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mlwynn
07-28-2007, 12:57 PM
Hi folks,

I bought the servos and hardward to install both pitch and roll controls in my RV 8. I am getting close to final fuselage assembly and thought I ought prepare for installation as it would be easier to do before it all gets riveted together.

The installation manual from Tru-Track does not really discuss the servos. Their illustrations show the relationship between their mounting rails, the servos and the controls. It is fairly clear for the roll servo, but much less so for the pitch servo. They don't really give much indication as to where the mounting rails go. Specifically, in trying to install the elevator servo, do you cut away the part of the baggage floor that normally holds the elevator bellcrank? I can't see how the servo rails are going to fit in without doing that. Anyone have pictures or a better organized installation guide?

Regards,

Michael Wynn
RV 8 Fuselage
San Ramon, CA

Craig23
07-28-2007, 01:36 PM
Michael,

I just installed my servos and had some of the same questions. I searched the forums and found several helpful posts. Paul Dye was a great source of information for me. Here is a link to one of the threads:

http://www.vansairforce.com/community/showthread.php?t=5754&page=1&pp=10&highlight=pitch+servo

Good Luck.

sportpilot
07-28-2007, 05:41 PM
here are pictures of servo installation on an RV9. Maybe this will help orient your installation.
Roll servo in the wing (http://btconline.net/~sportpilot/bums/cleve/100_0387.jpg)

Pitch servo behind baggage area (http://btconline.net/~sportpilot/bums/cleve/100_0310.jpg)

I hope this is helpful.

More pictures of the RV9a here (http://btconline.net/~sportpilot/bums/cleve/cleveone.html)

mannanj
07-28-2007, 07:55 PM
Michael:

As you probably can see from the pictures on the link that Craig posted, you do not have to cut away any of the baggage comp. floor for the pitch servo. All that's really necessary is to replace Van's belcrank brackets with the ones provided by Tru-Trak. Simple as that. The servo mounts to the bracket aft of the belcrank and connects to the belcrank via the arm and rod end bearings (also provided by T-T.

mlwynn
07-28-2007, 08:26 PM
Thanks to all.

I searched but did not find that other thread, so thank you for pointing me to it. The RV 8 mounting bracket is clearly different from the RV 9. The elevator bellcrank brackets are built into the baggage floor ribs. To duplicate what I saw on the link to RV 8, I would need to cut them off and then drill in the new ones from Tru-Trak. No big deal, but it was a little unclear. The upper edge of the bottom of the bulkhead that is just behind this will also have to be modifed slightly for it all to fit. I will measure carefully to be sure I do not move the bellcrank either forward or aft. I didn't want to start cutting until I was sure what to cut.

Again, thanks for your help. Without this list, I would be months behind!

Michael Wynn
RV 8
San Ramon

Rick6a
07-29-2007, 06:53 AM
........All that's really necessary is to replace Van's belcrank brackets with the ones provided by Tru-Trak.......
You don't even need to do that. Why cut away Van's perfectly good bellcrank structure to accomodate Tru-Trak's brackets? All I did was add.... by nesting the Tru-Trak angles over the existing bellcrank assembly after making minor clearance cuts in the bulkhead so the angles would lay flat.

http://img402.imageshack.us/img402/1691/fuselageassembly22715mb3.jpg http://img171.imageshack.us/img171/9556/fuselageassembly27820er2.jpg

AntiGravity
04-02-2008, 09:55 PM
You don't even need to do that. Why cut away Van's perfectly good bellcrank structure to accomodate Tru-Trak's brackets? All I did was add.... by nesting the Tru-Trak angles over the existing bellcrank assembly after making minor clearance cuts in the bulkhead so the angles would lay flat.

Rick, looking at that second picture of yours neatly answered my main question. I was wondering whether to nest rather than replace. Anyway, on my fuse I have two 3/32 round head rivets holding the little reinforcing bracket in place right where the forward end of the trutrak brackets go. Did you have that? I was wondering whether I could shorten the brackets rather that replace the rivets with flush ones (they weren't easy first time around tucked right in there). Or relieve/countersink the underside of the Trutrak brackets, given how small the heads are? Finally, I see your brackets only appear to be held in place with a single bolt; did you rivet them after this, or leave it as is, or what? Thanks,

Jim P
04-02-2008, 10:12 PM
Can't talk about the pitch in the -8, but I assume the roll is identicle to the -7 in the wing. It's fairly easy. The only issue will be running the 7 wires out to the servo.

Steve Sampson
04-03-2008, 04:00 AM
Michael, this might be a bit radical, but I am not sure anyone else has suggested. Try rferring to Trutrak's docs (http://www.trutrakflightsystems.com/docs2.htm). Role and pitch drawings are all there.

Steve.

Rick6a
04-03-2008, 04:58 AM
.......I have two 3/32 round head rivets holding the little reinforcing bracket in place right where the forward end of the trutrak brackets go. Did you have that?......I see your brackets only appear to be held in place with a single bolt.......Jeff,

Its been so long ago, I had to review detail photos to be sure. As you know, TruTrak has not revised its drawings to account for the bellcrank design change. As you can see, I did replace the round head rivets with flush. If you count the 1/4" bolt through the bellcrank, each bracket is effectively secured to the bellcrank flange by two bolts and an aftmost third bolt physically ties both brackets together. As such, I felt the installed brackets are very solid and secure but certainly the point is arguable. If you prefer, you can always add additional rivets similar to Trutrak's drawing illustrating their method of attaching those same brackets to the obsolete RV8 bellcrank assembly our newer design supercedes.

A word of caution: If you do decide to nest the brackets, in keeping with good practice be sure to radius/alodine/prime (as required) the relatively sharp corner of the TruTrak brackets so the edges better conform to the radius on the bellcrank assembly.

http://img201.imageshack.us/img201/7616/fuselageassembly22215nt1.jpg (http://imageshack.us) http://img181.imageshack.us/img181/4762/fuselageassembly22410yo5.jpg (http://imageshack.us)

AntiGravity
04-03-2008, 01:25 PM
Hi Rick, I went ahead and followed your lead last night. After looking carefully at what the intention of the installation was, I radiused the corner and nested the brackets. I also shortened them at the forward end to clear the rivets there; that piece of material length seems redundant anyway. I need to remove for priming, but I may throw a couple of rivets in there anyway, just to be sure. Of course, as you no doubt already found, nesting the brackets increases the effective gap; I needed a couple of AN960-10 washers either end of the aft spacer (or make a new longer spacer), and shall also need to buy a couple of longer bolts. I'm also toying with the idea of reaming the holes in the server and using 'through-bolts' with nuts, rather than simply relying on the threaded hole and safetied bolt head. I don't really want to 'modify' the servo though. Haven't decided that one yet!:)

Thanks for posting your pics. Very helpful.

breister
04-04-2008, 08:02 AM
You don't even need to do that. Why cut away Van's perfectly good bellcrank structure to accomodate Tru-Trak's brackets? All I did was add.... by nesting the Tru-Trak angles over the existing bellcrank assembly after making minor clearance cuts in the bulkhead so the angles would lay flat.

http://img402.imageshack.us/img402/1691/fuselageassembly22715mb3.jpg http://img171.imageshack.us/img171/9556/fuselageassembly27820er2.jpg

Rick,

I notice in your photo that you did not install the servo limit bracket. I would recommend that you make absolutely certain it will not be possible for the servo to "flip around" (is guaranteed mechanically limited) even if the pivot arm to which it is attached gets somehow bent, as this could cause a situation of "reverse controlling" by the autopilot.


Regards,

Bill

Rick6a
04-04-2008, 08:57 AM
......I notice in your photo that you did not install the servo limit bracket...... I would recommend that you make absolutely certain it will not be possible for the servo to "flip around"......Bill
Hi Bill,

You would naturally think that wouldn't you? I did. Here is a link to a thread from about a year ago when I posted a question along those lines. Note TruTrak's response to my query:

http://www.vansairforce.com/community/showthread.php?t=15750&highlight=stops+trutrak