Ray Allen trim systems questions

Pilottonny · #1 03-30-2008, 03:17 AM

Hello Guys,

I searched the forums but could not find any answers:
Two questions on Ray Allen Trim systems:

Is there need for high/low speed on the aileron trim? The system looks kinda simple and not so precise, with the springs, but do you want low speed at cruise speeds and high speed in the pattern, or just wire it directly and have high speed operation only?

Does the Ray Allen speed controller need a diode on the outgoing lead, if I have a speed-switch which puts 12 Volt power on that lead? In other words: I have a limit switch on the Flap actuator arm, that switches power directly to the servo or via the speed controller, depending on flap position. In the case that there is power directly on the servo, the speed controller gets 12 Volt on the ? wrong end? ! Is that a problem? I am not sure how it works, maybe it has an internal diode?

Thanks in advance for your input.

Geico266 · #2 03-30-2008, 06:16 AM

I think the two different speeds would be real nice to have. At high / cruise speed just a tap on the trims can be too much.

Can't help you with the diode thing.

Rick6a · #3 03-30-2008, 09:29 AM

Quote:

Originally Posted by Pilottonny

......Is there need for high/low speed on the aileron trim?

I can only respond with my experience using the older electric trim that sports a hinge half mounted on the trailing edge of the left aileron. The servo speed is quite adequate through all flight speeds the way it is. Fast or slow reponse time is just not an issue. Besides, roll trim is not needed anywhere near as often as pitch trim and is mostly used to offset a fuel imbalance. I have found myself droning along without noticing the very subtle changes in stick position that causes the stick to lean or bias in one direction or another to maintain a wings level attitude. Often my cue is when the capacitive fuel level gauge starts blinking an alert and that occurs with about 4 gallons difference between the tanks, prompting me to switch. A minor trim adjustment is all that is required to straighten the stick to vertical and you are good until a significant fuel imbalance occurs again. If you are the type to constantly switch tanks, you don't even have to do that. But getting back to your original question, I believe a speed controller is a waste of money and complexity when coupled to an electric roll trim servo. On the other hand, I consider a speed controller mandatory for electric pitch trim purposes as the servo speed is too fast for high speed flight and you can find yourself "chasing it." It is better to slow the servo speed down. But optimized for high speed cuts both ways. As you slow down, you will have to depress the button for a longer period of time to affect a suitable trim condition. The slower you go, the longer you will have to depress the button. But for me at least that is a non-issue of even smaller consequence because the trim adjustment is made via the china hat atop the Infinity stick grip and my hand and thumb are there anyway. I tend to dismiss some of the stuff I have read about a possible runaway trim condition in RV's at least in VFR conditions. IFR is another thing and I cannot comment. You can overcome maximum trim deflection although the stick force to do so is greatly increased. I suppose the physical strength required to do so is open to debate but what I consider a nuisance in increased stick forces some others might consider to be a daunting force to overcome. YMMV.

groucho · #4 03-30-2008, 09:34 AM

I have Ray Allen elevator & aileron trim servos & they both work great without any two-speed setup. Love 'em!

mcphersn · #5 03-30-2008, 06:22 PM

Not trying to steal the thread, but the only trouble I've had with my trim (on the stick) was when the "expert" who was giving me my bfr took the controls and accidentally put down full flaps at max cruise. Thank Van for a design that can take unbelievable abuse...

Miller McPherson
RV-6

RVG8tor · #6 03-31-2008, 09:02 AM

This can happen to the best of us. While getting my first ride in an AT-38 the instructor was to demo some handling with the gear down. He misread the airspeed as 250kts when we were at 350kts. I spoke up when I realized he was moving the gear handle but it was too late. Of course we RTBd, but the inspection revealed no damage.

Cheers
Nemo

smithhb · #7 04-01-2008, 06:48 AM

I have the same setup (still building) and do not plan on using a speed control for the aileron trim. I feel that if it is too fast, I can always add a speed controller later.

I also am using the flap actuator to trigger a limit switch. http://www.flightinnovations.com/fus...troller_Switch

There is no need for a diode to the speed controller as the speed controller is actually a potentiometer and reduces the voltage for the servo. You would only use a diode if you are planning to use the Ray Allen rocker switches. They cannot handle 12V.

Pilottonny · #8 04-01-2008, 01:08 PM

Bret,

I spoke to Ray Allen Comp. yesterday, because I did not get a lot of response on the question.

They told me that the controller is actually an electronic device not just a pot.meter! (why would there be a ground wire if it was just a resister?). They suggested a diode to keep the 12 volt off the outgoing line.

So I hopped down the local electronics shop and bought a diode! After swapping the teeny-weeny-tiny thing they wanted to give me (14 V/1A), for a more robust one (1000 V/3A), I paid a stunning 25 cent ! This was certainly the cheapest part I bought for the plane!

Problem solved! Thanks for the input anyway.

kentb · #9 04-02-2008, 09:11 AM

Don't understand why someone tried to steal your thread with "flap" accidents, but to get back to your question about the trim.

I don't have two speed on the aileron trim in my 9A. Don't think that it is needed. I do have it on the elevator with the two speeds with the switch on the flap position controlling it. If you don't use two speeds it will be touchy when you are going fast.

Kent

Pilottonny · #10 04-02-2008, 10:37 AM

Kent,

I will be going for the "2-speed" on the elevator and "one-speed" on the aileron trim. Thanks for your input.

It's strange how some questions get answered quick (and with a lot of answers) and other questions don't get answered at all. I asked for max. stick travel in an other thread twice so far, not one answer, hm.... strange.

Regards, Tonny.