Difference in sensitive and non sensitive altimeters?

[Bubbleboy]

Hi all....am looking at instruments for the Pietenpol. Can someone please fill me in on the difference between a sensitive and a non sensitive altimeter?

 

Scotty i_dunno

 

 

[Guest Sharp End]

From my training in the dim and distant past, a sensitive altimeter is usually equipped with a vibration system to keep the movement "alive". Without this system (ie a non-sensitive) the indicator needles can stick due to inertia, giving a false reading until the movement catches up with reality. Basically a sensitive altimeter will indicate more smoothly and accurately than a non-sensitive - hence the extra cost.

 

 

[Bubbleboy]

Thank you for that. I figured it would have to be something like that. Just looking, the sensitive gauges are double the cost but I feel worth the extra money. A potentially sticky dodgy ALT reading wouldnt be good!

 

Thanks mate :thumb_up:

 

Scotty

 

 

[facthunter]

Accuracy of Altimeter.

 

Re Sharp End.....the description is correct. There is a little vibrator that prevents "stiction" in the mechanism. Either way (with or without) the instrument can be accurate or not accurate. There is a tolerance where an altimeter registering outside of it is considered unserviceable. The reluctance of the needle to move can be corrected by tapping the face. The vibration would tend to cause wear and deterioration of the mechanism. This is the price you pay to have the instrument more responsive. I have no knowledge of an ASI fitted with such a feature, and it may not be necessary as you are dealing with larger increments of pressure change. Nev

 

 

[Bubbleboy]

Nev...I typed ASI for some stupid reason. I was referring to the Altimeter!

 

I appreciate the feedback. Learning a lot here!

 

Scotty

 

 

[facthunter]

Yes.

 

They may exist. It's just that I have never seen one. A lot of this information these days comes from an air-data computer ( I think). What I am saying is that I wouldn't buy the sensitive one, as it is no more accurate and engine vibrations may do the trick anyhow. You only need these sort of things if you are doing instrument flying. The worst instrument in the cockpit is the magnetic compass.. How is the Piet. going? Nev

 

 

[Barefootpilot]

A sensitive altimeter is one that gets upset when you don't fly it for a while or tell it you love it enough.... Sorry it is Friday!

 

 

[Bubbleboy]

Hey Barefoot...sounds like an EX-Girlfriend of mine...lol

 

Nev...it is coming along nicely although in the very early stages. I am awaiting my order of Spruce to arrive from the USA. Am drawing up the wing rib template. Just making a list of what I will need so I can budget. I want to do everything the right way so may take a little longer as funds become available. Thanks for your advice on the instruments, I appreciate it!

 

Scotty :thumb_up:

 

 

[djpacro]

My recollection of my theory notes from many years ago was that a non-sensitive altimeter did not have the barometric sub-scale to set QNH. Piston engine aircraft don't need an internal vibrator. When refreshing my memory on google just now I see an alternative definition of a non-sensitive altimeter as one having only one needle.

 

Speaking of specs - there is an FAA TSO on sensitive altimeters which refers to an SAE Standard on the subject of "Altimeters, Pressure Actuated Sensitive Type" - so obviously if an altimeter conforms to that TSO C-10b then it must be a sensitive altimeter. Sorry but I didn't persist to get a summary of the standard. Back to my catalogue and I see a variety of altimeters which do not claim that TSO - doesn't mean that they don't have the attributes required of that TSO however.

 

My point is that if an altimeter is missing just one, any one, aspect of that standard then it should not be described as a sensitive altimeter i.e. looks like both definitions in my first paragraph would be correct.

 

Regardless Bubbleboy - I suggest that you look at the specs and the pretty pictures in the catalogue or website vs the prices. Do you need a TSO'd instrument or not? Take your pick and pay your money.

 

Cue to mention CLEAR PROP here.

 

 

[Tracktop]

Just shooting from the hip ( or maybe from behind my back), but are the sensitive ones for use in gliders etc as I guess they would be much more interested in any small changes in height and climb / descent rates, and would want a more responsive device than required in powers ac?

 

 

[facthunter]

Extra instrument.

 

Then you use an IVSI, which is a sensitive vertical speed indicator. You would be flat out flying most jets manually at cruise height with passengers walking around and hold altitude within tolerance without one ( or V-bars that are just as responsive.). Nev.