Question about electric flaps

Papa · #1 12-01-2008, 06:35 PM

Well, the airplane (RV-8) is finished and out at the hanger waiting for its inspection on Thursday. So far, so good. I do have a question about everyones experience with the electric flaps, however. My flaps operate as they should, but the motor really seems to labor, especially when the flaps are retracted. Out of curiosity, I disconnected the motor from the weldment, and moved the flaps by hand. I did this using the same weldment that the flap motor normally attaches to. It didn't seem to me that there was an excessive amount of resistance, just what one might expect given the size of the flaps and the length of hinge involved. When I've been actuating the flaps electrically, it's been with just battery power, but the battery is recently charged and turns over the engine without problem. What are others experiences with this? Any insight would be greatly appreciated.

Mark

tinman · #2 12-02-2008, 04:11 AM

Mark,
On the ground, the upstroke will put a strain on the drive. In the air, the downstroke will strain the drive.

Shockwave · #3 12-02-2008, 07:44 PM

We noticed the same thing on a 9 when we put the side covers on. We grabbed the flap bracket and we couldn't stop it by hand so it definitely wasn't stalling or lacking power. Best we could figure out was just the sound changed that much with the upholstery and covers. This happened to us with the wings off, I don't recall the noise changing again with the wings on and flaps hooked up.

Papa · #4 12-03-2008, 08:34 AM

Thanks guys,

It's probably not an issue, so I guess I'll just keep an eye on it and make sure it works as advertised in operation.

Mark

Brantel · #5 12-03-2008, 08:43 AM

These linear actuators can take a huge load without stalling with a fully charged battery. Matter of fact, they can and will bend airplane parts if you jam them up on something.

I would say that if you can move the flaps by hand with the motor disconnected and there is no excessive binding or drag, that your fine. It will loosen up over time anyway.

sglynn · #6 12-23-2009, 11:23 PM

I installed my flaps and cut the fuselage hole today on my 7a. My flap motor is new but seems really weak. It could barely pull up or push down the flaps. It labored a lot. I had to assist by pulling up and pushing down on the flaps. It could barely turn at the top and bottom when the clutch releases. I can move the flap weldmount by hand just fine. My battery is reading 11.4 volts. It is really very slow at moving the flaps. I 've read the threads in here about grease cleaning and buying a new motor. My first impression is that the motor is way under powered. Or maybe I need to relieve friction somewhere. Or maybe 11.4 volts just won't do it.

Any suggestions?

molson309 · #7 12-24-2009, 12:01 AM

The motor on my 7A is powerful enough to bend parts if it gets jammed. If you're not seeing much torque out of yours something is definitely wrong.

Frank Smidler · #8 12-24-2009, 08:36 AM

Check to make sure nothing is keeping the actuator from properly pivoting.

When I wired up my flap motor for the final time and checked it out, it worked great, up and down. Then I installed the side covers (RV-6). The next day, being proud of my recent accomplishment, I decided to cycle the flaps again. It was obviously slow and labored compared to the previous day. What I found out is that one of my screws attaching the side covers was long enough to contact the base aluminum block of the actuator. The screw kept the actuator from pivoting causing binding. I cut the screw down and it has worked fine since. On the side cover, next to the one short screw, I have a decal stating max screw length at that location.

Bob Axsom · #9 12-24-2009, 09:37 AM

Batteries do not have the same power through the full range of "usable" voltages. Just turning the motor with no physical load can be a struggle. If the charge is low the open circuit voltage may look acceptable but under load the internal resistance of the battery may have most of the circuit voltage drop across it instead of the external resistance. This kind of testing in the shop as you make the initial installation is not real meaningful except to verify that the direction of travel is correct with relation to the switch position. I used a fully charged external battery for my functional test. You should wait for your performance testing until the airplane is operational I believe. In five years of flying the electric flap function has been flawless on our RV-6A.

Bob Axsom

gasman · #10 12-24-2009, 10:02 AM

Quote:

Originally Posted by sglynn

I installed my flaps and cut the fuselage hole today on my 7a. My flap motor is new but seems really weak. It could barely pull up or push down the flaps. It labored a lot. I had to assist by pulling up and pushing down on the flaps. It could barely turn at the top and bottom when the clutch releases. I can move the flap weldmount by hand just fine. My battery is reading 11.4 volts. It is really very slow at moving the flaps. I 've read the threads in here about grease cleaning and buying a new motor. My first impression is that the motor is way under powered. Or maybe I need to relieve friction somewhere. Or maybe 11.4 volts just won't do it.

Any suggestions?

A full 14 volts (20% more than what you are using) will give the motor it's full torque.............