13mm clustering

[neil_w]

Not sure why I'm wondering about this, but... is 13mm clustering worth the trouble? Is it fun? Have there been any 13mm clustered kits? (I suspect the answer is "yes" but don't know what they might have been).

I haven't tried to figure out how big a rocket 3 A3-4Ts could lift, just pondering the general possibility.

 

[Nytrunner]

Delay time is the limiter from what I've heard. Unless the rocket is draggy/heavy, a cluster can quickly outpace the included -4 delay times and you get early deployment.

Workaround is to stick an 18mm sustainer motor as the core motor with leetle 13s clustered around it.


Is it worth it? If you want to make a rocket you haven't done before, yes!

 

[Jeff Curtis]

Rocketarium Trident-13 is an example. I just built the Trident 18 and will launch it on Sunday. I would not be opposed to trying the 13mm version.

 

[Dugway]

US Rockets has the Micro Interroc with interchangeable motor mounts, one of which is 3x13mm:
https://v-serv.com/usr/kits/micro-interroc.htm

It's a pretty beefy rocket and didn't get very high when I launched in on 3xA10-3Ts.

 

[BABAR]

deleted, misread post, read “staging” instead of clustering

 

[BABAR]

Should be just as much fun as any other cluster, with the added bonus of the motors are cheaper!

 

[neil_w]

Delay time is the limiter from what I've heard.

Ah yes, good point.

Unless the rocket is draggy/heavy, a cluster can quickly outpace the included -4 delay times and you get early deployment.

I know a thing or two about draggy rockets.

Is it worth it? If you want to make a rocket you haven't done before, yes!

My only cluster so far is a Deuce's Wild. I feel like I should do another. Dunno why I'm thinking of 13mm, other than that makes for a cheap cluster flight.

On the other hand, my supply of black-tipped igniters is almost exhausted, so that is an issue...

 

[Charles_McG]

My first scratch build as a BAR was a 13mm downscale of the Little Beth X2 design of the month club rocket. clustered and staged - all 13mm.

 

[Rocketjunkie]

I have a stock size Fat Boy with 12 13mm mounts. I originally built it for C20/D40 (Rx) motors but it has flown on 12 A3-4s. It has quite a bit of nose weight since it's balanced for C20s.

The final pic is the Rx D40. 1/2" diameter, 5-5/8" long.

 

[kuririn]

is 13mm clustering worth the trouble? Is it fun?

Yes.


13mm downscales: Tres, Enerjet 2250, Deuces Wild
EDIT: Oops, sorry, that's the 18mm 2250. I have the 13mm somewhere, it's similar to the Rocketarium (ARG) Trident 13mm.

 

[kuririn]

PS Rocket Garden still has this in stock:
https://therocketgarden.com/FlisKits/emk2_13_55c.htm
But if you snooze you lose.
Have fun.

 

[SDramstad]

Ah yes, good point.

I know a thing or two about draggy rockets.

My only cluster so far is a Deuce's Wild. I feel like I should do another. Dunno why I'm thinking of 13mm, other than that makes for a cheap cluster flight.

On the other hand, my supply of black-tipped igniters is almost exhausted, so that is an issue...

Try a flash pan. Only one igniter needed.

 

[Rocketjunkie]

I used a flash pan for the 12 motor Fat Boy. However, for reliability, I inserted a short piece of fast fuse in each motor.
The clear tape is coated with BP to light the fuses.

 

[BRS Hobbies]

I say why not. You can also use at least one of the Estes 13mm plugged engines.

 

[Scrapmaster87]

The A10-0s make excellent strap-on motors.

 

[scadaman29325]

The A10-0s make excellent strap-on motors.

Newbie question, would A10-PT be better? Wouldn't the -0 ejection charge hamper the forward momentum? Or if the -0 was slipped into a plugged motor mount without much of a retainer, it may help boost the rocket as it is blown out the rear of the rocket...???

I'm liking this idea.

Phil.

 

[Scrapmaster87]

The idea of a strap-on is that the motor is in its own separate airframe. The -0 provides the ejection at burnout so the main body of the rocket can continue under thrust without the dead weight of the boosters. If you're not dripping your boosters then yes the -pt is better suited.

Newbie question, would A10-PT be better? Wouldn't the -0 ejection charge hamper the forward momentum? Or if the -0 was slipped into a plugged motor mount without much of a retainer, it may help boost the rocket as it is blown out the rear of the rocket...???

I'm liking this idea.

Phil.

 

[Charles_McG]

The idea of a strap-on is that the motor is in its own separate airframe. The -0 provides the ejection at burnout so the main body of the rocket can continue under thrust without the dead weight of the boosters. If you're not dripping your boosters then yes the -pt is better suited.

Because even though a -0 motor doesn't have an ejection charge, the burnthrough is usually energetic enough to pop a nose cone by itself.

 

[BABAR]

Newbie question, would A10-PT be better? Wouldn't the -0 ejection charge hamper the forward momentum? Or if the -0 was slipped into a plugged motor mount without much of a retainer, it may help boost the rocket as it is blown out the rear of the rocket...???

I'm liking this idea.

Phil.

Key factor, are the strap ons gonna be ejected or not?

If NOT (meaning they are on pods permanently fixed to the airframe), you have at least three options
1. Big vent hole, so the forward blow of the zero delay engine (not as powerful as a standard ejection charge, but still substantial) has somewhere to go.
2. Plugged engine. Caveat, unless you buy a dedicated plug engine, you can’t use manually plugged motors (fill the front with epoxy) at a club launch because they are “modified.”
3. Motor eject. Loosely friction fit the motor, just enough that it doesn’t fall out due to gravity. Make sure forward end of pod/nose cone of pod is tightly sealed. Motor gets ejected and tumbles back. Works great. Some clubs frown on this, and may restrict it especially when dry conditions in wooded or bushy areas elevate the brushfire risk. This is however the STANDARD recovery technique for common featherweight recovery models like the Mosquito.

If you are going to EJECT the strap ons, you need some sort of release mechanism that will be activated by the zero delay blow forward. Apogee sells a set, browse the forum and you can find some nifty self made techniques.

 

[neil_w]

Given that they are readily available (albeit not from HL), I'd probably use the plugged motors for non-ejecting side boosters, only in conjunction with a larger core motor.

 

[CoachSteve]

I say its completely worth it and fun:

 

[neil_w]

What's that second one?

 

[CoachSteve]

Scratch built 3 motor canted design of my own creation
https://www.rocketryforum.com/threads/canted-3-engine-1-4a-scratch-build.144764/

 

[BABAR]

Scratch built 3 motor canted design of my own creation
https://www.rocketryforum.com/threads/canted-3-engine-1-4a-scratch-build.144764/

Looks like a West Virginia cousin of the Plasma Dart!

 

[Mugs914]

This thread is encouraging... I've been playing with this design for a while, but haven't cut any tubes yet. You guys are quickly becoming peer pressure.

Loosely based on a toy rocket that my brother and I had as kids: