the climbing rate gauge should have HUGE variations caused by atmosphere

[raaaid]

yeah then this guy was right:

the human balnce system works like the level glass of water, even nature is flawed spin for a while on yourself

perfect for a loop to do it cooridnated

and in case of thick fog perfect to go level

its the same than developing a trillion dollar biro to write in zero g

fork use a pencil

i hate the sciencepriests thinking the truth is democratic

edit:

also dont you wonder why they didnt paint the artificial horizont blue where it should be?

as it is its a totally pos for what you know you could be upside down and not be able to tell by the gauge

well the colour of the sky is a forbidden colour for macho men

maybe even more than pink you will never see a macho soldier dreess in this colour, so they didnt even paint the gauge like that

is a relaxing colour and calming like pink

[mazex]

Originally Posted by 5./JG27.Farber

Just totally ignore me...

I guess you guys were not there.........................................


mazex - what about that radar / command fighter thing your too busy to work on? any news?

I did put it on the shelf waiting for that last patch that before the summer was thought to include an SDK etc... So it's been on the shelf a lot longer than I thought And quite frankly I'm starting to lose in getting a decent patch these last weeks...

[SQB]

Originally Posted by IvanK

"doesnt actually a gyro artificial horizont also go crazy in hard manoubers?"

Depends on the gyro system. If its a full 360 degree in pitch and roll it works just fine no matter what you do. Few if any in WWII would have had this capability though.

Disregarding precession that is, no system imparts force perfectly.

[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.

[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.

Actually, pressure can change a lot at a particular level, that's why Altimeters are adjustable (barometric setting knob). This setting is most easily found when on the ground, just turn the knob till you have set the airfield elevation on the instrument. In flight, corrections must (practically) be sent by radio from weather or control centers and be relevant for the aircraft's location. Corrections are then, obviously, periodically needed during changing weather conditions. None of this really has any bearing on the vertical speed instrument, as it reacts to level altitude pressure changes (as while sitting on an airfield) much too quickly to register any vertical speed errors. Sit in a parked aircraft while a storm blows through and you won't see the VSI move at all.

[jf1981]

Originally Posted by zipper

In flight, corrections must (practically) be sent by radio from weather or control centers and be relevant for the aircraft's location.

Above 3000 ft agl we use standard reference 1013,25 (29.92), there would no point keeping accurate true altitude (some areas of the world, even impossible to know local pressure), only accurate pressure altitude is needed.

[nadasero]

Because of this I am using altimeters on my bike since about 20 years. They are very precise if it goes for altitude changes. They measure in steps of one Meter and if you hold them over your head, you get usually two meters more than on the ground.

Today I'm using a GPS-System (Garmin Edge 705). It has a barometric altimeter in addition to the GPS because this is more precise for small altitude changes. It gives precise readings for the steepness of a climb and the climbing speed.

The absolute precision is not that good. Over a day, the error can grow up to 100 meters if the weather changes. Typically it is less than 20 meters. A plane, flying from one weather system to the next can see changes of more than 50 mbar which can add up to an error of 500 meters at see level.

Originally Posted by jf1981

Above 3000 ft agl we use standard reference 1013,25 (29.92), there would no point keeping accurate true altitude (some areas of the world, even impossible to know local pressure), only accurate pressure altitude is needed.

Interesting. Here in the US we use pressure altitude (QNE) only for all aircraft above 18000 ft MSL. Below that the combination of not wanting aircraft flying into the ground (unintentionally) during airport operations with reduced visibility and having those aircraft (below 18000 ft), both terminal and en-route, synchronized vertically requires that they all set their altimeters to their local pressure settings (QNH). Any air traffic controller or Flight Service Station can provide local pressure information, and will give it (and winds, etc) spontaneously after querying intentions.

[jf1981]

Originally Posted by zipper

Interesting. Here in the US we use pressure altitude (QNE) only for all aircraft above 18000 ft MSL. Below that the combination of not wanting aircraft flying into the ground (unintentionally) during airport operations with reduced visibility and having those aircraft (below 18000 ft), both terminal and en-route, synchronized vertically requires that they all set their altimeters to their local pressure settings (QNH). Any air traffic controller or Flight Service Station can provide local pressure information, and will give it (and winds, etc) spontaneously after querying intentions.

Yes, in France depending upon where you are, the transition altitude varies, if not indicated 3000 ft used, but currently eg 5000 ft may be used instead in controlled areas. Apparet from that, it's flat land so in mountainous areas I really don't know what rules are applied there, we have some cities in the alps. Have to have a look at it.