Loc Precision Caliber-ISP

So I want to build my first HPR rocket, however I’m scared to even start. My biggest issues was the inclusion of the baffle with my kit. When I lay it all out, there seems to be very little space left for the chute and shock cord. I tried packing everything into the 6 inch space and it needs to be so tight I’m worried the chute might not deploy. The entire top half of the rocket is a payload bay.... seems strange to have 16 inches of payload and only 6 for recovery.

I was thinking my options are the following, either

1. Leave out the baffle entirely.

2. Cut the baffle and pieces down to either 3 or 4 inches, giving me up to 9 inches for my recovery bay.

3. Slide the 8 inch coupler up so that 5 inches are glued in the upper tube and only 3 inches into the recovery area (seems like a bad idea, but I figured it was always an option).

4. Just put it in as I have it laid out and try to stuff it all in. I might be missing something and I’m guessing Loc Precision tested this all out when they made the kit.

Any advice?

Do you have plans to use the payload area for anything? Are you installing bulkheads in the 8 inch coupler? Do you want to be able to set it up for dual deploy later?

You could pin/rivet the 8" coupler in place, leave out any bulkheads, pop the nose cone only, and use the top section for recovery gear.

Good observations and forethought. Loc 3.0 has made some updates to this kit since I built mine in 2012. Certainly the baffle is a new addition and takes up space (if you choose to install it). Further, it appears that the motor mount tube and the coupler at the lower/upper airframe joint may be longer; both of which take up recovery space.

As you mentioned, you could certainly omit or cut down the baffle. If it were me, I'd skip the baffle and cut down the motor tube if needed...motor tubes only need to be long enough to center and support the motor. If you do choose to keep the baffle, make sure you position it such that it doesn't interfere with the longest motor you intend to fly.

I built the 3" LOC Caliber a couple of years ago. I left out the baffle. Things were just to tight with the baffle in. Last year I bought a 3" avionics bay from LOC and converted it to dual deployment. Glad I did as I was getting tired of long retreival hikes. It works great as a dual deployment bird.

Greg Furtman said:

I built the 3" LOC Caliber a couple of years ago. I left out the baffle. Things were just to tight with the baffle in. Last year I bought a 3" avionics bay from LOC and converted it to dual deployment. Glad I did as I was getting tired of long retreival hikes. It works great as a dual deployment bird.

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I like those colors, very classy looking.

I would delete the baffle and cut the motor mount tube down a few inches as well.

wow, its changed a bit..

When I built mine (2 years ago) there wasn't a baffle system. It was intended to be a standard dual deploy 54mm rocket capable of 5-8 k feet flights.

To me, the point of a baffle on an intended dual deploy rocket is kinda pointless.. and, as you've noted, takes up space. (It seems LOC didn't really think thru adding the baffle system.. They added it more for a selling point than for a purpose..)

Eric's comments are bang on.

I assume you're not certified, so you'll be needing to get certified to fly some HPR. And that means you'll likely be looking at 29 mm or 38mm motors at first. Do you have an adapter? Do you see yourself getting 54mm motors for it? Do you see yourself pushing this to the stratosphere [really high flights]? When do you plan to explore Dual Deploy? Other electronics [Tracker]?

These are some big questions to ask, and I'm sure you're "What the ...!" But don't worry, take it slow.

I'd also recommend you swap out the 54mm MMT for a 38mm MMT (Motor Mount); 12" should suffice. Get a blanket & ditch the baffle. If you don't have already, invest in a Jolly Logic Chute release. Build the AV bay, with removable bulkheads, so you can add an altimeter in the future (and then add Dual Deploy)..

Take little steps, be comfortable as you advance..

mbeels said:

I like those colors, very classy looking.

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I don't know if you enlarged the pic but the tye dye T I'm wearing has a NASA logo on it. I was at Wallops in June 2018 and I was in their gift shop. I saw this tye dye shirt with both the NASA log0 & Wallops and thought "Far Out!". So I bought it.

I built a Caliber ISP last spring and documented the build with a thread on TRF. I omitted the baffle, added an electronics bay and permanently converted to 38mm

love the rocket

have fun!

Wow guys, thanks for all the great responses. Theory, I had seen your thread, but I wanted to make sure I was not missing something regarding the overall spacing. I really can't even imagine flying a 54mm motor at this point, but I once read in a thread to always use the largest MMT that you might ever imagine using.... Sooo, I had already ordered both the 54-38mm and 54-29mm adapters. I have a feeling I'll be using adapters 99% of the time, but hey, you never know!

In response to several of the comments:

I have no plans for the payload area right now... My altimeter is a jolly logic altimeter2 and doesn't technically need the bay.

I am not level 1 certified, but I would like to do it with this rocket.

I would like to eventually set it up us as a dual deploy in the future. But then again, I would love the excuse to have to build an entirely new rocket! Greg, when you converted to dual deployment, did you have to buy a new upper tube as well? I'm half debating whether I should just buy one of those kits now and incorporate it for when the time comes.

I do have the desire to reach the stratosphere, although this rocket is already looking like the total cost into it will be 4 times that of an Estes kit (a reason not to add in the electronics bay at this time). I do not want to lose it.....at least not right now.

Regardless, based on your comments, the MMT being 17 inches is excessive. I'll shave off a few inches.
I'm going to leave out the baffle as well. Believe it or not, the kit actually included a nomex blanket. Hopefully I don't destroy the nice chute they included.
Lastly, I think it is finally time to experiment with plastic rivets. That way, I can really leave my options open with regards to what I do with the top half in the future.

Thanks guys!

Mine likes large 29mm motors and most all 38s. Really looking forward to the I300 I just purchased and small J motors. The J350 and J420 will be solid flights.

The pictures below are of an H268. Nice solid flight. Keep in mind that the finished weight with the electrics bay is a fair amount more than stock. Mine is 74oz fully loaded and ready to fly.

Theory said:

I built a Caliber ISP last spring and documented the build with a thread on TRF. I omitted the baffle, added an electronics bay and permanently converted to 38mm

love the rocket

have fun!

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I made mine 38mm too. Cheaper to fly. I don't care too much how high it goes, I love launches.

I built mine without the baffle-took way too much space. It is a great Level 2 rocket and with the adapter (I left mine 54mm) you can still fly 38mm. I also added a switchband-good way to go-LOC's is nice, blue tubes switchband kit was good but expensive. I had similar questions for this kit-if you use LOC's Nomex shock cord protector you may never zipper. I have flown I's and J's in this one. You can still get ~5000ft/600mph with a 38mm J425 in this rocket-plenty of fun and altitude without goin ultra nuts with a big K. I believe mine is 3 lbs. 4 oz. without dog barf and a motor.

MidLifeMike said:

In response to several of the comments:

I am not level 1 certified, but I would like to do it with this rocket.

I would like to eventually set it up us as a dual deploy in the future. But then again, I would love the excuse to have to build an entirely new rocket! Greg, when you converted to dual deployment, did you have to buy a new upper tube as well?
Thanks guys!

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I bought 2 38mm Aerotech RMS Motor Assemblies. I have a 38/360 and a 38/600. There is a 38/480 in between. I've only used the 38/360 and whith the reloads available I've hit 2800'. Check out their dimensions and make the motor tube as long as the 38/600 is. I can't imagine launching it on anything higher.

As far as the tube I can't remember. I'll go out to my shop tomorrow & get you the measurements.

MidLifeMike said:

I really can't even imagine flying a 54mm motor at this point, but I once read in a thread to always use the largest MMT that you might ever imagine using.... Sooo, I had already ordered both the 54-38mm and 54-29mm adapters. I have a feeling I'll be using adapters 99% of the time, but hey, you never know!

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This should make you think about motor retention. Typically we now all use either Aeropack retainers or slimline. (There are a few others, more exotic, but less common.) The 'old school' way was to "friction fit" the motor int eh tube with layers of tape. I'm not too fond of the LOC adapters, and they are all cardboard tubes with no motor retention: you'll either need to add one, or rely on the friction fit method.

Aeropak have the retainers, and adapters. The system is very easy to use, and is easily switched form one rocket to another. This might be the better way to go (that's what I would do / recommend to you..)

Yes, we all say to build it for the biggest motors you plan to fly. 54mm is big, and is typically the beginning for L2 flights. Do you plan to start flying 54mm motors in the next year or two? My opinion is, to make it a 38mm MMT rocket, and fly the snot out of it! Use it for your L1, use it for your DD trials, use it for ... Then, either buy another one, or buy another 54mm capable rocket for when you plan to start using 54mm motors / get your L2. (Also, going the 38mm route, you will have less weight at the tail end. You will, however, need to fabricate new fins, with longer tabs to reach the smaller MMT.)

LOC has some nice aluminum motor retainers. I'm using a 38mm.

https://locprecision.com/product/loc-pro-motor-retainer/

MidLifeMike said:

I would like to eventually set it up us as a dual deploy in the future. But then again, I would love the excuse to have to build an entirely new rocket! Greg, when you converted to dual deployment, did you have to buy a new upper tube as well? I'm half debating whether I should just buy one of those kits now and incorporate it for when the time comes.

Thanks guys!

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Mike, I attached an OpenRocket ork file of what my dual deploy Caliber looks like. I did check my digital purchase orders from LOC & I must have added some tubing somewhere. I hope this helps. If you don't have OR go to this thread & follow the instructions.

https://www.rocketryforum.com/threa...d-mac-to-solve-all-your-java-problems.143540/

Greg Furtman said:

LOC has some nice aluminum motor retainers. I'm using a 38mm.

https://locprecision.com/product/loc-pro-motor-retainer/

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Those are pretty cool!! I wasn't aware of them! (I guess they are fairly new!)

I wonder if they are interchangeable with Aeropak..

Thanks a ton for the ORK file Greg. I've already played with that quite a bit. When the time comes, I'm fairly certain it will become a dual deploy. I'm tempted to order the upper tube and the electronics kit from LOC right now before I paint, so that I can have two interchangeable setups.

So I changed my mind on the baffle..... I've modified it to 4 inches and I feel that I have enough space now anyways. One of the bonuses for me was that it included an eye bolt and I did not have to work about gluing the shock cord to my motor mount. Maybe I'll regret keeping it, but I learn better from my mistakes/regrets. At least the parts won't be sitting in a box gathering dust, and it will be educational to see how it works regardless (although I did modify the design from 6 inches down to 4, so I hope that does not affect its performance too much).

And I chopped 3 inches off my MMT. That puts me at 14 inches, plus the 1 inch up to my baffle....Looks like the largest motor I could fit might be an Aerotech K535 or something similar, lol. I know, I'm way ahead of myself and will probably own 5 more rockets before I'm even at that point.

As for the motor retention, I did buy the aeropack 54mm retainer when I bought the kit. I'm pretty invested in the 54mm motor mount at this point, as silly as that might be. And the added headache of the fin tabs. Hopefully I can certify Lvl 1 at NYPower in May and by 2021 I'll be flying 54mm motors!

I included an updated picture.... I've gone from 6 inches of recovery space to 11 inches....I think I'm in the clear now.

MidLifeMike said:

Thanks a ton for the ORK file Greg. I've already played with that quite a bit.
As for the motor retention, I did buy the aeropack 54mm retainer when I bought the kit. I'm pretty invested in the 54mm motor mount at this point, as silly as that might be. And the added headache of the fin tabs. Hopefully I can certify Lvl 1 at NYPower in May and by 2021 I'll be flying 54mm motors!

I included an updated picture.... I've gone from 6 inches of recovery space to 11 inches....I think I'm in the clear now.View attachment 405707

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If you get a 54mm to 38mm motor adapter you will need (I think) a 38mm retainer. I mentor a Tribal College Rocket Team and a couple of years ago they built a Publis Missiles AMRAAM 4. It's 54mm motor rocket but the competion reguired a 38mm motor. So we bought their Kwik Switch motor adapter system.

https://publicmissiles.com/product/motormounts

And we also bought their HAMR-KS Retainer System which is pretty slick.

https://publicmissiles.com/product/motorretainers

No need for a 38mm retainer with the 54-38mm aeropack adapter. You can even nest in a 38-29mm and fly some high impulse 29mm motors if you want

When I built my last LOC rocket with a baffle, I used the baffle to permanently join the airframe and payload sections. This also allows the chute to not slide down the airframe under boost, as well as not needing a Kevlar chute shield. Worked out very well, I think. Less recovery harness needed too, since you can easily mount one to the top of the baffle.