Jump to content

Sign in to follow this  
captain_adf

Pitch and roll cue - single or split axis?

Recommended Posts

Hey NGX pilots,

 

What are your thoughts/preferences for the pitch and roll cue on the display? Personally I tend to prefer the single cue. I find it easier to follow the flight director using the single cue because you can easily envision rolling the wings into shape. With the split axis, I never know what to do with the rudder.

 

Which is more popular? It seems the split axis is more "modern"? But I don't see why. Curious what others think.

 

Cheers!

Share this post


Link to post
Share on other sites

Hey NGX pilots,

 

What are your thoughts/preferences for the pitch and roll cue on the display? Personally I tend to prefer the single cue. I find it easier to follow the flight director using the single cue because you can easily envision rolling the wings into shape. With the split axis, I never know what to do with the rudder.

 

Which is more popular? It seems the split axis is more "modern"? But I don't see why. Curious what others think.

 

Cheers!

 

I prefer the dual cue format, mainly because that's what I look at all day.  Having used both I find the dual cue can be flown with more precision than the single cue.  It the end it simply a matter of personal preference as both types ultimately provide the same information.

 

As for what to do with the rudder?  With the exception of takeoffs, landings, and flying with an engine out you don't do much of anything with it.  As long as both engines are running you can fly the real airplane after takeoff with your feet flat on the floor and not notice much difference.  It's not like a light airplane where you need to correct for adverse yaw.

Share this post


Link to post
Share on other sites

 

 


As for what to do with the rudder? With the exception of takeoffs, landings, and flying with an engine out you don't do much of anything with it.

 

Thanks for that reminder to stay off the rudder, you've got that exactly right I forgot about that!

Share this post


Link to post
Share on other sites

Ditto Joe... and I'm not sure the split axis is more "modern" as it has been around since the earliest days of instrument flying.  The single cue was new to me in a 70s Flying Magazine article on flight directors (I think), not sure what its lineage is.  I am more comfortable with the dual needle.

Share this post


Link to post
Share on other sites

I've heard dual-cue can be more accurate. I'm not sure why.

 

The reason I'd prefer single-cue is it has a direct indication of the bank needed. eg. FD, "Hey, I need you to bank right  to 15 degrees, and I'm going to tilt the chicken lips to 15 degrees. Match that."

 

Dual-cue doesn't have that. eg. I want you to roll to the right some secret amount. Roll some more, more, a little more. . .there 15 degrees is perfect.

 

Dual-cue is better when you want to or need to ignore one axis either by disabling it (eg. CWS-P). I've "paralled" the single-cue when I wanted to do something (fly a dot high) but dual is better for that.

  • Upvote 1

Share this post


Link to post
Share on other sites

I think Matt described the essence of the difference between the two, besides there being one or two visual clues.  The dual cue provides attitude correction guidance, it says lift you nose a little more or bank a little more... or a lot more. The deviation is an indication of roll rate or pitch rate desired by the FD.  I did not realize that the single cue "chicken lips" presented the desired attitude.... I have to fly it a little to see how I might accommodate to it.

 

 Wrapping my head around this now.... so, if a standard right turn requiring 17 deg bank is desired by the FD the chicken lips will roll to 17 deg bank, and you roll as quickly or as slowly as you wish to get there.. the dual cue roll bar will command a specified roll rate to achieve 17 deg, the greater the roll rate commanded the greater the bars deflection.  Interesting.

Share this post


Link to post
Share on other sites

I think Matt described the essence of the difference between the two, besides there being one or two visual clues.  The dual cue provides attitude correction guidance, it says lift you nose a little more or bank a little more... or a lot more. The deviation is an indication of roll rate or pitch rate desired by the FD.  I did not realize that the single cue "chicken lips" presented the desired attitude.... I have to fly it a little to see how I might accommodate to it.

 

 Wrapping my head around this now.... so, if a standard right turn requiring 17 deg bank is desired by the FD the chicken lips will roll to 17 deg bank, and you roll as quickly or as slowly as you wish to get there.. the dual cue roll bar will command a specified roll rate to achieve 17 deg, the greater the roll rate commanded the greater the bars deflection.  Interesting.

 

I flew V-bars in the SF340 for a long time. I've never flown the 737 V-bars, so I'm extrapolating my info.

 

The SF340 F/D would present a required bank angle, but it would smoothly roll to the desired bank. This is the same as how the dual cue behaves in the 737, but the V-bar rolls to the bank angle required whereas the dual cue simply offsets and centers.

 

If the 737 single cue operates like I think it should, you should be able to check it by using HDG SEL and playing with the bank angle limit selector. You should see the selected limit reflected on the V-bar.

Share this post


Link to post
Share on other sites

I think it all comes down to presentation. I've flown them both. You find that most guys will stick to which ever one they grew up on. I started out with cross needles years ago in the C141B and transitioned over to single cue in the DC10. I flew the DC10 for years and now I'm a single cue guy. Guys will tell you that the cross hairs are more precise because the needles are thin and all you have to do is keep the point at the intersection. In my opinion, this is all appearance. You find that when hand flying, you are not always precisely glued to the flight director. There will be some slop and you generally work at keeping your reference in the general area because you are scanning other instruments to build the full picture instead of pure FD. Perfect example is the flight path vector in the HUD. In the Gulfstream, you find the flight path vector is constantly in motion moving around in a small area. To the pilot flying, you feel like you are all over the place, but looking at instruments, you are spot on. The flight path vector is definite and constantly making calculations based on what the jet is doing. You basically just keep your attitude ref inside the action to be precise. It's the same when it comes to the FD. I find that guys mostly fly in single cue because our jets default to it. There are times when I'm in single cue and the other guy is in cross pointer. Basically same difference.

Share this post


Link to post
Share on other sites

Interesting topic. I've read a lot on this and there's much diversity of opinions.

 

In my opinion it boils down to whatever representation you're most used to. Dual-cue (X-bars) seems to be much more common today than single-cue (V-bar). Single-cue seems to be easier to follow, dual-cue allows you to ignore one of the two axes.

 

I prefer dual-cue and that's the one I'm most used to.

Share this post


Link to post
Share on other sites

 

 


I started out with cross needles years ago in the C141B

 

Howdy... my first simulator ride was at McChord AFB in their Starlifter simulator somewhere around 1971-72.  An experience I'll never forget.

Share this post


Link to post
Share on other sites

 

 


Guys will tell you that the cross hairs are more precise because the needles are thin and all you have to do is keep the point at the intersection. In my opinion, this is all appearance. You find that when hand flying, you are not always precisely glued to the flight director.

 

Exactly! The needles are thinner, but I'm only looking at the edges. Like a thin ruler is more accurate than a thick ruler . . you're just using the edge. The pink pixels are next to the black, or they ain't.

 

I see the F/D as more of a suggestion. I fly like my granny is in the back and I don't follow either axis if it's going to make my ride jerky. I'm enough of a jerk already.

Share this post


Link to post
Share on other sites

 

 


I see the F/D as more of a suggestion.

 

Very much so.  More often then not I'll put the airplane into the attitude I know it needs to be in and let the flight director catch up with me.

Share this post


Link to post
Share on other sites

For realism I always use the setup for the livery I've chosen. However I prefer the spllt axis presentation. The vee bars command feels less precise to me although I know that in fact it is exactly the same.

Share this post


Link to post
Share on other sites

Howdy... my first simulator ride was at McChord AFB in their Starlifter simulator somewhere around 1971-72.  An experience I'll never forget.

Great!, the mighty starlifter(starlizard) took had me in some interesting places all around the world!

If you are splitting hairs and atoms to be precise when handflying, you are working too hard, doing it wrong and suffering from channelized attention.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...