It still bothers me is not knowing, for sure, why the failures have occured.
I fly my IMPACTs with George Asteris, he had built two for himself and aligned two for me. We put the rear former in, as advised, in all of them. I went further and installed a rear fuselage lengthways "ladder" in both of mine.
George flew his a lot more than I did this year, No sign of any failures. Gerge destroyed his first two in two different ways. The first was due to a dead-stick DZ in a strong down wind position. Hit the hill on the way back, hard. No damage however in the area that has been failing. The second one had a mid-air with a BIG vulture. Destroyed the plane but still OK in the "danger-zone".
(George is a renowned designer and pattern builder. I mention this because he has now almost finished his third IMPACT. The plane must have impressed him a lot for him to make three for himself.)
My two Impacts have been FAI'd and Master'd with multi snaps and flown in tough wind conditions. Still holding up.
Where I am going with this story is that braced or not ALL of these ones held up. Yet some others have sadly and clearlly failed. (I forgot to mention that all of ours have light balsa/foam rudders).
I have put up a bunch of theories on this forum, but they are only theories. I can neither condem the supplier or exonerate the plane.
Do we have any new theoreis or ideas out there as to why some have failed and the rest have not?
Curious as ever - Eric.
quote:
ORIGINAL: BillB
Hello Magne,
I had installed a rear former and a horizontal plate, just as is recommended in CARFs update on their website. I also had installed a bulkhead directly behind the canopy. From that bulkhead to the rear former I installed a 1" thick piece of foam horizontally. It was glued to the sides of the fuse and to the former . The break in the fuse was right at the former. The glue joint between the former and the foam stiffner had not broken all the way through. I had my elevator servo mounted between the wing. Except for using a bellcrank in the tail with pull pull cables back to the servo, and real Robart hinge points, the tail assembly was stock.
[image][/image]
< Message edited by Eric.Henderson -- 10/3/2005 4:57:13 AM >
Posts: 61
Joined: 7/15/2002 From: Mt. Prospect, IL, USA Status: offline
Only a theory, but during my post mortem I noticed two grooves in the leading edge of the stock rudder that lined up with the rear of the fuse. As you commented, Eric, none of the aircraft you have been commenting on have the stock rudder. I wonder if the unsupported section of the hinge points between the rear of the fuse and the rudder are causing some kind of vibration. I never heard anything remotely like flutter, which I definitely heard when my Rev Pro came apart. My Impact had never been snapped or spun. It did have a horizontal stab failure where the aluminum tube sheared off right at the edge of the fuse. I replaced it with a carbon fiber tube. The stab landed in a swamp. Thanks to Dave Snow for donating his stock stabs.
If you are of an engineering background you tend to move into "conclusion and fix mose" pretty rapidly.
If you have a scientific background the desire for data that can be analized is immense. A bit like breathing when you have been under water too long. Irresistable but can be fatal.
I can't get into engineering-mode until I can get past the data-mode. Unfortnately a scientific approach would involve a lot of money and testing to get good data. I can relate too, and sympathise with, the engineers who want to move on and either fail or fix. I appreciate those of you who keep posting infomation.
I know, there is NO CURE!!!!
Enquiring-Eric.
quote:
ORIGINAL: BillB
Only a theory, but during my post mortem I noticed two grooves in the leading edge of the stock rudder that lined up with the rear of the fuse. As you commented, Eric, none of the aircraft you have been commenting on have the stock rudder. I wonder if the unsupported section of the hinge points between the rear of the fuse and the rudder are causing some kind of vibration. I never heard anything remotely like flutter, which I definitely heard when my Rev Pro came apart. My Impact had never been snapped or spun. It did have a horizontal stab failure where the aluminum tube sheared off right at the edge of the fuse. I replaced it with a carbon fiber tube. The stab landed in a swamp. Thanks to Dave Snow for donating his stock stabs.
Posts: 2429
Joined: 12/30/2001 From: Goodyear, AZ, USA Status: offline
So let me get this straight.
Comp ARF released a plane called Rev Pro that was really the Cocaine in Europe. It was blowing up left and right all over the country. SO they released a new model called Impact based on the same design and made some mods to it.
But this time instead of doing the work themselves they made it a kit where the pilot/builder is now at fault for the grenade action.
Seems to me they named it correctly.
BIG SMILE
I suppose that you get what you pay for. I don't like the fact that European kits are so expensive but the reality of it is that if built properly the average guy can have them stay together eh?
Posts: 517
Joined: 5/14/2004 From: Whippany, NJ, USA Status: offline
When they first released it, I remember commenting about what an unfortunate name choice they made. In retrospect, you gotta smile at how apt the name is; but it's no laughing matter to the many who have had theirs break in flight
Nevertheless, when built correctly, it's a fine flyer. I believe the one I built is still flying. Brian you out there?
One thing I discovered on Brian's broken impact was this: the rear of the fuse, just in front of the stab LE, had buckled (compression buckle) but only on one side. The other side was not affected. Once I took it apart, it was obvious that the fuse side thickenesses were not the same. I suspect their supply of urethane foam material is suffering from low QC. Couple that with hand lay-up of 2 oz glass cloth and the variables could easily stack up against you too often.
Other than that, it's a great product.
MattK
quote:
ORIGINAL: AAM
So let me get this straight.
Comp ARF released a plane called Rev Pro that was really the Cocaine in Europe. It was blowing up left and right all over the country. SO they released a new model called Impact based on the same design and made some mods to it.
But this time instead of doing the work themselves they made it a kit where the pilot/builder is now at fault for the grenade action.
Seems to me they named it correctly.
BIG SMILE
I suppose that you get what you pay for. I don't like the fact that European kits are so expensive but the reality of it is that if built properly the average guy can have them stay together eh?
Posts: 61
Joined: 7/15/2002 From: Mt. Prospect, IL, USA Status: offline
Hand lay up of 2 oz glass cloth. Not likely!! When I was poking around the break in my fuse with a eye to repairing it I stuck my fingernail right through the cloth. I thought maybe it was weak as it was right on the edge of the break so I stuck a small screwdriver into another section. I use 1/2 oz. cloth on my wings when I build my own and that is a whole lot stronger than whatever it is that Composite-ARF uses on it's fuse. It's about as strong as a rotten t-shirt. That's when I figured that it wasn't worth trying to rebuild. It would just fracture on the edge of the repair. I do agree that it is a shame. It's a great flying airplane.
Posts: 591
Joined: 3/11/2005 From: Salon, FRANCE Status: offline
Hi Did you see planes by Wistmodel named Prestige (885 E taxe included, without shipping) or by Modelltechnik-Lorenz like El-Tiburon (Abbra), Rhapsody, Cocaine. Prices of theses planes are near price of Impact, and they are very reliable. I didn't see or hear failure of theses planes. http://www.wistmodel.com.pl/ http://www.f3alorenz.de/ Regards.
Posts: 338
Joined: 2/17/2003 From: Brisbane, AUSTRALIA Status: offline
I currently have 50+ flights on my Impact without problem. I am impressed and will probably build another. Anyone who has seen my previous posts in this thread will know what extent I went to avoid the failures these models are suffering.
It is easily the best flying model I have ever owned. After a little tweaking and adjust from the intial flights I am happy to report that this model is very true with no trim or mixes. My final settings are somewhat different to their instructions.
DZ160 power is a perfect combo for this model if you plan to use IC. Electric is proven if you have deep pockets.
Make sure you make the changes as suggested in this thread. If you look at my suggestions you should be fine.
Here's a couple of pictures for those that are interested.
Peter
< Message edited by PeterP -- 3/15/2006 12:41:32 PM >
Posts: 263
Joined: 3/25/2002 From: Orange Park,
FL, USA Status: offline
quote:
ORIGINAL: MTK
When they first released it, I remember commenting about what an unfortunate name choice they made. In retrospect, you gotta smile at how apt the name is; but it's no laughing matter to the many who have had theirs break in flight
Nevertheless, when built correctly, it's a fine flyer. I believe the one I built is still flying. Brian you out there?
One thing I discovered on Brian's broken impact was this: the rear of the fuse, just in front of the stab LE, had buckled (compression buckle) but only on one side. The other side was not affected. Once I took it apart, it was obvious that the fuse side thickenesses were not the same. I suspect their supply of urethane foam material is suffering from low QC. Couple that with hand lay-up of 2 oz glass cloth and the variables could easily stack up against you too often.
Other than that, it's a great product.
MattK
quote:
ORIGINAL: AAM
So let me get this straight.
Comp ARF released a plane called Rev Pro that was really the Cocaine in Europe. It was blowing up left and right all over the country. SO they released a new model called Impact based on the same design and made some mods to it.
But this time instead of doing the work themselves they made it a kit where the pilot/builder is now at fault for the grenade action.
Seems to me they named it correctly.
BIG SMILE
I suppose that you get what you pay for. I don't like the fact that European kits are so expensive but the reality of it is that if built properly the average guy can have them stay together eh?
I'm here Matt, I lost the second Impact the end of last season, it failed right in front of the crutch I installed!! Hope you and your family are doing well and I know your enjoying the warm weather, LOL. Been flying the Majestic.
Thanks a lot for your time to inlight me about the other models.
The reason for me to select Impact is no other than this. Two friends already bought them and built them so they have experience for the construction as well trimming of the model in flight. I saw the model flying at the annual F3A contest in Greece and it really suprised me. I can tell you tha I made a test flight with the one fo the two I am telling you above. I really liked it.
Hello tmark65, I think that the El Tiburon(Abbra) from F3ALorenz or better yet the Prestige from Wistmodel are better choices than the Impact. They also have a different look (esthetically better IMHO) than your friends planes. I also read that the El Tiburon is an especially good flyer. Have a nice day Tasos
< Message edited by rcstavros -- 3/17/2006 12:45:12 PM >
Printable Version
All Forums >> RC Airplanes >> Pattern Flying >> RE: Impact 
RE: Impact - 
