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-   -   Foam core stab/wing servo mount repair (https://www.rcuniverse.com/forum/crash-rebuild-96/11658769-foam-core-stab-wing-servo-mount-repair.html)

pro3dpilot 01-03-2019 10:12 AM

Foam core stab/wing servo mount repair
 


I need some help!! I recently made what I thought was a fair trade for a 40% Carden Extra 260 only to find out that I got screwed. This airplane was supposed to be in flyable shape which i have come to find out that it actually needs quite a bit of work. the guy i got it from recovered it to hide all the problems that he didn't want to fix. All of the servo mounting rails that were mounted in the foam surfaces have been either damaged beyond repair or ripped out completely. My question is how do i go about repairing the holes where the servos were mounted in preparation for installing new mounting hardpoints? keep in mind that a lot of foam was removed from the wings and stabs. Ill try to post pics later. Also i will need to correct servo mounting locations for this aircraft. Anyone have any plans for this aircraft laying around?

speedracerntrixie 01-03-2019 11:09 AM

When building one of these, I fabricate a balsa wood box out of 1/8” balsa with the grain running vertical. The box is usually 3”x2” but can be made larger if needed. I embed the box into the wing and stab then sand flush to the wing skin. When it comes time to do the servo mounts I cut a peice of 1/4” lite ply to the same 3”x2” and do a servo cutout in that plate. The servo cutout can be offset if required. Install the plate into the box a little proud so it can be contour sanded to match the airfoil. Last step is optional but I like to take a 5” square peice of glass cloth and scab over the servo mount.

pro3dpilot 01-03-2019 06:05 PM

Repair started.
 

Ok so what I decided to do was take my dremel with the router setup and route out the servo mounting area and build a foam plug to fill the hole. It was easier than I had thought and prepared for. I glued the plug in with gorilla glue, and clamped everything in place to dry. Once dry I will re-sheet the area and cutout a new servo mount that I am going to build by going off of pictures I seen from another member.

speedracerntrixie 01-03-2019 06:12 PM

Many ways to go with foam wings, the only one I wouldn't suggest is just sinking in a couple hardwood rails. I've seen way too many setups like that fail. Typically I like to build servo boxes into the wings and stabs prior to sheeting.

pro3dpilot 01-03-2019 06:41 PM

I plan on building some like this guy did in post # 23 on this build Carden Build


Originally Posted by speedracerntrixie (Post 12490963)
Many ways to go with foam wings, the only one I wouldn't suggest is just sinking in a couple hardwood rails. I've seen way too many setups like that fail. Typically I like to build servo boxes into the wings and stabs prior to sheeting.


speedracerntrixie 01-03-2019 06:52 PM

That does look like a good setup. Good luck with it. What power and exahust do you plan to run? The Cardens lend themselves to canister and full pipe setups really well.

pro3dpilot 01-03-2019 06:55 PM

Leaning towards a DA-150 but I’m not sure if I’ll pipe it yet or not or even what pipes to put on it. I’d like to run a 3 blade prop but I’ve heard the 3 blades don’t 3d very well.

pro3dpilot 01-03-2019 06:58 PM

It will still be awhile befor I get that far. This plane needs a lot of work. Ive still got to remove all the hinges and reinstall new ones in the correct and centered locations. I feel like I’d be way ahead if Dennis would sell me new wings and stabs for this airplane.

speedracerntrixie 01-03-2019 07:29 PM

You will loose about 10% vertical performance with a 3 blade prop and the spool up is a bit slower as well. On a 150 the Mej 29x12 three blade works well. For ease and reliability you can't beat the stock mufflers, canisters don't give any more power and full pipes can narrow your power band. For 3D flying keeping it as light as possible, mufflers and a Xoar 30x12 wood prop would work well. That 260 is a very pure flying airplane with very little control cross couple, you will really like it when you are done. I was under the impression that Dennis and Caroline had retired, maybe not. I have heard that buying replacement pieces from him if you were not the original buyer is difficult.

pro3dpilot 01-03-2019 07:48 PM

I talked to him the other day about a canopy and some other small parts but he doesn’t produce that plane anymore so I doubt he would cut me some wings and stabs. I was thinking about the da-150 with mufflers and a 30x12 carbon prop. But I may jump up to a da-170 if I can find one at a decent price.

speedracerntrixie 01-03-2019 08:01 PM

The 170 obviously is more power but also more vibration. A typical Carden without serious lightening mods hits about 38 to 40 lbs. so the 170 may be a better choice. The Pro series are a bit lighter. When it comes to CF props I really like the newer Falcon props. A buddy of mine just got an Aeroworks 260 with the 170 and full length MTW pipes and it was an impressive combo once we got the throttle curve sorted out. My last 40% was a CARF 330 with a 150 and MTW canisters, frankly there were times when I could have used more power.

pro3dpilot 01-03-2019 08:13 PM

I’ll get it all weighed up when I get the repairs done to see where it stands. I may just get it fixed, sell it and buy a jtec kit and start over


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