Challenge is good.
Clusters are cool.
My motto? "Cluster's rule, mono's drool"
If you understand clustering, take your time and follow some simple rules, clusters are not difficult, nor are they unreliable. My success rate on clusters is about one failure out of every 300-500 cluster launches and anybody can match that rate easily.
If you purchase a cluster kit from FlisKits you will get a short hints and tips sheet on clustering which will answer most of your questions. Don't want to buy any of our kits? No problem, just send me an email and I'll get the sheet off to you.
If you are going with a BT-70 tube, I would recommend a three motor 24mm cluster. You can do this scratch building easily and/or purchase an engine mount kit for the job (FlisKits has 2 versions of this very kit in stock)
Using such a cluster would allow you to fly with C11, D12 or E9 motors for some fantastic flights, easily lifting your payload. Your only concern (after motor ignition) is selecting the proper delay charge depending on the mass of your rocket at liftoff. Our
Richter Recker , for example, at nearly 16oz liftoff weight on D12 motors uses a 5 second delay charge.
To be successful with clusters, follow these simple rules with each and every flight:
- Using standard ignitors that come with the motors, match them up for size and shape (They don't need to be big (lots of pyro) or small, just similar in size)
- Do a continuity check on each ignitor before using
- If uncertain, gently scrape the fuel area inside the nozzle to remove any foriegn residue
- CAREFULLy install each ignitor making sure the tip of the ignitor touches the fuel inside the motor then use the provided plug or a ball of recovery wadding to hold in place.
- Plug the top of each motor with a small ball of recovery wadding held in place with tape. In the event of a misfire on one motor, this will prevent the other motor from igniting *this* motor in reverse when the ejection charge goes off.
- If applicable, twist the leads together tightly or use a clean clip whip to hook up all the ignitors
- NOTE: CRITICAL: Always hook your ignitors up in PARALLEL, never in series
- NOTE: CRITICAL: Always use a good strong power source. My recommendation is to use a car battery or equivilant. If you are using club equipment with LONG leads, make sure they use a "Relay System".
That's it. It sounds involved, but really you should perform pretty much these same steps for every launch, cluster or not, so as to not waste ignitors and time.
Keep watch over FlisKits before the end of the year for 2 clusters models (3 18mm and 3 24mm) coming out soon
jim