AndyRV7

AndyRV7

Well Known Member
I am interested in possible modifying these things on my plane. For the flaps I currently have a momentary up and down switch. I think I would like the ability to have a momentary down control with a one-touch up control. Would I need some type of flap controller to do this. Any drawbacks to this type of capability in the real world?

I have manual elevator trim and would love to be able to see what trim setting I have at any given time. I have a GRT Sport efis but not trim indications of any kind. What is the simplest way to go about getting a trim position indication in the plane, or is it impossible with manual trim?

One other unrelated question. I recently ordered several sizes of countersunk-head screws from Vans with the intention of having some extras for the times I might strip one or two while removing my cowl or wheel pants or the like. All of the hardware came in a bronze color or similar instead of the steel colored screws I currently use on the plane. Should this be a concern? What if I wanted steel colored screws, where could I get those?

Thanks! Andy
 
FPS

Hi Andy,

The Flap Positioning System in the link below works well and has a one touch flap up position. I find it greatly reducing my workload during go around compared to holding the flap up switch until they were retracted while trimming the nose down etc. Install on an RV10 was easy, 3-4 hours to remove the tunnel covers, install, run wiring, test ops, and put back together.


http://www.showplanes.com/index.php?app=ecom&ns=prodshow&ref=FPS
 
Another horray for FPS, although it is not the simplest wiring specially in an already flying plane. I have had so far 500 hour of flawless operation with it and love the FPS plus where your trim tab gets set accourding to your flap position.
 
For the countersunk screws you are mostly dealing with AN507-6R8 and AN509-8R8. The ones that Vans sent you are yellow because that is the color of the cadmium plating on the carbon steel. If you want the stainless steel screws, they will be bright silver as you mention.

The equivalent stainless screws can be had from Vans or Aircraft Spruce.

For the stainless equivalent of AN507-6R8, order AN507C632R8 from Vans or MS24693-C28 from Spruce.

For the stainless equivalent of AN509-8R8, order AN507C832R8 from Vans or MS24694C5 or MS24693-C50 from Spruce.

For the 8-32 thread size, there would be a slight preference toward MS24694C5 because it's a structural screw, whereas the MS24693-C50 and AN507C832R8 are listed as a non-structural screw. Structural means there is a portion of the shank, directly below the screw head, which is not threaded so it's stronger. For the 6-32 thread size, there is no structural screw equivalent listed in stainless.

In general, stainless screws are not as strong as carbon steel screws. But we're mostly not using them in structural applications (except maybe mounting the fuel tanks to the spar).
 
Last edited:
Thanks guys. I saw both of those flap systems before I posted. It's good to know others are trying to solve the same problem.

Kurt, excellent education on the hardware. Much appeciated!

Anyone have any feedback on the trim position problem?

Andy
 
AndyRV7 said:
I am interested in possible modifying these things on my plane. For the flaps I currently have a momentary up and down switch. I think I would like the ability to have a momentary down control with a one-touch up control. Would I need some type of flap controller to do this. Any drawbacks to this type of capability in the real world?

Thanks! Andy
Click to expand...

Andy, possibly the easiest solution for what you propose is just to add an up-limit cutout switch to the flap circuit. I positioned mine in the flap actuator enclosure on the floor such that when the flaps reach the full up position the actuator arm makes the limit switch which turns off the flap motor. The circuit is rearmed as soon as you move the flaps down again. Of course, you also need to replace your flap switch to the ON-OFF-(ON) type.

I wrote a blog post (with pictures) on this issue here which goes into more detail if you like.

Actually, I think this is a safety issue. When you execute a go-around or shoot a touch-and-go, you shouldn't be holding the flap switch up in my opinion. In my case, I just flip the flap switch up and the flap motor turns off when the flaps reach the UP position. Many who have the momentary switch DN and the switch position that stays UP have told me that they have forgotten and left the flap motor running the entire flight--not good. The limit switch solves this problem.
 
AndyRV7 said:
I have manual elevator trim and would love to be able to see what trim setting I have at any given time.
Click to expand...

Andy, are you still kind of new to flying an RV?

The only reason to really ever physically see the pitch trim position on any airplane is to set it for takeoff. After that, trim is changed in the amount the pilot needs based on what they feel. The smoothest way to do that is to use the stick to set the pitch attitude that you want, and then begin adjusting the trim until the required force on the stick goes to zero.
Having said that; with experience, the position of the knob on the pitch trim control will tell you all you need to know (if you desire that info).
My personal RV has manual pitch trim (which I prefer over the electric in many ways). I can tell just by feel where the pitch trim is set.
 
I have about 60 hours but take-off is the only time I care. Landing pitch trim is pretty significant on takeoff roll. I'd rather set it to neutral and have to use much less force on the stick to lift the tail. All the extra force needed now makes it more difficult to keep from accidentally adding some aileron as well.

Generally, it takes about 4 good twists after the wheels are up to trim out the aggressive nose up attitude. Maybe that's 2 full turns or so. I considered trimming in the hangar once to see how many turns it takes to get to neutral, but I would rather have a consistent starting point before I add power on the runway.

A trim indicator seems logical but looking for ideas.
 
The amount of nose down trim ever needed in any of the two seat RV's is small compared to the amount of nose up trim, so most of the trim range is tab down.
I have my trim system adjusted so that the tab is in the trail (neutral) or just slightly down position when there is about a fingers width gap between the base of the knob and the body of the control.
This allows for about 30% of the travel to be nose down trim and 70% nose up trim. In simpler terms, when you move the trim tab through its entire range of travel there should be about a 2:1 ration (maybe even a little more) of down travel to up travel.

The finger width gap allows for pretty reliably setting the trim for takeoff each time. In reality, being able to set it very precisely is of little value because the required setting is slightly different for every take-off because of the variability in CG position. Even then it is rare that I have to turn the knob more than 1/8 turn shortly after take-off.
 
Interesting approach. I am going to pay more attention to my settings at the knob now to see what I find. Thanks!
 
Check this thread:

http://www.vansairforce.com/community/showthread.php?t=7912

It can also be simplified by relocating the limit switch in series with the flap motor and installing a 10 Amp diode across the limit switch. The switch breaks the current flow in the up direction when triggered, but allows current to flow through the diode in the down direction.

I've used both systems... the first in my RV-9A, the second in my HR-II.

Very reliable either way.
 
Flap Position System

I have a used FPS. Low time. It worked very well. New from Vans is $225. I haven't listed on eBay yet. Will let you have it for $180. Put a little tab of 1/4" colored tape a few inches long where it will show at each flap position and it makes it easy to see where you are if you get distracted.
 
You must log in or register to reply here.