Airspeed indicator question

[FARF]

I recently purchased an aircraft with an airspeed indicator that I am not familiar with. It's a United Instruments 8100 series with a True Airspeed calibration in the top portion. I know what True airspeed is, I just do not know if the Indicated airspeed is being affected by the Temp/Altitude which can be set into the top window. Do I have to set a temperature correction and Altitude into this window to get a correct Indicated airspeed? The United Instrument company stated "Sorry to report that we do not offer any user manuals for our instruments". So not help there.
Thanks.

 

[GeorgeC]

Setting the pressure altitude and temperature lets you read off the TAS on the outer ring. IAS is unaffected.

 

[455 Bravo Uniform]

I believe you set your altitude over the outside temp and read your TAS in the white strip. IAS is on the black.

 

[RyanB]

It works just like any other airspeed indicator. The black knob on the instrument adjusts the altitude in the window at the top, it doesn’t affect the indicated airspeed.

Determine pressure altitude, and then match that with the OAT in Celsius and the readout is your TAS.

 

[FARF]

OK, thanks for the info.

 

[Bell206]

I just do not know if the Indicated airspeed is being affected by the Temp/Altitude which can be set into the top window.

The IAS side is separate and should not be affected. There are 2 inputs on these type indicators: pitot and static.

 

[NealRomeoGolf]

In this real life example I was at 7500 feet and it was 0 C. You'll see at the top I set 7500 over 0 by using the knob on the right. My IAS was nearly 150 and my TAS you can see was about 165.

 

[dmspilot]

It is like an E6B TAS calculator superimposed onto an airspeed indicator. As others have said, as you turn the knob to set pressure altitude and temperature, just the white strip in the lower left quadrant moves. Computed TAS is read on the white strip, IAS is read on the inner scale with the black background just like any other airspeed indicator. If you don't want to use the TAS calculator you can pretend it's not there.

 

[Ravioli]

@dmspilot for the best answer

I have a similar ASI but I have multiple other sources for TAS. I leave the mechanical one always oriented to IAS. But when Danger Zone isn't playing on XM Radio I'll play with it to assure it is working... just in case my other stuffs takes a nap.

TAS. There is no substitute. When bragging about your plane.