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Composite ARF Impact problems? - 4/26/2005 2:38:52 AM   
wizardfs


 

Posts: 1
Joined: 4/25/2005
From: , TX, USA
Status: offline 		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.
       Post #: 1

RE: Composite ARF Impact problems? - 4/26/2005 3:24:40 AM   
BrianB


 

Posts: 263
Joined: 3/25/2002
From: Orange Park, FL, USA
Status: offline 		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.

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Brian Billings

(in reply to wizardfs)
       Post #: 2

RE: Composite ARF Impact problems? - 4/26/2005 5:18:41 AM   
Derek.Koopowitz


 

Posts: 352
Joined: 2/27/2004
From: Benicia, CA, USA
Status: offline
quote:

ORIGINAL: 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.



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?

(in reply to wizardfs)
       Post #: 3

RE: Composite ARF Impact problems? - 4/28/2005 1:33:17 AM   
MikeEast



Posts: 3226
Joined: 10/18/2003
From: Nederland, TX, USA
Status: offline 		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.

< Message edited by BigNed -- 4/28/2005 1:41:47 PM >

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RCU Reviews
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       Post #: 4

RE: Composite ARF Impact problems? - 4/28/2005 7:06:15 AM   
KeithB



Posts: 542
Joined: 1/6/2002
From: Garland, TX, USA
Status: offline 		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

(in reply to MikeEast)
       Post #: 5

RE: Composite ARF Impact problems? - 4/28/2005 7:09:26 AM   
KeithB



Posts: 542
Joined: 1/6/2002
From: Garland, TX, USA
Status: offline 		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.

(in reply to KeithB)
       Post #: 6

RE: Composite ARF Impact problems? - 4/28/2005 12:14:31 PM   
MikeEast



Posts: 3226
Joined: 10/18/2003
From: Nederland, TX, USA
Status: offline 		Check your PMs....

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RCU Reviews
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       Post #: 7

RE: Composite ARF Impact problems? - 4/28/2005 1:17:09 PM   
toysejr


 

Posts: 39
Joined: 2/7/2003
From: Fort Worth, TX, USA
Status: offline 		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



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Flying is inherently unforgiving. Lift and thrust are temporary but gravity is permanent.

(in reply to wizardfs)
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RE: Composite ARF Impact problems? - 4/28/2005 1:22:50 PM   
50%plane



Posts: 3765
Joined: 3/8/2005
From: x, , USA
Status: offline 		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.

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       Post #: 9

RE: Composite ARF Impact problems? - 4/28/2005 1:37:53 PM   
PeterP



Posts: 339
Joined: 2/17/2003
From: Brisbane, AUSTRALIA
Status: offline 		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


(in reply to 50%plane)
       Post #: 10

RE: Composite ARF Impact problems? - 4/28/2005 2:57:05 PM   
PeterP



Posts: 339
Joined: 2/17/2003
From: Brisbane, AUSTRALIA
Status: offline 		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

(in reply to PeterP)
       Post #: 11

RE: Composite ARF Impact problems? - 4/28/2005 3:57:47 PM   
tommy s


 

Posts: 1202
Joined: 1/14/2004
From: houston, TX, USA
Status: offline 		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

< Message edited by tommy s -- 4/28/2005 10:46:50 PM >

(in reply to PeterP)
       Post #: 12

RE: Composite ARF Impact problems? - 4/28/2005 11:22:41 PM   
67685


 

Posts: 172
Joined: 8/20/2004
From: Nannestad, NORWAY
Status: offline 		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

(in reply to PeterP)
       Post #: 13

RE: Composite ARF Impact problems? - 5/3/2005 1:24:44 AM   
MikeEast



Posts: 3226
Joined: 10/18/2003
From: Nederland, TX, USA
Status: offline 		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

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AMA793948
RCU Reviews
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RE: Composite ARF Impact problems? - 5/3/2005 3:36:04 AM   
byoung466



Posts: 477
Joined: 7/12/2002
From: tulsa, OK, USA
Status: offline 		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.

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Brian

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       Post #: 15

RE: Composite ARF Impact problems? - 5/3/2005 12:09:20 PM