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tomsteve

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There is not a whole lot of room. The body tube comes down over the motor tubes quite a ways and covers the end of the engine blocks, so the vents need to be above the bottom of the BT. So, the only place to vent is on to the fins. It is why I painted all the fins black, I already figured they were going to have to deal with a lot of exhaust gases.

Couple pics to illustrate what I mean. The blue tape marks the top of the engine block inside the motor tube. The vent hole needs to be above that. As you can see, when the body tube is installed, it comes down to the tape line, so any vent hole that takes advantage of the space between the fins will have to vent the gases onto the fins.

Open to suggestions if I am missing something.
if you have access to the engine block you can drill through that. remember- the top of the motorbis below the engine block
 

StanO

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Boris wrote his Cluster Box instructions quite a few years ago. I've gone back and found what I used to build mine, in case anyone is interested.

I found my Amazon order from Spring 2018 that looks like it was the Crown Vic solenoid and the 12v relay that I used:

Standard Motor Products SS598 Solenoid
E Support Car Relay 12v 40a Spst 4pin Socket Pack of 5

I really think any 1990 Crown Vic solenoid would work (probably along with many others). As Boris explains, the key is that the solenoid have a clamping diode so you don't damage the launch controller. I bought a five pack of relays on the assumption that they wouldn't last long with all that current, but I'm still on my first one.

The battery I use is from Hobby King, it looks like it has been discontinued, but I'm sure you can find something comparable:

Turnigy Bolt V2 1300mAh 4S 65~130C High Voltage Lipo Pack

The only other major components are a 300 Amp two position rotary switch to turn the whole thing on and off, a digital volt meter I had kicking around to monitor the battery voltage, and some very heavy gauge cables (2 gauge maybe?) to get from the LiPo battery to your rocket. The circuit from the launch controller to the 12v relay can be MUCH lighter weight. There are plenty of online calculators to help you figure out wire diameters for voltage/current/length.

I put the light weight clips that go to the launch controller on banana plugs to make it more easy to store/replace them and mounted everything in a cigar box:

View attachment 430610
I requested the copies of the issues from NAR that have the instructions for the Cluster Box a couple of weeks ago and haven't heard from them or received anything. Slow mail or whatever. If you don't mind could I get a copy from you? You can PM me.

Thanks, Stan
 

mtnmanak

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I requested the copies of the issues from NAR that have the instructions for the Cluster Box a couple of weeks ago and haven't heard from them or received anything. Slow mail or whatever. If you don't mind could I get a copy from you? You can PM me.

Thanks, Stan
Do you need a print copy of the whole issue? You can always login to the NAR site, go to the Sport Rocketry Magazine Archive under "Member Resources" and then go to the JANUARY/FEBRUARY 2012 VOLUME 54, NUMBER 1 issue. You can either download the whole issue or print out the article only. It begins on page 16.

Boris's Cluster Box page at http://bpasa.com/Cluster-box.htm has almost the same info as the Sport Rocketry article, except Boris's site has more detail about the testing.
 

Dugway

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I built my Cluster Box entirely from the information on Boris's web page. You have to stare at a couple of the pictures to figure out the wiring, but if I can do it, anybody can. Does anyone know of a good tool for creating schematics? It would be a hassle to do it the first time, but going forward there would be much less confusion.
 

mtnmanak

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I built my Cluster Box entirely from the information on Boris's web page. You have to stare at a couple of the pictures to figure out the wiring, but if I can do it, anybody can. Does anyone know of a good tool for creating schematics? It would be a hassle to do it the first time, but going forward there would be much less confusion.
I often use Visio for schematics, it is usually enough for the things I need to do.

This tool is free and I played around with it for a few minutes, looks pretty good: https://www.circuit-diagram.org/
 

mtnmanak

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I have all the parts and pieces for my cluster box, but haven't put it together yet.

Also, I did fly my Cluster Duck this weekend! Great launch - went up about 400 feet on 6 x B6-0's and 1 x D12-5. It was a great day with almost no wind and all 7 motors fired, the Duck flew straight and recovered only 10 feet from the pad. Great flight. Next time, I will push the limits on it a bit, but great first flight.
 

Back_at_it

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Kinda jealous of you guys that flew the Duck this weekend. I had a great outing myself but I was trying to get everything that had not flown up in the air so I left some of my favorites including my Duck clone at home. I've never flown it on a cluster but it's still pretty impressive on single E12-4
 

mtnmanak

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Love this Cluster Duck. It flew so well, I am going to up the ante with the motors next time, but I am also planning to build a bigger clone on a 4" airframe. I also have a few US Rockets clusters in the build pile to get to, so will hopefully have a number of large cluster rockets to fly this winter / next spring.
 

mtnmanak

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Also, a couple notes on some of the discussions earlier in the thread:

I did drill the vent holes in the 18mm tubes, but I flew at a Tripoli launch last weekend that allows research motors, so all the 18mm motors were plugged with epoxy. Small amount of tape gave them a friction fit. All fired properly and had no issues with the ejection charges. All motors stayed in place. So, I didn't really test the vent holes this time around. Will check out their performance if I bring it to a NAR event or forget to bring plugged booster engines. It is nice to have zero residue in all those motor tubes at the end of the launch! For the heck of it, I may try a flight next time with the ends of the 18mm engines stuffed with dog barf and sealed with aluminum tape. Would like to know how that config works out.

I thought the parachute may be too big, but, since there was virtually zero wind, it was difficult to judge what the drift/descent rates would have been like on a windy day. For this launch, the 36" Dino chute was exactly perfect, so will stick with it for the time being
 

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