Stovi modifications

Stovi modifications

Post by -Wiersbe,R. » Tue, 24 Mar 1998 04:00:00



I picked up a LOC Stovi over the weekend and would like to know if anyone
out there has modified this kit for clusters. The instructions have the
nice disclaimer "LOC does not recommend using motors in the outboard tubes" (or
something like that).

For those of you not familiar with the kit, it's 3" diameter at the bottom,
with a transition to 2.2" at the payload. There are seven 24mm motor tubes,
one in the center and six around it. They fit perfectly in the 3" tube. There's
a 3" centering ring that seals the ends six outboard tubes.

The recommended motors were some F (I forget, but it's got to be a 24mm), and
a G42. It's a heavy rocket, and is just begging to be clustered.

So, anybody have some suggestions??

Thanks!
--

 
 
 

Stovi modifications

Post by JImbo Fran » Tue, 24 Mar 1998 04:00:00


Be sure to check CG with all those motors (does it come with nose weight?), the
additional tubes in the back may make it a bit tail heavy already. Cool looking
rocket!

Quote:

> I picked up a LOC Stovi over the weekend and would like to know if anyone
> out there has modified this kit for clusters. The instructions have the
> nice disclaimer "LOC does not recommend using motors in the outboard tubes" (or
> something like that).

> For those of you not familiar with the kit, it's 3" diameter at the bottom,
> with a transition to 2.2" at the payload. There are seven 24mm motor tubes,
> one in the center and six around it. They fit perfectly in the 3" tube. There's
> a 3" centering ring that seals the ends six outboard tubes.

> The recommended motors were some F (I forget, but it's got to be a 24mm), and
> a G42. It's a heavy rocket, and is just begging to be clustered.

> So, anybody have some suggestions??

> Thanks!
> --


--
Jimbo - Renegade Intellectual
Attaching the electrodes of knowledge to the ***s of ignorance.
The trouble with good ideas is that they soon degenerate into a lot of hard work.
The advantage of the emotions is that they lead us astray.

Perspective is everything

 
 
 

Stovi modifications

Post by The Silent Observe » Tue, 24 Mar 1998 04:00:00


Quote:

> I picked up a LOC Stovi over the weekend and would like to know if anyone
> out there has modified this kit for clusters. The instructions have the
> nice disclaimer "LOC does not recommend using motors in the outboard tubes" (or
> something like that).

> For those of you not familiar with the kit, it's 3" diameter at the bottom,
> with a transition to 2.2" at the payload. There are seven 24mm motor tubes,
> one in the center and six around it. They fit perfectly in the 3" tube. There's
> a 3" centering ring that seals the ends six outboard tubes.

> The recommended motors were some F (I forget, but it's got to be a 24mm), and
> a G42. It's a heavy rocket, and is just begging to be clustered.

> So, anybody have some suggestions??

I've seen a Stovi flown on a cluster -- using, IIRC, a 24mm G in the
core and with all the outboard tubes filled with D12-0s (I don't recall
seeing vents in the outboard tubes, but they should have them if you'll
used boosters rather than plugged outboards.

The problems with this setup are, first, that it requires nose weight
for stability; second, that it's completely dependent on the core motor
for ejection, and third that it's not much rocket for H total impulse (G
and 6xD12, about 220+ Ns).

To elaborate, the one I've seen flown in this configuration failed to
ignite the core, and avoided becoming a lawn dart only by "virtue" of
being unstable -- it turned one loop in a full stalled, 90 degree AOA
condition, briefly pointed at the LCO chair (where I was hoping the core
wouldn't come up to pressure as it turned), and then flopped on the
ground without damage.  Total altitude less than 50 feet.  I'm told it
was reflown the next day, with successful core ignition, but I don't
know if nose weight was added or not -- I hope so...

--
Better freedom and a chilly road than a warm hearth and servitude.
                                                              -- Fafhrd

Donald Qualls, aka The Silent Observer           NAR # 70141-SR Insured
Rocket Pages             http://members.aol.com/silntobsvr/launches.htm

Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.

 
 
 

Stovi modifications

Post by Chuck Wald » Wed, 25 Mar 1998 04:00:00


I just built and lost a Stovi.  I modified the outboards for BP
engines and used the center tube for the ejection charge.

The first test flights were attempted at the TARA launch in Fort
Valley last week but the E30 spit the Copperhead on both tries.  I
switched igniters and launched it two days later with better results
off the pad.

I went with an E30-4 because I wanted to test the rocket with a small
motor.  Don't do this.  The first launch cleared the pad, made it
about 300 feet off the ground, and popped the 'chute with just enough
time to recover safely.

The second launch reached about the same altitude but the Aerotech
bonus delay I got popped the 'chute at an altitude of approximately
two inches.  The rocket hit the asphalt with enough force to dig a
two-inch hole and rip the forward tube in half.  The rear section was
blown sideways by the ejection charge and split open when it hit the
ground.  The only parts that are reusable are the launch lug,
transition, and perhaps the fins.  The rocket is not a flimsy design,
it just hit the ground with a whole lot of speed.

My opinion is that the Stovi looks cool but is severely handicapped by
a too-small motor mount.  Remember, the Stovi is pretty tail-heavy
with marginal fin area.  If you cluster it you will have to add nose
weight to compensate.  The rocket is heavy enough that if you cluster
it and have a failure you will be flying a very heavy, underpowered
rocket with an armored nose cone.  

Here's what I suggest.  I think LOC is right, your chances of igniting
one AP and six BP motors at the same time are pretty low.  Launch only
with F or G reloadables and you should be fine.  Better yet, cut away
part of the interior sections of the outside tubes and put in a 29mm
center mount.  You should still have just enough room for six 18mm
motors in the outboards.  This way you can launch with G and H engines
and use C BP or D composites in the outboards.  A G or H will have
enough excess power to fly even if all six outboards fail to light.

I may end up building another one and will probably end up with a 38mm
mount in the tail.  Guess I will have to get L1 certified before I do
that.

Chuck

www.waldencompany.com

 
 
 

Stovi modifications

Post by -Wiersbe,R. » Wed, 25 Mar 1998 04:00:00




Quote:
>Be sure to check CG with all those motors (does it come with nose weight?), the
>additional tubes in the back may make it a bit tail heavy already. Cool looking
>rocket!

Yeah, I'd already thought of that. Lots of room in the nose, so that won't be
a problem. I'm just surprised at how much the darn thing weighs, and I'd be
more comfortable flying it on something besides a single 24mm F or G (that and
the fact that I don't have any :)

I was thinking of maybe a 24mm F39(?) reload in the core with a couple of
D12's might work, or a cluster of 3 24mm reloads. I haven't looked at the
numbers yet, just thought I'd see what wisdom existed on the net.

Thanks!

Quote:

>> I picked up a LOC Stovi over the weekend and would like to know if anyone
>> out there has modified this kit for clusters. The instructions have the
>> nice disclaimer "LOC does not recommend using motors in the outboard tubes" (or
>> something like that).

--

 
 
 

Stovi modifications

Post by -Wiersbe,R. » Wed, 25 Mar 1998 04:00:00



Quote:

>I just built and lost a Stovi.  I modified the outboards for BP
>engines and used the center tube for the ejection charge.

>I went with an E30-4 because I wanted to test the rocket with a small
>motor.  Don't do this.  The first launch cleared the pad, made it
>about 300 feet off the ground, and popped the 'chute with just enough
>time to recover safely.

I would think an E30 wouldn't even get this thing 300 feet up. This
thing is _heavy_!! Maybe mine's got a thicker nose cone or transition.

Quote:
>My opinion is that the Stovi looks cool but is severely handicapped by
>a too-small motor mount.  Remember, the Stovi is pretty tail-heavy
>with marginal fin area.  If you cluster it you will have to add nose
>weight to compensate.  The rocket is heavy enough that if you cluster
>it and have a failure you will be flying a very heavy, underpowered
>rocket with an armored nose cone.  

I agree about the too small motor mount, and the CP/CG relationship.
The last line above is the one that worries me.

Quote:
>Here's what I suggest.  I think LOC is right, your chances of igniting
>one AP and six BP motors at the same time are pretty low.  

I was thinking of venting all of the tubes into the 3" body, so even if
the core didn't ignite it would eject. That assumes that all of the motors
are the same (or about the same), and that the model can still safely
fly if one or more _don't_ ignite. It does get tricky.

Quote:
>Launch only
>with F or G reloadables and you should be fine.  Better yet, cut away
>part of the interior sections of the outside tubes and put in a 29mm
>center mount.  You should still have just enough room for six 18mm
>motors in the outboards.  This way you can launch with G and H engines
>and use C BP or D composites in the outboards.  A G or H will have
>enough excess power to fly even if all six outboards fail to light.

I was thinking of putting in a 29mm core tube, and either using 18mm
tubes around the outside or cutting the 24mm ones (I'd rather save them
for motor mounts and use 18mm tubes though). If I go that route I'll
probably airstart the outboards.

Thanks for the feedback!

--

 
 
 

Stovi modifications

Post by Konrad Hambri » Wed, 25 Mar 1998 04:00:00



Quote:



>>Be sure to check CG with all those motors (does it come with nose weight?), the
>>additional tubes in the back may make it a bit tail heavy already. Cool looking
>>rocket!

>Yeah, I'd already thought of that. Lots of room in the nose, so that won't be
>a problem. I'm just surprised at how much the darn thing weighs, and I'd be
>more comfortable flying it on something besides a single 24mm F or G (that and
>the fact that I don't have any :)

>I was thinking of maybe a 24mm F39(?) reload in the core with a couple of
>D12's might work, or a cluster of 3 24mm reloads. I haven't looked at the
>numbers yet, just thought I'd see what wisdom existed on the net.

Bob --

I did not realize this was a cluster rocket !

An AT G55-10W or seven might be fun ;-)

-- kjh
--
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1111 Seacoast Dr.  Unit 41   |  home:   (619) 423-4451     |
Imperial Beach, CA   91932   |                             |

 
 
 

Stovi modifications

Post by -Wiersbe,R. » Thu, 26 Mar 1998 04:00:00



Quote:





>>>Be sure to check CG with all those motors (does it come with nose weight?), the
>>>additional tubes in the back may make it a bit tail heavy already. Cool looking
>>>rocket!

>>Yeah, I'd already thought of that. Lots of room in the nose, so that won't be
>>a problem. I'm just surprised at how much the darn thing weighs, and I'd be
>>more comfortable flying it on something besides a single 24mm F or G (that and
>>the fact that I don't have any :)

>>I was thinking of maybe a 24mm F39(?) reload in the core with a couple of
>>D12's might work, or a cluster of 3 24mm reloads. I haven't looked at the
>>numbers yet, just thought I'd see what wisdom existed on the net.

>Bob --

>I did not realize this was a cluster rocket !

It isn't, just a core 24mm with 6 empty tubes around it. LOC says not to cluster
it, but I wanted to know if others on the net had tried. It sounds like it's not
that great of a kit to be thinking of clustering it.

Quote:
>An AT G55-10W or seven might be fun ;-)

Yeah! What he said!

--