Cluster Duck

Got two great flights out of my Cluster Duck on Saturday at the UROC Cinco de Mayo launch. I planned on building a boost box as described on https://bpasa.com/Cluster-box.htm, but didn't get it done in time. I went ahead and followed Boris and Paul's advice and wired the seven motors in two strings of two igniters and one string of three igniters, so a combination of serial and parallel. I use some of my precious Q2G2's and dipped them in QuickDip (https://www.quickburst.net/quick_dip.htm) as extra insurance. All fourteen motors lit instantly leading to two awesome flights.

The first was loaded with 6 x B6-0 + 1 x E9-4, and the delay was a bit short (as predicted by RockSim) to around 800'. The second was 6 x C6-0 + 1 x E9-8, which simmed as a bit long, but looked perfect from the ground, to around twice as high. Due to better rail pointing the second flight actually landed closer to the pad than the first.

On the pad, ready to attach the clips:

Waiting to push the button:

You can see some of the outboards are still coming up to pressure:

By the time it came off the rail, everything was burning.

Under one of my wife's beautiful chutes. Maybe I'll use the JLCR next time!


I've got to say this rocket was a ton of fun to fly, if not to build (finishing 6 fins gets old REAL quick). The flights are SMOOTH and stay within sight (and within site). Lots of fun to be had with black powder motors. I think this bird earned a paint job!

I saw this flight on Saturday. It was great! You should download these photo's onto the UROC website.

I put them on the UROC Facebook page (https://www.facebook.com/groups/urocfb/), including some nice shots of your N1. I'll see about uploading them to the website, but there are 124 photos that my brother took at the launch.

Dugway said:

I put them on the UROC Facebook page (https://www.facebook.com/groups/urocfb/), including some nice shots of your N1. I'll see about uploading them to the website, but there are 124 photos that my brother took at the launch.

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Clair, those are terrific photo's. I don't do facebook, but I was able to look at the pictures. Unfortunately, I pushed the wrong buttons on my camera and lost my N1 photo's, but my wife has some on her smart phone.

If you aren't able to download them from FB let me know and I'll get the originals to you.

I have one of these and love it. Best flights are 1 X D12-5 and 6 X C6-0. Delay is near perfect.

One day I might be a big boy and go 1 E30-7 and 6 X D21...

This rocket has really reminded me of how much fun you can have with black powder motors and no electronics, etc.. OK, maybe a chute release.

I've been eyeballin' this one for a couple weeks. I'm sure it will find it's way to my door soon!

Why did you arrange your igniters in series and parallel?

Why did you add dip to Q2G2"s?

Following Boris Katan's extensive experience, I used a combination of serial and parallel, with strings of 2 or 3 igniters in serial connected in parallel in a 2-3-2 configuration. I dipped the igniters because I have the QuickDip and I've been using this combination for some time to light small composite upper stage motors.

I launched my Cluster Duck three times at HellFire, the first on the enhanced Q2G2s, the second and third on MJG's BP Rocket Starters. Unfortunately, the final flight will be its last. I prepped the motors and igniters the night before, and forgot to put a parachute in it when I launched it the next morning.

So, the last two rockets I've destroyed have been caused by leaving a rubber band around a parachute and forgetting to put in a parachute at all. Maybe time for a checklist.

Dugway said:

Following Boris Katan's extensive experience...

Click to expand...

Could you provide me a link to where Boris discusses the rationale for this arrangement.

Thanks

Forgetting a parachute is a bad mistake. Don’t rush the prep.

https://www.bpasa.com/Rocketflite.htm

https://www.bpasa.com/Cluster-box.htm

Maybe I've just been lucky, but I've flown my Cluster Duck three times on unmodified Estes igniters all wired in
parallel, and I've been 3 for 3. All 3 flights completely successful, all 7 engines fired each time. I did this at 3 different clubs
so it wasn't as if one club had a particularly robust launch system. I point one lead of all the outboard igniters outwards, and the other leads inwards.
I tie all the inward leads together, and the outward leads are all tied to a circular bus wire. I'm also able to attach one lead for the center igniter to the outer bus wire and the other lead goes to the inward tie. I've attached some photos. The Cluster Duck is one of my favorites!!

Very cool. Any pics of the series/paralell arangment?

Here's my second Cluster Duck going up on an E12-6 and 6 x C6-0's at the UROC 2019 Cinco DeMayo Launcho. As you can see from the enormous clips, I'm using my LiPo boost box. I've used it four times now and all motors light every time. I'm using seven MJG BP Rocket Starters wired in parallel, as suggested by the manufacturer. I've also started plugging the C6-0's with epoxy, and boy does it cut down on the amount of damage to the rear end of the rocket. All UROC launches are conducted as Tripoli Research launches, and I'm launching from the mid-power pads off a 1010 rail, so I feel pretty comfortable doing so. A JLCR fits great and brings it down nice and close to the pad. This is a great rocket and I'm sure I'll build another after I love this one to death.

Nice picture and good background information! BP motors are fun, especially for clusters, but the soot can mean a lot of post-flight clean-up.

I like the black fins.. hides the soot!

Yeah, it's Rustoleum Engine Enamel. It seems to be holding up well so far. Another thing I like on this rocket, I was too lazy to airfoil six fins so I 3D printed rounded leading and sharp trailing edges and glued them on before priming, sanding, and painting. Still no signs of anything coming loose!

Always fun to see your ClusterDuck fly! The Cinco launch was fun.

A series-parallel combination gives a different net resistance than all parallel or all series, intermediate between the two. The best energy transfer from the power source to the cluster comes when the cluster's net resistance is equal to the source's source resistance. Without knowing said source resistance or the single igniter resistance I can't say what the optimal configuration would be, but that's generally the reason for such an arrangement. 2-3-2 gives a net resistance of 3/4 the single igniter resistance. 4-3 would give 1-5/7.

Also, with the a seven motor cluster of six around one, 2-3-2 is geometrically convenient.

Great illustration. This is exactly how I wire up Q2G2's and never have had a failure. When I tried this with the BP Rocket Starters when they first came out, it was hit or miss. Shortly thereafter MJG added the "parallel only" wording. I haven't had another MJG failure since switching to all parallel and the boost box. Now to try a mix of composite and black powder motors, or maybe all composite with six Quest 18mm motors and a central reload...

I tend to think that small, say 24 mm, composite motors can sometimes be difficult. Some people recommend igniting the composite motor first and then ignite the BP motors.

That sounds interesting using a LiPo in a boost box. I have a Cluster Buster Box made by Quick Burst. It is a relay box that uses a car or motorcycle battery, which is cumbersome. I used it to ignite two 29 mm composite motors and it worked fine. However, I haven't used this Cluster Buster in several years. Currently, I am igniting BP clusters with Blackjack's e-matches with good success.