General Setting up Flaps

Derek

Derek

Well-Known Member
I have a newly built RCH Trainer and I'm very excited to get it in the air. However, there are some differences that I want on this Trainer that I didn't have on my original Trainer. I want fully functional Flaps. I've seen, on some recent models from Hobby King, the Flaps come down so far that they are nearly perpendicular to the trailing edge of the wing....just like the Multiplex Fun Cub. I'd like to see my new RCH Trainer setup for STOL (Short Take Off and Landing).

I have "Flaperons" setup on my motor glider and they work very well, but I think I have something set wrong because the plane tends to porpoise, but that's for another thread. So, I guess my questions are:

...on the DX8 (with 3 position Flap switch)...

When the Flaps are down, should my elevator be up, down, or neutral?
and is there a special type of "Flaps" control horn that I could use to bring the Flaps down more without over stressing the servo?
 
Lee

Lee

Well-Known Member
There should be some elevator to counter the effect of Flaps. Set up the 3 pos switch with gradually increasing amounts of flaps, starting with very little. See how the plane reacts, then add the elev mix to counter the flaps.
As for the control horn, i don't know, but i wouldn't think so. You could just put the servo end on a hole further away, and the flap end on a closer hole to give for effect.
 
murankar

murankar

Staff member
I would recon that the resolution on the servo would not make much of a difference since you are going to set points, So I would go with what Lee said. Another possible thing is to place the servo close to the flaps, in hopes of getting a 90 degrees of deflection.

As for STOL I think that if you run flaps at or near 90 degrees I think that would create to much drag. I think that if you run near 10% to 20% you may see some success in your take offs. I am basing this on my experience with full size aircraft on a flight sim (Microsoft flight sim 2000, i think it is).
 
wizzard363

wizzard363

New Member
The plane will want to balloon up when flaps are first lowered ,I find mixing about 8% down elevator is a good place to start .
Also on the DX8 you can slow down the flap servo speed , this reduces ballooning and also give a more scale look
 
Derek

Derek

Well-Known Member
Thank you, wizzard, for your comment. Yes, I really like the fact that I can slow the Flap speed on the DX8. Awesome feature!!! However, you are saying that I need down elevator. That's possibly my problem right there. On my motor glider, I have a bit of up elevator. I'll make the adjustment to give down elevator and go fly tomorrow. Thanks!!
 
Derek

Derek

Well-Known Member
When I first set up my motor glider with Flaperons, I was thinking that the elevator needed to be down a bit but the plane would nose-down ALOT. Perhaps I just had too much down elevator programmed in. I changed the setting to give up elevator and in Position 1, the plane would float along pretty well but in Position 2...the plane would begin to porpoise/stall. I'll get the settings changed and I'll try it again tomorrow. I'll be sure to take more than 1 battery because I think it's going to be a lot of "trial and error". Thanks again for your comments, wizzard! I'll report back with my results.
 
Tony

Tony

Staff member
When you dial in flaps, you need UP elevator. NOT DOWN! The flaps are forcing the wing UP BEHIND the CoG, this causes the tail to RAISE. And you have to force that tail down.

I have found that you will need 5-10% elevator to flaps ratio. So if you put in 10% flap, then put in about .5% elevator.

If you dial in down elevator, your plane is going to nose dive.
 
wizzard363

wizzard363

New Member
my 4 models with flaps must work different to yours .
All need some down elevator . You are the first I have heard to recommend up
 
Derek

Derek

Well-Known Member
So I was right to begin with...using UP elevator. Perhaps I just have too much UP elevator and that is causing my motor glider to stall.

Actually, I'm confused once again. My original thought was DOWN elevator but switched to UP elevator. Then, "wizzard" is telling me DOWN elevator and not you are telling me UP elevator. Hmmmmm.....
 
wizzard363

wizzard363

New Member
go with neutral and see what happens . if the model rises when flaps are used then add some down elevator .
I totally disagree with what Tony is saying.
If the wing rises with flap ant you give up elevator then the tail will drop causing a more nose up attitude and will cause the model to rise more

- - - Updated - - -

Add elevator in small doses , only a couple of % at a time
 
Tony

Tony

Staff member
I agree to just leave teh elevator alone and see what it does. I have always had to dial in a little up. But, I hav eonly done this on a couple planes since I fly mostly 3D planes, I don't use flaps much. Who knows, maybe I'm wrong, it happens :biggrin1:
 
corsair_pilot

corsair_pilot

Member
Just curious, how did you go with the flaps?
Seems to be a lot of confusion everywhere.
From what I've seen, it depends on lots of variables as to which way the elevator needs to be deployed. I would have initially said down elevator, so you really have me curious now
 
Derek

Derek

Well-Known Member
No problem! I'm glad you asked!

100%, without a doubt, you need down elevator.

When you deploy the flaps, there is a generous amount of lift being added to the plane, therefore, causing the plane to nose up.....intensely. So, I added down elevator and actually, here is a bit of a story to tell you how I did it.

As always, I had my wife with me (she's so great!!!)...I got my motor glider all plugged in and powered up. I went to the Flap System, on my DX8 and I just entered -30 for my Mid position. It was just a random number that I chose. I had to use the negative number because of the way that my servo's are installed. That "-30" is what gives me down elevator. Then I went over to the "Elev", still in the Flap System menu, and selected Mid option and entered 15. Again, the +15 was just a random number so that I could get the glider into the air and see what happened. Now, I left the Elev selection blinking, so that it could be changed while the glider was still in the air. We get the glider in the air, 60-70 feet up or so and I flip the Flaps switch. The glider slowed down a great deal but also began to nose down. Noticing that, I flipped the Flaps switch back off, throttled up and began to climb again. I asked my wife to scroll the scroll wheel to change the +15 to +10. Drop the throttle and flip the Flaps switch again.....it's a beautiful site!!! Just amazing!!! I can now throttle up to a respectable altitude, drop the throttle, flip the Flaps switch and just let the glider float around for many many minutes. It takes less than a minute to get to a respectable altitude and several minutes to get back down. I'm gonna say it again....it's amazing!!!

Unfortunately, I do have to work this weekend but I will take my motor glider, and video camera, out next week and we'll do some time tests. How long does it take to get to a respectable altitude and then how long it takes to glide down with the Flaps on. Actually, my motor glider has full length ailerons, so my setup is "Flaperons". It's a very cool, preset, function that the DX8 has. I love it!!!

My RCH Trainer had 6" flaps on it and I basically used the same method to setup the flaps on it. It was a real treat to fly. The flaps also aided in the take offs, too. It was just a lot of fun!!!
 
corsair_pilot

corsair_pilot

Member
Awesome!!
From other reading I've done, some do need to have up elevator, but lots of it based on where the COG is, as well as wing position.
Having a bit of down makes sense to me, the whole idea of them is to slow the plane down, and still get lift at slower speeds. So in my head, the idea of a bit of down elevator makes sense.
Anyway so glad you got them to work properly!!
Look forward to the videos!!
 
Derek

Derek

Well-Known Member
I actually did try Up elevator, at first, because that is where my mind was taking me. I quickly realized that this was not going to work because, on my motor glider, after flipping the flaps switch...along with up elevator, my motor glider would nose up very hard, then stall and I was then left with a plane that would porpoise through the air. It was awful. So, after talking with Tony and a few other members, I changed the settings to down elevator (just as I described above) and I just love the way it flies now. I'll be sure to get video of my motor glider next week. Hopefully the weather will still cooperate.

Take care buddy!!!
 
Derek

Derek

Well-Known Member
Hey Jonathan....I finally was able to get out and do some flying. I took my motor glider out, and some other planes, and I did take the video camera and I show a bit about how the flaps work with down elevator.

I'll upload that video tonight. It's time to eat right now, lol.
 
You must log in or register to reply here.
Top Bottom