Whisky compass near SV Classic D1000?

[SV_Classic]

Hi all,

I've got limited panel space and no real options other than to plop the whisky compass next to the front cockpit D1000. It'll be about six inches to the side of the D1000. Is it impractical to think the compass will be able to function being that close to the display unit?

Thanks,
Bart

 

[swatson999]

Why do you even need one? You have a magnetic direction indicator on the SV1000.

 

[airguy]

Agreed, no need for a whisky compass, you've got it on the screen.

 

[CanardMulti]

An alternative perspective: If installed as you propose, consider it as a backup instrument only. If your screen dies in flight, there wouldn't be any field to affect it if you pulled the breaker for the now useless screen. Placard the compass correction card as being applicable only with screen off. Would be interesting to perform two compass swings; one with screen powered and one with screen's breaker pulled to see just how much the compass is affected.

 

[SV_Classic]

Why do you even need one? You have a magnetic direction indicator on the SV1000.

Sorry I never replied, I was under the impression that the magnetometer was needed to make the DG function work but I guess not, good news.

Thanks

 

[swatson999]

Sorry I never replied, I was under the impression that the magnetometer was needed to make the DG function work but I guess not, good news.

Thanks

Ummmm...a magnetometer is different than the whiskey compass you first asked about. And yes, you *do* need a magnetometer...it's in the ADAHRS (Air Data and Attitude Heading Reference System).

What you *don't* need is a "wet" or "whiskey" compass in addition to the SV system. This has been hashed out repeatedly, but you may still run into the odd FSDO inspector or DAR who doesn't understand this, and will try to tell you that "you have to have a wet compass". That's incorrect. The ADAHRS meets the requirement for providing a "magnetic direction indicator" per the regulations.

 

[SV_Classic]

Sorry, a remote magnetometer, I didn’t realize the ADAHARS has a magnetometer built in. I know, ADAHARS includes direction but I just didn’t give it much thought since I’ll probably seldom use the attitude/direction display.

 

[swatson999]

It's in the manual.

I'm curious...you started out asking about wet compasses, but are now asking about the ADAHRS. Not trying to pick at you, but you seem a bit confused here. What exactly are you trying to sort out?

And how did you think an ADAHRS could give your direction if it *didn't* have a magnetometer?

The SV-ADAHRS-200/201 also incorporates an internal magnetic sensor (magnetometer). In this section, the more familiar term “compass” is often substituted for references to the magnetic sensor / magnetometer.
The SkyView SV-ADAHRS-200 (Figure 45) and SV-ADAHRS-201 (Figure 44) ADAHRS modules use MEMS sensor technology to accurately measure inertial, magnetic, and air data.

Installation Manual.

 

[CanardMulti]

Sorry, a remote magnetometer, I didn’t realize the ADAHARS has a magnetometer built in. I know, ADAHARS includes direction but I just didn’t give it much thought since I’ll probably seldom use the attitude/direction display.

Just to round out your understanding: The ADAHRS does indeed have a built in magnetometer. It also contains, among many other things, what amount to solid state gyros that serve several functions including that of an old school slaved directional gyro. If a particular installation finds it more sensible to mount it in a location that is subject to some form of magnetic disturbance such as nearby power lines or steel / iron structure or components, then the remote magnetometer can be added to the installation and mounted in a location free from such interference and its signal will be looked at by the system as the valid mag heading.

My plane is composite and both my primary and secondary ADAHRS are mounted with brass hardware under one of the back seats. The magnetometers work fine unless I forget and put my collapsible tow bar in the back seat instead of its usual stowage spot. In the back seat the steel towbar drives the system nuts.

Ken

 

[airguy]

Sorry, a remote magnetometer, I didn’t realize the ADAHARS has a magnetometer built in. I know, ADAHARS includes direction but I just didn’t give it much thought since I’ll probably seldom use the attitude/direction display.

So, what exactly do you intend to use to maintain navigational orientation? If you don't intend to actually use the display you are putting in the airplane, then why are you putting it in?

 

[SV_Classic]

Thanks for the replies. The plane I'm flying is going to be used 99.9% of the time to fly aerobatics so I'm not going to be looking at the attitude/heading displays very often. Flights will typically be to a local aerobatic practice area and back to the airport, lasting about .7 each.

I have been doing so much work to it the last eight months, I had just assumed I'd remount the compass and use it since it's all I really need. The Dynon screens are there because the original builder chose to install them and I plan to use them for traffic awareness and engine monitoring. I knew the Dynon could display magnetic heading but didn't realize the ADAHRS had the magnetometer built in, didn't really think about it with so much other stuff going on and I wasn't going to buy/install a remote magnetometer.

Appreciate the help.

 

[swatson999]

Traffic awareness doesn't do you much good if you have no heading or direction information, does it?

(You do have it, though, as you now know. Again, you should read the manuals so you know what your system does and, maybe more importantly, what it does not do).

 

[jnmeade]

Reading and understanding are sometimes legitimately two different things. I just assembled a 3-element 5-band HF antenna that I had to rebuild three times because the instructions were obtuse or missing. I use a radio logging program that is a marvel of capability but sometimes the instructions just don't seem to come across clearly. The author says feel free to ask questions.
Sometimes, it's a case of the person who designed the system writing the instruction manual. Guaranteed to be confusing. That person unthinkingly assumes the installer has information that is foreign to the poor guy building it. That happened to me putting outside stairs on a grain bin - the outer panels had slots in the bolt holes to compensate for the greater diameter while the inner ones did not. Obvious as soon as you thought about it, but not obvious if you'd never had occasion to erect one. It was hard to correct after you had the stair hanging on the outside of the bin.
Go ahead and ask questions. It is not such a good thing to ask others to do the basic research, though.