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Old Oct 16, 2008, 12:28 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
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Damage report

Talked to Horizon. They want the wing back. No suprise there. I took pics of the damage for you to view.
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Old Oct 16, 2008, 12:51 PM
The figure "9" Specialist
aeronca's Avatar
A Barrier Island in New Jersey, USA
Joined Oct 2003
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Quote:
Originally Posted by CapMike
Talked to Horizon. They want the wing back. No suprise there. I took pics of the damage for you to view.

CapMike,

That sure looks like a mfg. or design flaw to me. That wing should not have seperated in that fashion if the tube's shear strength had been engineered/manufactured properly. I hope Horizon treats you right!

Aeronca
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Old Oct 16, 2008, 12:56 PM
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Slidell, LA, USA
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It is the spar's bending failure, not shear strength, that caused the failure. But you are correct, there must have been prior damage to the spar or a manufacturing defect.
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Old Oct 16, 2008, 12:57 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
2,732 Posts
Quote:
Originally Posted by aeronca
CapMike,

That sure looks like a mfg. or design flaw to me. That wing should not have seperated in that fashion if the tube's shear strength had been engineered/manufactured properly. I hope Horizon treats you right!

Aeronca
Thanks. I hope so too. I am sending the wing out today. Still will have to wait a week or more before I can fly it again
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Old Oct 16, 2008, 12:59 PM
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Snoopy, I mounted the Kodak in a little plywood holder I made up. It is mounted on the CG on the left side (you can see the left wing tip at the top of the photos). A Futaba 3114 servo actuates the button for photos or vids.
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Old Oct 16, 2008, 01:06 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
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Quote:
Originally Posted by woketman
It is the spar's bending failure, not shear strength, that caused the failure. But you are correct, there must have been prior damage to the spar or a manufacturing defect.
My thoughts here is that the spar should not even bend. No prior damage as this was the second flight within 5 minutes.No problems with the landing from the maiden. SoI am inclined to think maybe defect.
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Old Oct 16, 2008, 02:50 PM
Keep Flying
Swedesboro NJ
Joined May 2008
756 Posts
Quote:
Originally Posted by CapMike
The spar tube that slides into the other wing failed at its root. I will post pics in a few minutes Seemed odd that this failure would happen. Especially with CF. Calling Horizon right now.
Hey capmike,thanks for posting the pics.that is something that shoud have not happend and horizon should take care of it,its a little scary for all apprentice owners knowing that spar broke,you say it broke at the root,does that mean under the rubberbands in the dead center thats what it looks like in the pics no matter where it happened it should not have broke flairing the plane during landing,i hope its just an isolated bad spar and unfortunately you got it. HH should take care of you if is a manufacturing defect

>>>>>Wokeman>>>Snoopy, I mounted the Kodak in a little plywood holder I made up. It is mounted on the CG on the left side (you can see the left wing tip at the top of the photos). A Futaba 3114 servo actuates the button for photos or vid>>>>

Thans pretty slick wokeman i thought of putting a servo on but just was to lazy i just hit record then takoff and video everything from takoff to landing,that is great with the still setting up the servo to activate the snap ,i might try it with my wife sony she has a 7.2 meg pix,but i cannot come home if i lose it

thanks for the info Ron
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Old Oct 16, 2008, 03:30 PM
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Slidell, LA, USA
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Quote:
Originally Posted by CapMike
My thoughts here is that the spar should not even bend. No prior damage as this was the second flight within 5 minutes.No problems with the landing from the maiden. SoI am inclined to think maybe defect.
Every spar bends if loaded. If it is not loaded, then you don't need it!

Carbon fiber has a VERY high tensile & compressive modulus (or stiffness), so it deflects very little when loaded. But it still deflects, it has to. There is very little shear on the center of the spar, just the differential lift on each wing when using the ailerons aggressively (rolling). The spar is primarily there to resist the bending moment near the middle of the wing that is caused by each wing lifting (the wing trying to "fold up"). I, for one, know without a doubt that the Apprentice's spar is sized appropriately. I have dove mine and pulled up VERY aggressively, even with the added load of that Kodak camera on it. So if the spar is in good shape, it can easily handle its normal environment. Yours either had a manufacturing defect or was damaged in some way prior to its failure.
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Old Oct 16, 2008, 03:32 PM
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Slidell, LA, USA
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Quote:
Originally Posted by snoopy3440
>>>>>Wokeman>>>Snoopy, I mounted the Kodak in a little plywood holder I made up. It is mounted on the CG on the left side (you can see the left wing tip at the top of the photos). A Futaba 3114 servo actuates the button for photos or vid>>>>

Thans pretty slick wokeman i thought of putting a servo on but just was to lazy i just hit record then takoff and video everything from takoff to landing,that is great with the still setting up the servo to activate the snap ,i might try it with my wife sony she has a 7.2 meg pix,but i cannot come home if i lose it

thanks for the info Ron
I am really only using the servo for taking still shots. If I set the camera to "movie mode", I turn it on with the servo before takeoff anyway cause I waana video the takeoff too!!!
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Old Oct 16, 2008, 03:42 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
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[QUOTE=woketman] There is very little shear on the center of the spar, just the differential lift on each wing when using the ailerons aggressively (rolling). The spar is primarily there to resist the bending moment near the middle of the wing that is caused by each wing lifting (the wing trying to "fold up"). QUOTE]

Guess this one couldn't resist the urge to clap its hands . On the lighter side I called again to find out about the other carnage caused by it wanting to flap its wings like a bird. I have sent in the entire package and they will look everything over. Hope that a replacement will be in within a week.
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Old Oct 17, 2008, 06:22 PM
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Is there any reason a second carbon fiber rod couldn't be inserted into the wings as a redundancy for such a critical part? I also read a thread where the plastic cap hooks on the rods that hold the rubber bands to fasten the wing had come loose and the wing came off in flight. I think Horizon has addressed this, but another example of a critical component that could have a backup (another dowel thru the fuse, perhaps sticking out a little further). You wouldn't want to carry this to the extreme, but some care for single-point catastrophic failure modes is worth considering.
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Old Oct 17, 2008, 07:42 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
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Quote:
Originally Posted by Sir Krashalot
Is there any reason a second carbon fiber rod couldn't be inserted into the wings as a redundancy for such a critical part? I also read a thread where the plastic cap hooks on the rods that hold the rubber bands to fasten the wing had come loose and the wing came off in flight. I think Horizon has addressed this, but another example of a critical component that could have a backup (another dowel thru the fuse, perhaps sticking out a little further). You wouldn't want to carry this to the extreme, but some care for single-point catastrophic failure modes is worth considering.
Krash if you had the wing in your hands you would see that the spar is inserted into another tube and epoxiesd in. this then slides into another tube in the other wing half.
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Old Oct 17, 2008, 08:33 PM
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Slidell, LA, USA
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Quote:
Originally Posted by Sir Krashalot
Is there any reason a second carbon fiber rod couldn't be inserted into the wings as a redundancy for such a critical part? I also read a thread where the plastic cap hooks on the rods that hold the rubber bands to fasten the wing had come loose and the wing came off in flight. I think Horizon has addressed this, but another example of a critical component that could have a backup (another dowel thru the fuse, perhaps sticking out a little further). You wouldn't want to carry this to the extreme, but some care for single-point catastrophic failure modes is worth considering.
A second spar is possible, but it would take a LOT of effort. Besides, it is entirely unwarranted. The stock design is perfectly adequate, as long as the spar and the spar's receiver are un-damaged as designed.

I have one of the kits from the first batch. I have checked and the little wing dowel end caps are on there pretty good. I guess a few were not, but mine is fine. No need for redundant wing dowels, you just have to verify that yours are in good shape.

One thing I would like to see changed is that amount of area available on the dowel caps. They should have made them a bit wider (with the dowels sticking out a bit more). As they are, you can't put many more rubber bands on there than they give you. I always use more for security. Just don't crash!!!
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Old Oct 17, 2008, 08:36 PM
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Quote:
Originally Posted by CapMike
Krash if you had the wing in your hands you would see that the spar is inserted into another tube and epoxiesd in. this then slides into another tube in the other wing half.
Yeah I actually looked at it. Looks like a second asy could be put in adjacent to it...just a thought...would require i good guide to ream holes in both wings that match up...could be more work than it's worth...but loosing your wing in flight is kinda scary!
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Old Oct 17, 2008, 08:47 PM
Airplane crasher
CapMike's Avatar
USA, CT, Shelton
Joined Jan 2008
2,732 Posts
Quote:
Originally Posted by Sir Krashalot
Yeah I actually looked at it. Looks like a second asy could be put in adjacent to it...just a thought...would require i good guide to ream holes in both wings that match up...could be more work than it's worth...but loosing your wing in flight is kinda scary!
Ah you are thinking of adding a second spar a little aft perhaps? I really dont think it is needed. I think that the design is good and the bands should keep everything together. You can bet I will be adding packing tape to both the top and bottom when the new one comes. I think that Horrizon will be taking a close look at this and come up with a fix
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