wizardfs

Anyone having problems with this plane. Ours had the tail section of the fuse fail in the first few flights even with the crutch installed as requested by manufacturer. The only thing they would do is send us an updated version for an additional $400. Didn't seem like much of a deal to me, putting good money after bad. Our plane wasn't abused, just flown through typical pattern manuvers, not even any snaps. It failed just ahead of the stab. We're real lucky to have gotten it back on the ground. I'm just wondering if anyone else has had a similar problem. No doudt, I don't recommend the airplane OR the company.

BrianB

My Feedback: (2)

Do a search, just type in "Impact" and make a pot of coffee, you will get some reading material to last awhile. Some post are about your problem, others are about how to build it so it won't happen and some are on how well they fly. My second Impact is flying great.

Derek.Koopowitz

Did you use the factory supplied crutch or did you make your own? How about wing adjusters? Did you use them or did you use the factory method of installing the wings? How about rudder? Did you use the factory rudder with the factory supplied hinges or did you go with different ones?

MikeEast

My Feedback: (3)

I saw one fail today exactly as has been described. It will be interesting to see what Composite ARF does. Split right down the seam of the vertical stab to where the stab transitions into the fuselage and snapped all but about 1/4 the way around the fuselage just in front of the vertical and horizontal stabs with a loud POP. Its a shame,, the plane flies GREAT.

KeithB

My Feedback: (1)

Was that Buddy's Impact?

Dude, this is really scaring me! I've got mine ready for paint, guess I shouldn't spend too much time making it look good [:-]

KeithB

KeithB

My Feedback: (1)

Just thought of something. I always thought the name Impact was a bad choice, just seems like bad karma.

But given the troubles, maybe they should have called it the Imcrack, or Imsnap.

MikeEast

My Feedback: (3)

Check your PMs....

toysejr

I was at the flying field when this one came a part, I thought I saw the stab hit the fuse serveral times. The pilot got lucky that it stop fluttering enough in time to land it.
It is sure a shame that Comp Arf is not taking care of this..

-Toyse

50%plane

My Feedback: (5)

I have heard many storys about poor planes coming from comp arf and their not backing up their products that I will never get one of their planes.

PeterP

Hi all,


Most of you would be aware that a number of Composite ARF "IMPACT" have failed from suspected rudder flutter.


I raise a couple of questions to this forum;


I know that the purpose of counterbalances are to reduce the loads on servos and linkages in our application but what are the side effects.

Can a rudder counterbalance create undesired torsional stresses on the fuselage?

Can a poorly configured and tensioned pull-pull linkage to the rudder be more susceptible to flutter if the rudder has a counterbalance?

What other types of forces are at play with counterbalances?

I am just trying to find a reason for the relatively high failure rates against this design.

It is the same old thing- why are some people having problems and others don't. (Similar story to 4-stroke exhaust headers)

I will be test flying my model soon so I am obviously concerned.

Regards,

Peter

PeterP

Someone has suggested that it is a rudder weight issue.

If models are failing with the crutch installed that dispells the theory of the fuse sides buckling.

Would it be possible for everyone who has had a model fail to post the weight of their rudders. That is if there is anything left. Please mention if hinges and horn are still attached.

The weight of my rudder with horn is 65grams - I havent flown it yet but I thought I would post this to get things started.

Hopefully we can get to the bottom of this.

Peter

tommy s

My Feedback: (55)

Maybe it's not the fact that the airplane is made of composite material , maybe it's
the size of the control surfaces causing the flutter. The movable control surfaces on
most airplanes are way bigger than they need to be in my opinion. I know on my
Excelleron the movable surfaces are huge and I have them moving very little to
execute the maneuvers in a pattern flight , they could be much smaller and still function
well. It seems a lot of manufacturers nowdays are designing planes to fly pattern and 3-D
, so they design bigger control surfaces when smaller ones would do just fine. I'll bet
everyone who flies R/C has seen what flutter can do to an airplane.

I see a lot of 3-D models at the field where I fly experience horrible flutter with terminal
results , probably because of excess speed with their huge elevators, rudders and ailerons.
I have an older pattern plane, an Illusion with a MVVS .91 , and the surfaces on it are about
1/2 the size of the ones on my Excelleron and even at that size are very sensitive and move
very little. Maybe the answer is as simple an downsizing the control surfaces and really
slack free linkage with good mechanical advantage.

tommy s

67685

Hi,

My Impact are ready for test-flight next week,(together with two more Impacts in my club) and it will be interesting to see what happen ... I have gone my truly old fashion way with the light-weight build-up rudder (46 gram with horn) and traditional in-line hinges (5ea). I also put in a horizontal webb in the fuselage like my other pattern bird, mounted the rudder servo in the tail ( bennefit from the rudder weight saving) like i have been using for the most of my pattern birds. Cg went out just fine with 3 servos in the tail.

I have seen this fatique problem in other pattern-birds also, caused by improper linkage setup... When corrected, everything went just fine. Luckily we got the chance to investigate and correct everything before it was to late...

hmm, time will show how everything works...

Kjell Olav

MikeEast

My Feedback: (3)

Mine failed last wednesday. This airplane has logged over 100 flights with no problems. It was one of the early kits built last august it has pull pull rudder and a single elevator servo with Central Hobbies carbon fiber pushrod system for elevator
The seam from the base of the rudder fin to the top and one side of the rudder post came apart there was no seam tape on the internal seam. the airplane was flying straight and level when the failure occured. The fact that flutter initiates these failures may be true but the ultimate reason for the failures is lack of air frame strength which in my opinion is the results of poor design and/or failure to provide adequate support in the tail area which allows the fuselade to oil can when just the right force is applied in the direction that causes the fuselage to kink in or twist to the point of failure.
I havent been able to contact Composite-arf or my sales rep to date they don't answer my post's
For all those who are flying these airplanes I think you have a ticking time bomb unless you have modified the airframe to carry the load which is very difficult to do after the plane is built.
I think more ao these have failed than a few It wiold interesting to know how many.
Buddy

byoung466

My Feedback: (16)

Buddy did yours have the internal formers installed or a crutch.
Were you going fast when it broke? Wing adjusters or the fixed pin for the wing?

Just curious.

MikeEast

My Feedback: (3)

Hehe... I obviously forgot to log off at Buddys house...

Mike

B. Brammer

Brian
No it has no former or ladder frame. I had just rolled out of the bunt manuever wind was about fifteen MPH blowing out. I think the combination of right rudder and up elevator during the roll out provided the stress that resulted in initiating the failure but the actual failure occured in atraight flight when I powered up for the double embelman at the center of the box. This airplane has been flown on a regular basis in four or more contests over a period of eight month's including many practice flights.
I think that the seam in the vertical fin opened up on the left side first due to the absence of seam tape required to strengthen the joint allowing wind forces to enter the opening which initiated the failure. The rudder pull-pull is perfect, absolutely no slop, elevators the same no slop.elevator push rods are supported by a ladder frame which is secured to the top of the stab tube in the rear and several cross members in the fuselage. all of these are still in place leading me to believe that the failure was not a hormonic vibration or flutter but a side force which caused the fuselage to oil can to the left as indicated by the compression ripples on that side versus tension cracks on the right side again leading me to believe that failures are only experianced when the exact forces are combined to reach the critical design limits of the airframe.
I was as in other cases able to land the airplane without further damage and would like to locate someone who has successfully repaired one of these to find out if repairs are possible and how they did it.
Also I would like to hear feed back from those who were able to get a response from Composite-ARF
They state that there are over 350 sold with a few failures, but it looks like there are more than a few, I wonder how many? Seems to me that they should do something to help those who suffered the loss that was due to their inadequate design. I guess we will see what they are made of before this is over.

This is a sweet flying design in every respect and I would like to be able to fix it but havent figured out where or how to start.
Buddy

BrianB

My Feedback: (2)

Buddy, I gave Matt K. my old fuz and he was going to repair it, after evaluating it for a few weeks he felt it would be very difficult to repair due to the type of construction. You may try and contact him and get his personal toughts on the matter.

As far as how many have failed I personally know of four Inc. yours, Matt K. talked to some others that had failures overseas

tommy s

My Feedback: (55)

A fellow on another thread from Algester Australia , poster name - "Dauphin" , was discussing
repairing the fuselage on an OTOP , which is the same material as the Impact as I understand it.
Maybe he could tell us how he did it.

tommy s

birdie_in_texas

My Feedback: (2)

so comp arf is ducking their heads on this one..? as expensive as their planes are, you would think they would jump up and replace this as soon as possible..

i know of at least one plane that is going to be at all the pattern meets with a very unflattering sign on it (including the nats)...


i suck too bad to get an eggshell plane anywyas..it would die before the maiden..

PeterP

A fellow on another thread from Algester Australia , poster name - "Dauphin" , was discussing
repairing the fuselage on an OTOP , which is the same material as the Impact as I understand it.
Maybe he could tell us how he did it. Dauphin never fixed his. The fuse is a write-off.


Cheers

Peter

toysejr

Here are some pictures:

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Eggert

Hi Gents of the truly lovely pattern world !

I see a lot of mails regarding the Impact and the apparently weak tail section, but I do not see so many descriptions of what linkage that is being used for the rudder. To me, it seems a poor solution to use the suggested pin hinges, that are not supported for the first 10 millimeter going out of the rudder post, since this could cause flutter in the rudder.
I know it won't bring your aeroplane back in good shape but did you use the above solution ?

I am considering to order one Impact myself bacause I think it holds the overall best price/ quality to market right now.

Let me know what you think

Best regards Beetlejuice

50%plane

My Feedback: (5)

Composite ARF=expensive CRAP

tommy s

My Feedback: (55)

Beetlejuice,
I don't think that is the solution my friend. I don't know what everyone else did but
I have personally seen Buddys airplane and it was built by a master builder who did
not install the rudder per the instructions. There is no slop or unsupported hinges on
his airplane.

tommy s