What is appropriate maximum control deflection?

[Phil Krankowski]

I am finishing the control setup on a Flite Streak built to the plans, and a Flite streak with a stretched fuselage and over sized horizontal stabilizer.

What do YOU have for maximum control deflection, preferably in degrees, for non-flapped ships in the size of a Flite Streak or Sky Ray 35?

Thank you

Phil

[steve bittner]

30 degree has my vote, good answer Ty

[Randy Powell]

Interestingly, some of use have been experimenting with more control throw (for electric planes). Howard Rush had a camera mounted on planes pointing to the control surfaces. I was a bit surprised by how much we use. I often build planes with no more than 20 degrees available and it seems that's not enough.

[Paul Walker]

Interestingly, some of use have been experimenting with more control throw (for electric planes). Howard Rush had a camera mounted on planes pointing to the control surfaces. I was a bit surprised by how much we use. I often build planes with no more than 20 degrees available and it seems that's not enough.

Well, that camera was on my plane and it showed that it just got to 20 degrees on the hardest corner I could do. That was flap deflection that was measured.  Maybe on a non linear system it might go more. Need to put that camera on one of my non linear planes to see how far it is moving.

I have a new flite streak and 30 degrees is about where it is and it is OK. Depends on where your CG is going to be.

[Tim Wescott]

I suspect this is misleading as all get out -- but here's the elevator deflection of Test Pig #3 as she was flying the eights (first round, then square).  If I got my calibration right, that's a deflection of nearly 40 degrees in the square maneuvers.

I'm not sure how much I trust these numbers, though -- both my Skyray and my Flight Streak were set up to max out at about +/- 40 degrees, and they had less elevator than Test Pig #3.

[Randy Powell]

Paul, I was looking at the video on Mark Scarborough's plane. Seemed like more than 20 degrees to me (maybe 30 degrees). I usually set my planes up for 20-25 degrees but have been rethinking that.

[Phil Krankowski]

Hmm...

Right now I have 20 degrees on the tallest setting on the control horn on the one I have the elevator on.  Sounds like I am in pretty good shape, as moving down gives more movement.

Phil

[Tim Wescott]

There are so many variables that there's no one good recommendation.  You can say things about a "typical flapped stunter", or Skyrays specifically, or Flight Streaks specifically -- but not about everything.

As long as the elevator itself will travel +/- 40 degrees I think you'll be set -- you can try the thing out with it set up for less motion, then if you're just not getting enough turn you can move the pushrod up on the control horn.

I do suggest that you make sure that with the pushrod closer to the elevator you still have full range of travel.

[Randy Cuberly]

I think another player in s equations is how large and effective the flaps are.  They do, of course, give an opposing control force to the aircraft.

I know this is nothing new to most of us but maybe some newbies haven't thought of this fact yet!

Randy Cuberly

[Phil Krankowski]

Flaps are fixed in this case.  I currently do not possess a flapped airplane, and do not expect to have one soon. 

I get non-binding travel for over 45 degrees in both directions with the pushrod disconnected.  I have a screw end on the pushrod with a clevis so I can adjust as needed.  I have about 3/8 inch adjustment on the clevis in both directions after adjusting it on the tallest position.

Everybody around here fly RC.  I get interesting answers about adjusting travel in the radio...

Phil

[Mark Scarborough]

Paul, I was looking at the video on Mark Scarborough's plane. Seemed like more than 20 degrees to me (maybe 30 degrees). I usually set my planes up for 20-25 degrees but have been rethinking that.

hmm randy,, I dont think I can deflect my controls in the profile to 30 degrees,, I wonder if there is some optical delusion going on here 

[Phil Krankowski]

I picked up one of these today.  For the price it is pretty nice.  Yes, this is the exact reason I got it.
http://www.harborfreight.com/multipurpose-angle-finder-1028.html

Phil

[Tim Wescott]

Everybody around here fly RC.  I get interesting answers about adjusting travel in the radio...

What, your handle doesn't have buttons and an LCD screen, with a jog wheel so that you can select the right program for the right aircraft?

[Phil Krankowski]

What, your handle doesn't have buttons and an LCD screen, with a jog wheel so that you can select the right program for the right aircraft?

Nope!  Not this one at least!

Phil

[jim gilmore]

wonder how the number of degrees of travel compare to the actual size of the flaps and elevators..
Add just 1/4 inch to the back of the flap and the number of degree of travel might need to be less

[Howard Rush]

wonder how the number of degrees of travel compare to the actual size of the flaps and elevators..
Add just 1/4 inch to the back of the flap and the number of degree of travel might need to be less

I think that's true, but then strange things happen.  Hinge moment goes up approximately proportional to flap deflection, but approximately proportional to the square of flap chord. Adding flap chord thus causes hinge moment to increase for a given amount of wing lift.  Adding flap chord thus results in a greater difference in tension between the two control lines for a given amount of wing lift, which makes the airplane harder to fly accurately.  Hence Ted's advice, which I think I finally figured out, not to use any more flap chord than necessary. 

[Steve Fitton]

I think that's true, but then strange things happen.  Hinge moment goes up approximately proportional to flap deflection, but approximately proportional to the square of flap chord. Adding flap chord thus causes hinge moment to increase for a given amount of wing lift.  Adding flap chord thus results in a greater difference in tension between the two control lines for a given amount of wing lift, which makes the airplane harder to fly accurately.  Hence Ted's advice, which I think I finally figured out, not to use any more flap chord than necessary. 

I just learned something.....  woohoo!

[EddyR]

Most already know this but some may not. I like many others when building Ringmasters back in the 1950-60's that always had almost straight up and down on the elevator.We thought more than 45 degrees was needed . About 15 years ago I built a light Ringmaster and had only set it up with 15 degree movement. It would do a hourglass and anything I asked of it. It weighted 27 ounces with a ST/35 on it. It was fun to fly.
 For many years back then we built a lot of travel in the elevator in case we needed in. Are thinking was incorrect as the large deflection made maters worse. If you wish to do the Sabor Dance then a lot of travel is needed to stall the plane like a BySlob.
Eddie

[Tim Wescott]

I think that's true, but then strange things happen.  Hinge moment goes up approximately proportional to flap deflection, but approximately proportional to the square of flap chord. Adding flap chord thus causes hinge moment to increase for a given amount of wing lift.  Adding flap chord thus results in a greater difference in tension between the two control lines for a given amount of wing lift, which makes the airplane harder to fly accurately.  Hence Ted's advice, which I think I finally figured out, not to use any more flap chord than necessary. 

You just had to put it into math.

I watched a practice flight recently where my flying buddy had a slow engine run, flaps in need of tweaking, and consequent line tension issues.  You could see that in the outside overhead maneuvers the plane was basically just hanging off of the "down" line, with the "up" line completely slack, with a good foot more sag than the "down" line.

[Mike Haverly]

Tim, do some judging.  You'll see a lot of that.

[Chris_Rud]

This is a test for VG's but you can at least see the flap and elevator deflection.



-Chris

[Keith Renecle]

Hi Chris, thanks for posting the video. It's really interesting. What conclusions did you come to........did the VG's make any real difference?

Keith R

[Ted Fancher]

... Depends on where your CG is going to be.

That's the right answer!

Ted

[Ted Fancher]

Paul, I was looking at the video on Mark Scarborough's plane. Seemed like more than 20 degrees to me (maybe 30 degrees). I usually set my planes up for 20-25 degrees but have been rethinking that.

With all due respect, Randy, the only correct answer is that you should have more available than you think you'll need.  That's why God (or maybe Bob Baron) designed the adjustable control handle.

It's the old saw that goes something like this... "You can always use less than is available but it's really tough to get more if you need it!"  I may have just made that up.

Ted

[Ted Fancher]

Adding flap chord thus results in a greater difference in tension between the two control lines for a given amount of wing lift, which makes the airplane harder to fly accurately.  Hence Ted's advice, which I think I finally figured out, not to use any more flap chord than necessary. 

Praise the Lord!  I finally scored one!

Ted "no more chord than necessary" Fancher