X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 50 [XX] Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 12 May 2007 22:57:54 -0400 Message-ID: X-Original-Return-Path: Received: from vms042pub.verizon.net ([206.46.252.42] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2040486 for lml@lancaironline.net; Sat, 12 May 2007 20:44:53 -0400 Received: from [192.168.111.2] ([70.19.63.246]) by vms042.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0JHY00988FEFPB89@vms042.mailsrvcs.net> for lml@lancaironline.net; Sat, 12 May 2007 19:44:41 -0500 (CDT) X-Original-Date: Sat, 12 May 2007 20:44:33 -0400 From: Kevin Kossi Subject: Re: [LML] Re: IO-550 fuel injection In-reply-to: X-Original-To: "Lancair Mailing List" X-Original-Message-id: <3CDB07F2-DED2-42F8-9A7E-6656E3A9791C@airforcemechanical.com> MIME-version: 1.0 (Apple Message framework v752.2) X-Mailer: Apple Mail (2.752.2) Content-type: multipart/alternative; boundary=Apple-Mail-107-993894049 References: --Apple-Mail-107-993894049 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed OK, lets have some fun with numbers: I would think the volume of air flowing through the ram air vacuum breaker tube would be equal to the volume of fuel being drawn from the tank. To figure out the speed at which the make-up air is flowing through that tube: Provided you are drawing from one tank at a time: If the engine is using 15 Gallon per hour, at 231 Cu/In per gallon, thats 3,465 Cu/In per hour, divided by 1728 to get Cubic Feet Per Minute, which it 2.00520833 Cubic Feet Per Hour Divide by 60 to get Cubic Feet Per Minute, that's .03342014 CFM (I need to convert tot CFM because my air velocity calculator only works in CFM) I put the following into my air velocity calculator: Tube inside diameter: 0.139 Tube Length: .75' CFM: .03342014 I get the following: Velocity: 317.14 FPM - Feet per minute Friction loss: 0.068985 " WC Reynolds #: 383.33 Now if I I use 5,280' in a mile and divide that by 60 to get Feet per minute, I get 88 FPM for one mile an hour, divide our 317.14 FPM velocity by 88, we get 3.6 Miles per hour. I would think under the right conditions that might be enough velocity to suck some water up the tube. If you want to work the number through there is an online air velocity calculator you can use to figure different tube sizes and lengths: http://efficientcomfort.net/jsp/DuctCalculator_Web.jsp Kevin Kossi Legacy 80% New York Continental IO-550-EXP 10:1 Single Lightspeed Single Slick Mag Hartzell HC-H3YF-2UFX/FC7391D-3X. Full feathering, counterweighted, 3 blade On May 12, 2007, at 12:28 PM, glong2 wrote: > Rick, Mike > > I have looked at all common components and cannot find an air leak > or loose > fitting anywhere. If it is intermittent I don't know how to > troubleshoot, > but it has not happened again! > > My son came up with a possibility that has a high probability of > causing the > problem. The only hang-up is that it happened on both vent lines; > that seems > to lower the probability. > > Here is the theory. The 1/4" tube from the NACA scoop takes a > 180 degree > 1" uphill bend. The flex tube from the NACA scoop to the tank vent > line then > goes uphill another 1" to the fuel tank vent line. The 1/4" vent > line goes > downhill to the tank by the camber of the wing. The PROBLEM: a 1" > uphill > metal tube, a 1/2" downhill flex tube then 1.5" uphill to the tank > vent > line. Think of a "P" trap under your sink. > > I took the wing tips off and sure enough that is exactly what I > had. Because > I built everything symmetrical, both wing vents were the same. Not > only > that, there was clear evidence that there had been something in the > P trap > at some time because the flex tubing was discolored in the low > spot. It was > very evident in the right wing and not so evident in the left wing. I > naturally fixed the problem by replacing the tubing with a length > 1" longer > than 1/2 of the old length. > > How did water get into the P trap? As I said, it is the only time I > squeeged the wings parallel to the cord. There was enough moisture > that it > was running down the wings in places. (I need to do the experiment of > drizzling water down the edge of the wingtip to see if it collects > in the > NACA scoop.) If there was water in the scoop, then it could have > been sucked > into the trap from start-up prop wash, taxing, or on takeoff. > > Why both tanks? My standard starting procedure is to prime and > start on > the left tank and run on it until the Chelton system boots up. Then > I switch > to the right tank for taxi, run-up and takeoff. No boost pump until > takeoff. > > > Soooo-- > > It is possible for both the left and right traps to get water in > them from > prop wash or taxi and maybe at takeoff. The boost pump would suck hard > enough to overcome the small amount of water in the trap, but it > did not > suck it into the tank. Since there was a small vacuum in the tank, > when I > shut off the boost pump the fuel flow and pressure would > immediately go to > zero and the engine quit. This assumes that the mechanical fuel > pump could > not overcome about 1/2" to 1" water pressure. Before I landed the > water had > evaporated and on the ground and ever since I could not/cannot > repeat the > problem. > > The best reasonable explanation I have come up with! > > Yes, I was running LOP as I always do. I have more time than money. I > usually run 12.5 with no wind and 13 to 13.5 against the wind. I > tested the > vent lines and neither had a restriction except for the 1/4" > diameter. No I > have not drained the gas filter because I hoped to repeat the > problem. Now > that I have a "high probability" solution I will sump the filter. > > > Eugene Long > Lancair Super ES > glong2@netzero.net > --Apple-Mail-107-993894049 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1
OK, lets have = some fun with numbers:

I would think = the volume of air flowing through the ram air vacuum breaker tube would = be equal to the volume of fuel being drawn from the tank.

To figure out the speed at which the make-up air is = flowing=A0through that tube:

Provided you = are drawing from one tank at a time:
If the engine = is using 15 Gallon per hour, at 231 Cu/In per gallon, thats 3,465 Cu/In = per hour,=A0divided by 1728 to get Cubic Feet Per Minute, which it = 2.00520833 Cubic Feet Per Hour
Divide=A0by 60 to get = Cubic Feet Per Minute, that's .03342014 CFM

(I need to=A0convert=A0tot = CFM because my air velocity calculator only works in CFM)

I put the following into my = air velocity calculator:
Tube inside diameter: = 0.139
Tube Length: .75'
CFM:=A0.03342014
I get the = following:=A0
Velocity: 317.14 FPM - Feet = per=A0minute
Friction loss: 0.068985 " WC
Reynolds = #: 383.33

Now = if I I use 5,280' in a mile and=A0divide that by 60 to get Feet per = minute, I get 88 FPM for one mile an hour,=A0divide our 317.14 FPM = velocity by 88, we get 3.6 Miles per hour.

I would think under the = right=A0conditions that might be=A0enough velocity to suck some water up = the tube.

If = you want to work the number through there is an online air velocity = calculator you can use to figure=A0different tube sizes and lengths:=A0http://eff= icientcomfort.net/jsp/DuctCalculator_Web.jsp




Kevin = Kossi
Legacy 80%
New York=A0
Continental = IO-550-EXP
10:1=A0Single Lightspeed=A0Single Slick = Mag
Hartzell=A0 = HC-H3YF-2UFX/FC7391D-3X.
Full feathering, counterweighted, 3 = blade=A0

On May 12, 2007, at 12:28 = PM, glong2 wrote:

Rick, Mike

I have = looked at all common components and cannot find an air leak or = loose
fitting anywhere. If it is = intermittent I don't know how to troubleshoot,
but it has not happened again!

My son = came up with a possibility that has a high probability of causing = the
problem. The only hang-up is = that it happened on both vent lines; that seems
to lower the probability.

Here is = the theory. =A0 =A0 The = 1/4" tube from the NACA scoop takes a 180 degree
1" uphill bend. The flex tube from the NACA scoop to = the tank vent line then
goes uphill = another 1" to the fuel tank vent line. The 1/4" vent line goes
downhill to the tank by the camber of the wing.=A0 The PROBLEM:=A0 a 1" uphill
metal tube, a 1/2" downhill flex tube then 1.5" = uphill to the tank vent
line. Think = of a "P" trap under your sink.=A0

I took the = wing tips off and sure enough that is exactly what I had. = Because
I built everything symmetrical, = both wing vents were the same. Not only
that, = there was clear evidence that there had been something in the P = trap
at some time because the flex = tubing was discolored in the low spot. It was
very evident in the right wing and not so evident in = the left wing. I
naturally fixed the problem by = replacing the tubing with a length 1" longer
than 1/2 of the old length.

How did = water get into the P trap?=A0 =A0 = As I said, it is the only time I
squeeged = the wings parallel to the cord. There was enough moisture that = it
was running down the wings in places. (I need = to do the experiment of
drizzling = water down the edge of the wingtip to see if it collects in = the
NACA scoop.) If there was water = in the scoop, then it could have been sucked
into the trap from start-up prop wash, taxing, or on = takeoff.=A0

Why both = tanks?=A0 =A0 My standard = starting procedure is to prime and start on
the = left tank and run on it until the Chelton system boots up. Then I = switch
to the right tank for taxi, = run-up and takeoff. No boost pump until takeoff.



It is possible for both the left and right traps to = get water in them from
prop wash or taxi and maybe = at takeoff. The boost pump would suck hard
enough = to overcome the small amount of water in the trap, but it did = not
suck it into the tank. Since = there was a small vacuum in the tank, when I
shut off the boost pump the fuel flow and pressure = would immediately go to
zero and the = engine quit. This assumes that the mechanical fuel pump could
not overcome about 1/2" to 1" water pressure. Before = I landed the water had
evaporated and on the = ground and ever since I could not/cannot repeat the
problem.

The best reasonable explanation = I have come up with!=A0

Yes, I was = running LOP as I always do. I have more time than money. I
usually run 12.5 with no wind and 13 to 13.5 against = the wind. I tested the
vent lines and neither had = a restriction except for the 1/4" diameter. No I
have not drained the gas filter because I hoped to = repeat the problem. Now
that I have a = "high probability" solution I will sump the filter.


Eugene = Long
Lancair Super ES




= --Apple-Mail-107-993894049--