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For rockets using the Estes-type (Black Powder) engines, one usually tapes the various stages' motors together (end-to-end). That way, the hot gases blowing through the booster's engine enters directly into the nozzle of the second stage's engine. Use Scotch Magic Transparent Tape (not masking tape), since it melts faster when the second stage ignites. and isn't thick.
If you want to use an existing single-stage rocket and make it able to handle a second stage, just make a booster stage. Your existing rocket will now be the "second stage," or "sustainer." The new booster stage that you'll make has no thrust ring, and it should be the same length as your booster engine. If you want to use an Estes E-impulse engine, you'll have to make the booster body tube longer than for A-D engines.
Make some large fins for your booster, and line them up directly underneath the sustainer's (2nd stage) fins. That way, you'll have good aerodynamics.
Select a zero-delay engine for your booster, such as a C6-0 or D12-0. As soon as the booster stops thrusting, it will "blow through" into the nozzle of the 2nd stage. The 2nd stage (sustainer) will ignite quickly, and the booster will tumble back to the earth. You don't need a parachute or streamer for the booster.
If you want to use an existing single-stage rocket and make it able to handle a second stage, just make a booster stage. Your existing rocket will now be the "second stage," or "sustainer." The new booster stage that you'll make has no thrust ring, and it should be the same length as your booster engine. If you want to use an Estes E-impulse engine, you'll have to make the booster body tube longer than for A-D engines.
Make some large fins for your booster, and line them up directly underneath the sustainer's (2nd stage) fins. That way, you'll have good aerodynamics.
Select a zero-delay engine for your booster, such as a C6-0 or D12-0. As soon as the booster stops thrusting, it will "blow through" into the nozzle of the 2nd stage. The 2nd stage (sustainer) will ignite quickly, and the booster will tumble back to the earth. You don't need a parachute or streamer for the booster.
eugenefl
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Dluders is right on track with the suggestions on adding a booster stage.
One crucial piece that was forgotten was the fact that attention to your CG/CP relationship still has to be made. With an added booster, you're moving the CG towards the rear. Of course, the new fins enhance the CP, but care needs to be taken to ensure stability is still maintained. This is usually solved by adding nose weight.
As far as construction goes, you can use a tube coupler to be used as your stage coupler. A short length of body tube can be used to match the upper stage. When building the sustainer, or upper stage, an engine hook is usually omitted.
So what are you planning on adding a second stage to?
One crucial piece that was forgotten was the fact that attention to your CG/CP relationship still has to be made. With an added booster, you're moving the CG towards the rear. Of course, the new fins enhance the CP, but care needs to be taken to ensure stability is still maintained. This is usually solved by adding nose weight.
As far as construction goes, you can use a tube coupler to be used as your stage coupler. A short length of body tube can be used to match the upper stage. When building the sustainer, or upper stage, an engine hook is usually omitted.
So what are you planning on adding a second stage to?
firemanup
Well-Known Member
From Harry Stine's book reference lining up the fins from two stages...
"To achieve maximum possible stability during boost, don't align the fins of the various stages in a fore and aft direction. This puts the lower stage fins in the wake, downwash, and vortex pattern of the upper stage fins and greatly reduces their effectiveness. You need all the effectiveness you can get from the lower stage fins. Instead, interdigitate the fins. Put them out of line with one another as shown in Figure 11-8"
Figure 11-8 just shows the fins not being lined up but rather the lower stage fins splitting the difference between the upper stage fins.
Food for thought.
Jason
"To achieve maximum possible stability during boost, don't align the fins of the various stages in a fore and aft direction. This puts the lower stage fins in the wake, downwash, and vortex pattern of the upper stage fins and greatly reduces their effectiveness. You need all the effectiveness you can get from the lower stage fins. Instead, interdigitate the fins. Put them out of line with one another as shown in Figure 11-8"
Figure 11-8 just shows the fins not being lined up but rather the lower stage fins splitting the difference between the upper stage fins.
Food for thought.
Jason
What is a thrust ring?? I am realtively new to modding rockets although I probably know what this piece is, just not the jargon. How does the actual booster (not booster engine) attatch to the sustainer? Can someone please post a closeup pic? So to make a booster all I need is to get piece of larger size body tube than the sustainer and install an engine mount and fins?
The "thrust ring" is that little green ring made of thick cardboard. It would fit over your pinky. It glues inside the Motor Mount Tube (MMT) so that the motor has a "push block" to thrust against. You don't need a thrust ring in most low-power rockets; the "friction fit" method (using masking tape) works fine.
Your booster will connect to the 2nd Stage (your existing rocket) via the Scotch Magic Transparent Tape holding your motors together (end-to-end). You won't be able to use an "engine hook" clip on your original rocket, though. If it has one, you'll have to cut it off so that it doesn't interfere with the booster mating up to the sustainer.
Both the 2nd Stage's motor, and the Booster's motor, will be "friction fitted" to their body tubes using masking tape. The tape will keep the motors from ejecting backwards, and leaving the rest of the rocket behind. You want a pretty tight fit; add more (or less) masking tape until you're sure that the motor would not leave the booster or sustainer upon motor ejection.
To assemble the motors on a 2-stage rocket, tape the motors together (being careful that all motor nozzles face DOWN). Then, add masking tape to the sustainer's motor, and friction-fit it to the sustainer. Then, add masking tape to the booster's motor, and push on the Booster Stage.
Believe it or not, the only thing holding your booster and sustainer together is the Scotch Magic Transparent Tape. It works great!
Your booster will connect to the 2nd Stage (your existing rocket) via the Scotch Magic Transparent Tape holding your motors together (end-to-end). You won't be able to use an "engine hook" clip on your original rocket, though. If it has one, you'll have to cut it off so that it doesn't interfere with the booster mating up to the sustainer.
Both the 2nd Stage's motor, and the Booster's motor, will be "friction fitted" to their body tubes using masking tape. The tape will keep the motors from ejecting backwards, and leaving the rest of the rocket behind. You want a pretty tight fit; add more (or less) masking tape until you're sure that the motor would not leave the booster or sustainer upon motor ejection.
To assemble the motors on a 2-stage rocket, tape the motors together (being careful that all motor nozzles face DOWN). Then, add masking tape to the sustainer's motor, and friction-fit it to the sustainer. Then, add masking tape to the booster's motor, and push on the Booster Stage.
Believe it or not, the only thing holding your booster and sustainer together is the Scotch Magic Transparent Tape. It works great!
Check out the web site https://www.apogeerockets.com/education/how_to_multi-stage.asp for an article about "How Multi-Stage Model Rockets Work." It is a free item from Apogee Components. The pictures will explain a lot.
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