2 Stage Rocket questions....

Recently I put together my first 2 stage rocket. (Express by Estes.)
There are three parts listed with different engines.
1st Stage.
2nd Stage or Booster
Upper
Which one is 1st Stage and Booster? (I'm guessing "Upper" is the piece with the nose cone.)

Also, there are various engines listed for 1st and 2nd stage.
1st has: C11-5 and D12-0
2nd: C11-0 and D12-0
Does it make a difference to match up the numbers in sequential order only or can I mix them?
Does it need to be C11-5 with C11-0 or could I do C11-5 with D12-0?

The first stage is the booster, which is the first motor lit (on the ground). The second (or sustainer) is airstarted.

Not understanding your second question. If you are asking if you can put a C11-5 in the booster and a C11-0 in the sustainer, then NO!!! NO!!! NO!!!

The sustainer or upper stage is the nose cone, the booster or lower stage is the bottom section.

As blackbrant said, don't put a ?x-0 motor in the sustainer. The -0 motors go in the booster and are lit on the pad.

Yes, you can use any -0 motor in your booster without regard for what is in the sustainer. A B6-0, C6-0, C11-0 or D12-0 will lite any of the sustainer motors like B6-6, C6-7, D12-7, etc. The concern is whether the booster motor has enough thrust to lift the rocket with the sustainer motor. I made a new booster for one of my rockets with a 24mm MMT so I could use a D12-0 booster motor. The C6-0 didn't have enough thrust for my taste.

Make sure whatever booster (first) motor you use, can lift the weight of the entire rocket, AND the sustainer motor (second stage) AND the Booster (first motor).

A B6-0 to a D12 could be a bad day. I'd tend toward using a larger motor as the booster. But as Handeman said, it can be done as long as you check to max liftoff weights.

DizWolf said:

Make sure whatever booster (first) motor you use, can lift the weight of the entire rocket, AND the sustainer motor (second stage) AND the Booster (first motor).

A B6-0 to a D12 could be a bad day. I'd tend toward using a larger motor as the booster. But as Handeman said, it can be done as long as you check to max liftoff weights.

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So if I was to go only by the recommended engines in the instructions, which I'd rather do, go with the max of D12-0 in booster/2nd stage and C11-5 or D12-5 for sustainer/1st stage?

LaunchPad said:

So if I was to go only by the recommended engines in the instructions, which I'd rather do, go with the max of D12-0 in booster/2nd stage and C11-5 or D12-5 for sustainer/1st stage?

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Yes, but booster is called 1st stage and sustainer is called 2nd stage.

That CC express flies really high - just about out-of sight on D engines.

For your first flight I would suggest using the Estes (Standard/D) Adapter and fly it Single Stage on a B6-4 engine.

Try it Single Stage on a C11-5 before you try flying it with both stages.

Get at least two people to watch the two stage flight - make sure one person watches the lower stage when it tumbles/falls to the ground. If nobody is watching - that piece is easy to loose.

Not a bad idea to go single stage for first flight

First 2-STAGE flight go with the C11-0 booster and C11-5 sustainer. You will get to see the staging better and are more likely to recover both sections.
Going up to D12-0 in booster will increase the altitude of the staging, and putting a d12-7 in upper stage may but ejection out of visual range (whether you put a C or D in the booster).
What are your flight goals? Going really "high" sounds cool, but you won't see the upper part of the flight well (out or nearly out of visual range) and if there is a little wind you are looking at a long walk and if there is a lot of wind you may be saying bye bye to the rocket. On a windless day though a D to D is a good choice to try at least once.

LaunchPad said:

So if I was to go only by the recommended engines in the instructions, which I'd rather do, go with the max of D12-0 in booster/2nd stage and C11-5 or D12-5 for sustainer/1st stage?

Click to expand...

Yes... depending on the size of the field and the conditions at launch, and the size/expected altitude of the rocket...

The first stage (booster) motor generally needs to be bigger, because it's lifting the weight of the first stage and the motor itself, but also the upper stage and ITS motor, plus the recovery device, and any payload (if applicable). All this extra weight (particularly of the upper stage motor, which is usually the heaviest component) plus the extra drag created by the upper stage fins and airframe means the first stage booster motor must have a pretty good 'kick' to get the rocket up and moving off the pad and accelerated to a sufficient velocity to 1) be stable by the time it leaves the launch rod (accelerated to approximately 30 mph) and 2) have sufficient airspeed and altitude to remain pointed upright and stable during the short interval (usually part of a second) for the first stage motor to burn out and the upper stage (sustainer) motor to actually ignite, come up to pressure, and separate the stages and continue accelerating the upper sustainer stage away from the booster during the continuation of the flight.

Since the rocket is already up and moving at a considerable velocity at staging, the velocity of the first stage adds to the velocity imparted by the upper sustainer stage's motor, so the rocket reaches a considerably higher altitude than it would with the same motor lifting the upper sustainer stage from a standstill off the pad... The higher the altitude, the more drift one can expect during the recovery phase due to wind, and therefore the farther downrange the rocket will travel before landing. Therefore, you need to be aware of 1) the flying conditions when you're launching (high winds and high altitudes= lost rockets a lot of times) and 2) the size/surroundings of the launch field. Using a smaller upper sustainer stage motor will reduce the maximum altitude the rocket achieves and thus should keep the rocket landing closer to the launch site, and hopefully within the flying field. If you have high winds on the day your launching, or your flying site is surrounded by rocket-eating trees, neighborhoods, water, other private property that might make recovery difficult or impossible if it lands off-field, etc. then you want to choose the smallest recommended motors for the booster first stage and sustainer second stage that the instructions recommend. If it's a calm day, flying from a LARGE field with plenty of safe, open, downrange recovery area for the rocket's upper sustainer stage to land in, and you want to go for the absolute maximum altitude/performance the rocket can achieve, then go for it and use the largest recommended motors!

Later and hope this helps...

OL JR