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Rudder trim input needed
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plevenda@jvlv.lv

Joined: 12 Oct 2007
Posts: 6
Location: Mesa, AZ

Posted: Fri Oct 12, 2007 11:22 pm Post subject: Rudder trim input needed

Hey fellow builders and flyers. My name is Paul Levenda and I'm a new builder in AZ. I first of all want to thank all you who have been contributing to this forum. I had several months to just browse the forum before building, and my head is swimming in all the great information given by those of you who have blazed a great trail for us young ones following behind.



My question has to do with the much talked about rudder trim. I have seen Vic's, and I've seen the other comments on the forum, but I have talked with an A&P buddy about installing a rudder trim simular to a regular electric trim tab you see mostly on twins. I am at a stage where my rudder is still in two halves so I want to look at this possiblilty now. I'm thinking I could cut and build a trim tab between two sets of stiffeners and then install the Ray Allen servo as Vic did. I do not want do any thing drastic until I have my A&P friend come look at my plan, but I wanted to see what thoughts the Matronics group might have as well.

_________________
Paul Levenda
#40090
N974LV

dherring10

Joined: 29 Apr 2007
Posts: 11

Posted: Sat Oct 13, 2007 6:18 am Post subject: Re: Rudder trim input needed

Paul,



I installed one just like Vic did but when I was at Sun-n-Fun this year I saw the one Jesse Saint used on one of his planes. I liked it a little better because it was smaller and installed lower on the rudder below the elevator. Maybe Jesse will post some pictures for you if you ask him.

 

I do know if you are going to install one it will be much easier to do it before you put the rudder together.

Dwayne Herring

40506

QB fuse (about to start the fiberglass work, Yuk!)

rene(at)felker.com
Guest

Posted: Sat Oct 13, 2007 6:34 am Post subject: Rudder trim input needed

Look at this ref, but I stole Vic's idea, will let you know how it works

once I am flying.....



http://forums.matronics.com/viewtopic.php?p=90306#90306



Rene'

40322

N423CF

Finish......ing

801-721-6080

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plevenda@jvlv.lv

Joined: 12 Oct 2007
Posts: 6
Location: Mesa, AZ

Posted: Sat Oct 13, 2007 7:46 am Post subject: Re: Rudder trim input needed

Thanks for the input. I have viewed a few threads on rudder trim before, but after doing a search on "Aerotrim", I have found that there has been  a lot more talk on adjustable rudder trim that I missed in the past. Again, a lot of good information, thanks.

_________________
Paul Levenda
#40090
N974LV

jesse(at)saintaviation.co
Guest

Posted: Sat Oct 13, 2007 9:02 am Post subject: Rudder trim input needed

We are working on a system exactly like this.  Let me know if you come up

with something and I'll do the same.



Jesse Saint

Saint Aviation, Inc.

jesse(at)saintaviation.com

www.saintaviation.com

Cell: 352-427-0285

Fax: 815-377-3694

--

greytex

Joined: 29 May 2006
Posts: 28

Posted: Sat Oct 13, 2007 10:47 am Post subject: Rudder trim input needed

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  So Paul you and kit # 90? If you are new maybe 40790?

  

 John Cram

 40569

 [quote]   ---

kearney(at)shaw.ca
Guest

Posted: Sat Oct 13, 2007 8:08 pm Post subject: Rudder trim input needed

Paul



Below is a link to Tim Olson's site which has pictures of the rudder trim

system used by Vic Syracuse on his -10.



http://myrv10.com/tips/mods/RudderTrim/index.html

I have shamelessly stolen his design and used it on my -10 (which is still

in bits in my garage). The major difference between Vic's and mine is that I

have placed the servo lower on the rudder and made the trim tab a bit

smaller.



I will l know in about 18 months how well it works.



Cheers



Les Kearney

#40643

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Bill Reining

Joined: 13 Aug 2007
Posts: 13
Location: Oakland, California

Posted: Sat Oct 13, 2007 9:34 pm Post subject: Re: Rudder trim input needed

Paul

I am also interested, but haven't done anything yet.  I did take the attached pictures of the Ray Allen display while at Oshkosh this summer.  Hope they help.

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_________________
Bill (and Jon) Reining
40514

ricksked(at)embarqmail.co
Guest

Posted: Sat Oct 13, 2007 10:32 pm Post subject: Rudder trim input needed

Deems and I are working on a rudder trim system that will deploy a flush tab (similar to airline speed brake) into the slip stream on each side of the rudder. I have a rough sketch not worthy of posting yet but I'm sure we will keep the list informed as it develops. One thing for sure, it will be a bunch easier to so during assembly than after the fact but we are working on the after the fact version. I already have the aircraft and panel wired for it, it's on the back burner until I can get the canopy top final riveted. Look for for a good drawing and some pics in about two weeks. It will use the Ray Allen servo. It works on paper, just need to carefully start the layout and see where and how to fit it. The plan is for the control to be tray mounted to allow access to the servo and linkage and the actual control surfaces will be mounted using hinges, nutplates and screws. The weight should be equivilent to Vic's setup. Of course there will be a need to balance the rudder afterwards to make sure there isn't a flutter issue with the extra weight built into the control surface.



Rick S.

40185

---

wcurtis(at)nerv10.com
Guest

Posted: Sun Oct 14, 2007 10:49 am Post subject: Rudder trim input needed

And now for something completely different.



My rudder trim will require absolutely NO modifications to the rudder.  The Van's aileron trim system uses a spring bias mechanism and I'm surprised no one has considered using a similar system for the rudder trim.  My Cardinal 177RG uses a mechanical spring bias system and I intend to develop a similar fully mechanical spring bias spring system for the RV-10.  



In the Cardinal, the mechanical trim wheel is turned moving an actuator that applies (or removes) pressure to the rudder pedal assembly to effect rudder trim.  The same spring bias mechanism that is used for the aileron trim may be usable for the rudder trim. 



William

http://wcurtis.nerv10.com/ 



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rv10(at)sinkrate.com
Guest

Posted: Sun Oct 14, 2007 11:10 am Post subject: Rudder trim input needed

I am curious if anyone has given any thought to a system that applies forces

to the cables without any external tabs?  It seems to me the cables could be

cut into two pieces somewhere in the tailcone or tunnel and some sort of

linkage could be created so that the pedals are always neutral but the rear

half of the cables that are attached to the rudder could be offset such that

they make the rudder move a few degrees either direction.  



I have a few ideas of some systems but I don't have a clue as to what would

work or where to start.  Just curios what other people have thought of?



-Ben

40579

--

ricksked(at)embarqmail.co
Guest

Posted: Sun Oct 14, 2007 12:02 pm Post subject: Rudder trim input needed

The Rvator had a manual system for the -6 a few years back that involved springs and pulleys, basically as you turned the knob, it would apply tension to one or the other spring to move the rudder left or right. It is similar to the RV-10 aileron trim. I drew several different variations but the reason for not doing it came down to one main reason...adding more potentential failure points that would or could cause catastrophic rudder failure. Honestly, Vic's system is very simple, if it fails at any point it shouldn't really be an issue of flight. I am still sold on that version but will try to reinvent the wheel. The method we are working on does use springs to keeep the tabs closed, the trim servo overrides the spring pressure. If it fails it will either keep the trim at it's last point, or the tab will close. Either way I guesstimate that the forces will not be significant enough that I can't use my two foot pounds of pressure to keep it straight. 



Rick S.

40185

---

ricksked(at)embarqmail.co
Guest

Posted: Sun Oct 14, 2007 12:06 pm Post subject: Rudder trim input needed

Wish I had read your post first before posting mine William, could have saved me a few lines in my message. Please share you ideas as they develop. My main concern was springs that were able to provide enough travel and still maintain their springyness and not be so strong that they would wear your legs out but strong enough to hold position on the rudder. I toyed with ways to attach the system to the cables instead of cutting the cables and installing the aprings inbetween, what say you?



Rick S.

40185

---

coop85(at)cableone.net
Guest

Posted: Sun Oct 14, 2007 12:57 pm Post subject: Rudder trim input needed

FWIW, I too had considered a spring system for the rudder trim.  Part of the

problem is it's not a closed loop system so at first look you'd have to have

a system that works both sides.  One thing I considered is that since you

usually only have to hold right rudder in you could just but a spring on

that side to hold some tension pulling on the right side at various amounts.

The amount of throw threw me off though and I finally caved and put a tab on

the rudder that I operate through a push/pull cable to a knob in the

cockpit.  Honestly it's not the prettiest setup so I may redo it down the

road, but it cost next to nothing and it works great.



Marcus

Picking it up from the paintshop next weekend!



--

wcurtis(at)nerv10.com
Guest

Posted: Sun Oct 14, 2007 1:45 pm Post subject: Rudder trim input needed

Yeah, cutting the cables would be an absolute no-no in my book.  In one scenario I'm attaching the mechanism to the rudder pedal assembly, in the other, to the rudder cables via a "wire rope clip" that allows attachment of an actuator arm.  The secondary effect of this system would be to provide automatic centering to the rudder.   Since this won't require the constant attention like the pitch trim, this is the reason I'm strongly favoring a fully mechanical system.  One question for those that are flying with a rudder trim; once set how ofter do you have to change it?



William

http://wcurtis.nerv10.com/ 



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wcurtis(at)nerv10.com
Guest

Posted: Sun Oct 14, 2007 2:41 pm Post subject: Rudder trim input needed

I'm not sure I'd agree that it is not a closed system.  Simultaneously pushing right and left rudder will not give you both right an left deflection--but I think I know what you mean.



Using springs to hold only one direction would require a somewhat large force, this would be the case for the aileron trim also.  Anyway all that is required is a bellcrank, two pulleys and two springs attached by cables to the forward side of the inboard rudder pedals .  With the bellcrank centered, the springs will center the rudder.  With the bellcrank to one side or the other, the springs will bias the rudder to one side or the other.  There are various ways that the actuator moving the bellcrank can achieve the required mechanical advantage.  You could even eliminate the actuator by making it ground adjustable fixing the bellcrank with the center bolt.  Some have already added springs to the forward side of the rudder pedals to eliminate the "free play" of the rudder pedals.



William

http://wcurtis.nerv10.com/ 



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jesse(at)saintaviation.co
Guest

Posted: Sun Oct 14, 2007 5:10 pm Post subject: Rudder trim input needed

In my experience, the rudder trim is used every flight, set to climb, set to

cruise, and not always the same setting for cruise because of loading.  I

haven't measured the amount that is used or whether it is only one side or

not, but I do know it is useful to have.  IMHO, if you have it, you will use

it and will be glad you have it.  Aileron trim would be easier to do

without, I think, especially if you have an auto pilot, as it somewhat acts

as an aileron trim when engaged, although I would still recommend it so you

are not always holding a load on the servo.



All IMHO.



Do not archive



Jesse Saint

Saint Aviation, Inc.

jesse(at)saintaviation.com

www.saintaviation.com

Cell: 352-427-0285

Fax: 815-377-3694



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poneill(at)irealms.com
Guest

Posted: Sun Oct 14, 2007 6:15 pm Post subject: Rudder trim input needed

Here's the spring bias rudder trim for the Rv-6:



http://bmnellis.com/BuilderIdeas/ruddertrim.htm



I've been thinking a lot about this during the build.  I really would prefer

some form of spring bias system to avoid changing the balance

characteristics and construction of the rudder.  I've thought about it a lot

but have been waiting until I have more of the rudder system installed to

get a better idea of function.



I'm very eager to see if others make any progress with a spring bias trim

system.



Best Regards,

Patrick #40716



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planesmith(at)hotmail.com
Guest

Posted: Sun Oct 14, 2007 8:03 pm Post subject: Rudder trim input needed

At Van's home coming, there was a 10 builder with a spring bias system using a trim servo motor. It was mounted in the tunnel between the two rear seats, so I didn't get to see the mechanism. The biggest challenge was the inherent drag in the rudder system which was too great for the bias springs to over come. So it was still a work in progress and a very interesting concept.

  

 Vern Smith (#324 cabin top)





   

 > From: rv10(at)sinkrate.com

[quote] To: rv10-list(at)matronics.com

 Subject: RE: Re: Rudder trim input needed

 Date: Sun, 14 Oct 2007 12:01:43 -0700

 

 --> RV10-List message posted by: "Ben Westfall" <rv10(at)sinkrate.com>

 

 I am curious if anyone has given any thought to a system that applies forces

 to the cables without any external tabs? It seems to me the cables could be

 cut into two pieces somewhere in the tailcone or tunnel and some sort of

 linkage could be created so that the pedals are always neutral but the rear

 half of the cables that are attached to the rudder could be offset such that

 they make the rudder move a few degrees either direction. 

 

 I have a few ideas of some systems but I don't have a clue as to what would

 work or where to start. Just curios what other people have thought of?

 

 -Ben

 40579

 

 

 --

johngoodman

Joined: 18 Sep 2006
Posts: 530
Location: GA

Posted: Mon Oct 15, 2007 6:54 am Post subject: Re: Rudder trim input needed

As the rest of you, I've been mulling this over, as well. I saw an earlier post concerning the spring system on the firewall in front of the passenger pedals before, and it seems like the most practical. It's mechanical and is not attached to the actual rudder cables. It's close to the pilot so an emergency trim disconnect cable would be easy to install. It could also take the slop out of the pedals and prevent the rudder from slamming the stops in windy ramp conditions.



Just to start some more dialogue, you can change yaw without the rudder. I'm not pushing this but a small vane in the airstream can do the same thing. As an example, you could put a vane on the belly with a simple twist knob. It would need to be aft of CG to avoid reverse action and the further back the smaller it could be. Drag would not be a big issue since the device would be reducing the drag effect of unbalanced flight. Fire away.

John

_________________
#40572 Phase One complete in 2011

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