Kosdon 29mm hardware

Hi,

I have noticed that the Kosdon 29mm reloads seems to be very well priced. However, that does seem to come with some caveats. One being the motor retention. All of my rockets, so far, have been built with Aeropac retainers. I've read on a couple of sites that the Kosdon thrust rings are larger than "normal".

Before I buy any of this hardware and reloads, I was wondering if someone could chime in.

Thanks,
W

With the exception of the 76mm line, genuine "Frank" hardware comes with no external thrust ring, so it's mildly to very incompatible with AeroPack retainers as-is. I've had some of my cases grooved on the OD for an external retainer ring; as long as you're careful about placement, the 38s, 54s and 76s that I've done this way (and added the appropriate spiral snap ring from McMaster or Smalley) work nicely with the AeroPack system. They will not, however, fit inside of a Slimline without some modification.

Thanks for the information. So, for the 'Frank' 29mm hardware, one would need some kind of forward thrust ring (without any mods to the motor hardware). Is that correct?

W

Would a masking tape thrust ring word for them?

english_1969 said:

Thanks for the information. So, for the 'Frank' 29mm hardware, one would need some kind of forward thrust ring (without any mods to the motor hardware). Is that correct?

Click to expand...

Yep. The other alternative is to use a Kosdon Thrust Ring™ of masking tape; a single width of 1/2" or 3/4" will suffice. For larger motors, more wraps work well... (look at the base of the rocket on this cover!) Just be sure to degrease the case (acetone, alcohol, lighter fluid, etc.) after assembly so that the tape sticks.

I have used high temp foil tape with good results.

Now, I just have a stainless hose clamp on them, works great.

The only reason I have not modified my own cases by cutting a groove for an external snap ring is for potential 'case modification certification' yarns and dealing with that at a launch site....

A shaft collar may work.

McMaster has them...

https://www.mcmaster.com/param/asp/psearch.asp?FAM=shaftcollars&FT_158=218315&FT_858=34122&session=shaftcollars;158=218315;858=34122


JD

Masking tape as a thrust ring? I can understand that on a small 29mm motor, but on something as large as the rocket in that picture... Seriously?

I often use a hose clamp for motor retention which would hold a Kosdon motor's thrust too. That is an advantage of the hose clamp retention. It also holds the motor to the motor tube which is stronger than say clips that screw into the centering ring which is weak.

english_1969 said:

Hi,

I have noticed that the Kosdon 29mm reloads seems to be very well priced. However, that does seem to come with some caveats. One being the motor retention. All of my rockets, so far, have been built with Aeropac retainers. I've read on a couple of sites that the Kosdon thrust rings are larger than "normal".

Before I buy any of this hardware and reloads, I was wondering if someone could chime in.

Thanks,
W

Click to expand...

Kosdon Mods

karlbaum said:

I often use a hose clamp for motor retention which would hold a Kosdon motor's thrust too. That is an advantage of the hose clamp retention. It also holds the motor to the motor tube which is stronger than say clips that screw into the centering ring which is weak.

Click to expand...

The hose clamp goes over the motor mount tube and compresses it against the motor casing? Doesn't this require the motor mount tube to extend a fair bit beyond the centering ring?

That's a very clever idea to combine thrust and retention with one simple device. What size motors (diameter and average thrust) have you used this technique with?

rocketsaway said:

Kosdon Mods

Click to expand...

Had all of mine done at True-Core, Top notch work!:wink:

oops, forgot I had one more.

Gnomad said:

The hose clamp goes over the motor mount tube and compresses it against the motor casing? Doesn't this require the motor mount tube to extend a fair bit beyond the centering ring?

That's a very clever idea to combine thrust and retention with one simple device. What size motors (diameter and average thrust) have you used this technique with?

Click to expand...

was just about to ask this very question .

have used hose clamps as thrustrings on MANY kosdon motors, but never as motor retention.

Have lost one casing when using clips which bent open at ( late) ejection... so interested in a simple solution.

~ AL

Gnomad said:

Masking tape as a thrust ring? I can understand that on a small 29mm motor, but on something as large as the rocket in that picture... Seriously?

Click to expand...

not sure if that is a tape thrustring, but knowing Frank....

personally, I have used masking tape thrust rings on motors up through L class, that used to be all anyone did, I have seen M motors flown with 2" masking tape thrustrings, so it works.....

~ AL

1" masking tape on a K1050 "back in the day." It works. That's all you ever used on the old single use motors.

I've used electric tape, and I know Ed at rocketsaway.com can add thrust rings

daveyfire said:

Yep. The other alternative is to use a Kosdon Thrust Ring™ of masking tape; a single width of 1/2" or 3/4" will suffice. For larger motors, more wraps work well... (look at the base of the rocket on this cover!) Just be sure to degrease the case (acetone, alcohol, lighter fluid, etc.) after assembly so that the tape sticks.

Click to expand...

Rikki Rockett! that cover rocket is made from base drum shells. Something like 24 inches in diameter. pretty sweet.



Braden

BTW, for those who have not made the connection...

https://www.youtube.com/watch?v=i7pe2qxjjlU

Yeah.... He was also featured on an episode of " Inside Space" which was on the Sci-Fi channel hosted by Geoff Fox.

Does any one have a descent recording of it?
It was broadcast back in the 90's long before most DVR's...

All I can find is references to it on Geoff Foxes web page...
No video at all!




JD

Gnomad said:

BTW, for those who have not made the connection...

https://www.youtube.com/watch?v=i7pe2qxjjlU

Click to expand...

JDcluster said:

Yeah.... He was also featured on an episode of " Inside Space" which was on the Sci-Fi channel hosted by Geoff Fox.

Does any one have a descent recording of it?
It was broadcast back in the 90's long before most DVR's...

All I can find is references to it on Geoff Foxes web page...
No video at all!




JD

Click to expand...

I should have a good VHS copy of that, let me dig around a bit, maybe I can burn a copy..

~ AL

Gnomad said:

The hose clamp goes over the motor mount tube and compresses it against the motor casing? Doesn't this require the motor mount tube to extend a fair bit beyond the centering ring?

That's a very clever idea to combine thrust and retention with one simple device. What size motors (diameter and average thrust) have you used this technique with?

Click to expand...

You are right that you have to extend the motor mount aft about 5/8 inches. But, you have to do that with glue on retainers like aeropack too. I have also discovered that you should cut a slot in the motor mount to allow the clamp to tighten more. I have not used it as a thrust ring but use it all the time for motor retention up to 75mm.

Gnomad said:

BTW, for those who have not made the connection...

https://www.youtube.com/watch?v=i7pe2qxjjlU

Click to expand...

An interesting follow up to this story.I recently came in contact with Rikki. Turns out he's still very interested in the hobby, maybe it's time for a comeback!


Braden

Do the new motors have a built in thrust ring?

Agent Titan said:

Do the new motors have a built in thrust ring?

Click to expand...

No, they don't. However, Ed Romani at trucore can add them, I think they are only $2 per ring, plus the shipping cost. Drop it in a small section of motor tube and plug the ends, it'll ship for $1.50.

I don't think adding the thrust ring is modifying it enough to make it unsafe for a commercial launch.


Braden

I know. I'm fine with the masking tape, but just heard that the "old ones don't have a thrust ring," so I was wondering if the new ones do.

UPscaler said:

No, they don't. However, Ed Romani at trucore can add them, I think they are only $2 per ring, plus the shipping cost. Drop it in a small section of motor tube and plug the ends, it'll ship for $1.50.

I don't think adding the thrust ring is modifying it enough to make it unsafe for a commercial launch.

Click to expand...

If he's adding a snap ring groove to the case, indeed it is a motor modification, and the motor is no longer certified.

-Kevin

That's funny, my 29mm x 310 hardware had a thrust ring. I bout it directly from Paul about 15 years ago.


JD