Questions on 'makeshift' 3 stage rocket + engine differences...

Questions on 'makeshift' 3 stage rocket + engine differences...

Post by Jame » Sat, 09 Jan 1999 04:00:00



Hey,

I've been into rocketry for about 4 years now, but have only ever really
had the chance to make 1+2 stage rockets... I just have a few questions...

I had two 2 stage rockets that were identical, and I lost the main second
stage rocket part of one, leaving me with just the booster stage.

Is it possible for me to use the now 'spare' booster stage with my other
complete 2 stage rocket, to make it 3 stage?

If so, what would I use in each compartment, engine wise:  C6-0, Upper
engine , Upper engine?

Also, what is unique about the upper stage engines that differs them from
the other types? Nozzle size? Please explain :)

I was advised to use a C6-0 in the booster stage... why is this? Could I
still use a C6-3/5? Surely the ejection phase is the same [except the
timing]?

Cheers,

James

--
Stuff Danofram

 
 
 

Questions on 'makeshift' 3 stage rocket + engine differences...

Post by J. Steven Yo » Sat, 09 Jan 1999 04:00:00


Quote:

>Hey,

>I've been into rocketry for about 4 years now, but have only ever really
>had the chance to make 1+2 stage rockets... I just have a few questions...

>I had two 2 stage rockets that were identical, and I lost the main second
>stage rocket part of one, leaving me with just the booster stage.

>Is it possible for me to use the now 'spare' booster stage with my other
>complete 2 stage rocket, to make it 3 stage?

Depends first on how the engine mounts in the boosters are
constructed.  If they don't plug together properly, with engines in
place, then you're SOL.  Even if they do fit, the combination may not
be stable without further modifications (enlarging the fins on the
lower booster, adding nose weight, lengthening the upper stage.

Quote:

>If so, what would I use in each compartment, engine wise:  C6-0, Upper
>engine , Upper engine?

Always use a booster (zero delay) engine in the two lower stages.
More on this later.  Choice of engines will depend on weight (the
first stage has to lift both itself, the two upper stages, and the two
engines) and the altitude you hope to obtain.  Use a long delay engine
in the upper stage.  Rocketry simulation software such as Rocketsim or
RASP is useful in figuring out the proper engines, but you can probaby
"eyeball" it based on the original engines recommended for the model,
and for similar three stage models (if there are any).

Quote:

>Also, what is unique about the upper stage engines that differs them from
>the other types? Nozzle size? Please explain :)

Upper stage engine differ only in that they have a long delay charge.
They work just fine in light-weight single stage models as well.
Since a two or three stage rocket will go faster than a single stage
model with the same thrust (as the upper stage motor alone) then it
needs to allow for a longer coast time before deploying the engine.
The nozzles and propellent for a given type of engine (say, C6-0,
C6-3, C6-5, C6-7) are all the same.  Only the delay and ejection
charges (or lack of same) differ.

Quote:

>I was advised to use a C6-0 in the booster stage... why is this? Could I
>still use a C6-3/5? Surely the ejection phase is the same [except the
>timing]?

Those "zero" delay engines DO differ significantly from convention
engines.  They have no delay charge (and no tracking smoke), no
ejection charge, and no clay cap at the end.  As the propellent burns
through to the exposed end it simply bursts through the thin remaining
shell, sending chunks of burning propellent shooting out the front of
the engine casing.  It is these chunks of propellent that travel into
the nozzle of the next stage engine and ignite it.  The ejection
charge of a conventional single stage or upper stage engine MIGHT also
ignite the next motor in sequence, but by that time, the rocket will
have arched over.  At best, it will take the rocket off at an angle.
At worst, it will ignite the next stage with the rocket aimed back
toward the ground, possibly a very dangerous proposition.

So, anything except the top stage of a stack MUST have a booster (zero
delay) motor.  The top stage needs a long enough delay to allow for
extra coasting time caused by the booster(s).  Usually this means an
"upper stage" motor.  But a light, low-drag, single stage may also fly
just fine on that "upper stage" motor, and a heavy, high-drag
multistage may still use a "single stage" delay like a C6-5, B6-4, or
D12-5.

 
 
 

Questions on 'makeshift' 3 stage rocket + engine differences...

Post by Jame » Sun, 10 Jan 1999 04:00:00


Thanks, everything is MUCH clearer now!! I'll notify you with my progress :)

Cheers,

James


Quote:


> >Hey,

> >I've been into rocketry for about 4 years now, but have only ever really
> >had the chance to make 1+2 stage rockets... I just have a few questions...

> >I had two 2 stage rockets that were identical, and I lost the main second
> >stage rocket part of one, leaving me with just the booster stage.

> >Is it possible for me to use the now 'spare' booster stage with my other
> >complete 2 stage rocket, to make it 3 stage?

> Depends first on how the engine mounts in the boosters are
> constructed.  If they don't plug together properly, with engines in
> place, then you're SOL.  Even if they do fit, the combination may not
> be stable without further modifications (enlarging the fins on the
> lower booster, adding nose weight, lengthening the upper stage.

> >If so, what would I use in each compartment, engine wise:  C6-0, Upper
> >engine , Upper engine?

> Always use a booster (zero delay) engine in the two lower stages.
> More on this later.  Choice of engines will depend on weight (the
> first stage has to lift both itself, the two upper stages, and the two
> engines) and the altitude you hope to obtain.  Use a long delay engine
> in the upper stage.  Rocketry simulation software such as Rocketsim or
> RASP is useful in figuring out the proper engines, but you can probaby
> "eyeball" it based on the original engines recommended for the model,
> and for similar three stage models (if there are any).

> >Also, what is unique about the upper stage engines that differs them from
> >the other types? Nozzle size? Please explain :)

> Upper stage engine differ only in that they have a long delay charge.
> They work just fine in light-weight single stage models as well.
> Since a two or three stage rocket will go faster than a single stage
> model with the same thrust (as the upper stage motor alone) then it
> needs to allow for a longer coast time before deploying the engine.
> The nozzles and propellent for a given type of engine (say, C6-0,
> C6-3, C6-5, C6-7) are all the same.  Only the delay and ejection
> charges (or lack of same) differ.

> >I was advised to use a C6-0 in the booster stage... why is this? Could I
> >still use a C6-3/5? Surely the ejection phase is the same [except the
> >timing]?

> Those "zero" delay engines DO differ significantly from convention
> engines.  They have no delay charge (and no tracking smoke), no
> ejection charge, and no clay cap at the end.  As the propellent burns
> through to the exposed end it simply bursts through the thin remaining
> shell, sending chunks of burning propellent shooting out the front of
> the engine casing.  It is these chunks of propellent that travel into
> the nozzle of the next stage engine and ignite it.  The ejection
> charge of a conventional single stage or upper stage engine MIGHT also
> ignite the next motor in sequence, but by that time, the rocket will
> have arched over.  At best, it will take the rocket off at an angle.
> At worst, it will ignite the next stage with the rocket aimed back
> toward the ground, possibly a very dangerous proposition.

> So, anything except the top stage of a stack MUST have a booster (zero
> delay) motor.  The top stage needs a long enough delay to allow for
> extra coasting time caused by the booster(s).  Usually this means an
> "upper stage" motor.  But a light, low-drag, single stage may also fly
> just fine on that "upper stage" motor, and a heavy, high-drag
> multistage may still use a "single stage" delay like a C6-5, B6-4, or
> D12-5.

--
Stuff Danofram