SMO

SMO

Well Known Member
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I am wanting to install a Vans quadrant in place of the push/pull controls on my older RV-4. I will install it in a position similar to that in the picture below, and want to keep my manual trim. For others who have done this how has it been accomplished?

The picture below shows some kind of trim wheel installed - does anyone know what parts this requires? The wheel seems kind of small - not sure how easy it would be to use.

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Elevator Trim?

Thanks Steve, that helps for the mounting. What about the elevator trim? The quadrant would interfere with the elevator trim lever. Did you use electric trim?

I want to do exactly that but keep my manual elevator trim, just not sure on how to make these two (trim lever and quadrant) to live together in harmony!
 
My setup is exactly the same as Steve's is Mark (pretty standard) and the elevator trim lever is the tall one at the back. Because it sits up higher it does not interfer with the throttle or carb heat. I like the setup because all 3 are close to one another and on approach for example, you can adjust both throttle and trim together with one hand... very handy!

Cheers
 
SMO said:
What about the elevator trim?
Click to expand...

Mark, I went for the electric trim. My logic for that is that it is lighter. I have a thing about weight and I think it is a particular issue for an RV4. It works really well, but I do have a speed control in the circuit which is driven by flap position. (The -9a I had was hard to trim without a speed control.) So my trim is on the top of the stick.
 
Manual trim photo

Mark,
Not quite flying yet so as you can see, the engine control cables aren?t installed. My system design provides exactly the same leverage and travel as per the plans. When the empennage was stalled on the airplane it worked great. The pivot point is the lower bolt in the second photo. I can adjust the friction independent of the throttle quad. I played around with several ideas and finally settled on this. Simple, adjustable, low parts count.

 
Okay, I get it

So make a bracket that holds the quadrant an inch or so from the fuse and mount the quadrant low enough so the trim lever extends well above the throttle, passing through the bracket.

Thanks for this workable solution, I believe I can do that quite easily.

Would also be interested to see if anyone has a trim wheel or knob solution (I find it difficult to make fine adjustments with the stock trim lever). Ideally I would like a wheel sitting parallel to the fuse, driving a worm gear to move the cable back and forth. Just don't know where to get such hardware.
 
Exactly!

Thanks Steve. That is what I am looking for. I have sent a email to Dirk as well as a large salvage yard to see if I can find a similar "Piper" mechanism.
 
I now have electric trim

I originally installed the manual trim per the plans, and then mounted the quadrant on a bracket made from 3/4 x 3/4 angle that was mounted to the bulkheads and about 1/2" away from the fuselage wall. The trim handle extended above the quadrant. I really liked it.

For the last couple of years I have gone on a weight reduction spree which included going to electric trim. This item is especially significant becuase it is almost all aft of the CG, and most guys who fly the 4 will tell you it is nice to be able to put a couple more pounds in the back.

So the pro's of manual trim are that it works better than electric, very intuitive, and ieasier to get the trim set more accurately quickly. Con's are weight. I'm sure whatever you end up doing you will be happy with it.
 
Convert your manual elevator trim to electric simiply

Mark,

Here is another approach to handling your trim, leaving the push/pull cable in place and adding a servo.

I purchased an RV-4 this spring and converted manual to electric and never touched the elevator and it works fine.

Pull your manual trim cable back out of the side bulkheads including bulkhead F-408. Now coil the excess cable and drill a hole in the bottom of bulkhead F-408 then pass the cable with one nut attached through the hole you drilled and secure it with the second nut after pulling it through. Now make a small shelf to which you attach your electric servo. The position of the shelf is to provide you with full range of travel for up and down trim. Install a clevis on the end of the manual cable, put a # 6 rivet into the 3/16 holes of the clevis and smack the rivet to expand in the 3/16" hole, cut away everything other than the expanded rivet portion in the two holes. Now redrill the aluminum rivet portion in the holes to accommodate a 1/8" clevis pin that goes through the 1/8" hole in the electric servo. Just wire it per instructions and put your trim switch on the panel or stick and your good to go without having to retrofit the left elevator with a servo inside. Works great for me and saved a lot of time.

I also used to live in B.C. Sorry about your recent avalanche problems and loss of life.

Jake
 
Interesting Option

Jake,
I thought about an electric trim but didn't want to do the work on the elevator. Do you have any pictures of your setup? Which bulkhead is the F-408? Where did you put the shelf? What servo did you use? You mention coiling the excess cable - did you cut the cable?

Thanks for your thoughts on our recent tragedy. There are not many people in this valley that are not affected in some way.
 
Trim conversion to electric

Mark,

I thought I had taken some pictures but can't find them on my computer.

I can tell you that to change manual to electric, this method that I came up with, is in my opinion, the easiest way to go. The servo has plenty of power to push and pull the cable that terminates at the trim tab.

The trim servo you would want from Van's is part #ES MSTS-8A, which is the 1.2 inch stroke servo. You can go on line to check the price, it is near $300.

You do not alter the existing cable in any way. As I said previously, you pull the cable back through the bushings to and including bulkhead 408. 408 is the bulkhead after the one that the the rear seats rests against. It's the bulkhead that closes off the tail cone from the baggage area.

Besides purchasing the servo the only other part you would need is Van's nylon clevis, part #HW Nylon Clevis 1032. If you use that clevis, I think the holes (through the clevis) where you insert the clevis pin are 1/8", so you don't have to plug the 3/16" holes in the metal clevis I used. The hole in the servo that you attach the clevis to is 1/8".

If this method truly interests you, I will remove the necessary parts in my baggage compartment and take pictures for you. I don't want to go to the trouble unless this is the way you will go. All parts you need to do this should be in your scrap bin, besides the servo and clevis.

You can contact me directly at "[email protected]" .

Jake
 
Got it

Thanks for this Jake. No need to take pictures. This does sound like the simplest option - problem solved.
 
The Long Run...

Great ideas, but what happens when it breaks in BFE? You're stuck on the road with a fixed trim tab. If you don't fly much and only take occasional cross countries, no worries. (I did ALOT of cross country, a long ways from home. I kept a spare prop, mags, alt and starter in mailing boxes at home for my neighbors to send me in case I broke down on the road.)
I installed a simple quadrant and a manual trim lever in my RV4 which allowed pinkie adjustments while holding the throttle. I considered electric trim but found the manual trim to be simple, effective and bulletproof! I used a piece of angle to move my quadrant away from the fuselage side to allow room for the trim lever on the inside. I only had one quadrant lever, throttle! I put my mixture on a vernier under the panel which allowed a much finer mixture adjustment and alternate air next to it with a T handle. I also had manual flaps and loved them!
Having flown -4's with electric trim and flaps, I chose manual for my type of flying. 1500 hours were flown with no worries.
My Rocket has 3 axis electric trim and flaps. I have already had to change one servo after 300 hours, not fun when you are on the road.

My Dos Centavos..

Smokey
HR2
 
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