Ricmussman

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Well here is my new project. I will be building this plane for my primary ship since my last Carden decided to have catastrophic tail failure. I will be deviating from the plans in just a few areas, ie: lightened motor box, rudder servos in tail, and a stab modification, fuse hatch. I will post pics of my progress, and answer questions and take suggestions, all right here courtesy of RCU...

I took some pic for your enjoyment. All of this work has been done in the last couple of days (I have no life).

Ric

Ricmussman

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Motor Box.....

Flyin Woodbutcher

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looks a little heavy , are you keeping count of how much weight you are removing ? What happened to the tail of the other one ?

Kent

Ricmussman

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Fuse sides.... Note the servo hole for rudder servos. I will be using two servos on direct drive, but I put spaces for three just in case. Also the hard points are in place for the tail modification. I am going to make the stab root out of 1/8 in aircraft ply and build tabs (2) that will bolt right to the fuse. Also there will be anti-rotation pins installed. I will not be using the PLASTIC L-brackets on this plane. When I get the fuse finished I will begin work on this vital modification.

Ric

Ricmussman

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I fly IMAC sportsman class and in that sequence there is a inverted line across the box, I was making that pass and just before the 2 point roll both stabs departed the plane. I was not flying too fast and there was no sign or sound of flutter. One of the L-brakets was broken in half and still attached to the plane. The other side was ripped off. It is all a mystery too me. Upon departure of the tail feathers I killed the engine a put it into a spin. Believe it or not but I did fly the plane back toward the runway but some trees got in the way and broke the fall. One week later the left wing is still 120 feet up a tree and the stabs are gone???? and all I have is the damaged fuse. Amazingly I didn't break the Prop/spinner or damage the fiberglass and the remaining electronics. Kinda lucky all things considered....

Here is the link for the old plane: [link]http://www.rcuniverse.com/forum/m_4442582/tm.htm[/link]

Ric

Ricmussman

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I have no scale but here is what I have saved (Not all of the saw dust has been accounted for) from the motor box.

Flyin Woodbutcher

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Hey Ric sorry you lost the plane that was nice for sure. The mod you are doing is a good one. Although the L bracket design gives you a way to adjust the stabs for fine trimming. Anti rotation pins , I dont know why the plans dont include these. I put these on my35% Cap for security.

The only real way to keep the stabs is the bolt through the tube, I use these in all my planes. I have a dowel in the tube that is threaded for a 6x32 bolt. The bolt goes all the way in , not just the tip that the plan shows. Seen two 40% Cardens live to fly another day because they had the bolt in the tube. The first went through some pine trees and when it came out was still landable. The L brackets had ripped out of the fus , the stab tube was bent back 15 degrees on both sides but the little bolts held. The other plane tried to keep up with me in a power dive and fluttered the ass end bad. Destroyed the whole rear of the plane , both stab servos had the gears stripped. The little bolts in the tube held the left stab enough to keep the anti rotation pin in what was left of the fus. Hell of a fight to land it , I flew top cover over him so I could watch and still fly my plane.

Moral of the story, little bolt in the tube, anti rotation pin , ply plate mounting bracket and L bracket for trimming.

Kent

ps dont you just love not having a life so you can work on planes BALLS TO THE WALL ?

Flyin Woodbutcher

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One more thought , be carefull taking out to much meat of the motor box and landing gear mount. Carrying around 6 to 8 ozs extra for a season is no big deal. One day something dumb will happen and the strength of the box/mount will pay you back in saving a good day at the field. Lite aint always rite or lite weight aint what its CRACKED up tp be.

Kent

PJFaller

I have found that the L brackets work great. Here is the major problem that I have seen with the build on using the L bracket. Now speaking from experience I had both horizontal stabs blow off my 40% Extra 330, and the L brackets stayed in place and actually pulled the foam all the way through to the top of the stab. What ended up happening was I had the programming in the radio screwed up had the ATV's way down with a single servo on the stab half and I got severe flutter doing a high speed rolling pass. Airplane tumbled into the ground and was repairable and is flying today. So I have seen my own stab halfs come off.

Here's what I think happens.....Ive built several cardens and two 40% Extra's.

When guys build these things what happens is I think they do not get a 90 Degree angle between the root of the stab and the fuselage. The L bracket is the last thing I do on the airplane. I get the plate on the stab half as flush to the bottom of the stab as possible, but when I finally epoxy it in place, I but everyting up to the fuselage and set my incidence. Usually the stab plate that has the 6-32 bolt on it for the L Bracket comes out of flush just a little bit when curing so that the L bracket is at a perfect 90 degree angle to the fuse. I NEVER sand that plate flush. The reason being is that when you sand it flush and then you drive the 6-32 bolt in to attach the stab half, you pull the L bracket passed 90 degrees when you tighten it, and it always has a load on the 90 degree point. With flight loads it will eventually break. You NEVER want to have this point loaded because it will fail.

Between doing that and driving a dowel in your stab tube, you should never have a problem. By putting a ply plate on the end of the stab and bolting it in with two bolts like Aerotech does, you are putting all the stress of the stab and incidence on one point of the stab. At least Cardens way if it is done right distributes the load from the leading edge of the stab throughout the stab tube. One point of failure should not destroy the airplane. Again all this being said, if it is done right.

Just my two cents...take it for what it is worth, but when my failed, the L bracktes stayed on the fuselage and the foam pulled out...Again it was the worst flutter I have ever seen.

My other comment to the guy building this particular 40% Extra, is be very careful about putting your rudder servos in the tail. The airplane is going to be hard to balance. I have my rudder servos just aft of the motor box, all my radio and battery equipment forward, and two 8611's in the stabs and I have my batteries in the forward part of the motor box. You might have hard time balancing the airplane set-up that way. This has been the case with both of my 40% Extra's.

Good Luck and enjoy the build.

Pete

BBW Walt

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Man this build looks familiar...

Ricmussman

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It should, it is just like your 260 for Wayne.....

Thanks for the help....

wgeffon

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Thats why my new 260 and Ric's 330 have anti rotation pins in the stabs as well as the tab mounting root rib and bolts through the tube.

FWIW,

I have personally witnessed 3 Cardens lose tails this season. All had bolts in the tubes and L Bracketts.
There is no way anyone can say with any certainty what let go first or what the sequence of events was prior to the stabs leaving the fuse but in each case, there was a broken L brackett attached to the fuse when we examined the wreckage.

My descision to not use the bracketts was made after #2 went in.
Then I had the misfortune of watching Ric's go in.

I am comfortable with the changes Walt did for me.

Flyin Woodbutcher

My Feedback: (3)

I dont see how the stab can completly leave the plane if the stab tube has a bolt through, done properly. Now if the bolt is only threaded into the thin hollow tube I can see why. This will not hold at all the bolt will rattle out. My 35% Cap has a oak dowel sanded down to fit in the tube, then another piece in the stab . This has all been threaded and hardened with CA. I sure hope this all stays together.

Kent

rcplanefan

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I can tell you that on Rick's plane, the tube broke off - right at the side of the fuse. I'm sure it was violent when it happened. I think Wayne and Rick are on to something here, and it is such a simple change that there really isn't any reason no to.

Ken

wgeffon

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Kent,

Lets assume the L brackett fails (Not that we know 100% that it did) and there is no anti-rotation pin in the stab.
The plane is flying at a moderate speed and it breaks. The leading edge is going to flip up and in the process of rotating up it will rip out any attachment the stab tube has.
In two of the cases I saw this season, you could see the tube was twisted in that direction and then it snapped in half.
In Ric's case, we never found the stabs of tube to see what they looked liked.

On a side note:
The first two planes I saw this happen to this year were both built by highly respected, preferred Carden Builders. There is no question whether those planes were put together correctly.

BBW Walt

My Feedback: (11)

Probably the biggest issue I see with the Carden design is the lack of an anti rotation pin. With a correctly built in anti rotation pin and 1 stab screw through the tube you could literally forget the plastic bracket screw and I really doubt anything would happen. Wings have been held on this way for years. Pins in the root and one screw through the wing into the tube. Seen hundreds done this way. I wouldnt do it this way but the real key is the pin to carry the load and hold incidence. With the pin, if the plastic bracket failed you'd never know it till you looked at it after landing. The stab screw would not allow the stab to come off and the stabs could not rotate...Anti rotation pins are in

Flyin Woodbutcher

My Feedback: (3)

I got it now, I never thought about the twisting of the stab. Plenty of force there to snap the tube off. Now I will have to do some remodeling on a finished plane and install anti rotation pins. I'm scared of the brackets now[]. Thanks for the explination.

Kent

zzw26n

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Kent,

When you figure out away to get the anti-rotation pins in, please post your method. A few of us would be interested in how you do it.

thanks, zz

wgeffon

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No Glo can help with how he'd retrofit one.

Walt?
You there??

Flyin Woodbutcher

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My first thoughts are to use a dowel through the fusalage. I can then install brass tube recepticals in the stabs, about an inch deep. Doing it this way will be less intrusive to the perrty covering job. This can be done using a brass tube hole saw, make the hole nice and square first then install a stab. Drill through from the other side into the stab and the hole should be lined up nice. Do the same for the other side. Although the there wont be any extra reinforcement in the fusalage it should be more than strong enough to avert disaster.

Kent

wgeffon

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Kent,

That all sounds good but your really going to need something more than just the 3/32" side sheeting to hold that anti rotation pin.

Flyin Woodbutcher

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Wayne

I agree the sheeting is not strong enough to hold anti rotation pins of a normal type. By using a pin from one stab continious through the fus into the other stab I will have enough hold strenght if a bracket lets go. I may figure out a way to get a lite ply reinforcment on the inside before its all done. Opening up the rear of the fuse may weaken the fuse , in the long run.

Kent

babflyer

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Is that Kieths kit that you are building Ric? Got to hand it to you as I would be to depressed to start in on another build.

BBW Walt

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Install the stabs on the stab tube. Tack glue a piece of 3/8th sq. to hold both stabs on zero. With a soft pencil mark the outline of the stab airfoil on the fuse. Remove the stabs and draw a line through the center of the airfoil. From the leading edge come back on the center line 1 inch and drill a 1/4 inch hole using the brass tubing as a hole saw. Do both sides. Reinstall one stab half and set up to dead 0..Through the opposite side slide the brass tubing through the fuse and out the hole the stab is set to 0 on. Drill the 1/4inch hole into the stab 2 inches deep. This will set the correct angle to remove the stab with the root angle taken into account. With a 1-1/4 hole saw cut out 2 donuts from 1/4 birch ply. Epoxy these on the inside of the fuse for the anti rotation pin to set into. I shimmed the drill bit hole and installed a 3/16 drill bit in my hole saw arbor. I usually hand sand the holes in the donuts to make a perfact fit on the dowels. Very simple mod. If you want to use the plastic L brackets supplied by Carden I would make the root rib out of light ply to reinforce the hole cut in the stab. Waynes pins are 2 inches in the stab and 3/4's of an inch into the fuse..Hope this helps,Walt

Ricmussman

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Brent,

I am still bumed about the last plane, but I need a plane! So, I have no choice but to start over. I am just glad Keith was able to help me out. I have been slowly building this plane, and trying to work on my 35% Hurley, and I have the Club Raffle Plane to assemble by next week for our big fall event.

Here is my latest pics of my progress. I got the fuse body put together and the motor box installed. Note the nice truss work of F-2, F-3, F-4... I am happy about this