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cjensen
05-17-2008, 12:24 PM
Is it possible to install only the TT Altrack pitch servo, set altitude hold, and hand fly navigation?

I'm wondering for two reasons...one is MGL is now offering servos that interface with the EFIS systems they offer, but AH isn't available yet.

Two, I want AH but may not want roll servo's at all...

:confused:

Radomir
05-17-2008, 02:04 PM
Sure... can't think of a reason why not.. more or less same as having wing leveler and having to keep the altitude "by hand"

Having both is best, though :)

cjensen
05-17-2008, 02:36 PM
Okay...so Altrack alone WILL NOT hold altitude? I thought that's what Altrack was...??? The pitch servo controlling the elevator would be the one to hold altitude. A wing leveler would be a roll servo only.

I'm wanting to know if one could buy just the pitch servo, and the green ALT button to hold altitude without an AP head like the ADI II...

Radomir
05-17-2008, 03:56 PM
I didn't say that... not sure where you're reading it :) I'm saying there's no problem having only one axis autopilot.. whichever axis it is...

yes, you can buy Altrack alone w/o having the other axis.

Sam Buchanan
05-17-2008, 03:56 PM
Okay...so Altrack alone WILL NOT hold altitude? I thought that's what Altrack was...??? The pitch servo controlling the elevator would be the one to hold altitude. A wing leveler would be a roll servo only.

I'm wanting to know if one could buy just the pitch servo, and the green ALT button to hold altitude without an AP head like the ADI II...

Absolutely. The AlTrak is totally independent of any other system and will happily hold altitude as long as you have the green button pushed in. You can lock in altitude and still navigate as you wish, either by hand or via some other tracking system. The AlTrak consists of the servo, a control box (most folks mount it next to the servo) and the switch.

The AlTrak installation in my RV-6 before an upgrade to the Trio EZ-Hold-3:

http://thervjournal.com/altrak.htm

cjensen
05-17-2008, 04:06 PM
Thanks guys! That all makes sense now...:cool:

nucleus
05-17-2008, 05:43 PM
Chad, you want the roll control to keep your wings level... This is where most autopilots start. Then the 2nd axis is pitch... I have never since one with just pitch control.

Hans

David-aviator
05-17-2008, 06:09 PM
Is it possible to install only the TT Altrack pitch servo, set altitude hold, and hand fly navigation?

I'm wondering for two reasons...one is MGL is now offering servos that interface with the EFIS systems they offer, but AH isn't available yet.

Two, I want AH but may not want roll servo's at all...

:confused:

Chad,

I've been flying with Altrack altitude hold for 4 years. It works great with or without the Navaid Devices wing leveler on. This is the unit from Van's. It comes with one servo, the pitch servo.

http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1210992750-206-309&browse=fi&product=altrak

DeltaRomeo
05-17-2008, 06:21 PM
Thanks guys! That all makes sense now...:cool:

Chad!

My prefered way to travel is just as you are wanting - altitude hold on with me doing the left/right steering. It's very, very useful for turning the plane just a tad to see something on the ground (and not having to worry about fighting a roll servo).

If I had to pick one servo to keep, it would be pitch, btw!

I used it today, as a matter of fact <g>. You're gonna love it!

b,
d

flyeyes
05-17-2008, 06:35 PM
Chad!

My prefered way to travel is just as you are wanting - altitude hold on with me doing the left/right steering. (snip)

Doug, I've never flown with an autopilot that would engage alt hold only, but one thing concerns me.

What happens with a roll upset? It seems that if the airplane banks, the nose will drop a little, which causes the pitch servo to pull back a little, which can increase the bank angle. This could become a positive-feedback loop ending in a high-g, high speed spiral dive.

I have always though (without any evidence) that this was why I've never seen a certified autopilot that would engage pitch without roll first. I suspect Kevin Horton could shed some light here...

cjensen
05-17-2008, 06:42 PM
Chad, you want the roll control to keep your wings level... This is where most autopilots start. Then the 2nd axis is pitch... I have never since one with just pitch control.

Hans

If I don't have roll control, is my airplane gonna fall out of the sky with me trying to do it!!??:eek: Just kidding Hans...;) I guess I'll be the first one you've seen then...:D

My airplane will be VFR only, and I want to be able to set the AH on a cross country, and navigate myself. This is strickly my opinion, but unless one flies a lot of IFR IN IMC, a full autopilot takes the fun out of flying. When I was flying a King Air 200, I would always hand fly it in VMC conditions...with the AH only engaged.:cool:

cjensen
05-17-2008, 06:46 PM
Chad,

I've been flying with Altrack altitude hold for 4 years. It works great with or without the Navaid Devices wing leveler on. This is the unit from Van's. It comes with one servo, the pitch servo.

http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1210992750-206-309&browse=fi&product=altrak
That's exactly what I'm looking at David, thanks!

Chad!

My prefered way to travel is just as you are wanting - altitude hold on with me doing the left/right steering. It's very, very useful for turning the plane just a tad to see something on the ground (and not having to worry about fighting a roll servo).

If I had to pick one servo to keep, it would be pitch, btw!

I used it today, as a matter of fact <g>. You're gonna love it!

b,
d
It's the way I fly a lot of airplanes with full AP's and AH...I just wanted to make sure I could get AH only, and have it work!

That's the way I intend to fly cross country too Doug!:D

Sam Buchanan
05-17-2008, 07:19 PM
Doug, I've never flown with an autopilot that would engage alt hold only, but one thing concerns me.

What happens with a roll upset? It seems that if the airplane banks, the nose will drop a little, which causes the pitch servo to pull back a little, which can increase the bank angle. This could become a positive-feedback loop ending in a high-g, high speed spiral dive.

I have always though (without any evidence) that this was why I've never seen a certified autopilot that would engage pitch without roll first. I suspect Kevin Horton could shed some light here...

I'm not Doug (or Kevin), but I have flown four different autopilots in my RV-6, the AlTrak being one of them.

I'm not sure what you are referring to as a "roll upset". The scenario we are discussing is having pitch controlled with the AP and the pilot taking care of roll control. Maybe you are thinking about ops in IMC, but this discussion is concerning VMC flight.

Guess if the plane gets really out of whack (not sure how this happens in VMC) the pilot needs to disengage the pitch servo post haste. If that is done, the spiral dive thing wouldn't have a chance to develop, at least not due to the autopilot.

I've flown a lot of hours with just the AlTrak running and guess I've never considered losing the airplane due to having just pitch autopilot. The AlTrak doesn't fly aggressively enough to put the plane in a high-G environment. Put the plane into a 30 degree bank with the AlTrak running and it will allow the nose to fall through the horizon due to its very "soft" response. It may eventually be able to recover level flight in a significant bank but it would take quite a while. On second thought, I suspect the plane would be so deep into a dive if left alone the AlTrak would never be able to catch it.

The Trio EZ-Hold, on the other hand, can be easily calibrated by the pilot on-the-fly so that it can hold altitude very aggressively. However.......the designers very cleverly put an accelerometer in the Trio servo that will disengage the system if it sees an unusual G-load. I've seen the EZ-Hold disengage one time due to G-loading while coming out the back side of a whopper of a thermal. The G-meter on the Dynon registered 2.4G during that bump and the EZ-Hold disengaged just as designed. A simple push of the button and it was once again flying the plane.

cjensen
05-17-2008, 08:27 PM
I have always though (without any evidence) that this was why I've never seen a certified autopilot that would engage pitch without roll first.
I don't mean to repeat myself from a previous post, but in the King Air 200 I used to fly, I would routinely fly it with just the AH engaged, and hand fly/navigate the thing at all altitudes.

:)

flyeyes
05-17-2008, 08:41 PM
I don't mean to repeat myself from a previous post, but in the King Air 200 I used to fly, I would routinely fly it with just the AH engaged, and hand fly/navigate the thing at all altitudes.

:)

I've learned something ;-)

I've flown a B-200 (with a Sperry autopilot IIRC) a little but it was years ago and I never had a thorough checkout. I didn't know it could do that.

The APs I've learned thoroughly have been various S-TECs, Century, and Cessna Nav-O-Matic. My wife called the Nav-O-Matic "Winnie the Pooh" because it was the autopilot with very little brains.

videobobk
05-17-2008, 08:50 PM
Chad, I agree. AH is very handy, even when hand flying. At the end of a X-C, I often dial in a -400fpm in order to get down to traffic pattern altitude while hand flying to arrive on whatever side of the airport I need to be on. Very handy and saves stress on the ears from letting down too fast.

I'm not that far away if you would like to try your hand at the trio combination. I also agree you should consider the roll servo. Saves lots of effort on X-C work. The RV may not be quite as stable as the King Air! 'Course I never flew a King Air....

Bob Kelly at OVO

cjensen
05-17-2008, 09:28 PM
My wife called the Nav-O-Matic "Winnie the Pooh" because it was the autopilot with very little brains.
HA! Now THAT is funny!!:D

I'm not that far away if you would like to try your hand at the trio combination. I also agree you should consider the roll servo. Saves lots of effort on X-C work. The RV may not be quite as stable as the King Air! 'Course I never flew a King Air....

Bob Kelly at OVO
I'd love to do that if I get down your way Bob! I already have the pitch servo mount installed in my 7, which is the only reason I refer to the Altrak...I'd consider the Trio if it's better, and won't interfere with the bracket that's already mounted...

RV's are WAY less stable than a King Air...the KA is about as stable an airplane as one can get. Even on one engine, it's a pussy cat...though one leg can get tired. I'm getting off the subject here...I may very well do a full AP, but if I can get started with pitch/AH, I'll do that. I already have the pitch servo mount installed from TT as well. I just don't know if I want to pay for the full ADI boat.

I actually like the effort in X/C trips...puts the flying in flying.:D

frankh
05-18-2008, 08:16 AM
a pictorial pilot and an Altrak...ANd I actually like the fact that the two A/P's are distinctly seperated.

Often in IFR will make turns with just the AH engaged and it works just fine.

The main reason I do this is the PP only makes turns at about half standard rate which is irritating but i have not found how to up the bank angle on the PP.

Frank

TrutrakTech
05-19-2008, 10:34 AM
I'm not Doug (or Kevin), but I have flown four different autopilots in my RV-6, the AlTrak being one of them.

I'm not sure what you are referring to as a "roll upset". The scenario we are discussing is having pitch controlled with the AP and the pilot taking care of roll control. Maybe you are thinking about ops in IMC, but this discussion is concerning VMC flight.

Guess if the plane gets really out of whack (not sure how this happens in VMC) the pilot needs to disengage the pitch servo post haste. If that is done, the spiral dive thing wouldn't have a chance to develop, at least not due to the autopilot.

I've flown a lot of hours with just the AlTrak running and guess I've never considered losing the airplane due to having just pitch autopilot. The AlTrak doesn't fly aggressively enough to put the plane in a high-G environment. Put the plane into a 30 degree bank with the AlTrak running and it will allow the nose to fall through the horizon due to its very "soft" response. It may eventually be able to recover level flight in a significant bank but it would take quite a while. On second thought, I suspect the plane would be so deep into a dive if left alone the AlTrak would never be able to catch it.

The Trio EZ-Hold, on the other hand, can be easily calibrated by the pilot on-the-fly so that it can hold altitude very aggressively. However.......the designers very cleverly put an accelerometer in the Trio servo that will disengage the system if it sees an unusual G-load. I've seen the EZ-Hold disengage one time due to G-loading while coming out the back side of a whopper of a thermal. The G-meter on the Dynon registered 2.4G during that bump and the EZ-Hold disengaged just as designed. A simple push of the button and it was once again flying the plane.

Sam, you can increase the activity level of the Altrak by applying 12 volts to pin 10 of the Altrak module. This will increase the "sensitivity" by making the servo move faster. If you are pleased with the current performance of the unit, I would suggest leaving it as is (I assume at the neutral or medium setting, no connection to pin 10), as the increased activity may cause a slight bounce in level flight in light turbulence. Thanks!

Sam Buchanan
05-19-2008, 01:47 PM
Sam, you can increase the activity level of the Altrak by applying 12 volts to pin 10 of the Altrak module. This will increase the "sensitivity" by making the servo move faster. If you are pleased with the current performance of the unit, I would suggest leaving it as is (I assume at the neutral or medium setting, no connection to pin 10), as the increased activity may cause a slight bounce in level flight in light turbulence. Thanks!

Yes, Lucas, I found the default setting to work fine for "normal" flying. I was aware of the other setting but never felt the need to use it. The "soft" setting is very comfortable even though it lets the altitude vary a little in turbulence.