Pete S-RCU

I built a ziroli Panther in 2005.
Great flying plane, had am 18lb thrust turbine in it.
Last spring I put a new engine in it, 22lbs thrust.
Had about 7-8 flights on it, when I was making a full throttle pass when I heard flutter.
I throttled back, had aileron control, but almost no elevator.
I killed the engine and it went in.
I'll get the engine back soon, and am thinking of building another Panther.
I'm thinking of reinforcing the tail section with carbon fiber rods and maybe even covering the plane with a light carbon fiber cloth.
Anyone ever done this, and where is a good place to buy the rods and cloth?

None of the threads I've looked at have mentioned reinforcing the plane, as it was designed for a ducted fan originally.

Any thoughts on this, has anyone tried it?

I knew I was pushing the limits with this plane, it seemed to be taking the additional power ok, but I found the limit the hard way.
I did add extra structure in the wings and the fuselage center section.

NickC5FE

My Feedback: (31)

If I recall when I built mine, the plans had the v.and h stab built with balsa stringers. We used a harde wood, I think maple. Worked fine !

rhklenke

My Feedback: (24)

Pete,

There are a number of those planes around flying with turbines. However, it was only designed for around 12 lbs thrust from an ICDF and some early turbine conversions used 12 lb turbines and it flew fine. 18 lbs of thrust is plenty for that model and 22 lbs is *more* than enough. If you were doing a full-throttle pass with a 22 lb turbine, I'm not surprised at all that it came apart. If you went with the stock setup of servos connected to the tail surfaces via long pushrods, then that would be even more likely.

I have one that I blew up to 80" wing span and I fly it with a P-120. However, the airframe is glassed with some extra layers around the tail, I use JR 8411 servos that are mounted right at the surfaces with 3" pushrods, and I manage the throttle very conservatively.

Hardwood stringers in the tail would help, or at least select hard balsa for the tail stringers and skin. Be careful not to get the tail too heavy - one extra ounce there means about 1.5 oz in the nose. Also read the threads about the wing incidence and possibly reducing it some for a purpose-built turbine version of the plane.

Bob

Pete S-RCU

I was aware of the danger, but I'd been sneaking up on it slowly.
It would fly all day at full throttle with the 18lb'er.
It had 5411's in the tail with 3 inch pushrods.
The servo's, push rods and linkages were all OK after the crash, not much else left to analyze though.

Do you remember which posts were about the incidence?

rhklenke

My Feedback: (24)

Yea, unfortunately, flutter is kind of a nothing or all thing - as you found out. Up to the critical speed, there is no indication, and then all of a sudden, it happens, and again, as you unfortunately found out, the first onset can be completely destructive. Lots of full-scale pilots have gotten killed by flutter...

The incidence issue with the Ziroli Panther was (re) discussed here: [link=http://www.rcuniverse.com/forum/fb.asp?m=11261732]http://www.rcuniverse.com/forum/fb.asp?m=11261732[/link]

Bob

Pete S-RCU

Thanks Bob,
My Panther did climb, I had trimmed a little down elevator in so it wasn't really a problem.
I will do a little more research, before I build the next one.
Bouncing on landing was a problem, had to get it really slow to stay on the ground.
I finally used a lot of flap, and that slowed it down so it landed pretty good at the end.

Pete S-RCU

Good idea, I was thinking of carbon fiber spars in the stab and rudder if possible.
CF doesn't bend, so it will only work where straight sticks are used.
I was also thinking of running some from the tip of the vertical stab to the crutch in the fuse.
That should stiffen up that area pretty good.
And, anywhere else I can fit it in.

john491

My Feedback: (13)

I have found it more effictive to use carbon sheet goods (.5 oz carbon mat) to do the finish in place of fiberglass. I got mine from BVM but I'm sure there are lots of other sources. The monocouque layup with carbon mat is as strong as rods and extends across the entire surface instead of only one direction as with a rod.
Mine is also covered with FliteMetal so that may be keeping down the possibility of flutter in my stabs.
I'm running a Cheetah so I'm over 1:2 and have had no trouble even at full steam, but I may not be fast enough yet to flutter.
John

Pete S-RCU

I was considering CF fabric, didn't know where to get it.
Does the direction of the orientation of the weave matter?
Is it equally strong in all directions?
Right now, just considering a lot of options, don;t want to lose another one, but I do like to go fast!

john491

My Feedback: (13)

The carbon mat I used was omnidirectional. I think Dreamworks may also carry it as well as BVM. I used it to cure a stab flutter I had in an F-86 at high speed. The flutter was bad enough to break one stab off in flight. Made for an interesting finish to the flight and landed safely. The carbon mat on the top and bottom instead of woven glass cured the flutter. At least at any speed I was able to reach.

John

Pete S-RCU

Thanks John, I will check it out.