X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 50 [XX] Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 11 May 2007 21:49:50 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m24.mx.aol.com ([64.12.137.5] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2038898 for lml@lancaironline.net; Fri, 11 May 2007 20:43:00 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.5; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m24.mx.aol.com (mail_out_v38_r9.2.) id q.d06.f5b526b (29678) for ; Fri, 11 May 2007 20:42:13 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Fri, 11 May 2007 20:42:13 EDT Subject: Re: [LML] Re: IO-550 fuel injection, Possible Fuel Vent Clogging Problem X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1178930533" X-Mailer: 9.0 Security Edition for Windows sub 5365 X-Spam-Flag: NO -------------------------------1178930533 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Yep, the table reflects the pressure that a pitot tube would see and could be used for calibration (maybe) of such a tube. Think of it as the maximum pressure that could be pitotically (invented word) obtained if there is no bleed off of the pressure by some sort of leak - like consuming the fuel in the tank. 1/2 the pressure sounds good for a vertical tube with a 45 degree forward facing cut with the aforementioned leak. Maybe it is less for a NACA duct. It is preferable to have a slight positive pressure in a fuel tank provided by the vent. Uh, after all that, does this force water into the tank? If the flow thru a NACA is backed up because it is impeded by back pressure, does water enter the duct at all? Is there yarn small enough, yet big enough to see, that could tell us the flow of water droplets about a teeny NACA? I have further questions, but my wife wants to go to dinner. Tata for now.. Grayhawk In a message dated 5/11/2007 7:16:36 P.M. Central Daylight Time, kyrilian_av@yahoo.com writes: This table looks like simple dynamic pressure. The third report referenced in Chris Z's post (_NACA RM A50E02_ (http://www.n91cz.com/Interesting_Technical_Reports/NACA_inlet_efficiency.pdf) ) provides pressure recovery ratios for various mass flow ratios (discussion on p 5, plots on pages 14-20). While it appears nothing was tested to ratios around zero (1/4 dia wing tank vent lines at 15gph and 200 kts are in the 0.005 range--essentially zero), extrapolating a bunch makes me think we should expect mass flow ratios of 0.5 to 0.8. This is based on -2 to +2deg angle of attack at 0.3 Mach. So divide in half the pressures in the table below for a (maybe) conservative estimate. - Kyrilian Sky2high@aol.com wrote: Mike, Pressure in Units IAS mph Knots "H2O "Hg PSI 40 34.8 0.79 0.06 0.028 50 43.4 1.23 0.09 0.044 60 52.1 1.77 0.13 0.064 70 60.8 2.41 0.18 0.087 80 69.5 3.15 0.23 0.114 90 78.2 4.00 0.29 0.144 100 86.9 4.94 0.36 0.178 110 95.6 5.98 0.44 0.216 120 104.3 7.12 0.52 0.257 130 113.0 8.37 0.62 0.302 140 121.7 9.72 0.71 0.351 150 130.3 11.17 0.82 0.403 160 139.0 12.72 0.94 0.460 170 147.7 14.39 1.06 0.520 180 156.4 16.15 1.19 0.583 190 165.1 18.03 1.33 0.651 200 173.8 20.01 1.47 0.722 210 182.5 22.10 1.62 0.798 220 191.2 24.29 1.79 0.877 230 199.9 26.60 1.96 0.961 240 208.6 29.03 2.13 1.048 250 217.2 31.56 2.32 1.140 260 225.9 34.21 2.52 1.236 270 234.6 36.98 2.72 1.335 280 243.3 39.86 2.93 1.440 290 252.0 42.87 3.15 1.548 300 260.7 45.99 3.38 1.661 ____________________________________ Yahoo! oneSearch: Finally, _mobile search that gives answers_ (http://us.rd.yahoo.com/evt=48252/*http://mobile.yahoo.com/mobileweb/onesearch?refer=1ONXIC) , not web links. ************************************** See what's free at http://www.aol.com. -------------------------------1178930533 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Yep, the table reflects the pressure that a pitot tube would see and co= uld=20 be used for calibration (maybe) of such a tube.    Think of i= t as=20 the maximum pressure that could be pitotically (invented word) obtained= if=20 there is no bleed off of the pressure by some sort of leak - like consuming=20= the=20 fuel in the tank.  1/2 the pressure sounds good for a vertical tube wit= h a=20 45 degree forward facing cut with the aforementioned leak.  Maybe it is= =20 less for a NACA duct.  It is preferable to have a slight positive press= ure=20 in a fuel tank provided by the vent. 
 
Uh, after all that, does this force water into the tank?  If the f= low=20 thru a NACA is backed up because it is impeded by back pressure, does water=20 enter the duct at all?  Is there yarn small enough, yet big enough to s= ee,=20 that could tell us the flow of water droplets about a teeny NACA?  I ha= ve=20 further questions, but my wife wants to go to dinner.  Tata for now..
 
Grayhawk
 
 
 
In a message dated 5/11/2007 7:16:36 P.M. Central Daylight Time,=20 kyrilian_av@yahoo.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
This table looks like simple dynamic pressure.
 
The third report referenced in Chris Z's post (NACA RM=20 A50E02) provides pressure recovery ratios for vario= us=20 mass flow ratios (discussion on p 5, plots on pages 14-20).  While it= =20 appears nothing was tested to ratios around zero (1/4 dia wing tank vent=20 lines at 15gph and 200 kts are in the 0.005 range--essentially zero),= =20 extrapolating a bunch makes me think we should expect mass flow ratios of=20= 0.5=20 to 0.8.  This is based on -2 to +2deg angle of attack at 0.3 Mach.&nb= sp;=20 So divide in half the pressures in the table below for a (maybe) conservat= ive=20 estimate.
 
- Kyrilian


Sky2high@aol.com wrote:
Mike, =20
 
 
Pressure in Units
IAS=20 mph
Knots
 "H2O
"Hg
PSI
 
 
 
 
 
40
34.8
0.79
0.06
0.028
50
43.4
1.23
0.09
0.044
60
52.1
1.77
0.13
0.064
70
60.8
2.41
0.18
0.087
80
69.5
3.15
0.23
0.114
90
78.2
4.00
0.29
0.144
100
86.9
4.94
0.36
0.178
110
95.6
5.98
0.44
0.216
120
104.3
7.12
0.52
0.257
130
113.0
8.37
0.62
0.302
140
121.7
9.72
0.71
0.351
150
130.3
11.17
0.82
0.403
160
139.0
12.72
0.94
0.460
170
147.7
14.39
1.06
0.520
180
156.4
16.15
1.19
0.583
190
165.1
18.03
1.33
0.651
200
173.8
20.01
1.47
0.722
210
182.5
22.10
1.62
0.798
220
191.2
24.29
1.79
0.877
230
199.9
26.60
1.96
0.961
240
208.6
29.03
2.13
1.048
250
217.2
31.56
2.32
1.140
260
225.9
34.21
2.52
1.236
270
234.6
36.98
2.72
1.335
280
243.3
39.86
2.93
1.440
290
252.0
42.87
3.15
1.548
300
260.7
45.99
3.38
1.661
 

Yahoo! oneSearch: Finally, mobile=20 search that gives answers, not web links.
 



See what's fre= e at AOL.com.=20=
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