Notices
Carden Aircraft Post threads here related to the Carden Aircraft line

Extra 300 Prototype #2

Old 12-24-2006, 08:10 AM
  #51  
My Feedback: (2)
 
RickP's Avatar
 
Join Date: Jan 2002
Location: Levittown, NY
Posts: 2,012
Received 8 Likes on 6 Posts
Default RE: Extra 300 Prototype #2

I know you've been working on this, whats the latest?
RP
Old 12-25-2006, 08:04 AM
  #52  
Senior Member
Thread Starter
My Feedback: (17)
 
RobT's Avatar
 
Join Date: Sep 2003
Location: Syosset, NY
Posts: 695
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

I thought I took photo's last week...but can't seem to find them. Set the stab incidence...

With the wings set at zero...Screw down the L brackets onto the stabs. Slide the stabs onto the tube and up against the fuse. Angle Finder onto the first stab. Position the first stab to zero degrees and lock it into place by gluing some scrap blocks to the side of the fuse.

When this is locked into position trace the outline of the L bracket with an exacto. Slide the stab away and relive the 1/8 balsa fuse sides at the location of the L bracket.

After the side is relieved The stab can be replaced to the same position due to the balsa blocks. check to make sure the stab is still at 0 degrees. Drill through the L bracket and into the 1/4" ply for the 6-32 screw, again remove stab and open the fuse hole to accept a T-nut. last check to make sure the stab is still at zero. Repeat for other side.
Old 12-25-2006, 08:12 AM
  #53  
Senior Member
Thread Starter
My Feedback: (17)
 
RobT's Avatar
 
Join Date: Sep 2003
Location: Syosset, NY
Posts: 695
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

Due to internet rumors, I decided to back up the L Bracket with some 1/4" dowel. So after both stab incidences were set one was removed and a hole was drilled through both fuse sides parallel to the stab tube at location of the 1/4" ply and the stab. By using the 1/4 ply which is already in the fuse I didn't have to add any extra wood.
Attached Thumbnails Click image for larger version

Name:	Fd92746.jpg
Views:	23
Size:	40.4 KB
ID:	583343   Click image for larger version

Name:	Id95102.jpg
Views:	18
Size:	36.5 KB
ID:	583344   Click image for larger version

Name:	Hm24425.jpg
Views:	16
Size:	37.6 KB
ID:	583345   Click image for larger version

Name:	Au56041.jpg
Views:	17
Size:	38.4 KB
ID:	583346  
Old 12-25-2006, 10:04 AM
  #54  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2


ORIGINAL: RobT

Due to internet rumors,
Rob,

No rumors. I personally saw three broken L brackets last year.
2 planes wiped out. One was fixable.

Your Anti rotation pin will help.
Old 12-25-2006, 10:04 AM
  #55  
Senior Member
Thread Starter
My Feedback: (17)
 
RobT's Avatar
 
Join Date: Sep 2003
Location: Syosset, NY
Posts: 695
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

Installing the retainer screw hard points...
Attached Thumbnails Click image for larger version

Name:	Gd93825.jpg
Views:	15
Size:	58.4 KB
ID:	583362   Click image for larger version

Name:	Qm36069.jpg
Views:	18
Size:	43.1 KB
ID:	583363  
Old 12-25-2006, 10:11 AM
  #56  
Senior Member
Thread Starter
My Feedback: (17)
 
RobT's Avatar
 
Join Date: Sep 2003
Location: Syosset, NY
Posts: 695
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

Wayne,

Thanks for the heads up. I have seen many Carden's have long lives without any mods. I wonder what caused the failures...Is it possible the L Brackets in question were experiencing additional twisting / flexing forces due to something in their particular setups?

None the less that is why I took the insurance and piece of mind by adding the dowel. And by using the hard point that was already in the fuse their was minimal weight gain.
Old 12-25-2006, 02:02 PM
  #57  
paf
Member
My Feedback: (1)
 
Join Date: Nov 2002
Location: New York, NY
Posts: 79
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

I had one bracket start cracking on my Cap years ago. It was due to slight mis-alignment of the surfaces. The bolts were slightly stretching the plastic. It also seems that the stab tube always has a little play in it and the stabs can move up/down slightly. This movement gets transfered to the L bracket as well, so over time, it could weaken it enough to fail.

Wayne - the first hand failures you know about - did the owners inspect the brackets regularly, or did they leave their stabs on all the time and maybe overlooked a developing crack ?

P.
Old 12-25-2006, 03:10 PM
  #58  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

Paul,

Two were on planes that had the stabs removed all the time.
Both of those planes had one season on them.

The other plane I am not sure if the stabs came off or not.
I am pretty sure they did as he doesnt have a trailer.
Old 12-25-2006, 05:49 PM
  #59  
Senior Member
My Feedback: (3)
 
Join Date: Dec 2002
Location: Ashland, VA
Posts: 840
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

Hey fellas for a little more insurance. Install a dowel in the ends of the stab tube. Drill and tap this for a longer retetion bolt. I have a 8/32 bolt in my 35 cent Cap. When the bolt is tightened down the stab can not move away from the fus. Even if the plastic bracket breaks the extra antirotation dowel will stay connected.

FWB
Old 12-25-2006, 06:21 PM
  #60  
My Feedback: (9)
 
Join Date: May 2002
Location: Findlay, OH
Posts: 593
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

I think an extra dowel in the stabs is all that's really needed to solve any questions over whether the plastic L brackets will hold up. Aeroworks setup their older kits with a AR pin and a bolt through the ends of the tube only and those seemed to hold up fine...I've seen several with many many seasons on them with no problems.

We trust the wings to a simple AR pin and a couple small bolts to hold them to the fuse...no reason it won't work just as well on the stabs.

With a bolt in the tubes, a dowel in the root, and root tabs or L-bracket....there are no structural worries if built correctly.
Old 12-25-2006, 06:23 PM
  #61  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

I am not trying to dispute any theory put on here but, one of the planes I witnessed had a dowell in the stab tube and also had an anti-rotation pin in the stab root.
Once the L bracket broke the LE of the stab rotated up 90 degrees ripping out the anti rotation pin and the bolt in the stab tube.

This is what we came up with on my Carden's to do away with the L brackett alltogether.



Attached Thumbnails Click image for larger version

Name:	Nk28188.jpg
Views:	17
Size:	51.5 KB
ID:	583555  
Old 12-25-2006, 06:25 PM
  #62  
Senior Member
My Feedback: (3)
 
Join Date: Dec 2002
Location: Ashland, VA
Posts: 840
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

hows that a lot better ? The ply is only glued to foam. Have seen ARFs come loose here.

FWB
Old 12-25-2006, 06:25 PM
  #63  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2


ORIGINAL: jmiracle

there are no structural worries if built correctly.
These planes I witnessed were all built by preffered Carden Builders.
(It can happen)
Old 12-25-2006, 06:30 PM
  #64  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

The ply is glued to the foam root and is also encapsulated by the sheeting locking it in.
The anti rotation pin and the stab phenolic also lock the root rib in place.
The anti-rotation pin sticks into the foam at least an inch.

Like I said, I am not trying to dispute any theory or solution posted here. I am just stating what I have personally seen and what we did to eliminate the risk.

Watching three beautiful Cardens go in last year was enough to make me want something different.
Old 12-25-2006, 06:35 PM
  #65  
Senior Member
My Feedback: (3)
 
Join Date: Dec 2002
Location: Ashland, VA
Posts: 840
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

just a ? , no dispute. Stabs staying on is the main objective.

FWB
Old 12-25-2006, 07:52 PM
  #66  
My Feedback: (9)
 
Join Date: May 2002
Location: Findlay, OH
Posts: 593
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

no dispute here either....no doubt about what you witnessed...

the only piece that doesn't make sense in my mind is what difference a ply tabs makes vs. a plastic L bracket. The ply tabs will without doubt fail before the stock brackets if any side loads are present....but there be no side-loads on the tabs/l-brackets when everything is fully assembled......6 of one half-dozen of another as far as I can figure.

All flight loads trying to rotate the stab around the tube should be carried by the AR pin and the tube....which is what you show in your pic. The bolts in the ends of the tubes and in the ply tabs are just redundant methods of keeping the stabs from sliding off the tube. It's exactly the same way on the wings only the bolts run inside-out instead of outside-in. Walt even mentions this in the 300 build thread...enlarged the holes for the DA stubs so alignment is handled entirely by the AR pin....the studs just keep the wing from sliding off.

No big deal...I think everybody agrees the stock method needs minor improvement...


Great build-thread Rob....your 300 is looking great....can't wait to see more!
Old 12-25-2006, 08:10 PM
  #67  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2


ORIGINAL:
the only piece that doesn't make sense in my mind is what difference a ply tabs makes vs. a plastic L bracket. The ply tabs will without doubt fail before the stock brackets if any side loads are present....

The difference is that the tabs are integral to the root rib.
They set the incidence. The pin just adds to take away load from the tabs.

The L brackett is a stand alone peice that has to hold two seperate parts together.

Old 12-25-2006, 08:15 PM
  #68  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2


ORIGINAL: RobT

Wayne,

Thanks for the heads up. I have seen many Carden's have long lives without any mods.
I have also.

3 different Preferred Carden builders on these planes.
Relatively low number of flights on each etc..
You just need to see a plane go in one time with half of the L brackett on a broken fuse and the other on a broken stab to not use them IMO.


Old 12-25-2006, 08:59 PM
  #69  
paf
Member
My Feedback: (1)
 
Join Date: Nov 2002
Location: New York, NY
Posts: 79
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

ORIGINAL: wgeffon

I am not trying to dispute any theory put on here but, one of the planes I witnessed had a dowell in the stab tube and also had an anti-rotation pin in the stab root.
Once the L bracket broke the LE of the stab rotated up 90 degrees ripping out the anti rotation pin and the bolt in the stab tube.

This is what we came up with on my Carden's to do away with the L brackett alltogether.




I presume there was a screw in the stab tube as well, so it couldn't simply slide out. If so, it sounds like flutter brought that one down. There's no way any regular force would break off a properly installed anti-rotation pin. However, it is quite possible for flutter to tear apart pretty much anything - L brackets, dowels, plywood plates etc. On my C-arf SX, the stab tube ripped a nice 4" hole in the fuselage side before the stabs departed due to flutter.....

In my opinion, any mod that could/would have saved at least one airplane is a worthwhile investment.
Old 12-25-2006, 09:31 PM
  #70  
Senior Member
My Feedback: (4)
 
Join Date: Dec 2001
Location: Bloomington, IL
Posts: 6,378
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

We also thought flutter initially on these crashes..
I guess it could be but none of them had stripped servos....
Old 12-25-2006, 09:51 PM
  #71  
paf
Member
My Feedback: (1)
 
Join Date: Nov 2002
Location: New York, NY
Posts: 79
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

So what evidence were you able to gather to support/disprove different reasons for the failure ? It would be nice to figure it out with some certainty.

A broken L bracket on it's own does not a crash make.....
Old 12-25-2006, 10:04 PM
  #72  
Senior Member
Thread Starter
My Feedback: (17)
 
RobT's Avatar
 
Join Date: Sep 2003
Location: Syosset, NY
Posts: 695
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

ORIGINAL: wgeffon

I am not trying to dispute any theory put on here but, one of the planes I witnessed had a dowell in the stab tube and also had an anti-rotation pin in the stab root.
Once the L bracket broke the LE of the stab rotated up 90 degrees ripping out the anti rotation pin and the bolt in the stab tube.

This is what we came up with on my Carden's to do away with the L brackett alltogether.



Sorry Wayne, I think You proved there was something else going on. ...Once the L Bracket broke the LE off the stab?? Sounds like the 1/4 ply block came out not a failure in the L bracket.

I also feel some people are throwing out the baby with the bath water. Using Dennis's method for mounting the stab you gain two things:

1) setting the incidence is very easy.

2) If after you are done you find you are off by a little bit you can sand the L bracket to lower the L.E. of the stab, or add a shim / glue to raise the L.E. of the stab.

I am not sorry I added the dowel, but I think I added weight more than anything. It is hard to improve upon anything Dennis has done with his kits.

That said however later I will be adding a dowel in the wing as I did with my 330. Why? This way I can slide the wing on and it is automatically aligned... plus it won't flop while I go to my field box to get my screws.


Your are right Paul...any mod that could save even one airplane is worth doing.
Old 12-25-2006, 10:05 PM
  #73  
My Feedback: (9)
 
Join Date: May 2002
Location: Findlay, OH
Posts: 593
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

determining the "why" would definitely be nice...but I suspect that will never be known....sometimes things just go bad...it happens.

....but, I do feel the same as you paf....something "else" lead up to the L-bracket failing and the AR pin ripping out. Under normal conditions, each on it's own is capable of supporting the stab. Even IF the bracket managed to break on its own in flight...the AR pin should have held the stab in place as long as there was a bolt in the stab tube to prevent the stabs from sliding off.

regardless...on with the build!! I'm anxious to see one of these 300's finished!!
Old 12-25-2006, 10:09 PM
  #74  
Senior Member
My Feedback: (1)
 
Join Date: Dec 2002
Location: MT Pocono, PA
Posts: 1,155
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

A broken L bracket on its own can and will cause a crash. The minute the L bracket brakes flutter takes over and the rest is history.

Albert
ORIGINAL: paf

So what evidence were you able to gather to support/disprove different reasons for the failure ? It would be nice to figure it out with some certainty.

A broken L bracket on it's own does not a crash make.....
Old 12-26-2006, 12:14 AM
  #75  
paf
Member
My Feedback: (1)
 
Join Date: Nov 2002
Location: New York, NY
Posts: 79
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Extra 300 Prototype #2

ORIGINAL: as722

A broken L bracket on its own can and will cause a crash. The minute the L bracket brakes flutter takes over and the rest is history.

Albert
ORIGINAL: paf

So what evidence were you able to gather to support/disprove different reasons for the failure ? It would be nice to figure it out with some certainty.

A broken L bracket on it's own does not a crash make.....
I was referring to the setup with a screw through the stab tube, dowel pin and the L bracket.....

The best thing would be a detailed carnage pics. Things usually don't "just happen". There's always some cause, but it might be very unusual and impossible to find. Otherwise it's called a miracle

Good luck with the build Rob. I hope you'll put it to a good use in next year IMAC season !



Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.