X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 11 Jun 2012 13:08:50 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-masked.atl.sa.earthlink.net ([209.86.89.68] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTP id 5592851 for lml@lancaironline.net; Mon, 11 Jun 2012 10:40:04 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.68; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=fX/G5qbuzhrowzCAcT8JTdzWUvqCysD3+BkTk/uz/iVvQdaF0or5FdT0Z7yKzqt5; 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 [64.222.158.138] (helo=[192.168.1.24]) by elasmtp-masked.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1Se5mC-0006YU-2a for lml@lancaironline.net; Mon, 11 Jun 2012 10:39:28 -0400 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-102-341115008 Subject: Re: [LML] Re: Power loss during descent X-Original-Date: Mon, 11 Jun 2012 10:39:27 -0400 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1084) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da9403d346b8139c1746faa690bb72fe01b80350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 64.222.158.138 --Apple-Mail-102-341115008 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 "...very high descent rates with not much fuel in the selected tank, = lots of air. Could be that tank vents didnt keep up? Low air press in = tank temp impeded flow? A IVP guy reported that he had to modify his = andair vent check valves to allow higher backflow during rapid = descents." just to clarify, I reported modifying my check valves but it was not = for descent. It was for ascent when the hi pressure air in the tank = needs to get out to keep from blowing the wing apart. In a descent you = would have inward flow of the higher pressure air. =20 On Jun 11, 2012, at 9:10 AM, Adam Molny wrote: Thanks for all the quick responses. Here=92s what I have so far: =20 ...very high descent rates with not much fuel in the selected tank, lots = of air. Could be that tank vents didnt keep up? Low air press in tank = temp impeded flow? A IVP guy reported that he had to modify his andair = vent check valves to allow higher backflow during rapid descents. I distinctly recall blowing in both directions through the Andair check = valves before installation. They behaved as expected =96 no restriction = for air entering the tank and some restriction for air leaving the tank. = I looked at the descent rate from my flight data. The vertical speed was = around 1000fpm, which doesn=92t seem excessive. =20 Bob Pastusek pointed me to his article in the LOBO newsletter about = Lancair fuel systems. I have to confess I performed some of the steps in = his articles but not all. The fuel bays in the Legacy wing are = pre-built. I verified that all the inter-bay passages were clear (both = top and bottom) and the flapper doors were working both before and after = wing closing. I sloshed the wing tanks before installation. A tiny = amount of debris and a few bug bodies came out but the fuel samples have = been immaculate since then. My DAR required that I perform the = high-angle-of-attack fuel flow test, and both tanks provided fuel with = the tail resting on the ground and less than 5 gallons per side. =20 Bob also pointed out that prolonged uncoordinated flight will cause fuel = to flow outboard and away from the fuel pickup. I added lateral g=92s to = my graph and bingo! You can clearly see a lateral acceleration during = the descent. We=92re all used to adding right rudder for takeoff and = climb, but I had forgotten that most planes need left rudder during = descent. This is perfectly normal. The canted motor mount that = compensates for left turning tendency works against us during descent so = adding left rudder is to be expected. I just have to remember to step on = the ball both on the way up and the way down! =20 =46rom Scott Kreuger: During the build when it is easy, almost everyone = fails to test "usable fuel" quantities in wing-main-tank systems. That = is, the wing can be tilted up and down in pitch whilst measuring how = much fuel it takes to keep the pickup covered. It seems that usable = fuel in a nose down pitch is wing capacity less 10 or more gallons in = each wing. Hard to tell what the pitch reading means - was that merely = down by 5 or 6 degrees? - only for 2 minutes? The high fuel reading = meant the fuel had gone up higher on the probe - was this an = uncoordinated descent? Where did the left wing fuel hide during the = pitch over or was that in a steep bank? Sorry, the pitch scale is degrees/5 so the maximum descent angle was = 12deg nose down. I had never heard of testing unusable fuel before wing = closing. It certainly would have given some good insight into how the = pickups behave at various flight angles. The fuel probe is a 6=92 metal = tube with an open end and some holes drilled around the base so fuel can = flow in and out. The fuel probes angle up diagonally from wing root to = tip. I suppose if all my fuel ran to the outboard end of the left wing = and the inboard end of the right wing that could explain the fuel level = readings. =20 This was only my second flight with the Dynon so I=92m still tweaking = it. You can bet I=92ll configure that low fuel pressure alarm before my = next flight! =20 -Adam Molny From: Robert R Pastusek [mailto:rpastusek@htii.com]=20 Sent: Friday, June 08, 2012 11:07 PM To: Adam Molny Subject: FW: [LML] Power loss during descent =20 Adam, =20 If you didn=92t correct the asymmetry of the vertical fin, as shipped in = the kit from Lancair, it=92s more likely you unported the fuel pickup = because the aircraft was flying in a skid (the ball not centered). Most = Lancairs have a fin that generates considerably more lift on one side = than the other, resulting in the airplane=92s yaw trim changing = dramatically with changes in both power setting and speed. This, = combined with the very small amount of dihedral in Lancair wings will = unport the fuel pickup easily with large changes in speed until you get = used to harmonizing the rudder. This would be my first guess as to your = problem. =20 I=92d also recommend you set alarms on low fuel pressure and low fuel = flow. These, and other alarms, are really life and equipment safety = precautions. Play with the settings until you get a reliable warning of = trouble without them being a blithering nuisance=85it takes a while. =20 Bob =20 -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html --Apple-Mail-102-341115008 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 "...very high = descent rates with not much fuel in the selected tank, lots of air. = Could be that tank vents didnt keep up?  Low air press in tank temp = impeded flow? A IVP guy reported that he had to modify his andair vent = check valves to allow higher backflow during rapid = descents."

just to clarify,   I reported = modifying my check valves but it was not for descent.  It was for = ascent when the hi pressure air in the tank needs to get out to keep = from blowing the wing apart.  In a descent you would have inward = flow of the higher pressure air.  

On Jun 11, 2012, at 9:10 AM, = Adam Molny wrote:

Thanks for all the quick responses. Here=92s what I have = so far:
...very high descent rates with not much fuel in the = selected tank, lots of air. Could be that tank vents didnt keep = up?  Low air press in tank temp impeded flow? A IVP guy reported = that he had to modify his andair vent check valves to allow higher = backflow during rapid descents.
I = distinctly recall blowing in both directions through the Andair check = valves before installation. They behaved as expected =96 no restriction = for air entering the tank and some restriction for air leaving the tank. = I looked at the descent rate from my flight data. The vertical speed was = around 1000fpm, which doesn=92t seem = excessive.
Bob Pastusek pointed me to his = article in the LOBO newsletter about Lancair fuel systems. I have to = confess I performed some of the steps in his articles but not all. The = fuel bays in the Legacy wing are pre-built. I verified that all the = inter-bay passages were clear (both top and bottom) and the flapper = doors were working both before and after wing closing. I sloshed the = wing tanks before installation. A tiny amount of debris and a few bug = bodies came out but the fuel samples have been immaculate since then. My = DAR required that I perform the high-angle-of-attack fuel flow test, and = both tanks provided fuel with the tail resting on the ground and less = than 5 gallons per side.
Bob also pointed out that prolonged = uncoordinated flight will cause fuel to flow outboard and away from the = fuel pickup. I added lateral g=92s to my graph and bingo! You can = clearly see a lateral acceleration during the descent. We=92re all used = to adding right rudder for takeoff and climb, but I had forgotten that = most planes need left rudder during descent. This is perfectly normal. = The canted motor mount that compensates for left turning tendency works = against us during descent so adding left rudder is to be expected. I = just have to remember to step on the ball both on the way up and the way = down!
=46rom Scott Kreuger: During the = build when it is easy, almost everyone fails to test "usable fuel" = quantities in wing-main-tank systems.  That is, the wing can be = tilted up and down in pitch whilst measuring how much fuel it takes = to keep the pickup covered.  It seems that usable fuel in a nose = down pitch is wing capacity less 10 or more gallons in each = wing.  Hard to tell what the pitch reading means - was that merely = down by 5 or 6 degrees? - only for 2 minutes?  The high fuel = reading meant the fuel had gone up higher on the probe - was this an = uncoordinated descent?  Where did the left wing fuel hide during = the pitch over or was that in a steep = bank?
Sorry, the pitch scale is degrees/5 = so the maximum descent angle was 12deg nose down. I had never heard of = testing unusable fuel before wing closing. It certainly would have given = some good insight into how the pickups behave at various flight angles. = The fuel probe is a 6=92 metal tube with an open end and some holes = drilled around the base so fuel can flow in and out. The fuel probes = angle up diagonally from wing root to tip. I suppose if all my fuel ran = to the outboard end of the left wing and the inboard end of the right = wing that could explain the fuel level readings.This was only my second flight with = the Dynon so I=92m still tweaking it. You can bet I=92ll configure that = low fuel pressure alarm before my next = flight!
-Adam Molny
 Robert R Pastusek = [mailto:rpastusek@htii.com] 
Sent: Friday, June 08, 2012 11:07 = PM
To: Adam Molny
Subject: FW: [LML] Power loss during = descent
If you didn=92t correct = the asymmetry of the vertical fin, as shipped in the kit from Lancair, = it=92s more likely you unported the fuel pickup because the aircraft was = flying in a skid (the ball not centered). Most Lancairs have a fin that = generates considerably more lift on one side than the other, resulting = in the airplane=92s yaw trim changing dramatically with changes in both = power setting and speed. This, combined with the very small amount of = dihedral in Lancair wings will unport the fuel pickup easily with large = changes in speed until you get used to harmonizing the rudder.  = This would be my first guess as to your = problem.
I=92d also recommend = you set alarms on low fuel pressure and low fuel flow. These, and other = alarms, are really life and equipment safety precautions. Play with the = settings until you get a reliable warning of trouble without them being = a blithering nuisance=85it takes a = while.