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Old Jan 02, 2012, 12:58 AM
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And the other part.

I have "overpowered" the airframe, and on top of that it's just foam. The stock reinformcements are not one single bar, they are 3 parts, so with 3 parts there are two sections where there is no support, like the two spaces between these dashes ---

That's where the wings broke. A clean line down where one support takes over from the other. Obviously these arrows go from one wing to the other so it won't break from now on.
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Old Jan 02, 2012, 01:04 AM
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sorry if i'm spamming the thread lol. but i figure you guys appreciate the pictures
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Old Jan 02, 2012, 01:09 AM
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oh and for ventilation I use this

http://www.amazon.com/Dundas-Jafine-...5488123&sr=8-1

and this http://www.amazon.com/LED-Wholesaler...5488123&sr=8-4
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Old Jan 02, 2012, 01:24 AM
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http://www.nitroplanes.com/60a-dy893...-eretract.html

omg dude... $120. i paid $140. what a ripoff... atleast shipping was free for me. it's $30 to florida. but still those "black firday deals" weren't deals at all

GOGOGOGOGOGOGO buy those grand cruisers!
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Old Jan 02, 2012, 09:14 AM
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Originally Posted by chatch15117 View Post
And the other part.

I have "overpowered" the airframe, and on top of that it's just foam.
Just curious what this means. You can "overpower" the airframe and still never put that kind of stress on the wings, even though they are "just foam". Wings that snap off like that generally mean that one of a couple of things happened.
1. You landed too hard and the gear forced the wings to bend upward and they snapped near the fuse.
2. You used the extra power to dive at a speed that was more than ordinary and then you pulled out suddenly, forcing the wings to snap.
3. You were going max power (which exceeds the "normal" stock speed) and did a high G turn.

(1) would have happened regardless of how much power the plane had. Just trying to figure out where the weak part of the design is and whether or not a stock plane would suffer the same fate.
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Old Jan 02, 2012, 09:18 AM
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Originally Posted by xviper View Post
Just curious what this means. You can "overpower" the airframe and still never put that kind of stress on the wings, even though they are "just foam". Wings that snap off like that generally mean that one of a couple of things happened.
1. You landed too hard and the gear forced the wings to bend upward and they snapped near the fuse.
2. You used the extra power to dive at a speed that was more than ordinary and then you pulled out suddenly, forcing the wings to snap.
3. You were going max power (which exceeds the "normal" stock speed) and did a high G turn.

(1) would have happened regardless of how much power the plane had. Just trying to figure out where the weak part of the design is and whether or not a stock plane would suffer the same fate.
You are trying to figure it out too hard

It is rather simple as I have witnessed this model in flight and it is a combination of flights with wings flexing during high G maneuvers and stresses form inside the foam where there is no spars and finally that one last flight you command the model to do your everyday "Over-Powered" maneuver (it could be a simple turn) and snap!

This model came down with both wings fractured at almost the Fuse joining section and the FUSE is still intact. A very tough model to say the least.

Don't worry, it will fly with much more durability now!
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Old Jan 02, 2012, 09:20 AM
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Originally Posted by chatch15117 View Post
http://www.nitroplanes.com/60a-dy893...-eretract.html

omg dude... $120. i paid $140. what a ripoff... atleast shipping was free for me. it's $30 to florida. but still those "black firday deals" weren't deals at all

GOGOGOGOGOGOGO buy those grand cruisers!
$30 to Florida, sounds like Drop-Ship to me....
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Old Jan 02, 2012, 02:09 PM
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no they originate out of california.

https://us-dc1-order.store.yahoo.net...3V030392490385

see california? thats my grand cruiser shipment from earlier.

These arrows I got have 25 pound fracture strength.
http://www.sportsauthority.com/produ...entPage=family

i got em for $10 for 3 arrows. anyways, there are two arrows in the wing. That means there is a minimum of 40 pounds of force to break the arrows(taking 5 pounds off for tolerance). Let's say that the plane is now 2000 grams. normally it is 1200, but I am increasing it for insurance. The wing loading is m*v^2/r, where R is the radius of a turn. Let's use the worst case scenario, pulling out of a dive. That will add 1G to the turn.

2kg*(30m/s^2/r)+2kg*9.81=18*9.81

18kg is the target wing loading, and 30 meters per second is a good max speed. 65 miles per hour. the extra 2*9.81 represents force of gravity on the wings at the bottom of the loop. If I were doing horizontal loops, perpendicular to gravity we would not need that. It would be appllied to the rudder.


This yields a 11.47 meter radius loop at full speed to begin to break the wings. And I used a very heavy plane and reduced the breaking point of the arrows. It is safe to assume that I cannot break the wings without colliding with an object.

By the way, that is a 9G turn. 18kg(target loading)/2kg(mass of plane)=9 times the mass. I should have included 9.81 in there but it cancels out on both sides.
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Old Jan 02, 2012, 02:30 PM
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$120 is a steal for this thing. I'd buy another one but I'm saving up for the upcoming FMS P-38!
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Old Jan 02, 2012, 03:27 PM
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i just spent all my cash on a quadcopter lol. i would get one more and just keep it in the garage. nitroplanes should give me free shipping after the fiasco with these bad motors they sent me.
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Old Jan 02, 2012, 04:57 PM
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OH MAN it flies great! I need to mechanically trim the ailerons but other than that it was perfect. I went with counter rotating props. Make sure you tighten the counter-rotating one because it will unscrew itself if you don't. I need to find a left hand threaded shaft attachment(will machine one back at UCF... simple CNC on lathe)

NO MORE TORQUE ROLLING! I suggest EVERYONE get counter rotating props.

http://www.amainhobbies.com/product_...sher-Propeller

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXZK93

one of each. Cost $1.95 and $2.95(pusher) at LHS(grave's). I forgot the battery hatch but the battery stayed in with a rubber band around the fuse - there is velcro on the battery so it really didnt even need the rubber band.

I can now do loops(instead of corkscrews), and the roll is fixed. before it would roll left super good and not right because of the torque from the props. now it is even. i will post pictures later of it completed. I also got the LEDs soldered and plugged in.
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Old Jan 02, 2012, 05:40 PM
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Xviper

The Grand Cruiser is a wonderful plane when flown as designed. It has plenty of power and handles quite well. I've found no weak parts of the design or components - as long as you stay in the design parameters. All bets are off if you add weight via batteries or accessories, or hop-up the power systems. Then you are not flying a semi-scale model, just a platform that you launched from. Personally, I fly my models as designed with modest or no mods and find that very gratifying.

Jim
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Old Jan 02, 2012, 05:42 PM
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Xviper

The Grand Cruiser is a wonderful plane when flown as designed. It has plenty of power and handles quite well. I've found no weak parts of the design or components - as long as you stay in the design parameters. All bets are off if you add weight via batteries or accessories, or hop-up the power systems. Then you are not flying a semi-scale model, just a platform that you launched from. Personally, I fly my models as designed with modest or no mods and find that very gratifying.

Jim
+10 What Jim posted!!!!
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Old Jan 02, 2012, 05:45 PM
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[QUOTEshaft attachment(will machine one back at UCF... simple CNC on lathe)

NO MORE TORQUE ROLLING! I suggest EVERYONE get counter rotating props.


Dude, come on! This has to be the most benign electric twin on the market. Just learn to use the left stick, and I promise you that you will be a better rc pilot for it. If your having as much trouble with this model, as it seems you are, then you must have some major timing issues with your motor/ esc. You can fly this model with a 200 rpm difference, and it is barely noticeable. Again, learn to use the left stick.
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Old Jan 02, 2012, 05:48 PM
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That's the way I plan to fly mine - scale and as per design parameters. I've had the Dynam DC-3 Skybus for this past year and have had no problems with it. I fly it fairly tame and every time, it's a crowd pleaser.
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