[JTO24]

Between a post elsewhere today of the 747 that stalled and crashed due to cargo shifting and these post of crashed planes due to clogged pitot tubes, I'd say I'm stoked for my business trip next week haha

[tlp]

Originally Posted by TrevorM3

science and laughs all in one thread.

[V1.47fan]

Originally Posted by CanAutM3

But oh yes they do, INS systems used accelerometers to establish ground speed and then establish position relative to the ground. And yes, it is old tech.

When did I ever mention that accelerometers were used to establish airspeed . I agree, pitot are the only accurate and reliable measure of air speed.

When the plane flies in a straight line, the position is established through the ground speed calculated by the on-board accelerometers.

You posted something false, then when someone try to correct you, you bring up Off Topic.

Accelerometers dont calculate groundspeed, accelerometers have no way of knowing if there's a headwind or tailwind, outside pressure and temperature.

To determine ground speed, you start with indicated airspeed, then convert it Calibrated airspeed, then find True Airspeed which is Calibrated Airspeed corrected for non standard temperature and pressure and Ground speed is true airspeed corrected for wind.

Before GPS, ground speed was determined on commercial flights by the triangulation of waypoints (Rnav's), Navaids( VOR's, radio beacons etc.)

And planes today dont even use INS, how can you say that's how planes determine GS today? It estimated the position based on time flown time , using bearing etc. And last known airport.( Not using accelerometers) It wasnt even the primary mode of navigation, it wasnt the most accurate that's why they're not in use anymore.

[Noisygriff]

Originally Posted by V1.47fan

...Accelerometers dont calculate groundspeed, accelerometers have no way of knowing if there's a headwind or tailwind, outside pressure and temperature.

To determine ground speed, you start with indicated airspeed, then convert it Calibrated airspeed, then find True Airspeed which is Calibrated Airspeed corrected for non standard temperature and pressure and Ground speed is true airspeed corrected for wind...

I love a bit of off topic. You are close........ but wrong, I'm afraid.

Many current generation avionic systems use accelerometers to determine a velocity. It's the primary means of determining vertical speed on the type I fly, for example.

Accelerometers don't calculate anything. Their output can be used to determine all sorts of things, including groundspeed. Your assertion about how groundspeed is derived (by apparently converting IAS into every kind of airspeed known to man) is the wrong way round. The airspeed and heading are compared to the groundspeed and track (from GPS and, occasionally, accelerometers) to determine the wind velocity.

Very happy to be proved wrong...

Back on topic. I really feel for the guy in the M4. He made a mistake which hurt his pride and his wallet. But that's all. No-one and nothing else was damaged. I hope the car can be fixed quickly and that he can find his mojo again to enjoy it. Chin up!

[V1.47fan]

Originally Posted by Noisygriff

I love a bit of off topic. You are close........ but wrong, I'm afraid.

Many current generation avionic systems use accelerometers to determine a velocity. It's the primary means of determining vertical speed on the type I fly, for example.

Accelerometers don't calculate anything. Their output can be used to determine all sorts of things, including groundspeed. Your assertion about how groundspeed is derived (by apparently converting IAS into every kind of airspeed known to man) is the wrong way round. The airspeed and heading are compared to the groundspeed and track (from GPS and, occasionally, accelerometers) to determine the wind velocity.

Very happy to be proved wrong...

Back on topic. I really feel for the guy in the M4. He made a mistake which hurt his pride and his wallet. But that's all. No-one and nothing else was damaged. I hope the car can be fixed quickly and that he can find his mojo again to enjoy it. Chin up!

A vertical speed indicator determines the rate of climb, it doesnt give you IAS or ground speed and yes some VSI's use accelerometers.
Accelerometers measures g forces, not ground speed or airspeed.
That's why modern airliners (to the latest 787, A350) still rely on the old pitot-static system for airspeed.



Vertical Speed Indicator.


look at the Boeing pitot-static system, it incorporates the Airspeed indicator and altimeter.






If you've figured out a different way to determine airspeed using accelerometers you should share it with the world.

[MrPrena]

That was a great review of Freshman Classical/Mechanical Physics for a day.

[dreamingat30fps]

[deeLow]

You guys blew my mind. I'm gonna leave this thread and never return now

[MrPrena]

Originally Posted by dreamingat30fps

[CanAutM3]

Originally Posted by V1.47fan

You posted something false, then when someone try to correct you, you bring up Off Topic.

I still don't believe that I have posted anything false. Now that this discussion is in its own thread, I don't need to call OT anymore

From Wikipedia:

Inertial navigation is a self-contained navigation technique in which measurements provided by accelerometers and gyroscopes are used to track the position and orientation of an object relative to a known starting point, orientation and velocity. Inertial measurement unit (IMUs) typically contain three orthogonal rate-gyroscopes and three orthogonal accelerometers, measuring angular velocity and linear acceleration respectively. By processing signals from these devices it is possible to track the position and orientation of a device.

Originally Posted by V1.47fan

Accelerometers dont calculate groundspeed, accelerometers have no way of knowing if there's a headwind or tailwind, outside pressure and temperature.

You don't need to know wind speed or direction when calculating ground speed from accelerometer data. Accelerometers measure acceleration. With acceleration and time, speed and distance relative to the ground can be calculated. First year of physics...

Originally Posted by V1.47fan

To determine ground speed, you start with indicated airspeed, then convert it Calibrated airspeed, then find True Airspeed which is Calibrated Airspeed corrected for non standard temperature and pressure and Ground speed is true airspeed corrected for wind.

And how do you accurately measure wind speed and direction?

Originally Posted by V1.47fan

Before GPS, ground speed was determined on commercial flights by the triangulation of waypoints (Rnav's), Navaids( VOR's, radio beacons etc.)

When flying over the ocean, where no VOR was available, how did the pilots figure their position relative to the ground before GPS? INS was one system available to them.

Originally Posted by V1.47fan

And planes today dont even use INS, how can you say that's how planes determine GS today?

I never said they did. They don't need to because we now have GPS. Some planes are still equipped with INS as a redundant system though.

Originally Posted by V1.47fan

It estimated the position based on time flown time , using bearing etc. And last known airport.( Not using accelerometers)

How do you estimate position only with time flown and origin?

You also need groundspeed to do that (distance = time x speed), and groundspeed is calculated based on acceleration data from accelerometers.

[CanAutM3]

Originally Posted by V1.47fan

A vertical speed indicator determines the rate of climb, it doesnt give you IAS or ground speed and yes some VSI's use accelerometers.
Accelerometers measures g forces, not ground speed or airspeed.
That's why modern airliners (to the latest 787, A350) still rely on the old pitot-static system for airspeed.



Vertical Speed Indicator.


look at the Boeing pitot-static system, it incorporates the Airspeed indicator and altimeter.






If you've figured out a different way to determine airspeed using accelerometers you should share it with the world.

You're the one that brought air speed and pitot tubes in the discussion. The discussion started with gyroscopes in aircraft navigation systems... airspeed was never a point of discussion.

[CanAutM3]

Originally Posted by Boss330

Trying to keep this OT

Your profile pic needs updating

Waiting for a good track pic of my M4

[Maestro]

Yes a torque effect of a rotating mass has much to due with what the car pull or pushes itself in a particular direction. If you lift a vehicle off the ground and gun the motor with the wheels moving you will feel the car pull in accordance to the right hand rule. Also this why rear ends have thrust bearings to keep the axles from pushing into the housing. Not to say they car can not push out to the left, but other things are have total effect on this like how weight maybe distributed in the car or traction on each wheel and whether you have positraction.

As wheel spins on a shaft in the forward direction it will push the axle into the housing and their will be an equal force pushing the car to the right and once the force exceed the tire fiction the car will move to the right.

[UncleWede]

So, without a pitot or accelerometer, how do you calculate the ground speed of an unladen swallow?????

[MYovichZ4]

Originally Posted by UncleWede

So, without a pitot or accelerometer, how do you calculate the ground speed of an unladen swallow?????

[Noisygriff]

Originally Posted by V1.47fan

A vertical speed indicator determines the rate of climb, it doesnt give you IAS or ground speed and yes some VSI's use accelerometers.
Accelerometers measures g forces, not ground speed or airspeed.
That's why modern airliners (to the latest 787, A350) still rely on the old pitot-static system for airspeed.

...f you've figured out a different way to determine airspeed using accelerometers you should share it with the world.

You're right. However, you are also the only one talking about airspeed and accelerometers. The discussion started talking about ground speed.

Ground speed is simply a velocity, as is vertical speed. Accelerometers can be used to determine either (knowing how much the aircraft has accelerated means that the speed can be derived).

The primary source for most modern aircraft's vertical speed is now accelerometers (pitot system as a backup - the diagram is old skool tech). The primary source of groundspeed is GPS, but there is often an accelerometer-based back-up in case GPS signal is lost. This is much more accurate that the old gyro-based inertial nav systems.

The only source for airspeed is the pitot-static system.

So, in sum. Groundspeed is available using accelerometers as the data source. Airspeed is not - but then that's not what we started talking about.

Enough nerding - I'm off for a glass of wine!

[Noisygriff]

Originally Posted by UncleWede

So, without a pitot or accelerometer, how do you calculate the ground speed of an unladen swallow?????

African or European?

The equation above only applies to the European.

[UncleWede]

^ I thought he provided the African, hence the A0 term in the equation.

[upstatedoc]

Originally Posted by Noisygriff

Enough nerding - I'm off for a glass of wine!

Well, I guess it's 5 o'clock somewhere.

[Noisygriff]

Originally Posted by UncleWede

^ I thought he provided the African, hence the A0 term in the equation.

I've had that glass of wine now and I realise that I have made a terrible mistake. You are right and everything I thought I know about European Swallows has been shot to pieces.

I have wasted my life!

[MrPrena]

Originally Posted by Noisygriff

Enough nerding - I'm off for a glass of wine!

Thanks for being a nerd guys. Now, I look like a cool kidz here.

[UncleWede]

Originally Posted by Noisygriff

I've had that glass of wine now and I realise that I have made a terrible mistake. You are right and everything I thought I know about European Swallows has been shot to pieces.

I have wasted my life!

Not at all. If you stop learning then you are wasting your life