Old style shock cord and mount on LOC Expediter - problem?

[billdz]

I just finished building an LOC Expediter purchased from HobbyLinc. It went together easily and I'm excited to fly it. BUT ... after finishing it I started seeing some negative reviews about the shock cord (flat nylon elastic) and the shock cord mount (epoxied to inside of airframe). For example:

"Note: install an eye-bolt to the motor mount to attach the shock cord. Whatever you do, DO NOT USE THE STOCK Shock Cord MOUNT, IT WILL RIP OUT OF THE ROCKET CAUSING IT TO GO SPLAT on the hard surface which is not funny." https://archive.rocketreviews.com/reviews/all/loc_expediter.shtml

Then I see on the LOC website that the Expediter "Now includes 5/8" Tubular Nylon Shock Cord and Eyebolt Mount", so apparently LOC agreed that the original system was inadequate. Looks like I got the old version.

It's too late to install an eye bolt, the motor mount is already glued in. How serious is the problem with the original system? Is there anything I can do at this point to fix or reinforce it?

 

[billdz]

Just got off the phone with LOC, they kindly offered to send me the tubular shock cord, eyebolt, and a centering ring on which to mount the eyebolt.

 

[qquake2k]

If you've already got the motor mount installed, how are you going to install another centering ring with eyebolt?

 

[billdz]

Good question. The tube is 4" wide so maybe I can get the new centering ring quite far down into the tube and epoxy it low enough so it won't interfere with the chute and shock cord. If that's not possible, at least I'll have the upgraded shock cord. Although the reviewer quoted above indicated the problem was the mount, not the cord itself. The old mount is a length of braided nylon cord with a loop on one end. The other end is attached to the inside of the airframe with multiple layers of epoxy. The reviewer said it ripped out of the rocket, not sure if he meant that the cord broke free from the epoxy layer or what.

 

[smugglervt]

If you haven't' already epoxied the shock cord to the airframe, I'd epoxy the CR and eyebolt as far down as I could reach (like a parachute shelf). I think it would be strong enough a recovery anchor as long as your shock cord has sufficient length.

 

[madmax]

To answer your question. No, it is not a problem. LOC's been in business close to 30 years so I'm sure if there were major issues they would have been resolved. One thing to remember when reading online reviews is not to take what's written as absolute. There are probably other reasons their mount ripped out of the rocket but they either chose not to disclose them or were unaware. How closely did they follow the directions? I have a hard time believing the mount ripped out if it was assembled and installed correctly. I've used the mount as have hundreds of other fliers I'm sure without issue. My problem when using it with the stock included elastic is the bounceback from the nosecone caving in the tube causing me to trim it down and eventually it was trimmed so far that the nose one interfered with the shock cord mount. Then I had to remove and get creative.

My advice is to use it if you followed the directions and liberally covered that thing. Just don't use elastic! Use the tubular nylon and tie it to the loop and you should be good to go.

 

[soopirV]

To answer your question. No, it is not a problem. LOC's been in business close to 30 years so I'm sure if there were major issues they would have been resolved. One thing to remember when reading online reviews is not to take what's written as absolute. There are probably other reasons their mount ripped out of the rocket but they either chose not to disclose them or were unaware. How closely did they follow the directions? I have a hard time believing the mount ripped out if it was assembled and installed correctly. I've used the mount as have hundreds of other fliers I'm sure without issue. My problem when using it with the stock included elastic is the bounceback from the nosecone caving in the tube causing me to trim it down and eventually it was trimmed so far that the nose one interfered with the shock cord mount. Then I had to remove and get creative.

My advice is to use it if you followed the directions and liberally covered that thing. Just don't use elastic! Use the tubular nylon and tie it to the loop and you should be good to go.

Happened to me too- the nose put a nice dent/crack in the lower tube of my Norad Pro Max.

 

[billdz]

@madmax - Yes, reviews can be misleading, but I got concerned when I saw that LOC had changed it, that seemed to indicate there was indeed a problem. But you're right, how can the mount rip off if secured by 4 layers of epoxy? Maybe I'll try it as is, as getting that CR epoxied in place deep down the down would not be an easy job, and would add weight.

 

[fyrwrxz]

I have several old LOC birds and the problem is not so much the mount as the elastic cord- old school hangover from the smaller birds Estes and the like made. Elastic gets brittle over time and it stretches out-losing that shock absorbsion. Add several feet of kevlar (or nylon) to slow the bird down before the shock of opening. You can z-fold it and the tape or rubber bands will absorb that much more of the shock of the parachute filling open. Time your delays to prevent premature (at speed) deployments or late (after apogee) as the bird gains speed while still streamlined. The old red epoxy they used was much like JB weld being extremely hard and would load up a Dremel sanding drum pretty fast. Straight smoke and good chutes!

 

[jd2cylman]

I used the stock idea on my LOC IV years ago. Just make sure your epoxy pool is thick enough to cover the knots in the cord. I've had some ill timed deployments on my LOC IV and the shock cord mount is still fine. The nose cone is a bit beat up... My LOC IV is an early one that came originally with the 29mm mmt. I envy yous guys that have the later ones with 38mm mmts. Oh well... I'm too cheap to buy another one since this one is still in great shape. I'm in the process of trying to change my motor retention in it currently. It was built early in my BAR comeback and I used a AeroTech motor hook. I was never gonna fly anything bigger than the 29/40-120, right? :eyeroll: Maybe I do need a new LOV IV....

 

[qquake2k]

If one LOC IV is good, two are better!