Peter,
I think that it is "luck of the draw". If you get a thin one you lose.

I have watched George Asteris fly three new IMPACTS with no fuselage issues. He killed one with a turkey-vulture. RIP both of them. He killed the other with the terra-firma between the runway and his empty fuel-tank, way down wind, windy day.

Now hear this! He is using a 1.60 DZ, Hyde and nose ring. None of his planes have the ladder and extra formers that I used. None of his planes have shown any signs of the well known failure. I know and respectfully accept that this brings no comfort to those who have had failures, but I can see how C-ARF don't really know what to do. No approval intended by that last comment BTW.

Regards,

Eric.

P.S. I did learn that thin CA destroys the strength of the fuselage material. Medium is OK but only use epoxy. - E.

Wow Peter, Great looking plane, you did a great job making it your own!! Wish you the best of luck and with the way you have put it together I would be suprised if it fails. Best of luck!!

Hi Eric,

What CG point did you and George settle on in the end?


Regards,

Peter

Sorry to hear of your loss BB.

The IMPACT is just too variable. From the findings I made recently on your first one, it makes no sense that CARF is just burrying his head in the sand. His raw material variability appears to be too great for pattern. He should bump the thickness up at least 50% on the urethane foam, like the folks at Piedmont are doing with their TAVS material.

BB, for what it's worth, Dave L is getting ABBRAs rigged up. The BRIO also appears like a decent choice

I will be back home over the TG holiday. Let's hook up then.

Matt

I'm in the final stages of building an Impact that was started over a year ago (other planes and priorities in the way...). I need to make some exit openings for hot air -- cooling the engine and muffler. I think about all the mods/additions from the other Impact build/post mortem threads have been included, but seeing the break in BrianB's fuselage go (what looks like) right through the cutout for the muffler stinger makes me a little nervous about whacking holes in the bottom of the fuselage. Any pictures of Impact undersides with cooling vents would be appreciated -- words of advice are always welcome, too!

Thanks,
Tom

I thought I'd say something good about the Composite-Arf Impact. I went for the all white/red version and decided to paint the trim colors with Rustoleum spray cans. I found out all whites were not created equal so I bought some Composite-Arf white touch-up paint to cover the seams. The results couldn't be any better so if you don't like their paint schemes don't worry, because you can make it look great with your own custom paint scheme.

I've been reading about the Impact failures and find it interesting. I have not had a composite pattern plane, so I'm speaking only from what I've read here.

This reminds me a little of a failure state in the Army OH-58A & C helicopters. These are versions of the Bell Jetranger. The failure mode is called critical tailboom dynamic mode. The tailboom would buckle at a certain spot during vibrations in autorotations. Basically, a terrible vibration would be introduced at the rotor head and then cause the transmission to start oscillating in the pylon mounts. The vibrations would travel down the tailboom in a sine wave. Once they reached the end of the tail boom (with vertical fin and horizontal stabilizer) the vibration wave would start a return towards the nose. This would meet the next wave from the transmission, and the buckling would occur at that spot.

I'm wondering if vibrations aren't flexing the fuselage in a similar way. They do damage. We would look for 'oil canning' on the panels to find small buckles in the sheet metal. Someone mentioned a nose ring set up doing well, without problems.

Or, maybe the tail feathers are flexing the fuselage and causing stress failures.

Hey OhD --

The paints look good. If your Impact is IC powered, could you post a photo or two of what you have done for venting cooling air around the muffler exit? or anyplace else for that matter!

Thanks,
Tom

Tom,

This is how I vent the exhaust

Adrian

Sorry, let's try this again

Adrian

Adrian --

Thanks for the shots of what you did. Having some vents in the engine cowl as well as the belly back by the muffler exit seem like a good idea. Thanks again! Is your Impact holding up well? After reading all the good things people have said about the way it flies, I can't wait for the snow to melt and the temp to get flyable.

Thanks,
Tom

Tom,

Make sure you have enough ventilation, especially if you are using a DZ, it generates tremedous amount of heat.

I have about 60 flights on the plane now, and its holding up well, thanks to all who contributed their ideas on modification. The plane is flying well with very little mixing. However, I don't particularly like the way it snaps, still thinks the wing area is a bit on the large side.

Adrian

I do plan to use a 160 DZ -- and being aware of all the heat they can generate I wanted to get some Impact wisdom/experience from the "field" so I could get enough ventilation but not cause unecessary structural weakness. Your pictures will help a lot. I have followed the various Impact threads with great interest also and have incorporated all the items to help the fuselage maintain its integrity...

If you're "flying well with little mixing" you must have it set up pretty straight and have the CG in a good spot -- where do you balance in relation to the wing LE at the root?

You also mentioned not being impressed with the snaps -- what don't you like about them?

Thanks,
Tom

Tom,

Mine will be electric but I'm also interested in cooling exits. I looked at Jason S's but it's tough to estimate the total area of the holes from the photos. If anyone has a successful design, I'd be interested.

Jim O

CG is set per instruction with battery pack (yes, I'm still using Ni-Cad) as far forward as possible right behind the floor exhaust opening, I'm using two Futaba 9650 on the tail. Wing and stab incidence first set at zero/ zero, I ended up with very slight negative incidence. Might not be suitable for all, but that's the way I like it for both upright and inverted.

I have the following mixes, 3% on thr to down ele, 5% thr to left rudder, 2% left rudder to up ele, 1% right rudder to down ele. As for rudder to aileron mixes, 3% on one side and 2% on the other side.

I am using a condition on my elevator stick. I normally fly with very little elevator, but, when I give it full elevator, it increases aileron, but decreases rudder throw. With my Smaragd, both the snap and spin stops on a dime. But with this one, I still haven't quite master the snaps yet. Eventhough I had over 100 snaps, it stil looks real funky, guess I have to keep playng with the throws.

Composite Arf makes great planes. I have the 2.3m Extra 330L and love it. I guess they should just stay out of pattern. I was about to buy an impact when a fellow modeller showed me all of the hassles he had assembling his including the mods to "make it live". Based on his feedback, I did not buy one - sure am glad I didn't now.

Comp Arf - you need to make it right - Pattern is too small a community....

Paul