Converting my PML Callisto to DD: feasibility?

[Jon Craig]

I realize that PML sells a "kit" to retro-fit their "CPR3000" DD system onto any of their rockets (or any other rocket), but it's kind of ... pricey.

Has anyone else converted a Callisto (or any other PML kit) to DD? If so, what'd you do? Construction pics, tips, etc, would be appreciated.

Callisto flies HIGH, and I'd like to fly it a lot without having to worry about long recovery marches, so it seems converting to DD would be an ideal solution.

 

[sylvie369]

I think that most of us would ignore the "CPR" kit and build an altimeter bay from scratch. If it's your first bay, a 2.1" diameter kit would be a relatively difficult starting place, but it certainly can be done. I'm most of the way done with one for my Callisto, though it got put on hold while I flew over the summer.

 

[Jon Craig]

I think that most of us would ignore the "CPR" kit and build an altimeter bay from scratch. If it's your first bay, a 2.1" diameter kit would be a relatively difficult starting place, but it certainly can be done. I'm most of the way done with one for my Callisto, though it got put on hold while I flew over the summer.

It would be my first, heh.

I have a miniRRC2 on the way, with my G3 that will be my L2 project, but, I've really been thinking about converting the Callisto as I like the rocket, but its altitude potential is a problem when selecting motors, as long as it's still motor ejection deployment.

 

[Sandy H.]

From the archive:

ebay: https://www.rocketryforumarchive.com/showthread.php?t=41767

cpr dimensions: https://blastzone.com/pml/images/cpr3kretro.pdf

I might have pictures of the whole rocket, but I used the drawings (page 4) for the Callisto with CPR to decide where to split it, add the 18" tube and just built the ebay as shown in the thread above.

Good luck!

Sandy.

 

[Pantherjon]

You could get a coupler, split the tube and use the coupler as your avbay.

 

[Jon Craig]

From the archive:

ebay: https://www.rocketryforumarchive.com/showthread.php?t=41767

cpr dimensions: https://blastzone.com/pml/images/cpr3kretro.pdf

I might have pictures of the whole rocket, but I used the drawings (page 4) for the Callisto with CPR to decide where to split it, add the 18" tube and just built the ebay as shown in the thread above.

Good luck!

Sandy.

Ahhh, this is excellent info! Thanks for digging up the link - gives me hope that I can pull this off easily enough.

What are you using for charge holders? I don't see any mounted to your bulkplates like most ebays seem to have.

 

[Sandy H.]

I epoxies the red caps that come with Aerotech motors to it, but they wouldn't stay. The rocket was lost in the woods, so I never changed it, but now, I use 1/2" pvc pipe caps.

As I mention in the thread, there are better ways to do it, I think. If I were to do it again from scratch I would:

1) Use central threaded rod concept, but with #10 hardware, not 1/4".
2) Not use electrical connections etc. I would wire the e-match directly to the altimeter connections.
3) Use a commercial screw switch or similar. My home made one was OK, but not great.
4) The end caps were good for sealing.
5) Phenolic tube is good for wear.
6) Use styrene for nose cone shear pins, not nylon screws (personal preference only).
7) Screw PVC pipe caps to the end plates.

Just my thoughts on what I would change from last time. Although, if I still had the rocket, I would keep flying it as is, not re-do it.

Sandy.

 

[Jon Craig]

5) Phenolic tube is good for wear.

I'm planning to use QT, to match the rest of the rocket. Hopefully that's not a bad idea... Heh.

Just my thoughts on what I would change from last time. Although, if I still had the rocket, I would keep flying it as is, not re-do it.

Well, as I'd said in my OP... The altitude this sucker can achieve is making motor selection a pain for me as a single-deploy bird... So... She needs altered.

 

[Sandy H.]

I'm planning to use QT, to match the rest of the rocket. Hopefully that's not a bad idea... Heh.

Mine was the phenolic version. I like phenolic better than cardboard for the coupler, so far.

Well, as I'd said in my OP... The altitude this sucker can achieve is making motor selection a pain for me as a single-deploy bird... So... She needs altered.

I meant I wouldn't re-do the ebay even though I think there are better designs. I definately understand using DD for this rocket!

Sandy.

 

[Jon Craig]

Now, looking for opinions on cutting/sizing... How big would you make each section? PML's retro-fit kit states 18" but I suspect there's nothing special about that length.

 

[Bill P]

You could get a coupler, split the tube and use the coupler as your avbay.

This is the method I used for my Quasar.

 

[Bill P]

Now, looking for opinions on cutting/sizing... How big would you make each section? PML's retro-fit kit states 18" but I suspect there's nothing special about that length.

Long enough to have room for your recovery devises.

As far as cutting, I used a hose clamp to make a nice straight line around the circumference and then ran a hobby saw along the clamps edge with light shallow cuts.

 

[JDcluster]

I bought 2 of theses rockets when I was starting to tinker with electronic deployment. I scavenged parts for a scratch rocket I was building on the first one( later built a stock version with DD). The second one; I rounded the fin tips, also made it DD.

Just added another 18-20" of new tubing.
One point that might not have been brought up is; that you may want to get rid of the piston (if it's not too late already). otherwise you will have to place you apogee charge under it & have to pass the igniter leads through it.

I flew mine on an H 242 ( around 2900 ft or so) without DD & had to walk over a mile to recover it.

JD

 

[blackjack2564]

The fincan should be long enough to hold the largest motor you wish to fly ......plus the shock cord,[ drogue if you use one] ,half the coupler [av bay] with an inch or two of dead air.

The payload ...stick the coupler[ top of Av bay] in 1/2 way with a bulkplate on the end, and put in all recovery gear as would be flown leave enough room for the NC shoulder plus an inch or two of dead air. Cut off excess. Now you have an optimal rocket.

If the supplied tube is not long enough to do this, then you need an extra section.

 

[KDRaven]

when I got my Callisto,with the 38mm motor mount, I planed for DD while it was still in the package.
I cut the BT off 12" making the main body tube the lengh of the IO kit and cut the 12" length into two parts. One part to be used for the ebay and the other part to be used so I could use it to attach the nose cone to the top of the ebay. This configuration is not realy used for DD but will allow the use of pluged motors like the G339 or the G69 motors with an altimiter in the ebay.
For DD I went with a 18" length of BT on top of the ebay for the main chute and shock cord. I am using a dual piston on the bottom. the one from the kit for motor ejection with a second one on top of that one for the DD ejection. I put the charge between the pistons.(I did not want to drill the stock piston for the charge).
I also used a length of kevlar for the piston shock cord (not the nylon one in the kit).
I dont blow the nose cone off I have the upper BT seperate from the ebay with the forward piston under the nosecone. I have a screw holding the nose cone to the BT.
For my alt. I am using the perfict flight HLK45 and it has worked great for me.
I am still having fun with this rocket and have not flown it on any thing larger than a G so far and I have gotten from 700' to 1200' depending on how it was launched. 700' was arked over and not straight up.

Keith