List.html

= --Apple-Mail-896-943924336--