bob27s

My Feedback: (19)

I agree....

that was the standard timing for the roll sequence....

If you want a higher rate for half-rolls on stalls and Cuban-8, no problem there. Set the high rated to what ever feels comfortable. Set the low rate to match the 3x5 roll sequence.

Years ago I never touched the roll dual rate. Used the same rate for everything.

Also, if you have not sealed the control surface gaps, especially on the ailerons ........ do so before adjusting the control throws. Just doing that will nearly double your roll rate and will make the rolls smoother and more consistant.

Bob

WEDJ

Back then, I used high rate for 3 x 5 sec rolls, and low rate (2+ sec rolls) only for the slow roll maneuver. Elevator high rate for spin, snaps and landing, low rate for everything else. Rudder rate was slaved to throttle position.

dszabo2

My Feedback: (1)

Had a chance to fly again this week end with the rates on my radio increased to 140% through the radio. My original estimations of the roll rate were off by quite a bit. With the increased travel I timed the roll at just over 2 second. When I put it back to 100% I was at a 3 second rate that would be nine second for three rolls. Both measured at close to full speed.

Sorry for the wrong original post on the rate.

Im using futaba 3004 servos, 4.8 volts and the ailerons are sealed over the entire length on the bottom side of the wing.

Any thoughts on what could be wrong????

Dave

Free Bird

Where is the pushrod connected on the servo arm and the aileron control horn? Further in on the servo arm = less throw. Further out on the control horn = less throw.

FB

dszabo2

My Feedback: (1)

My original deflections were set to 1/4" on low rate and 3/8" on high high rate. The 140% setting probably increased the throw to about 1/2 inch

I do have it set up with differential throws, therfore the down throw is less than the up throw This is done mechanically by use of a round servo arm

Dave

patternwannabee

My Feedback: (1)

Hi Dave,

Sorry, I've been out of town last week.

Did you go with the "classic" single servo in the center of the wing installation or one servo per wing half?

If classic, how is the aileron movement (moves freely?), and can the servo withstand some resistance? Actually, I figure you know this since you fly 3d, but I thought I'd ask anyway.

Assuming you have unimpeded aileron servo movement (strong and fast), then it's probably an aerodynamic concern. Perhaps you could pose the question in the aerodynamic forum.

I installed my servos 1 per wing panel and on its side. I was never wanting for aileron throw or roll speed.

3 sec/roll is pretty darn slow. You could try increasing throw little by little using a bigger servo wheel until you achieve the roll rates you desire.

Good luck.

dszabo2

My Feedback: (1)

patternwannbee

I do have it set up with the classic single servo in the center and as I mentioned, it is set up with mechanical differential thows. The surfaces do move free and response seems OK, but thats in a static mode. I now question if a futaba 3004 servo on 4.8 volt will have enough torque. The plane is a little over weight coming in at 7.5 lbs, its supposed to weight 6.0 lbs (too much clear coat LOL)

I did change to a longer servo arm but did not fly it this past weekend. I do have a higher torque digital servo and I think I will switch it in to try out this weekend.

Dave

UStik

If all else fails, you could put strips of adhesive tape (masking tape or Scotch tape) on the sheeted parts of the wing in front of the ailerons (and if that fails even on the sheeting in front of the covering) - trip strips.

It's just a shot in the dark, but it's so easy to take some tape along to the field and apply it to the wing (which looks very smooth). At least it's easier than checking the airfoil shape and leading edge radius over the whole span.

I personally would do the reverse of what you did, I'd set no aileron differential in the first place. If you set up substantial differential you'll get yaw and lose roll rate, and the huge deflections are like slamming on the brakes, making things worse.

bob27s

My Feedback: (19)

if you can post a few photos that would be helpful.

With the throws you identified, the plan should fly well with a reasonable roll rate.

Something else is amiss...

dszabo2

My Feedback: (1)

Tomorrow I will post some pictures showing the aileron / servo set up.

UStik

... and a close-up of the overall wing shape, please! It's so interesting!

If the ailerons merely stir in the wake of a separation bubble, any discussion of servo, linkage, throw, and differential would be pointless.

(Not to offend you, I just like to muse about such things and love to know for sure if I'm right or wrong.[8D])

dszabo2

My Feedback: (1)

Here are pictures of my original set up.

UStik

Thanks a lot, that's a very nice airplane! I don't see any odd things, just not sure about the leading edge radius, and really seems to be very smooth wing surface (and a thick wing). Sorry, no idea other than the shot in the dark (the tape).

patternwannabee

My Feedback: (1)

Hi Dave,

I can't help but think that there's some resistance in your aileron servo setup.

I'm reminded why I'll no longer use the center aileron servo setup. So much that needs to be adjusted and so much that can go wrong.

It looks like the right aileron ball is canted pretty far forward. Seems to me that when the servo pulls on this link, the ball link might bottom out causing resistance?

Also, maybe it's the angle of the picture, but it seems the Left aileron pushrod is significantly longer than the right?

I'm assuming the additional bends in the control horn are to avoid hitting something in the servo compartment?

If indeed the aileron travel is smooth and unimpeded, then I agree with Bob27s...something else (aerodynamically) is amiss.

BTW, the ball link on the aileron horn is probably not the most secure type of link. Should it come loose, then you've got real sloppy ailerons that could lock in an unusual position.

dszabo2

My Feedback: (1)

I dont care for the the ball link set up either. I was forced to use it because of the bend I needed to put in the push rod to clear the fuselage. I have it quite secure.

There is no slop in the ailerons, so I dont think going to dual servos will buy me anything. I also put a digital servo in for inreased torque. If that doesnt help I'll do away with the differential throw. To UStik's point, increasing throws will be like putting on the brakes.

Dave

WEDJ

Considering you're complaint of not enough aileron authority, first thing I'd do is go out a hole in the servo. (bigger servo wheel)

PS - the photo is worth a 1,000 words.

NM2K

My Feedback: (14)

One of the first things that I do when building a classic pattern model, is to increase the chord of the ailerons (front to back dimension). Why folks used such ridiculously small control surfaces is probably a hold-on to the days before proportional (reeds) when you had all or nothing. In order to fly smoothly with all or nothing, you reduced the size of the control surfaces. Unfortunately, this habit persisted for quite a while even when proportional systems were quite common.

Problem is, when you increase the surface area of a control surface that is controlled by a torque rod, flexing of the torque rod becomes readily apparent, giving the controls a mushy, unpredictable, response. Hence, the need for going to separate servos in each wing panel and eliminating the mushy torque rods. All torque rods flex, unless they are large diameter tubing.

Ed Cregger

dszabo2

My Feedback: (1)

Ed

I agree that a torque rod will flex more than independant servos with a direct link. However, I have my plane set up per the plans (designed by Art Schroeder - 1972) which call for a single servo and torque rods. I would imagine that many eyeballs have the same set up and get the expected roll rate.

I must be missing something??

Dave

NM2K

My Feedback: (14)

Ah, but in those days, pilots were not accustomed to flying models with tight, direct control surfaces as we are today. Going back to an old design after decades of flying much better models will reveal the shortcomings of the old single servo/wire torque rod systems. What may have been a wonderfully set up model for the olden days would be viewed as a wallowing cow today.

Ed Cregger

UStik

Hi Dave, did you give up on the plane? I would like to hear how it turned out, especially if you tried trip strips. I found/borrowed a picture showing that/how it's done full-scale, hence this bump.

dszabo2

My Feedback: (1)

UStik

No I havent given up. I am just slow to make the changes since I've been flying my other planes. I did increase the throws and take out the differential and I am now about 2.5 seconds. I will still increase the throws some more.

Thanks for the picture. I cant see how a thin strip of tape will increase the effectiveness of the airlerons?

Dave

UStik

Dave, I learned that from the glider guys (and needed trip strips on my glider to help sluggish ailerons). The only illustration I found quickly is [link=http://www.mh-aerotools.de/airfoils/bubbles.htm]this one[/link]. Obviously these bubbles are common on models and their wake may go beyond the trailing edge. The Eyeball's narrow ailerons may be affected by this wake. The trip strips avoid a bubble and let the air flow closely around the ailerons.

2.5 sec is not bad but you should have it with far less deflection. Again, applying a strip of tape is an extremely easy experiment and you can't lose. The boundary layer is rather thin, so for gliders, trip strips are a trade-off (aileron effectiveness - performance). But you may use rather thick tape and the Eyeball won't even notice it. Maybe you'd need two strips like the two rows of turbulators in the picture above.

dszabo2

My Feedback: (1)

Ustik,

You may be on to something here. I did a guick google on trip strips and had many hits related to tubine blades. I started to read up on it, but its been a long time since engineering school and it will take me a while comprehend it.

In the mean time I will try your idea of the tape. Unfortunately our field is close this week end and I am on vacation the week after. So it will be a couple of weeks before I can test it out.

I will keep you posted


Dave
Dave

Walt Thyng

My Feedback: (9)

How cool to find this forum and so many threads on the Eyeball. My fist high performance plane as a member of the Kennebec Valley Flyers in Sibley, Maine was an ARF Eyeball. for years I remembered it as a Lanier, but was told that they never offered it. Some suggested it was a D&J or J&J kit. All I remember was that it had a red ABS fuselage and white foam core wings. I flew it with a Kraft 4C and a Supertigre bluehead 60 until it literally fell apart on landing.

I recently acquired a MkV version from Eureka A/C and plan to build it this (too rapidly approaching) fall. My original was trike gear, but I'm going either with retracts or bicycle gear. In an act of utter blasphemy I'm using e-power as that's all I've flown since 92.
Walt

dszabo2

My Feedback: (1)

Walt

J&J industries made the Mark V as a kit, which is the one that I currently have. Coincidentally I passed by the box it came in last night and saw the price tag marked at $24.99.

You are right it would be blasphamy to convert to electric however I would like to see a picture when you have it finished

Dave