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fly37 View Drop Down
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    Posted: 05 Nov 2013 at 2:09am
It is possible know what is the limits rnw for a DC8 for landing and take off? 
The shorter which the dc8 can use?

thanks

fly37  Gianni
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yankeeromeo View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yankeeromeo Quote  Post ReplyReply Direct Link To This Post Posted: 05 Nov 2013 at 7:12am
Hello,
that's depending on your GW, airport altitude, wind condition, temperature and, of course, the runway condition.
But let's say perfect condition, 0 wind, dry runway, airport @ sea level altitude for a 
DC-8-40 weighing 180'000 pds =  6'700Ft of runway to land.
For a DC-8-50 could be even 6'000 Ft, same conditions.
Cheers.
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Paul Golding View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul Golding Quote  Post ReplyReply Direct Link To This Post Posted: 05 Nov 2013 at 7:37am
Last night I managed to take off from a 5,300 ft runway in a 40 series with the default load (12,000 over gross max), with flaps and trim set to zero........and have now filed a support request.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fly37 Quote  Post ReplyReply Direct Link To This Post Posted: 05 Nov 2013 at 12:48pm
Thank you yankeeromeo for the clear answer! very appreciate

fly37 Gianni
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jdetrick Quote  Post ReplyReply Direct Link To This Post Posted: 05 Nov 2013 at 1:44pm
I've to agree.  Who ever did the air files and Beta testing really screwed the pooch.
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Paul Golding View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul Golding Quote  Post ReplyReply Direct Link To This Post Posted: 05 Nov 2013 at 4:11pm
Originally posted by jdetrick jdetrick wrote:

I've to agree.  Who ever did the air files and Beta testing really screwed the pooch.
 
Late last night after finding out about the accidental STOL characteristics, I was messing about with a few of my own files from days gone by.  After some yawning and dozing, I managed to end up stalling the DC-8 and crashing.  I was pleasantly surprised to say the least, as it hadn't done this before.  After the DC-8 re-loaded at the same airport with the short runway mentioned above, I reduced the weight and tried a take-off with some flap and nose up trim (still find it weird to be in a DC aircraft with no nasty trim horn blaring away).  Just before leaving the end of the runway and bouncing off across some farmland, I noticed that the EPR readings were much lower than previous flights..............after crashing before leaving the ground, I had a look at what I'd been doing whilst half asleep and discovered that the air file had been replaced by one I was involved in for a 707!
 
Anyway, point of the boring story is that I imagine someone will fix the flight model a lot quicker than many of the issues you mentioned previously John.  Talking of which, have you gone through the support link to report these?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jdetrick Quote  Post ReplyReply Direct Link To This Post Posted: 05 Nov 2013 at 6:54pm
I'm messing around a bit with the air files and cfg to come up with a workable solution.
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fly37 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fly37 Quote  Post ReplyReply Direct Link To This Post Posted: 05 Nov 2013 at 8:22pm
nice to know! Thanks

fly37
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike70 Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 2:28am
From an Air Canada data sheet for a -40:
They say normally to use F(25) except as shown for higher altitudes. I provide 3550 MSL as one example.
 
GW is in thousands of pounds (K lbs), distance in feet., V speeds in knots
 
SL 15 deg C            3550 MSL 8 deg C
       FLAPS 25             FLAPS 25  /  (FLAPS 15)  
GW  VR   V2  Dist     VR   V2   Dist
315 151 162 9700    158 167 12900 (Flaps 15 ONLY)
310 150 160 9400    157 166 10600 (Flaps 15 ONLY)
300 147 158 8800    148 157 10750
290 144 155 8300    145 154 10050
280 142 152 7700    143 152 9400
270 138 150 7200    139 149 8750
260 135 147 6850    136 147 8150
250 132 146 6675    133 145 7550
240 130 145 6525    130 142 7000
below 240K use 240 V speeds     
   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike70 Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 2:46am
Also from Air Canada for a -40: 35 and 50 deg flaps, same deal  -K lbs, KIAS
GW         F(35)           F(50)
  Vref Vapp Vref Vapp
207 136 146 134 144
200 134 144 131 141
190 130 140 127 137
180 127 137 124 134
170 123 133 124 134
160 119 129 124 134
150 116 126 124 134
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fly37 Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 2:49am
thank Mike70!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yankeeromeo Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 7:42am
Originally posted by jdetrick jdetrick wrote:

I'm messing around a bit with the air files and cfg to come up with a workable solution.

what's the content/purpose of the AIR file and which relation with the Aircraft cfg ?
need to know more before messing all...
thanks in advance.
Cheers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul Golding Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 9:02am
Originally posted by yankeeromeo yankeeromeo wrote:

Originally posted by jdetrick jdetrick wrote:

I'm messing around a bit with the air files and cfg to come up with a workable solution.

what's the content/purpose of the AIR file and which relation with the Aircraft cfg ?
need to know more before messing all...
thanks in advance.
Cheers.
 
That would need a big explanation and I think google is probably better for providing things for you to read.  But briefly, the air file traditionally contained all the parameters that effected the way an aircraft behaved, from weights, dimensions, capacities and thrust, to position of lights, drag, lift and mean wing chord. Many 100's of settings.  Some of these now also appear in the aircraft.cfg file, presumably because it's easier for people to edit them in say, notepad, rather than an air file editor.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul Golding Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 9:07am
Originally posted by Mike70 Mike70 wrote:

From an Air Canada data sheet for a -40:
They say normally to use F(25) except as shown for higher altitudes. I provide 3550 MSL as one example.
 
GW is in thousands of pounds (K lbs), distance in feet., V speeds in knots
 
SL 15 deg C            3550 MSL 8 deg C
       FLAPS 25             FLAPS 25  /  (FLAPS 15)  
GW  VR   V2  Dist     VR   V2   Dist
315 151 162 9700    158 167 12900 (Flaps 15 ONLY)
310 150 160 9400    157 166 10600 (Flaps 15 ONLY)
300 147 158 8800    148 157 10750
290 144 155 8300    145 154 10050
280 142 152 7700    143 152 9400
270 138 150 7200    139 149 8750
260 135 147 6850    136 147 8150
250 132 146 6675    133 145 7550
240 130 145 6525    130 142 7000
below 240K use 240 V speeds     
   
 
It would be interesting to know where the flight dynamics guy got his numbers from, given that I can take off from a 5,300 ft (50ft MSL) runway and clear trees etc whilst being 12,000 over max GW and using 0 flap and 0 trim and being in the air before reaching 140kts.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yankeeromeo Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 10:04am
Originally posted by Paul Golding Paul Golding wrote:

Originally posted by yankeeromeo yankeeromeo wrote:

Originally posted by jdetrick jdetrick wrote:

I'm messing around a bit with the air files and cfg to come up with a workable solution.

what's the content/purpose of the AIR file and which relation with the Aircraft cfg ?
need to know more before messing all...
thanks in advance.
Cheers.
 
That would need a big explanation and I think google is probably better for providing things for you to read.  But briefly, the air file traditionally contained all the parameters that effected the way an aircraft behaved, from weights, dimensions, capacities and thrust, to position of lights, drag, lift and mean wing chord. Many 100's of settings.  Some of these now also appear in the aircraft.cfg file, presumably because it's easier for people to edit them in say, notepad, rather than an air file editor.
 

Thank you Paul for you explanations.
Just to be clear, is modifying the Aircraft cfg enough, without modifying the Air file ?
Thanks in advance.
Cheers.
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Paul Golding View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul Golding Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 10:14am
Kind of, yes.
 
If what you want to change appears in the cfg file, then this overrides whatever the same value is in the air file, for example the static thrust.  The problem is that many more variables are in the air file than the cfg file, and almost every change that's made will have some effect on another parameter.  For example, increasing the drag will not only affect speed at any given power setting, but it will also affect take-off roll, acceleration, fuel consumption etc
 
The trick is to keep a copy of the file you're about to edit and reload and test the aircraft after each change........and write lots and lots of notes!
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yankeeromeo View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yankeeromeo Quote  Post ReplyReply Direct Link To This Post Posted: 06 Nov 2013 at 10:16am
totally aware of and agree too Paul.
Thanks for the confirmation.
Now back to work the CfgOuch
Cheers.
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