If it is not balanced on the same axis as the aileron, it's relationship to gravitational pull does for a fact effect the balancing force, as evidenced by my test. Try it yourself. It's mass balanced, but not with respect to gravitational force.

Propellers are a different animal. It's not a apples to apples comparison.

I'm not suggesting that "balances" are not effective. Only that when configured as discussed, it is not truely balanced at any other angle other than horizontal if only one balance is used. And furthermore, if only one balance is used, some of the balancing effect is lost due to wind resistance pushing the balance (and aileron) in the opposite direction of the balancing force. It will still serve as a oscillation dampener, but it will not be truely "balanced".

Was the CAP flown with one servo, and no balance used?

Time will tell when (if) someone tries a DP Extra with only balances used. But it won't be me trying it. I believe one gentleman reported loosing his DP Extra ailerons due to flutter, and landing without damage, and then correcting the problem with dual servos (and maybe some strengthening of the ailerons). DP also recommends this solution, and may be providing a dual servo configuration in the newest version of the kits. Sounds like the only tried and proven solution so far with [B]this aircraft[/B[. I'm not willing to risk my $1500 investment to an unproven couple of fishing sinkers hastily scabed onto the ailerons.

And my personal CG does change when I bend over because of a transmitter holder I have protruding from my abdominal region

Ben;

Internal counter weights would indeed be impossible with the huge amount of control throw we are dealing with. Something else that is different than full size aircraft which utilize counter balances.

How is this problem handled on a full size stunt airplane like an Extra?

I seen something strange but very nice the other day. A gentlemen was flying his Dave Patrick Extra ARF without any major mods to the ailerons. He had one Hitec 5625 digital servo per wing with 4-40 rods the sullivan hardware. He had a big Fuji 50 gasoline engine mounted on the nose! I was amazed as it lifted to the vertical right on takeoff! Lots of power, no flutter and was a pure delight, after all my agonizing. He had a number of flights already with this set up, and so far so good. He had that thing doing full throttle passes and putting it through its paces. I was especially interested, as Im putting a Zenoah G45 in mine. That Fuji 50 was turning a 22X8 or 10 prop (I know it was 22") around 6800 rpms. Wow! I hope my g45 will be as good! We will see. So guys, there is a light at the end of this tunnel, just hang in there! He did have problems with his main gear bending, and has since beefed up. Im opting for the TNT T-6 aluminum gear and Im hoping for the best!

By the way, this is the second of the Dave Patricks that I have seen fly. The other one had a OS 1.6 in it, and no flutter problems. so........?????

I've seen other high powered electric "E3D's" like I am having trouble with, fly with no aileron flutter, and no fear of "going over the speed limit". Problem is that mine flutters if you "pass wind" in it's direction. When a design pushes the engineering envelope, disasters are prone to occur in conjunction with manufacturing and material variations.

The potential obviously exists, as evidenced by reports on here, and the fact that DP has specified a "fix", as well as a reported dual servo configuration on the next run of kits. My DP Extra was supplied with a suppliment about using dual aileron servos.

It would be nice if DP would/could chip in here and tell us what he knows. Like identifying any possible runs or kit modifications that did or did not have problems. But I don't think I would stick my own neck out that far.

Milage no doubt varies. I've run out once or twice, and I prefer to fill up before the needle gets in the red

Does anyone have pictures of the counterweights used on the full scale Extra ailerons? It is a proven feature used on full scale planes. Please note in my earlier thread about balance vrs. gravity, I used the the term "truly" balanced in case I've have ruffled any feathers. The weight method experiment above does promote a bias at different angles when static because is not truly balanced (over hang at an angle), and because the airplane is not pulling G's perpendicular to the airfoil. Gravity in a static test is toward the ground. Also not discussed yet is the range of the counterweight's effectiveness. It's only needed near neutral deflection. Flutter usually wouldn't happen with aileron deflection unless the torsional type is the problem, but that's the easy one to fix. I was actually hoping I would need some aileron trim on this plane to get some bias away from neutral (first plane that didn't need it). As far as the CAP story above..... Bill Pryor, could you fly your 33% CAP for us with one servo, no counterweights and give us a report? Please, purdy please?
Move over Butter!

Hey KatMan-

Dew the aileron balance perfectly when the wing c/l is level? It appears to me from looking at the picture that the counter-weight is too heavy for that aileron. Seems to me that it should be like a propellor when both blades are perfectly matched in weight; it should balance at any rotational position in which it is placed. Also; is it not best for the weight to be centered (as if placed on a "tip plate" extension) with respect to the c/l of the wing and aileron? Not that it necessarily has to be, but just works better that way? The aileron shoud not displace from neutral in any position the wing is placed. That is what makes them work. That is my understanding of balanced ailerons. Any experts care to comment? It appears that we have finally reached the point at which we are headed in the right direction with this thread. Kinda' sad.....I've learned a lot :-))

Regards to all; C.E.

Shed Spread

There is no relationship between the location of counterweight used for mass balancing flight control surfaces and the ground. Does the CG of your airplane change during vertical maneuvers? Why would the CG of a control surface change?

In a perfect world, the hinge line would be recessed in a rounded leading edge and the counterweight could be placed in the leading edge, forward of the hinge line. Since we can't do that here, we attach it externally. This is sometimes done in full scale too with the addition of spades. In addition to adding mass forward of the hinge line, spades provide an aerodynamic balance to the control surface as well. This results in less force required to move the surface.

Scroll down this page and read "Aileron spades".

http://www.airandspacemagazine.com/a...2/AM/fusd.html

-Ben

Thanks Ben, good reading! Here's a picture of some counterweight nose ribs in the construction of a full scale plane aileron. I beefed my DP ailerons with lots of extra glue at the leading edge to accomplish what you see here.

I am currently flying a H9 330L 1/3 scale Extra with a ZDZ 80.
The ailerons are counterbalanced with a 2oz lead wt on a rod 4" ahead of the hinge point at the tip. The wt is outside of the tip that in this case is not rounded. The aileron is controlled by one Futaba 9250 digital servo on each wing.
On about the 17th flight, while assembling the airplane it fell off the table and broke the plastic gear in one of the servos. I remember checking the controls and it seemed to be ok. However in the flight it didn't seem to respond like it should so I landed. i found the servo was completely loose with the aileron free to move as it wished. There was no flutter.
I called Futaba and asked if they would send me some new plastic gears because I didn't want to pay $54 for a gear set for this servo that contained the metal gears.
They sent the gears by UPS air as I was going to an IMAA meet on Sat. Unfortunately this was Monday Sept 10'th.
At the meet, since since I had no gears, I tried to replace the gear with one I got out of an old servo. It seemed to fit. I put the servo in and tested it by moving the control back and forth for ten minutes.
I took the airplane off. After about 1 minute I again noticed a loss of sensitivity in the aileron control. I landed and found the servo had broken the gear. Again there was no evidence of flutter.
After I received and installed the new gears, I have flown the aircraft about 25 times without incident.
To me this proves the effectiveness of the lead wt.

Let's think about this for a minute guys. Take two equal size and weight pieces of anything, say wood for simplicity. Bevel the edges of the pieces at a 45 degree angle and glue them to together. Now tie strings at the outside of the corner where the pieces are joined, and suspend the attached pieces of wood from the strings. At what attitude do you suppose the pieces of wood will hang from the strings?

Something like this, maybe?

Kat- Try thinking in terms of mass and inertia instead of gravity. The inertia of the surface oscillating in the airstream causes flutter. By damping with counterweight, the momentum is reduced.

-Ben

I understand that just fine. It's a oscillation dampener, as I mentioned previously. It has been referred to as a "balance", but it cannot act as a "balance" at all attitudes if it is configured off axis.

The counterweight is acting to "balance" the mass, not the weight.

-Ben

DirtyBird,

Thanks mucho for the informative example.

When an aileron or wing is displaced, it is the unbalanced condition of the aileron which causes it to "lag" the other surface, thereby reinforcing the other surface's travel in its original direction. The originating surface then travels to its mechanical (for the moment) limit, "dragging" the secondary along, but leading it by XX degrees. Positive feedback loop. Balanced ailerons do not lag............

Kat: in your example, If I am picturing your example correctly, the two pieces of whatever if suspended at the ends of the "hinged" or "glued" axis would remain exactly where you left them.

Diss: You're Right on..........

Regards, C.E.

Kat,

RE: your picture; double-bevel the inside edges (as in a wing/aileron) with both sides being equal in weight, suspend the assembly from two points at the ends of the bevels, that's what balanced ailerons are. (Your picture had not come up when I first saw your post :-)

C.E.

OK guys. I just got a beautiful DP Extra for my birthday today, and when I look for a little info I find this thread! Geez! What luck! Wish I had seen it before this morning!

I have two questions about this plane.
1. Has there been any failures with the dual aileron servos?
2. Is the OS 160 really enough to fly this thing? I wanted to go gas, but now I'm afraid to risk the extra expense!

This is an absolutely beautiful plane and I want to keep it that way! I just lost a plane due to flutter a few weeks ago, and do not intend to have to go through that again! I intend to use it for 3D. Help!

Razorback,

There are many times more r/c'ers flying the DP330L and having nothing but success than there are who are being successful at having nothing........ I'm not throwing stones; just putting the situation in perspective. There seems to be some validity to some of the kits coming with very flexible ailerons that are subject to flexing or twisting laterally.

There is some anecdotal evidence of this phenomenon (flutter) happening at very low airspeeds. I cannot personally vouch for these, and one man's "slow" is not necessarily another's. Most of the methods mentioned in this string are symptomatic in their approach. They all dampen what has already taken place, but do nothing to stop it's onset. To illustrate this, go to any site dealing with aerodynamics and do some research.

There are literally hundreds of good solid suggestions re: R/C advice on R/C Universe, and some well-intentioned advice also. Don't let it alarm you unnecessarily. There are conditions which may lead to flutter. Some are: Exceeding V-sub-ne (over-speed, that's why wings come off full-scale when they go faster than design maximum); Loose linkages; unsealed gaps between fixed and movable surfaces; Movable control surfaces having "mechanical advantage" over the servos driving them (Important!!), and what I consider to be the most important: unbalanced ailerons. (there seems to be some misunderstanding on this thread of what "balanced" control surfaces consist of). Most, if not all, full-scale aircraft utilize balanced ailerons, but it still gets the best of 'em! The larger our "miniature aircraft" the more like their big brothers they behave. That F-117 Stealth fighter that crashed at an air show back east several years ago was a victim of flutter. If you look at the tape of the crash and pay close attention to the left aileron/wingtip, you'll see a prime example of flutter! I believe they blamed that one on maintenance. My main point is this: do some research and don't take anything for gospel without it. (Including all of this :-) Satisfy your own curiosity. I have gotten some very good information and advice on RCU, and it's an invaluable source of information.

Just be aware of the difference between anecdotal and empirical evidence. Most of all: Have Fun. The DP330L is a great airplane. The DPM 60" Ultimate is.......well, read the review in RCM.

Excellent advice C Ernest! You're dead on. There is some great information and advice on these forums, but it all needs to be taken in perspective and weighed carefully to judge how to act on it.

BPryor,

Thanx, :-)

CE

Take it from me, use dual servos if you are going to use a gas engine. As posted earlier, I lost both ailerons at mid-speed. I haven't had one bit of flutter since installing the second aileron servos. I use a Moki 2.10 and it doesn't have adequate hovering power, ie, the "pullout punch," but it does have unlimited vertical. I live in K.C., whatever elevation that is. I don't know what your flying style/preference/location/elevation is, so it's hard to say if the 160 is enough for you. I am planning on eventually installing a ZDZ 50 or something similar, but it's a back-burner thing at this time. The 2.10 provides about 85% of the power I wish it had for this plane and my flying style. It will 3-D great with the right engine and prop, regardless what some websites say. I've seen the DP Extra with an O.S. 160 and it was fairly peppy, but not the extreme 3D that I like. You simply cannot fly this one in full throttle down lines or it might flutter apart.

It is hard to sort through all of the opinions because of so many different thoughts on what is enough and not enough. The most disappointing thing for me is to install an engine on ones advise, then it not be enough. FYI, with two servos in the tail, and the Moki, I still had to add 2 1/2 oz. of weight to the tail for my liking.

JW

I disagree, have you seen www.3dbatix.com?

download the video, this guys using a moki 2.1 and his vertical is awsome

JW-

What IMAC style plane can you fly full throttle downlines with, that won't explode?

-Ben

Hi Shortman,

I had watched the video before, but I watched it again with the vertical performance in mind, and what's hard to judge is how much throttle he's using, but if he's using full throttle out of his several torque rolls, it only appears to be barely adequate power. Also, in the opening sequence, when he goes vertical, it appears to run out of steam....but of course, again, you can't judge how much throttle he is using, so my take is that's the jury is still out based on that video, but if he was using full throttle, then RCU is right about the vertical. We don't know the weight on that plane either, which will make a big difference on the performance.

My DP Extra with a Taurus 2.6(lightened to 15lbs) would pull out from a hover at about the same speed as the plane in the video........at about half throttle. It hovered at 1/3 or less throttle. It would rocket out at full throttle. That was with a Zinger Pro 22X8 turning 7200 RPM.

I have seen the video also, and have spoken with the videp pilots' dad....Dad said son recently participated in a SCAT contest where son felt that power on the uplines was not sufficient. Apparently son was doing a 4-pt roll on an upline (or something similar) and didn't quite have the punch son desired for completion of the maneuver.

That being said, this kid can 3D...He is awesome...