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PostPosted: Fri Mar 17, 2017 3:53 am 
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Joined: Fri Dec 23, 2016 3:28 am
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I have touched on this before but post update the Sperry AP is still a headache to use. The pitch control (for me) is still too coarse (incrementally) as I still can't get it to settle into a nice groove where it's not climbing or descending. Insofar as the way the AP reacts to heading change inputs (the tendency to climb after heading change) may be how the original Sperry AP may have been but if only one of the two pilots were handling both the pitch and heading change, they'd need both hands on those control knobs to keep the aircraft stable from pitching up. The problem with this behavior being modeled in this model is that the mouse function is tied up doing one or the other input at one time and you have to do a dance of sorts between the two controls to fight to keep the plane on altitude through the turn. As I suggested before, it would be of great benefit to add a "smart aircrew" function which allows the user to use the heading change control and the FO to control the pitch to keep it stable in the turn. To be very honest, at current (for me) using the Sperry A/P make flying this model downright un-enjoyable for trying to fly vintage flight routine flows. I mostly use the FS A/P (which is still limited to 18,000ft with this model due to porpoising issues).


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PostPosted: Fri Mar 17, 2017 4:28 am 
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Master Sergeant

Joined: Tue Mar 15, 2016 8:23 am
Posts: 1349
Hi.
The 2d auto pilot popup can control the connie at alts upto 24000ft at a stable pitch , if you are not able to do this , then look at your weight and balance prior to takeoff , as you maybe to heavy for that alt at that time , and need to do step climbs if heavy while fuel is burned off .
I use the sperry on my online flights , and yes it is a juggling act during turns , trim for 100/200fpm nose down just prior to turnning , and do large turns in smaller doses , to limit climb tendancies , once turn completed retrim for level flight , its all a matter of practice , keep at it , and you will start to enjoy this little gem more and more .
regards alan. 8) :lol:

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PostPosted: Fri Mar 17, 2017 2:02 pm 
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Joined: Tue Oct 29, 2013 9:08 pm
Posts: 87
Location: KSEE
This may be a radical idea, but if you're going to have your hands full anyway, how about:

Disengage the autopilot
HAND fly the turn
Reengage the AP on the new heading.

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Cub, Spit, P-51 Civ, 172, 180, Comanche, T-6, Connie.


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PostPosted: Fri Mar 17, 2017 2:44 pm 
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Airman

Joined: Fri Dec 23, 2016 3:28 am
Posts: 12
Quote:
This may be a radical idea, but if you're going to have your hands full anyway, how about:

Disengage the autopilot
HAND fly the turn
Reengage the AP on the new heading.


Yes, in general that's about the only way to make a stable turn with the coding of the Sperry A/P on this model. The only retired Pilot I knew (who's long since been deceased) who flew the old C-69 and later C-121 told me they rarely to never used the A/P during maneuvering, climbs and descents, all hand flying unless they were flying straight and level, then they'd use the pitch hold to reduce the workload. I have heard and read the same thing from a number of other Connie Pilots over the years.

Anyhow, as I mentioned before, the one issue with the Sperry A/P coding that makes it nearly unusable for me is the fact I cannot get it to hold altitude, it's either a hair too much up or down regardless of fine tuning the trim. The issue is simply that the adjustments are still too coarse. If that issue could be fixed, I'd use the Sperry 100% of the time and hand fly the turns, ascents, and descents and not even fool with it for maneuvering.

As far as the 2D FS autopilot, even with low weight (moderate fuel and passenger/cargo weights), at target airspeeds and a 500fpm climb (yes, in stepped climbs if necessary), I am still encountering the porpoising (mild pitch oscillations) if flying above Fl 180. Oddly this issue does not occur when using the Sperry A/P. Bottom line, there's a bug or two here, not a weight and balance issue nor me attempting to fly the model out of performance parameters thus inducing the mild pitch oscillations during level-off over FL180. I am a Licensed Pilot and have been since 1990 and I know full well about performance & weight and balance limitations of any aircraft I've trained on to fly. ;)


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PostPosted: Fri Mar 17, 2017 3:00 pm 
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A2A Master Mechanic
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Location: San Francisco
I use a combination of the AP elevator control setting and a bit of the elevator trim to
set my desired altitude.

Prior to a turn I give the AP elevator control 2 or 3 'clicks' down (mapped to a switch)
and then 2 or 3 clicks up as I complete the turn. As Alan suggested, it is a matter of practice
regardless of the method you use.

Paul

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PostPosted: Fri Mar 17, 2017 3:56 pm 
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Airman

Joined: Sun Mar 12, 2017 10:33 pm
Posts: 39
Interesting. I've completed half of a 1,200 mile island hop with this bird (that I hope to finish this weekend), at FL200. I was using the FS autopilot for altitude hold so I could play navigator instead of fly. I think i weighed around 78,000lbs when reaching cruise, and she never porpoised at all for almost 3 hours. Rock steady, even in turbulence.


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PostPosted: Fri Mar 17, 2017 4:35 pm 
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Airman

Joined: Fri Dec 23, 2016 3:28 am
Posts: 12
Quote:
Interesting. I've completed half of a 1,200 mile island hop with this bird (that I hope to finish this weekend), at FL200. I was using the FS autopilot for altitude hold so I could play navigator instead of fly. I think i weighed around 78,000lbs when reaching cruise, and she never porpoised at all for almost 3 hours. Rock steady, even in turbulence.


Yes I agree, not sure what to make of the issue I am having as I'm well below that weight and still seeing the pitch osculations (using the FS A/P) at about FL180. At this point I'm used to flying at that cruise level and being happy with it.

Quote:
I use a combination of the AP elevator control setting and a bit of the elevator trim to
set my desired altitude.

Prior to a turn I give the AP elevator control 2 or 3 'clicks' down (mapped to a switch)
and then 2 or 3 clicks up as I complete the turn. As Alan suggested, it is a matter of practice
regardless of the method you use.


I understand the methodology but my point is that any given user's control hardware interface & settings may have different values/sensitivities which in my case may be the reason it's so difficult to tune the Sperry A/P into a groove that lowers the workload. As it stands, I have about 200+ hours flying the model and a good bit of that was trying to work with the Sperry (to no avail) so it's safe to say I have plenty of practice.

It's okay, I understand that "vintage equipment" quirk coding is something most Devs get defensive about when questions are brought up regarding individual user difficulties with using certain functions (I know this well as I work for another major development team) but nonetheless, my advice is to not ignore even the minority of users who are experiencing either difficulties or anomalies with such features/coding by constantly pushing the standard narrative of "just practice, you'll get the hang of it" when there is a technical issue the user is having difficulty. No offense intended, I've been doing this (flight sims) a long time.


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PostPosted: Fri Mar 17, 2017 5:35 pm 
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Joined: Tue Oct 29, 2013 9:08 pm
Posts: 87
Location: KSEE
You might try tweaking the power to "fine tune" the altitude hold.

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Cub, Spit, P-51 Civ, 172, 180, Comanche, T-6, Connie.


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PostPosted: Fri Mar 17, 2017 6:19 pm 
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A2A Master Mechanic
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Joined: Wed Dec 29, 2004 6:28 pm
Posts: 4801
Location: Florida
Gypsy Baron wrote:
I use a combination of the AP elevator control setting and a bit of the elevator trim to
set my desired altitude.

Prior to a turn I give the AP elevator control 2 or 3 'clicks' down (mapped to a switch)
and then 2 or 3 clicks up as I complete the turn. As Alan suggested, it is a matter of practice
regardless of the method you use.

Paul

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That's the method I've been using also, mapped to a hat switch.


Forest

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PostPosted: Fri Apr 14, 2017 2:49 pm 
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Joined: Thu Apr 01, 2010 11:17 pm
Posts: 349
Location: West Texas
ratty wrote:
This may be a radical idea, but if you're going to have your hands full anyway, how about:

Disengage the autopilot
HAND fly the turn
Reengage the AP on the new heading.


Actually, you don't even have to disengage the aileron or rudder just the elevator, I disengage the elevator, make the turn and then just reengage the elevator. Control pitch with the yoke and trim wheel during the turn, easy.

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Thanks Mark


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PostPosted: Fri Apr 14, 2017 2:59 pm 
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Master Sergeant

Joined: Tue Nov 05, 2013 10:48 am
Posts: 1161
Location: Oksbøl, Denmark
I don't use the Sperry Autopilot but as I understand it you should be able to use the throttle to fine tune the aircraft. If the Sperry hold the aircraft in an attitude the power setting would decide whether the aircraft is flying level or climbing/descending. On the other A2A aircraft this is a good way to "trim " it

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Tomas

Accu-Sim aircraft in my hangar:
C172, C182, P51 Civ, P51 Mil, B17, Spitfire, P47, B377 COTS, J3 Cub, T6, Connie


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PostPosted: Sat Apr 15, 2017 2:13 am 
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Joined: Wed Apr 07, 2010 6:13 am
Posts: 420
You shouldn't have to 'tweek' the power, after all the engines are set to certain MP RPM torque settings for the altitude.
Remember that increasing speed will cause the plane to increase lift and will climb, and the same with decreasing speed.
If the sperry is set to produce a vs of 100fpm climb it will slow down and settle into level flight. So let the plane climb through to just under the desired altitude, give it a down click to level out which you would think would make the plane sink again but as it increases speed slightly it settles into level flight. Give it a minute to settle and see what it does. If you are constantly chasing vs every 10 seconds of course it wont settle.
Similarly over the course of a flight as fuel burns off it will drift up 100-200 ft and a single down click or 2 will start descending the plane towards desired altitude but will increase speed will level out.

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Trev


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PostPosted: Thu Apr 20, 2017 6:33 pm 
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Joined: Mon Mar 03, 2008 12:06 pm
Posts: 1950
Location: Wichita Falls, Texas, USA
StormILM wrote:
I have touched on this before but post update the Sperry AP is still a headache to use. The pitch control (for me) is still too coarse (incrementally) as I still can't get it to settle into a nice groove where it's not climbing or descending. Insofar as the way the AP reacts to heading change inputs (the tendency to climb after heading change) may be how the original Sperry AP may have been but if only one of the two pilots were handling both the pitch and heading change, they'd need both hands on those control knobs to keep the aircraft stable from pitching up.


The way the real pilots did it was they only used the Sperry A/P for straight and level flight. There was no messing with the knobs with 4 hands. They simply disengaged the A/P, made the turn, then re-engaged the A/P. The real thing wasn't that great. It's why they were removed or replaced by better units as they became available. It was better than nothing though, so pilots dealt with it.

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