Cluster 2 stage flying saucer

[rockets]

Never flown a 2 stage, never flown a cluster. But, I'm hoping to do both and in style!! How about, a cluster 2 stage flying saucer.
And I think this would be fun; 4 A10's staging to 4 A10's. AND....No electronics needed. At my HL, they have A10-0, A10-PT, and A10-3T, on sale & clearance.
Once I get some experience with this rocket, I can scale up to MPR.
What do you guys think?

Thanks,

 

[Daddyisabar]

Not a good idea for your first staged, clustered rocket. Go build an Estes MIRV, they are on clearance at Hobbylinc.com. Fly it a few times. Then try something like this in a scratch build:



Then try what you are thinking of out on the high power pads and with a little luck it might work.

 

[GlenP]

or scratch build this from the plans:
http://plans.rocketshoppe.com/srw/srwMG/srwMG.htm
Seattle Rocket Works: MIRV Gryphon

Estes MIRV is a good suggestion, only one booster motor lights the three sustainers, but that does not really give you the option of a cluster ignition off the pad.

First experience learning is best done with a proven design.

 

[rockets]

Not a good idea for your first staged, clustered rocket. Go build an Estes MIRV, they are on clearance at Hobbylinc.com. Fly it a few times. Then try something like this in a scratch build:

View attachment 325757View attachment 325758View attachment 325759

Then try what you are thinking of out on the high power pads and with a little luck it might work.

I'm not flying this as HPR, not even MPR, just trying it at very low power, mini A motors. The Mirv looks interesting, may have to look into that.

Thanks,

 

[Daddyisabar]

I'm not flying this as HPR, not even MPR, just trying it at very low power, mini A motors. The Mirv looks interesting, may have to look into that.

Thanks,

When you show up with a 4 to 4 staged, clustered saucer, it is a very complex and highly questionable rocket. All four A motors will have to light and stage at the same time. Therefore you will be sent to the far far away pads for good reason. Your little A powered rocket will put the SCARE into any RSO, so you will be out at the big boy pads. The A 10 is an excellent motor to stage due to the large nozzle. This is not so for larger BP motors. So a C or D version will really put the SCARE into the RSO. If you get a pad assignment with those little LPR motors you might be out with the TOP MEN, flying your C6's next to the research loads with letters on the back side of the alphabet! Be ready for top man questions like "Where is your CP?" "Where is your sim?" "How are they all going to light at the same time and stage nice and straight?" "If they don't, how far is it going to fly?"

What if three motors light, it angles off the pad and then three more motors stage? What if all four light on the first stage but only two in the second stage light? What happens if one motor in the first stage CATOS? It is enough to send a grown man back to the car with tears in his eyes, having to throw a tantrum that no Capri Sun juice box can ease.

Yes, start with the MIRV and work up to clustering and staging scratch built rockets.

 

[Daddyisabar]

And the MIRV is really cool. You can tell your friends that you have built a flying launch pad. The three rockets in the upper stage are intentionally UNSTABLE! They are ignited by split and ducted gasses from the tumble recovery first stage.

 

[rstaff3]

I flew my MIRV exactly once. The booster and one sustainer got eaten by the soybeans. The latter eventually reappeared. I then flew the three sustainers off a single rod.

 

[rstaff3]

Not a good idea for your first staged, clustered rocket. Go build an Estes MIRV, they are on clearance at Hobbylinc.com. Fly it a few times. Then try something like this in a scratch build:

View attachment 325757View attachment 325758View attachment 325759

Then try what you are thinking of out on the high power pads and with a little luck it might work.

I LIKE this!

 

[Charles_McG]

Something that you may not appreciate is how the motor burn times can vary, even in the same motor type. The NAR certification page (from the NAR website) lists the burn time for A10-0Ts as a mean 1.06 sec with a standard deviation of 0.05 sec. Rough rules of thumb suggest that about 1/3 would fall -outside- 1.01 to 1.11 sec and 1/20 outside 0.96 to 1.16 sec.

So even if you get all 4 1st stage motors to light together, if you 1-to-1 stage all motors, the second stage is almost guaranteed not to light together.

That's why clustered multistage are designed so the first motor to burn through lights -all- the next stage. And that ends up looking like a 3 to 1 or a 1 to 3 (like the MIRV). I have a down scale Little Beth X2. (From JimZ's rocket plans) that is 3-to-1 - but only the center motor stages. The other two are outboard pods.

And I also, have made the Long Walk out to the high power pads because the RSO raised a high eyebrow at my little rocket - first flight of a fiberglass V2 in my case.

Daddy, that fire arrow is awesome. It doesn't look like you put any spin on it - does it get squirrelly as it stages unevenly? Or is the weight so far forward it doesn't matter?

 

[Daddyisabar]

Daddy, that fire arrow is awesome. It doesn't look like you put any spin on it - does it get squirrelly as it stages unevenly? Or is the weight so far forward it doesn't matter?

Fire Arrow is a great name for that rocket. I called it "Here, hold my beer, I'm a gonna fly me a Sharknader!" Being a silly tractored motored rocket most of the "sin" is greatly reduced once all four booster motors light and it rips off the pad. When I flew it one of the booster motors CATOED. As it lifted up the igniter wire caught on the fin so it pulled the lead cord out of the electrical box and took it for a ride. The CATOED booster motor lit the second stage motor in its column so the timing was off. That second stage motor then blew off with the CATOED casing still attached. It was raining spent A-10 cases everywhere. The CATO column ejected early, but since it was nose blow recovery, even that did not have a significant effect as it was still headed up with plenty of inertia.



[video=youtube;-LGE35G-lYY]https://www.youtube.com/watch?v=-LGE35G-lYY[/video]

Good thing I was able to tell the RSO what would happen on a CATO before the launch and it actually worked. Love that mindsim!

 

[Charles_McG]

That's great. I haven't seen a black powder CATO split a casing like that. Mine have either spit the nozzle aft, or the fuel grain forward.

 

[Daddyisabar]

That's great. I haven't seen a black powder CATO split a casing like that. Mine have either spit the nozzle aft, or the fuel grain forward.

That is because it was an A-10-0 tightly taped to another motor on top. The CATO blew out the nozzle,ripped open the case and lit the second stage motor. The case then acted like an extended combustion chamber as the Scotch tape held firm. The split case must have negated any Krushnic effect. Then the two motors ejected off in the out of sequence stage, one of the many chunks flying off in the video.

Power and nose weight do not solve all yer problems, but knocking 95% of them off the top ain't bad!

 

[neil_w]

It was raining spent A-10 cases everywhere.

I LOLed.

Is it just me or is that video only Youtube only 240p? Unless it was transcoded it through a 1980 VHS player I'm not sure how you could even get such a low-res video anymore.

 

[Daddyisabar]

I LOLed.

Is it just me or is that video only Youtube only 240p? Unless it was transcoded it through a 1980 VHS player I'm not sure how you could even get such a low-res video anymore.

I took the vid with my Fancy Phone so who knows what this old dude screwed up? Maybe Youtube downgraded because they though this old guy will think VHS quality is cool

Cluster staging Cheap and Dirty 4 to 4 to 4 and you are guaranteed lots of junk falling back to earth.

 

[Micromeister]

I've been flying 2 & 3 stage UFO's for decades. But NOT clustered. Simply D12-0, C6-0, or D12-0, C6-0, A10-3

If you intend to multi-Stage cluster it is imperative that a Relay Ignition system be used, Match by weight all motors in each stage as closely as possible. As previously noted all BP motors have a 5% +/- variable built-in so all upper stage ignition will be somewhat a crap shoot. I'd strongly suggest going with a clustered first stage to a single motor upper stage for safety sake.