Flap Control Revisited

[JLuckey]

I have searched for a flap control system that mimics the flaps on the C-172 I learned to fly in (long time ago). Features like pre-set flap positions & some indication of current flap position. In the good-old 172 it was done w/ micro-switches & speedometer cables. (but I don't want that kind of hardware in my RV-7)

I couldn't find one so I mocked-up my own.
Here's a 3 minute video that demonstrates its functionality: http://www.youtube.com/watch?v=OcBvmL-FxYQ

I'm looking for constructive feedback as to anything that is missing from the design or ways to improve it.

Your input is much appreciated.

[kevinh]

My 1st instinct was to say use one of those microswitches and look out the window. But you've made me change my mind - really slick and in the true spirit of Experimental (capital E) aviation.

[RatMan]

Not sure about the -7 but in the -8 the system works exactly oppiosite of what you have shown. When the arm goes up the flaps are raised, when the arm goes down the flaps are lowered.

Still, pretty cool and wouldn't take much to reverse the action.

I have found that I only use three flap positions really. Either all the way up, about half or all the way down. With my flaps on my stick it pretty simple to get what I need even at night.

[BrentHumphreys]

Pretty cool. Is that an Arduino board you are using?

[Brantel]

My question is about failure modes especially with the pot and how the controller will react to the various ways a pot can fail.

If you lose your feedback while idle?

If you lose your feedback while in transit up?

If you lose your feedback while in transit down?

Dirty spot on the pot?

[Rick_A]

Nice engineering job but I changed my mind about the need for an automatic flap control system after flying my -7A.

Prior to flying my RV, I'd flown planes with manual flaps (which I really like) and Cessna's with electric flaps. Some of the Cessna's had the 3 position flap switches which provided the function that you have in your system. A couple of Cessna's that I flew had manual electric switches. There's no doubt that in a Cessna the automatic positioning system is MUCH better then the manual systems and I was convinced I needed an automatic system on my -7.

The -7 is different animal. I was talked out of installing the Automatic Flap Positioning system that Van's sells. It was a good decision NOT to install it.

I marked 10, 20 and Full flaps with tape on the Flaps themselves. It is sooo easy to just hold down the switch for a couple seconds and glance out the window to see how much flap is deployed. It's nothing like the manual electric flaps on a Cessna.

In practice, I find that I normally only use 1/2 flaps for landing. When I'm ready for flaps, I just go straight to 20 deg and leave it there.

[JLuckey]

RatMan -
The mock-up is the quick-and-dirtiest thing I could throw together to simulate a jack-screw mechanism (as you can see, I invested heavily in PVC & particle board) so that I could do the electrical & software development. The direction of deployment can be easily switched (as you suggest).

Also, the number of flap positions is configurable (up to 4 positions). Several people have mentioned that they only use half and full flaps on their RVs, in which case you could control this system w/ a simple 3-position toggle switch.

In addition, although the video doesn't show it, the flap positions are completely user-configurable in the field. (without using a computer) I should probably do another video to demonstrate that feature.



Brent -
Not an Arduino (but Arduinos are pretty cool!)


Brantel -
Always good to look at failure modes and depending on how the position-sensing pot fails the flaps could do anything from just stop moving thru move to the full extent of their travel. (about the same as what might happen if a microswitch fails in a Cessna)



Rick -
It really comes down to pilot preference, doesn't it? Some people see this as pretty cool (seems especially RV-10 people) and some people just don't see the need. As my dad used to say "To each his own", (which is what Experimental aviation is all about


Thanks to all for taking the time to reply..

[Bavafa]

I have gone with FPS plus and have been extremely happy with it. I can set it to any position that I want with as many flap stops as I want, I have three positions currently. It also controls my elevator trim which is very handy in a touch and go or go around situations. I have also installed a manual switch in case of system failure or if I want to control it manually. I have only 125+ hours on the plane but it has worked very nicely so far.

Mehrdad
RV7A- IO360M1B

[loopfuzz]

Nice project Jeff! I agree with you about not liking the idea of having to hold down the flaps switch for each notch.

My flap controller project went a little different route, I just timed the amount the motor took to goto half and full flaps. Your method is more accurate because of the pot to measure the actual distance traveled. Mine method is just a little easier to retro-fit into existing RVs. Cool projects. Fun with Flaps!

Here is a youtube vid of the one I made last year.
http://www.youtube.com/watch?v=H2L0EPofPeI


Chris.

[JLuckey]

Bavafa,

What kind of controls are in the cockpit for the FPS system?



Thanks Chris,

I did mine for exactly the reasons you point out, more accurate position control and actual flap position indication. Also, we have different interfaces w/ selector switch vs momentary on the stick. Different ways to skin the same cat. What kind of microcontroller did you use? Are your flying w/ yours?