Helicopter graph

**kiwiheli** · 02-25-2011, 07:43 AM

Hi there I am a helicopter pilot and was hoping that someone might be able to help me convert the power assurance chart for a turbine engine into an excel speed sheet to conduct the function of the chart when the engine figures are placed in it. The chart itself has several sections with “X” and “Y” axis that are not at right angles to each other and curved lines within the chart. I would be happy to email a copy of the chart to anyone that was willing to help as its very difficult to explain.

Hoping you might be able to help or direct me in the direction of someone who can.

Kind regards
Richard
The Helicopter Line
New Zealand

**6StringJazzer** · 02-25-2011, 11:13 PM

You could do this in Excel pretty easily but I think you would have to do it as three charts rather than one, because the Y ranges in each section are different units and different numerical ranges. (I have seen Andy Pope come up with some very creative ways of doing stuff like that, though.) You can certainly stack them together to serve exactly the same purpose.

I am puzzled by your statement that "“X” and “Y” axis that are not at right angles to each other." In the diagram you attached they sure look like they're at right angles to me.

Is the data empirical, or do you have equations that can generate it? If empirical, do you have the actual data?

I have always wanted to learn to fly a helicopter but if you have to do stuff like this then I have no hope

**6StringJazzer** · 02-28-2011, 11:09 PM

One challenge is that the % figures do not line up with the vertical gridlines on the chart. That is, 45% is aligned with the rightmost gridline but by the time we move left to 85%, it's in the middle of two gridlines instead of right on a gridline. So I calculated that there are 21 gridlines in 100%, and used that to eyeball the actual numbers plotted.

I am not sure how I could show gridlines at one frequency but labels at another, so my graphs have gridlines exactly every 5%. The plots match up with yours but the vertical lines aren't in the same place. Let me know if that's an issue.

The top chart is the trickiest because I had to make some assumptions about the shape of the curve. I assumed it was parabolic. However, I have been unable to tune the parameters to get it to match your chart. I will spend a little more time on it, if possible.

**Andy Pope** · 03-01-2011, 05:25 AM

6StringJazzer, the way you have constructed the lines is the approach I would take.

Basically you are going to have to construct the lines on the chart with dummy data series.
The different scaling can either be handled by 3 separate chartobjects or by rescaling the values and using another dummy series to label the 3 descrete sections of the Y axis.

For me the biggest issue though is not know enough detail about the chart and the data used to populate it. I don't know if all those angled and curved lines are standard on a chart or are actual data plots.

It would help to see a blank chart, a completed chart and the data used to complete it.