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Old Aug 27, 2012, 06:02 AM
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Rollo340's Avatar
Joined Jul 2011
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Try Outs

Wish you all a fantastic competition and lots of fun ...

...stay safe Senior and Mong, RJ
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Old Sep 05, 2012, 01:45 PM
usaf3kteam
rcgeorge's Avatar
Joined Sep 2005
5,711 Posts
The US Concept team is going to the worlds Mike Smith and I. Charlie will likely go with and fly the prelim contest I hope. Thanks to Roland, Mong and Eric you the best.
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Old Sep 05, 2012, 09:44 PM
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gjensen's Avatar
USA, CO, Littleton
Joined Jul 2005
733 Posts
Roland,

I flew the new wing (X2) for the entire team select contest, only changing CG as wind conditions changed. It flys every bit as good as it looks! George discovered a little delamination on the horizontal stab. It may have been from an earlier mid-air. I examined the plane, but saw nothing.

I flew with quite a bit more camber than usual and it made a huge difference for me.

Cheers,

Gary
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Old Sep 06, 2012, 01:50 AM
Armsoar test pilot
Melbourne, Australia
Joined Jun 2008
585 Posts
Hi Gary, Mike GMo, CMo,
Can you share some of the settings that worked for you at the TS?
I will help me get my Concept tuned up. It sounds like there are a few settings that really make this plane rock!
Cheers,
Marcus
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Old Sep 06, 2012, 10:31 AM
hot air rises...
jfinch's Avatar
Pleasant Grove, UT
Joined Jul 2005
7,844 Posts
I too flew my CX2 for about 1/3 of the contest. LOVE that plane! Marcus, the settings that Roland suggests are perfect although I can launch higher with just bit more reflex in the wing then suggested. Maybe 2-3 mm of reflex.
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Old Sep 08, 2012, 01:44 AM
Zeus
Wild East
Joined May 2008
291 Posts
Quote:
Originally Posted by Machineman View Post
Hi Gary, Mike GMo, CMo,
Can you share some of the settings that worked for you at the TS?
I will help me get my Concept tuned up. It sounds like there are a few settings that really make this plane rock!
Cheers,
Marcus
Marcus, for sure any very personal settings might be not exactly the perfect settings for you, since all settings depend greatly on your very personal trow / flying style and not to forget the conditions you are flying in, such as altitude, temperature, humidity and wind conditions.
The suggested settings in the CX2 manual are chosen to work under any given condition with the best margin of safety. From there you should go to optimize the plane in a number of test flights, how it works for you the best.

One of the perhaps most important settings is the proper reflex for your throw style, which is done as a DIFFERENTIAL reflex. The reasoning for that I have attached again while it might get overlooked in older posts.
The optimum negative throw (reflex) you will find right below the point where you can hear a loud hizzing noise during throw, which starts at about 3.5mm -4mm of reflex.
At this point the airflow separates from the lower flap surface, creating a strong vortex which is the sorce of the hizzing sound, equal to the drag it generates.
You will have to reduce the reflex proportional to your differential reflex setting, untill the sound disappears and your CX2 will launch silently, indicating the most efficient reflex setting, with lowest achivable drag.
To get your plane launching like on rails without the slightest sign of banking in any direction, simply adjust the amount of differential throw. The launch should look similar to the attached launch analysis.....

Along with it goest the adjustment of the mixed-in elevator trim in launch mode, which gives you the optimum climb angle of about 65 - 70, considering an horizontal swing and slightly upwards directed trow / release. In average, this trim amount is somewhere between 0 and ~0.5mm down trim.

The 2nd most important setting is the differential for ailerons....
I recommend to use an INVERTED differential to gain the flattest and most efficicient circular flight.
Here you can start with about 50% INVERTED differential and increase or decrease in smallest steps, untill you can achive the flattest ciclular flight, giving still enough effect of the ailerons for tight turns and compensating turbulences in any given condition.

For the THERMAL MODE, apply positive camber in a range of 1.5mm to max 3mm, where the airfoils will have their best lift, right before starting to generate exessive drag, if the positive camber gets too large.
A good idea might be, to have the camber on a slider adjustable in thermal mode.

Last not least, the right CG location for your conditions, which in average should be around 84mm in mixed wind conditions. In dead air conditions you might go back to ~86mm or even beyond, depending on your flight style. In more heavy wind you can move your CG arround~81mm to get best penetration without the need to install ballast at all.

If you might follow some or even all of those suggestions, you will be able to find your personal right setting pretty soon, which will make your CX2 really rock....

Roland
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Last edited by KINETIC; Sep 08, 2012 at 04:04 AM. Reason: typos
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Old Sep 08, 2012, 09:54 AM
Armsoar test pilot
Melbourne, Australia
Joined Jun 2008
585 Posts
Thanks for the great info Roland. I had not seen it before. I'll give it a go and let you know how I go.
Cheers,
Marcus
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Old Sep 14, 2012, 01:37 PM
Chuck 'Em and Chase 'Em
Fly2High's Avatar
United States, NY, Plainview
Joined Aug 2005
8,119 Posts
Anyone have any Concept pictures in flight suitable for use as a desktop?


Frank
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Old Sep 14, 2012, 02:33 PM
sewing machine thumb
United States, CA, Palo Alto
Joined Jul 2001
2,305 Posts
noise on launch

I picked up a barely-used Concept from a friend who hadn't flown his for a year. I just got the first flights on it this morning. When I throw hard it makes a very unnerving cracking sound. It sort of feels like something is moving in the tail.

I have two other Concepts that don't make a similar noise. No, I'm not tip-striking.

Any ideas?
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Old Sep 14, 2012, 02:38 PM
Chuck 'Em and Chase 'Em
Fly2High's Avatar
United States, NY, Plainview
Joined Aug 2005
8,119 Posts
Is ti possible the wing can shift on the fuse?
crack in the composite somewhere?
Crack in the fuse?
tailgroup come loose?

I would go over it with a fine tooth comb looking for cracks.

Do not know.....
good luck

Frank
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Old Sep 14, 2012, 02:47 PM
or F, J, K, or even TD
FLY F3B's Avatar
Joined Jun 2007
2,917 Posts
Check the wing hold down system for movement. that noise could just be the carbon pin slipping ever so slightly in the carbon hole. Is the crack coincident with the release? during rotation or before release? Hard to tell I know, but figuring that out will help you locate the source of the cracking sound.

Mike
PS. Try stainless steel or aluminum wing bolts. The nylon does allow a little bit of movement.
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Old Sep 14, 2012, 03:03 PM
hot air rises...
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Pleasant Grove, UT
Joined Jul 2005
7,844 Posts
I think I know the plane and have heard/felt the noise, Frank. It's been there from the very start. If you haven't already checked, make sure the battery and/or receiver are held securely in place or at least pre-pushed over to the right side of the fuse. Also make sure the canopy is taped down.

When I was throwing it I always thought it was making the noise out near the wing tip near the peg but could never find anything "wrong" in the wing... See you tomorrow!
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Old Sep 14, 2012, 06:01 PM
hass-alfed and bass-ackwards
carlsoti's Avatar
United States, AZ, Chandler
Joined Jun 2008
5,311 Posts
FWIW, a few Concept pilots I know have gotten in the habit of taping the wing to the fuse in addition to screwing them together. This is even on new planes. The little bit of room necessary to make mating the wing and fuse easy can give room for the wing to shift ever so slightly during a hard launch. You don't notice it at first, but after a few hundred throws (maybe more) the holes start to elongate, and from there, it goes downhill fast.

Aside from that, IDK. The nasty cracking sound that mine made was from throwing a plane with a busted spar, and not realizing that was the issue.
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Old Sep 14, 2012, 11:10 PM
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United States, IL, Bloomington
Joined Feb 2002
977 Posts
Quote:
Originally Posted by wgeffon View Post
Blew up a wing today....
Had been flying for a while. Caught the plane and threw again. Nothing working.
The plane hit a tree and broke the wing. Spar, D box, leading edge...
The battery plug came undone from the extension plug. Not sure how, nothing had moved and when plugged back in, everything worked fine.

Bummed.
Roland built me a replacement wing and I just received it today.
It arrived in perfect condition. Much better than the last time when FedEx damaged both new wings.
This wing fit to my existing fuse without any adjustment. That says a lot about the quality of planes you get when you purchase one from Roland.
All I had to do was solder up the female end of the wiring harness, glue it into the wing and glue in the throwing peg.
It's ready to go.
Nice to have two of these again.
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Old Sep 15, 2012, 12:55 AM
sewing machine thumb
United States, CA, Palo Alto
Joined Jul 2001
2,305 Posts
Quote:
Originally Posted by carlsoti View Post
FWIW, a few Concept pilots I know have gotten in the habit of taping the wing to the fuse in addition to screwing them together. This is even on new planes. The little bit of room necessary to make mating the wing and fuse easy can give room for the wing to shift ever so slightly during a hard launch. You don't notice it at first, but after a few hundred throws (maybe more) the holes start to elongate, and from there, it goes downhill fast.

Aside from that, IDK. The nasty cracking sound that mine made was from throwing a plane with a busted spar, and not realizing that was the issue.
Wing is taped front & back. Wing and stab screws are aluminum.

I didn't have much time to try to figure it out today. I flexed the heck out of the boom without finding anything. Peg seems solid too. I didn't get a chance to really go over the wing. Didn't even think to check the stuff in the fuse. I'm in Utah tonight for tomorrow's mini-contest, so Finch and others can have a look, too.
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