Dave Patrick 330L Aileron Flutter
 

Davros

It's always a sad day when you loose a model, let alone on the maiden flight, my condolences...

Would you share the specific's of the aileron linkage setup, please? Servo arm length, control arm length and type. Control arm overall length from hinge center line to clevis pivot point?

My model is setup for maximum surface deflection bevel to bevel on all surfaces.

I have one of the first release models of this ARF. Many flights with a Taurus 2.6 @ 15-1/2lbs. I have never had a flutter issue with my model. I replaced all the hardware, Rocket City control horns, 4-40 Titanium push-rods, Digital servos with MG's.

This model flies exceptionally well for the size and wing loading. It's highly capable of all 3D aerobatics. I am very pleased with mine.

I have used props from 20/8 Mejzliks through 22/8 Menz S's.

Dave Patrick 330L Aileron Flutter
 

Its not just gassers...as posted previously my friend flew his with an os 1.60 and it fell apart on take off... :confused:

He called DP and got a replacement at 1/2 cost. Better than nothing I suppose. But 2 servos were damaged and the motor was cracked...

Seems like a relatively "common" occurence.

Dave Patrick 330L Aileron Flutter
 

Jeez, guys,

Spend a few bucks (you MUST have a few bucks or you wouldn't be buying stuff like the DPM300L) on upgraded hd'ware and throw the kit stuff in your spares box for smaller planes, or donate it to your club for the "newbies" to use.

"There is a Dragon that lives out there, near the speed of sound, and he'll get you............" We all know a little (or some, a lot) about flutter; what it is, what causes it, and how to cure it. Due to the endless dearth of variables inherent in R/C model aviation, it is somewhat futile and very misdirected IMHO to blame any manufacturer for perceived shortcomings in their product, especially in the area of this discussion thread. An F-117 Stealth Fighter was brought down by aileron flutter in front of an airshow crowd. Looking at the tapes of the crash in slo-mo reveals flutter starting at the tip of the left wing/aileron. Do we blame the manufacturer or do we blame maintenance.....?

My DP300L will be powered by a YS140DZ, and will be "beefed up" per this thread.

Test pilots sometimes pay a hefty price to "get the bugs out" of new equipment. The best the rest of us can do for or say to them is "Thank you for your experiences in learning the lessons by which the rest of us benefit"; and "So sorry for your misfortune".

Chuck E.

Dave Patrick 330L Aileron Flutter
 

Its just a thought but I know on mine the ailerons are built up and not sheeted. They twist VERY easily from end to end and it seems to me that no matter what servo and linkage you use there is still great potential for flutter to start out near the wing tip without a second servo being installed or the aileron strengthened.

I don't claim to be an expert on the subject but it just seems to make sense that this would happen if the surface is long and flexable. If you stick something like a piece of paper out the window while you are driving it will flap in the wind. Something rigid on the other hand won't. I could be wrong though.

Dave Patrick 330L Aileron Flutter
 

Hear, hear! Terry is right. An aileron that long that flexible is just asking for flutter.

Yikes.
 

Ed,

I need to make clear that I never intended to imply "it was THE GASSER!!". A large engine that an airframe was not designed for can easily be a contributing factor, and that's all I was pointing out. Obviously, there are many factors that can cause flutter, but it does not happen for no reason. There was something wrong with every person's plane that is experiencing flutter, and it is not a general design flaw or everyone's DP 330 would be having the problem.

If everyone that has had the problem could be as specific as possible about their installation, the root of these problems could probably be deduced. Michael Glavin's questions are some of the questions that need to be answered in all of these cases to help detemine the cause.

Ed, you stated in your first post "and started a few low speed (1/2 throttle) passes to trim her out". From my experience with my Extra 1/2 throttle was far from low speed. My plane had unlimited vertical at 1/2 throttle and would be going very fast when level if I maintained 1/2 throttle. I assume yours had similar performance with your BME. Maybe your slow is my fast. That's pretty subjective and we'll probably never know.

Terry has suggested that the built up ailerons might be the problem. I don't think that this design is the problem as virtually all giant scale planes have built up ailerons, but maybe there is a wide range of stiffness of these ailerons as they are built because of variation in wood density or some other build factor. It might be an interesting idea to explore.

Dave Patrick 330L Aileron Flutter
 

I agree that many planes big planes have built up ailerons but all of them that I have looked at since wondering about this potential problem in my 330 have turned out to be much stiffer than the 330 that I have. They have also all been either solid, foam/sheeted, or built up and sheeted. Could be that its just my kit but I doubt it. I tried to find similar sized planes (Sig Sukhoi, Lanier Caps, a few different Ohio RC kits) all of them had much stiffer surfaces.

The other thing I noticed is that on most of the other planes I looked at the wing servo mounting point was in the middle of the control surface and on my 330 its mounted fairly inboard (again asking for flutter at the tips).

Now I know alot of this is guessing but when my 330 takes off for the first time it will be with 2 servos per wing and you won't be able to see through the ailerons.

Again...I'm no expert...just my 2 cents.

Dave Patrick 330L Aileron Flutter
 

dirtybird: Please explain the $10 flutter fix...

I just ordered a BME44 for my DP Extra. I too wonder why an additional alieron cutout wasn't provided. Hacking a hole for another one is not something I like to to with an ARF. I build kits in the Winter, and I don't like to use up "outdoor" time on this kind of stuff during the Summer months.

Dual aileron servos
 

Adding two aileron servos will probably prevent the flutter, but they are definitely not needed on this plane as long as you have good hardware, have them properly setup and a strong servo with metal gears.

It would be really interesting if there was some way to compare the stiffness of a variety of samples of ailerons from this plane. If there is a problem with some of the ailerons, the dual servo "workaround" should prevent the problem, so that is one way to go about overcoming the problem, though I personally think is overkill.

People may recall, the 33% H9 Extra 330 had the same problem and went to two ailerons per wing. They did this as a quick fix to get around the small percentage of people that were having problems, as in this case. In fact the majority of the planes flew fine with one servo as long as you put a strong enough servo in with good hardware and setup correctly. Sound familiar. I happen to have one of these with single Hitec 5945's and it works great. These ailerons are much bigger than the ones on the DP Extra, and a single servo works fine, but I have no way to compare relative stiffness since I don't have my DP anymore.

Dave Patrick 330L Aileron Flutter
 

I agree with you Bill. Two per wing is probably overkill here if you use a strong enough servo and linkage.

I'm basically doing it because I already have a pile of very expensive 4721's and don't want to buy something different and also because of reports of people losing this plane with similar gear. The soft ailerons on my kit make me a bit nervous too.

I have personally talked with at least five guys running 2.4 and above engines with 100 oz or greater servos and solid linkage that have had NO problems under any conditions. They all however had early releases of this kit so maybe the more recent ones have soft ailerons???

The extra servo for me is just extra insurance.

Early releases?
 

Hi Terry,

>>They all however had early releases of this kit so maybe the more recent ones have soft ailerons???

That's a very interesting thought. Mine was one of the first releases too. I know they made changes to try to get the weight down on the plane in later releases. I wonder if they're using less dense balsa now.

>>The extra servo for me is just extra insurance.

...and it should do that. I'm sure you will, but make sure and report on your results.

first lot
 

Sorry to hear about the failure Ed...

I have not finished assembling it yet, but my DP extra came from the first boat load. The ailerons are pretty solid.

I'm following this thread intently to make sure I dont have any problems. OS160 with turbojett going in it.

Bob Brassell

G5
 

Davham,

It is true, I called several months ago when I first bought the airplane. I did not get to speak with DP directly, I spoke with I guess Sandy. She did not know how the g45 would be for the extra, so she took my name and phone number to call me back after she asked Im assuming DP or other knowledgable person. She called me back within 20 minutes or so, and told me to go ahead and use the g45 with CA hinges! It was OK! So, with that answer from DP models, I mounted up my G45.

DP's Fix
 

This right here shows that DP MAY know there is a potential flutter problem

http://www.davepatrickmodels.com/dpm/extra/notes.htm

cbk

Dave Patrick 330L Aileron Flutter
 

Bill,

You know what, I think the Stiffness issue maybe to blame. I didn't really pay too much attention to the ailerons (as they were covered), but they were VERY light and rather flexable come to think about it. I wonder if the planes with FLUTTER maybe had a batch of REAL SOFT ailerons... My hardware setup was SOLID as they come!! Hangar 9 alum arms, Dubro 4-40 Ball links, 1/8" rods (made with the Rod Chuck).. Klett hinges and the gap was sealed.. If the suspect ailerons are way too flimsy, at that size there is no WAY even one servo would stop the RIPPLE effect as flutter sets in.. As for the speed, it was SLOW..The motor was brand new and running very RICH... I fly many different Aerobatic aircraft..She was nowhere near HIGH SPEED..Believe that..and yes, you are right about your FAST vs my FAST!! Think about it, you can have the most solid hardware setup, but once that aileron starts to flutter, it is just going to rip it up period!

Just thought???
 

The aileron flex thing sounds like a possibility, but Im wondering about the hinges?? Davros, you used Klett hinges, are those points or flats? Are they plastic or CA Fabric?? Either way, did you epoxy or CA them in. Just curious, as these arf kits do not have the meat in the trailing edge install hinge points! The CA higes are usually the best way to go, unless you install hinge blocks behind the trailing edge of wing ect. In any of the flutter cases, were the hinges ripped out??

Dave Patrick 330L Aileron Flutter
 

The Kletts are Flat hinges (plastic with pinn) and they were epoxied in...they did not rip out

Dave Patrick 330L Aileron Flutter
 

So if I use two aileron's, do they need to be matched, and are digitals necessary to do this?

It's gonna be a pain in the butt since the wing is already built and covered, but after all Ive heard, and after experiencing aileron flutter strip a servo on my electric E3D last week, I'm not taking any chances.

Anyone have any pointers on how to add the second aileron servo? In the photo on the DP web site it looks as if that second servo was installed before the wing was covered (Hmmmm). There is no sheeting under that area on my wings. Am I going to have to cut the covering from that entire bay and install sheeting and then scab some covering onto that nice looking new wing?

GRRRRR.....

Dave Patrick 330L Aileron Flutter
 

You don't need two aileron servos with the related headache and weight. There are easier methods to address the problem.

First off, verify the ailerons are suspect. If you feel they are build new ones or beef yours up... You could sheet them or you could add carbon fiber strips the length of the surface. If you do add a second servo, related components, supports and open the aileron and add some structure/support to mount and additional control arm you'll add substantial weight... I'd guess at least 10ozs. realistically...

Use standard size metal gear servos, 4-40 hardware, rigid control push-rods, rigid control arms [such as Rocket City], HD servo arms and lastly be sure you don't make the mistake of using a servo arm that is longer than the combined total of the control horn and the surface. Measure you servo arm pivot points center to center, I used 1-1/4" servo arms. Measure your aileron from the hinge center line or pivot point to the pivot point of the control horn. Your looking for approximately 1-1/2" total. Anything equal to or less than the servo arm is UNDESIRABLE. :eek:

Dave Patrick 330L Aileron Flutter
 

i am surprised so many people are having trouble. I have a bgx 2.1 which pull its vertical and i used only 1 futaba 9303 with just 80 ozin of tourqe but i did change the linkage hardware to 4-40 and if i fly full throttle flat and level which even with just a 2.1 which some argue is too small for the plane but i can still hover i have no flutter. I have the first run kit and i am surprised this is such a problem because all i know is i have 1 80 oz servo on each aileron with no flutter for abotu 75 flights now

Dave Patrick 330L Aileron Flutter
 

I really would rather not waste Summer flying time to hack up my wing and add a second set of servo's. Where can I obtain Rocket city hardware, and which part numbers do I need? DP says that the structure was not designed for Rocket City hardware.....

BTW: I "split the difference" and added another CA hinge between all the provided hinge slots, for a total of 9 CA hinges on the aileron's.

Thanks for the feedback.

Dave Patrick 330L Aileron Flutter
 

Ed:

It definitely sounds like you had yours setup right, which makes the soft aileron theory look pretty good. It definitely bears more investigation. Anyone else have flexy ailerons on theirs? Is it a new or early release.

cbk07:

Interesting tech note. It looks like Dave is covering all bases the same as H9 did with the Extra. As Michael Glavin just posted, I agree completely with him that dual servos are unnecessary. Follow his advise on stiffening the ailerons if necessary and make sure you have the proper geometry for the servo linkage and I think you have absolutely nothing to worry about....with of course a strong servo and linkage as mentioned before.

BTW, mine had the CA hinges and I did use the Sullivan control horns supplied in the kit without any problems.

Dave Patrick 330L Aileron Flutter
 

Dave Patrick is right, the Extra was not designed for the Rocket City hardware. However it's very easy to modify the aileron and elevator surfaces to accommodate them. On the the link below I have some notes on the hardware used and method to install it.

http://mglavin.com/Extra330lreview.html

Since I originally assembled the Extra I modified it. I installed Gene Payson's carbon gear troybuiltmodels.com., never had problems with the stock gear just a little heavy, moved the tiller bell-crank, throttle and choke servos into the belly, replaced the tail wheel assembly out of necessity. Saved some weight and removed the 6ozs. of lead I had installed to make it 3D to my liking.

This model is wild child on high rates be careful....

Rocket City hardware is currenty available from most hobby shops and direct from the new distributor Nelson Hobbies www.nelsonhobby.com.

DP Extra 330L ailerons
 

I'm flying a DP Extra 330L with a Taurus 3.2 ci engine and Zinger Pro 22x8 prop with no problems with flutter. I have 9 Dubro pin hinges per aileron and the plane weighs about 17 pounds but flys very well at this weight. I have unlimited vertical but with this prop and about 7K rpm the plane does not fly real fast. I don't use full throttle very often.

I'm currently building another DP Extra 330L for a friend. This is from the latest batch I think (received new DP Extra a couple days ago from Quantum Modles). The weight of the assembled Extra less engine, flight control system and most hard ware is the same as my first one (9 lb 6 oz) so they didn't make it any lighter. This new Extra will also have a Taurus TS52 gas engine but have all JR servos and PCM receiver. Mine has Hitec HS5645 digital servos on all flight surfaces and HS225 for throttle and choke.

I did notice in the new manual a page was added showing two aileron servos on each wing panel but wasn't drawn to scale or give any info on how to do it.

I like my DP Extra 330l, it flys very well and lands easier than most trainers IMO.
Evert

Rocket City Hardware usage on 330
 

As I mentioned earlier, I have installed Rocket city hardware. I just reinspected one of my ailerons and my install. Like it has been said, there is a piece of ply for mounting the sullivan horn to, and there is a balsa block under the ply. This balsa block, fills the entire space "top and bottom" of aileron between the sheeting. So, in other words, you have solid area just uder he ply! When I installed the Rocket city hardware, I drilled the hole for the horn screw (8-32) and I filled that hold full of 2ton 30 minute epoxy. I the screwed in the screw till the screw would no longer go. I did not penetrate the top of aileron. After reexamining this area, I feel that it will be fine! That solid block of balsa with epoxy reinforced should do the job! I would be more concerned wth the Sullivan horn, as it only uses 1/2" screws (i think 1/2") for mounting I would think they would not have the strength of a 8-32 screw mounted in 1/8" ply and sunk into a balsa block with well over 1" or 1 1/4" of screw. This is only my opinion, but I really feel it will be adaquate!