VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #31  
Old 11-11-2010, 12:51 PM
Flying Scotsman Flying Scotsman is offline
 
Join Date: Nov 2005
Posts: 1,256
Default

I'll go ahead and pick up the last couple of posts and include them in a post on a new thread over in Safety...how's that?

ETA: Done...see new thread here:
http://www.vansairforce.com/communit...ad.php?t=64800
__________________
Steve "Flying Scotsman"
Santa Clarita, CA
PP-ASEL, ASES, Instrument Airplane

RV-7A N660WS flying!
#8,000

Last edited by Flying Scotsman : 11-11-2010 at 01:07 PM.
Reply With Quote
  #32  
Old 11-12-2010, 01:15 PM
penguin penguin is offline
 
Join Date: Jan 2005
Location: England
Posts: 1,087
Default

Quote:
Originally Posted by N941WR View Post
There are a LOT of advantages to having an integrated AP. Enough so that I think I like the idea of my AP knowing if I'm upside-down, in an unusual attitude, etc.

Imagine if you would, you get the plane upside down and then try to engage the AP. As the plane starts to loose altitude, a standard AP MIGHT just pull back on the elevator, causing a split-S. However, an AP that knows you are upside down MIGHT not do that. It MIGHT roll you right-side up before recapturing the proper altitude.

I'm not saying that any particular EFIS/AP combo will do this but just imagine if you designed an integrated EFIS/AP, how would you code it?

As Bob said, ?you?ll need to decide for yourself.?
Bill,

With respect, I wonder if you are the same issue? Any autopilot must know the attitude of the airplane to properly perform its task. The best gyros to do that are those specifically designed for the task - eg those fitted to a standalone (but linked up) autopilot. The gyros in an EFIS are designed to provide you with information to control the airplane. The two tasks are different. They might sound very similar, but are not, and require the gyros to be optimised in different ways (or probably the software that interprets the outputs from thegyro pack to be optimised in different ways). To be very useful the AP needs to be hooked up to the EFIS to receive nav requests - so linked to the EFIS yes, integrated with (and using the same gyros as), no.

Pete
Reply With Quote
  #33  
Old 11-12-2010, 03:27 PM
dynonsupport's Avatar
dynonsupport dynonsupport is offline
 
Join Date: Jun 2005
Location: Woodinville, WA
Posts: 1,499
Default

An autopilot need not know the attitude of the plane at all. It's totally possible to make an autopilot with just a turn rate gyro and an altimeter. It would have no idea if you were upside down or doing a flat turn with the rudder.

The goal of an autopilot is to hit a heading (track) and an altitude. All it needs to know if you are left or right of your heading and above or below your altitude. It doesn't need to care how you get there as long as the error is zero.

Of course, if it doesn't have EFIS data, it can't limit pitch or roll angles, and if it's upside down, it will do the "wrong" thing. But in normal conditions it should be able to fly the plane just fine.

None of this is meant to be an argument for or against an EFIS integrated AP, but call up Trio or TruTrak and ask them if their autopilot ever has any idea if your plane is upside down, and they'll tell you no, the AP doesn't need to know attitude to fly an airplane. Clearly you can make an excellent AP without knowing attitude since they both do it.

What is interesting to consider is what your "standalone" AP really needs to keep working. How long can it hold a heading and altitude with NO external connections? Does it need GPS to work? If it needs external data like a GPS to perform, and your EFIS is a GPS and PFD in one box, then do you consider yourself to have redundancy? Can it be power cycled in flight and still perform? Does it know when a servo has failed?
__________________
_______________________
Dynon Avionics
support@dynonavionics.com
425-402-0433
www.DynonAvionics.com
Reply With Quote
  #34  
Old 11-12-2010, 03:40 PM
Mike S's Avatar
Mike S Mike S is online now
Senior Curmudgeon
 
Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
Default

Good info Dynon, thanks for clearing things up a bit.
__________________
Mike Starkey
VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
Reply With Quote
  #35  
Old 11-14-2010, 02:06 AM
penguin penguin is offline
 
Join Date: Jan 2005
Location: England
Posts: 1,087
Default

Quote:
Originally Posted by dynonsupport View Post
An autopilot need not know the attitude of the plane at all. It's totally possible to make an autopilot with just a turn rate gyro and an altimeter. It would have no idea if you were upside down or doing a flat turn with the rudder.

The goal of an autopilot is to hit a heading (track) and an altitude. All it needs to know if you are left or right of your heading and above or below your altitude. It doesn't need to care how you get there as long as the error is zero.

Of course, if it doesn't have EFIS data, it can't limit pitch or roll angles, and if it's upside down, it will do the "wrong" thing. But in normal conditions it should be able to fly the plane just fine.

None of this is meant to be an argument for or against an EFIS integrated AP, but call up Trio or TruTrak and ask them if their autopilot ever has any idea if your plane is upside down, and they'll tell you no, the AP doesn't need to know attitude to fly an airplane. Clearly you can make an excellent AP without knowing attitude since they both do it.
Of course you are correct that a rate gyro based autopilot is possible and will work adequately (S-Tec did it for years), but why would you not want to know? It will provide much better performance in both axes.

Pete
Reply With Quote
  #36  
Old 11-15-2010, 09:50 PM
jeff beckley jeff beckley is offline
 
Join Date: Jan 2006
Posts: 192
Default

Denok. I will try to get this thread back on track..
Sorry about your BM. I too had a G4 lite plus with AP. I loved the design and UI. I looked at GRT and Advanced but settled on Trutrack EFIS with the AP4.
I liked the simple but Very powerful user interface over the fore mentioned.
Coming from BM you can understand.
While the TT EFIS does not have synthetic vision I found I really did not have much of a need for it and I really had no need for the complex interface the others have to offer.
I defined my mission as needing a Rock Solid AP, A EFIS that displayed the necessary information required for safe and reliable IFR flight, And a system that did not need a book to operate especially when **** hits the fan in IMC.
Every command on the TT is just one button press. One button for ILS coupling. One button press for GPSS approach, One button for simple wings level and alt hold. No sub menus to get lost in.
All the procedure approaches that it does are silky smooth even in the rough stuff.
The screen is uncluttered and easy to read with just a glance and has everything you need for IFR. Integration with the 430W is flawless.
My system with the AP4 is in every way the same as the sorcerer with a EFIS as its control head.
This is just a suggestion as you might have different missions from me.
I just did not want a display that had more bling bling than my mind could wrap around.
Also I trust the TT EFIS in IMC more than I trust myself.....


PS I will extend an offer to fly my RV7 if you are ever in iowa. "KIKV" You should try b4 you buy. Where are you located?
__________________
Jeff Beckley
Des Moines Iowa
Van's RV-7A

Last edited by jeff beckley : 11-15-2010 at 09:56 PM.
Reply With Quote
  #37  
Old 11-16-2010, 01:26 AM
Rainier Lamers Rainier Lamers is offline
 
Join Date: May 2007
Location: Somerset West
Posts: 1,033
Default

Just another comment on AP if I may (since it has been mentioned).
Yes, it is possible to make an AP with a single axis rate gyro (usualy mounted at a 45 degree angle so it measures both yaw and bank rates - but can't tell the difference) and a pressure sensor for the altitude.

But it can go further as well. An AP that has the "full picture" so to speak would be able to level your aircraft from any attitude provided the algorithms are written to recognise the attitude and know how to correct.

Those that our flying our AP can engage at any attitude and the AP will try to get you straight and level. This works slightly better with the MGL servos than the Trio servos (when connected to our AP) as they can respond faster.

You can see the effect without trying it on a real aircraft if you fire up our EFIS simulator and connect it to Microsoft Flightsim. Once you have everything setup and the AP dailed in (select the Trio servos for this, they are "faked" for the Flightsim interface), simply place the aircraft (I like the Baron, it seems to work fairly realistically) in any attitude you can think of and engage the AP - then sit back and watch...

I'm not saying this has realistic value - this is not the function of a traditional autopilot system which is more a flight path stabilization system than anything else. But it's fun anyway and why not ?

Rainier
CEO MGL Avionics
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 08:07 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.