Author: redstick

We have decided to discontinue the RV Flap Actuator that many have installed in their single-digit RVs, the RV-6, -7, -8, and -9. We are now recommending the RV-10/-14 actuator for all models except the RV-8. This newer actuator will now be renamed the RV Max Flap Actuator.

There are several reasons for doing this. Although there are hundreds of this actuator presently in RVs, we have had a few that will spontaneously retract–typically from full flaps back to about half flaps–for no apparent reason. We have termed this phenomenon “blowback.” It has occurred in about 3 actuators to date that we know of. We have had the factory look at an affected actuator and they have not seen any mechanical problems so our conclusion is that some actuators that are overly lubricated can be forced up. This would seems to be impossible given the nature of the jackscrew operation, but apparently in the case of over lubrication, it is possible to start the motion of the jackscrew by applying a force against the actuator. We had one customer disassemble his actuator and removed some of the lubrication and reported back that the actuator is operating much better. We have had this actuator in our own RV-6 for several years now without any problems of any kind.

Since we introduced the RV-10/-14 Actuator several years ago, we have sold many (over a hundred) to owners of those two aircraft. Given that the RV-9 wing and flaps are very similar, we installed one in an RV-9 build some time back and have had a great deal of success with it in the RV-9. We have since installed a few in RV-7s. We have concluded that this actuator works very well in the single-digit RVs. Additionally, this actuator is much more robust than the previous one and although about $50 more in cost, a much better value considering the high quality of the unit.

Due to supply chain issues, it is becoming more and more difficult to keep both actuators in stock. Going to just one actuator will greatly simplify our logistical problems and help us keep more of the RV Max actuators in stock.

Unfortunately, this actuator is probably not practical in an RV-8 due to its increased length and bulk. It is slightly longer and wider and weighs about a pound more than the older units.

We will soon be introducing our new RV Flap Actuator, which for some folks will be a big improvement over their current flap motor.

Although not a direct replacement, only minor modifications are necessary either to an existing installation or if building a new installation.  Our Installation & Operating Instructions are available for download and printing here.  We found that the installation in our RV-6 was relatively simple.  We did order a new flap motor channel from the mothership just to facilitate the changeover, but you could modify the one you have.  The majority of the work involves making a couple of new brackets out of 1 1/2 x 1 1/2 x 0.125″ 2024T3 angle.  The actuator is a little over an inch longer than the stock one, so you have to adjust for that.  We were able to move the attach point back about an inch because the new brackets can be made shorter—and the other 3/8″ or so was adjusted for in the flap links, which you may be able to adjust with the rod ends.  In the extreme case, you may have to make up a couple of new links.

We have been operating our RV-6 with 3 different prototypes for over 6 months now with great success.  The nice thing about this actuator is that it stops completely at either extreme of the stroke.  So when you get to full flaps, the motor stops—likewise for flaps up.  The motor does not keep running, so it is not necessary to have a spring-loaded switch to operate the flaps.  The other nice feature is that the actuator contains a position-sensing potentiometer inside the housing so that you can wire directly to a flap indicator or to your EFIS flap gauge.

We had these actuators made for us by a very reputable manufacturer to our specification.  We have every confidence that these units are plenty robust and should last a very long time.  We feel that this actuator will solve the “migrating grease” problem that some of the stock units experienced.  It is also not necessary to do the safety wire bulletin required in the stock units because the rod end does not rotate.

About the only negative we found was that these units are slightly longer (about 1.375″) and slightly heavier (about 9 ounces).

We do not have experience with its installation in any of the other RVs besides the RV-6, so your mileage may vary.  We would appreciate hearing from any customers who install our actuator in some of the other RVs so that we can relay your experiences to others. Here is a photo we took during the modification of our RV that shows the two units side by side.

And finally, compare the price of this actuator with the $460 cost of the stock actuator!

We were getting a few requests for separate inputs on our Ultimate TRB so that you could use a speed controller for the trim functions.  So we went ahead and modified our top of the line TRB so that you could have discrete voltage inputs for each function on the board.  We also added spike suppressing diodes to the relays.

In keeping with the KISS principal, we had designed the Ultimate TRB with just one voltage input.  This would probably be fine for a simple VFR airplane.  But for a more sophisticated airplane, you would probably want separate fused inputs.  That way if you had a flap problem, for example, and popped the CB, you wouldn’t lose your trim.  Or if you had a runaway trim situation and had to pull the CB, you wouldn’t lose your flaps.  All valid points.

These modifications are a major improvement to out best-selling relay board. We strongly believe that this relay board is the best choice for the homebuilder and will provide years of trouble-free service. We use them in our own airplanes and have yet to experience any faults or failures.

We also had to modify the test module for the separate inputs and added the three switches you see here so that we could isolate each function on the board.  Every TRB we manufacture is thoroughly tested with actual in-flight loads.

NEW! Beginning in September 2016, we began including spike suppressing diodes on the PCB for the relays, which should help increase the lifespan of your controlling switches (grip switches and flap switches), and will also minimize spurious EMF emissions caused by an inductive voltage spike arcing when switches are opened.

 

I’ve been flying RVs for 22 years now and something has always bothered me about the electric flaps. Don’t get me wrong, I love the RV flaps. It’s just that I get tired of holding the flap switch up when I’m on a go-around or when shooting touch-and-goes. So, if you’re like me, you probably listen for the telltale rumble the flap motor makes when the flaps are fully up. Either that or you glance out at the wing to see if the flaps are up—or both—and then let go of the switch. A distraction? Definitely!

Not to mention the safety aspect of messing with the flaps while you’re trying to add power, talk on the radio, clear for traffic and ask for a closed pattern, etc. And lately I’ve gotten into the habit of taking off with about 15° of flaps to save on tire wear.

Wouldn’t it be nice to just flip the flap switch up after takeoff and forget about the flaps? OK, now you’re in a nice safe climb or on downwind, go ahead and glance down at the flaps, make sure they’re up, and then, and only then, reposition the flap switch to neutral. Or just leave the switch up. You won’t hurt a thing.

Here’s another safety issue: I’ve been talking to some guys who have the flap switches on their Infinity grip. They mentioned that on occasion they would takeoff and flip their flap switch up and forget about it only to discover later in the flight that their flap motor had been running the whole time! I’m in favor of the ON (up) position on the flaps switch, but if you’re going to do that, you definitely want to add an up-limit microswitch to the circuit!

So, I’ve just developed a prototype kit and have been testing it in my RV-6—and I like it a lot! In keeping with the KISS principle, the kit consists of the bare essentials: a single pole double throw switch (ON-OFF-(ON)), a flaps-up limit switch, and a simple flap relay PCB board. This replaces my old DPDT ((ON)-OFF-(ON)) clunker in the panel. So now instead of spring-loaded UP and DN, the new switch stays UP and spring-loads DN. The power lead doesn’t go through the switch anymore, thus the flap amperage isn’t going through the switch, and in theory anyway, the switch should last longer.

The key to this mod is the Flap Relay Board. The flaps-up limit switch will not work with the old DPDT switch as wired. Maybe you could find a way to make it work, but by far the simplest and best method in my opinion is to use the reversing relays like the ones in the Flap Relay Board. Especially for you Infinity grip guys who don’t need the flap motor amperage running through your grip! This way, there’s just a tiny bit of current (about 33 mA) flowing through your flap control switch and through your up-limit microswitch.

So you pull the old switch out of the panel, make a small modification to the wiring, find a place to install the limit switch, mount the Flap Relay Board (FRB) in the flaps enclosure, wire the new stuff up, and you’re ready to go. I think you can complete the mod in a day.

The attached photos are of the installation of the kit in my RV-6. There are slight differences in all the RV models, so it may be necessary to take a slightly different approach in your particular airplane.

I don’t know why it took so long for me to make this mod. This is definitely one of the neatest upgrades I’ve done to my airplane. I know a lot of you have already done this on your own airplane and therefore I’m sure you are enjoying the benefits. For those of you who haven’t, here’s an easy way to accomplish this hugely worthwhile mod!

So, I put the kit together and am introducing it as a new product which you can order here on the site. I have kits available now for immediate shipping.

Note: I was able to pull the flap-shaped lever off the old switch and used it on the new switch—see last photo. I made this lever out of a solid chunk of aluminum and worked it on the disk sander and scotchbrite wheel, then had it engraved.

 

I finished up my Simulator for the new Ultimate Trim Relay Board and thought I would post some photos. I think it illustrates just how simple it is to wire two grips (with all the bells and whistles) using this hub concept—where all the wires from the grips go to the “input” D-sub connector and the “output” side is the gateway for all of the grip functions. Every one of the new relay boards gets a workout on the Simulator before it gets shipped (click on photo for enlarged version).

I have been getting excellent feedback from folks who have bought the relay boards. I wanted to emphasize that every relay board that I sell gets thoroughly tested before it gets shipped.

The flap actuator you see on the Simulator is an actual Usher Industries actuator as sold by Van’s Aircraft. I have done some testing with the flaps on my RV-6 to try to determine the amperage load during flaps operation. On the ground (or unloaded), amperage draw is slightly less than 1 amp. In flight, and within airspeed limits for flaps operation, amperage draw going down is between 3 to 5 amps, peaking towards the end of the cycle. It’s kind of hard to read the amperage because it varies so much as the flaps are moving, but on average the maximum load seems to be as flaps approach full down, and that’s about 5 amps or less. So I estimated that it would take about a 10 pound pull on the flap actuator to simulate (approximately) the load on the flaps in the airplane. I found a door spring, which you see here, that gave me about 10 pounds of force at 5″ of extension (flap actuator travel is 5 inches). The result is that I get almost the same amperage indications on the simulator as I do in the airplane, perhaps a little more on the simulator.

 

I used two old RC servos that I modified and loaded properly with resitors to simulate the electric trim servos we use on the RVs.

As it works out, this test rig will also serve nicely as a demonstrator at fly-ins, etc. Hope to see you with the Simulator someday soon at a fly-in somewhere!

And here is a photo of the original test equipment that I use for the smaller relay boards (lower right).

Anyway, I have trim relay boards available for most, if not all, grip configurations, so if you are approaching that phase of your build, please check out the web site and consider giving one of these a try.