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RV4 manual to electric elevator trim

gggflyer

Active Member
I purchased a flying RV4 with manual trim. If I want electric trim, would it be easier to just buy a left elevator and electric kit from van and start from scratch or retrofit into existing elevator.

Also has anyone converted manual flaps to electric? If so is it a huge ordeal. I didnt build it so these would be my first intro to the actual building and guts of the rv4.

Thanks

George
 
I would suggest that you leave the manual trim in and also the manual flaps. Fly the plane for several hours and you will be very comfortable with them. The electric trim is not as easy and as smooth to use as the manual trim. The nice thing about manual flaps is that it is almost impossible to put them on at too high of a speed and you can ditch them faster than electric also.
 
Why on trim? Flaps maybe.

The manual trim works fine, would just leave it. Electric flaps gets rid of the handle, easy to change out, if you can get the parts/kit from Vans.
 
I'm going to disagree with the other two. I absolutely hated my manual trim and flaps. Flaps, get the Vans parts and move forward. I did a custom under floor flap system that I love, but takes way more fabrication than most people are comfortable with.

Trim. You do NOT need an entire elevator. You can reskin the inboard portion and add the servo. I originally put the servo on the horizontal deck of the fuselage. I felt it had too much slop there and moved it to the elevator. I'll get you pictures in the morning.
 
I second the electric flap kit from Vans.
As for trim: I’m about to ditch my manual trim. I want the trim on my stick grip where it belongs. So I’ll be fitting a servo to the end of the stock manual trim cable. It will be housed below the throttle quadrant. Keeping the cable and trim tab as is seems to be the simplest way forward.
 
What I did

I built my -4, with electric flaps ,aileron and elevator trim. My elevator was already set up for manual, so I made some slight changes to the VANs kit, and it was easy cheesy. I have the MAC stick with flaps, elevator and aileron trim all on it..never have to take a hand off to trip or set flaps, absolutely love it. There are several ways to convert to electric flaps, the VANs kit comes with weldments and all the bits needed.The actuator is under the floor with some well thought out linkage.Other conversion use a vertically mounted actuator in the right or left sidewall attaching directly to the existing weldment, and search the threads for pictures on here.I used the VANs aileron trim kit, but built in a tab rather than the hinge half extension tab. I have attached a picture of the elevator and aileron tabs.
 

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Yes, it’s fairly easy to convert from manual to electric. The hardest part is installing the actuator and hardware. Vans sells the conversion kit, but you can get the plans and fabricate everything yourself.
 
Another approach to consider

Building Rocket lite. I utilized the RV8 roll trim kit. It is spring bias type that connects to the control column. No mods to control surfaces required but does require some sub floor work obviously. Could probably implement in less than a day depending on your choices. Just passing on another option to cloud your thoughts.
 
I reskinned the inboard section with .025. 1 because I had a bunch, and 2 because I wanted a little extra rigidity. The skin doubler / platenut mount was a copy of the Vans design with some minor tweaks to fit the -4. The Servo mount / cover plate was an exact copy of the Vans. If you buy the RV-7 or -8 electric trim kit it should have everything there.

Pictures as requested:

Original cut out for the manual trim cable.
IMG_20200429_135959.jpg
Rivets drilled out giving access.
IMG_20200429_140004.jpg
New skin with doubler riveted in.
IMG_20200429_223805.jpg
Another view.
IMG_20200429_223810.jpg
 
Converted my rv4 to electric trim and flaps so I had it all on the stick. I just removed the heavy manual trim cable and mounted ray allen servo under vertical stabilizer with a small pushrod to trim tab.
 
IMHO I would not bother with the trim. After flying a few 4's I can say, I prefer the manual trim over the electric. I would do the flap upgrade. It's a weekend's worth of work with the vans kit.

If you do decide to do the elevator trim I would consider mounting the servo in the aft fuselage and using a smaller cable. See the website below for a few pictures.

http://romeolima.com/rv3/rv3works/airframe/airframe.html#Fuselage

https://www.aircraftspruce.com/catalog/pnpages/05-16936.php

This is my plan. But good luck getting that actuator cable from Aircraft Spruce. It's been out of stock for 9 months, they told me that delivery would be 10 weeks for one. 14 weeks after ordering, I cancelled the order. I can get one made at the local marine store for 40% less.
 
I will be doing a similar thing on my current RV6 build. Keeps some weight out of the elevator, and the left elevator counterweight. I’ll either use a custom made cable, or pushrod.


IMHO I would not bother with the trim. After flying a few 4's I can say, I prefer the manual trim over the electric. I would do the flap upgrade. It's a weekend's worth of work with the vans kit.

If you do decide to do the elevator trim I would consider mounting the servo in the aft fuselage and using a smaller cable. See the website below for a few pictures.

http://romeolima.com/rv3/rv3works/airframe/airframe.html#Fuselage

https://www.aircraftspruce.com/catalog/pnpages/05-16936.php
 
Keep the manual trim - you will thank us in time!!
Keep the stick top free from anything except a PTT!

Van's will sell a kit to convert to electric flaps.
Pete
 
We make an under the floor flap kit for the F1 Rockets and F4 Raiders. I see no reason that it wouldn't work on an RV-4 (and maybe the RV-8) with some trimming.

The system is as described... completely under the floor, behind the rear spar, and eliminates the normal RV-4 flap weldment that is above the floor.

I'm looking for ONE RV-4 builder to try it out to see if it works as expected. The preferred builder should:
  • be an experienced fabricator, not afraid to try new things, and competent enough to handle snafus
  • have a flying RV-4, or one that is far enough along to completely install and function test the flap system, including the flaps on the wings
  • be someone who understands that the system might not work for an RV-4
  • be aware that new holes would need to be drilled, including for the flap pushrods
  • be able to take notes and photos for others to use, or for mods to be made
  • be able to complete the job in a reasonable time so that others might be able to follow along afterwards

Our UTF flap kit includes everything needed to install in an F1 Rocket or F4 Raider (I've never heard of a Rocket Lite) including the linear actuator. Limit switches and wiring are not included.

Contact Vince at [email protected] No PMs please.
 
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