# Hell Boy > 19 motor cluster

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#### delta22

##### Well-Known Member
Always wanted to build an upscale Fat Boy, and Polecat's 5.5" Fat Man is a good kit to do it with.

Holy crap $58 per launch....hope they all ignite!! :jaw: also subscribes op: #### HotRod Rockets ##### Well-Known Member Excellent Name. what no -In-ate-or? you can always nick name it.... Smoke-in-ate-or.. What's the ETA on this one Fall '10 or Spring '11 ? I don't want to miss this one. ------ Rocket -E-Gator I just did the math for Estes D12's (At Hobby Lobby bought a 3pack @ 30% off$9.10) 19/3=6.33 6.33x9.10=57.607
You can't measure it in dollars and cents. Or in Newtons of Thrust.

You have to measure it in Gigawatts!

.

#### gdiscenza

##### Well-Known Member
TRF Supporter
1.21 Gigawatts?? This thing'll recover in 1985!!!

G.D.

#### powderburner

##### Well-Known Member
delta22,

Was there any particular reason to arrange the outer dozen MMTs near the circumference, instead of "honeycomb" dense-packing them together with the center seven?

#### rstaff3

##### Oddroc-eteer
I don't know how he actually plans it but the chances are this is just what popped out of RockSim and, for that, was close enough.

#### delta22

##### Well-Known Member
delta22,

Was there any particular reason to arrange the outer dozen MMTs near the circumference, instead of "honeycomb" dense-packing them together with the center seven?
I don't know how he actually plans it but the chances are this is just what popped out of RockSim and, for that, was close enough.
Exactly correct.

To model this complex a cluster mount in RockSim I had to add:
1) one central motor
2) a ring of 6 around that
3) a ring of 12 around that one

Interlocking of motor tubes is not depicted accurately in the model.

It is a "honeycomb" in the real thing, for simplicity of build, motor density and strength.

#### delta22

##### Well-Known Member
Reloads or Estes??? I just did the math for Estes D12's (At Hobby Lobby bought a 3pack @ 30% off $9.10) 19/3=6.33 6.33x9.10=57.607 Holy crap$58 per launch....hope they all ignite!! :jaw:

also subscribes op:
Yes, launches won't be cheap.

However, big clusters are typically about the price of a single motor with twice the impulse.

As David noted above, it's really more about effect than altitude in a project like this.

#### DAllen

##### Well-Known Member
D12 = 16.8 newtons

16.8 x 19 = 319.2 newtons

#### delta22

##### Well-Known Member
Boris, with all those plugged tubes, what are your plans for the D12's? Or are you actually thinking about D11's? On my 10 D cluster, I plugged D12-0s for 9 of them and then used the other for ejection. I ran into a hobby shop which found a huge box of D12-0s and they were dumping them for \$3.50!
Only the center tube is plugged (against the bulkhead).

The 18 surrounding tubes have a 1/2" gap from the bulkhead and could vent their ejections through the open spaces surrounding the motor honeycomb.

That said, I will use D11-P motors to avoid scorching.

For some flights will put one ProX 24mm F30 White in the middle. The effect of the white AP flame surrounded by BP jets is very cool.

pic 1: A motherload of D11-Ps (150 motors) I picked up from Hangar 11 recently when Estes told me they had done a production run.

pic 2: Upscale (2x) FlisKits Thunderbird going up on a central F30 and 10x Estes D motors. Also planning to repeat this flight on 11/6.

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#### rstaff3

##### Oddroc-eteer
Here's the only launch shot I have of my Massive Gassive.

#### troj

##### Wielder Of the Skillet Of Harsh Discipline, Potent
How do you ignite all of these? Test igniters, and build a serious clip whip? Or do you do something else?

-Kevin

#### rstaff3

##### Oddroc-eteer
I personally cheat....quickmatch all the way for bug BP clusters. Lit with an Estes igniter.

#### delta22

##### Well-Known Member
How do you ignite all of these? Test igniters, and build a serious clip whip? Or do you do something else?

-Kevin
I have used Rocketflite MF ematches and ML igniters with very good results. For bigger clusters I have started using a cluster box to supply lots of current.

I never use a whip clip, as they create many points of electrical failure. The Rocketflite products, and some of the others, have long insulated leads, allowing them to be directly joined.

A number of threads I started have pictures of the igniters and cluster box in action.

#### delta22

##### Well-Known Member
I personally cheat....quickmatch all the way for bug BP clusters. Lit with an Estes igniter.
I've only done a few experiments with quickmatch, with mixed results.

How do you set yours up?

#### delta22

##### Well-Known Member
Here's the only launch shot I have of my Massive Gassive.

Did a search but found nothing on this forum.

#### rstaff3

##### Oddroc-eteer
I have had good luck with the quickmatch. The 10-motor Massive Gassive is my biggest 24mm cluster and my 12-Pack is my biggest 18mm (check out the video link in the EMRR review). I can only remember one failure...on a 2-motor Deuce :y:

Here's my set up. I insert two ~6" strands of quickmatch (it comes packaged with 5 pieces sheathed in an outer covering) in the nozzle of 24mm motors and one strand in 18mm. The extra strand in the 24mm motors is overkill but I have a lot of it. I'll probably eventually regret not conserving . I use another short piece to wedge the long strand(s) in. I then use masking tape to hold the match in place. After the motors are installed, the strands are pulled together and taped about one inch from the bottom. An igniter is then slid into the bundle. Earlier, I said I used an Estes igniter but actually usually use something else since the short leads don't work well with big clips on HPR pads.

I think the one failure was because only one strand lit on the pad. On small clusters, I now stick some extra in the tape bundle to make sure there is a nice fireball to get all of the strands lit.

Like I said, this is kinda like cheating (and of course, will only work on BP motors). I've also used a central composite, which ignited the quickmatch for the outboards.

#### delta22

##### Well-Known Member
Thanks for the info Dick and CJL.

Painted the inside of the recovery area with thinned epoxy for fire resistance (West 206 + 25% alcohol by weight). The 38mm internal tube is for the altimeter and the 3" internal tube is for the main.

Started to build the altimeter sled. Alt vent hole can be seen mid-body. It directly enters internal 38mm tube.

Added 7x threaded rods for retention, 3" long 8-32, with 3/4" exposed. Also painted the inside of the motor tubes with thinned epoxy for physical and fire hardening.