Scott, it's all about having enough thrust at each stage and continued stability. Remember your center of pressure (CP) must be at least one body tube diameter below the center of gravity. Okay, we all know that. Sim the rocket, find the CP, and check where the CG goes after each stage. I've never simmed a staged rocket. Hmmm... the CP is a normally static (doesn't change) measurement, but when you drop a stage, you've just changed CP due to a sudden re-design of the rocket body. Sounds like a fun evening on RockSim. 😉 May take some nose weight. Most I've ever done is three. Unless you do the sim and calculations (yeah, the math) up front, spectators may be dodging stages flying across the prairie! You'll achieve greater stability as it goes up amd drops stages (CG will move toward the nose), but if she's horizontal after the first stage, kinda irrelevant. 😯

Has any one done 5 stages?

Yes. I saw a tiny model rocket that flew four stages of A10's each and then an A3 I think. All I remember was, Pop, Pop, Pop, Pop, and Whoosh. Kind of cute actually.

Doug

Scott, it's all about having enough thrust at each stage and continued stability. Remember your center of pressure (CP) must be at least one body tube diameter below the center of gravity. Okay, we all know that. Sim the rocket, find the CP, and check where the CG goes after each stage. I've never simmed a staged rocket. Hmmm... the CP is a normally static (doesn't change) measurement, but when you drop a stage, you've just changed CP due to a sudden re-design of the rocket body. Sounds like a fun evening on RockSim. 😉 May take some nose weight. Most I've ever done is three. Unless you do the sim and calculations (yeah, the math) up front, spectators may be dodging stages flying across the prairie! You'll achieve greater stability as it goes up amd drops stages (CG will move toward the nose), but if she's horizontal after the first stage, kinda irrelevant. 😯

Bruce
Rock sim will only do 3 stages I think. I will check it out the best I can. I think it will be ok though as I am just adding 1 stage and doubling the length of the Rocket. I think it will still weigh a lot less than that Saturn V I built as a kid and with a lot more fin area too. That Saturn Rocket with a "D" came off the pad like a Fat Man climbing a ladder. 8)

Scott e

Doug - If you ever call one of my projects "cute", I may have to retire from rocketry 😛

The problem I see with doing more and more stages the same as concerns I have when I plan for longburners. If that rocket doesn't go dead straight, by the 3rd, 4th or even 5th stage you have no idea where or what it will be headed at.

Absolutely, the flight I described before was traveling horizontal by the time the last stage went off. It was so small though, no harm, no foul, just cute.

Doug

So I spent a couple of hours on rock sim today. The sim says its stable, and thats with a 50% longer body. The rocket will wiegh in between 11-12 OZ. about 3.5-4 OZ. heavier with the 4th stage and extra 18" of body tube on top. My question is, does an Estas "D-12" have enough push to lift a 12 OZ. rocket. Rocksim seemed to think so. Rocksim thought it was going to wiegh 17 Oz (its 11 or 12) and would fly fine. 🙄 D-12 max thrust is 6.7 LBS with an average of 2.3 what ever thats worth. Max thrust is in the first half second. Is there stronger 24mm moter out there that will light another stage, I couldnt find one. I think it will fly fine, in a calmer wind anyway.

D-12s burn for 1.65 seconds and C-6s burn for 1.86 seconds.
By my calculations (2-Ds and 2-Cs), if something went wrong, we would only have to be Running and Dodging for 7.02 seconds 😉

Answered my own question!!! Found manufacturer recommended max lift off wieght for a D-12 is 396.2 grams (slightly under 14 OZ.)

GOOD TO GO!!!! 8)

I haven't done it, but a SU composite booster should light a BP sustainer, but not the other way around.

I haven't done it, but a SU composite booster should light a BP sustainer, but not the other way around.

But, can you get them without a delay?
I supose with a reloadable you could leave the delay element out and put in a little more powder? 🙄

I thought about this after I wrote it. I was way off.
Im just Using estas "D"s 4 should do it.

Ok so I couldnt help it! I missed the March launch.
So I added a fifth stage. A 4 "D" cluster on the bottom.
1 D12-0 in the middle to light the second single "D" stage.
And 3 D12-3s in pods on the out side. I figure that way the ejections
of the pod moters will not mess with the flight.
Another option would be some big plugged "C"s in the pods.(no ejections)
They burn out at about half the time as the "D"s.
But the dont have as much push to get it off the pad. Hmmmmmmmm 🙄

The final sustainer will return with 3 40 ft. orange streamers. (Um maybe) 😉

I haven't done it, but a SU composite booster should light a BP sustainer, but not the other way around.

But, can you get them without a delay?
I supose with a reloadable you could leave the delay element out and put in a little more powder? 🙄

Since you missed the March launch, you missed the theoretical 7.02sec of dodging you talked about up top...... Plus the BOOM of one of the stages blowing up... I don't remember who gave us the fireworks display and short dodge session, but, it was pretty interesting to say the least.... I think it was a 3 stage w/ "D" cluster on the 1st stage, about a 6' rocket.
Someone else needs to chime in on this one, I was pretty nervous waiting for my L1 cert flight.....

I'd worry about too much air space w/o the delay in the rebuildable - nice boom affect.... Also, wouldn't that just ignite stage 2?

What about just taking some of the delay out with a drill bit???? I had good luck with that on both of my flights this month. I took a 10 sec delay and made it about an 8 sec on one of the launches.