the climbing rate gauge should have HUGE variations caused by atmosphere

[raaaid]

if i were to build a climbing rate gauge i would do it base on vertical angle of heading and air speed

but as this was made by science people i bet they linked the altitude gauge based on atmospheric pressure and its gradient be the climbing rate

but now think that when your flying your going from high to low pressure though you dont change altitude

so my question: shouldnt realistic altitude gauges oscillate A LOT both climbing rate and height?

[bolox]

Try the manual for the original to see how it works
http://www.mediafire.com/download.php?awc18q83pf6w8q0

[raaaid]

thanks

from your link:

The K.B.B. Rate of Climb Indicator
Mark IB* is a simple means of measuring
the rate of change of atmospheric pressure
due to change in altitude of the
aircraft in which the instrument is fitted

as i predicted this scienpriests went for the obvious path

do you know what turbulences are?

sub and overpresures, they happen all the time so the climbing indicator goes crazy

the elemental way to fix this flaw is to link airspeed and angle of climb to have a precise climbing rate reading

edit:

its an edicated guess wflying really low the altitude gauge can even read negative :O

[gabuzomeu]

Absolutely,
except perhaps if IAS <>TAS and the air itself does move up and down very fast (let's say we could call this phenomenon.... wind?)

[raaaid]

oh but the vertical wind maybe a maxium of 20 kph while the horizoantal whcih measures the plane +-400 so the error is much less than with the flawed transformed barometer

[Skoshi Tiger]

You could use your radar altimeter? Might be more accurate but would be dependant on the terrain beneath you, or a GPS, or inertal navigation system, or one of those laser gyroscope dodads. It would just be a data gathering and programming issue.


Hmmmm! What did they teach in the BAK syllabus? "High to low lookout below?"

[bolox]

the elemental way to fix this flaw is to link airspeed and angle of climb to have a precise climbing rate reading

However the ASI is part of the same Pitot Static system and thus prone to the same errors

[jf1981]

Originally Posted by raaaid

do you know what turbulences are?

sub and overpresures, they happen all the time so the climbing indicator goes crazy

It makes no big deal, even today's airplane set their instrument to the standard pressure passed a certain heigh. That means they effectively do not fly at a constant height from the ground, depending upon environmental pressure, but they accurately fly on a so called "flight level" or FL. All aircrafts in the same area have the same reference, this is all that matters when flying high.

the elemental way to fix this flaw is to link airspeed and angle of climb to have a precise climbing rate reading

Altimeter and vertical speed indicator both use the same pressure, the only error is height/altitude because we do not know the local pressure unless we ask for it. Again that's not a problem at all since we just fly on a standard reference passed 3000 ft AGL. We make a little bit of yoyo if the local pressure changes across our path but it does'nt change that much and that fast where you could notice from inside it has changed. It's so smooth that it does'nt affect the flight.

its an educated guess wflying really low the altitude gauge can even read negative :O

Yes true, but that's why we always need to know the local pressure when getting below 3000 ft agl. That's not talking about cliffs of dover because we don't care doing belly landings anyway

Basically, you should set your gage before taking off to either actual field altitude or zero if you would like to have a correct reference. If your field is close from the sea level and today's local pressure is very low, you may well read a negative number in the first place. If you would like to land where the local pressure may be very much different, you better ask for the local pressure before going low.


There's no other logical way than having VSI and altimeter using the same references, either both based on local pressure measurement, or both on calculus, if not, they would could show different things eg altimeter climbing but zero vsi. And there's no way to base altimeter on your method. You also forget that such VSI does'nt know the vertical winds, if you pass through a "wind pump" shortly before landing, the instrument would'nt recognize it. Could be dangerous. If you add the facts that such an instruments needs to know angle of attack ... more complicated, error induced if there's vertical wind locally, requires accurate measurement of pitch and angle of attack, needs true air speed (ias is not enough, so it also needs to know ias + altitude) ???

basically, the design you called for requires :

- Altitude
- Indicated air speed
- Pitch angle from gyro (with very good accuracy)
- Angle of attack (very good accuracy)

To go into one instrument, the VSI, out of what it can calculate only vertical speed but would'nt show the correct value if there is vertical wind.
Preferably, the instrument should not need electricity, if it would, please add to "requirements", and if so, an electrical failure would make for the VSI failure.

I think Einstein said "as simple as can be, but not more". That is what we currently have. I would ask you to design other aircraft systems, unless you really understand the statement in italic. Things sometimes look simple when they are not.

Just a touch of humour if you allow me, it makes me think of George Clooney's words "Gyro VSI, what else ... does it need ?", the standard instrument does only need one static pressure source if I'm right.

[mazex]

Originally Posted by raaaid

if i were to build a climbing rate gauge i would do it base on vertical angle of heading and air speed

Well -that's how a computer game designer would think maybe

For a starter - even if it was a good idea, how would you calculate a "vertical angle of heading"? How about AOA (angle of attack) for example? And if you could get the real "vertical angle of heading" - it would have to no use as the aircraft "longitudinal angle" would only be related the air that surrounds the aircraft... And what if that air is moving up or down (which is the thing that happens up there IRL accept a dead calm winter day)? What good would then the fact that the aircraft "moves at an angle of 2 degrees at 200 Mph" do you if the air surrounding the aircraft moves down at 8 m/s? What is the real rate of climb (or descent) then?

Do some reading on variometers as there are a lot of parameters to consider accept the 1940 versions that actually only worked on atmospheric pressure rise/drop that gave many problems...

Start here for example:

http://en.wikipedia.org/wiki/Variometer

EDIT: And no - if you climb through non-turbulent air they don't oscillate (accept for engine vibrations )... In turbulent air the problem is mostly that they oscillate to little compared to reality

[jf1981]

Originally Posted by raaaid

if i were to build a climbing rate gauge i would do it base on vertical angle of heading and air speed

That means accurately knowing you angle of attack and pitch angle. In aeroplanes, the simpler and more reliable design prevails.

but as this was made by science people i bet they linked the altitude gauge based on atmospheric pressure and its gradient be the climbing rate

You don't understand how complicated it is to have accurate pitch and angle of attack values. Both required if you would calculate the VS. Not to mention the fact that such instrument has 3 input, aoa, pitch and speed, it needs to makes sinus (aoa+pitch) x speed, how to you make such an instrument ? Pratcically, I don't see, and if electric failure what happens ? Want to design such an instrument with just mechanics ... not so easy.

but now think that when your flying your going from high to low pressure though you dont change altitude

Answered in next post.

so my question: shouldnt realistic altitude gauges oscillate A LOT both climbing rate and height?

Wether systems dynamic is much slower than aircraft dynamics, hence it does'nt affect the flight.
We prefer to change height when local pressure changes by maintaining the same pressure altitude (that is far from the ground, when flying "flight level" which are reffered to standard ground pressure 1013,25 / 29.92). Close from ground, calibrating the altimeter is needed, but the VSD is not affected by local pressure changes because it is too slow. So answer is no for climb rate, yes for altitude but we do with that no big deal (below 3000 ft agl), and we just don't mind above that altitude (altimeter set to std reference pressure).

In real life airlpanes do not fly at constant height, they follow the pressure lines yes that's what you just discovered through your initial question.