PDA

View Full Version : AlTrak Question


Ironflight
04-17-2006, 06:37 PM
I'm hoping to get my new Altrak installed in the -8 this week, and have a very specific question for folks who are flying with one. Did you plumb the static source in to your static system, or just leave it open to the cabin? Since it is just a "relative" system (it doesn't know or care what the altitude is, just whether or not is is changing...), I'm inclined to think it doesn't make a difference. If I was opening and closing the canopy in flight, maybe - but I ain't gonna try that! So is anyone running it without plumbing, and how does it work?

Reason to ask? I hate to break into a certified static system that has no leaks....

Paul

kevinh
04-17-2006, 06:44 PM
I'm hoping to get my new Altrak installed in the -8 this week, and have a very specific question for folks who are flying with one. Did you plumb the static source in to your static system, or just leave it open to the cabin? Since it is just a "relative" system (it doesn't know or care what the altitude is, just whether or not is is changing...), I'm inclined to think it doesn't make a difference. If I was opening and closing the canopy in flight, maybe - but I ain't gonna try that! So is anyone running it without plumbing, and how does it work?


I plumbed mine into my static system - but the plane was not flying yet. However, I did use quick connects at one point in the static system and did a bit of exerimenting during my phase one. When opened to the cockpit air, the altrack worked fine - but opening and closing the vents would cause about 60 feet of vertical movement. ;-)

Ironflight
04-17-2006, 07:20 PM
- but opening and closing the vents would cause about 60 feet of vertical movement. ;-)


Of course! I hadn't thought about vents - I adjust mine all the time....guess I'll plumb to the static system...

Paul

DeltaRomeo
04-17-2006, 07:29 PM
Paul, my was plumbed in, but then the T-connector on the VSI broke and I flew it like that for a few days.

Opening and closing the vents doesn't cause my plane to go up/down by more than a foot (just a slight burble, feels like turbulence, when I open/close the vent).

I'd leave it open! Easier....


b,d

SteinAir
04-17-2006, 08:16 PM
As a whole, you'll end up fine just leaving it vented to the cockpit. Most of the time the "brain box" is installed behind the baggage compartment bulkhead where the pressure is relatively static anyway. Of course, the vents can cause a slight change, but as stated usually nothing major or even noticeable. I have mine in my -6 plumed to the static line, but only because it was really easy and handy to do. If it wasn't, I wouldn't hesitate to leave it vented to the open empennage.

Just my 2 cents as usual.

Cheers,
Stein.

kevinh
04-17-2006, 08:32 PM
As a whole, you'll end up fine just leaving it vented to the cockpit. Most of the time the "brain box" is installed behind the baggage compartment bulkhead where the pressure is relatively static anyway. Of course, the vents can cause a slight change, but as stated usually nothing major or even noticeable. I have mine in my -6 plumed to the static line, but only because it was really easy and handy to do. If it wasn't, I wouldn't hesitate to leave it vented to the open empennage.


Wow - that's so strange. I'll play with my static bypass again this weekend. I wonder if it's because my altrack is up behind the panel.

SteinAir
04-17-2006, 09:51 PM
Wow - that's so strange. I'll play with my static bypass again this weekend. I wonder if it's because my altrack is up behind the panel.

Just curious....but are you saying you have the little brain box up behind the panel then run the group of wires all the way back to the bellcrank and servo?

If so, I'm just a bit curious as to why? TruTrak normally wants the "box" pretty close to the servo back near the elevator bellcrank, and the only thing on or behind the panel is normally the switch and/or the VS button.

Not flaming you, just curious...as that's not a very standard install in my experience.

Cheers,
Stein.

Ironflight
04-17-2006, 10:02 PM
Stein,

I was actually planning on mounting my "brain box" up on the panel as well...kind of collocated with the Pictorial Pilot. I really hadn't thought about putting it aft with the servo. I guess I just always think about puting the "avionics" in the panel. See...sometimes it is hard to think outside of the box! I guess I'll think about the wire runs and see what's easier.

Paul

szicree
04-17-2006, 10:04 PM
I don't know a thing about the Altrak, but I did have an interesting thing happen while plumbing my Trutrak ADI. The installation manual said that plumbing to the static port was not needed except in pressurized aircraft. What the manual failed to mention is that if you do choose to plumb to the static port your system will leak like a sieve through the instrument. Apparently there is some leak built right into the device that they don't close up unless the instrument will be used in a pressurized aircraft. I only learned this after hunting for the source of the leak and finally calling Trutrak, who by the way were super helpful.

sprucemoose
04-18-2006, 01:58 AM
I installed mine originally just vented to cabin air (controller mounted behind the baggage bulkhead, per plans.) Opening/ closing the vents would cause the plane to jump up/down at least 50 ft. Plumbing into the static lines (a piece of cake, since they're right there) cured that.

And I have foam sealing all the trianlge-shaped holes on the baggage bulkhead, in an attempt to seal against leaks. Still makes a big (enough) pressure difference.

rv8ch
04-18-2006, 02:03 AM
And I have foam sealing all the trianlge-shaped holes on the baggage bulkhead, in an attempt to seal against leaks. Still makes a big (enough) pressure difference.I'll bet that's the difference. People who don't see a large altitude swing when they open and close the vents probably have less canopy and cabin sealing than those that do see a large altitude delta.

Usually, when you use the alt hold, you are in cruise flight, so probably won't be opening and closing the vents too much. However, passengers tend to want to adjust the vents a lot more, I've noticed. Perhaps they just need to have something to do! :)

BTW, if you plan to use some of the more advanced features, like Vertical Speed select, and altitude pre-select, it seems like it would be a good idea to plumb to the static system, just for more consistent operation. Not sure if these are available as upgrades to the trutrak. I'm going with the Trio, and it will have this, according to their website.

sprucemoose
04-18-2006, 02:06 AM
That's what was puzzleing. The baggage bulkhead is sealed so that no air can get from the tailcone (where the sensor and servo are) to the pax compartment. I would think that would prevent, not exacerbate, the problem. Show what I know.

In any event, the Altrak is a great addition to any RV. I installed mine just prior to the SnF trip last year, and boy was it worth it.

Ironflight
04-18-2006, 06:43 AM
OK guys, thanks again for all the input! I installed this in my minds eye several times last night while trying to sleep, and I think I'll go with Stein's idea of the brain box in back, and leaving the static port open (for now) - becasue it will be easy to cut it into the static system later once I see how it performs. It sounds to me like it is very aircraft specific, and I might get lucky!

This just proves again how all the help available on the 'net helps people build better - and faster! (and yes, my builder's log is still open...)

Off to the airport!

Paul

frankh
11-05-2006, 07:48 PM
Hi Paul.

I too mounted my box next to the servo (as I had only run 7 wires back there instead of the required 8...Doh!). Anyway putting the box next to the servo means you only need 4 wires running back...cool!

I was about to cut my static line but would rather not...How did yours work out without plumbing into the static, with the box in the tailcone??

I was bout to go fly it when the lighted switch disintergated....Looks like it should have had some glue to hold it together but mine didn't and now its toast...OH well.


Thanks

Frank

Ironflight
11-05-2006, 08:34 PM
Frank - I've got probably a hundred hours with it so far, and it's worked perfectly - until you resurrected this thread, I had forgotten that I never tied it into Static.... ;)

Paul

sjhurlbut
11-06-2006, 08:21 AM
Mine is not connected to the static system and works perfectly. Put the control box right beside the servo on the bellcrank. 5 inch long wire connections are better. And use the shielded wire as described in the manual. My altrak hummed a bit until I changed to shielded wire.

Steve
RV7A
70 hrs

frankh
11-06-2006, 09:18 AM
learn to actually read the manual.

I did not see anything about a sheilded wire...So what wire are we talking about exactly?

Frank

rickmellor
11-06-2006, 08:09 PM
Just curious....but are you saying you have the little brain box up behind the panel then run the group of wires all the way back to the bellcrank and servo?

If so, I'm just a bit curious as to why? TruTrak normally wants the "box" pretty close to the servo back near the elevator bellcrank, and the only thing on or behind the panel is normally the switch and/or the VS button.

Not flaming you, just curious...as that's not a very standard install in my experience.

Cheers,
Stein.

I was planning to install my brain box in the panel like Kevin has it. The thought was that if I ever wanted to upgrade from the Pictorial Pilot/Altrak VS to a single unit then the wires would already all be at the panel.

-Rick

rscott5559A
11-07-2006, 10:42 AM
I took this from the install manual. Don't see where it states the brain needs to be by the servo...

Mounting the programmer module of the Altrak can be done in any location; the only requirement that must be met is that the side of the unit label "This side right" must face the right side of the aircraft. The rotational position is not important as long as the right side is facing right. The side with the sticker also must be parallel with the direction of flight (see attached drawing for more information).


Just curious....but are you saying you have the little brain box up behind the panel then run the group of wires all the way back to the bellcrank and servo?

If so, I'm just a bit curious as to why? TruTrak normally wants the "box" pretty close to the servo back near the elevator bellcrank, and the only thing on or behind the panel is normally the switch and/or the VS button.

Not flaming you, just curious...as that's not a very standard install in my experience.

Cheers,
Stein.

Doyce Graham
11-07-2006, 02:53 PM
Paul, Two data points. Did not hook AlTrak to pitot system with two airplanes and same AlTrak. No real problems and very little change in altitue with vent open/close. Excellent product for my part. Mounted behind baggage wall as per suggested by True Trak.

Doyce Graham