True Airspeed Chart

[HF17]

Is it just me, or does this chart not make sense. I’m not sure how to find the TAS with taking the temperature into consideration.

Sent from my iPhone using Tapatalk

 

[flyingron]

This chart has nothing to do with true airspeed. It is giving you the RPM needed to get a given rated power given OAT and pressure altitude.

 

[HF17]

This chart has nothing to do with true airspeed. It is giving you the RPM needed to get a given rated power given OAT and pressure altitude.

Oops. Wrong chart


Sent from my iPhone using Tapatalk

 

[HF17]

This chart has nothing to do with true airspeed. It is giving you the RPM needed to get a given rated power given OAT and pressure altitude.

I updated it


Sent from my iPhone using Tapatalk

 

[flyingron]

The chart assumes OAT = ISA. You can either use the temperature or the altitude.

 

[Clip4]

To use the chart precisely, you must convert intended altitude to pressure altitude.

 

[HF17]

To use the chart precisely, you must convert intended altitude to pressure altitude.

Yeah, but the part that is confusing is that you can’t include the temperature. It only assumes the temperature is standard


Sent from my iPhone using Tapatalk

 

[FastEddieB]

Yeah, but the part that is confusing is that you can’t include the temperature. It only assumes the temperature is standard

I think you’re supposed to first mark up from the OAT axis to where it meets the Pressure Altitude axis. Then, from that point look horizontally across to the performance parameters on the right side of the chart. The ISA line is just there for a Standard Day reference.

 

[HF17]

I think you’re supposed to first mark up from the OAT axis to where it meets the Pressure Altitude axis. Then, from that point look horizontally across to the performance parameters on the right side of the chart. The ISA line is just there for a Standard Day reference.

That’s what I initially thought, but no matter what temperature you use, it will correspond to the same pressure altitude


Sent from my iPhone using Tapatalk

 

[FastEddieB]

That’s what I initially thought, but no matter what temperature you use, it will correspond to the same pressure altitude

I see what you mean.

Is the chart maybe missing lines parallel to the ISA line that would bring OAT into play?

Or something like this?

 

[dmspilot]

Look at the chart label. It says "OAT = ISA". Look at the example. There is no adjustment for temperature.

 

[FastEddieB]

Look at the chart label. It says "OAT = ISA". Look at the example. There is no adjustment for temperature.

I guess a way around that is to compute the Density Altitude for the non-standard temperature and use that in lieu of Pressure Altitude on the vertical axis.

 

[HF17]

I guess a way around that is to compute the Density Altitude for the non-standard temperature and use that in lieu of Pressure Altitude on the vertical axis.

Yeah, that’s what I was thinking


Sent from my iPhone using Tapatalk