Hi Bob and Richard,

Just a quick one on Linear P -Charts:

On page 3.19 of the Issue 6 Performance book, question 4 asks:

Find the Maximum Take off Weight permitted under the following circumstances:
TODA 950m
short dry grass
2% up
15 kt headwind
6000 ft Pressure Height
Temp +20 deg c

The available Answers are:
a) 810 kg (closest to the answer I got)
b) 700kg
c) 750 kg (the actual answer)
d) 730 kg

I have attached a scan of the chart which I draw out the line from the main body of the chart and intersect it with the specified runway length of 950m. Unless I am mistaken (and I could be) it would appear that the line of 2 deg slope and 15 kt headwind intersects the 950m TODA, it brings me to 810 KG, but the answer is less with 750 KG.

(if I examine the climb weight limit by extending the PH of 6000ft then I get a climb weight limit of 990 kg, but thats OK because 810kg and 750kg are both below this.

Can someone let me know where I am going wrong from the scan of the page 4 supplement chart?

Thanks

Brook

Hi Brook,

The chart is a bit tricky to read but I wonder, are you using the charts out of the old supplement? If not, here is a copy for downloading and printing out: www.bobtait.com.au/images/stories/bobtai...-PERF_Supplement.pdf

Here is my working for the problem:


First off, I get just a nudge over 750kg as the max weight for the take-off. Also the climb weight limit is 960kg (not 990 as you mentioned). Try it again on the newer chart (which is a direct copy of the one you'll get from CASA in the exam) and if it still borks check out my working for it,

Cheers,

Rich

Thanks Richard,

Downloaded the new supplement, did the workings and I too got close to 750KG.

Thanks for that, the book I bought must have had the old supplement in it. Makes me feel better I'm not completely mad!

Brook

Great, glad it worked out

Cheers,

Rich