Elevator trim

[akflyer 1427]

Hey terciops,

Can you post a pic of how you did the aerovee install?  I have electric trim on mine, but if this works better, and you get more speed/better climb/less drag, I am all for it.  The price is right for sure.

[terciops 0]

Hi Akflyer - certainly - only a pleasure.

The link to the photos is here : http://picasaweb.google.co.uk/Ken.B.Smith/TheWattleWitchAvidSpeedwingIV#

Check out the last 2 that show the underseat and panel units.

My comments on the installation on the Avid User Group were :

I have now fitted and flight tested the Aeroconversions trim unit to my

Speedwing IV - ZK-RWT. As promised - here are some thoughts :

http://www.aeroconversions.com/products/trim/index.html

The item arrived promptly considering the distance it had to travel to NZ.

Nicely overpacked in a rigid box and all parts for the standard conversion were

neatly bagged. Instructions are not for the AVID of course, but easily

understandable.

I had to make an aluminum T piece to mount the cable end under the seat and

drill 3 holes in the throttle mount bracket to hold the trim wheel unit. Plenty

of cable for a long looping run - indeed I cut about a foot off. Two springs

are supplied - one down and one up. My Avid does not need down trim so I put

both springs on the Up side after finding by ground testing (I have all my stick

force numbers from my initial flight tests) that 1 was not quite enough.

I adjusted the cable so that with full DOWN trim selected the springs were free

of the elevator rod and the trim was essentially how it is normally - very nose

heavy at all but high speed. Total installation time including hoovering up the

mess - 1.5 hours.

I also took this opportunity to seal the elevator gap in the tailplane using

tape in the reverse "S" method and remove the elevator fixed tab bias to neutral

- it was previously quite significantly nose up.

A flight test this morning gave me an aircraft that was 'night and day' from

what I had before.

It trimmed out at all speeds and flap settings, finals with half flap and 55kts

could be flown hands off and the flare was a delight without that residual back

pressure. The elevator sealing was obvious in the progressive control into the

flare and no sense of elevator stalling at higher pitch rates that was apparent

previously.

Rolling at that trim setting leaving half flap down produced a small requirement

for forward stick pressure (2lbs) when airborne, but a half turn on the trim

knob took that away. Raising flaps gave me another 2 lbs of forward and another

half turn was needed to climb out at 60kts. Very easy and positive to use. The

trim knob is a little close to the throttle and only finger tips can be used to

turn it. But the force required is very small and this is not a problem.

Another half inch to the right would be ideal, but this will require another

bracket and it is not worth the bother.

Cruise and Descent were delightful and I could set any speed I wanted regardless

of power and flaperon and it would fly stick free and stable.

I had previously taken out the fixed trim tab biase to 'nose up' when I put on

the elevator sealing tape. These two mods together have improved my solo + 65

litres of gas (830 lbs AUW) climb from 750 fpm to 950+ fpm and put about 5 kts

on my cruise. The whole pitch control now feels much more positive and with the

ability to trim properly has made the 'Witch' a little joy to land rather than

the rather difficult and twitchy thing she was prior.

A subjective note is that the rudder now seems more sensitive and she wanted to

yaw about more. This could be a result of less turbulence in the tailplane area

as a result of the elevator gap sealing. Or it could just be me I will fly

her some more and figure that one out.

So - $95 for the trim, $2 for some tape and a couple of hours work have been the

best value for money mod I have done on any aircraft in the past 45 years of

flying

Highly recommended.

Ken

[terciops 0]

Further on the Trim install.  I have been playing with the elevator sealing and there is no doubt that the tape in a "S" pattern on the elevator hinge is a huge plus for performance - on my machine anyway.  I am doing the rudder hinge tomorrow and see if I can squeeze a few more FPM out of her to make the magic 1000fpm climb at solo weights (820 lbs or so).  A bloody good target for 65 hp and a drag master

The removal of the big bias on the fixed elevator tab is also a factor - albeit not such a big one.  Trim drag from a fixed or movable aerodynamic trimmer is a source of drag.  We used to avoid using them many years ago when I used to fly competition gliders for that reason.  However there are so many other sources of parasite drag on the Avid that I don't think this is that significant.  However as the old woman who peed in the pond said - "every little helps".

Now to get those dead flies off the leading edge too and a coat of polish .....

Ken

[akflyer 1427]

Thanks Ken,

Hope you dont mind, but I am putting the two pics right here so they show up in this thread.  Looks like a damn easy way to go for elevator trim.

[84KF 4]

Leni...,

    Here is an idea 'specially suited for you...  http://unclemikey.blogspot.com/2004/09/greg-boyington-crazy-sob_24.html

"I used to envy the bomber pilots, who had automatic pilots in their planes. So, for lack of an automatic, I would take along rubber bands and pieces of string, and I would rig these up on the instrument panel and on the brackets on the side of the cockpit, and I would have them all fixed up so that I could sleep most of the way going up to enemy territory. I would loosen my safety belt and half crawl out of my parachute straps, and then I would doze off.

"Rarely would I have to glance at the altimeter, for I was able to tell by the sound of my engine whether I was going up- or downhill. So, without opening my eyes, I would just reach out and tap the rear string, and everything would sound right and I could doze off again.

"If one wing dropped, I would lurch over to that side, gently tap the rubber band, and when the adjustment was made and I was sitting on an even keel, I would doze off once more."

[akflyer 1427]

  necessity is the mother of invention   damn, you are putting bad bad ideas into my head.  dont think I would get much sleep behind a 2 stroke.. the RPM changes with every bump in the sky.  I do remember a flight in a PA 12 years ago that I did fall asleep for about 15 miles... scared the ever loving crap out of me.  Good thing it was trimmed and rigged right, cause I was only about 4-500' off the deck.  That flight SHOULD have ended very badly.

[C5Engineer 1170]

I am going to look into this system. My bird is nose heavy and I'd love to be able to trim off the forces. Terciops any chance for a few more pics of the routing from the knob to your elevator pushrod? Thanks

[DIVE4IT 0]

I own an Avid A model but also have one of the Sorrel SNS-8 stagger wing biplanes. There is a similar mixer control under and along the sides of the seat. On some long distance trips, I loosen my belt and slouch down in the seat (unlimited legroom compared to the Avid) and rest my hand on one of the mixer push tubes beside the seat. Controls were reveresed from what would be natural but could pretty much fly the plane with one eye closed. A simple tilt of the head a slight lean would keep roll under control....oh, those were the days.

JT

[akflyer 1427]

I own an Avid A model but also have one of the Sorrel SNS-8 stagger wing biplanes. There is a similar mixer control under and along the sides of the seat. On some long distance trips, I loosen my belt and slouch down in the seat (unlimited legroom compared to the Avid) and rest my hand on one of the mixer push tubes beside the seat. Controls were reveresed from what would be natural but could pretty much fly the plane with one eye closed. A simple tilt of the head a slight lean would keep roll under control....oh, those were the days.

JT

Is that the hyperbipe? I remember years ago reading a magazine actilce about some lady setting a looping record at that time in the hiperbipe for most consecutive loops. I wanted one of those planes in a bad way back then. Still think they would be a blast to fly!

[High Country 69]

Sorry to bring up old posts but I've been looking into doing a trim tab on my avid. i have already installed a Model IV elevator with the tab but am now looking for a way to make it function. I really like the idea of a mechanical system such as this one if i could find a long enough cable to reach the trim tab, I'm thinking that the rans cable might work aircraft spruce part# 11-09970. I don't really have enough room in my B model for the wheel on the floor mount. Does anyone have any more current reports of this system, do you think it will hook up to the rans cable? Sounds like just what I'm looking for.

-Robert-

Edited 19 Feb 2012 by High Country

[SuberAvid 617]

Although they are a little expensive, I have the Ray Allen electric trim servo on the trim tab and with the buttons on the stick and love it. It becomes almost subconcious to trim the plane; just little bumps on the buttons unless you are running the trim to the limits for TO and landing; then just hold the buttons down as long as you need.

[High Country 69]

I have a Rotax 532 so I'm pretty limited on power output (10 amps) so i am trying to make as much manual or self powered as possible to reserve the power for lights

-Robert-

[Bandit 286]

I had the manual trim cable on mine which did not work, so I took the cable out and installed a turnbuckle on my trim tab on the elevator. I go out and fly to see which way I have to trim it. When I get back on the ground I make a few turns on the tab, then go fly agin. I adjust it to fly straight and level at cruising speed. I only have to make this adjustment when I put my ski's on and again when I take them off. Then if I need to tweek it, I use the flaperons for down trim and the trim handle for up. I just used a .25 spring from the hardware store and connected it from my trim handle to the control column. Simple, light weight and cheap.

Edited 23 Feb 2012 by Bandit

[High Country 69]

I had the manual trim cable on mine which did not work, so I took the cable out and installed a turnbuckle on my trim tab on the elevator. I go out and fly to see which way I have to trim it. When I get back on the ground I make a few turns on the tab, then go fly agin. I adjust it to fly straight and level at cruising speed. I only have to make this adjustment when I put my ski's on and again when I take them off. Then if I need to tweek it, I use the flaperons for down trim and the trim handle for up. I just used a .25 spring from the hardware store and connected it from my trim handle to the control column. Simple, light weight and cheap.

What did not work with the cable design, and which one did you use? I think that i could possibly just go with the rans wheel in front of the flap handle mounted in the center just off the floor and it should work just fine.

-Robert-

[Bandit 286]

The cable Avid sent was just a lawn mower choke cable I think. When you moved the trim handle the wire would just bow between the mounting points going back through the fuselage. Then it had to go through two 90 degree bends to get to the trim. It never did work. I think with a better cable this system might work, but the way I have it now is just fine.

[FoxDB 17]

I have installed the AeroVee trim kit as well. Attached are photos of my Kitfox 1 installation. I did end up changing to a lighter rear spring after I took the pictures. It seems to work well. I was able to remove the fixed trim tabs on the elevator and can now trim with the AeroVee Knob alone.

Dave

[efil 01 74]

I have a Rotax 532 so I'm pretty limited on power output (10 amps) so i am trying to make as much manual or self powered as possible to reserve the power for lights

-Robert-

i'm going with the 582 rope start in my C and plan to put a little battery on firewall to have radio and electric trim.

about trim tab versus string on stick, there a big safety difference for me, the tab can save you if the elevator command is broken, the string not.

[Av8r3400 1179]

I agree manu. That's the one thing that scares me in my Kitfox. If I loose the "Jesus" bolt on the elevator horn, I'm going to die. Period. With a trim tab you at least have a chance.

[High Country 69]

what trim setup would you guys recommend and how many amps does it draw. it seems that an electric system would be the easiest way to go I'm just still a bit concerned about the power draw.

-Robert-

edit: ok so i think the Ray Allen T2-7A Servo with .7" travel should work fine and only has .5 amp draw. Is this correct. If so this may be my ticket.http://www.rayallencompany.com/products/trimsystems.html

Edited 15 Mar 2012 by High Country