# 3 x 5 (.38") - A cluster of cluster build threads (Alt. Title: Three O'LOC)

### Help Support The Rocketry Forum:

#### 75Grandville

##### Well-Known Member
This all got started around Black Friday when Mr. Bob has his inexpensive shipping sale. I'd been playing with the idea of cloning some LOC rockets. Using all LOC parts - I just like to figure it out on my own. Plus I like to tweak things. Then I got to thinking, which is always dangerous.

The original plan was to build three sustainers, with a common AV bay and N/C. Originally, I was looking at the LOC Cruiser, the King Viper III, and something completely different, working title of I-19: Thunder Road.

So, the parts began to arrive. Two 42" lengths of 5.38" tube. 5 x 54mm Motor mount tubes. One 5.38" AV Bay, and one 5.38" payload section. 6 54mm in 5.38" centering rings.

And I started thinking about what I was going to build. Thinking about adding motors to one set of the 54mm Crs. But no actual building yet.

Christmas came, and Santa brought a 72" and an 84" Rocketman chutes - depending on configuration, these should do the trick.

#### Nytrunner

##### Pop lugs, not drugs
TRF Supporter
It'll be cool to see a Cruiser take shape. I'm planning to mess with one and turn it into my L2 in the future.
Did you have to increase the rear fins to account for the extra motors and forward wing-fins?

#### 75Grandville

##### Well-Known Member
It'll be cool to see a Cruiser take shape. I'm planning to mess with one and turn it into my L2 in the future.
Did you have to increase the rear fins to account for the extra motors and forward wing-fins?
Meh. My bad. Meant Magnum. Cruiser was on the original list, but was dropped (for now). That's what I get for trying to type things up in a hurry.

#### Nytrunner

##### Pop lugs, not drugs
TRF Supporter
Meh. My bad. Meant Magnum. Cruiser was on the original list, but was dropped (for now). That's what I get for trying to type things up in a hurry.
Disappointment.
Does nobody do the Cruiser? At least my build thread will be unique lol.

Either way, looks like you've got a nice set of projects ahead of you. Planning to do single use motors in the 29 slots?

#### 75Grandville

##### Well-Known Member
Disappointment.
Does nobody do the Cruiser? At least my build thread will be unique lol.

Either way, looks like you've got a nice set of projects ahead of you. Planning to do single use motors in the 29 slots?
Yeah, 20 x 29mm SU motors (10 x G80 and 10 x G125) on the way from Balsa Machining plus a J800T, along with 3 x 38mm SU H219T for my TriStar. That's enough for two flights of El Monstruo - one with just 8 x 29 (4 x G80 and 4 x G125), and a second matched flight with the J800 in the center hole.

The cost of rocketry seems to keep going up!

Added first set of internal fillets today for the fin-can. Had a couple minutes between an early-morning conference call and the roofer coming to do the final walkthrough on my new (and expensive) roof. I could buy 825 of those SU G80 or G125 motors for what my new roof cost!

#### ECayemberg

##### Well-Known Member
Bill,

Watching with interest! I like the way you think and can't wait to see how these cluster creatures turn out!!!!

#### 75Grandville

##### Well-Known Member
Bill,

Watching with interest! I like the way you think and can't wait to see how these cluster creatures turn out!!!!
Eric, thanks. I watched your Top Gunn etc. thread with a mixture of awe and envy.

At this point, it's safe to say one of them turned out wrong. At least for now.

I had glued both pairs of 54mm MMT tubes together, then peeled a small section of the glassine layer to epoxy the four into a single unit.

I had carefully laid each pair on the floor to make sure they set up parallel to each other. Unfortunately, I did not do the same when I attached the pairs to each other. The result: a slight but noticeable misalignment at the aft end. Discovered tonight after I whipped up a batch of epoxy to start attaching the fins. Gonna need to get some more tubes, I guess.

I did get the centering bits laid out on some scrap left over from the fins. Need to get my scroll saw out of storage - jigsaw isn't going to cut it. Ha. Cut it.

I did start gluing up the motors for I-19. Right now they are in strips 3-4-5-4-3, but I dry fit them together just for the nice visual, and to make sure they fit the centering ring I'm planning to use.

Used that batch of epoxy to do the last two sets of internal fillets for El Monstruo.

#### 75Grandville

##### Well-Known Member
Another Sunday, some more building.

Marked the BT for fin slots, then cut carefully, using an exacto knife and multiple passes.

First dry fit. Apparently things are not exactly 90 degrees between each fin, as the fin assembly got stuck. Had to use a 54-2560 motor as a slide hammer from the other end to bang everything loose.

Figured out the correct orientation, and made some marks so that I don't go through that again.

Added sleds to the AV bay, with C channel to guide them in place. Should be able to fit 2 x RRC3's on the long one. The second one may hold the batteries - still working on the final layout.

Realized that this is probably the place to put the attachment for the shock cord, so stainless U bolt added as well.

Think I'm going to lop about 6" off the central MMT tube. Not needed, and will give me more room for the drogue and shock cord.

Also got my scroll saw out of storage, and started cutting bits to go around the motor tubes for Overkill (2.0, the one that I'm going to build with properly aligned motor tubes). All I can say is that scroll saws are harder to use than they look. Sanding will be required.

#### tomsteve

##### Well-Known Member
Also got my scroll saw out of storage, and started cutting bits to go around the motor tubes for Overkill (2.0, the one that I'm going to build with properly aligned motor tubes). All I can say is that scroll saws are harder to use than they look. Sanding will be required.

View attachment 313236
the scrollsaw just requires practice.

Gorgeous build Bill..
I promise you you're going to absolutely love flying this ...
With all of the different combinations and start times...
Endless fun...

Teddy

#### 75Grandville

##### Well-Known Member
Gorgeous build Bill..
I promise you you're going to absolutely love flying this ...
With all of the different combinations and start times...
Endless fun...

Teddy
And of course some of the best recovery harnesses in the world!

Realized today that I am hoping to fly at least one in less than three weeks, and I forgot the harness!

Last edited:

And of course some of the best recovery harnesses in the world!

Realized today that I am hoping to fly at least one in less than three weeks, and I forgot the harness!
That's OK Bill,,
I'll get them right out as soon as we're done giving them out...

I'm not kidding man,,
Check this sequence of pics of my rocket "Europa Express"...

Oops,, you may have to go here,,

I have had a ball flying this,, different loads,, lighting at different times etc...

You have more possibilities then you could hope to exhaust ( get it,, exhaust,, get it )...

Wad r u going to use to do the airstarts Bill ???

Teddy

#### 75Grandville

##### Well-Known Member
Going to use a pair of RRC3's in the booster to control the airstarts. That's probably not until this summer. First, I need to get a couple successful flights in where all the dang motors actually light. Then try to get them to light in sequence!

#### 75Grandville

##### Well-Known Member
AV Bay taking shape. Assembled a stock LOC 5.38" electronics bay some time ago. Just added charge wells (3/4" copper end caps) to both ends. Waiting on crimping tool to finish up the actual wiring.

Will switch out stock eye bolts for forged once my order from eRigging arrives.

#### 75Grandville

##### Well-Known Member
Threw my back out this weekend. Was doing great, took the kids to the playground, and spun them on one of those merry-go-round things. The next day (Sunday) things got bad.

Today's tip is: don't work on your rocket if you are in great pain. It will not come out well.

I carefully drew up a template for the electronics hatch on El Monstruo. Measured, measured again. Aligned carefully. Cut out hatch. And was off by about 10 degrees.

I had to take the motor mount assembly out, pry off the channel that's hidden behind the left hand side of the wall next to the hatch, and epoxy it back down at a sharper angle. And trying to get the motor mount back out of the body tube while your back is yelling at you is so not a good idea!

Not sure if the rockets will be ready to fly on the 18th, and even if they are, not sure I'm going to be able to chase them!

Like the title says: crap.

#### 75Grandville

##### Well-Known Member
And that "Oh Crap" turned out to be a ruptured L3/L4 disc, pressing on the nerve to my right leg inside the L4 vertebra. 7 weeks of conservative treatment later, and not all that much different. Epidural Spinal Injection on Thursday, really hoping that is going to make the difference. Otherwise, who knows when these will get finished!

Did not make the March 18th launch. Maybe the May 20th launch. If that goes well, then I'm off to the NSL.

As you can see, I have been working on these, albeit very slowly. El Monstruo has gotten fillets mostly finished, on a "good back" day. Unfortunately, those seem to be fairly rare.

Going to see whether I can start marking the bottom tube for I-19. The motor tubes for Overkill are still in my office, 45 miles away.

Suscribed.

#### grouch

##### Well-Known Member
Sorry to hear about the L4/5 issues. Back stuff sucks. Good luck on the recovery. I will be watching the build as I am a sucker for a cluster job.

I sure am sorry to hear of your back problems Bill..
They're no joke for sure..
Feel better man...

Teddy

#### 75Grandville

##### Well-Known Member
You can cut fin slots while in bed. Just be careful!

Slots cut for I-19, and I-19 fin can (sans fins) shown with payload section that will be common to all three. 808 camera shroud attached to payload section.

Also started working on fin can for I-19. Am planning to notch top centering ring (98mm in 5.38") to accept fins. 1/4" should be enough. I'm also planning to be able to use different size motors. 13 x F15-8, 19 x E12-8, 19 x D12-5, or 19 x C11-3. So, the motor mount/fin can needs to be able to accommodate three different lengths: 4.5", 3,75", and 2.75" with the last being the least important.

Planning to glue the motors together with wood glue, then use fore and aft centering rings as retaining rings. So I started thinking about a .75" spacer to use with the E12's. Then I got clever (maybe). Why not notch a second centering ring so that the 29mm motors will slip through, but the24mm 3.75" motors will be held at the proper height.

I printed out a template, used a glue stick to stick it to a 75mm to 5.38" CR, and cut out the middle. My idea is to cut out spaces for the 29mm motors, and glue this to the forward CR with half inch blocks between. That gives me a second CR to lock the fins in place, also.

More pics as I progress. I've got a good mental picture, but no good way to draw it out, so if it's confusing just stay tuned!

#### 75Grandville

##### Well-Known Member
Wow, it's been a while. I wound up having back surgery in June (which went really well), and couldn't do much after that. I really wanted to get at least one of these done for Hellfire 22, but just couldn't swing it. However:

El Monstruo is complete, and flew at our October launch. 7 out of 8 G80's lit, apogee was 1866'. w00t!!

I painted it over the summer. Purple metallic with orange fins.

Did my ground testing before it flew. No pics of that. It takes 1-1/2 of those little plastic vials of FFFg black powder (yes only 3 F's) for each ejection charge.

I dipped my own ignitors for this one. There was concern about the ability of the launch system to ignite all at the same time, so we did a dry fire of 8, and it passed with flying colors.

Special thanks to Jed M for his assistance at the pad. Took forever to get all 8 ignitors in, wired up, then try to reach the dang screw switches way inside the body tube!

Anyway, it flew, and it was awesome. A/V bay held an RRC3 and a StratoLogger. Grateful for the redundancy, as one of my solder joints broke on the leads to the ejection charges. Recovery was handled by an 8' RocketMan chute. This is what I managed with my phone. Going to try to post the launch video too.

Was a very mixed day - 4-29SS got kinked in the car and couldn't fly. TriStar flew awesome, but came in ballistic. I salvaged the fins. But seeing El Monstruo fly was just awesome. A year of work +/-, and the results were great.

The other two are still in process. I'll get there.