Fabricating Kaplow clip retention

The Brighton needs those strong clips. Early versions of the kit had a habit of ejecting the motor mount. It was removed from the catalog for awhile until a solution was found and the kit could be retooled. From what KurtH described, it sounds like the metal retaining clips were beefed up. I just noticed that there is a small gap between the mount and the inner wall of the airframe. I can guess that might be there to provide clearance for the metal clips to be pushed away from the mount in order to remove it. Does the difficulty in moving the clips out of the way have to do with not being able to spread them far enough apart to make extracting the mount easier, or is it because the clips are very stiff and difficult to bend out? You can easily fashion a "third hand" clip spreader out of some spare coat hanger wire that will give you a hands-free way to keep the hooks spread outward while you extract or install the mount. See the attachment for a basic idea of what I am talking about.

You would squeeze the two arms together slightly and hook the prongs on the ends inside of the clips. When you release them, the arms will spring back, spreading the clips apart in the process. You will have to tweak the dimensions and the shape a little bit to insure that it spreads the clips apart far enough without causing them to dig into the airframe wall.

One possible issue would be if the coat hanger wire was so thick that the prongs would get in the way of the mount even when they are spreading the clips apart. If that turns out to be the case, you could tie a couple of small loops of thin wire or Kevlar cord to the prongs and hook them around the clips, instead of inserting the prongs themselves. The prongs would be on the outside of the clips, with little loops attached to them that hook around the clips so that when the device's arms are released, they pull the clips outward. Either way, you could probably create such a spreader in about 15 minutes out of stiff coat hanger wire.

.

View attachment Wire clip spreader.pdf

Does anyone have an exact measurement of how far CTI cases stick out past the end of the motor mount tube? I've got 3 sitting in a box in my closet, but I don't want to open the tubes till I get to the launch site.



More photos here: https://sites.google.com/site/uvmroc/home/rockets/oops-2/construction

I've got those exact same mirror hooks Stymye uses, and now am just trying to figure out how to make them work with so much overhang. I'll probably buy some aluminum spacers at my local lumber store (the ACE here SUCKS!)

Lentamental said:

Does anyone have an exact measurement of how far CTI cases stick out past the end of the motor mount tube? I've got 3 sitting in a box in my closet, but I don't want to open the tubes till I get to the launch site.

Click to expand...

https://www.pro38.com/drawings.php

Nice looking build, by the way.

For Lentamental:

Look familiar?

QQUAKE2K and I burned some motors here today. Testing the motor retention systems, of course.

MarkII said:

T Does the difficulty in moving the clips out of the way have to do with not being able to spread them far enough apart to make extracting the mount easier, or is it because the clips are very stiff and difficult to bend out?
.

Click to expand...

Yes that is the problem, I just do not have enough hands to keep the hooks spread and wrestle the mount out. I like your spreader idea, I will give it a try. If that does not work I now have a mountain of info to use to make clips

I am tempted to glue in the 29 mm mount but I really like the idea of swapping the mounts out for varying field size, and weather.

Thanks for the suggestions!

o1d_dude said:

Look familiar?

Click to expand...

Yep, I could recognize that tree anywhere!



https://www.flickr.com/photos/jameslent/sets/72157625690636857/

qquake2k said:

I make my own out of brass.

Click to expand...

If you don't have a drill press,can you use a hand drill to make the holes in the brass?I bought some brass strips yesterday at the hardware store and want to make my own retainer clips.Looks easy but don't want the drill to slip and slide around.

cjp said:

If you don't have a drill press,can you use a hand drill to make the holes in the brass?I bought some brass strips yesterday at the hardware store and want to make my own retainer clips.Looks easy but don't want the drill to slip and slide around.

Click to expand...

You should be able to drill them without a drill press. Brass drills very easily. Just mark where you need to drill with a center punch so the bit doesn't wander. And you'll need to hold the brass in a vise or with pliers so it doesn't spin out of your hand if the bit catches.

qquake2k said:

You should be able to drill them without a drill press. Brass drills very easily. Just mark where you need to drill with a center punch so the bit doesn't wander. And you'll need to hold the brass in a vise or with pliers so it doesn't spin out of your hand if the bit catches.

Click to expand...

Thanks,Will do.cjp.

Oh well ... I have to do something now, I flew the brighton on 3X D12-5 (awesome flight btw) and it blew out the motor mount, and broke one of the hooks.

I think I damaged one of the hooks, so the part where it bends became work-hardened and brittle. It is not Semrocs fault at all. I am half tempted to glue in the 29 MM , but I like the idea of good sized clusters, 3 Ds or 4 Cs are really fun.

I use midget one hole straps from the conduit section at Home Depot. 50 of them for $2.50 , bend to fit.

Thanks for the tip.

I've printed the image out as big box hired help sometimes responds best to pictures and will pay a visit to the Home Despot.

terryg said:

I use midget one hole straps from the conduit section at Home Depot. 50 of them for $2.50 , bend to fit.

Click to expand...

They can also be trimmed with a tin snips.

Ended up using Hole Seamless Eye #3 from Home Depot. Cut to length, sharp edges filed smooth and bent into shape for my L1. I was in a bit of a pinch and just wandered in HD looking for something that would work.

Worked out OK. Nice thing was that there were no holes to drill.

qquake2's post were most helpful.

Will look at the pipe conduit clamps.

In Modern High Power Rocketry 2 there is a photo of a motor retained by a flat corner brace bolted across the aft end, with the nozzle in the crook of the "L." It wasn't pretty, but it looks like it worked!

Here is what I have come up with.

I seem to have misplaced my dremel cut off wheels but I did manage to cut the brass with a worn down cut off wheel. I will obviously trim the brass further, but I need to get some cut off wheels when lowes opens at 7 am.

That is a slot cut into the motor mount and the "L" protrudes a little more than a quarter inch in to the slot. this will work for all three motor mounts.

My question is ... should I do two or should 1 hold?

Thanks

Kaplow Klip diagram from my book...

Bone Daddy said:

Ended up using Hole Seamless Eye #3 from Home Depot. Cut to length, sharp edges filed smooth and bent into shape for my L1. I was in a bit of a pinch and just wandered in HD looking for something that would work.

Worked out OK. Nice thing was that there were no holes to drill.

qquake2's post were most helpful.

Will look at the pipe conduit clamps.

Click to expand...

Was your L1 successful?

Ok, so Call it the Kurt clip ... Hopefully this will hold the motor mounts in.