tg08
Well-Known Member
I'm planning on clustering 2 F Aerotech motors, does anyone have experience with this? The Firstfire's that are included say that they are not recommended for clustering motors.
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Watching this thread closely, I’m just as curious as you are.
One thing I do know if that you want to choose your propellants carefully. Blue Thunder, for example, is pretty easy to ignite and it generates enough thrust that you can get a safe rod clearance speed on one motor without too much trouble. Ejection might be dicey though…
Smokey propellants, on the other hand, have a bunch of crap in the propellant that doesn’t burn (hence the smoke), meaning they’re trickier to ignite. Some varieties of White Lightning oxidize as well and will typically benefit from some scuffing up.
As far as the ignition system goes, I’d say current is your friend (to a point), but I don’t really know anything about suitable igniters.
tg08
Well-Known Member
Thanks. I'm planning on using my last 2 Redline motors, which (in my experience) have a very high ignition rate, but they like to give a little show before they come up to thrust. I'm only a little worried, as they should ignite within a fraction of a second if ignition is right. Not too worried about ejection either, I'm probably using electronic deploy.
FastJack or Blue Thunder lite by Firewire matches dipped in QuickBurst Mix to make sure they both come to pressure at the same time would be what I would do.
How old are the Redlines?
tg08
Well-Known Member
Only 2 months old, they became obsolete after I converted my rocket to dual deploy.
Well then they have not degraded with years of age, use the Firewire starters you can get from Chris Supplies in a nice pack and dip them. DO you have anyone in your club or who you know may have dip?
Otherwise you have to add the cost of dip
That is pretty pricy, 14gms is $22 here: https://quickburst.net/qb/new-and-improved-quickburst-quickdip-kit/
I though I saw a 7gms bottle last month but cannot find it.
Make sure to verify that your Nozzle in the motor is large enough to pass the firewire head. If not you might need the MJG BP starter and dip it.
Firewire head size:
The BP starters will fit in Estes 18mm motor:
The BP starters will fit in Estes 18mm motor:
If you Dipped them , they would work and not need the matches
tg08
Well-Known Member
Woah, Apogee offers 28 grams for $50 as opposed to $38. Great company, but sometimes markups can be insane.
tg08
Well-Known Member
Ok thanks, I'll just do that instead.
Yea, the reason for matches is the chance of a bad match vs bad made pyro starter is much less, and less to damage on them if mishandled.
waltr
Well-Known Member
Will the rocket fly SAFELY on one motor?
tg08
Well-Known Member
According to the sim, yes. However, I would need to test again once it's built(very distant future) and all the weight is totaled up.
To cluster Aerotech hobbyline E & F motors, I use MJG black powder starters dipped in Quickburst Procast (BKNO3). So far I have only used these on Blue Thunder in actual flights. I have ground-tested (but not yet flown) this combination on Quest E35 motors which are White Lightening. Will probably fly the E35s in a three-motor cluster later this month.
One time I used two 24 mm Aerotech motors on my Double Shuttle and it worked. The second time only one fired. Going back and looking at the photos, I can see one motor fired before the other with the second motor firing as it went up the guide rail. So, I am not sure how reliable this method is. Having long lead wires on the igniters helps, because if one motor fires, the igniter stays in the other motor and has a chance to fire.
Yes, I use the 3' lead version of the MJGs and tape the leads high up the rail, so there is probably nearly 5 feet of travel before any un-ejected starters are pulled out of motors that are slow to pressurize.
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Ive had good luck with Davey fire matches.
Rocketjunkie
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I fly a lot of clusters, ranging from Rx 18 mm D grains to 98 mm Rx or commercial. If they will fit the nozzle, the MJG BP starters, dipped in QuickBurst ProCast is your best option. They require less than 1A to fire and are reliable. Secure each one to the motor it's inserted into. I masking tape to the motor or side of the rocket. Do not cover the nozzle. Tiny starters for tiny motors (Q-Jet B4) I have to make. I have photos of making the starters shown here. For big motors that I have to start **now** I use copper thermite. I also make flights that will be safe on the central motor and fuse the rest. Message me if you want more details.
If the F motors have a long delay or adjustable, they can act as a secondary or tertiary backup in a DD setup.
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Quickburst is the company. Quickdip is one of their products. What you want is the Procast dip, which burns 3-4x hotter than their other formulations. Buy from them, not anyone else (like Apogee).
https://quickburst.net/qb/procast-order-page/
If you really want to make sure you get them lit (and Redlines aren't the easiest to light), use Procast to dip your igniter (or a good e-match) and add a small sliver of Blue Thunder to the end of the igniter (as long as it will fit into the nozzle throat). Aerotech 18mm D14T reloads are good for this. Igniter lights the Procast, Procast ignites the Blue Thunder, Blue Thunder lights the motor. Whoosh!
