gnirwin

My Feedback: (25)

I picked up a used Funtana 90 that I flew for the first time today (the plane had about 10 flights on it) and I flew the first flight with no problems, mostly just trimming the plane. I refueled and took her up a second time and did some nice rolls and a long inverted pass down the field, very nice. I then brought her back down the length of the field on a low pass, 1/3 throttle and the airleron flutter was extreme. The flutter was so bad that I brought the plane down immediately and forced the landing a little. Another weakness in the plane bit me, the landing gear broke off. The gear had been torn off by the previous owner and he didn't try to beef them up. I will beef them up because the landing was not perfect but the gear certainly shouldn't have come off. The flutter is what is bothering me though. Does everyone experience this? I know the plane is not meant for high speeds but 1/3 throttle is about as slow as I like to fly. The previous owner did seal the gaps but not the way I would have done it. He ironed the gaps all the way down to the pivot point of the hinges (where the CA hinges are) and back up. If you look at the wings it doesn't look like they are sealed but they are. I will be resealing them a little bit differently. The servos in the wing are Futabas 3010 with a 6 volt system. Are stronger servos the answer here? Right now I'm not that happy with this plane.

racer8297

My Feedback: (13)

Hi Gnirwin,

I have had 2 Funtanas (still have the second one) and I love them. If you do a search on RCUniverse you will find a thread that talks about the mechanical setup of the servo control horns, linkages and control surface horns. I can't tell you how important the setup is on this airplane. The servos you are using are what I would call minimal but usable. But if the mechanical advantage of your setup is not right, you will have trouble. Another thing to check is the mounting rails for the wing servos. I cut the bottom of my wing open and beefed this area up a bit. Both my models were the early version but I think that Hangar 9 beefed this area up later on.

FYI, my first plane lost 1 aileron due to sudden and extreme flutter but was landed safely. Horizon replaced the wings in 2 days free of charge. Then, I completely lost a wing due to the wing bolt coming loose (my fault). This totaled the model. I liked the plane so much that ordered another one the next day. And I still have it, knock on wood.

Regards,
Jim

George E.

My Feedback: (16)

I flew my F90 hard all last week with 3010's in the ailerons, no flutter even at high speeds. I don't seal any surfaces since I don't think sealing solves flutter, just an opinion. The only problem I had was breaking off my rudder during a snap.

I do have the "new" F90 with the improved aileron servo mount. The original version had the servo tied to one rib and the new version has the servo sandwiched between two ribs. I believe the old version had the aileron flutter problem.

Not24

My Feedback: (1)

George! What engine did you end up using in your Funtana? My 1.08 is only barely adequate for a ten pound model. My airframe is now hanging on the wall in the garage, waiting for a better powerplant. I know the s 150 is the ticket, but I'm a 2 stroke guy, leaning towards the TT120 pro.

K.O.

My Feedback: (16)

Gnirwin
I have about 40 + flights on my F90 and I've not experienced any control surface flutter. ( how ever I'm weary of it happening). As I get more flights and confidence builds, I push the envelop more and more. So far no problems. My OS 120 gives me unlimited vertical so from take off I like to go up a few hundred feet then spin it down ( high control rate and throttle way back) but at pull the plane is still really moving but not a hint of control flutter. I don't have gap seals but I when I installed the control surfaces I kept the gap to a minimum. I have Hitec 635's on the ailerons, elevator and a 625 on the rudder. I also use the ball bearing type push rod connectors to keep control linkage play to a minimum. The 1st place I'd look is your linkage and check your servo bearings. This plane has big control surfaces and and any play in that area can set up flutter in a heart beat.
K.O.

gnirwin

My Feedback: (25)

I checked my wings, I do have the "old" original design. This flutter was extreme and honestly it was the worst I have ever encountered. After my post earlier I have inspected my wings and servos only to find one of the airleron servos has stripped gears. I will be cutting the wing open and making major modifications to the servo mounting blocks. I also am going to replace the servos with Metal geared ones. The servos already have heavy duty ball bearing style hardware. I am going to also beef up the LG considerably.

MustangAce

My Feedback: (3)

I heard of an account at my flying field where a guy had flutter lost control and crashed in the trees!

He found out that both aileron servos had been stripped. Not sure if it was the early one or not.

jeang

I have roughly 25 flights on my funtana90 with a OS 1.60FX 2S and Hitec servos 5645 all around with no flutter problems , i didn't seal any hinge gap but i did loose my rudder in a blender today[]. This plane is a very
good plane when u have lots of power. I can do anything i want with that plane except i can't go on full trottle

Bye Carl

George E.

My Feedback: (16)

You need to beef up that servo mount. Tacking it to the side of one rib is not enough, as you found out. H9 realized they had a problem and did a redesign.

George E.

My Feedback: (16)

Not24

Webra 1.20 with pitts muffler. I got both for $130 used in great condition. I run an APC 17x6.

If you are buying new I'd go with the YS 1.10. For the price of a Webra, muffler, and Cline regulator (if you want the tank on the CG), you could have the YS.


Guys are putting larger motors 1.50, 1.80 1.60 on the F90 and they work great too.

tIANci

My F90 had the YS110 turning a 16x6, totally fun to fly. It will only flutter if you push the throttle on level flight, be sensible, I fly at only 40% throttle in level flight.

Canadian_Eh!

Not 24 . I put a supertiger 2300 in mine and had a verticle drag race with my friend who has a saito 150 and they were both equal and my supertigre only had 2 17 oz tanks through it at that point, and as a plus this engine is dirt cheap for the engine class its in.

George E.

My Feedback: (16)

I guy in my club also has a supertigre and he loves it. Big and heavy but cheap.

Spoiler

I nearly lost mine to flutter as well! Check the aileron control horns. In my opinion, based to some extent on observations with different F90's at our field, the stock aileron horns are probably the worst culprit. They are very flexible and I am sure caused the flutter on mine as the speed was also low. The other variable is the pitch of the prop. Altho your speed may have been low, the airflow off a too high pitch prop could be a factor.