Dean Head wrote:
Paul,
Has there been any published calcs on the inlet area of a P-51 belly
mounted
for long ez/Cozy family?
Thanks
Dean
The original scoop on the Long EZ was the P51 type. The dimensions
should be on the Long EZ drawing. Does anybody have a copy lying
around?
Paul Lamar
Paul,
Are there any guides for calculating inlet area to get enough air flow and
sufficient differential pressure to cool the 13b. I realize this is
probably(surely) directly proportional the area and pressure drop across the
rad and oil coolers. Also, I assume I would use climb out as the entering
velocity of the air. Not sure what to use for the cowl exit pressure to
determine the DP. Atmospheric should be a conservative starting point. Maybe
if this data is not in one place I could gather it together into a
spreadsheet for others to use.
Thanks
Dean
We have been working on this for four years Dean :-)
All of the above is correct. My starting point is 30% of the core area.
I have been working on people to reduces the cowl exit pressure
by using cores mounted adjacent to the skin using louver type flaps.
This is some recent work on the subject which perhaps you missed.
The big problem is getting the data on the efficiency of the rads.
We need some real world measurements of the temp of the air exiting the rads.
You can use the assumptions and math out of this QB BASIC program.
Paul Lamar
The AirCraft Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/
Copyright 1998-2002 All world wide rights reserved.
Assumptions:
6000 BTU per minute waste heat
Specific heat of air = 0.01988 BTU per cubic foot per deg
20% humidity 100 degree day
Flow through rad is 7039 FPM or 80 MPH
____________________________________________
|air temp | airflow req | area | area |
| rise F | CFM | SF | SI |
--------------------------------------------
10 30303 4.31 620
15 20202 2.87 413
20 15152 2.15 310
25 12121 1.72 248
30 10101 1.44 207
35 8658 1.23 177
40 7576 1.08 155
45 6734 0.96 138
50 6061 0.86 124
55 5510 0.78 113
60 5051 0.72 103
Assumptions:
6000 BTU per minute waste heat
Specific heat of air = 0.01988 BTU per cubic foot per deg
20% humidity 100 degree day
Flow through rad is 8820 FPM or 100 MPH
____________________________________________
|air temp | airflow req | area | area |
| rise F | CFM | SF | SI |
--------------------------------------------
10 30303 3.44 495
15 20202 2.29 330
20 15152 1.72 247
25 12121 1.37 198
30 10101 1.15 165
35 8658 0.98 141
40 7576 0.86 124
45 6734 0.76 110
50 6061 0.69 99
55 5510 0.62 90
60 5051 0.57 82
Assumptions:
6000 BTU per minute waste heat
Specific heat of air = 0.01988 BTU per cubic foot per deg
20% humidity 100 degree day
Flow through rad is 10560 FPM or 120 MPH
____________________________________________
|air temp | airflow req | area | area |
| rise F | CFM | SF | SI |
--------------------------------------------
10 30303 2.87 413
15 20202 1.91 275
20 15152 1.43 207
25 12121 1.15 165
30 10101 0.96 138
35 8658 0.82 118
40 7576 0.72 103
45 6734 0.64 92
50 6061 0.57 83
55 5510 0.52 75
60 5051 0.48 69
CLS
'6000 BTU per minute waste heat
'0.01988 BTU per cubic foot per deg
'20% humidity 100 degree day
BTUCon = .01988
OPEN "btu.dat" FOR OUTPUT AS #1
PRINT #1, "Assumptions:"
PRINT #1, "6000 BTU per minute waste heat"
PRINT #1, "Specific heat of air = 0.01988 BTU per cubic foot per deg "
PRINT #1, "20% humidity 100 degree day"
PRINT #1, "Flow through rad is 7039 FPM or 80 MPH"
PRINT #1, "____________________________________________"
PRINT #1, "|air temp | airflow req | area | area |"
PRINT #1, "| rise F | CFM | SF | SI |"
PRINT #1, "--------------------------------------------"
FOR tempF = 10 TO 60 STEP 5
PRINT #1, tempF;
airflowCFM = (6000 / (.0198 * tempF))
PRINT #1, USING "############"; airflowCFM;
AreaSF = airflowCFM / 7039
PRINT #1, USING "###########.##"; AreaSF;
AreaSI = AreaSF * 144
PRINT #1, USING "###########"; AreaSI
NEXT tempF
CLOSE #1
'6000 BTU per minute waste heat
'0.01988 BTU per cubic foot per deg
'20% humidity 100 degree day
BTUCon = .01988
OPEN "btu.dat" FOR APPEND AS #1
PRINT #1, "Assumptions:"
PRINT #1, "6000 BTU per minute waste heat"
PRINT #1, "Specific heat of air = 0.01988 BTU per cubic foot per deg "
PRINT #1, "20% humidity 100 degree day"
PRINT #1, "Flow through rad is 8820 FPM or 100 MPH"
PRINT #1, "____________________________________________"
PRINT #1, "|air temp | airflow req | area | area |"
PRINT #1, "| rise F | CFM | SF | SI |"
PRINT #1, "--------------------------------------------"
FOR tempF = 10 TO 60 STEP 5
PRINT #1, tempF;
airflowCFM = (6000 / (.0198 * tempF))
PRINT #1, USING "############"; airflowCFM;
AreaSF = airflowCFM / 8820
PRINT #1, USING "###########.##"; AreaSF;
AreaSI = AreaSF * 144
PRINT #1, USING "###########"; AreaSI
NEXT tempF
CLOSE
'6000 BTU per minute waste heat
'0.01988 BTU per cubic foot per deg
'20% humidity 100 degree day
BTUCon = .01988
OPEN "btu.dat" FOR APPEND AS #1
PRINT #1, "Assumptions:"
PRINT #1, "6000 BTU per minute waste heat"
PRINT #1, "Specific heat of air = 0.01988 BTU per cubic foot per deg "
PRINT #1, "20% humidity 100 degree day"
PRINT #1, "Flow through rad is 10560 FPM or 120 MPH"
PRINT #1, "____________________________________________"
PRINT #1, "|air temp | airflow req | area | area |"
PRINT #1, "| rise F | CFM | SF | SI |"
PRINT #1, "--------------------------------------------"
FOR tempF = 10 TO 60 STEP 5
PRINT #1, tempF;
airflowCFM = (6000 / (.0198 * tempF))
PRINT #1, USING "############"; airflowCFM;
AreaSF = airflowCFM / 10560
PRINT #1, USING "###########.##"; AreaSF;
AreaSI = AreaSF * 144
PRINT #1, USING "###########"; AreaSI
NEXT tempF
CLOSE
SHELL "more < btu.dat"
SYSTEM
