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Recessed elevator trim tab

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mtherr(at)yahoo.com
Guest

Posted: Mon Feb 27, 2006 8:23 pm Post subject: Recessed elevator trim tab

Hello Group,



I would like to install a recessed trim tab on my

elevator.  I remember seeing plans for this, but I

cannot find them anymore.  Anybody would have this in

a file format?



Thanks!



Michel, 170 hours on my 601 HD

Last flight: Lac William, QC



----------------------------

Michel Therrien CH601-HD, C-GZGQ

  http://mthobby.pcperfect.com/ch601

  http://www.zenithair.com/bldrlist/profiles/mthobby

  http://pages.infinit.net/mthobby

Mitch Hodges

Joined: 10 Jan 2006
Posts: 45
Location: Powder Springs, GA

Posted: Tue Feb 28, 2006 10:58 am Post subject: Re: Recessed elevator trim tab

Michel,



Its available on the Zodiac Zenith Builder pages at the Zenith website with the other online PDFs.



http://www.zenithair.com/zodiac/6-manuals.html



Mitch Hodges

_________________
Mitch Hodges
N601MH (Zenith 601HDS)
Builder Log at http://www.hodges.aero
Wings Under Perpetual Construction

mtherr(at)yahoo.com
Guest

Posted: Tue Feb 28, 2006 7:31 pm Post subject: Recessed elevator trim tab

Thanks! On that page, we find an older version of the

trim tab.  However, a new version is on the XL

pages... I'm surprised to see how big is the XL tab. 

Mine is much smaller and already has almost too much

authority.



Michel

do not archive

--- Mitch Hodges <n601mh(at)HODGES.INFO> wrote:



 	  Quote: 	
		   

 <n601mh(at)hodges.info>

 

 Michel,

 

 Its available on the Zodiac Zenith Builder pages at

 the Zenith website with the other online PDFs.

 

 http://www.zenithair.com/zodiac/6-manuals.html

 

 Mitch Hodges

 

 --------

 N601MH (Zenith 601HDS)

 Wings Under Construction

 

 

 

 

 Read this topic online here:

 



http://forums.matronics.com/viewtopic.php?p=18483#18483
	


 	  Quote: 	
		   

 

 

 

 

 

 

 

 



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----------------------------

Michel Therrien CH601-HD, C-GZGQ

  http://mthobby.pcperfect.com/ch601

  http://www.zenithair.com/bldrlist/profiles/mthobby

  http://pages.infinit.net/mthobby

zodierocket(at)hsfx.ca
Guest

Posted: Tue Feb 28, 2006 8:23 pm Post subject: Recessed elevator trim tab

Michael the larger trim tab is for the LSA requirements in which they

are using 0-200's and Jab 3300's and require less stick pressure in full

flap configuration. Your right it is way to much for normal flying

conditions and I would not alter from the original design of the

recessed trim tab. Bigger in this case is not always better, but for the

U.S. Sport Pilot it is necessary and the 601XL plans have evolved to

suit this category.



Mark Townsend  Alma, Ontario

Zodiac 601XL C-GOXL, CH701 just started

www.ch601.org / www.ch701.com / www.Osprey2.com

--

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Tue Feb 28, 2006 11:05 pm Post subject: Re: Recessed elevator trim tab

Although the larger trim is too sensitive for level flight, I personally would stick with the larger trim, but add a SERVO SPEED CONTROL to reduce the sensitivity. I've been told by some to simply add a resistor, but that would reduce the power level to the servo, making it weaker as well as slower. The servo speed control does it without reducing power/strength.



I'll tell you a little inside info on why that tab is so large on the XL. 



The LSA requirements state that it must be possible to trim the aircraft for level flight with full flaps. The first ELSA 601XL (CZAW-built) was modified from plan to include the larger tab for this reason. That particular aircraft can be trimmed for level flight with 25 degrees of flaps.



It was a point of contention with Zenair that CZAW deviated from plan on the trim tab, but it was not a critical item because of the aircraft category (ELSA). 



When it came to the subsequent CZAW-built SLSA (more strict rules) Zenair insisted on the smaller trim tab, as per the plans. As a consequence, the flaps were purposely limited to only 10 degrees because the trim tab is not adequate enough for a higher flap angle (according to LSA rules).



Then comes along the AMD-built SLSA, which was extensively flight tested; a job well done and highly complimented by the FAA. I know the test pilot, so I know a littlle about the tests they did. Anyway, I can only surmise that the XL plans were modified to include a larger trim tab as a consequence of the testing done at AMD. I would imagine more than a few design changes came out of that work.



So in the end, CZAW had it right in the first place (as far as the trim tab) but I guess everyone's farts stink except their own. Too bad the SLSA customer got shafted with a 10 degree flap limit.

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

p.mulwitz(at)worldnet.att
Guest

Posted: Wed Mar 01, 2006 4:04 am Post subject: Recessed elevator trim tab

 	  Quote: 	
		  I've been told by some to simply add a resistor, but that would 

reduce the power level to the servo, making it weaker as well as 

slower. The servo speed control does it without reducing power/strength.


	


I'm really confused by this one.  It seems to me that to reduce the 

speed of the servo motor you must reduce the voltage supplied to 

it.  That naturally reduces the power to the motor.  There just ain't 

no other way for this to work.



I think the actual circuit required to do this electrically is a 

voltage divider.  Since the voltage to the servo motor is actually 

reversed, this would require separate divider networks for each of 

the wires that supply power to the servo motor.  The total number of 

resistors needed for this approach would be 4 and the grand component 

cost around 50 cents.



A similar approach could be done mechanically by increasing the 

length of the trim tab control horn.  In this case, the power would 

actually be increased by slowing down the trim tab movement due to 

the increased mechanical advantage.



I guess this leaves me completely baffled when I try to understand 

why the design is so poor that you can't actually trim the plane for 

level flight with the final design.



Paul

XL wings

mtherr(at)yahoo.com
Guest

Posted: Wed Mar 01, 2006 6:28 am Post subject: Recessed elevator trim tab

Good information ... thanks to all who responded.



Michel

do not archive

--- Zodie Rocket <zodierocket(at)hsfx.ca> wrote:



[quote] 

 <zodierocket(at)hsfx.ca>

 

 Michael the larger trim tab is for the LSA

 requirements in which they

 are using 0-200's and Jab 3300's and require less

 stick pressure in full

 flap configuration. Your right it is way to much for

 normal flying

 conditions and I would not alter from the original

 design of the

 recessed trim tab. Bigger in this case is not always

 better, but for the

 U.S. Sport Pilot it is necessary and the 601XL plans

 have evolved to

 suit this category.

 

 Mark Townsend  Alma, Ontario

 Zodiac 601XL C-GOXL, CH701 just started

 www.ch601.org / www.ch701.com / www.Osprey2.com

 

 

 --

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Wed Mar 01, 2006 11:11 am Post subject: Re: Recessed elevator trim tab

My understanding of how the server speed control works is that it uses pulse width modulation to control the speed of the motor - i.e. the power is switched on an off rapidly to the motor as opposed to simply reducing the voltage.



Your idea of using a longer control arm would also require a servo with a longer travel. A common servo used for the trim tab is a MAC 4A with a .7" travel and 10 seconds of travel time. The MAC 6A has 1" of travel and 16 seconds of travel time.  That might be a good compromise.



My only guess about the small trim tab is that it was a leftover from the HD, HDS and UL designs which don't have flaps. I'm happy that Zenair is always improving the design, though.

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

dougsire

Joined: 10 Jan 2006
Posts: 37

Posted: Wed Mar 01, 2006 11:38 am Post subject: Recessed elevator trim tab

Ray Allen Company's web site offers some more information and opinions in

this area.   They offer a servo speed control, and their FAQ page

addresses some pros and cons of slowing down a servo.



Doug Sire

601XL

_________________
Doug Sire 601XL
Do Not Archive

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Wed Mar 01, 2006 11:56 am Post subject: Re: Recessed elevator trim tab

An interesting idea in the FAQ. A switch/sensor in the flap control could be used to bypass the speed control. The speed control could be bypassed when flaps are used. With flaps up (cruise) the speed control is active to help reduce sensitivity.

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Wed Mar 01, 2006 6:16 pm Post subject: Re: Recessed elevator trim tab

Found a good computer for trim horn length calculations. http://www.rayallencompany.com/RACmedia/trimtabtravelcomputer.pdf

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

zodierocket(at)hsfx.ca
Guest

Posted: Sun Mar 12, 2006 4:46 am Post subject: Recessed elevator trim tab

Reminder, For all of you attending Sun-N-Fun Please come out to the 2nd

Annual Webmasters BBQ for owners and Builders of Zenith Aircraft. This

years event is being held on Thursday April 6th once again in the

campgrounds. Last years event saw a total of 125 people, hopefully this

year we will have as good or better showing. There is no sign up sheet

this year or name tags but to get an Idea I would like everyone planning

to attend to send me an E-Mail. At moderator(at)ch601.org or

moderator(at)ch701.com or hit reply and add a "do not archive" This way I

can purchase dogs and burgers accordingly Presently I have 40 people

signed up, but we about 2/3rds short from last years event. There is no

cost as it is coming out of my pocket and from Donations. Last year we

had donations of food and somebody brought a great flat of Strawberries,

I'm glad to report that Jabiru USA has once again generously donated to

our event.  Rick Roberts has once again signed up his guys to handle the

Grills. The BBQ starts at 5 pm just after the show and runs till 8pm

when the trolleys stop running. The location will be posted in the

Zenith booth or just ask any member of the Zenith team. Builders, Owners

or dreaming of a Zenith are all welcome.



Remember this is your time to spend with others doing the same thing you

are, also The whole Zenith Crew will be present just for you. There are

no speeches just a great time sharing stories!!! Please send us an

E-Mail we really don't want to run out of food or have to run out

Thursday afternoon for more supplies just before the event. I look

forward to meeting everyone.

Mark Townsend  Alma, Ontario

Zodiac 601XL C-GOXL, CH701 just started

www.ch601.org / www.ch701.com / www.Osprey2.com

 



--

planejim(at)bellsouth.net
Guest

Posted: Sun Mar 12, 2006 5:59 am Post subject: Recessed elevator trim tab

Hey Listers,



You can also come by the Basic Sheet metal Workshop for directions to where 

in the campground. It will be in the area of my camper.



Jim Hoak  601HD



Do not archive

---

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