Cluster Power

[Scotty Dog]

OK...Lets say ya got a 18m ,4 motor cluster rocket. It weighs x-amount.To fly it on A8-3s you would need all 4 to work to get the power to launch ..So, would you move up to Bs where 3 or even 2 would get it up in case a motor or 2 fail to ignite ???? Does anyone take this into consideration when dealing with clusters? One more thing, the motors are canted,and Ive heard you have to de-rate the motors?Anywhoo- Hows your weather? Rain

[El Cheapo]

Scott, Q2G2's are great but I've had great success with Estes igniters for 3 and 4 cluster rockets. One failure out of 30+ ain't bad in my mind. Make sure each ignite has a good glob of progen and dump a crap load of power to it.

It's flippin hot here eight now, 111deg

[Scotty Dog]

Scott, Q2G2's are great but I've had great success with Estes igniters for 3 and 4 cluster rockets. One failure out of 30+ ain't bad in my mind. Make sure each ignite has a good glob of progen and dump a crap load of power to it.

It's flippin hot here eight now, 111deg

.But its a DRY HEAT ! I have a 6 pack of Q2s. I bought them for the Deuce. I figure Ill load the 4 banger to test it out(you know the one) and have 2 left for the Duece. Should be an interesting launch, it will be my first cluster(s). Just need the weather and for me to be ready the night before so I can go to the field from work.

[El Cheapo]

Might as well throw it up on B's instead of A's. Heck, go for C's while yer at it. If it's going to fail, might as well fail big.

Pay no attention to the drunken reply above. Sometimes I don't catch the predictive text recommendations on the Droid.

[Rocket_Man]

Scott, Q2G2's are great but I've had great success with Estes igniters for 3 and 4 cluster rockets. One failure out of 30+ ain't bad in my mind. Make sure each ignite has a good glob of progen and dump a crap load of power to it.

It's flippin hot here eight now, 111deg

In Dallas it was near 100 last couple of days, cooled to 95 ??? today.

111 deg at 8pm is sick. this is just June. What happens in August ???

[Shade]

What happens in August ???

Snow?!?

[Zeus-cat]

You do need to derate the motors if they are canted, but the effect is very small. At 10 degrees off vertical the motor still produces 98.5% of the rated thrust straight up. You get 17% of the rated thrust in the horizontal axis.

[El Cheapo]

In Dallas it was near 100 last couple of days, cooled to 95 ??? today.

111 deg at 8pm is sick. this is just June. What happens in August ???

Don't forget the two hour time difference or is it an hour now? I ought know that. I have a bunch of customers in DFW. I could use a good friend in the area. Ever see the movie, Walking Tall?

[MarkII]

I've never heard the phrase "de-rating the motors," and I'm feeling even more ignorant than usual. What does that mean, exactly?

Quest Q2G2s are excellent for clustering. None better. By all means they should be your first choice.

[Micromeister]

Mrcluster says GO for it Scottydog!

if you've designed a cluster to fly on 4 A motors, load it up and fly it. Normally when designing clusters I try to keep the thrust to weight ratio up and take canting into consideration.

Using Q2g2's with 4 motor clusters is almost as easy as flying single motors. I still prefer to use my own Igniters, a relay system with the battery at the launcher but Q2g2's sure gets the odds in your favor as long as your flying from a 12V system of some sort.
Big thing is to pre-test each and every igniter before and after installing in the motors.

[qquake2k]

I always test each igniter separately with a multimeter after I put them in the motors, before I connect all the wires together. I've only used Estes igniters in my clusters, and haven't had a failure yet.

[AlfaBrewer]

.But its a DRY HEAT !

As my brother would say - So's my oven...

Anyhow - I recently had an Art Applewhite cluster saucer have an "interesting" flight profile due to one of the igniters not firing. I was using Estes igniters that I had soldered 8" leads on to eliminate the need for clip whips. Apparently somewhere between soldering and loading the igniters in the motors, one of them snagged something and broke the bridge wire. QQuake's tip of checking them with a ohm meter or using a tester like in a recent Peak of Flight newsletter (last month, IIRC) would have prevented this. Or using the 8" long Q2G2 igniters I had in my box.

I guess the moral here is - clusters are fun, but check the igniters.

[Scotty Dog]

Guess the best thing to do, is get the meter out , make sure I have a good 12v supply and GO FOR IT! Thanks !!!! Ill post pics when it happens.Looks like we are in the RAIN mode for awhile.

[Verna]

OK...Lets say ya got a 18m ,4 motor cluster rocket. It weighs x-amount.To fly it on A8-3s you would need all 4 to work to get the power to launch ..So, would you move up to Bs where 3 or even 2 would get it up in case a motor or 2 fail to ignite ???? Does anyone take this into consideration when dealing with clusters? One more thing, the motors are canted,and Ive heard you have to de-rate the motors?Anywhoo- Hows your weather? Rain

The igniter brand doesn't matter as much as your power supply. We use a car battery.

We are finally getting some beneficial rain after an 8 week drought. The entire state is under a burn ban. I hope Arizona and Texas get some rain to help with the fires too.

Verna
www.vernarockets.com

[El Cheapo]

Rain??? What is that? It's like that mysterious green crap you guys have all over the ground.

What we really need is the ridiculous amount of wind to stop. Looks like our love for careless camp fires is going to keep spreading through "The Land of Enchantment", meet up with the boys in Texas and have one big party.

I may have to alter my morning ritual of drinkin coffee on the front porcch and surfing TRF in muh sleepin pants and flippers to just muh flippers if it gets much hotter

[luke strawwalker]

I've never heard the phrase "de-rating the motors," and I'm feeling even more ignorant than usual. What does that mean, exactly?

Quest Q2G2s are excellent for clustering. None better. By all means they should be your first choice.

I think they're referring to the effect that off-axis thrust is less efficient than axially directionally centered thrust... canting the motors at an angle actually reduces their usable thrust in the form of payload lifting capacity...

That's part of the reason why 'sidemount' rockets like the space shuttle, Shuttle 'C' and other such designs with offset engines producing thrust, canted to run through the vehicle CG, can lift less weight than designs that have the engines directly under the CG... part of the thrust "goes sideways" and is wasted...

Make sense?? The more the motors are canted, the more inefficiency is produced. BUT, canting motors slightly reduces the effects from one engine not lighting as well, so it's a tradeoff...

Later! OL JR

[luke strawwalker]

Rain??? What is that? It's like that mysterious green crap you guys have all over the ground.

What we really need is the ridiculous amount of wind to stop. Looks like our love for careless camp fires is going to keep spreading through "The Land of Enchantment", meet up with the boys in Texas and have one big party.

I may have to alter my morning ritual of drinkin coffee on the front porcch and surfing TRF in muh sleepin pants and flippers to just muh flippers if it gets much hotter

Didn't need THAT picture in my head...

Thanks so much for that...

later! OL JR

[bjphoenix]

Don't forget the two hour time difference or is it an hour now? I ought know that. I have a bunch of customers in DFW. I could use a good friend in the area. Ever see the movie, Walking Tall?

The time difference depends on the time of year- daylight savings time vs. non daylight savings time. In the winter it is 1 hour different, IIRC 2 hours in summer.

There are lots of us in the DFW area.

I've flown 2-engine and 3-engine clusters for a long time, my first was in about 1968 (see post #2 in this thread):
http://www.rocketryforum.com/showthread.php?p=171239

I've never had a problem with all 3 igniting, when using a 12V car battery. If I was flying 4 and needed all 4 A's to fly the rocket, I would switch to B's.

[FastCargo]

Yep, definitely use a 12V battery, esp something like a car or motorcycle battery. Works great on clusters. And modifying a standard Estes controller to use such a thing is a snap. I modified one a LONG time ago with lamp and speaker wire and I'm electrically impaired...

One thing to caution you on is replace the standard continuity bulb with something like these:

http://www.pinballlife.com/index.php...174&parent=192

They have a higher resistance, so a continuity test on a 12V system won't launch (especially important for Quest G2 ignitors), and they are 6 and 12 volt compatible, so they won't burn out like the standard bulb will if used repeatedly on a 12V system.

Thanks to shreadvector for the original tip.

Also, I'm a 'low show' kind of guy...I'd rather use smaller engines in clusters because it makes for a better show, while still keeping the rocket in the general area...

FC

[plano-doug]

If I was flying 4 and needed all 4 A's to fly the rocket, I would switch to B's.

Yes.

I have one rocket which stages 3x18mm to 3x18mm. With a rocket that large, and three sustainer motors, it doesn't tolerate a one-out boost off the pad I've put it back together twice now after two such launches with unpleasant outcomes.

And I've gotten better at prepping clusters

Doug

.

[Scotty Dog]

Yep, definitely use a 12V battery, esp something like a car or motorcycle battery. Works great on clusters. And modifying a standard Estes controller to use such a thing is a snap. I modified one a LONG time ago with lamp and speaker wire and I'm electrically impaired...

One thing to caution you on is replace the standard continuity bulb with something like these:

http://www.pinballlife.com/index.php...174&parent=192

They have a higher resistance, so a continuity test on a 12V system won't launch (especially important for Quest G2 ignitors), and they are 6 and 12 volt compatible, so they won't burn out like the standard bulb will if used repeatedly on a 12V system.

Thanks to shreadvector for the original tip.

Also, I'm a 'low show' kind of guy...I'd rather use smaller engines in clusters because it makes for a better show, while still keeping the rocket in the general area...

FC

Low n Slow Fat Bottomed Rockets......Heaven

[Verna]

Low n Slow Fat Bottomed Rockets......Heaven

Low & slow rules!



Verna
www.vernarockets.com