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Vernier Throttle for the RV-12

Dvalcik

Well Known Member
Sponsor
Just received the throttle for my EAB 12. I went straight to McFarland for the same one as the Vans throttle, except with the Vernier and Friction lock features. As I get closer to the first flight I will post my thoughts and how the throttle performs.
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throttle photo.JPG
 
RV-12-specific vernier throttle availability

Michelle Shelly at MacFarlane informed me that an RV-12-specific vernier throttle package is now available. This consists of their Rotax 912-compatible vernier throttle which has the cables pre-cut to that of the original throttle cable supplied with the kit, with the cable ends crimped on, along with a set of weaker throttle springs to replace the extra-heavy pull original Rotax-supplied springs.

P/N: MCRV12-T
$176.95

This does not yet appear in their on-line catalog.

Rob
 
Any experience with the vernier throttle?

Has anyone installed and tried the vernier throttle from McFarland? I don't like the idea of the weaker springs.

Regards,

Rafael
RV=8A flying and for sale
Rv-12 5 hours completed
 
After 10+ hours in a Mooney with a vernier throttle, I have to say that I hate vernier throttles. I found the throttle very unsafe. On takeoff, it was difficult to feed throttle in for take-off power without glancing down thus it became difficult to keep the airplane on the runway.

Landing had the same problem. Pulling the power to idle right before or at touchdown was difficult and the airplane would sometimes get pointed sideways. If the instructor asked for a go around on short final or right before touching down, that also was next to impossible to do without touching the runway or adding power in at the proper increase rate.
 
Vernier Throttle operation

After 10+ hours in a Mooney with a vernier throttle, I have to say that I hate vernier throttles. I found the throttle very unsafe. On takeoff, it was difficult to feed throttle in for take-off power without glancing down thus it became difficult to keep the airplane on the runway.

Landing had the same problem. Pulling the power to idle right before or at touchdown was difficult and the airplane would sometimes get pointed sideways. If the instructor asked for a go around on short final or right before touching down, that also was next to impossible to do without touching the runway or adding power in at the proper increase rate.

I have owned 4 Bonanzas, all with Vernier Controls. To operate without the Vernier, one simply pushes the center button and it operates push/pull. Looking at the McFarland design, I believe it operates in a similar way.

Regards,

Rafael
 
Has anyone installed and tried the vernier throttle from McFarland? I don't like the idea of the weaker springs.



Regards,

Rafael
RV=8A flying and for sale
Rv-12 5 hours completed

Guys the one for the 12 doesn't have a push to activate.  This new style push or pull the throttle or twist to fine tune the settings 

Best of both worlds 

From day one that is what I installed. Very smooth and responsive. I did install the spings and glad I did. I did transition training in an E-LSA RV12 using the standard throttle with the friction lock and no issues (the Vernier is just a little nicer setup). After 60 hours in my 12 I wouldn't switch, I love the Vernier.
 
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I've been flying with vernier throttles for over 40 years and love them.
If I need a rapid advance or retard, I simply hold the button in with my palm. Otherwise I can fine tune easily.

It's a matter of what you like.
 
Mel - the one for the RV12 doesn't have a button - it is vernier assist

From their website

Vernier-AssistTM Throttle Controls for Dual Carburetor 912/914 Series Rotax Engines
Innovative design allows a neat, clean installation without a clunky splitter box

McFarlane invents a new type of vernier engine control
This brand new type of control has all the fine adjustment benefits of an old style push-button release vernier control, with the simplicity, responsiveness, and jam-proof safety of a friction lock control.

Throttle Function No Text.jpg


Light weight and compact behind the panel
Safer - no vernier threads to jam!
Patent Pending US Pat. Application #13/110,632
These light weight controls use a patent pending drive mechanism. The new roller action vernier provides smooth, jam-proof coarse and fine adjustment without a release button. Coarse adjustments are made by pushing the knob inwards or pulling the knob outwards. Fine adjustments are made by rotating the knob clockwise or counterclockwise.
 
Now I'm really confused!

Is it just the friction lock that holds the throttle back counter-acting the springs, or is there a firm lock that releases when the throttle is pushed or pulled? If it's just the friction lock holding the throttle from moving, then I can't see how this is any better in keeping the springs from creeping the throttle up. One just gets the added feature of vernier adjustment, but would still have to override the friction to make course adjustments.

I'll call McFarland in the morning for a clarification.

Cheers,

Rafael
 
It works this way.

The McFarlane Vernier Assist Rotax throttle works this way. First you have to also buy, if not included, the McFarlane replacement Rotax throttle arm springs part number 6696. If you don't use the springs the Vernier Assist throttle will not work correctly. With the tension lock nut all the way tighten all this does is keep the throttle from creeping forward. It does not lock the throttle from moving. The pilot can still push or pull the throttle. At this point it acts like a regular throttle like on a C-172 or C-152/150. Also at this point if you wish to make fine adjustments all you have to do is twist the throttle to move it in or out very slowly. Hence the phrase, "Vernier Assist".
 
McFarlane Throttle installed...

I installed the McFarlane Throttle and also the springs that came with it. I found a couple of installation issues that no one else has mentioned so here is my experience.

First, the throttle installs in a 3/4" diameter hole so you will need to open the stock RV-12 panel hole to 3/4". After doing so, I found that there is not a lot of clearance to the bottom of the instrument tray for the larger retaining nut on the new throttle control.
P1040293-M.jpg


I had to file off the corners of the nice red anodized nut:
P1040294-M.jpg


And make a flat on the lock washer, too:
P1040295-M.jpg


After this shade tree mechanic work the throttle went in OK:
P1040298-M.jpg


The throttle comes with matching springs, no doubt important to the proper operation of this vernier setup. Seen here installed with a comparison to the stock spring:
P1040296-M.jpg


Once installed along with the matching springs, the throttle works very nicely. You use it much like the original by setting the friction as you like, but now it takes less friction. Then you can push or pull the throttle or turn the knob for small movements. It is really cool to turn the vernier and watch the throttle arms slowly move.
P1040302-M.jpg


It was raining at the airport today so I did not do a carb sync or fly the plane with the new throttle but I expect it to be a nice improvement in quality of flying, and I consider it a safety improvement as well. No more "fighting the machine", as my pal Bob calls it.

Tony
 
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Hey, "Shade Tree", you is 'da Best. Sorry I missed your, 'er, swearing session. After Monday, I will have rendered unto Caesar, and can resume doing my own thing. I'd like to watch/help you re-balance your carbs, etc etc.

Bob
N737G
 
We've got 10 hours or so on the new throttle cable (35 hours before the mod) and it's a superb bit of kit that transforms the engine handling.

Remember this isn't a vernier control in the normal sense. The vernier action is engaged by turning the friction lock, slacken the friction lock and it's a normal push/pull action that isn't trying to countersink itself through the instrument panel the moment your grip twitches :eek:

If you do the mod then you will not be disappointed and I would hope that Van's adopt this control as the standard issue part - even if it is a few dollars more.

Only snags were the clearance issues during installation that Tony detailed above.

Okay, so the carbs need setting up but that's worth doing periodically anyway.

Well done McFarlane! :)
 
Moving a hole

Instead of enlarging a hole concentrically, I have enlarged and moved a hole to the side using a file. I file the hole slightly under size, then final drill with the desired final size drill bit.
This same trick works on smaller size holes too. If the pilot hole is slightly off center, file it on one side, then final drill.
Joe Gores
 
Lazy engineer's approach

When installing my vernier throttle, after enlarging the hole with a step drill, I took out the screws holding the center panel in, allowing me to tighten the (unmodified) nut, being careful to tighten it such that the top face of the nut was horizontal. There was enough clearance to then replace the center panel, with the bottom of the panel serving as a secondary locking mechanism.
 
Review of Old Thread

I flew Jetguy's 12 with the MacFarlane and loved it. I have one to install on my 756TS plane, but standing between the wing and a whirling prop in my old age unsteady stance worries me. I can see no reason that I cannot measure the opening with a precision caliper, then adjust to repeat the previous measurements. Am I just doing wishful thinking, or is this feasible?
 
I flew Jetguy's 12 with the MacFarlane and loved it. I have one to install on my 756TS plane, but standing between the wing and a whirling prop in my old age unsteady stance worries me. I can see no reason that I cannot measure the opening with a precision caliper, then adjust to repeat the previous measurements. Am I just doing wishful thinking, or is this feasible?

If you are talking about taking measurements to make throttle adjustments normally completed while doing a carb. synchronization?

Yes, it is wishful thinking. No, it is not feasible.
 
I flew Jetguy's 12 with the MacFarlane and loved it. I have one to install on my 756TS plane, but standing between the wing and a whirling prop in my old age unsteady stance worries me. I can see no reason that I cannot measure the opening with a precision caliper, then adjust to repeat the previous measurements. Am I just doing wishful thinking, or is this feasible?

Don, you do not need to make adjustments with the engine running. Get someone to help you. You stay in the cockpit and take the readings on the Carbmate or the instrument of your choice, then shut down and have your helper make very small adjustments to the throttle lingages, and repeat the process. A few iterations and you are done!

BTW, have you made any progress with your medical/training issues?
 
I think I am about to make a major (to me) announcement about my woes.
Thanks for the advice on the adjustments, I have done many multiple carb adjustments on motorcycles. I have a gage set and had not thought of doing it that way. Not having done it yet, it still seems to me that duplicating what is currently synced would work. I defer to those who have actually looked under the engine cover though. I suppose there is not a good place to get a measurement.

Don, you do not need to make adjustments with the engine running. Get someone to help you. You stay in the cockpit and take the readings on the Carbmate or the instrument of your choice, then shut down and have your helper make very small adjustments to the throttle lingages, and repeat the process. A few iterations and you are done!

BTW, have you made any progress with your medical/training issues?
 
I suppose there is not a good place to get a measurement.
There is, but that's not all there is to it. The length and placement of the cable sheath will make a difference. You could be spot on at idle and totally off at higher RPMs. When I installed mine we were fairly close right off the bat, but not close enough to go flying. The adjustment gave us fits, but that turned out to be a simple air leak. When I wrapped zip-ties around the hose connections for the Carb Mate and cinched everything down TIGHT the adjustments were a snap.
 
I don't think I was quite clear. Obviously the idle adjustment will not be touched, no need to. As shown in the photo, if the arms are each put back EXACTLY in the position they were when I started, then it absolutely has to be exactly as balanced as when I started. I plan to take the measurements here on each carb, then duplicate it with the new cables. I think I will file a small groove in the top of the throttle arm for a reference point to measure from.
1zd8aqc.jpg
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I don't think I was quite clear. Obviously the idle adjustment will not be touched, no need to. As shown in the photo, if the arms are each put back EXACTLY in the position thy were when I started, then it absolutely has to be exactly as balanced as when I started. I plan to take the measurements here on each carb, then duplicate it with the new cables. I think I will file a small groove in the top of the throttle arm for a reference point to measure from.
1zd8aqc.jpg
[/IMG]

Don,
You sound determined e convinced you have it figured out, so at this point, probably your best approach would be to just do it and tell us how well it worked.....
 
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