Simviation Forums

1. I've been flying in Baron 58 and he has a HSI. Is there a way for the HSI to show you where the VOR is right at that instant from you? The HSI in Baron can only be used to align with the VOR at a specific course, but the F-16s HSI has a little triangle which is called a BEARING POINTER on the HSI (not the TO/FROM indicator) that shows you where the TACAN is right at that moment. You then just turn to put the triangle at the top of the HSI heading and you're heading right at it. But the only way in Baron I can think of to find where the VOR is at that instant is to rotate the course deviation arrow on the HSI until it aligns. Then I know the course where it is from me at that moment. This is also the only trick I can use in a Cessna on the simple VOR1 ad VOR2 instruments to find the VOR.

2. The Radio magnetic indicator which shows the VOR2 shows I think where the VOR is from the aircraft, right? I can use RMI then but what if I need it for something else?

BTW does the Radio magnetic indicator have a gyro? I think he works all the time, even when the Battery is off.

3. The DME shows ground speed in the aircraft. Is that the ground speed in relation to the VOR or the real ground speed of the aircraft? Because when I'm heading right at the VOR it's always higher than when I'm not flying directly at it.

1. I've been flying in Baron 58 and he has a HSI. Is there a way for the HSI to show you where the VOR is right at that instant from you? The HSI in Baron can only be used to align with the VOR at a specific course, but the F-16s HSI has a little triangle which is called a BEARING POINTER on the HSI (not the TO/FROM indicator) that shows you where the TACAN is right at that moment. You then just turn to put the triangle at the top of the HSI heading and you're heading right at it. But the only way in Baron I can think of to find where the VOR is at that instant is to rotate the course deviation arrow on the HSI until it aligns. Then I know the course where it is from me at that moment. This is also the only trick I can use in a Cessna on the simple VOR1 ad VOR2 instruments to find the VOR.

2. The Radio magnetic indicator which shows the VOR2 shows I think where the VOR is from the aircraft, right? I can use RMI then but what if I need it for something else?

BTW does the Radio magnetic indicator have a gyro? I think he works all the time, even when the Battery is off.

3. The DME shows ground speed in the aircraft. Is that the ground speed in relation to the VOR or the real ground speed of the aircraft? Because when I'm heading right at the VOR it's always higher than when I'm not flying directly at it.

1)  That is the limitations of an HSI... it's really just a regular VOR indicator, inside of a Heading indicator.  Spinning the course(OBS) until the needle centers, is the only way to get an immediate bearing on the station.

2) Yes.. an RMI treats a VOR as if it were an NDB.. it "points" to the station.  Part of what an RMI is, is that it is magnetically slaved.. as in, it's compass-card stays aligned like a magnetic compass. (hence the 'M' in RMI)

3) A DME (equipped for this)(some are not), shows you your closure speed to the station. For example: If you were flying a perfect DME arc, the DME speed would be zero.

2) Yes.. an RMI treats a VOR as if it were an NDB.. it "points" to the station.  Part of what an RMI is, is that it is magnetically slaved.. as in, it's compass-card stays aligned like a magnetic compass. (hence the 'M' in RMI)

So does it mean that it doesn't have it's own gyro like a heading indicator or HSI? I read somewhere that it uses a "slaved gyro" which means that his heading indicator is connected to a magnetic compass. I don't know which magnetic compass, the one you can see in the cockpit or his own magnetic compass which can't bee seen?

So does it mean that it doesn't have it's own gyro like a heading indicator or HSI? I read somewhere that it uses a "slaved gyro" which means that his heading indicator is connected to a magnetic compass. I don't know which magnetic compass, the one you can see in the cockpit or his own magnetic compass which can't bee seen?

It's not slaved to the magnetic compass that you can see. That is a completely independent device (for simplicity and reliability). I've read that it IS slaved to that compass.. but that makes no sense because it does not exhibit compass errors durng turns. Most High-quality HSIs are similar, in that you do not need to constantly cross-check them against the magnetic compass (they're always correct and also show no turning errors).

THere is some sort of "compass system" that these devices rely upon, and I honestly do not know how it works.

I believe the RMI can be connected to a Magnetic Slaving Transmitter http://www.pilotoutlook.com/instrument_flying/remote_indicating_compass

or a  Remote Compass module. http://www.dynonavionics.com/docs/D100_Feature_Compass.html

Do those digital HSIs and AIs found in a Boeing 737, Boeing 747 or in a Bombardier Learjet also have a gyro like a normal HSI? They do, right? But they only display the information on a screen. It's weird that no gyro spinning is heard after switching the battery on.

Do those digital HSIs and AIs found in a Boeing 737, Boeing 747 or in a Bombardier Learjet also have a gyro like a normal HSI? They do, right? But they only display the information on a screen. It's weird that no gyro spinning is heard after switching the battery on.

So does anybody know do those digital HSIs and AIs have a gyro or they work on some other principle?

Basically, a HSI is just an electronic solution for combining a VOR or other NaV display with a DG.

There is a gyro inside, but there is no mechanically-linked card like an ordinary DG. The electronic interface between the screen and the gyro also allows the RMI function. This quote from a mfr's site explains it more:

"The HSI, or Horizontal Navigation Indicator or Pictorial Navigation Indicator, is perhaps one of the most useful although misunderstood instruments around. Very simply, it combines your directional gyro and Nav indicator into one instrument that reduces pilot workload by providing heading, course reference, course deviation and glide slope information all in one visual aid.

In addition, an HSI makes it easier to visualize the aircraft's position with reference to the selected course or holding patterns. The "split needle" presentation made up of the course and reciprocal pointers and the VOR/LOC deviation indicators clearly shows both selected course and course deviation. It gives standard sensing and course deviation indication on back course ILS approaches, provided the front course heading is set under the head of the course pointer and you fly toward the course deviation indicator. It also provides convenient 45 degree tic marks to help visualize procedure turns and reciprocals so that you don't need to memorize outbound/inbound headings or add/subtract 45 degrees for intercepts or offsets. A heading bug is provided for autopilot coupling or as a heading reminder if your aircraft is not equipped with an autopilot.

You may also consider a slaved HSI. Slaving automatically compensates for gyro heading errors and keeps your HSI in agreement with your compass. It uses a magnetic flux sensor mounted in the wing or tail of your aircraft to sense changes in magnetic heading and sends corrective signals to your HSI. You can even add an RMI Bootstrap that allows an RMI compass card to be controlled by the HSI. "

Do those digital HSIs and AIs found in a Boeing 737, Boeing 747 or in a Bombardier Learjet also have a gyro like a normal HSI? They do, right? But they only display the information on a screen. It's weird that no gyro spinning is heard after switching the battery on.

The glass panel HSIs and ADIs (like the airliner and business jets you've mentioned) usually use a ring laser gyro, or something similar to sense rotations.
http://en.wikipedia.org/wiki/Ring_laser_gyroscope