Airspeed Indicator Differences between piston and turboprops
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Airspeed Indicator Differences between piston and turboprops
Recently I noticed that C-210 or C-206 that had been fitted with a turboprop engine lack the yellow arc on the airspeed indicator.
Does anybody know why?
Does anybody know why?
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Squawk7777
I don't know.
There is no reason why they should be, as the airspeed limitations are a function of the airspeed structural limits rather than the type of power plant used to achieve them.
Thats why installing ecxess HP without a general and certified beefing up of the airframe, is interesting only for the rate of acceleration to the relevant speeds and higher climb rates.
Higher Cruise speeds are limited to the original VNO/VNE with perhaps a VA as the limit in any turbulance again unless there has been a certification ugrade to the airframe and controls.
It means you can cruise at speeds at or closer to these limits than you may have been able to with the std HP, but as always there is a price. Especially in the C210.
Putting a 5.7 litre Chevy in your Toyota Corrolla might get you going a bit faster in a straight line but the handling would be something else.
In any event it should be in the AFM if you have access to one.?
I don't know.
There is no reason why they should be, as the airspeed limitations are a function of the airspeed structural limits rather than the type of power plant used to achieve them.
Thats why installing ecxess HP without a general and certified beefing up of the airframe, is interesting only for the rate of acceleration to the relevant speeds and higher climb rates.
Higher Cruise speeds are limited to the original VNO/VNE with perhaps a VA as the limit in any turbulance again unless there has been a certification ugrade to the airframe and controls.
It means you can cruise at speeds at or closer to these limits than you may have been able to with the std HP, but as always there is a price. Especially in the C210.
Putting a 5.7 litre Chevy in your Toyota Corrolla might get you going a bit faster in a straight line but the handling would be something else.
In any event it should be in the AFM if you have access to one.?
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With US certificated turbine aircraft, there is no caution range (yellow band) because.....that is what the regulations say. However, when piston aeroplanes are re-engined with turbine powerplants, the Vne, which now becomes Vmo is sometimes reduced...but not always.
Recall years ago someone re-engined a C207 with an Allison turbine, and flew it very near Vmo all the time....until the wings came off over Mt. Wilson in southern California. The investigation revealed greatly elongated holes in the wing attach fittings.
Recall years ago someone re-engined a C207 with an Allison turbine, and flew it very near Vmo all the time....until the wings came off over Mt. Wilson in southern California. The investigation revealed greatly elongated holes in the wing attach fittings.
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A couple of points additional to 411A's comments ..
(a) the original post does not indicate the country of certification/registration so there may be local requirements or permissions to consider. For instance, I recall long ago (and my memory may be in error a little) that, in Oz, one didn't need the markings but, if they were there, they had to be correct.
(b) for the US case currently, 23.1545(b) requires the colour coding unless 23.1545(d) applies in that the aircraft has had Vmo/Mmo determined .. then some other requirements apply. This may be the answer and, I suspect, is what 411A is referring to .... Likewise I can't see much guidance in TSO-C2d.
(a) the original post does not indicate the country of certification/registration so there may be local requirements or permissions to consider. For instance, I recall long ago (and my memory may be in error a little) that, in Oz, one didn't need the markings but, if they were there, they had to be correct.
(b) for the US case currently, 23.1545(b) requires the colour coding unless 23.1545(d) applies in that the aircraft has had Vmo/Mmo determined .. then some other requirements apply. This may be the answer and, I suspect, is what 411A is referring to .... Likewise I can't see much guidance in TSO-C2d.
Last edited by john_tullamarine; 11th Apr 2002 at 06:51.
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As someone said Vmo in a turboprop or jet is equivalent to Vno in a piston, in that this is the speed at which the aircraft can withstand its design load limits (ie, +/- g under certification requirements, which I cannot think of at the moment).
The yellow arc, (Vno to Vne in a piston), or smooth air speed range as they call it, the aircraft is only designed to withstand a much reduced +/- g range.
So as most of the older and wiser pilots tell you, if you want to fly with the same safety margin to unexpected turbulence that turboprops and jets use, never ever fly in the yellow arc.
The yellow arc, (Vno to Vne in a piston), or smooth air speed range as they call it, the aircraft is only designed to withstand a much reduced +/- g range.
So as most of the older and wiser pilots tell you, if you want to fly with the same safety margin to unexpected turbulence that turboprops and jets use, never ever fly in the yellow arc.
