Uneven trim tabs...

[pierre smith]

The other day, someone noticed that my -10's two elevator trim tabs were not even, with one about 1/4"-3/8" lower than the other. Someone at Van's said that that's correct....for engineering purposes and for 'feel'. He didn't elaborate and I'd appreciate further explanations from some of you engineering types on here.

Thanks,

 

[N941WR]

Piere,

How do you like the -10 vs. the -6?

Caution, hi-jacker at work.

 

[RV10Man]

re: even?

Pierre:
Just for grins and giggles run the trim all the way one direction. I can't remember which one, but when you run the trim all the way for nose down (I think) to the stop, one of the tabs stops at neutral while the other one continues up. It may be for nose up, then all that I said will be backwards.
Of course, do this on the ground.

Marshall Alexander

 

[Mike S]

Pierre, old issue, and an non-issue.

Fly on.

Lots of info if you really want to do a bit of searching.

Congrats

 

[pierre smith]

No comparison...

Piere,

How do you like the -10 vs. the -6?

Caution, hi-jacker at work.

...and actually a little disappointing. It flies like a deuce-and-a-half compared to my -6. I thought that it'd be closer to a -9 but it stands alone as the family Suburban that you load kids, dogs and baggage into. You make a turn on course, activate the autopilot and wait 'til you arrive at your destination and make a turn to final and land, trimming often as the flaps go down because it'll take two hands if you don't. Haven't had two in the back yet and they say it gets lighter on the elevator when you do because the CG sure is far forward with full fuel and two up.

It sure ain't my -6 but then again, it has a completely different mission. It's lighter than a Skylane but heavier than I'd thought it would be. Man, I wish that I could keep my -6

Regards,

 

[Rick S.]

Wow...a Duce and a half!! I gotta try me one of them little RV's
But you hit the nail on the head, takeoff, head in the general direction with the A/P on then land at your destination. Add a 480 coupled to the TT RV-10 AP (which gives me a secondary RV Grin) and it gets real boring if you let it! It hand flys real nice too. It does land differently with someone in the back, not so much easier than different. Mine flys a bit faster with a rear passenger, little less up trim required makes a difference. You get used to trimming as the flaps come down, at first I couldn't beleive the back pressure required until my brain kicked in and said hey...trim! For anyone building a -10 who has not been to rigging the trim tabs research the Matronics and here. Bill DeRouechy, (Sorry for messing up your name Bill) Describes the perfect procedure. Also pay attention to how much of the trim cables extend past the HS spar. They need to be routed exactly as the plans show or you will scratch your head for 8 plus hours trying to figure out why you can't get the tabs to get even close to nuetral let alone provide any "up" trim. Ask me how I know as they say! One thing the PIB's (Passengers in the back) are saying is they can really feel the yaw movements, especially when I sorta green faced my S.O. coming back from Burbank a week or so ago, pretty choppy and a strong x wind returning to KVGT. She said that the tail was moving around a lot when we landed. Actually it was one of my best cross wind landings to date, Right wheel, left wheel slowly after that and aerobraking till the nose wheel squeaked. The -10 really does nice crosswind landings.

 

[Rick S.]

Van's said that that's correct....for engineering purposes and for 'feel'. He didn't elaborate and I'd appreciate further explanations from some of you engineering types on here.

If I recall, the reason originally was Van's planned to have an auto trim feature that would adjust the trim according to flap position but word on the street was it was way to much effort and not needed so it went by the wayside. I have thought about changing mine so the tabs are symetrical in operation but I get so many "Why" responses I just leave it as designed.

 

[flion]

Auto-trim

Now I'm curious. Anyone using a Sorcerer with auto-trim in a -10? I'm just wondering how it works because I'd expect it to be designed for a more linear response than I'd expect to see from the differential trim setup in the -10. Notice the word 'expect'; I haven't really tried to think this through before looking for some real-world data. But I'm planning to put the Sorcerer in mine, with auto-trim and yaw-damper, and would like to know if I need to make any adjustments before I actually install Van's trim system.

 

[N941WR]

...and actually a little disappointing. It flies like a deuce-and-a-half compared to my -6. I thought that it'd be closer to a -9 but it stands alone as the family Suburban that you load kids, dogs and baggage into. You make a turn on course, activate the autopilot and wait 'til you arrive at your destination and make a turn to final and land, trimming often as the flaps go down because it'll take two hands if you don't. Haven't had two in the back yet and they say it gets lighter on the elevator when you do because the CG sure is far forward with full fuel and two up.

It sure ain't my -6 but then again, it has a completely different mission. It's lighter than a Skylane but heavier than I'd thought it would be. Man, I wish that I could keep my -6

Regards,

We were teasing a friend about building a mini-van.

You are right, you need to go fly a Cessna or Piper sometime soon. That will remind you what a great plane the -10 is.

Forget the -6 BTW and start building a -3. You can tuck it in the same hangar as the -10.

 

[TSwezey]

Pierre come down to the coast and fly your -10 about 30-50 feet off the sand, marshes and water. You'll feel alive in your -10! No it's not a 6,7 or 8 but it can be a lot of fun!

 

[dmaib]

You will find Bill DeRouchey's (sic?) method for setting up the pitch trim tabs over on Matronics at
http://forums.matronics.com/viewtopic.php?t=20576&highlight=elevator+trim+tabs

I used this method and it works great. No trim problems. As I recall, Bill talked with Van's about this issue. It pops up on the forums about once a year or so.

 

[RudiGreyling]

Hi Pierre, I asked VansAircraft because there are to much miss-information on the forums...from the horses Mouth in an email to me

Engineering started out early in the process with the intent to link one of the trim tabs to the flap linkage in order to reduce pilot initiated pitch trim during flap deployment. A significant amount of time went into the design and the original flights were made with this flap/trim linkage in place. During flight test, it was determined that the linkage was not necessary and that both tabs could simply be run off the servo without linking to the flaps. Rather than spend a bunch of time changing the design, the connection to the flaps was deleted and the geometry of the linkage at the servo was left alone. You'll notice that one of the trim tabs pretty much stops at neutral and does not go up (nose down trim) beyond that. The other tab does continue on up and supplies the 'less needed' nose down trim but with less 'umph'.

Both tabs move down providing ample nose up trim during the landing phase. Having flown the plane quite a bit, I wouldn't want both tabs moving above neutral during nose down trim input...plenty as is.

That explaination makes sense, doesn't it?

That said the rigging of it is important, when you rig it make sure you dont have one trim tab above and one below neutral, during the travel range.
Here is some good information:
http://www.myrv10.com/N104CD/maintenance/20080622/

Kind Regards
Rudi

 

[pierre smith]

It makes good sense...

....and others agree,

Thanks,

 

[Rick S.]

Now I'm curious. Anyone using a Sorcerer with auto-trim in a -10? I'm just wondering how it works because I'd expect it to be designed for a more linear response than I'd expect to see from the differential trim setup in the -10. Notice the word 'expect'; I haven't really tried to think this through before looking for some real-world data. But I'm planning to put the Sorcerer in mine, with auto-trim and yaw-damper, and would like to know if I need to make any adjustments before I actually install Van's trim system.

I'm using the RV-10 AP,pretty much the same in operation. I kinda wish I used the auto trim add on but only when encountering turbulance. The AP asks you to trim up/down occasionally during decent and climb but in the chop it's a lot more active. No big deal besides short of talking to ATC and monitoring your systems, what else ya gotta do?

 

[David Shelton]

Just a thought...

The airplane's left-turning tendencies are a little different at low and high speeds. If properly designed, unevent trim tab movement could be used to provide corrective roll trim. I'll have to take a closer look at the -10 as I'm curious if the stock setup is working for or against us in this regard.

 

[kevin O]

I installed TT auto trim on an RV 10 AP. Really pleased with it. Can pull back pwr on glideslope and ac will automatically go to attitude that pwr is set for ie 90kts on ILS. no more chasing the trim setting.

 

[RV10inOz]

David

I think ours and most RV-10s want to Roll to the right. Factory one does, and hence they have a tab under the left aileron ....just like we do! They did say that the odd one rolls right

Not sure the trim tab is causing the roll.....

 

[edbooth]

Elevator trim

....and others agree,

Thanks,

Hey Pierre, You should have given me a call, I could have helped you a little. Just got Greg's straignted back out after the paint shop reinstalled the elevators and tried to get them to both work together.....aaaarrrgggghhh!

See ya Ed Booth